223205200 1 LTE ENB System Description Ver 5 0 RIL en for Call Flow

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5.0

LTE eNB

System Description

2600-00F22GGA2

Ver. 5.0

COPYRIGHT This manual is proprietary to SAMSUNG Electronics Co., Ltd. and is protected by copyright. No information contained herein may be copied, translated, transcribed or duplicated for any commercial purposes or disclosed to the third party in any form without the prior written consent of SAMSUNG Electronics Co., Ltd.

TRADEMARKS Product names mentioned in this manual may be trademarks and/or registered trademarks of their respective companies.

This manual should be read and used as a guideline for properly installing and operating the product. Al l reas onabl e c are has been made t o ens ur e t hat this docu ment is acc ur ate. If you hav e an y co mmen ts on this manual, please contact our documentation centre at the following address: Addr ess : Docu ment Center 3rd Floor J eong-bo-tong-si n-dong . 129, Samsung -ro, Yeongtong-gu, Suwon-si, Gyeonggi -do, Kor ea 443-742 Homepage: http://www.samsungdocs.com

©2012~2013 SAMSUNG Electro nics Co., Ltd.

All rig hts reserved.

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5.0 INTRODUCTION

INTRODUCTION

Purpose This description describes the characteristics, features and structure of the LTE eNB.

Document Content and Organiza tion This manual consists of five Chapters and a list of Abbreviations. CHAPTER 1. Samsun g L TE System Overvi ew  

Introduction to Samsung LTE System Samsung LTE Network Configuration

CHAPTER 2. LTE eNB Overvi ew 

Introduction to System



Main Functions



Specifications



Intersystem Interface

CHAPTER 3. LTE eNB Structure 

Hardware Structure



Software Structure

CHAPTER 4. Message Flow 

Call Processing Message Flow



Data Traffic Flow



Network Sync Flow



Alarm Signal Flow



Loading Flow



Operation and Maintenance Message Flow

© SAMSUNG Electronics Co., Ltd.

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Ver. 5.0 INTRODUCTION

CHAPTER 5. Supplementary Functi ons and Tool s 

Web-EMT



CLI



RET

AB BREVIA TIONS

Definitions of the abbreviations used in this manual.

Conventions The following types of paragraphs contain special information that must be carefully read and thoroughly understood. Such information may or may not be enclosed in a rectangular box, separating it from the main text, but is always preceded by an icon and/or a bold title.

NOTE Indicates additional information as a reference.

WEEE Symbol Inform ation This marking on the product, accessories or literature indicates that the product and its electronic accessories should not be disposed of with other household waste at the end of their working life. To prevent possible harm to the environment or human health from uncontrolled waste disposal, please separate these items from other types of waste and recycle them responsibly to promote the sustainable reuse of material resources. For more information on safe disposal and recycling, visit our website www.samsung.com/in or contact our Helpline numbers-18002668282, 180030008282.


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5.0 INTRODUCTION

Revision History VERSION

DATE OF ISSUE

5.0

06. 2013.

REMARKS - Deleted the Smart Scheduler server related information (Chapter 5) - ‘Smart Scheduler server system description’ was configured independantly.)

4.0

03. 2013.

- Smart Scheduler server details were added. (1.2, 2.4, Chapter 5) - eMBMS details were added. (1.2, 2.1, 2.2.1, 2.2.3) - Following terms were changed: UADU  CDU, L8HU RRU, LSM-R



LSM, LSM-C





CSM

- Supporting capacity was changed (1 Carrier/3 Sector  1 Carrier/9 Sector, 3 L9CA boards) - Other errors were corrected. 3.0

12. 2012.

- System configuration was changed. (L9CA) - ‘2.1’ was changed. - ‘2.3’ was changed. - ‘3.1.1’ was changed. - ‘3.1.3’ was changed. - ‘Figure 4.14’ was changed.

2.0

08. 2012.

‘2.3’ was changed.

1.0

08. 2012.

First Version


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Ver. 5.0 TABL E OF CONTENTS

TABLE OF CONTENTS

INTRODUCTION

3

Purpose .................................................................................................................................................3 Document Content and Organization .................................................................................................... 3 Conventions........................................................................................................................................... 4 WEEE Symbol Information ....................................................................................................................4 Revision History..................................... ................................................................................................ 5

CHAPTER 1. Samsung LTE System Overview

10

1.1

Intr od uct ion to Samsun g LTE Sys tem ................................................................................... 10

1.2

Samsun g LTE Networ k Conf ig ur atio n ................................................................................... 13

CHAPTER 2. LTE eNB Overv iew

16

2.1

Intr odu cti on to System ...........................................................................................................16

2.2

Main Functions ........................................................................................................................ 18 2.2.1

Physical Layer Processing .................. .................................................................................... 18

2.2.2

Call Processing Function ........................................................................................................ 22

2.2.3

IP Processing..........................................................................................................................24

2.2.4

SON Function................................. ......................................................................................... 25

2.2.5

Easy Operation and Maintenance ..........................................................................................26

2.3

Specifications .......................................................................................................................... 29

2.4

Intersystem Interface .............................................................................................................. 31 2.4.1

Interface Structure................................................................................................................... 31

2.4.2

Protocol Stack.......................................................................................................................... 32

2.4.3

Physical Interface Operation .......................... ......................................................................... 36

CHAPTER 3. System Structure 3.1

37

Hardware Structure ................................................................................................................. 37 3.1.1

CDU......................................................................................................................................... 38

3.1.2

RRU......................................................................................................................................... 41

3.1.3

Power Supply .......................................................................................................................... 42

3.1.4

Cooling Structure..................................................................................................................... 43


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5.0 TABLE OF CONTENTS

3.1.5 3.2

External Interface.................................................................................................................... 44

Software Structure .................................................................................................................. 46 3.2.1

Basic Software Structure ............................. ............................................................................ 46

3.2.2

CPS Block ...............................................................................................................................49

3.2.3

OAM Blocks......................... .................................................................................................... 52

CHAPTER 4. Message Flow

56

4.1

Call Proc essi ng Message Flow ............ .................................................................................. 56

4.2

Data Traffic Flow ..................................................................................................................... 76

4.3

Network Sync Flow ................................................................................................................. 77

4.4

Al arm Sig nal Flo w ................................................................................................................... 78

4.5

Loading Flow ........................................................................................................................... 79

4.6

Operati on and Mainten ance Message Flow .......................................................................... 80

CHAPTER 5. Suppleme ntary Function s and Tools

81

5.1

Web-EMT ................................................................................................................................. 81

5.2

CLI ............................................................................................................................................ 82

5.3

RET .......................................................................................................................................... 83

AB BREVIATION


84

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LIST OF FIGURES Figure 1. Functional Distinctions of E-UTRAN and EPC ............................................................ 11 Figure 2. Samsung LTE System Architecture ............................................................................. 13 Figure 3. Inter-System Interface Structure .................................................................................. 31 Figure 4. Protocol Stack between UE and eNB .......................................................................... 32 Figure 5. Protocol Stack between eNB and S-GW User Plane ................................................... 33 Figure 6. Protocol Stack between eNB and MME Control Plane ................................................ 33 Figure 7. Inter-eNB User Plane Protocol Stack........................................................................... 34 Figure 8. Inter-eNB Control Plane Protocol Stack....................................................................... 34 Figure 9. Interface Protocol Stack between eNB and LSM ......................................................... 35 Figure 10. Protocol Stack between eNB and Smart Scheduler Server ....................................... 35 Figure 11. Protocol Stack between Smart Scheduler Server and LSM ....................................... 36 Figure 12. Internal Configuration of eNB .................................................................................... 37 Figure 13. CDU Configuration .................................................................................................... 38 Figure 14. RRU Configuration .................................................................................................... 41 Figure 15. Power Supply Configuration ...................................................................................... 42 Figure 16. Cooling Structure of CDU .......................................................................................... 43 Figure 17. CDU External Interface.............................................................................................. 44 Figure 18. RRU’s External Interface ........................................................................................... 45 Figure 19. eNB Software Structure ............................................................................................. 46 Figure 20. CPS Structure ............................................................................................................ 49 Figure 21. OAM Structure ........................................................................................................... 52 Figure 22. Attach Process........................................................................................................... 57 Figure 23. Service Request Process by UE ............................................................................... 59 Figure 24. Service Request Process by Network ....................................................................... 61 Figure 25. Detach Process by UE .............................................................................................. 62 Figure 26. Detach Process by MME ........................................................................................... 63 Figure 27. X2-based Handover Procedure ................................................................................. 64 Figure 28. S1-based Handover Procedure ................................................................................. 66 Figure 29. E-UTRAN to UTRAN PS Handover ........................................................................... 69 Figure 30. UTRAN to E-UTRAN PS Handover ........................................................................... 71 Figure 31. CS Fallback to UTRAN Procedure (UE in Active mode, No PS HO support) ............ 73 Figure 32. CS Fallback to GERAN Procedure (UE in Active mode, No PS HO support) ............ 74 Figure 33. Data Traffic Flow ........................................................................................................ 76 Figure 34. Network Synchronization Flow .................................................................................. 77 Figure 35. Alarm flow .................................................................................................................. 78 Figure 36. Loading Signal Flow .................................................................................................. 79 Figure 37. Operation and Maintenance Signal Flow ................................................................... 80


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5.0 TABLE OF CONTENTS

Figure 38. Web-EMT Interface ................................................................................................... 81 Figure 39. RET Interface ............................................................................................................ 83


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Ver. 5.0 CHAPTER 1. Samsung LTE System Overvi ew

CHAPTER 1. Samsu ng L TE Sys tem Overview

1.1

Introd uct ion to Samsung LTE Syst em The Samsung LTE system supports 3GPP LTE (hereinafter, LTE) based services. LTE is a next generation wireless network system which solves the disadvantages of existing 3GPP mobile systems allows high-speed data service at low cost regardless of time and place. The Samsung LTE system supports the Orthogonal Frequency Division Multiple Access (OFDMA) for downlink, the Single Carrier (SC) Frequency Division Multiple Access (FDMA) for downlink, and scalable bandwidths for various spectrum allocation and provides high-speed data service. It also provides high-performance hardware for improved system performance and capacity and supports various functions and services.

Compliance Standards The Samsung LTE system is based on the Rel-8 and Rel-9 standards of the LTE 3rd Generation Partnership Project (3GPP).

The Samsung LTE system consists of the evolved UTRAN Node B (eNB), Evolved Packet Core (EPC) and LTE System Manager (LSM). The eNB exists between the EPC and the User Equipment (UE). It establishes wireless connections with the UE and processes packet calls according to the LTE air interface standard. The eNB manages the UE in connected mode at the Access Stratum (AS) level. The EPC is the system located between the eNB and Packet Data Network to perform various control functions. The EPC consists of the Mobility Management Entity (MME), Serving Gateway (S-GW) and PDN Gateway (P-GW). The MME manages the UE in idle mode at the Non-Access Stratum (NAS) level; and the S-GW and the P-GW manage user data at the NAS level and interworks with other networks. The LSM provides the man-machine interface; manages the software, configuration, performance and failures; and acts as a Self Organizing Network (SON) server.


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5.0 CHAPTER 1. Samsung LTE System Overvi ew

The figure below shows the functional distinctions between the eNB of E-UTRAN, MME, S-GW, and P-GW according to the 3GPP standard. The eNB has a layer structure and the EPC has no layer.

eNB Inter Cell RRM RB Control Connection Mobility Cont. Radio Admission Control MME eNB Measurement Configuration & Provision

NAS Security

Dynamic Resource Allocation(Scheduler)

Idle State Mobility Handling EPS Bearer Control

RRC PDCP

S-GW

RLC

P-GW

S1

MAC

UE IP address allocation

Mobility Anchoring

PHY

Packet Filtering

E-UTRAN

EPC

Figure 1. Function al Distinct ions of E-UTRAN and EPC

eNB

An eNB is a logical network component of the Evolved UTRAN (E-UTRAN) which is on the access side in the LTE system. eNBs can be interconnected with each other by means of the X2 interface. The eNBs are connected by means of the S1 interface to the Evolved Packet Core (EPC). The wireless protocol layer of the eNB is divided into layer 2 and layer 3. Layer 2 is subdivided into the Media Access Control (MAC) layer, the Radio Link Control (RLC) layer, and the PDCP layer, each of which performs independent functions. Layer3 has the Radio Resource Control (RRC) layer. The MAC layer distributes air resources to each bearer according to its priority, and performs the multiplexing function and the HARQ function for the data received from the multiple upper logical channels. The RLC layer performs the following functions. 

Segments and reassembles the data received from the PDCP layer in accordance with the size specified by the MAC layer



Requests retransmission to recover if data transmission fails in the lower layer (ARQ)



Reorders the data recovered by performing HARQ in the MAC layer (re-ordering)


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The PDCP layer performs the following functions. 

Header compression and decompression



Encrypts/decrypts user plane and control plane data



Protects and verifies the integrity of control plane data



Transmits data including sequence number related function



Removes data and redundant data based on a timer

The RRC layer performs mobility management within the wireless access network, maintaining and control of the Radio Bearer (RB), RRC connection management, and system information transmission, etc. MME

The MME interworks with the E-UTRAN (eNB) to process the Stream Control Transmission Protocol (SCTP)-based S1 Application Protocol (S1-AP) signaling messages for controlling call connections between the MME and the eNB and to process the SCTPbased NAS signaling messages for controlling mobility connection and call connection between the UE and the EPC. The MME is responsible for collecting/modifying the user information and authenticating the user by interworking with the HSS. It is also responsible for requesting the allocation/ release/change of the bearer path for data routing and retransmission with the GTP-C protocol by interworking with S-GW. The MME interworks with the 2G and 3G systems, the SGSN and the MSC for providing mobility and Handover (HO), Circuit Service (CS) Fallback and Short Message Service (SMS). The MME is responsible for inter-eNB mobility, idle mode UE reachability, Tracking Area (TA) list management, choosing P-GW/S-GW, authentication, and bearer management. The MME supports mobility during inter-eNB handover and the inter-MME handover. It also supports the SGSN selection function upon handover to a 2G or 3G 3GPP network. S-GW

The S-GW acts as the mobility anchor during inter-eNB handover and inter-3GPP handover, and routes and forwards user data packets. The S-GW allows the operator to apply application-specific charging policies to UE, PDN or QCI and manages the packet transmission layers for uplink/downlink data. The S-GW also supports GPRS Tunneling Protocol (GTP) and Proxy Mobile IP (PMIP) by interworking with the MME, P-GW, and SGSN. PDN Gateway (P-GW)

The P-GW is responsible for charging and bearer policy according to the policy and manages charging and transmission rate according to the service level by interworking with the PCRF. The P-GW also performs packet filtering for each user, IP address allocation for each UE, and downlink data packet transmission layer management.


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1.2

Samsung LTE Network Conf ig uratio n A Samsung LTE system consists of the eNB, LSM, and EPC. The Samsung LTE system comprising multiple eNBs and EPCs (MME, S-GW/P-GW) is a subnet of the PDN, which allows the User Equipment (UE) to access external networks. In addition, the Samsung LTE system provides the LSM and self-optimization function for operation and maintenance of eNBs. The following shows the Samsung LTE system architecture.

PDN Gy

OCS

EPC Gz

Gx

OFCS P-GW Gz

PCRF Sp

S10

S5/S8

TL1

S11

S6a

HSS EMS

MME

S-GW

CSM S1-MME

S1-U

SNMP/FTP/UDP

X2-C

EMS X2-U

LSM SNMP/FTP/UDP

eNB

eNB

RMI

Uu SC-1

MSS Smart Scheduler Server

UE

UE

Figure 2. Samsung LTE System Architectur e

eNB

The eNB is located between the UE and EPC. It processes packet calls by connecting to the UE wirelessly according to the LTE air standard. The eNB is responsible for transmission and receipt of wireless signals, modulation and demodulation of packet traffic signals, packet scheduling for efficient utilization of wireless resources, Hybrid Automatic Repeat Request (HARQ)/ARQ processing, Packet Data Convergence Protocol (PDCP) for packet header compression, and wireless resources control. In addition, the eNB performs handover by interworking with the EPC.


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EPC

The EPC is a system located between the eNB and PDN. The subcomponents of the EPC are the MME, S-GW and P-GW. 

MME: Processes control messages using the NAS signaling protocol with the eNB and performs control plane functions such as UE mobility management, tracking area list management, and bearer and session management.



S-GW: Acts as the anchor for the user plane between the 2G/3G access system and the LTE system, and manages and changes the packet transmission layer for downlink/ uplink data.



P-GW: Allocates an IP address to the UE, acts as the anchor for mobility between the LTE and non-3GPP access systems, and manages/changes charging and the transmission rate according to the service level.

LTE System Manager (LSM)

The LSM provides the user interface for the operator to operate and maintain the eNB. The LSM is responsible for software management, configuration management, performance management and fault management, and acts as a Self-Organizing Network (SON) server. Core System Manager (CSM)

The CSM provides the user interface for the operator to operate and maintain the MME, S-GW, and P-GW. Master SON Server (MSS)

The MSS interoperates with the local SON server as its higher node, making optimized interoperation possible for the multi-LSM. The MSS can work with Operating Support System (OSS) of the service provider who can decide whether to link them. Home Subsc riber Server (HS S)

The HSS is a database management system that stores and manages the parameters and location information for all registered mobile subscribers. The HSS manages key data such as the mobile subscriber’s access capability, basic services and supplementary services, and provides a routing function to the subscribed receivers. Policy and Charging Rule Funct ion (PCR F)

The PCRF server creates policy rules to dynamically apply the QoS and charging policies differentiated by service flow, or creates the policy rules that can be applied commonly to multiple service flows. The P-GW includes the Policy and Charging Enforcement Function (PCEF), which allows application of policy rules received from the PCRF to each service flow.


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Online Chargin g Syst em (OCS)

The OCS collects online charging information by interfacing with S-GW andP-GW. When a subscriber for whom online charging information is required makes a call, the P-GW transmits and receives the subscriber’s charging information by interworking with the OCS. Offli ne Charging System (OFC S)

The OFCS collects offline charging information by interfacing with S-GW and P-GW. The OFCS uses the GTP’ (Gz) or Diameter (Rf) interface to interface with the S-GW and P-GW. Smart Scheduler Server

The Smart Scheduler server is a system to minimize cell interference through the cooperation of eNBs. The Smart Scheduler module in the Smart Scheduler server provides the centralized wireless resource management function for multiple eNBs. The Smart Scheduler server efficiently compensates the cell interference caused by cell split to improve the cell edge throughput per unit area.

Smart Scheduler Server For the further information on the Smart Scheduler Server, please refer the system description of the Smart scheduler server in separate volume.


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Ver. 5.0 CHAPTER 2. LTE eNB Overview

CHAPTER 2. LTE eNB Overv iew

2.1

Introd uct ion to Syst em An LTE eNB, eNB is located between the UE and the EPC. It provides mobile communications services to subscribers according to the LTE air interface standard. The eNB transmits/receives radio signals to/from the UE and processes the modulation and demodulation of packet traffic signals. The eNB is also responsible for packet scheduling and radio bandwidth allocation and performs handover via interface with the EPC. The eNB consists of the Cabinet DU (CDU), a Digital Unit (DU), and the Remote Radio Unit (RRU), a Radio Unit (RU). The CDU is a digital unit (19-inch shelf) and can be mounted into an indoor or outdoor 19inch commercial rack. The RRU is an RF integration module consisting of a transceiver, power amplifier, and filter. It transmits and receives traffic, clock information, and alarm/control messages to and from the CDU. The RRU employs 4Tx/4Rx configuration supporting optic CPRI and can be installed on an outdoor wall or pole. The main features of eNB are as follows: High Compatibility and Inte ropera bility

Because the eNB complies with the specifications released based on the 3GPP standard, it has high compatibility and Interoperability. High-Performance Modular Structure

The eNB has high-performance with the use of high-performance processors. It is easy to upgrade hardware and software because of its modular structure. Support for Advanced RF a nd Antenna Solutions

The eNB adopts the power amplifier to support the wideband operation bandwidth and supports the Multiple Input Multiple Output (MIMO).


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5.0 CHAPTER 2. LTE eNB Overview

6Rx Multi Antenna Support

The eNB can receive up to 6Rx signals in its own sector as well as from the antenna in repeater mode. Separation of CDU and RRU

The eNB consists of the CDU and RRU separately for easy installation and flexible network configuration. For connection between the CDU and RRU, data traffic signals and OAM information are transmitted/received through the Digital I/Q and C&M interface based on the Common Public Radio Interface (CPRI). Physically, optic cables are used. The CDU and RRU are supplied DC -48 V power from a rectifier respectively. 

Flexible Network Configuration The RRU is not a standalone device; it operates interfacing with the CDU. The RRU is highly flexible in its installation, and helps with setting up a network in a variety of configurations depending on the location and operation method.



Easy Installation The optic interface component that interfaces with the CDU and the RF signal processing component is integrated into the RRU, which becomes a very small and very light single unit. The RRU can be installed on a wall, pole, or floor. In addition, as the distance between the RRU and antenna is minimized, the loss of RF signals due to the antenna feeder line can be reduced so that the line can provide more



enhanced RF receiving performance than the existing rack-type eNB. Natural Cooling The RRU is designed to discharge heat effectively through natural cooling without an additional cooling device. No additional maintenance cost is needed for cooling the RRU.



Support for Loopback Test between CDU and RRU The eNB provides the loopback test function to check whether communication is normal on a Digital I/Q and C & M interface between the CDU and RRU.



Remote Firmware Downloading By replacing its firmware, the RRU can be upgraded in terms of service and performance. The operator can download firmware to the RRU remotely using a simple command from the LSM without visiting the station. As a result, the number of visits is minimized, leading to reduced maintenance costs and system operation with ease.



Monitoring Port The operator can monitor the information for the RRU using its debug port.

MBSFN Transmission Support

Since eNB supports MBSFN transmission, same data stream of the time synchronized cells are transmitted to the same subcarriers at the same time so that the UE can recognize the data transmitted from multiple cells as the data transmitted from a single cell and the interference among the cells can be reduced. The sub-frame of the data stream always uses the extended Cyclic Prefix (CP) to prevent interference to the delay spread.


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2.2

Main Functi ons The main functions of the LTE eNB are as follows: 

Physical Layer Processing



Call Processing Function



IP Processing

 

SON Function Interfacing with Auxiliary Devices



Easy Operation and Maintenance

Avai lab il it y of Sy stem Featur es and Fu nc ti on s For availability and provision schedule of the features and functions described in the system manual, please refer to separate documentations.

2.2.1

Physical Layer Processing The eNB transmits/receives data through the radio channel between the EPC and UE. To do so, the eNB provides the following functions. 

OFDMA/SC-FDMA Scheme



Downlink Reference Signal Creation and Transmission



Downlink Synchronization Signal Creation and Transmission



MBSFN Reference Signal Creation and Transmission



Channel Encoding/Decoding



Modulation/Demodulation



Resource Allocation and Scheduling



Link Adaptation



HARQ



Power Control



ICIC



MIMO

OFDMA/SC-FDMA Scheme

The eNB performs the downlink OFDMA/uplink SC-FDMA channel processing that supports the LTE standard physical layer. The downlink OFDMA scheme allows the system to transmit data to multiple users simultaneously using the subcarrier allocated to each user. Depending on the channel status and the transmission rate requested by the user, the downlink OFDM can allocate one or more subcarriers to a specific subscriber to transmit data.


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In addition, when all sub-carriers are divided for multiple users, the eNB can select and assign to each subscriber a sub-carrier with the most appropriate features using the OFDMA scheme, thus to distribute resources efficiently and increase data throughput. For uplink SC-FDMA, which is similar to OFDMA modulation and demodulation, a Discrete Fourier Transform (DFT) is applied to each subscriber in the modulation at the transmitting side. An inverse Discrete Fourier Transform (IDFT) is applied for minimizing the Peak to Average Power Ratio (PAPR) at the transmitting side, which allows continuous allocation of frequency resources available for individual subscribers. As a result, the eNB can reduce the power consumption of the UE. Downlink Reference Signal Creation and Transmission

The UE must estimate the downlink channel to perform the coherent demodulation on the physical channel in the LTE system. The LTE uses the OFDM/OFDMA-based methods for transmitting and therefore the channel can be estimated by inserting the reference symbols from the receiving terminal to the grid of each time and frequency. These reference symbols are called downlink reference signals, and there are 2 types of reference signal defined in the LTE downlink. 

Cell-specific reference signal: The cell specific reference signal is transmitted to every subframe across the entire bandwidth of the downlink cell. It is mainly used for channel estimation, MIMO rank calculation, MIMO precoding matrix selection and signal strength measurement for handover.



UE-specific reference signal: The UE-specific reference signal is used for estimating channel for coherent demodulation of DL-SCH transmission where the beamforming method is used. ‘UE-specific’ means that the reference signal is generally used for channel estimation of a specified UE only. Therefore, the UE-specific reference signal is used in the resource block allocated for DL-SCH only, which is transmitted to the specified UE.

Downlink Synchroniza tion Signal Cre ation and Transmission

The synchronization signal is used for the initial synchronization when the UE starts to communicate with the eNB. There are two types of synchronization signals: Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS). The UE can obtain the cell identity through the synchronization signal. It can obtain other information about the cell through the broadcast channel. Since synchronization signals and broadcast channels are transmitted in the 1.08 MHz range, which is right in the middle of the cell’s channel bandwidth, the UE can obtain the basic cell information such as cell ID regardless of the transmission bandwidth of the eNB.


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MBSFN Reference Signal Creation and Transmi ssi on

In the enhanced/evolved Multimedia Broadcast Multicast Services (eMBMS) system, the MBSFN reference signal of the MBSFN sub-frame in addition to the cell-specific reference signal and UE-specific reference signal used by the existing unicast are used to estimate the downlink physical channel by inserting the reference symbols that can be recognized by the reception layerMBSFN reference signal. The MBSFN reference signal is provided in 7.5 subcarrier spacing in the case of extended CP to the antenna port number 4. Channel Encoding/Decoding

The eNB is responsible for channel encoding/decoding to correct the channel errors that occurred on a wireless channel. In LTE, the turbo coding and the 1/3 tail-biting convolutional coding are used. Turbo coding is mainly used for transmission of large data packets on downlink and uplink, while convolutional coding is used for control information transmission and broadcast channel for downlink and uplink. Modulation/Demodulation

For the data received over the downlink from the upper layer, the eNB processes it through the baseband of the physical layer and then transmits it via a wireless channel. At this time, to transmit a baseband signal as far as it can go via the wireless channel, the system modulates and transmits it on a specific high frequency bandwidth. For the data received over the uplink from the UE through a wireless channel, the eNB demodulates and changes it to the baseband signal to perform decoding. Resource All ocation and Scheduling

To support multiple accesses, the eNB uses OFDMA for downlink and SC-FDMA for uplink. By allocating the 2-dimensional resources of time and frequency to multiple UEs without overlay, both methods enable the eNB to communicate with multiple UEs simultaneously. When the eNB operates in MU-MIMO mode, the same resource also may be used for multiple UEs simultaneously. Such allocation of cell resources to multiple UEs is called scheduling, and each cell has its own scheduler for this function. The LTE scheduler of the eNB allocates resources to maximize the overall throughput of the cell by considering the channel environment of each UE, the data transmission volume required, and other QoS elements. In addition, to reduce interferences with other cells, the eNB can share information with the schedulers of other cells over the X2 interface.


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Link Adaptation

The wireless channel environment can become faster or slower, better or worse depending on various factors. The system is capable of increasing the transmission rate or maximizing the total cell throughput in response to the changes in the channel environment, and this is called link adaptation. In particular, the Modulation and Coding Scheme (MCS) is used for changing the modulation method and channel coding rate according to the channel status. If the channel environment is good, the MCS increases the number of transmission bits per symbol using a high-order modulation, such as 64QAM. If the channel environment is bad, it uses a loworder modulation, such as QPSK and a low coding rate to minimize channel errors. In addition, in the environment where MIMO mode can be used, the eNB operates in MIMO mode to increase the peak data rate of subscribers and can greatly increase the cell throughput. If the channel information obtained is incorrect or modulation method of higher order or higher coding rate than the given channel environment is used, errors may occur. In such cases, the errors can be corrected by the HARD function. H-ARQ

The H-ARQ is a retransmission method in the physical layer, which uses the stop-and-wait protocol. The eNB provides the H-ARQ function to retransmit or combine frames in the physical layer so that the effects of wireless channel environment changes or interference signal level changes can be minimized, which results in throughput improvement. The LTE uses the Incremental Redundancy (IR)-based H-ARQ method and regards the Chase Combining (CC) method as a special case of the IR method. The eNB uses the asynchronous method for downlink and the synchronous method for uplink. Power Control

When transmitting a specific data rate, too high a power level may result in unnecessary interferences and too low a power level may result in an increased error rate, causing retransmission or delay. Unlike in other schemes such as CDMA, the power control is relatively less important in LTE. Nevertheless, adequate power control can improve performance of the LTE system. In the LTE uplink, SC-FDMA is used so that there are no near-far problems that occur in the CDMA. However, the high level of interference from nearby cells can degrade the uplink performance. Therefore, the UE should use adequate power levels for data transmission in order not to interfere with nearby cells. Likewise, the power level for each UE could be controlled for reducing the inter-cell interference level. In the LTE downlink, the eNB can reduce inter-cell interference by transmitting data at adequate power levels according to the location of the UE and the MCS, which results in improvement of the entire cell throughput.


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Inter-Ce ll Interference Coordi nation (ICIC)

Since the UEs within a cell in LTE use orthogonal resources with no interference between the UEs, there is no intra-cell interference. However, if different UEs in neighbor cells use the same resource, interference may occur. This occurs more seriously between the UEs located on the cell edge, resulting in serious degradation at cell edge. A scheme used to relieve such inter-cell interference problem on the cell edgeICIC. is ICIC allows interference signals to be transmitted to other cells in the cell edge area in as small an amount as possible by allocating a basically different resource to each UE that belongs to a different cell and by carrying out power control according to the UE’s location in the cell. The eNBs exchange scheduling information with each another via X2 interface for preventing interferences by resource conflicts at cell edges. If the interference of a neighbor cell is too strong, the system informs the other system to control the strength of the interference system. The ICIC scheme is used to improve the overall cell performance. MIMO

The LTE eNB supports 2Tx/2Rx or 4Tx/4Rx MIMO by default using multiple antennas. To achieve this, there must be in the eNB channel card the RF part that can separately process the baseband part and each path for MIMO processing. The LTE eNB provides high-performance data services by supporting several types of MIMO.

2.2.2

Call Processing Functio n Cell Information Transmission

In a serving cell, the eNB periodically transmits a Master Information Block (MIB) and System Information Blocks (SIBs), which are system information, to allow the UE that receives them to perform proper call processing. Call Control and Air Resource Assignment

The eNB allows the UE to be connected to or disconnected from the network. When the UE is connected to or released from the network, the eNB transmits and receives the signaling messages required for call processing to and from the UE via the Uu interface, and to and from the EPC via the S1 interface. When the UE connects to the network, the eNB performs call control and resource allocation required for service. When the UE is disconnected from the network, the eNB collects and releases the allocated resources.


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Handover

The eNB supports intra-frequency or inter-frequency handover between intra-eNB cells, X2 handover between eNBs, and S1 handover between eNBs. It also processes signaling and bearer for handover. At intra-eNB handover, handover-related messages are transmitted via internal eNB interfaces; at X2 handover, via the X2 interface; at S1 handover, via the S1 interface. To minimize user traffic loss during X2 and S1 handovers, the eNB performs the data forwarding function. The source eNB provides two forwarding methods to the target eNB: direct forwarding via the X2 interface and indirect forwarding via the S1 interface. The eNB allows the UE to receive traffic without loss through the data forwarding method at handover.

Handover Procedure For more information on the handover procedure, see the ‘Message Flow’ section below.

Ad mi ss io n Cont ro l ( AC) The eNB provides capacity-based admission control and QoS-based admission control for a bearer setup request from the EPC so that the system is not overloaded. 



Capacity-based admission control There is a threshold for the maximum number of connected UEs (new calls/handover calls) and a threshold for the maximum number of connected bearers that can be allowed in the eNB. Call admission is determined depending on whether the connected UEs and bearers exceed the thresholds. QoS-based admission control The eNB determines whether to admit a call depending on the estimated PRB usage of the newly requested bearer, the PRB usage status of the bearers in service, and the maximum acceptance limit of the PRB (per bearer type, QCI, and UL/DL).

RLC ARQ

The eNB performs the ARQ function for the RLC Acknowledged Mode (AM) only. When receiving and transmitting packet data, the RLC transmits the SDU by dividing it into units of RLC PDU at the transmitting side and the packet is retransmitted (forwarded) according to the ARQ feedback information received from the receiving side for increased reliability of the data communication.


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QoS Support

The eNB receives the QoS Class Identifier (QCI) in which the QoS characteristics of the bearer are defined and the GBR, the MBR, and the Aggregated Maximum Bit Rate (UEAMBR) from the EPC. It provides the QoS for the wireless section between the UE and the eNB and the backhaul section between the eNB and the S-GW. Via the air interface, it performs retransmission to satisfy the rate control according to the GBR/MBR/UE-AMBR values, priority of bearer defined in the QCI, and scheduling considering packet delay budget, and the Packet Loss Error Rate (PLER). Via the backhaul interface, it performs QCI-based packet classification, QCI to DSCP mapping, and marking for the QoS. It provides queuing depending on mapping results, and each queue transmits packets to the EPC according to a strict priority, etc. In the Element Management System (EMS), in addition to the QCI predefined in the specifications, operator-specific QCI and QCI-to-DSCP mapping can be set. SYNC Handler Func tio n

eNB provides the Synchronization (SYNC) protocol function to the backhaul section between the eNB and MBMS-GW for each Temporary Mobile Group ID (TMGI) of the MBMS bearer from MME.

2.2.3

IP Proc essin g IP QoS

The eNB can provide the backhaul QoS when communicating with the EPC by supporting the Differentiated Services (DiffServ). The eNB supports 8 class DiffServ and mapping between the services classes of the user traffic received from the MS and DiffServ classes. In addition, the eNB supports mapping between the Differentiated Services Code Points (DSCP) and the 802.3 Ethernet MAC service classes. IP Routing

Since the eNB provides multiple Ethernet interfaces, it stores in the routing table the information on which Ethernet interface the IP packets will be routed to. The routing table of the eNB is configured by the operator. The method for configuring the routing table is similar to the standard router configuration method. The eNB supports static routing settings, but does not support dynamic routing protocols such as Open Shortest Path First (OSPF) or Border Gateway Protocol (BGP). IP Multicast Routing

The eNB provides multiple Ethernet interfaces and it stores information on which Ethernet interface IP packets will be routed to in the routing table. The routing table of eNB is configured by the operator in the similar way to the router standard configuration.


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Ethernet/VLAN Interface

The eNB provides Ethernet interfaces and supports the static link grouping, Virtual Local Area Network (VLAN), and Ethernet CoS functions that comply with IEEE 802.3ad for Ethernet interfaces. The MAC bridge function defined in IEEE 802.1D is not supported. The eNB allows multiple VLAN IDs to be set for an Ethernet interface. To support Ethernet CoS, it maps the DSCP value of the IP header to the CoS value of the Ethernet header for Tx packets.

2.2.4

SON Funct ion The SON function supports the self-configuration, self-establishment and self-optimization function. Self-Configuration and Self-Establishment

Self-configuration and self-establishment enable automatic setup of radio parameters and automatic configuration from system ‘power-on’ to ‘in-service’, which minimizes the effort in installing the system. The detailed functions are as follows. 

Self-Configuration  Self-configuration of Initial Physical Cell Identity (PCI)  Self-configuration of initial neighbor information  Self-configuration of initial Physical Random Access Channel (PRACH) information



Self-Establishment  Automatic IP address acquisition  Auto OAM connectivity  Automatic software and configuration data loading  Automatic S1/X2 setup  Self-test

Self-Optimization 



PCI auto-configuration The SON server of the LSM is responsible for allocating the initial PCI in the selfestablishment procedure of a new eNB, detecting a problem automatically, and selecting, changing, and setting a proper PCI when a PCI collision/confusion occurs with the neighbor cells during operation. Automatic Neighbor Relation (ANR) optimization The ANR function minimizes the network operator’s effort to maintain the optimal NRT by managing the NRT dynamically depending on grow/degrow of the neighbor cells. This function automatically configures the initial NRT of each eNB and recognizes environment changes, such as cell grow/degrow or new eNB installation during operation to maintain the optimal NRT. In other words, the ANR function updates the NRT for each eNB by automatically recognizing topology changes such as new neighbor cell or eNB installation/uninstallation and adding or removing the Neighbor Relation (NR) to or from the new neighbor cell.


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

Mobility robustness optimization The mobility robustness optimization function is the function for improving handover performance in the eNB by recognizing the problem that handover is triggered at the incorrect time (e.g. too early or too late) before, after, or during handover depending on UE mobility, or handover is triggered to the incorrect target cell (handover to the wrong cell) and then by optimizing the handover parameters according to the reasons for the problem.



Random Access Channel (RACH) optimization The RACH Optimization (RO) function minimizes the access delay and interference through dynamic management of the parameters related to random access. The RO function is divided into the initial RACH setting operation and the operation for optimizing parameters related to the RACH. The initial RACH setting operation is for setting the preamble signatures and the initial time resource considering the neighbor cells. The operation for optimizing parameters related to the RACH is for estimating the RACH resources, such as time resource and subscriber transmission power required for random access, that change depending on time, and for optimizing the related parameters.



Mobility Load Balancing (MLB) The MLB function monitors the cell’s load. If the load status satisfies the MLB execution condition specified by the operator, this function moves a part of the traffic to a neighbor cell through network-initiated HO. The MLB execution condition is divided into the load equalization condition among multiple carriers, and the overload condition of a cell.

2.2.5

Easy Operatio n and Main tenanc e Through interworking with the management systems (LSM, Web-EMT, and CLI), the eNB provides the maintenance functions such as system initialization and restart, system configuration management, management of fault/status/diagnosis for system resources and services, management of statistics on system resources and various performance data and security management for system access and operation. Graphics and Text Based Console Interfaces

The LSM manages all eNBs in the network using the Database Management System (DBMS). The eNB also interworks with the console terminal to allow the operator to connect directly to the Network Element (NE), rather than through the LSM, and perform the operations and maintenance. The operator can use the graphics-based console interface (Web-EMT, Web-based Element Maintenance Terminal) or the text-based Command Line Interface (CLI) according to user convenience and work purposes. The operator can access the console interfaces without additional software. For the Web-EMT, the operator can log in to the system using Internet Explorer. For the CLI, the operator can log in to the system using the telnet or the Secure Shell (SSH) in the command window.


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The operator can perform the management of configuration and operational information, management of fault and status, and monitoring of statistics and so on. To grow/degrow resources or configure a neighbor list that contains relation of multiple NEs, the operator needs to use the LSM. Operator Authentication Functi

on

The eNB provides the authentication and privilege management functions for the system operators. The operator accesses the eNB using the operator’s account and password via the CLI. At this time, the eNB grants the operator an operation privilege in accordance with the operator’s level. The eNB also logs the access successes and failures for CLI, login history, and so on. Highly -Secured Maintenance

The eNB supports the Simple Network Management Protocol (SNMP) and SSH File Transfer Protocol (SFTP) for security during communications with the LSM, and the Hypertext Transfer Protocol over SSL (HTTPs) and Secure Shell (SSH) during communications with the console terminal. Online Softw are Upgrade

When a software package is upgraded, the EPC can upgrade the existing package while it is still running. The package upgrade is done by downloading a new package  activating of the new package. The download and activation of a new package is performed using the Download menu and Activation menu of the LSM GUI. When upgrading the package, the service stops temporarily at the ‘change to the new package’ step because the existing process needs to be stopped so that the new process can start. Since the operating system does not need to be restarted, the service can be resumed within several minutes. After upgrading the software, the eNB updates the package stored in the internal nonvolatile storage. Call Trace

The eNB supports the call trace function for a specific UE. The operator can enable trace for a specific UE through the MME. The trace execution results such as signaling messages are transmitted to the LSM. IEEE 802.3ah

The eNB provides the IEEE 802.3ah Ethernet OAM function for the backhaul interface. Although the IEEE 802.3ah OAM is for the physical layer, it is located on the MAC layer to support the entire IEEE 802.3 PHY; the 802.3ah OAM frame is created and processed according to the functions defined in the standards.


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The Ethernet OAM functions include the discovery function where the both ends of a link discover each other to monitor the connectivity continuously and deliver the key link events such as dying gasp; the remote loopback function; the link monitoring function to monitor the error packets and deliver an event notification in case of abnormal threshold; and the variable retrieval function for the 802.3ah standard MIB. The eNB supports the response to the 802.3ah OAM function triggered by an external active mode entity, loopback mode operation, and the 802.3ah Ethernet OAM passive mode such as transmission of event notification. OAM Traffic Throttl ing

The eNB provides the operator with the function for suppressing the OAM-related traffic that can occur in the system using the operator command. At this time, the target OAMrelated traffic includes the fault trap messages for alarm reporting and the statistics files generated periodically. For the fault trap messages, the operator can suppress generation of alarms for the whole system or some fault traps using the alarm inhibition command, consequently allowing the operator to control the amount of alarm traffic that is generated. For the statistics files, the operator can control the amount of statistics files by disabling the statistics collection function for each statistics group using the statistics collection configuration command.


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2.3

Specifications Key Spe cific ations

The key specifications of the eNB are as follows: Category

Specifications

Air specification Operating Frequency

TD-LTE 2,300~2,400 MHz

Channel Bandwidth

20 MHz

Capacity

2x2 MIMO with CDD 1 carrier/9 sector

RF Power per Sector

40 W (4Tx Path)

Backhaul Links

100/1000 Base-T (RJ-45, 2 ports) 1000 Base-SX/LX (SFP, 2 ports)

CDU-RRU Interface

CPRI 4.1 (Optic 4.9 Gbps)

Holdover

24 h

Input Power

The following table shows the power specifications for LTE eNB. The LTE eNB complies with UL60950 safety standard for electrical equipment. If the operator wants AC power for the system input voltage, it can be supplied using an additional external rectifier (installed by the provider). Category

Specifications

CDU

-48 VDC (-40~-56 VDC)

RRU

Dimensions and We ight

The following table shows the dimensions and weight of the LTE eNB. Category Dimensions (mm)

Weight (kg)


Specifications CDU

434 (W) × 385 (D) × 88 (H)

RRU

340 (W) × 106 (D) × 425 (H)

CDU

12 or less

RRU

Approx. 14

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GPSR Specifications

The following table shows the specifications of the LTE eNB’s GPS Receiver (GPSR). Category

Specifications

Received Signal from GPS

GPS L1 Signal

Accuracy/Stability

0.02 ppm

Am bience Conditi ons

The following table shows the operating temperature, humidity level and other ambient conditions and related standard of the CDU. Category

Specifications a)

Temperature Condition Humidity Condition

a)

0~50°C 10~90 % 3

The moisture content must not exceed 24 g per 1 m of air. Altitude

-60~1,800 m

Vibration

- Telcordia GR-63-CORE - Earthquake - Office Vibration - Transportation Vibration

Sound Pressure Level

Max. 60 dBA at distance of 0.6 m and height of 1.5 m

EMI

FCC Part 15

a)

Temperature and humidity are measured at 1.5 m above the floor and at 400 mm away from the front panel of the equipment.

The following table shows the ambient conditions and related standard of the RRU. Category

Specifications a)

Temperature Condition Humidity Condition

a)

-10~50°C 5~95 % 3

The moisture content must not exceed 24 g per 1 m of air. Altitude

-60~1,800 m

Earthquake

Earthquake (Zone4)

Vibration

- Telecodia GR-63 Core - Office Vibration - Transportation Vibration

Sound Pressure Level

Max. 65 dBA at 1.5 m distance and 1 m height.

Dust and waterproof rating

IP65

EMI

FCC Part 15

a)

Temperature and humidity are measured at 1.5 m above the floor and at 400 mm away from the front panel of the equipment.


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2.4

Intersy st em Interface

2.4.1

Interf ace Stru ct ur e The eNB provides the following interfaces for interworking between NEs.

PDN

EPC

Gx P-GW

EMS

Sp

CSM TL1

PCRF S10

S5/S8

S6a

S11 S-GW

MME

S1-U EMS eNB

LSM

HSS

S1-MME X2-C eNB X2-U

SNMP/FTP/UDP

Uu

SC-1 SC-1 eNB Smart Scheduler Server

UE

SNMP/FTP/UDP

Figure 3. Inter-System Interface Structure



Interface between eNB and UE The eNB, in compliance with the 3GPP LTE Uu air interface standard, transmits and receives control signals and subscriber traffic to and from the UE.



Interface between eNB and S-GW The interface between S-GW and eNB is 3GPP LTE S1-U, and the physical access method is GE/FE.



Interface between eNB and MME The interface between MME and eNB is 3GPP LTE S1-MME, and the physical access





method is GE/FE. Interface between eNB and neighbor eNB The inter-eNB interface is 3GPP LTE X2-C/X2-U, and the physical access method is GE/FE. Interface between eNB and LSM The interface between the eNB and the LSM complies with the IETF SNMPv2c/SNMPv3 standard, the FTP/SFTP standard, and the proprietary standard of Samsung; the physical connection method is GE/FE.


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



Interface between eNB and Smart Scheduler Server The interface between the eNB and the Smart Scheduler server complies with the UDP standard; the physical connection method is GE. Interface between Smart Scheduler Server and LSM The interface between the Smart Scheduler server and LSM complies with the FTP/SNMP/UDP standard; the physical connection method is GE.

2.4.2

Prot oc ol Stack The inter-NE protocol stack of the eNB is as follows: Protoc ol Stack betw een UE and eNB

The user plane protocol layer consists of the PDCP, RLC, MAC, and PHY layers. The user plane is responsible for transmission of the user data (e.g. IP packets) received from the upper layer. In the User plane, all protocols are terminated in the eNB. The control plane protocol layer is composed of the NAS layer, RRC layer, PDCP layer, RLC layer, MAC layer and PHY layer. The NAS layer is located on the upper wireless protocol. It performs UE authentication between UE and MME, security control, and paging and mobility management of UE in the LTE IDLE mode. In the control plane, all protocols except for the NAS signal are terminated in the eNB.

NAS

NAS Relay

RRC PDCP

RRC

S1-AP

PDCP

SCTP

S1-AP SCTP

RLC

RLC

IP

IP

MAC

MAC

L2

L2

L1 UE

L1 LTE-Uu

L1 eNB

L1 S1-MME

MME

Figure 4. Protocol Stack between UE and eNB


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Protoc ol Stack between eN B and EPC

The eNB and the EPC are connected physically through the FE and GE method, and the connection specification should satisfy the LTE S1-U and S1-MME interface. In the user plane, the GTP-User (GTP-U) is used as the upper layer of the IP layer; and in the Control plane, the SCTP is used as the upper layer of the IP layer. The figure below shows the user plane protocol stack between the eNB and S-GW.

User Plane PDUs

User Plane PDUs

GTP-U

GTP-U

UDP

UDP

IP

IP

L2

L2

L1

L1

eNB

S1-U

S-GW

Figure 5. Protocol Stack between eNB and S-GW User Plane

The figure below shows the control plane protocol stack between the eNB and MME.

S1-AP

S1-AP

SCTP

SCTP

IP

IP

L2

L2

L1

L1

eNB

S1-MME S1-MME

MME

Figure 6. Protocol Stack between eNB and MME Control Plane


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Inter-eNB Protocol Stack

The eNB and the eNB are connected physically through the FE and GE method, and the connection specification should satisfy the LTE X2 interface. The figure below shows the inter-eNB user plane protocol stack.

User Plane

User Plane

PDUs

PDUs

GTP-U

GTP-U

UDP

UDP

IP

IP

L2

L2

L1

L1

eNB

X2

eNB

Figure 7. Inter-eNB User Plane Protocol Stack

The figure below shows the control plane protocol stack.

X2-AP

X2-AP

SCTP

SCTP

IP

IP

L2

L2

L1

L1

eNB

X2

eNB

Figure 8. Inter-eN B Contr ol Plane Protocol Stack


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Protoc ol Stack b etween e NB and LSM

The FE and GE are used for the physical connection between eNB and LSM, and the connection specifications must satisfy the FTP/SNMP interface. The figure below shows the user plane protocol stack between the eNB and LSM.

FTP

SNMP

FTP

SNMP

TCP

UDP

TCP

UDP

IP

IP

L2

L2

L1

L1

eNB

FTP/SNMP

LSM

Figure 9. Interface Protocol Stack between eNB and LSM

Protoc ol Stack betw een eNB and Smart Scheduler Server (SC -1)

The eNB must provide the interface in CDU for the interoperation with the Smart Scheduler server.

Smart

Smart

Scheduler

Scheduler

Protocol

Protocol

UDP

UDP

IP

IP

L2

L2

L1

L1

eNB

SC-1

Smart Scheduler Sever

Figure 10. Protocol Stack between eNB and Smart Scheduler Server


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Protocol Stack between Smart Scheduler Server and LSM (SNMP/FTP/UDP)

The physical connection uses FE andGE and the connection must bemade via FTP/SNMP/UDP interface. The figure below shows the interface protocol stack between Smart Scheduler server and LSM.

FTP

SNMP

FTP

SNMP

TCP

UDP

TCP

UDP

IP

IP

L2

L2

L1

L1

Smart Scheduler Sever

FTP/SNMP/UDP

LSM

Figure 11. Protocol Stack between Smart Scheduler Server and LSM

2.4.3

Phys ical Interf ace Operation The eNB is the EPC interface which provides the interface of two types: copper and optic interface. The interface type can be selected depending on the network configuration. The number of interfaces to operate can be selected depending on the capacity and required bandwidth of the eNB. The types of interface are as follows: Interface Type

Port Type

Max Port coun t

Copper

1000 Base-T (RJ-45)

2

Optic

1000 Base-LX/SX (SFP)

2


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5.0 CHAPTER 3. System Struc ture

CHAPTER 3. System Structure

3.1

Hard ware Struc tu re LTE eNB is the system consists of the Cabinet DU (CDU) which is a common platform DU, and the Remote Radio Unit (RRU) which is an RU. The CDU is connected to the RRU through CPRI and it can provide up to 1carrier/9sector service. The following figure shows the configuration of the LTE eNB.

R

R

R U (0)

R U (1)

R

…

R U (8)

4.9 Gbps CPRI Interface GPS

Index Data Traffic + Alarm/Control (Ethernet) Alarm/Control Clock CPRI Interface (Optic) Backhaul

CDU

L9CA EPC

FE/GE UDE (FE)

UAMA

Analog 10 MHz 1 PPS UDA (9Rx/2Tx) Rectifier control (RS-485/FE) Power (-48 VDC) Rectifier

Figure 12. Internal Configuration of eNB

4Tx/4Rx is supported by default in the CDU, and up to three L9CAs (LTE eNB Channel card board Assembly) can be mounted. Up to 20 MHz 1 carrier/9 sector can be supported.


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Ver. 5.0 CHAPTER 3. System Struc ture

The L9CA has a capacity of 1 carrier/3 sector (4Tx/4Rx) per board by default. The four slots of the CDU are multi-board type slots where the UAMA carries out the main processor function, network interface function, clock generation and distribution function, provider-requested alarm processing, etc. and the L9CA carries out the modem function. The power module, fan, and air filter are also installed. The RRU is an RF integration module consisting of a transceiver, power amplifier, and filter. It sends and receives traffic, clock information, and alarm/control messages to and from the L9CA. It employs the 4Tx/4Rx configuration with optic CPRI support. Each RRU is connected an optic CPRI; up to three RRUs can be connected to a L9CA.

LTE Mult i-Carrier Multi-Carrier function will be supported after additional schedule, fi vendor required. (to be later)

3.1.1

CDU The CDU is the multi-board type in which the UAMA that carries out the main processor function, network interface function, and clock creation and distribution function and the L9CA that carries out the modem function are mounted. It consists of the power module (PDPM), FANM-C4, and air filter. The CDU is mounted on a 19 inch rack, with fan cooling and EMI available in each unit, and supports a RRU and optic CPRI interface. The following figure shows the CDU configuration:

L9CA

Power

FANM-C4

UAMA

Air filter

Figure 13. CDU Configu ration

The following table shows the key features and configurations of each board. Board UADB

Quantity 1

Description Universal platform type A Digital Backplane board assembly - CDU backboard - Routing signals for traffic, control, clocks, power, etc.


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Board UAMA

Quantity 1

Description Universal platform type A Management board Assembly - Main processor in the system - Resource allocation/operation and maintenance - Collects alarms and reports them to the LSM. - Backhaul support (GE/FE) - CDU fan alarm processing - Rectifier alarm interface - User Defined Ethernet (UDE) and User Defined Alarm (UDA) - Generation and supply of GPS clocks

L9CA

Max. 3

LTE eNB Channel card board Assembly - Call processing, resource assignment, operation, and maintenance - OFDMA/SC-FDMA Channel Processing - CPRI optic interface with RRU (E/O and O/E conversion in CPRI Mux) - Max 1 Carrier/3 Sector @20 MHz, Max. 4Tx/4Rx (UL-SIMO) - 3 Optic port

FANM-C4

1

Fan Module-C4 CDU cooling fan module

UAMA

The functions of the UAMA are as follows: 

Main processor The UAMA is the main processor of the eNB. The UAMA performs communication path setup between the UE and the EPC, Ethernet switching within the eNB, system operation and maintenance. It also manages the status for all hardware/software in the eNB, allocates and manages resources, collects alarms, and reports all status information to the LSM.



Network interface The UAMA directly interfaces with the EPC through the GE/FE and supports a total of four ports (two optic and two copper ports). If only one type of port (either optic or copper) is used, ports not in use can be other UDEs.



External interfacing The UAMA provides Ethernet interface for UDE on the CDU. The UAMA also provides the path to the alarm information generated in the external devices (auxiliary devices provided by a service provider), and reports such alarm





information to the LSM. Reset The UAMA provides the reset function for each board. Clock generation and distribution When the eNB operates independently, the UAMA creates the 10 MHz, even System Frame Number (SFN) by using the signal [PP2S (Even Clock), Digital 10 MHz] received from the Universal Core Clock Module (UCCM), and distributes it to the hardware blocks in the system.


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These clocks are used to maintain internal synchronization in the eNB and operate the system. The UAMA also provides the analog 10 MHz and 1 pps for interworking with measuring equipments. The UCCM transmits the time and location information through the Time Of Day (TOD) path. If it is unable to receive the GPS signal due to fault, it performs the holdover function to provide the existing normal clock for a specific time period. L9CA

The functions of the L9CA are as follows: 

Subscriber channel processing The L9CA modulates the packet data received from the UAMA and transmits it through the CPRI to the RRU. Reversely, it demodulates the data received from the RRU and converts it to the format defined in the LTE physical layer standard and transmits it to the UAMA.



CPRI interface The L9CA interfaces with the RRU through CPRI. As the L9CA contains a built-in Electrical to Optic (E/O) conversion device and an Optic to Electrical (O/E) conversion device, it can transmit and receive ‘Digital I/Q and C & M’ signals between remote RRUs. The L9CA can also run loopback tests to check whether the interface between the L9CA and RRUs is in good condition for proper communication. If necessary, the operator can run loopback tests using the LSM command.

FANM-C4

The FANM-C4 is the system’s cooling fan used to maintain the internal CDU shelf temperature. With this fan, the system can operate normally when the outside temperature of the CDU shelf changes.


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3.1.2

RRU The RRU is installed outdoor by default, adopts a natural cooling system. The RRU, having 4Tx/4Rx RF chains, is an integrated RF module consisting of a transceiver, a power amplifier, and a filter in an outdoor enclosure. The major functions of the RRU are as follows:  

2.3 GHz (2,300~2,400 MHz) Supports 20 MHz 4Tx/4Rx per RRU



Supports contiguous 20 MHz 1 carrier/1 sector



10 W per path (Total 40 W)



Up/Down RF conversion



Performs LNA function



Amplifies the RF signal level



Suppresses spurious waves from the bandwidth



Includes E/O and O/E conversion module for the optical communication with CDU



Supports Remote Electrical Tilt (RET)

[Front View]

[Bottom View]

Figure 14. RRU Configur ation

In the downlink path, the RRU performs O/E conversion for the baseband signals received from the CDU via the optic CPRI. The converted O/E signals are converted again into analog signals by the DAC.


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The frequency of those analog signals is converted upward through the modulator and then those signals are amplified into high-power RF signals through the power amplifier. The amplified signals are transmitted to the antenna through the filter part. In the uplink path, the RF signals received through the filter of the RRU are low-noise amplified in the Low Noise Amplifier (LNA) and their frequency is then down-converted through the demodulator. These down-converted frequency signals are converted to baseband signals through the ADC. The signals converted into baseband are changed to E/O through the CPRI and transmitted to the CDU. The control signals of the RRU are transmitted through the control path in the CPRI. To save energy, the RRU provides the function to turn on or off the output of the power amplifier through to the software command set according to traffic changes. When adjusting the maximum output after the initial system installation, the RRU adjusts the voltage applied to the main transistor through the software command set in high/low mode to optimize the efficiency of the system.

3.1.3

Power Suppl y The power diagram below shows the type of power supply to the eNB and connection points.

Rectifier

Rectifier

-48 VDC (-40~-56 VDC) CDU PDPM EMI Filter

-48 VDC (-40~-56 VDC) UADB

U A M A

L 9 C A

L 9 C A

L 9 C A

F A N M C 4

R R U

R R U

R R U

(0)

(1)

(2)

Figure 15. Power Supply Confi guration


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The power for UAMA and L9CAs in the CDU is supplied through the Power Distribution Panel Module (PDPM) and UADB, a backboard. Each board uses the power by converting the -48 VDC provided into the power needed for each part on the board.

3.1.4

Cooling Struct ure CDU

The CDU maintains the inside temperature of the shelf at an appropriate range using a system cooling fans (FANM-C4), With this fan, the system can operate normally when the outside temperature of the CDU shelf changes. The following shows the heat radiation structure of the CDU.

FANM-C4

Air Filter

Figure 16. Cooli ng Structu re of CDU

RRU

The RRU is designed to discharge heat effectively through natural cooling without an additional cooling device.


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3.1.5

Extern al Interf ace External Interfaces of CDU

The following shows the interfaces of CDU. FANM-C4 PWR PWR/ALM -48 V

ACT

RST DBG0 DBG1 L0

L1

L2

L3

L4

L5

EDBG

ACT

RST DBG0 DBG1 L0

L1

L2

L3

L4

L5

EDBG

ACT

RST DBG0 DBG1 L0

L1

L2

L3

L4

L5

EDBG

ACT GPS RST DBG

UDA

BH0 BH1 DE0 U UDE1 EDBG E RC BH2BH31PPS

A/F

A10M GPS

Figur e 17. CDU External Interface

Unit

Interface

Description

PWR

RTN/-48 V

Power Input (RTN/-48 VDC)

FANM-C4

PWR/ALM

FAN Module LED

UAMA

ACT

CPU Active LED

L9CA

Air filter

GPS

UCCM Status LED

RST

Reset Switch (CPU Chip Reset)

DBG

SW Debug (UART, RS-232)

UDA

User Defined Alarm (Rx: 9 port, Tx: 2 port), Mini Champ

BH0, BH1

Copper Backhaul (100/1000 Base-T), RJ-45

UDE0, UDE1

User Defined Ethernet (100 Base-T), RJ-45

EDBG

SW Debug (100 Base-T), RJ-45

REC

Rectifier, RS-485

BH2, BH3

1000 Base-LX/SX, SFP

1PPS

Test Port 1PPS Output (from UCCM), SMA

A10M

Test Port Analog 10 M Output (from UCCM), SMA

GPS

GPS ANT Input (to UCCM), SMA

ACT

L9CA ACT LED

RST

System reset

DBG0, DBG1

UART DSP Debug, USB

L0~L5

RRU IF (CPRI 4.1), Optic

EDBG

Debugger(100 Base-T), RJ-45

A/F

Air filter


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RRU External Interface

The following shows the external interfaces of RRU.

RET

OPT

PWR CAL

ANT_0

ANT_1

ANT_2

ANT_3

Figure 18. RRU’s External Interface

Interface

Description

RET

Remote Electrical Tilt (AISG 2.0)

OPT

DADU interface, ODCP (LC type)

PWR

Power Input (-48 VDC)

CAL

Antenna Calibration Port

ANT_0~3

4Tx/4Rx, N-type female Coupling Port


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3.2

Softw are Struc tu re

3.2.1

Basic Software Struct ure The software of the eNB is divided into three parts: Kernel Space (OS/DD), Forwarding Space (NPC, NP) and User Space (MW, IPRS, CPS, OAM) which are described below.

User Space CPS

IPRS IPRS

OAM

ECMB

GTPB

OSAB

SNMP

ECCB

PDCB

PM

SwM

SCTB

RLCB

FM

TM

CSAB

MACB

CM

Web-EMT

IPSS

DHCP

CLI

TrM

MW DHCP MDS

THS

HAS

DUS

Kernel Space OS

MFS

ENS

Forwarding Space DD

NPC

NP

Hardware

Figure 19. eNB Software Structure

Operatin g System (OS)

The OS initializes and controls the hardware devices and ensures the software is ready to run on the hardware devices. The OS consists of a booter, kernel, root file system (RFS) and utility. 

Booter: Performs initialization on boards. It initializes the CPU, L1/L2 Cache, UART, and MAC and the devices such as CPLD and RAM within each board, and runs the uboot.



Kernel Manages the operation of multiple software processes and provides various primitives to optimize the use of limited resources.



RFS: Stores and manages the binary files, libraries, and configuration files necessary for running and operating the software in accordance with the File-system Hierarchy Standard 2.2 (FHS).


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

Utility: Provides the functions for managing the complex programmable logic device (CPLD), LED, watchdog, and environment and inventory information, measuring and viewing the CPU load, and storing and managing fault information when a processor goes down.

Device Driver (DD)

The DD allows applications to operate normally on devices that are not directly controlled from the OS in the system. The DD consists of the physical DD and virtual DD. 

Physical DD: Provides the interface through which an upper application can configure, control, and monitor the external devices of the processor. (Switch device driver and Ethernet MAC driver, etc.)



Virtual DD: For the physical network interfaces, virtual interfaces are created on the kernel so that the upper applications may control the virtual interfaces instead of controlling the physical network interfaces directly.

Network Processing Control (NPC)

The NPC, via the interfaces with the upper processes such as IPRS and OAM, constructs and manages various tables necessary for processing the packets of the NP software described above, and performs the network statistics collection function and the network status management function. Network Processing (NP)

The NP is the software which processes the packets required for backhaul interface. The functions of the NP are as follows: 

Packet RX and TX



IPv4 and IPv6



Packet queuing and scheduling



MAC filtering



IP Packet forwarding



IP fragmentation and reassembly



Link aggregation



VLAN termination



Access Control List (ACL)

Middleware (MW)

The MW ensures seamless communication between OS and applications on various hardware environments. It provides a Message Delivery Service (MDS) between applications, Debugging Utility Service (DUS), Event Notification Service (ENS), High Availability Service (HAS) for redundancy management and data backup, Task Handling Service (THS), Miscellaneous Function Service (MFS).


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

MDS: Provides all services related to message transmitting and receiving.



DUS: Provides the function for transmitting debugging information and command between the applications and the operator.



ENS: Adds and manages various events such as timers, and provides the function for transmitting an event message to the destination at the time when it is needed.



HAS: Provides the data synchronization function and the redundancy state



management function. THS: Provides the task creation/termination function, the task control function, and the function for providing task information, etc.



MFS: The MFL is responsible for all hardware-dependent functions, such as accessing physical addresses of hardware devices.

IP Routing Software (IPRS )

The IPRS is the software that provides the IP routing and IP security function for the eNB backhaul. The IPRS is configured with IPRS, IP Security Software (IPSS) and Dynamic Host Configuration Protocol (DHCP), and each of them provide the functions as follows. 

IPRS: Collects and manages the system configuration and status information necessary for IP routing. Based on this data, the IPRS provides the function for creating routing information.  Managing Ethernet, VLAN-TE, and link aggregation  Ethernet OAM  IP addresses management  IP routing information management  QoS management



IPSS: Software that performs the security function for the IP layer. It is responsible for filtering based on the IP address, TCP/UDP port number and protocol type.



DHCP: Software block that performs the automatic IP address allocation function. It is responsible for obtaining an IP address automatically by communicating with the DHCP server.

Boards that Run Software In the following sections, the Master OAM Board and Call Processing Board, where the software runs on, indicate the UAMA and L9CA of CDU each.


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3.2.2

CPS Bl oc k The Call Processing Software (CPS) block performs the resource management of the LTE eNB and the call processing function in the eNB defined in the 3GPP and performs the interface function with the EPC, UE, and neighbor eNBs. The CPS consists of the eNB control processing subsystem (ECS) which is responsible for network access and call control functions, and the eNB data processing subsystem (EDS) which is responsible for user traffic handling. In addition, depending on the eNB functions defined in 3GPP, the ECS consists of SCTB, ECMB, ECCB, SCTB, CSAB and TrM; and the EDS consists of GTPB, PDCB, RLCB and MACB. The following shows the CPS structure.

CPS Master OAM Board SCTB

GTPB

ECMB

PDCB

ECCB

TrM

Call Processing Board

RLCB

MACB

CSAB

Figure 20. CPS Structure

Stream Control Transmission

protocol Block (SCTB)

The SCTB is responsible for establishing the S1 interface between the eNB and the MME, and establishes the X2 interface between neighbor eNBs. It operates on the master OAM board. The major functions of the SCTB are as follows: 

S1 interfacing



X2 interfacing

eNB Common Manageme nt Bloc k (ECMB)

The ECMB performs call processing function such as the system information transmission and the eNB overload control for each eNB and cell. It operates on the master OAM board. The major functions of the ECMB are as follows: 

Setting/Releasing cell



Transmitting system information


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

eNB overload control



Access barring control



Resource measurement control



Transmission of cell load information

eNB Call Contr ol Bl ock (ECCB)

The ECCB performs the function to control the call procedure until exit after call setup and the call processing function for the MME and neighbor eNBs. It operates on the master OAM board. The major functions of the ECCB are as follows: 

Radio resource management



Idle to Active status transition



Setting/changing/releasing bearer



Paging Functions



MME selection/load balancing



Call admission control



Security function

 

Handover control UE measurement control



Statistics processing



Call processing function related to the SON (Mobility Robustness, RACH optimization)

CPS SON Agent B lock (CSAB)

The CSAB supports the SON function which is performed in the eNB CPS. It operates on the master OAM bard. The major functions of the CSAB are as follows: 

Mobility robustness optimization



RACH optimization



Mobility load balancing


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GPRS Tunnelin g Protoc ol Bl ock (GTPB)

The GTPB is the user plane call processing function of the eNB. It processes the GTP. It operates on the master OAM board. The major functions of the GTPB are as follows: 

GTP tunnel control



GTP management



GTP data transmission

Trace Management (TrM)

The TrM updates the trace data and Call Summary Log (CSL) which are received from each software entity (PDCP, MAC and RLC). The updated data is periodically transmitted to the LSM. It operates on the master OAM board. The major functions of the TrM are as follows: 

Signaling based trace



Cell traffic trace



CSL function



Trace data transmission to the Trace Collection Entity (TCE) address

PDCP Block (PDCB)

The PDCB is the user plane call processing function of the eNB. It processes the PDCP. It operates on the master OAM board. The major functions of the PDCB are as follows: 

Header compression or decompression (ROHC only)



Transmitting user data and control plane data



PDCP sequence number maintenance



DL/UL data forwarding at handover



Ciphering and deciphering for user data and control data



Control data integrity protection



Timer-based PDCP SDU discarding

Radio Li nk Control Block (RLCB)

The RLCB is the user plane call processing function of the eNB. It processes the RLC protocol. It operates on the call processing board. The major functions of the RLCB are as follows: 

Transmission for the upper layer PDU


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

ARQ function used for the AM mode data transmission



RLC SDU concatenation, segmentation and reassembly



Re-segmentation of RLC data PDUs



In sequence delivery



Duplicate detection



RLC SDU discard



RLC re-establishment Protocol error detection and recovery



Medium Access Control Block (MACB)

The MACB is the user plane call processing function of the eNB. It processes the MAC protocol and operates on the call processing board. The major functions of the MACB are as follows: 

Mapping between the logical channel and the transport channel



Multiplexing & de-multiplexing



HARQ



Transport format selection



Priority handling between UEs



3.2.3

Priority handling between logical channels of one UE

OAM Blo ck s The Operation And Maintenance (OAM) is responsible for operation and maintenance in the eNB. The OAM is configured with OSAB, PM, FM, CM, SNMP, SwM, TM, Web-EMT and CLI.

OAM Master OAM Board OSAB

SNMP

PM

SwM

FM

TM

CM

Web-EMT/ CLI

Call Processing Board FM

SwM

TM

Figure 21. OAM Structure

The major functions of the OAM are as follows:


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OAM SON Agent B loc k (OSAB)

To allow the operator of a management system to perform the LTE SON function of the eNB, the OSAB supports the automatic configuration & installation of system information, and automatic creation & optimization of a neighbor list. The OSAB operates on the master OAM board. The main functions are as follows: 

System information, automatic configuration, and automatic installation



Optimizing automatic neighbor relation

Performance Management (PM)

PM collects and provides performance data so that the operator of the management system can determine the performance of the LTE of eNB. The PM collects events and performance data during system operation and transmits them to the management systems. Overall statistics files are generated in binary form every 15 minutes, and these files are collected in the management system via FTP/SFTP on the regular basis. The main functions are as follows: 

Collecting statistics data



Storing statistics data



Transmitting statistics data

Fault Management (FM)

The FM performs the fault and status management functions on the eNB’s hardware and software. The FM applies filtering to a detected fault, notifies the management system, and reflects the fault severity and threshold changes in the fault management. The FM operates on the master OAM board and call processing board. The main functions are as follows: 

Detecting faults and reporting alarms



Viewing alarms



Alarm filtering



Setting alarm severity



Setting alarm threshold

 

Alarm correlation Status management and reporting



Status retrieval

Config uration Management (CM )

The CM manages the eNB configuration and parameters in PLD format and provides the data that the software blocks need. Through the command received from SNMP/CLI/WebEMT, the CM provides the functions that can grow/degrow the system configuration, and © SAMSUNG Electronics Co., Ltd.

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display/change the configuration data and operation parameters. The CM operates on the master OAM board. The main functions are as follows: 

Grow/degrow of system and cell



Retrieval, change, grow & degrow of configuration information



Retrieval & change of the call parameters



Retrieval, addition, deletion and change of neighbors

Simple Network Management Proto col (SNMP)

The SNMP is an SNMP agent for supporting a standard SNMP (SNMPv2c/SNMPv3). It performs interfacing with the upper management systems and interoperates with the internal subagents. When receiving a request for a standard MIB object from the LSM, the SNMP processes the request independently. When receiving a request for a private MIB object, it transmits the request to the corresponding internal subagent. The SNMP operates on the master OAM board. The main functions are as follows: 



Processing the standard MIB When receiving a request for an MIB-II object, the SNMP processes it independently and transmits a response. Processing a private MIB When receiving a request for a private MIB object, the SNMP does not process it independently; it transmits it to the corresponding internal subagent. Then the SNMPD receives a response from the subagent and transmits it to the manager.

Soft Ware Management (SwM)

The SwM downloads and runs the package for each board in accordance with the file list downloaded during the preloading procedure. The SwM monitors the software that has been run, provides information on the running software, and supports software restart and upgrade according to the command. The SwM operates on the master OAM board and call processing board. The main functions are as follows: 

Downloading and installing software and data files



Reset of hardware unit and system

 

Status monitoring of the software unit in operation Managing and updating the software and firmware information



Software upgrade



Inventory Management Functions


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Test Management (TM)

The TM checks the internal and external connection paths of system or the validity of its resources. The connection paths are classified into system internal IPC path and external path to other NEs. Moreover, the TM conducts on-demand tests upon the operator’s request and periodic tests according to the schedule set by the operator. The TM operates on the master OAM board and call processing board. The main functions are as follows: 

Enable/disable the Orthogonal Channel Noise Simulator (OCNS)



Setting/clearing a Model



Ping test



Measuring the Tx/Rx power



Measuring the antenna Voltage Standing Wave Ratio (VSWR)

Web-based Element Maintenance Terminal (Web-EMT)

The Web-EMT is a block used to interface with the web client of the console terminal that uses a web browser. It operates as a web server. The Web-EMT support highly secured Secure Sockets Layer (SSL) based HTTP communication. The Web-EMT operates on the master OAM board. The main functions are as follows: 

Web server function



Interoperating with other OAM blocks for processing command

Command L ine Interf ace (CLI)

The CLI is a block to interface with a target CLI when it is connected to a console terminal in the SSH method. The CLI software block processes the CLI command and shows the result. The CLI operates on the master OAM board. The main functions are as follows: 

CLI user management



Command input and result output



Fault/Status message output


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Ver. 5.0 CHAPTER 4. Message Flow


4.1

Call Process in g Message Flow This chapter describes message flow diagrams and functions for attach, service request, detach and handover processes. The handover process includes the intra E-UTRAN handover and inter-RAT (UTRAN) handover processes. As the Inter-RAT (UTRAN, GERAN) interoperation procedure, the message flow and function for the CS Fallback procedure also are described.


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5.0 CHAPTER 4. Message Flow

At tach Pr ocess

The figure below shows the message flow of the Attach procedure.

EPC UE

eNB

1)

S-GW

Random Access Procedure

2)

RRCConnectionRequest

3) 4)

MME

RRCConnectionSetup

RRCConnectionSetupComplete 5)

(ATTACH REQUEST)

Initial UE Message (ATTACH REQUEST)

6)

Authentication/NAS Security Setup

9)

7)

Create Session Request

8)

Create Session Response

Initial Context Setup Request

10) UECapabilityEnquiry

(ATTACH ACCEPT)

11) UECapabilityInformation 13) SecurityModeCommand

12) UE Capability Info Indication

14) SecurityModeComplete 15) RRCConnectionReconfiguration (ATTACH ACCEPT)

16) RRCConnectionReconfiguration Complete Uplink data

Uplink data

17) Initial Context Setup Response 18) ULInformationTransfer (ATTACH COMPLETE)

19) Uplink NAS Transport 20) Modify Bearer Request

(ATTACH COMPLETE)

21) Modify Bearer Response Downlink data

Downlink data

Figure 22. Attach Process

Step

Description

1)

The UE performs the random access procedure (TS 36.321, 5.1) with the eNB.

2)-4)

The UE initializes the RRC Connection Establishment procedure (TS 36.331, 5.3.3). The UE includes the NAS ATTACH REQUEST message in the RRC INITIAL CONTEXT SETUP REQUEST message and sends it to the eNB.


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Step 5)

Description The eNB requests the MME from the RRC elements. The eNB includes the ATTCH REQUEST message in the INITIAL UE message, which is an S1-MME control message, and sends it to the MME.

6)

If there is no UE context for the UE in the network, the integrity for the ATTACH REQUEST message is not protected, or the integrity check fails, an authentication and NAS security setup must be performed. The UE performs the Evolved Packet System (EPS) Authentication and Key Agreement (AKA) procedure (TS 33.401, 6.1.1) with the MME. The MME sets up an NAS security association with the UE using the NAS Security Mode Command (SMC) procedure (TS 33.401, 7.2.4.4).

7)-8)

The MME selects the P-GW and S-GW. The MME sends the Create Session Request message to the S-GW. The S-GW adds an item to the EPS bearer table. From this step to step 20), the S-GW keeps the downlink packet received from the P-GW until the Modify Bearer Request message is received. The S-GW returns the Create Session Request message to the MME.

9)

The MME includes the ATTACH REQUEST message in the INITIAL CONTEXT SETUP REQUEST message, which is an S1-MME Control message, and sends it to the eNB. This S1 message also includes the AS security context information for the UE. This information starts the AS SMC procedure at the RRC level.

10)-12)

If the UE Radio Capability IE value is not contained in the INITIAL CONTEXT SETUP REQUEST message, the eNB starts the procedure for obtaining the UE Radio Capability value from the UE and then sends the execution result to the MME.

13)-14)

The eNB sends the Security Mode Command message to the UE, and the UE responds with the SecurityModeComplete message. In the eNB, downlink encryption must start after Security Mode Command is transmitted and the uplink decryption must start after Security Mode Complete is received. In the UE, the uplink encryption must be started after the SecurityModeComplete message has been sent, and the downlink decryption must be started after the SecurityModeCommand message has been received (TS 33.401, 7.2.4.5).

15)-16)

The eNB includes theATTACH ACCEPT message in the RRCConnectionReconfiguration message and sends it to the UE. The UE sends the RRCConnectionReconfiguration Complete message to the eNB. After receiving the ATTACH ACCEPT message, the UE can send uplink packets to both of the S-GW and P-GW via the eNB.

17)

The eNB sends the INITIAL CONTEXT SETUP RESPONSE message to the MME.

18)-19)

The UE includes the ATTACH COMPLETE message in the ULInformationTransfer message and sends it to the eNB. The eNB includes the ATTACH COMPLETE message in the UPLINK NAS TRANSPORT message and relays it to the MME.

20)-21)

After receiving both of the INITIAL CONTEXT RESPONSE message at step 17) and the ATTACH COMPLETE message at step 19), the MME sends the Modify Bearer Request message to the S-GW. The S-GW sends the Modify Bearer Response message to the MME. S-GW can send the stored downlink packet.


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Service Reque st Ini tiated by t he UE

The figure below shows the message flow of the Service Request procedure initiated by the UE.

EPC UE

eNB

1)

S-GW

Random Access Procedure

2) 3) 4)

MME

RRCConnectionRequest RRCConnectionSetup

RRCConnectionSetupComplete

5)

(SERVICE REQUEST)

6)

Initial UE Message (SERVICE REQUEST)

Authentication/NAS Security Setup

7)

INITIAL CONTEXT SETUP REQUEST (SERVICE ACCEPT)

8)

SecurityModeCommand

9) SecurityModeComplete 10) RRCConnectionReconfiguration (SERVICE ACCEPT)

11) RRCConnectionReconfiguration Complete

Uplink data

Uplink data

12) INITIAL CONTEXT SETUP RESPONSE 13) Modify Bearer Request 14) Modify Bearer Response Downlink data

Downlink data

Figure 23. Service Request Process by UE


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Step

Description

1)

The UE performs the random access procedure with the eNB.

2)-4)

The UE includes the SERVICE REQUEST message, which is an NAS message, in the RRC message that will be sent to the eNB, and sends it to the MME.

5)

The eNB includes the SERVICE REQUEST message in the INITIAL UE message, which is an S1-AP message, and sends it to the MME.

6)

If there is no UE context for the UE in the network, the integrity for the ATTACH REQUEST message is not protected, or the integrity check fails, an authentication and NAS security setup must be performed. The UE carries out the EPS AKA procedure (TS 33.401, 6.1.1) with the MME. The MME sets up an NAS security association with the UE using the NAS SMC procedure (TS 33.401, 7.2.4.4).

7)

The MME sends the S1-AP Initial Context Setup Request message to the eNB. In this step, radio and S1 bearer are activated for all activated EPS bearers.

8)-11)

The eNB sets up the RRC radio bearers. The user plane security is established at this step. The uplink data from the UE can now be passed by the eNB to the S-GW. The eNB sends the uplink data to the S-GW, which, in turn, passes it to the P-GW.

12)

The eNB sends the S1-AP Initial Context Setup Request message to the MME.

13)-14)

The MME sends the Modify Bearer Request message for each PDN connection to the S-GW. Now, the S-GW can send the downlink data to the UE. The S-GW sends the Modify Bearer Response message to the MME.


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Service Request by Network

The message flow for service request procedure by network is illustrated below.

EPC UE

eNB

4)

MME

3)

Paging

5)

S-GW

1)

Downlink Data Notification

2)

Downlink Data Notification

Paging

Acknowledge

UE triggered Service Request procedure

Figure 24. Service Request Process by Network

Step 1)-2)

Description When receiving a downlink data packet that should be sent to a UE while the user plane is not connected to that UE, the S-GW sends the Downlink Data Notification message to the MME which has the control plane connection to that UE. The MME replies to the S-GW with the Downlink Data Notification Acknowledge message. If the S-GW receives additional downlink data packet for the UE, this data packet is stored, and no new Downlink Data Notification is sent.

3)-4)

If the UE is registered with the MME, the MME sends the PAGING message to all eNBs which belong to the TA where the UE is registered. If the eNB receives the PAGING message from the MME, it sends the paging message to the UE.

5)

When the UE in Idle mode receives the PAGING message via the E-UTRAN connection, the Service Request procedure initiated by the UE is started. The S-GW sends the downlink data to the UE via the RAT which has performed the Service Request procedure.


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Detach Init iated by th e UE

The figure below shows the message flow of the Detach procedure initiated by the UE.

EPC UE

eNB 1)

MME

ULInformationTransfer 2)

Uplink NAS Transport (DETACH REQUEST)

5) 6)

S-GW

DLInformationTransfer

3)

Delete Session Request

4)

Delete Session Response

Downlink NAS Transport (DETACH ACCEPT)

(DETACH ACCEPT)

8)

RRCConnectionRelease

7)

UE Context Release Command (Detach)

9)

UE Context Release Complete

Figure 25. Detach Process by UE

Step 1)-2)

Description The UE sends the DETACH REQUEST message, which is an NAS message, to the MME. This NAS message is used to start setting up an S1 connection when the UE is in Idle mode.

3)

The active EPS bearers and their context information for the UE and MME which are in the S-GW are deactivated when the MME sends the Delete Session Request message for each PDN connection.

4)

When receiving the Delete Session Request message from the MME, the S-GW releases the related EPS bearer context information and replies with the Delete Session Response message.

5)-6)

If the detachment procedure has been triggered by reasons other than disconnection of power, the MME sends the DETACH ACCEPT message to the UE.

7)

The MME sets the Cause IE value of the UE CONTEXT RELEASE COMMAND message to ‘Detach’ and sends this message to the eNB to release the S1-MME signal connection for the UE.

8)

If the RRC connection has not yet been released, the eNB sends the RRCConnectionRelease message to the UE in Requested Reply mode. Once a reply to this message is received from the UE, the eNB removes the UE context.

9)

The eNB returns the UE CONTEXT RELEASE COMPLETE message to the MME and confirms that S1 is released. By doing this, the signal connection between the MME and eNB for the UE is released. This step must be performed immediately following step 7).


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Detach Ini tiated by the MME

The figure below shows the message flow of the Detach procedure initiated by the MME.

EPC UE

2)

eNB

MME

1)

DOWNLINK NAS TRANSPORT

DLInformationTransfer

(DETACH REQUEST)

(DETACH REQUEST)

5)

S-GW

3)

Delete Session Request

4)

Delete Session Response

ULInformationTransfer (DETACH ACCEPT)

6)

UPLINK NAS TRANSPORT

7)

UE Context Release Command

9)

UE Context Release Complete

(DETACH ACCEPT)

8)

RRCConnectionRelease

(Detach)

Figur e 26. Detach Process b y MME

Step 1)-2)

Description The MME detaches the UE implicitly if there is no communication between them for a long time. In case of the implicit detach, the MME does not send the DETACH REQUEST message to the UE. If the UE is in the connected status, the MME sends the DETACH REQUEST message to the UE to detach it explicitly.

3)-4)

These steps are the same as Step 3) and 4) in ‘Detach Procedure by UE’.

5)-6)

If the UE has received the DETACH REQUEST message from the MME in step 2), it sends the DETACH ACCEPT message to the MME. The eNB forwards this NAS message to the MME.

7)

After receiving both of the DETACH ACCEPT message and the Delete Session Response message, the MME sets the Cause IE value of the UE CONTEXT RELEASE COMMAND message to ‘Detach’ and sends this message to the eNB to release the S1 connection for the UE.

8)-9)

These steps are the same as Step 8) and 9) in ‘Detach Procedure by UE’.


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LTE Handover-X2-based Handover

The figure below shows the message flow of the X2-based Handover procedure.

EPC UE

Target eNB

Source eNB

Downlink/Uplink data

1)

4)

MME

S-GW


MeasurementReport

RRCConnectionReconfiguration

2)

HANDOVER REQUEST

3)

HANDOVER REQUEST ACKNOWLEDGE

5)

SN STATUS TRANSFER

(mobilityControlinfo)

Data forwarding

6)

Synchronization/UL allocation and timing advance

7) RRCConnectionReconfigurationComplete Forwarded data Uplink data

Uplink data

8)

PATH SWITCH REQUEST 9)

Modify Bearer Request

End marker Forwarded data End marker Downlink data

12) UE CONTEXT RELEASE

Down/Uplink data

Downlink data

11) PATH SWITCH REQUEST ACKNOWLEDGE

10) Modify Bearer Response

Down/Uplink data

Figure 27. X2-based Handover Procedure


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Step 1)

Description The UE sends the Measurement Report message according to the system information, standards and rules. The source eNB determines whether to perform the UE handover based on the MeasurementReport message and the radio resource management information.

2)

The source eNB sends the HANDOVER REQUEST message and the information required for handover to the target eNB. The target eNB can perform management control in accordance with the E-RAB QoS information received.

3)-4)

The target eNB prepares the handover and creates an RRCConnectionReconfiguration message, containing the mobileControlInfo IE that tells the source eNB to perform the handover. The target eNB includes the RRCConnectionReconfiguration message in the HANDOVER REQUEST ACKNOWLEDGE message, and sends it to the source eNB. The source eNB sends the RRCConnectionReconfiguration message and the necessary parameters to the UE to command it to perform the handover.

5)

To send the uplink PDCP SN receiver status and the downlink PDCP SN transmitter status of the E-RABs of which the PDCP status must be preserved, the source eNB sends the SN STATUS TRANSFER message to the target eNB.

6)

After receiving the RRCConnectionReconfiguration message containing mobileControlInfo IE, the UE performs synchronization with the target eNB and connects to the target cell via a Random Access Channel (RACH). The target eNB replies with an allocated UL and a timing advance value.

7)

After having connected to the target cell successfully, the UE notifies the target eNB that the Handover procedure has been completed using an RRCConnectionReconfigurationComplete message.

8)

The target eNB, using the PATH SWITCH REQUEST message, notifies the MME that the UE has changed the cell.

9)-10)

The MME sends the Modify Bearer Request message to the S-GW. The S-GW changes the downlink data path into the target eNB. The S-GW sends at least one ‘end marker’ to the source eNB through the previous path, and releases the user plane resources for the source eNB. The S-GW sends a Modify Bearer Response message to the MME.

11)

The MME acknowledges the PATH SWITCH REQUEST message by issuing the PATH SWITCH REQUEST ACKNOWLEDGE message.

12)

The target eNB sends the UE CONTEXT RELEASE message to the source eNB to notify the handover has succeeded and to make the source eNB release its resources. When receiving the UE CONTEXT RELEASE messages, the source eNB released the radio resource and the control plane resource related to the UE context.


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LTE Handover-S1-based Handover

The figure below shows the message flow of the S1-based Handover procedure.

EPC UE

Target eNB

Source eNB


1)

MME

S-GW


Decision to trigger a relocation via S1

2)

HANDOVER REQUIRED 3)

HANDOVER REQUEST

4)

8)

RRCConnectionReconfiguration (mobilityControlinfo)

7)

HANDOVER REQUEST ACKNOWLEDGE 5) Create Indirect Data Forwarding Tunnel Request 6) Create Indirect Data HANDOVER COMMAND Forwarding Tunnel Response

9)

eNB STATUS TRANSFER 10) MME STATUS TRANSFER

1) 2)

Direct data forwarding Indirect data forwarding Indirect data forwarding

11) Detach from old cell/Synchronize to new cell 12) RRCConnectionReconfigurationComplete Forwarded data Uplink data

Uplink data

13) HANDOVER NOTIFY 14) Modify Bearer Request 15) Modify Bearer Response End marker Forwarded data Downlink data

End marker Downlink data

16) Tracking Area Update procedure 17) UE CONTEXT RELEASE COMMAND 18) UE CONTEXT RELEASE COMPLETE


19) Delete Indirect Data Forwarding Tunnel Request 20) Delete Indirect Data Forwarding Tunnel Response


Figure 28. S1-based Handover Procedure


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Step 1)

Description The source eNB determines whether to perform S1-based handover to the target eNB. The source eNB can make this decision if there is no X2 connection to the target eNB or if an error is notified by the target eNB after an X2-based handover has failed, or if the source eNB dynamically receives the related information.

2)

The source eNB sends the HANDOVER REQUIRED message to the MME. The source eNB notifies the target eNB which bearer is used for data forwarding and whether direct forwarding from the source eNB to the target eNB is possible.

3)-4)

The MME sends the HANDOVER REQUEST message to the target eNB. This message makes the target eNB create a UE context containing the bearer-related information and the security context. The target eNB sends the HANDOVER REQUEST ACKNOWLEDGE message to the MME.

5)-6)

If indirect forwarding is used, the MME sends the Create Indirect Data Forwarding Tunnel Request message to the S-GW. The S-GW replies the MME with the Create Indirect Data Forwarding Tunnel Response message.

7)-8)

The MME sends the HANDOVER COMMAND message to the source eNB. The source eNB creates the RRCConnectionReconfiguration message using the Target to Source Transparent Container IE value contained in the HANDOVER COMMAND message and then sends it to the UE.

9)-10)

To relay the PDCP and HFN status of the E-RABs of which the PDCP status must be preserved, the source eNB sends the eNB/MME STATUS TRANSFER message to the target eNB via the MME. The source eNB must start forwarding the downlink data to the target eNB through the bearer which was determined to be used for data forwarding. This can be either direct or indirect forwarding.

11)

The UE performs synchronization with the target eNB and connects to the target cell via a RACH. The target eNB replies with UL allocation and a timing advance value.

12)

After having synchronized with the target cell, the UE notifies the target eNB that the Handover procedure has been completed using the RRCConnectionReconfigurationComplete message. The downlink packets forwarded by the source eNB can be sent to the UE. The uplink packets can also be sent from the UE to the S-GW via the target eNB.

13)

The target eNB sends the HANDOVER NOTIFY message to the MME. The MME starts the timer which tells when the resources of the source eNB and the temporary resources used by the S-GW for indirect forwarding will be released.

14)

For each PDN connection, the MME sends the Modify Bearer Request message to the S-GW. Downlink packets are sent immediately from the S-GW to the target eNB.

15)

The S-GW sends the Modify Bearer Response message to the MME. If the target eNB changes the path for assisting packet resorting, the S-GW immediately sends at least one ‘end marker’ packet to the previous path.

16)

If any of the conditions listed in section 5.3.3.0 of TS 23.401 (6) is met, the UE starts the Tracking Area Update procedure.


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Step 17)-18)

Description When the timer started at step 13) expires, the MME sends the UE CONTEXT RELEASE COMMAND message to the source eNB. The source eNB releases the resources related to the UE and replies to the target eNB with the UE CONTEXT RELEASE COMPLETE message.

19)-20)

If indirect forwarding hasbeen used, when the timer started at step 13) expires the MME sends the Delete Indirect Data Forwarding Tunnel Request message to the S-GW. This message gets the S-GW to release the temporary resources allocated for indirect forwarding at step 5). The S-GW replies the MME with the Delete Indirect Data Forwarding Tunnel Response message.


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Inter-RAT Handover-LTE to UTRAN PS Handover

Below is the message flow for the PS handover procedure from the E-UTRAN to the UTRAN.

UE

Source eNB

Target RNS

Downlink/Uplink data 1)

Source MME Source S-GW Target SGSN


Target S-GW

P-GW


Handover Initiation 2)

HANDOVER REQUIRED 3)

FORWARD RELOCATION REQUEST 4) Create Session

5) 6)

RELOCATION REQUEST

Request/Response

RELOCATION REQUEST ACKNOWLEDGE 7) 8)

FORWARD RELOCATION RESPONSE 9)

10) HANDOVER COMMAND 11) Mobility from E-UTRAN Command

Create Indirect Data

Create Indirect Data

Forwarding Tunnel Request/Response

Forwarding Tunnel Request/Response

Indirect data forwarding Indirect data forwarding

12) HO to UTRAN Complete 13) RELOCATION COMPLETE 14) FORWARD RELOCATION COMPLETE NOTIFICATION 15) FORWARD RELOCATION COMPLETE ACKNOWLEDGE

16) MODIFY BEARER REQUEST 17) Modify Bearer Request/Response 18) MODIFY BEARER



Response


19) Routing Area Update procedure 20) S1 Release

21) Delete Session Request/Response 22) Create Indirect Data Forwarding Tunnel Request/Response

23) Create Indirect Data Forwarding Tunnel Request/Response

Figur e 29. E-UTRAN to UTRAN PS Hando ver

Step

Description

1)

The source eNB determines the PS handover to the UTRAN. This handover can be determined in accordance with the measurement report received from UE.

2)

The source eNB sends the HANDOVER REQUIRED message to the MME. The source eNB then puts the Source RNC to Target RNC Transparent Container IE information into the message to transmit the information to the target RNC.

3)-4)

The source MME recognizes the handover from the target ID IE of the HANDOVER REQUIRED message to the UTRAN and sends the FORWARD RELOCATION REQUEST message to the target SGSN. The target SGSN determines whether to change the S-GW. Then if change is required, it carries out the Create Session


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Step

Description Request/Response procedure with a new S-GW.

5)-6)

The target SGSN transmits the RELOCATION REQUEST message to the target RNC to request resource allocation for the target RNC. The target RNC carries out the CAC and resource allocation for each RAB for which handover is requested, and transmits the RELOCATION REQUEST ACKNOWLEDGE message containing the result to the target SGSN to respond to the request. The Target RNC to Source RNC Transparent Container IE to transmit to the source eNB is then contained.

7)-9)

To perform the forwarding tunnel setup, the target SGSN carries out the Create Indirect Data Forwarding Tunnel Request/Response procedure with target S-GW and transmits the FORWARD RELOCATION RESPONSE message to the source MME. To perform the forwarding tunnel setup, the source MME carries out the Create Indirect Data Forwarding Tunnel Request/Response procedure with the source S-GW.

10)-11)

The source MME sends the HANDOVER COMMAND message to the source eNB. By doing so, the handover preparation procedure to the target UTRAN is completed. The Source eNB configures the MOBILITY FROM E-UTRAN COMMAND containing the Target RNC to Source RNC Transparent Container IE in the HANDOVER COMMAND message and transmits it to the UE to request the PS handover to the UTRAN.

12)

The UE performs synchronization with the target UTRAN and connects to the target cell via a RACH. After UE is successfully connected to the target cell, UE transmits the HANDOVER TO UTRAN COMPLETE message to the target UTRAN to complete the handover procedure.

13)-15)

The target RNC transmits the RELOCATION COMPLETE message to the target SGSN to notify that the handover procedure from the UE to the UTRAN has been completed successfully. The target SGSN transmits the FORWARD RELOCATION COMPLETE NOTIFICATION message to the source MME. At this time, the source MME operates the waiting timer for releasing the resource of the E-UTRAN and transmits the FORWARD RELOCATION COMPLETE ACKNOWLEDGE response message to the target SGSN. The target SGSN operates the waiting timer for releasing the forwarding tunnel at the time when the source MME receives the response message.

16)-18)

For each PDN connection, thetarget SGSN sends the Modify Bearer Request message to the target S-GW. The downlink packet is then transmitted from the S-GW to the target RNC. The target S-GW carries out the Modify Bearer Request/Response procedure with the P-GW and transmits the Modify Bearer Response message to the target SGSN.

19)

When UE satisfies the conditions specified in section 5.5.2.1 of TS 23.401, the Routing

20)-23)

Area Update procedure starts. When the timer of procedure 14 has expired, the source MME requests the resource release procedure to be carried out on the source eNB and the source S-GW. When the timer of procedure 15 has expired, the target SGSN carries out the resource release allocated for the forwarding tunnel with the target S-GW.


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Inter-RAT Handover-UTRAN to LTE PS Handover

The following shows the message flow for the PS handover procedure from the UTRAN to the E-UTRAN.

UE

Source RNC

Target eNB


Source SGSN Source S-GW

Target MME


Target S-GW

P-GW


Handover Initiation 2)

RELOCATION REQUIRED 3)

FORWARD RELOCATION REQUEST 4)

5) 6)

HANDOVER REQUEST ACKNOWLEDGE 8)

11) HO from UTRAN Command

Create Session

Request/Response

HANDOVER REQUEST

7) Create Indirect Data FORWARD RELOCATION RESPONSE Forwarding Tunnel Request/Response 9) Create Indirect Data

10) RELOCATION COMMAND Forwarding Tunnel Request/Response Indirect data forwarding Indirect data forwarding

12) RRC Connection Reconfiguration Complete 13) HANDOVER NOTIFY 14) FORWARD RELOCATION COMPLETE NOTIFICATION 15) FORWARD RELOCATION COMPLETE ACKNOWLEDGE

16) MODIFY BEARER 17) Modify Bearer

REQUEST

18) MODIFY BEARER Request/Response Downlink/Uplink data

Response



19) Tracking Area Update procedure 20) Iu Release 21) Delete Session Request/Response 22) Delete Indirect Data Forwarding Tunnel Request/Response

23) Delete Indirect Data Forwarding Tunnel Request/Response

Figur e 30. UTRAN to E-UTRAN PS Handover

Step 1)

Description The source RNC determines the PS handover to the E-UTRAN. This decision is made according to the measurement report received from the UE.

2)

The source RNC sends the RELOCATION REQUIRED message to the SGSN. The source RNC then includes the source eNB to target eNB transparent container IE information in the message for relaying the necessary information to the target eNB.

3)-4)

The source SGSN recognizes the handover from the target ID IE of the RELOCATION REQUIRED message to the E-UTRAN and sends the FORWARD RELOCATION


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Step

Description REQUEST message to the target MME. The target MME determines whether to change the S-GW. If change is required, it carries out the Create Session Request/Response procedure with a new S-GW.

5)-6)

The target MME sends the HANDOVER REQUEST message to the target eNB to request resource allocation for the target eNB. The target eNB carries out the CAC and resource allocation for each RAB for which handover is requested, and includes the result in the HANDOVER REQUEST ACKNOWLEDGE message for replying the target MME. At this time, the Target eNB to Source eNB Transparent Container IE to be sent to the source RNC is included.

7)-9)

To perform the forwarding tunnel setup, the target MME carries out the Create Indirect Data Forwarding Tunnel Request/Response procedure with target S-GW and transmits the FORWARD RELOCATION RESPONSE message to the source SGSN. To perform the forwarding tunnel setup, the source SGSN carries out the Create Indirect Data Forwarding Tunnel Request/Response procedure with the source S-GW.

10)-11)

The source SGSN sends the RELOCATION COMMAND message to the source RNC. By doing so, the handover preparation procedure to the target E-UTRAN is completed. The source RNC configures the Handover FROM UTRAN COMMAND message containing the Target eNB to Source eNB Transparent Container IE in the RELOCATION COMMAND message and transmits it to UE to request the PS handover to the E-UTRAN.

12)

The UE performs synchronization with the target E-UTRAN and connects to the target cell via the RACH. After UE is successfully connected to the target cell, the UE sends the RRC CONNECTION RECONFIGURATION COMPLETE message to the target E-UTRAN to complete the handover procedure.

13)-15)

The target eNB then sends the HANDOVER NOTIFY message to the target MME to notify that the handover procedure to the E-UTRAN has been completed successfully. The target MME transmits the FORWARD RELOCATION COMPLETE NOTIFICATION message to the source SGSN. At this time, the source SGSN starts the waiting timer for releasing the resources of the UTRAN and sends the FORWARD RELOCATION COMPLETE ACKNOWLEDGE response message to the target MME. The target MME operates the waiting timer for releasing the forwarding tunnel at the time when the source SGSN receives the response message.

16)-18)

The target MME sends the Modify Bearer Request message for each PDN connection to the target S-GW. Subsequent downlink packets are then sent from the S-GW to the target eNB. The target S-GW performs the Modify Bearer Request/Response procedure with the P-GW and sends the Modify Bearer Response message to the target MME.

19)

When UE satisfies the conditions specified in section 5.5.2.2 of TS 23.401, the Tracking

20)-23)

Area Update procedure starts. When the timer of procedure 14 has expired, the source SGSN requests the resource release procedure to be carried out on the source RNC and the source S-GW. When the timer of procedure 15 has expired, the target MME carries out the resource release allocated for the forwarding tunnel with the target S-GW.


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CS Fallback to UTRAN

The following shows the message flow for the CS Fallback procedure from the E-UTRAN to the UTRAN. The procedure below shows that the CS Fallback procedure is carried out through redirection processing to the UTRAN without PS HO when UE, which is in RRC Connected state, sends the CS call.

UE

Source eNB

Target RNS


MME

S/P-GW

MSC

SGSN


UL INFORMATION TRANSFER/UL NAS TRANSPORT (Extended Service Request) 2)

S1AP Request Message

With CS Fallback indicator 3) S1AP Response ) 5)

easuremen Solicitation (Optional) RRC CONNECTION RELEASE

6)

UE CONTEXT RELEASE REQUEST 7)

8)

S1 Release

UE changes RATthen LAU or Combined RA/LA update orRAU or LAU and RAU 9)

Update bearer(s)

10) RRC/Iu-CS messages (CM Service Request) CS Call Setup

Figure 31. CS Fallback to UTRAN Procedure (UE in Active mode, No PS HO support)

Step 1)

Description In the E-UTRAN, when the UE in RRC Connected state requests CS call setup, the UE creates the EXTENDED SERVICE REQUEST message (NAS) including the CS Fallback Indicator and sends it to the network. The RRC UL INFORMATION TRANSFER message is used for this. The eNB uses the UL NAS TRANSPORT message for relaying it to the MME.

2)-3)

In order to request the eNB for CS Fallback process, the MME compiles the S1AP message (UE CONTEXT MODIFICATION REQUEST) including the CS Fallback Indicator and sends it to the eNB. The eNB sends an adequate response message (UE CONTEXT MODIFICATION RESPONSE) for step 2) to the MME.

4)

If the measurement result is required for processing the CS Fallback, the eNB can request the UE to take measurement of the target RAT (optional).

5)

To request the CS Fallback processing from the UTRAN, the eNB uses the Redirection procedure. The eNB includes the redirectedCarrierInfo for the target UTRAN in the RRC CONNECTION RELEASE message and sends it to the UE. The UE carries out


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Step

Description redirection, according to the redirectedCarrierInfo required by the eNB, to the UTRAN.

6)

The eNB transmits the UE CONTEXT RELEASE REQUEST message to the MME.

7)

The MME carries out the procedure for releasing the UE context of the E-UTRAN.

8)

After connecting to the UTRAN, the UE sends the RRC INITIAL DIRECT TRANSFER message to set the CS signaling connection. If the LA or RA of the UTRAN cell connected is different from the stored information, the location registration procedure (LAU and/or RAU or combined LAU/RAU) is performed.

9)

After receiving the UE CONTEXT RELEASE REQUEST message in step 6, the MME carries out the suspension processing of the non-GBR bearer(s) of the S-GW/P-GW and the deactivation processing of the GBR bearer(s). Afterward, the MME manages the UE context in the suspended status.

10)

The UE transmits the CM SERVICE REQUEST message to the UTRAN to carry out next procedure for the CS call setup.

CS Fallb ack t o GERAN

Below is the message flow for the CS Fallback procedure from the E-UTRAN to the GERAN. The procedure below shows that the CS Fallback procedure is carried out through cell change order processing to the GERAN without PS HO when UE, which is in RRC Connected state, sends the CS call.

UE

Source eNB

Target BSS


MME

S/P-GW

MSC

SGSN


UL INFORMATION TRANSFER/ULNAS TRANSPORT (Extended Service Request) 2)

S1AP request message

With CS Fallback indicator 3) S1AP response message ) 5)

measuremen solicitation(Optional) Mobility from EUTRA Command 6)

UE CONTEXT RELEASE REQUEST 7)

8)

S1 Release

UE changes RATthen LAU or Combined RA/LA update orRAU or LAU and RAU 9)

Suspend 10) SUSPEND REQUEST/RESPONSE 11) Update bearer(s)

12) RRC/Iu-CS messages (CM Service Request) CS Call Setup

Figure 32. CS Fallback to GERAN Procedure (UE in Active mode, No PS HO support)


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Step 1)

Description In the E-UTRAN, when the UE in RRC Connected state requests CS call setup, the UE creates the EXTENDED SERVICE REQUEST message (NAS) including the CS Fallback Indicator and sends it to the network. The RRC UL INFORMATION TRANSFER message is used for this. The eNB uses the UL NAS TRANSPORT message for relaying it to the MME.

2)-3)

In order to request the eNB for CS Fallback process, the MME compiles the S1AP message (UE CONTEXT MODIFICATION REQUEST) including the CS Fallback Indicator and sends it to the eNB. The eNB sends an adequate response message (UE CONTEXT MODIFICATION RESPONSE) for step 2) to the MME.

4)

If the measurement result is required for processing the CS Fallback, the eNB can request the UE to take measurement of the target RAT (optional).

5)

The eNB uses the Cell Change Order procedure for the CS Fallback processing to the GERAN. The eNB includes the PCI corresponding to the GERAN target cell and carrierFreq in the MOBILITY FROM E-UTRA COMMAND message and sends it to the UE. The UE carries out the cell change order procedure on the GERAN target cell specified by the eNB.

6)

The eNB transmits the UE CONTEXT RELEASE REQUEST message to the MME.

7) 8)

The MME carries out the procedure for releasing the UE context of the E-UTRAN. After connecting to the GERAN, the UE carries out the RR connection setup procedure. If the LA or RA of the connected GERAN cell is different from the stored information, the location registration procedure (LAU and/or RAU or combined LAU/RAU) is carried out.

9)-10)

When the UE or the target GERAN cell does not support the Dual Transfer Mode (DTM), the UE starts the Suspend procedure. When the Suspend request is received from the UE, the SGSN processes the Suspend Request/Response procedure with the MME.

11)

The MME carries out the suspension processing for the non-GBR bearer(s) of the SGW/P-GW and the deactivation processing of the GBR bearer(s). The MME subsequently manages the UE context in the suspended state.

12)

The UE transmits the CM SERVICE REQUEST message to the UTRAN to carry out next procedure for the CS call setup.


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4.2

Data Traffic Flow Sendin g Path

The user data received from the EPC passes through the network interface module and is transmitted through the Ethernet switch to the CDU. The transmitted user data goes through baseband-level digital processing before being configured for the CPRI, and then E/O converted. The converted signal is transmitted to through the optic cable to the remote RRU. The RRU does O/E conversion for a received optic signal. The converted baseband signal from the wideband is converted into an analog signal and transmitted through the highpower amplifier, filter and antenna. Receiving Path

The RF signal received by the antenna goes through the RRU filter and low-noise amplification by the LNA. The RF down-conversion and the digital conversion are performed for this signal, and the signal is then converted to a baseband signal. It is configured for the CPRI, and goes through the E-O conversion again. The converted signal is transmitted to through the optic cable to the CDU. The data for which the SC-FDMA signal processing is carried out in the CDU is converted to the Gigabit Ethernet frame and transmitted from the CDU to the EPC via the GE/FE.

RRU CDU

GE/FE

r o s in s a e c Mo r P

l e n d n r a a h C C

I R P C

n o i rs e v n o c

O/E

E/O

I R P C

O/E

E/O

EPC Optic CPRI

n io s r e v n o c

DDC/

A/D

UP/

DUC

D/A

Down

DDC/

A/D

UP/

PA LNA PA

DUC

D/A

Down

DDC/ DUC

A/D D/A

UP/ Down

PA

DDC/

A/D

UP/

PA

DUC

D/A

Down

LNA

LNA

LNA

TDD Switch. TDD Switch. TDD Switch. TDD Switch.

BPF

BPF

BPF

BPF

Figure 33. Data Traffic Flow


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4.3

Netw or k Sync Flow The eNB uses GPS for synchronization. The CDU’s UCCM is the GPS receiving module. It receives synchronization signal from the GPS, creates and distributes clocks.

SYS (System Clock 30.72 MHz) SFN (System Frame Number) Control

PP2S (Even Clock)

Clock Generation & Distribution

1 PPS

CDU

Digital 10 MHz PP2S (Even Clock)

GPS UCCM

Analog 10 MHz

Test equipment

Figure 34. Network Synchronization Flow


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4.4

Alarm Sig nal Flo w An environmental fault or hardware mount/dismount is reported with an alarm signal, which is collected by the UAMA of the CDU, and then reported to the LTE System Manager (LSM). The operator can also provide custom alarms through the UDA. The following alarms are collected by the UAMA:

Al arm Type Function Fail Alarm

Remark s

Ap pl ic abl e

Fault alarm due to software/hardware problems

L9CA

defined as ‘Function Fail’ Power Fail Alarm

Fault alarm due to power problems

L9CA

Deletion Alarm

System report alarm due to hardware mount/dismount

L9CA

UDA

Alarm that the operator wants to provide

UAMA

RF Unit Alarm

RF unit alarm

RRU

C

LSM

A

B

RRU (8) L9CA (0)

. . .

UAMA

GPS Module(in UAMA) RRU (0)

A

: Reset

B

: Alarm

C

: Remote Pattern Reset

Figure 35. Alarm flow


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4.5

Loadin g Flow Loading is the procedure through which the processors and devices of the system can download from the LSM the software executables, data, and other elements required to perform their functions. Loading the system is performed during the system initialization procedure. Loading is also involved when a specific board is mounted in the system, when a hardware reset is carried out, or when the operator of an upper management system restarts a specific board. At the first system initialization, the system is loaded through the LSM. As the loading information is stored in the internal storage, no unnecessary loading is carried out afterward. After the first system initialization, it compares the software files and versions of LSM and downloads changed software files. The loading information contains the software image and default configuration information file, etc.

eNB Master OAM Board

LSM

Sub Processor

Figure 36. Loading Signal Flow


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4.6

Operati on and Main tenance Message Flow The operator can check and change the status of the eNB through the management system. To accomplish this, the eNB provides the SNMP agent function, and the LSM operator can carry out the operation and maintenance functions of the eNB remotely through the SNMP. Moreover, the operator can carry out the maintenance function based on the Web-EMT in the console terminal using the web browser. After connecting to telnet or SSH, the maintenance function can be carried out through the CLI. The statistical information provided by the eNB is given to the operator in accordance with the collection interval. The operation and maintenance in the eNB is performed using the SNMP message between the SNMP agent in the main OAM and the SNMP manager of the LSM. The eNB processes various operation and maintenance messages received from the SNMP manager of the management systems, then transmits their results to the SNMP manager, and reports events such as faults and status changes to the SNMP manager in real-time. The figure below shows the operation and maintenance signal flow.

Web-EMT (HTTP Client)/CLI

LSM (SNMP Manager)

eNB Master OAM Board HTTP Server CLI

SNMP

Other Blocks

SNMP message HTTP message (command/response) CLI command Statistical Data

Figure 37. Operation and Maintenance Signal Flow


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5.0 CHAPTER 5. Supplementary Functio ns and Tools

CHAPTER 5. Supplementary Func tio ns a nd T ool s

5.1

Web-EMT The Web-EMT is a kind of GUI-based console terminal. It is the tool that monitors the status of devices and performs operation and maintenance tasks by connecting directly to the eNB. The operator can run the Web-EMT using Internet Explorer, without installing separate software. The GUI is provided using the HTTPs protocol internally.

Web-EMT

HTTP message

HTTP message

eNB

eNB

Master OAM Board

Master OAM Board

HTTP Server

HTTP Server OAM command/ response

OAM command/ response Other Blocks

…

Other Blocks

Figur e 38. Web-EMT Interface

Through the Web-EMT, the operator can reset or restart the eNB or its internal boards, view and change the configuration and operation parameter values, monitor the system status and faults, carry out diagnostic functions, and so on. But the resource grow and degrow functions and changing the operation information related to neighbor list are available from the LSM only, which manages the entire networks and the loading images.


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Ver. 5.0 CHAPTER 5. Supplementary Functi ons and Tools

5.2

CLI The CLI is the method used for operation or maintenance of the eNB. You can log in to the eNB through telnet via the PC accessible through eNB Ethernet so as to perform the textbased operation and maintenance using the CLI. The functions of the CLI are as follows: Loading

The CLI provides the function that loads a program necessary for the eNB. Therefore, the CLI can initialize the eNB normally without synchronizing with the LSM and can load a specific device selectively. It can also reset or restart each board of the eNB. Configuration Management

The CLI provides the function that executes the Man-to-Machine Command (MMC) that allows viewing and changing the configuration information for eNB. Status Management

The CLI provides the function that manages the status for the processors and various devices of the eNB. Fault Management

The CLI checks whether there are any faults with the processors and various devices of the eNB and provides the operator with the location and log of each fault. Since the CLI can display both of the hardware and software faults, the operator can know all faults that occur in the eNB. Diagnosis and Test

The CLI provides the function that diagnoses the connection paths, processors, and various devices that are being operated in the eNB, and provides the test function that can detect a faulty part. The major test functions that the CLI can perform include measuring the transmitting output and the antenna diagnosis function, etc.


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5.0 CHAPTER 5. Supplementary Functio ns and Tools

5.3

RET The eNB can support the RET function through connection to the antenna and RRU which satisfy the AISG 2.0 interface. To provide the RET function, the eNB transmits/receives the control messages to/from the LSM through the RET controller within the UAMA and the CPRI path of CPRI FPGA. By using this path, the LSM can carry out the RET function that controls the antenna tilting angle remotely. In addition, for the RET operation, the RRU provides power to every antenna connected to it.

LMS (SNMP Manager) Antenna(A ISG in ter fac e) R E T

RRU(0)

CDU UAMA

M o t o r

RET Relay

RET Controller

R E T

RRU(1)

M o t o r

RET Relay

R E T

RRU(2)

RET Relay

CPRI

. . .

RS-485 and Power

M o t o r

Antenna Antenna Antenna Antenna



. . .

Figur e 39. RET Interface


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Ver. 5.0 AB BREVIA TION

ABBREVIATION

3GPP

3rd Generation Partnership Project

64 QAM

64 Quadrature Amplitude Modulation

AC

Admission Control

ACL

Access Control List

ADC

Analog to Digital Converter

AKA

Authentication and Key Agreement

AISG

Antenna Interface Standards Group

AM

Acknowledged Mode

AMBR

Aggregated Maximum Bit Rate

ANR

Automatic Neighbor Relation

ARQ

Automatic Repeat Request

AS

Access Stratum

BGP

Border Gateway Protocol

BSS

Base Station System

C&M

Control & Management

CC

Chase Combining

CDD

Cyclic Delay Diversity

CDU

Cabinet DU

CFR

Crest Factor Reduction

CLI

Command Line Interface

CM

Configuration Management

CoS

Class of Service

CP

Cyclic Prefix

CPLD

Complex Programmable Logic Device

CPRI

Common Public Radio Interface

CPS

Call Processing Software

CRS

Cell-specific Reference Signal

CS

Circuit Service

CSAB

CPS SON Agent Block

CSL

Call Summary Log

CSM

Core System Manager

A

B C


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5.0 AB BREVI ATION

D DAC

Digital to Analog Converter

DBMS

Database Management System

DD

Device Driver

DDC

Digital Down Conversion

DFT

Discrete Fourier Transform

DHCP

Dynamic Host Configuration Protocol

DiffServ DL

Differentiated Services Downlink

DSCP

Differentiated Services Code Point

DTM

Dual Transfer Mode

DU

Digital Unit

DUC

Digital Up Conversion

DUS

Debugging Utility Service

ECCB

eNB Call Control Block

ECMB

eNB Common Management Block

ECS

eNB Control processing Subsystem

EDS

eNB Data processing Subsystem

eMBMS

enhanced/evolved Multimedia Broadcast Multicast Services

EMC

Electromagnetic Compatibility

EMI

Electromagnetic Interference

EMS

Element Management System

eNB

evolved UTRAN Node B

E

ENS

Event Notification Service

E/O

Electric-to-Optic

EPC

Evolved Packet Core

EPS

Evolved Packet System

ES

Energy Saving

E-UTRAN

Evolved UTRAN

F FANM

Fan Module

FE

Fast Ethernet

FHS

File-system Hierarchy Standard 2.2

FM FSTD

Fault Management Frequency Switched Transmit Diversity

FTP

File Transfer Protocol


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AB BREVIA TION

G GBR

Guaranteed Bit Rate

GE

Gigabit Ethernet

GPRS

General Packet Radio Service

GPS

Global Positioning System

GTP

GPRS Tunneling Protocol

GTPB

GPRS Tunneling Protocol Block

GTP-U GW

GTP-User Gateway

HARQ

Hybrid Automatic Repeat Request

H HAS

High Availability Service

HO

Handover

HSS

Home Subscriber Server

HTTP

Hypertext Transfer Protocol

HTTPs

Hyper Text Transfer Protocol over SSL

ICIC

Inter-Cell Interference Coordination

ICMP

Internet Control Message Protocol

IDFT IETF

Inverse Discrete Fourier Transform Internet Engineering Task Force

IF

Intermediate Frequency

IP

Internet Protocol

IPRS

IP Routing Software

IPSS

IP Security Software

IPv4

Internet Protocol version 4

IPv6

Internet Protocol version 6

IR

Incremental Redundancy

L9CA

LTE eNB Channel card board Assembly

LNA

Low Noise Amplifier

LSM

LTE System Manager

LTE

Long Term Evolution

MAC

Media Access Control

MACB

Medium Access Control Block

I

L

M MBMS GW

MBMS Gateway

MBR

Maximum Bit Rate

MBSFN

MBMS over a Single Frequency Network

MCCH

Multicast Control Channel


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5.0 AB BREVI ATION

MCE

Multi Cell Multicast Coordination

MCH

Multicast Channel

MCS

Modulation Coding Scheme

MDS

Message Delivery Service

MFS

Miscellaneous Function Service

MIB

Master Information Block

MIMO

Multiple-Input Multiple-Output

MMC

Man Machine Command

MME

Mobility Management Entity

MSS

Master SON Server

MTCH

Multicast Transport Channel

MU

Multiuser

NAS

Non-Access Stratum

NE

Network Element

NP

Network Processing

NPC

Network Processing Control

NR

Neighbor Relation

NRT

Neighbor Relation Table

OAM

Operation and Maintenance

OCNS

Orthogonal Channel Noise Simulator

N

O OCS

Online Charging System

O/E

Optic-to-Electric

OFCS

Offline Charging System

OFD

Optic Fiber Distributor

OFDMA

Orthogonal Frequency Division Multiple Access

OS

Operating System

OSAB

OAM SON Agent Block

OSPF

Open Shortest Path First

OSS

Operating Support System

PAPR

Peak-to-Average Power Ratio

PCI PCRF

Physical Cell Identity Policy and Charging Rule Function

P

PDCB

PDCP Block

PDCP

Packet Data Convergence Protocol

PDN

Packet Data Network

PDPU

Power Distribution Panel Unit

PDU

Protocol Data Unit

P-GW

PDN Gateway

PLER

Packet Loss Error Rate


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Q

PM

Performance Management

PMCH

Physical Multicast Channel

PMI

Precoding Matrix Indicator

PMIP

Proxy Mobile IP

PRACH

Physical Random Access Channel

PRB

Physical Resource Block

PSS

Primary Synchronization Signal

QCI

QoS Class Identifier

QoS

Quality of Service

QPSK

Quadrature Phase Shift Keying

RACH

Random Access Channel

RB

Radio Bearer

RB

Resource Block

RECS-B2

Rectifier System-B2

RET

Remote Electrical Tilt

RF

Radio Frequency

RFS

Root File System

RLC

Radio Link Control

RLCB

Radio Link Control Block

RO RRC

RACH Optimization Radio Resource Control

RRU

Remote Radio Unit

RU

Radio Unit

S1-AP

S1 Application Protocol

SC

Single Carrier

SC-FDMA

Single Carrier Frequency Division Multiple Access

SCTB

Stream Control Transmission protocol Block

SCTP

Stream Control Transmission Protocol

SDU

Service Data Unit

SFBC

Space Frequency Block Coding

SFN

System Frame Number

SFTP

SSH File Transfer Protocol

S-GW

Serving Gateway

SIBs SM

System Information Blocks Spatial Multiplexing

SMC

Security Mode Command

SMS

Short Message Service

SNMP

Simple Network Management Protocol

SON

Self Organizing Network

SPD

Surge Protect Device

SSH

Secure Shell

SSS

Secondary Synchronization Signal

STBC

Space Time Block Coding

R

S


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5.0 AB BREVI ATION

SU


Single User

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SwM

Software Management

SYNC

Synchronization

TA

Tracking Area

T TCE

Trace Collection Entity

TDD

Time Division Duplex

THS TM

Task Handling Service Test Management

TMGI

Temporal Mobile Group ID

TOD

Time Of Day

TrM

Trace Management

UADB

Universal platform type A Digital Backplane board assembly

UAMA

Universal platform type A Management board Assembly

UCCM

Universal Core Clock Module

UDA

User Defined Alarm

UDE

User Defined Ethernet

UDP

User Datagram Protocol

UE

User Equipment

UL

Uplink

UTRAN

UMTS Terrestrial Radio Access Network

VLAN

Virtual Local Area Network

VSWR

Voltage Standing Wave Ratio

Web-EMT

Web-based Element Maintenance Terminal

U

V

W


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LTE eNB

System Description ©2012~2013 Samsung Electronics Co., Ltd. All rights reserved. Information in this manual is proprietary to SAMSUNG Electronics Co., Ltd. No information contained here may be copied, translated, transcribed or duplicated by any form without the prior written consent of SAMSUNG. Information in this manual is subject to change without notice.


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