Nsn 2g Gsm Basics

2G - GSM Global System for

Mobile • Catarina Ferreira • 18-05-2015

Basics for newcomers 1 © Nokia Solutions and Networks 2015

2

Introduction

BSC Hardware and Functionality

BSS Overview

Flexi Multiradio BTS

BSS Radio Network

Abis and MML

Basic Call Procedures

Commissioning

© Nokia Solutions and Networks 2015

Introduction GSM stands for Global System for Mobile communications and is applied as standard for mobile networks in many countries today. The first systems were implemented 50 years ago (1G, first generation): • • •

Limited mobility Handsets bulky Expensive

Introduction of GSM (2G, second generation) in the 90’s: • • • • •

Unlimited mobility within a network Wide International coverage Messaging Mobile Internet Mobile Solutions

Introduction of messaging services: • •

SMS (Short Messaging Service) MMS (Multimedia Messaging Service)

3 © Nokia Solutions and Networks 2015

Structure With GSM you can move within the whole network without service interruption. All mobile networks have basically the same structure and are composed of two parts: -

The Core Network controls your call, transmits your voice calls and data, and forwards it to external networks, e.g. other telephone networks or the Internet.

-

The Radio Network provides the user access to the network. The user can access the network using his mobile device to connect to the nearest antenna. • •

Consists of many of these antennas (BTS, Base Station Transceiver) and several Base Station Controllers (BSC) controlling those antennas. The Base Station Controllers provide the connection from the mobile device to the Core Network.


To perform a phone call, you need a Mobile Equipment (ME) and a SIM card (Subscriber Identity Module). The SIM card and the Mobile Equipment make up the Mobile Station (MS) of the GSM network. The SIM is comparable to an identity card, containing all relevant user data and information used for encryption and authorization checks by the network. It contains the International Mobile Subscriber Identity (IMSI), which uniquely identifies the user on a worldwide basis. The IMSI is used for internal processes in the network.


To be able to use your mobile phones there is a frequency range on the Radio Interface, called frequency bands. Four different frequency bands are used at the moment: • • • •

850 MHz (GSM-R, rail communications) 900 MHz (GSM) 1800 MHz (DCS, Digital Cellular Service) 1900 MHz (PCS, Personal Communication Services)

The lower the frequency band, the higher the range of a cell.


Originally, GSM was mainly intended to transport voice as a so-called circuit switched service, a fixed connection is established and a fixed amount of bandwidth is reserved during the whole call which cannot be used by other subscribers. In order to place a phone call, a connection has to be established on the Radio Interface from the mobile phone to the Radio Network, a so-called channel. There are 8 channels per radio frequency. The number of channels a single antenna can serve depends on the number of frequencies it possesses.

The Radio Networks provides access to the users’ mobiles via several antennas or BTS (Base Transceiver Stations). Each antenna serves a specified area, which is called a cell or sector.


The antennas are positioned in such a way that adjacent cells overlap at their borders to provide an uninterrupted connection by connecting the closest antenna.

The Base Stations and their antennas are controlled by their respective Base Station Controller (BSC). The BSC collects the traffic of its corresponding Base Stations and forwards this traffic to the Core Network. It also performs controlling tasks for the connections. The GSM Core Network consists of the Mobile Switching Center (MSC that switch the phone calls through the network ) and several databases. MSCs which provide access to external telephone networks are called Gateway MSCs. Besides routing the phone calls, the MSC is also responsible for user management when performing a phone call and billing information. 8 © Nokia Solutions and Networks 2015

In order to perform all tasks regarding user management, the MSC needs access to all relevant information. This information is stored in different Databases belonging to the Core Network: • • •

The subscriber phone number which corresponds to the Mobile Subscriber Identity (IMSI) Charging information about the user and accessible services for the user Where the user is located in order to route an incoming call.

One important feature of GSM is the unlimited mobility maintaining a call. The call is not interrupted when moving from the coverage area of one cell to another. The call has been handed from one cell to another – this process is called a handover.


Summary GSM is the first mobile network truly reaching the masses. Unlimited mobility within the network, international coverage, Messaging services, Mobile Internet, and Mobile Solutions make GSM a part of daily life. The GSM network consists of the following parts: •

Mobile Station – Mobile phone and the SIM Card

•

Radio Network – enabling access for the mobile phones to the Core Network

•

Core Network – switching tasks and call handling

Three basic procedures illustrate the principle of GSM: •

Location Update – informing the Core Network about the location of the user

•

Call Setup – locating the user and establishing a connection

•

Handover – providing mobility while making a call


GPRS General Packet Radio Service GSM was mainly intended for voice services. To increase the data rate in existing GSM networks, GPRS (General Packet Radio Service) was introduced. GPRS is the link to 3G, therefore it is also called 2.5G. GPRS provides access to the Internet and other data services for mobile users. GPRS features: • • • •

Higher data transmission rates Charging flexibility "Always on" functionality Enhanced applications and services


Classical phone networks are so called circuit switched networks: • • •

Each user establishes a “circuit” or channel when setting up the call The allocated resources are exclusively reserved for the individual user for the entire duration of the call These individually allocated channels are dedicated channels.

GPRS introduces a more efficient way of data transmission. These connections are packet data oriented, data is segmented and transmitted in small data packets. • •

GSM offers minimum uplink data rates 9.6 kbit/s GPRS offers a theoretical maximum uplink data rate up to 40.0 kbit/s.

In order to obtain higher data rates several data channels can be bundled and used simultaneously by one or several users.


The data transmission channels can be classified in two types: • •

Data channels transporting data packets from the mobile phone to the network are called “uplink channels”. Data channels transporting data packets from the network to the mobile phone are called “downlink channels”.

GPRS supports transmission rates of 9.6, 13.4, 15.6, and 21.4 kbits for each data channel accordingly to the channel quality. • •

GSM offers minimum uplink data rates 9.6 kbit/s GPRS offers a theoretical maximum uplink data rate up to 40.0 kbit/s.


The mobiles are classified by its so called “multislot class” and nowadays mostly in use are class 10 which means that they support up to 5 channels: • • • • •

2 channels in the uplink and 3 in the downlink 1 channel in the uplink and up to 4 channels in the downlink can receive up to 21.4 kbits on each channel maximum data rate of 85.6 kbits when bundling 4 channels in the downlink 42.8 kbits when bundling two channels in the uplink.

All mobile networks have basically the same structure and are composed of two parts: •

•

The Core Network controls your call, transmits your voice calls and data, and forwards it to external networks, such as other telephone networks or the Internet. The Radio Network provides the user access to the network from the mobile devices. The Radio Network consists of many BTS and BSC.

To upgrade a GSM network to support GPRS, regarding Radio Network, only a software upgrade and a single module in the BSC is necessary (less expensive solution than 3G). However, a new Core Network is required to handle the data packets in GPRS: • •

Serving GPRS Support Node – SGSN Gateway GPRS Support Node – GGSN


The SGSN is responsible for the management of the data traffic of all users within a certain geographical area. • • • •

authentication of users switching of data traffic storing of charging information encrypting the data connection with the mobile

The GGSN acts as gateway between the GPRS network and the Internet and other external data networks.

EDGE Enhanced Data for GSM Evolution The performance and data rate of GSM can be further enhanced with the introduction of EDGE (Enhanced Data for GSM Evolution). When applied to GPRS, EDGE is referred to as E-GPRS. E-GPRS offers a variety of benefits: • • •

Significantly increased data rates compared to GPRS Higher capacity of the network Based on the existing GPRS infrastructure

Whereas GPRS offers maximum data rates of up to 40.0 Kbit/s, EGPRS offers up to 236.8 Kbit/s. That means E-GPRS offers data rates for single users which are high enough to enable services which normally are only possible with 3G systems.


E-GPRS is based on GPRS, it combines up to eight channels and almost triples the data rate by transporting three bits at a time instead of one bit. Only minor changes are necessary in the GPRS network to support EDGE: •

• •

On the hardware side the transceivers in the Base Station, which are responsible for transforming the bits into a waveform, are affected by EDGE. That means the network operator has to deploy transceivers, which support EDGE. Otherwise, only a software upgrade is necessary in order to support EDGE.


Summary GPRS is a technology which enables mobile Internet access and use of mobile data services. GPRS achieves much higher data transfer speeds than original GSM because : • • • •

GPRS GPRS GPRS GPRS

provides higher bit-rates per channel lets subscribers use more than one channel in parallel lets subscribers share channels transmits data in packets rather than setting up connections

Sharing of channels means subscribers can get access when they need it rather than waiting for channels to become free. Because GPRS is packet based, users can enjoy "always on" access to the Internet and charging is based on the volume of data transferred rather than on connection times. GPRS is the bridge to high speed 2.5G, 3G and 4G services from Operators and Internet-based service providers. EDGE is an upgrade for existing GPRS networks, providing distinctly higher data rates up to 236.8 Kbit/s. Therefore it is also called EGPRS. Only minor changes are necessary in existing GPRS networks to perform an upgrade to EGPRS, so is an inexpensive way to provide coverage with higher data rates in regions which are not yet covered by UMTS. The main difference between GPRS and EGPRS lies within the used modulation: EGPRS carries three bits at a time compared to one bit in GPRS. Consequently, the data rate is almost tripled.

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Exercise

18


Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

19


GSM Subsystems The GSM network is functionally divided into four elements: • • • •

Base Station Subsystem (BSS) is one of the main functional elements of the GSM network. The Network Switching Subsystem (NSS) GPRS Core Network to SGSN (Packet Core) Operation and Support System (OSS) or Network Service and Management Subsystem (NMS), provided by NetAct.

The actual network needed for establishing calls is composed by the NSS and the BSS. The BSS is responsible for radio path control and every call is connected through the BSS . The NSS takes care of call control functions. Calls are always connected by and through the NSS. The OSS is the operation and maintenance related part of the network and it is needed for the control of the whole GSM network. The network operator observes and maintains network quality (KPIs) and service offered through the OSS. 20


Operation and Support System (OSS) The purpose of the OSS is to monitor various functions and elements of the network. The operator workstations are connected to the database and communication servers via a Local Area Network (LAN). The database server stores the management information about the network. These communications are carried over a Data Communications Network (DCN), which connects to the OSS via a router. The functions of the OSS can be divided into three categories: • • •

Fault management Configuration management Performance management

These functions cover the whole of the GSM network elements from the level of individual BTSs, up to MSCs and Databases.


Network Switching Subsystem (NSS) NSS or Core Network is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations. The main functions of NSS are: • •

• • •

Call control: This identifies the subscriber, establishes a call, and clears the connection after the conversation is over. Charging: This collects the charging in formation about a call (the numbers of the caller and the called subscriber, the time and type of the transaction, etc.) and transfers it to the Billing Centre. Mobility management: This maintains information about the subscriber’s location. Signaling: This applies to interfaces with the BSS and PSTN. Subscriber data handling: This is the permanent data storage in the HLR and temporary storage of relevant data in the VLR.


Network Switching Subsystem (NSS) The NSS originally consisted of the circuitswitched core network, used for traditional GSM services such as voice calls, SMS, and circuit switched data calls. It was extended with an overlay architecture to provide packet-switched data services known as the GPRS core network. This allows mobile phones to have access to services such as WAP, MMS, and the Internet. The Switching Core Network (SCN) comprises network elements that implement CS services (e.g. voice calls), like Multimedia Gateway (MGW), Mobile switching centre server (MSS). Packet Core Network (PCN), on the other hand, supports PS data connections to external networks (e.g. Internet). 23 © Nokia Solutions and Networks 2015

Network Switching Subsystem (NSS) The Network Switching Subsystem (NSS) contains the network elements MSC, VLR, HLR, AC and EIR.

HLR (Home Location Register): • •

MSC (Mobile services Switching Centre): • • • •

controlling calls in the mobile network identifies the origin and destination of a call as well as the type of a call Is the initiation of paging which is the process of locating a particular mobile station in case of a mobile terminated call (a call to a mobile station) charging data collection.

VLR (Visitor Location Register): is a database which contains: •

• •

information about subscribers currently being in the service area of the MSC/VLR (identification numbers, authentication of the SIM and ciphering, services that can be used) When a mobile station comes to a new MSC/VLR serving area, it must register itself in the VLR, registering and updating its location The VLR database is temporary.


•

permanent register of the subscribers keeps track of the current location of its customers. The MSC asks for routing information from the HLR if a call is to be set up to a mobile station Authentication Centre (AC) and Equipment Identity Register (EIR), are located in the HLR.

AC (Authentication Centre): • •

provides security information to the network, so that we can verify the SIM cards authentication between the mobile station and the VLR, and cipher the information transmitted between the MS and the Base Transceiver Station (air interface).

EIR (Equipment Identity Register): • • •

used for security reasons is responsible for IMEI checking (checking the validity of the mobile equipment) is an optional procedure, so it is up to the operator to define if and when IMEI checking is performed. (Some operators do not even implement the EIR at all.)


GPRS Network Elements The GPRS system brings some new network elements to an existing GSM network. These elements are:

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•

Packet Control Unit (PCU)

•

Serving GPRS Support Node (SGSN): the MSC of the GPRS network

•

Gateway GPRS Support Node (GGSN): gateway to external networks

•

Charging Gateway (CG)

•

Domain Name System (DNS)

•

Firewalls: used wherever a connection to an external network is required.



Base Station Subsystem (BSS) The Base Station Subsystem is responsible for managing the radio network and it is controlled by an MSC. The main function of the BSS is to connect the subscriber's mobile station (MS) to the GSM network and provide connections to the mobile switching centre (MSC), and to GPRS core network, serving GPRS support node (SGSN). The BSS also takes care of the mobility management of the cellular network including, for example, handover management and various measurements. Tasks: •

•

Radio path control: The BSS is the part of the network taking care of radio resources, that is, radio channel allocation and quality of the radio connection.

Synchronization: The BSS uses hierarchical synchronization, (MSC synchronizes the BSC, and the BSC further synchronizes the BTSs associated with that particular BSC). Inside the BSS, synchronization is controlled by the BSC. If the synchronization chain is not working correctly, calls may be cut or the call quality may 28 © Nokia not be the bestSolutions possibleand orNetworks even be2015 impossible to establish a information call.

•

Air and A interface signaling: In order to establish a call, the MS must have a connection through the BSS.

•

Connection establishment between the MS and the NSS: The BSS is located between two interfaces, the air- and the A-interface. The MS must have a connection through these two interfaces before a call can be established. Generally speaking, this connection may be either a signaling connection or a traffic (speech, data) connection.

•

Mobility management and speech transcoding: BSS mobility management mainly covers the different cases of handovers.

The BSS consists of the following elements: • BSC - Base Station Controller • BTS - Base Transceiver Station • TC – Transcoder

BSS Network Elements The BSC (Base Station Controller) is the central network element of the BSS and it controls the radio network. Main tasks: • • • • •

Connection establishment between the MS and the NSS Mobility management Statistical raw data collection Air- and A-interface signaling support BTS and TC control

The BTS (Base Transceiver Station) is the network element responsible for maintaining the air interface and minimizing the transmission. The BTS parameters in BSC handle the following major items: what kind of handovers (when and why), paging organization, radio power level control, and BTS identification. Most important tasks: • • •

Air Interface signaling Ciphering Speech processing


TC(SM) – Transcoder (SubMultiplexer) In the air interface, the media carrying the traffic is a radio frequency. To enable an efficient transmission of digital speech information over the air interface, the digital speech signal is compressed. We must however also be able to communicate with and through the fixed network, where the speech compression format is different. Somewhere between the BTS and the fixed network, we have to convert from one speech compression format to another.

Transcoder Encoding and Decoding According to GSM 900 and GSM 1800 specifications, the bit rate in the air interface is 13 Kbits/s (full rate, enhanced full rate) and the bit rate in the Mobile services Switching Centre (MSC) and PSTN interface is 64 Kbits/s.

The actual hardware that does the conversion from 13 Kbits/s to 64 Kbits/s and vice versa is called a transcoder. The transcoder belongs to the BSS and it can be placed between the BSC and the MSC or in the MSC (MGW). A transcoder used in conjunction with a submultiplexer makes it possible to multiplex traffic channels from four PCM lines, thereby reducing transmission costs.

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BSS Network Elements Base Station Controller, BSC • • • • • • • • • •

terrestrial channel management configuration and management of traffic channels frequency hopping control Paging BTS and MS power control idle channel quality monitor quality and field strength control for active channels handover control maintenance of BTS / BSC / TC interfaces to the OSS / BTS / TC / SGSN

Transcoder, TCSM • • • • • •

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considered as part of the BSC normally at the MSC site used for converting the bit rate of traffic channels between 64 and 16 Kbit/s speech activity detection framing and synchronization of the vocoder block interfaces to the MSC / BSC


Base Transceiver Station, BTS • • • • • • • • • • •

timing Broadcast Control Channels (BCCH) and Common Control Channels (CCCH) forwarding MS and BTS measurements to the BSC detecting RACHs (Random Access Channels) from the MS channel coding and decoding on the radio path interleaving and de-interleaving on the radio path encryption and decryption on the radio path performing frequency hopping GMSK modulation, demodulation, up / down conversion and power amplifying transmitter RF signal combining receiver RF signal filtering, amplifying and multicoupling reporting idle traffic channel quality to the BSC

Transmission Unit TRU • •

provides Abis interface reallocates the Traffic and signaling channels in the BTS

BSS Interfaces A Interface – Legacy • • •

Located between the MSC or MGW and the BSC. It is used for carrying traffic channels and the BSSAP user part of the SS7 stack. Between the MSC and the TCSM, a physical A interface used to consist of PCM lines or optical lines between network elements. With the introduction of the AoIP, the A-interface between BSC and MGW can also be based on IP/Ethernet.

Ater Interface – Legacy • • •

The Ater interface connects the TCSM to the BSC and carries the compressed / multiplexed speech channels. A physical interface consists of PCM lines, packet network (PWE CESoPSN) or TDM optical lines between network elements. Packet Ater interface is an IP based BSS internal interface between the Multicontroller BSC and Multicontroller Transcoder (mcTC).


BSS Interfaces Abis Interfaces • • • • •

Is a closed interface between the BTS and the BSC The physical interface used can be a PCM line or Ethernet. Uses TDM sub-channels for traffic (TCH), LAPD protocol for BTS supervision and telecom signalling, and carries synchronization from the BSC to the BTS and MS. Packet Abis makes possible to use higher bandwidth and IP based transmission between BTS and BSC. The Abis operation and maintenance (O&M) part supports alarm consistency, remote transmission equipment management, and BTS database management. Signalling on Abis interface: LAPD, OMUSIG, TRXSIG

Abis Transport Concept: Packet Abis over TDM: PCM is used for transport (IP over Circuit Switched Network) Packet Abis over Ethernet: Ethernet is used for transport (IP over Packet Switched Network). Legacy Abis over TDM / Ethernet: PCM or PCM over Ethernet (CESoPSN) is used for transport


BSS Interfaces Gb Interface Is an open interface between a BSC and a Serving GPRS Support Node (SGSN) in the GPRS Core network. It may be implemented using Frame Relay (FR) or IP transmission. Frame Relay Options The Frame Relay can be either point-to-point (PCU – SGSN) or there can be a Frame Relay network located between the BSC and the SGSN.

A Gb interface Bearer channel can use 1 to 31 64kbit/s timeslots. The following figure displays examples of the Gb interface transmission solutions: 1) Spare capacity of the Ater and the A interfaces is used for the Gb interface. The Gb timeslots are transparently through connected in the TCSM and in the MSC 2) A transmission network provides a point-to-point connection between the BSC and the SGSN. 3) A Frame Relay network is used 4) The BSC and the SGSN are connected via an IP Network - Gb over IP Connection 34 © Nokia Solutions and Networks 2015

BSS Interfaces The traffic channels in the Air interface are allocated into a TDMA frame. The TDMA frame consists of 8 The open-air interface between the MS and the BTS. time slots. Timeslot 0 (of the BCCH radio) will be This interface uses LAPDm protocol for signaling, to used to carry the signalling between the BS (BSC, MSC) and the MS. These are: conduct call control, measurement reporting, Um, Radio or Air Interface

handover, power control, authentication, authorization, location update and so on.


• • • • •

BCCH: Broadcast Control Channel FCH: Frequency Correction Channel SCH: Sync Channel CCCH: Common Control Channel RACH: Random Access Channel

BSS Interfaces A interface: between MSC and TCSM - 2 Mbit/s interface Ater interface: between TCSM and BSC - 2 Mbit/s interface Abis interface: between BSC and BTS - 2 Mbit/s interface - structure depends on the connection type and signalling (64 kbit/s, 32 kbit/s or 16 kbit/s) used Air interface: between BTS and MS - TDMA frame for sending signals intended for various users on the same radio frequency in different time slots. Gb interface: between SGSN and BSC - Frame Relay Protocol on 2 Mbit/s interface - or Gb over IP 36



Implementation Scenarios A over IP Concept There are two architecture options when IP is used on the A Interface: • Transcoder function is located in the BSS (that is, the standard GSM architecture). The Transcoder is the A over IP termination point. The G.711 / RTP / IP protocol is employed. • Transcoder function is located in the Core Network (that is, the 3G network architecture). The BSC is the A over IP termination point. At the same time, the BSC hides the mobility from the Core Network.

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Exercise

39


Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

40


Radio Interface Tasks

• Modulation and demodulation

• Multiplexing

•

Interleaving

• Framing

• Multi-access

•

Handover

• Channel coding

• Timing advance

•

Ciphering

• Congestion control

• Power control

•

Puncturing

• Medium access control

• Segmentation

•

• Synchronisation

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Signal measurements

Layers The signaling protocol in GSM is structured into three general layers: •

Layer 1 is the physical layer, which uses the channel structures over the air interface. Its purpose is to handle the transmission and reception of data through the protocol's defined physical channels.

•

Layer 2 is the data link layer

•

Layer 3 is the Network layer (Radio Resources Management, Mobility Management, Connection Management)


Channel organisation in GSM/GPRS In GSM, 25 MHz spectrum has been frequency divided into 124 bands, each having a bandwidth of 200 kHz. Two principles are applied to allow multiple access in GSM: • •

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FDMA: Frequency Division Multiple Access TDMA: Time Division Multiple Access


Time Division Multiple Access (TDMA), is a method of sharing a resource (in this case a radio

Physical channel and TDMA-Frame The transmission between network elements is organised in 125 µs time frames which is subdivided in 32 time slots. Time slot number 0 is required synchronisation and alarms. Then 31 time slots are left for user data transport. .

Each time slot transmits 8 bits. If a speech call is set-up, one of the time slots can be reserved for the subscriber. The remaining time slots can be allocated to other calls. 44


Time slots and bursts In Time Division Multiple Access (TDMA) one frequency is shared by, at the most, eight users. A 2 Mbit/s PCM signal can carry 31 channels, each channel occupying 64 Kbits/s. The signals from the mobile stations must be placed into a 2 Mbit/s signal that connects the BTS and the BSC.

Each mobile station must send a burst (one TDMA timeslot) of data at a different time to all the other mobile stations in the same cell. The mobile then falls silent for the next seven timeslots and then sends the next burst and so on.

Each timeslot is referred to as a physical channel as information can be transmitted in it. It is possible to share a physical channel amongst many processes or users. These are referred to as logical channels. 45


GSM – logical channels Logical channels imply partial use of physical channels by many sources. Thus each physical channel can contain a number of logical channels. Each logical channel performs a well-specified task.


GSM – logical channels Control channels (CCH) • • •

Frequency correction channel (FCCH) Synchronising channel (SCH) Broadcast common channel (BCCH)

Common control channels (CCCH) • • •

Paging channels (PCH) Random access channel (RACH) Access grant channels (AGCH)

Dedicated Control Channels (DCCH) • • •

Standalone dedicated control channels (SDCCH) Slow associated control channels (SACCH) Fast associated control channels (FACCH)

Traffic channels (TCH) 47


Common Channels Broadcast Channels

Common control channels

Frequency Correction Channel (FCCH)

Paging Channel (PCH)

• • •

Pure sine wave. The MS searches for this channels to switch on. Downlink.

Synchronisation Channel (SCH) • •

After locking to the frequency the MS synchronises with the SCH. The SCH contains the BSIC of the BTS and the TDMA frame number (used in encryption).

Broadcast Control Channel (BCCH) Common information about the BTS: • • • • •

Used frequencies Frequency hopping sequence Channel combination Paging groups Surrounding cell information


• •

Used by BTS to page a mobile. A downlink channel only

Random Access Channel (RACH) • • •

Used by the MS to request a dedicated control channel. Used for e.g. mobile originated calls. An uplink channel only

Access Grant Channel (AGCH) • •

Used by the BTS to assign a dedicated control channel. A downlink channel only

Dedicated Channels Dedicated control channels

Traffic Channels

Stand Alone Dedicated Control Channel (SDCCH)

Full Rate (TCH/F)

• • •

Bi-directional channel. Used for call set-up procedures, e.g. authentication. The traffic channel (TCH) is assigned by using SDCCH

Slow Associated Control Channel (SACCH) • • • •

Associated with SDCCH and TCH. Measurement reports. MS power control. Timing alignment

Fast Associated Control Channel (FACCH) • • •

Associated with TCH. For quick control communication, e.g. handover. Physically replaces 20 ms of speech, “stealing mode”


• • •

Bi-directional channel. Used for speech or data transmission. User data bit rate 13 kbit/s.

Half Rate (TCH/H) • • •

Bi-directional channel. Used for speech or data transmission. User data bit rate 6-7 kbit/s.

Enhanced Full Rate (EFR) • • •

Bi-directional channel. Used for high quality speech transmission. User data bit rate 13 kbit/s.

Radio resource management (Layer 3) Available resources for GPRS GSM timeslots are used for circuit switched (CS) traffic and assigned by the GSM network, whereas timeslots for packet switched (PS) traffic are assigned by the PCU. Circuit switched traffic has priority over packet switched traffic. But when there are idle GSM timeslots, one would like to transmit as much PS traffic on it. GPRS timeslots are classified into dedicated, default and additional timeslots:

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•

Dedicate timeslots are exclusively reserved for GPRS traffic and no CS traffic can be transmitted on them.

•

Default timeslots are by default for GPRS traffic channels that can be dynamically configured to handle CS load if needed.

•

Additional timeslots by default carry CS traffic but can be dynamically configured into a GPRS timeslot when required. During peak GPRS traffic periods, additional channels are switched to GPRS use, but only if the CS traffic load permits that to occur.


Base Transceiver Station TRX The radio resources are the frequencies allocated to the Base Station. The particular hardware element inside the BTS responsible for transmitting and receiving these radio frequencies in each of the GSM channels (uplink and downlink together) is appropriately named "transceiver (TRX)". Base stations can use several TRXs, but there is at least one TRX that can carry common channels. A larger traffic volume affects the number of channel frequencies in a certain cell (TRXs).


Base Transceiver Station The type and location of the BTS depends on the characteristics of the surroundings. In city areas, cells are usually smaller than in the countryside. The rule is that the higher the frequency, the smaller the size of the cell. It means that the potential cell coverage in GSM 900 is larger than for 1800 and 1900 networks. A BTS is a physical site from where the radio transmission in both the downlink and uplink direction takes place. A Base Station site might have several TRXs. These TRXs are then configured into one, two or three cells. If a BTS is configured as one cell it is called an "omnidirectional BTS“ (transmits and receives 360 degrees) and if it is configured as either two or three cells it is called a "sectorised BTS“.

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Global Cell parameters Mobile Country Code (MCC) and Mobile Network Code (MNC) The MCC defines the code of each country globally while the MNC defines the unique network code within a country. Location Area Code (LAC) The MSC service area has been divided into several smaller areas, which are called location areas (LA). Each location area has a unique number - a location area code (LAC) - to identify the area. Paging a mobile in case of an incoming call is based on the location area. Routing Area Code (RAC) One or more cells form a Routing Area (RA), which is a subset of one Location Area (LA). The RA is unique within a Location Area. One Routing Area is served by one SGSN. Cell Identity (CI) A location area may include several BSCs, BCFs and 53 © Nokia Solutions and Networks 2015 BTSs. Therefore, a unique Cell identity (CI) is needed to define each individual cell within a location area.

Location Area and Routing Area Mobility management in the GPRS network is handled in a similar way to the existing voice service. When creating a RA the user identifies the obligatory parameters: • • • •

Mobile Country Code (MCC) Mobile Network Code (MNC) Location Area Code (LAC) Routing Area Code (RAC)

Routing area identification (RAI): RAI = MCC+MNC+LAC+RAC The RA and the BTS are linked logically together by the RAI. Routing Areas are created in the BSS Radio Network Configuration Database (BSDATA) and uses a serving PCU for the cell when the operator enables the GPRS traffic in that cell. RAI = MCC+MNC+LAC+RAC Optimal Routing Area size If the Routing Area size is too large, the paging channels and capacity will be saturated due to limited LAPD Abis or radio interface CCCH paging capacity. With a small Routing Area there will be a larger number of 54 Nokia Solutions and Networks 2015 Routing Area © updates.

Regional Organization of GPRS

55


Network Colour Code (NCC) and Base station Colour Code (BCC) Network colour code (NCC) • • •

In the vicinity of country borders it is possible for the mobile to receive the same frequency from both countries NCC is used to define which network a particular frequency belongs to and from which a mobile gets its service The range of NCC is between 0-7

Base station colour code (BCC) • • •

Within a national network, due to the limited number of carriers, frequencies need to be reused often and mobiles receive the same frequency from several sources The BCC describes a group of BTSs using a set of frequencies -another BCC is given to the neighbouring frequency set The range of BCC is between 0-7

NCC + BCC = BSIC (Base Station Identity Code) • • 56

BSIC is transmitted to mobiles on Synchronisation Channel (SCH) The mobile decodes this information, and is therefore able to lock onto the correct network and BTS (=cell) © Nokia Solutions and Networks 2015

Handovers Handover due to traffic reasons • •

When the capacity of a cell nears its maximum, mobile stations in the periphery of the cell may be handed over to neighbouring cell with lower traffic load. The MSC starts the procedure.

Handover due to signal quality and strength • • • • •

When a mobile subscriber is moving during a call, he may travel from one cell to another. Frequency resources of previous cells can not be used any more. The mobile station is handed over to the new cell. The BSC controlling the current cell makes the decision to perform a handover. There are four types of these handovers:

o o o o

57

INTRA-BSC INTRA-CELL HANDOVER (same cell) INTRA-BSC INTER-CELL HANDOVER (different cells) INTER-BSC HANDOVER INTER-MSC HANDOVER


Handover cases INTRA-BSC INTRA-CELL HANDOVER (same cell) Between two TS in the same carrier or two carriers in the same BTS INTRA-BSC INTER-CELL HANDOVER (different cells) Between two carriers in different BTS’s INTER-BSC INTER-CELL HANDOVER Between two BTS’s in different BSCs via MSC INTER-MSC HANDOVER Between two BSCs in different MSCs Inter-BSC and Inter-MSC handover are determined by the BSC but executed by the MSC (signalling and call control needed)

Inter-system handover GSM-UMTS From GSM BSS to UTRAN and from UTRAN to GSM BSS

58


Modulation GSM uses digital techniques where the speech and control information are represented by 0s and 1s. By altering the characteristic of a radio signal for every bit in the digital signal, we can "translate" an analogue signal into a bit stream in the frequency domain. This technique is called modulation. Analogue signals have three basic properties, so there are basically three types of modulation processes in common use: • • •

amplitude modulation frequency modulation phase modulation

GMSK (Gaussian Minimum Shift Keying) The GMSK modulation scheme is used for GSM and GPRS as it provides minimum spectral requirements and constant output power. In this scheme, each bit is represented by one symbol. The 8PSK modulation scheme is used for EGPRS. This modulation scheme is three times higher than of GMSK. The transmitted symbols are one of eight sinusoids, which have the same amplitude and frequency but differ in phase.

59


Radio Network Objects Base Station Controller (BSC) contains parameters specific to the base station controller. There is only one object of this type in the database. Base Control Function (BCF) contains operating and maintenance specific data of the BTS site. Base Transceiver Station (BTS) contains BTS parameters. A BTS's parameters are divided into two different groups: Common parameters (segment-specific, which are used for all BTSs in a segment) and BTS-specific parameters. A segment consists of at least one BTS or a group of BTSs that are served by one BCCH. Handover Control (HOC) contains parameters which controls the handover procedure. Power Control (POC) contains parameters which controls the power control procedure. Transceiver (TRX) contains TRX specific data Radio Timeslot (RTSL) contains parameters for the physical radio timeslot Adjacent GSM Cell (ADJC) contains adjacent-cell-specific parameters. There is an adjacent cell object for each adjacent GSM cell. Mobile Allocation Frequency List (MAL) contains a list of the frequencies that the cell uses in radio frequency (RF) hopping. Routing Area (RA) contains list of NSEIs servicing the Routing Area. RA is used for PCU selection algorithm Network Service Entity (NSE) contains information about maximum configuration and features. Dynamic Abis Pool (DAP) contains information about cell allocation in Abis interface. 60 © Nokia Solutions and Networks 2015 Packet Control Unit (PCU) contains information about PCU address and type.

Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

61


Initiating a mobile originated call The Mobile Station user dials a number. The serving MSC analyses the calling subscriber data. Depending on the subscriber data, the MSC will:

– – –

authorise or deny the use of the network activate the requested service route the call.

If the dialled number is an MSISDN of another Mobile Station belonging to the same network, an HLR enquiry is performed to obtain the MSRN.

–

The procedure is same as that of a PSTN originating call.

If the dialled number is any other number, the call is routed out to the Public Switched Telephone Network (PSTN) via the Gateway MSC.


GSM Call Flow •

The first part to mobile call is when you first turn on your phone.

•

The mobile scans the available frequencies and measures the received level on each channel.

•

You get to a nearby cell site, the cellular network checks your account.

•

•

If you have a valid telephone number and your account is good then your call proceeds.

Finally the GSM system decides which cell has to handle the mobile station which is usually the cell site delivering the highest signal strength to the mobile.

•

To establish a connection, a frequency is needed to transmit on.

•

Then the mobile synchronizes with the cell site (SCH).

•

So the mobile tries to find out broadcast channels.

•

A base station’s Broadcast Control Channel continuously sends out identifying information about its cell site.

•

For the initial period mobile acts as a receiver checking for a signal from any base station with in the range.


Mobile Originated Call (MOC) 1. The MS uses RACH to ask for a signaling channel. 2. The BSC allocates signaling channel using AGCH. 3. When the channel is allocated, it send its IMSI and VLR is signed as busy. 4. The MS sends a call set-up request via SDCCH to the MSC/VLR. Over SDCCH all signaling preceding a call takes place. This includes: •

Marking the MS as “active” in the VLR

•

The authentication procedure

•

Start ciphering

•

Equipment identification

•

Checking the called party’s number to the network

5. The MSC/VLR instructs the BSC to allocate an idle TCH. The BTS and the MS are told to tune to the TCH. 6. The MSC/VLR forwards the called party number to an exchange in the PSTN, which establishes a connection to the subscriber. 7. If the called subscriber answers, the connection is established. 64 © Nokia Solutions and Networks 2015

Call Handling in MSC •

A subscriber switches on his phone in an area where a local operator provides network service.

•

The area is connected through an air interface to the VLR, which is integrated into the MSC.

•

The home operator of the subscriber also needs to know the location of the subscriber. Therefore it maintains another register – the HLR.

•

The HLR stores the basic data of the subscriber on a permanent basis. The only variable information in the HLR is the current location of the subscriber (the VLR address).

•

The VLR address is needed, because the HLR needs to know from what MSC/VLR to ask for routing information in case of a mobile terminated call (a call to the mobile station).

•

When the subscriber moves to another VLR area, its data is erased from the old VLR and stored in the new VLR.

•

The transaction that enables the network to keep track of the subscriber isNetworks called2015 a location update. © Nokia Solutions and

65

Each MSC/VLR typically contains many location areas. We can define a LA as an area in which we search for the subscriber in case there is a call for him. Each LA is identified by a Location Area Identity (LAI), and it has the following structure:

Paging is a signal that is transmitted by all the cells in the LA. It contains the identification of the subscriber. The identification is called TMSI and is a unique identity temporarily allocated to visiting mobile subscribers by the visitor location register. Even if the paging signal is received by several mobile stations in the LA, only one of them thus recognises the identification and answers to it. As a consequence of this answer, a point to point connection is established. Now the two subscribers are connected, and traffic can be carried through the network. Location Area Paging

Paging

BTS

Now that we know the LA of the subscriber, we can start searching for him. To locate the subscriber, a paging process is initiated in the location area.


Mobile responds to paging

BTS Paging

BTS

Types of location updates Power On Also known as “IMSI Attach” and “Location Registration” Done every time a Mobile Station is switched on. Generic Done every time a Mobile Station changes a location area. Periodic Is a feature which forces MS’s to send a registration message to the network at predefined intervals. If an MS miss a registration, the network will mark the MS as detached and ensures that needless paging is not performed. 67 © Nokia Solutions and Networks 2015

Number of channels required during call set-up (1) •

Channel to transmit information to help the mobile station to tune into the network.

•

Channel to transmit synchronisation information.

•

Channel to transmit information about the network to help the mobile know about the frequencies being used in its cell as well as in surrounding cells.

68



Channel to transmit mobile station’s request to initiate call set-up.

•

Channel to set up a call.

•

Channel to transmit handover information.

69



Channel to page the called party.

•

Channel to transmit measurements. Conclusion: No channel left for conversation! Solution: We must send more than one type of information on a channel by sharing it.

70


Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

71


BSC controls GSM/EDGE radio network (BSS/GERAN): • • • • • •

Radio resource management Circuit switched call control Packet switched services control Radio network configuration and recovery BTS and BSC O&M Circuit and packet switched user plane transport

Complete Nokia BSC is basically composed with: • • • • • • • •

GSWB = Group Switch (Bit) 1 Cabinet in which there are 7 BCSU - Base Station Controller Signalling Unit (6 working BCSU and one BCSU in spare state) 2 MCMU - Marker and Cellular Management Unit (1 working MCMU and 1 spare MCMU) 2 CLS - Clock and Synchronisation Unit (1 working CLS and 1 spare CLS) 1 OMU - Operation and Maintenance Unit ET = Exchange Terminal Message Bus (MBIF) power units


BSC Architecture

73



MCMU – Marker and Cellular Management Unit • • • •

controls and supervises the Bit Group Switch responsible for cells and radio channels that are controlled by the BSC reserves and keeps track of the radio resources requested by the MSC and the handover procedures of the BSC manages the configuration of the cellular network

BCSU – BSC Signaling Unit • •

Traffic volume It consists of two parts, which correspond to the A and Abis interfaces: • •

The A interface: performing all message handling and processing functions of the signaling channels connected to it. The Abis interface: controls the air interface channels associated with transceivers (TRXs) and Abis signaling channels; every speech circuit on the Abis interface is mapped one-to-one to a GSM-specific speech/data channel on the air interface.

OMU – Operating and Maintenance Unit • traffic measurement functions • maintenance functions • system configuration administration functions 75 © Nokia Solutions and Networks 2015 • System management functions • LANinformation topologyclassification management

GSW – Group Switch • •

conveys the traffic passing through the BSC as well as switching the tones to the subscribers of the exchange and to the trunk circuits establishes the needed connections to the signaling units, the internal data transmission channels and the submultiplexers (SMUX) of the BSC

CLS (CLOC) - Clock and synchronization unit • • •

The CLS generates the clock signals necessary for the BSC. The oscillator of the CLS is normally synchronized to an external source, usually an MSC, through a PCM line. Up to three additional PCM inputs are provided for redundancy.

ET – Exchange Terminal units • •

• •

PCM trunk circuit interface connected to the Group Switch (GSW) and via this to the computer unit supervising the Exchange Terminal, to the Clock Equipment (CLS), to the Hardware Alarm Collection Unit (HWAL) and to the power supply Input transmission direction) Output transmission direction


mcBSC – Multicontroller BSC Multicontroller Platform combines a compact and scalable hardware platform with modular and flexible radio network controller software to create a network controller implementation with unrivalled modularity and space efficiency. Full IP based Multicontroller Platform enables native support for BSC packet transport on all interfaces and can be configured to serve high voice and data traffic volumes and manage high number of cells. Multicontroller BSC provides capacity for 4400 TRXs. When the need comes to adopt a new technology, Multicontroller BSC can be converted into a 3G Multicontroller RNC. With full IP-based Multicontroller BSC, all the interfacing are based on IP over Ethernet transmission - Packet Abis/Ethernet, AoIP, Packet Ater and Gb/IP. When Multicontroller BSC is combined with Flexi BSC also TDM (time division multiplex) based interface options are available for the legacy radio network served by the Flexi BSC part in the combined Flexi BSC - Multicontroller BSC installation. 77 © Nokia Solutions and Networks 2015

Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

78


Flexi Multiradio BTS Flexi Multiradio BTS is a base transceiver station that is part of the Nokia Flexi BTS platform for GSM/EDGE, WCDMA and LTE networks.

The key benefits of the Flexi MR BTS are: • • • • • •

wide area coverage a highly modular structure to allow maximum flexibility for constructing a wide range of different configurations. high power and efficient power amplifiers future-proof design cost-efficient site implementations a lightweight solution.


Flexi Multiradio BTS Modularity Modularity was one of the key design goals of the Flexi MR BTS. Various BTS solutions can be constructed using the following modules and devices: • • • • • • •

80

One system module that includes a transmission submodule One optional baseband extension module (basically a system module without the transmission submodule) One or two optional power supply modules One to three RF modules or optional remote radio heads (RRHs), or with RF chaining up to 12 RF modules or remote radio heads An optional multiradio combiner An optional GPS mediator Optional antenna line devices such as mast head amplifiers (MHAs), tower mounted amplifiers (TMAs), and remote electrical tilt (RET) equipment.


Flexi Multiradio BTS Installation Options The possible implementations include: • • •

81

outdoor installations (top of the mast, base of the mast or roof of a building indoor implementations (floor rack installations, spacelimited site installations and other indoor installations) distributed BTS sites (minisites, feederless sites)


Flexi Multiradio BTS Dimensions The basic Flexi MR BTS modules (system module, RF module, baseband extension module, and power supply module) have the same physical dimensions. Mechanically, the basic Flexi MR BTS modules consist of a core, a casing, fans and cables. Description: • • • •

82

Width = 448 millimetres (standard 19 inch rack) Height = 133 millimetres (3U) depth = 400 millimetres without the front cover and 574 millimetres with the front cover installed. average weight of a module is approximately 20 kg.


Flexi Multiradio BTS Modules of the BTS The minimum configuration of the Flexi MR BTS includes one system module and one RF module. The interface between the system module and RF module is optical and allows the implementation of a distributed BTS site where the physical location of the system module is not the same as the location of the RF module. The system module can be located indoors in a cellar, for example, and the RF module on the roof close to the antenna. The remote radio head, in particular, enables easy mast, pole or wall installation. It is possible to expand the BTS by adding one optional baseband extension module to the system witch can more than double the baseband processing capacity. 83


Flexi Multiradio BTS Modules of the BTS The tasks of the system module are: Teste • • • • • • • • •

control plane processing centralised timing user-plane processing multiplexing Summing Ethernet switching transport processing providing external interfaces power distribution.

The basic tasks of the RF module are: Teste • • • • •

84

signal modulation Channelising analogue RF processing power amplifications signal filtering at the antenna interfaces.


Flexi Multiradio BTS Power supply The BTS can be further expanded by adding an optional power supply module. This module provides AC to DC conversion if direct current is not available at the site. It is also possible to equip the power supply module with up to three backup batteries to ensure BTS operation during short power breaks.

85


Flexi Multiradio BTS System Module – GSM The Flexi Multiradio System Module provides the GSM/EDGE functionality to the BTS. It provides internal and external BTS connections, and stores and runs the GSM/EDGE BTS software. The System Module also receives and stores the unit identification information of all other units of the BTS. ESMB and ESMC System Modules support configurations of up to 18 and 36 TRXs respectively. The main functions of the ESMB/C are: • • • • • •

GSM/EDGE BTS Operation and Maintenance Abis interfacing Open Base Station Architecture Initiative (OBSAI) connectivity Power distribution to other modules GSM/EDGE baseband BTS synchronization

External and internal interfaces in ESMB/C are: • • • • •

- Q1 - Flexi Power Alarms (FPA)

• 86


48V DC distribution, 4 outputs and 1 Auxiliary output Abis interface External Alarm and Control Interface 4 optical interfaces (OBSAI RP3-1) Auxiliary equipment interfaces Local Management Port (LMP)

Flexi Multiradio BTS Transmission submodules GSM The transmission sub-module is a separate sales item, since the sub-module type may vary according to the needs of the particular system. The sub-module is installed at the BTS site, where it is integrated as part of the system module. The transmission submodule provides the A interface towards the BSC. In provided transmission slot one- The of the • the E1/T1 transmission sub-module (FIPA) FIPAfollowing offers eighttransmission sub-modules can be used: • •

•

•

87

balanced E1/T1-interfaces. E1 transmission sub-module (FIEA) - The FIEA offers eight unbalanced E1-interfaces. Flexbus transmission sub-module (FIFA) - The FIFA offers two Flexbus interfaces connecting radio links that belong to the Flexi Hopper family. FIFA can also be used for connecting other transmission devices supporting Flexbus interface. Abis over IP Ethernet and E1/T1 (FIQx) - The FIQx transmission sub-module offers two Fast Ethernet, one Gigabit Ethernet and, four balanced E1/T1 interfaces. The optical transceiver module is required for Gigabit Ethernet. Abis over IP Ethernet and E1 (FIYx) - The FIYx transmission submodule offers two Fast Ethernet, one Gigabit Ethernet and, four unbalanced E1 interfaces. The optical transceiver module is required for Gigabit Ethernet. © Nokia Solutions and Networks 2015

Flexi Multiradio BTS RF Module (FXxx) The RF module can include one, two or three transceivers or “pipes”. One transmitter and receiver (one branch) can create one sector, designed to concurrently transmit and receive multicarrier signals of multiple radio technologies. It contains two receive chains to provide the functionality of 2-way receive diversity functionality. It is possible to chain up to 3 radio modules. External and internal interfaces in FXxx are: • • • • • • • 88

48V DC input External Alarm interface compatible with FPA 3 optical interfaces (OBSAI RP3-1) 6 Antenna interfaces - 3 duplexed and 3 RX diversity FXDA/B, FXEA/B, FXDJ have 3 RX diversity outputs and FXCx/FXFx has 6 Rx outputs Integrated DC line OVP, Class II rated to 5kA pulse (FXFB, 90 W RF Module variants) Remote Electrical Tilt (RET) support (FXFB, 90 W RF Module variants) © Nokia Solutions and Networks 2015

Flexi Multiradio BTS RRH – Remote Radio Head The remote radio head (RRH) is a fully operational RF module that is easy to install on a mast, pole, or wall.. It can be installed up to 200 meters away from the other modules of the Flexi MR BTS or up to 15 kilometers. The dual-transmit (2TX) remote radio head is available for two frequency bands and offers 2 x 40 W output power using two multicarrier power amplifiers (MCPA) that can handle up to two carriers each. The key benefits of the remote radio head are: • • • •

89

High output power combined with small dimensions and low power consumption Prepared for HSPA Evolution and LTE applications. It can be provided DC or AC power locally Supports RRH chaining, where 1 SM can handle up to 3 chains that contain up to 4 remote radio heads per chain with a total maximum of 12 remote radio heads. © Nokia Solutions and Networks 2015

Other equipments RET (Remote Electrical Tilt) Amplifier)

90


MHA (Master Head

Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

91


Legacy Abis Interface

92


•

The Abis is the interface between the BSC and the BTS.

•

It is a 2 Mbit/s interface.

•

The capacity of the Abis interface depends on the type of Signalling (16kbit/s, 32kbit/s, 64kbit/s) used between the BSC and the BTS.

•

The allocation of the channels within the Abis interface is free (TCH must occupy two successive timeslots).

•

For EDGE configuration it’s possible to define dynamically Abis pools (DAP) in 64 kbit/s steps.

Abis Interface Each BTS has one O&M channel, OMUSIG (or BCFSIG): •

it is an LAPD link connected to the BCF unit in the BTS

•

the bit rate is 16, 32 or 64 kbit/s

One TRX can handle 8 x 16 kbit/s traffic channels (TCHs): • •

93

it needs 2 PCM timeslots for TCHs in Abis 1 TRX has 1 LAPD link, TRXSIG with 16, 32 or 64 kbit/s bitrate


BSC User Interface - MMI • • •

Text based user interface Available locally in OMU, or remotely via Telnet/SSH MMI = Man Machine Interface System consisting of software. It is used by the operator to perform operation and maintenance functions in the exchange system.

•

MML = Man Machine Language A command language with which the operator can manage the operation of the exchange.

•

DIALOG / MML SESSION Sessions are either local sessions or remote sessions. Communication between the system and the user using MML command language.

94


Command Structure There are hundreds of commands, so to make it easier to work with them, they are categorized into command groups. The command groups are further grouped into command classes. The command hierarchy is like a tree with branches. On the main level there is the list of command classes. Each command class is a list of command groups. Finally, the command groups are lists of commands. A command consists of command letters and parameters. Parameters can be grouped into parameters blocks. Parameters blocks are separated with colons and parameters belonging to the same parameter block are separated with commas. A command is terminated with a semi-colon. A return after a semicolon executes the command.


The command Z, followed by a question mark, gives you the list of the command classes. To see the command groups within a command class, you would type the letter indicating the command class. For example, Z A, followed by a question mark, gives you the list of command groups within the Alarm System Administration command class. 96


Radio Network Elements BCF Base Control Function, ZEF... BTS Base Transceiver Station, ZEQ... FHS Frequency Hopping System TRX Transceiver, ZER... TSL Radio Time Slots BTS SW BTS Software Package, ZEW... HOC Handover Control Parameters, ZEH... POC Power Control Parameters, ZEU... Adj. Cell Adjacent Cells Parameter, ZEA... UMTS Adj. Cell WBTS Adjacent Cells Parameter, ZEA...

97


98


BTS 2

BTS 1 BSC

ZEE...

HW Database

TRX TRX 1 1 TRX TRX 2 2

TRXSIG / BCFSIG

TRX TRX 5 5 TRX TRX 6 6

ZDTI ZDSB

ZEV...

BTS SW

ZEW...

BCF 1ZEF...

BTS Power Control

ZEU...

BTS 3 ZEQ...

TRX TRX 3 3 ZER... TRX TRX 4 4

BTS ZEA... -Adjacencies BTS -Handover Control

ZEH... 99


BCF, BTS, TRX Handling

Usefull commands

ZEF_  BCF ZEQ_  BTS

Units states and alarms

ZER_  TRX

ZUSI;

ZE_S  Change BCF, BTS, TRX state

To display units state

ZAHO; Active alarms in BSC ZEOL; Active BTS alarms

For A Interface:

ZAHP; BSC alarm history

ZNET;

ZEOH; BTS alarms history

ZNHI:; Display BSSAP status

Display A interface information (SL, routes)

ZNRI:; Display route status Physical layer (PCM monitoring) ZAHO:ET,; PCM alarms

For Gb interface and GPRS/EDGE:

ZYEF:ET,>; PCM state

ZFUI;

ZYMO:ET,; PCM statistics

ZFXO:; NSVCI information ZQRI;

For Abis interface:

IP configuration

ZEQO::GPRS; Check GPRS at BTS level

ZDTI:::; DChannel states

Display

ZEEI:; Display the Radio network (BCF, BTS, TRX) ZERO:, configuration

Bearer channel information

Display EDGE dynamic pool

10 © Nokia Solutions and Networks 2015 0

ZESI:; Display EDGE dynamic pool configuration check and Fallback ZEWO:;

Check BCF SW

ZWQO:CR;

Check the BSC SW version

ET Interface If necessary, change the working state (ZUSC) to WO-EX.

If the ET is already connected, it has a controlling BCSU (Base Station Controller Signaling Unit) and process info. The controlling process can be •

SC7PRB: A interface

•

ABIPRB: Abis interface

•

ERATES: Gb interface

EQMANA means the ET is not connected.

10 1


GPRS cell specific parameter First the operator has to activate the GPRS feature in the BSC with the cell- specific parameter GPRS enable (GENA) and define which TRXs are capable of GPRS with the parameter GPRS enabled TRX (GTRX) . To activate the EGPRS feature, the operator uses the BTS-specific parameter EGPRS enable (EGENA) . The BTS can contain both EDGE-capable and nonEDGE-capable TRXs (HW), if GPRS is disabled in the non-EDGE-capable TRXs. The operator needs to define which TRXs are capable of EGPRS with the parameter GPRS enabled TRX (GTRX) . The BSC can upgrade or downgrade the number of radio resources allocated for GPRS use according to the varying needs of the circuit switched and GPRS traffic.

10 2


10 3


ZEEI - OUTPUT RADIO NETWORK CONFIGURATION You can list the whole BSC (ZEEI;) or list the configuration by specifying BTS#, SEG#, BCF#, BTS Name etc. What you can get its CI, LAC, Type of site (Multiradio, Edge, Ultrasite), Working state (Working, Locked), Allocated frequencies (BCCH), Hopping type (RF, BB), Occupied FR, HR timeslots and GPRS timeslots (gives the current territory size, not necessary occupied).

ARFCN BCF

ET

BCF Type

Control channels

LAC Cell Id

BCSU

BTS Name BTS id

OMUSIG name and state

TRX Id

Calls

States

10 4


Example

10 5


10 6


10 7


TRX - Channels

10 8


Example Creating site Steps to create the site: •

DAP

•

BTS Parameters

•

OMUSIG

•

HOC and POC

•

LAPD

•

TRX

•

BCF

•

•

BTS

Neighbours (Incoming and Outgoing 2G, Outgoing 3G).

•

MAL LIST

•

GPRS (GENA and EGENA)

•

Attach MAL LIST to BTS

•

EXTERNAL ALARMS

•

Unlock Site

Once this steps are finished, confirm the site’s features and if its unlocked using: ZEEI:BCF=;

10 9


Example Pre-checks Pre-check the site and realise if the some of the features are already created: ZEEI:BCF=; ----------- Check BCF. Should appear: /* BCF NOT FOUND */ ZEEI:BTS=&; --Check BTS. Should appear: /* BTS NOT FOUND */ ZWUP:ET, ZUSI:ET,; ---------------- Check if ET is WO. If not (SE-NH): ZUSC:ET,:SE; ZUSC:ET,:TE; ZUSC:ET,:WO; ZESI:ID=; ------------- Check DAP. There should be no information, DAP not yet existing ZEEI::BCSU; ----------------- Gives BCSU information to distribute among BCF and LAPD ZFXI:NSEI=; --------- Gives PSEI to create DAP

11 0


Commands #DAP ZESE:ID=,CRCT=-<1ºtimeslot>,SIZE=,PSEI=< ZFXI:NSEI=xxx>; ZESE:ID=356,CRCT=1874-18,SIZE=9,PSEI=12; #OMU ZDSE:OMxx:BCSU,< ZEEI::BCSU; O&M >:62< O&M,"62 ... OPERATION AND MAINTENANCE PROCEDURES“>,1:32(or 1:64 = subtimeslots),-,; ZDSE:OM346:BCSU,3:62,1:32,1874-31,0; # LAPD ZDSE::BCSU,(ZEEI::BCSU; D-CHANNEL TELECOM LINKS):0 (" 0 ... SIGNALLING PROCEDURES, DEFAULT VALUE"),:32 OU 64 (subtimeslots),0, 2 or 4 (subtimeslots); ZDSE:T3461:BCSU,1:0,1:64,1874-27; ZDSE:T3462:BCSU,2:0,2:32,1874-28,0;

11 1


Elements #BCF ZEFC:xxx,E or M(E=EDGE,=MULTIRADIO):DNAME=(OMUSIG); ZEFC:356,E:DNAME=OM356; #BTS ZEQC:BCF=xxx,BTS=xxx,NAME=(BTSname),SEGNAME=(SEGname):CI=xxx,BAND=800:NCC= x,BCC=x,MCC=xx,LAC=xxxx:HOP=RF or N (RADIO FREQUENCY or none),HSN1=xx,HSN2=xx:RAC=xx; ZEQC:BCF=346,BTS=346,NAME=GU20831,SEGNAME=ALBODECIMAX:CI=20831,BAND=800:NCC=0,BCC= 2:MCC=740,MNC=1,LAC=10278:HOP=RF,HSN1=57,HSN2=57:RAC=0; #MAL List ZEBE:MAL,xx,:FREQ=< FREQ1 >& &< FREQ3>; ZEBE:MAL,3,800:FREQ=130&154&232; Attach to MAL list to BTS ZEQA:BTS=346:MAL=3,MO=0,MS=1;

11 2


#HOC and POC ZEHC:SEG=346; ZEUC:SEG=346;

#TRXS ZERC:BTS=xxx,TRX=xx:PREF=P or N (TRX PREFERENCIAL or not),GTRX=Y or N;DAP=xx:TSC=,FREQ=PCMTSL=:DNAME=:CH0xxxx=,CH1=xxxx…CH7=xxxx; ZERC:BTS=346,TRX=1:PREF=P,GTRX=Y,DAP=346:TSC=1,FREQ=136,PCMTSL=18741:DNAME=T3461:CH0=MBCCH,CH1=SDCCB,CH2=CCCHE,CH3=SDCCH,CH4=TCHD,CH5=TCHD,CH6=TCHD,CH7=TC HD; ZERC:BTS=346,TRX=2:PREF=N,GTRX=Y,DAP=346:TSC=1,FREQ=130,PCMTSL=18743:DNAME=T3462:CH0=TCHD,CH1=TCHD,CH2=TCHD,CH3=TCHD,CH4=TCHD,CH5=TCHD,CH6=TCHD,CH7=TCHD;

#UNLOCK ZDTC:OM476:WO; ZDTC:T3461:WO; ZERS:BTS=346,TRX=1&&4:U; ZEQS:BTS=346:U;

#GPRS AND EDGE 11 © Nokia Solutions and Networks 2015 ZEQV:BTS=376:CDEF=16,CDED=8,EGENA=Y; 3

Exercise Creating a Site on Labs’ Flexi BSC

# LAPD ZDSE::BCSU,(ZEEI::BCSU; D-CHANNEL TELECOM LINKS):0 (" 0 ... SIGNALLING PROCEDURES, DEFAULT VALUE"),:32 OU 64 (subtimeslots),0, 2 or 4 (subtimeslots); #OMU ZDSE:OMxx:BCSU,< ZEEI::BCSU; O&M >:62< O&M,"62 ... OPERATION AND MAINTENANCE PROCEDURES“>,1:32(or 1:64 = subtimeslots),,; #BCF ZEFC:xxx,M(MULTIRADIO):DNAME=(OMUSIG); #BTS ZEQC:BCF=xxx,BTS=xxx:CI=xxx,BAND=800:NCC= xx,BCC=xx,MCC=xx,LAC=xxxx:HOP=RF or N (RADIO FREQUENCY or none):RAC=xx; #TRXS ZERC:BTS=xxx,TRX=xx:PREF=P or N (TRX PREFERENCIAL or not),GTRX=Y or N:TSC=,FREQ=PCMTSL=11 © Nokia Solutions and Networks 2015 :DNAME=:CH0xxxx=,CH1=xxxx…CH7=xxxx; 4

Commands #LAPD ZDSE:T0001:BCSU,0:0,1:32,373-20,0; ZDSE:T0002:BCSU,1:0,1:32,373-20,4; #OMUSIG ZDSE:OM002:BCSU,1:62,1:64,373-31; #BCF ZEFC:2,M:DNAME=OM002; #BTS ZEQC:BCF=2,BTS=2:CI=40060,BAND=800:NCC=7,BCC=3:MCC=268,MNC=06,LAC=00101:HOP=N:RAC= 031; #TRX ZERC:BTS=2,TRX=1:PREF=P,GTRX=N:TSC=3,FREQ=235,PCMTSL=3731:DNAME=T0001:CH0=MBCCH,CH1=SDCCH,CH2=TCHD,CH3=TCHD,CH4=TCHD,CH5=TCHD,CH6=TCHD,C H7=TCHD; ZERC:BTS=2,TRX=2:PREF=N,GTRX=N:TSC=3,FREQ=132,PCMTSL=37311 © Nokia Solutions and Networks 2015 3:DNAME=T0002:CH0=TCHD,CH1=TCHD,CH2=TCHD,CH3=TCHD,CH4=TCHD,CH5=TCHD,CH6=TCHD,CH7 5 =TCHD;

Introduction


BSS Overview


BSS Radio Network

Abis and MML


Commissioning

11 6


Commissioning Preparing for Commissioning Before commissioning, the physical installation of the BTS (modules, cabling, antennas and radios) must be completed. Make sure a PC with 2G Flexi BTS Site Manager installed. Parameter values must be available to be entered during commissioning. The parameter values are provided by the network planning process. BSC settings: the BTS site must already be created at the BSC for commissioning to be successfully completed. Transmission network setup: the transmission link(s) between the BSC and the BTS must already be set up so that there is a transmission path from the BSC to the BTS for all the Abis channels.


Software needed in order to do commissioning/ supervising the Flexi Mutiradio is 2G Flexi BTS Site Manager (mandatory). Software can be downloaded via NOLS. Please ensure that both manager software must be compatible with the software level installed in the BTS. User can check the compatibility at Software compatibility of Flexi Multiradio BTS document in NED or Information Browser.

2G Flexi BTS Manager Nokia Siemens Networks 2G Flexi BTS Site Manager allows the BTS operators to: Commission Configure Monitor the BTS These tasks are performed with option: at the BTS site (known as Local Connection) via communication from the OSS system. BSC site (known as Remote Connection). 2G Flexi BTS Site Manager is for maintaining and commissioning Flexi Multiradio base transceiver stations.


2G Flexi BTS Manager To launch the 2G Flexi BTS Manager user can click shortcuts in the Start Menu, and following window will come up.


2G Flexi BTS Manager


Flexi 2G BTS Site Manager window The main functions of Flexi BTS manager are: • BTS commissioning • BTS supervision • BTS maintenance • BTS testing In main menu, the view are: • Alarms • Base Station • Commissioning • Supervision • Transmission • Tests

12


1

Commissioning Wizard


2G Flexi BTS Manager Commissioning The Commissioning Wizard will guide user through configuration. By clicking "next" button the wizard will continue to the next configuration screen. The wizard consist following screen: •

Site specific Information

•

Hardware Configuration

•

Transmission Parameter


Hardware Configuration Module Configuration

configure various radio modules, synchronization master, and radio masters


Hardware Configuration Local Sector setting

configure and associate antennas of only one type of RF unit (RM) to a particular local sector and specify per TRX power


Hardware Configuration Antenna Settings

Select the antenna line settings, specify MHA settings, provide information for feeder voltage, feeder loss, VSWR minor and major limits for the selected antenna


Hardware Configuration RET settings

configuration of RETs in either online or offline mode


Transmission Parameter Physical settings Setting the functionality of interface (E1 or T1)


Transmission Parameter Abis Termination • In Satellite Abis, specify if

there is a satellite circuit in the link between the BTS and the BSC • Enable Abis Signal Mapping allows the BSC to dynamically provide the Abis allocations (TRXSIG, TCH, EDAP) for a BTS • If Allow Abis Allocations from BTS Manager is ticked (enabled), user can allocate the Abis allocations from the BTS Manager but these allocations can be overridden by the BSC 12 © Nokia Solutions and Networks 2015 9

Transmission Parameter Abis Allocation • Enter the Abis Allocation parameters (OMUSIG, TRXSIG, TCH and EDAP) • If Enable Abis Signal Mapping is chosen, only OMUSIG can be specified, the rest will be mapping by the BSC • If Enable Abis Signal Mapping is chosen and Allow Abis Allocations from BTS Manager is ticked , all signaling can be allocated in Abis, but these allocations can be overridden by the BSC 13 © Nokia Solutions and Networks 2015 0

SCF preview Summary • From this summary, user can check whether the commissioning step has been completed. • This can be checked by looking at the indication color of each step, green means ok, red means not complete


Commissioning completed


After commissioning


13 4


Nsn 2g Gsm Basics

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