Multiple RRUs in One Cell

Multiple RRUs in One Cell RAN12.0

Feature Parameter Description

Issue

03

Date

2010-12-20

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2011. All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without prior written consent of Huawei Technologies Co., Ltd.

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WCDMA RAN Multiple RRUs in One Cell

Contents

Contents 1 Introduction ................................................................................................................................1-1 1.1 Scope ............................................................................................................................................ 1-1 1.2 Intended Audience ........................................................................................................................ 1-1 1.3 Change History.............................................................................................................................. 1-1

2 Technical Description ..............................................................................................................2-1 2.1 Overview of Multiple RRUs in One Cell ........................................................................................ 2-1 2.2 Distributed Sector Configuration ................................................................................................... 2-1 2.3 0.5/0.5 Configuration ..................................................................................................................... 2-2

3 Engineering Guidelines...........................................................................................................3-1 3.1 Distributed Sector Configuration ................................................................................................... 3-1 3.2 0.5/0.5 Configuration ..................................................................................................................... 3-1

4 Parameters .................................................................................................................................4-1 5 Counters ......................................................................................................................................5-1 6 Glossary ......................................................................................................................................6-1 7 Reference Documents .............................................................................................................7-1

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Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd

ii


1 Introduction

1 Introduction 1.1 Scope This document describes the Multiple RRUs in One Cell feature. It also describes the engineering guidelines of this feature.

1.2 Intended Audience This document is intended for: 

Personnel who are familiar with WCDMA basics



Personnel who need to understand Multiple RRUs in One Cell



Personnel who work with Huawei products

1.3 Change History This section provides information on the changes in different document versions. There are two types of changes, which are defined as follows: 

Feature change: refers to the change in the Multiple RRUs in One Cell feature.



Editorial change: refers to the change in wording or the addition of the information that was not described in the earlier version.

Document Issues The document issues are as follows: 

03 (2010-12-20)



02 (2010-06-20)



01 (2010-03-30)



Draft (2009-12-05)

03 (2010-12-20) This is the document for the third commercial release of RAN12.0. Compared with issue 02 (2010-06-20) of RAN12.0, this issue optimizes the description and the document is renamed from Cell Digital Combination and Split to Multiple RRUs in One Cell.

02 (2010-06-20) This is the document for the second commercial release of RAN12.0. Compared with issue 01 (2010-03-30) of RAN12.0, this issue adds the information about RRU double-antenna receive mode in distributed sector configuration mode.

01 (2010-03-30) This is the document for the first commercial release of RAN12.0. Compared with issue Draft (2009-12-05) of RAN12.0, this issue optimizes the description.

Draft (2009-12-05) This is the draft of the document for RAN12.0.

03 (2010-12-20)


1-1


1 Introduction

This is a new document.

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2 Technical Description

2 Technical Description 2.1 Overview of Multiple RRUs in One Cell With the multiple RRUs in one cell feature, multiple RRUs can be used to cover different areas in one cell. In this case, the areas covered by one cell will be more flexible. The Multiple RRUs in One Cell feature is adopted by distributed base stations. It is mainly applicable to coverage scenarios such as indoor space, high-speed railways, and expressways. The multiple RRUs in one cell feature is implemented by the following two modes. 

Distributed sector configuration mode (WRFD-010205 Cell Digital Combination and Split): It is mainly applicable to coverage scenarios such as indoor spots. In this mode, a maximum of 16 RRUs can coexist in one cell to cover different areas.



0.5/0.5 configuration mode: It is mainly applicable to coverage scenarios such as high-speed railways and expressways. In this mode, a maximum of two RRUs can coexist in one cell to cover different areas.

The following sections will describe the detailed information about the two configuration modes.

2.2 Distributed Sector Configuration This section describes the feature WRFD-010205 Cell Digital Combination and Split. The distributed sector configuration mode is mainly applicable to coverage scenarios such as indoor spots. In this configuration mode, a maximum of 16 RRUs can coexist in one cell. The distributed sector configuration mode adopts digital combination and split to process the uplink and downlink signals. Figure 2-1 shows the process of the uplink digital combination and downlink digital split. In uplink digital combination, the uplink signal from the transport channel of the current RRU and the uplink signal from the lower-level RRU are combined for transmission to the upper-level RRU or BBU. In downlink digital split, the downlink signals from the upper-level RRU or BBU are sent to the transport channel of the current RRU and the lower-level RRU simultaneously. Figure 2-1 The process of the uplink digital combination and downlink digital split

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In distributed sector configuration mode, each RRU can be configured in single-antenna or double-antenna receive mode. Note that in the same sector, the antenna magnitude of all the RRU must be the same. In distributed sector configuration mode, the digital combination of uplink signals increases the background noises. If n RRUs coexist in one cell, then the increase of background noises equals 10 x lg(n). In an indoor environment, the health standards for electromagnetic radiation should be taken into consideration. Generally, the transmit power of an antenna is below 15 dBm, and the maximum transient transmit power of a UE is above 21 dBm. Indoor coverage mainly focuses on capacity. It takes into consideration limited downlink power rather than limited uplink coverage. In addition, it does not have high requirements for uplink sensitivity. Therefore, the increase of background noises caused by digital combination does not affect system performance.

2.3 0.5/0.5 Configuration The 0.5/0.5 configuration mode is mainly applicable to coverage scenarios such as high-speed railways and expressways. In this configuration mode, a maximum of two RRUs can coexist in one cell. In the downlink, two RRUs transmit the same data; in the uplink, signals from two RRUs are considered as signals from multiple antennas in one cell during demodulation, and therefore noise superimpose is not caused. Figure 2-2 shows the 0.5/0.5 configuration. Figure 2-2 The 0.5/0.5 configuration

In 0.5/0.5 configuration mode, a maximum of two RRUs can coexist in one cell and each RRU can be configured in single-antenna or double-antenna receive mode. If the RRU receives signals in single-antenna mode, the two-channel demodulation is applied to the cell. If the RRU receives signals in double-antenna mode, the four-channel demodulation is applied to the cell. Compared with two-channel demodulation, four-channel demodulation consumes twice the amount of baseband resources. The 0.5/0.5 configuration mode solves the problem that the handover between two cells in one NodeB fails because the handover area is excessively small. In addition, this mode meets the requirements of high-speed handover in the coverage scenarios such as high-speed railways and expressways. In the case of traditional configuration, the handover between two cells in one NodeB for the UE in high-speed motion fails easily because of fast signal attenuation and small handover area. In the case of 0.5/0.5 configuration, two RRUs are located in the same cell but cover different areas. In this case, there is no handover process for the UE in high-speed motion. Figure 2-3 shows the comparison between traditional configuration and 0.5/0.5 configuration.

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Figure 2-3 Comparison between traditional configuration and 0.5/0.5 configuration

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3 Engineering Guidelines

3 Engineering Guidelines 3.1 Distributed Sector Configuration This section describes the engineering guideline about the feature WRFD-010205 Cell Digital Combination and Split. In distributed sector configuration mode, one CPRI port supports a maximum of eight cascaded RRUs. A maximum of eight RRUs coexist in one cell and a maximum of three distributed cells are supported. The BBU enables digital combination of uplink signals from a maximum of two CPRI ports. A maximum of 16 RRUs can coexist in one cell. Due to the delay, the length of the interconnection optical cables between the RRUs that are located in the same cell and have neighboring coverage areas should be less than four kilometers. In the case of the DBS3900 and iDBS3900, when the WBBPa board is configured, each RRU supports only the one-antenna receive mode; when other baseband boards are configured, each RRU can support the one-antenna or two-antenna receive mode. In distributed sector configuration mode, the digital combination of uplink signals increases the background noises. When configuring the background noise of the cell, the increase of background noise caused by digital combination needs to be taken into consideration. The background noise of the cell is configured by the BackgroundNoise parameter. For details on how to configure and activate the feature, see the RAN Reconfiguration Guide.

3.2 0.5/0.5 Configuration In 0.5/0.5 configuration mode, one CPRI port supports a maximum of four RRUs, with two RRUs coexisting in one cell. Thus, a maximum of two cells are supported. The two RRUs that are connected to different CPRI ports cannot be configured in one cell. One BBU supports a maximum of six CPRI ports and a maximum of 24 RRUs, with two RRUs coexisting in one cell. Thus, a maximum of 12 cells are supported. In four-channels demodulation mode, the number of cells supported by the WBBPb3 and WBBPb4 boards in the DBS3900 or iDBS3900 decreases from 6 to 3. One WBBPb board (WBBPb1, WBBPb2, WBBPb3, or WBBPb4) supports three CPRI ports and three cells, with two RRUs coexisting in one cell. Thus, a maximum of six RRUs are supported. A hybrid configuration of a cell in 0.5/0.5 configuration mode and an ordinary cell is not recommended. Due to the delay, the length of the interconnection optical cables between the RRUs in the same cell must be less than four kilometers. To activate the 0.5/0.5 configuration mode, configure the parameters as follows: 

Run the MML command ADD SEC, − Configure

the sector type SECT to REMOTE_SECTOR, and then configure the diversity mode DIVM to HALFFREQ(0.5/0.5 Mode).

− Configure

the cover type COVERTYPE.

If the COVERTYPE parameter is set to SAMEZONE (Same Cover Type), two RRUs cover the same area and the total output power of the RRUs equals the output power of the cell. If the COVERTYPE parameter is set to DIFFZONE (Different Cover Type), two RRUs cover different areas and the output power of each RRU equals the output power of the cell.

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WCDMA RAN Multiple RRUs in One Cell 

3 Engineering Guidelines

Configure the antenna magnitude ANTM through the MML command ADD SEC and the demodulation work mode DEMMODE through the MML command ADD ULGROUP. − If

the RRU uses the single-antenna receive mode, set the ANTM parameter to 2(two antennas), and set the DEMMODE to DEM_2_CHAN (2-Channels Demodulation Mode).

− If

the RRU uses the double-antenna receive mode, set the ANTM parameter to 4(four antennas), and set the DEMMODE to DEM_4_CHAN (4-Channels Demodulation Mode).



Run the MML command ADD LOCELL, − Configure

the sector type SECT to REMOTE_SECTOR,

− Configure

the two TX way TTW to False. The cells in 0.5/0.5 configuration mode cannot use the two

TX way. The cells in 0.5/0.5 configuration mode support the high speed access feature. To enable high speed access, set the high speed movement mode HISPM to TRUE. Then, you can specify the speed rate (SPR) for high speed access. For details, see the High Speed Access Feature Parameter Description.

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4 Parameters

4 Parameters Table 4-1 Parameter description Parameter ID

NE

MML Command

Background BSC690 ADD Noise 0 UCELLCAC(Option al) MOD UCELLCAC(Option al)

Meaning Meaning: If [Auto-Adaptive Background Noise Update Switch] is set to OFF, it is used to set background noise of the cell. If [Auto-Adaptive Background Noise Update Switch] is set to ON, new background noise is restricted by this parameter and BgnAbnormalThd. For detailed information of this parameter, refer to the 3GPP TS 25.133. GUI Value Range: 0~621 Actual Value Range: -112~-50, step:0.1 Unit: dBm Default Value: 61

SECT

NodeB MOD Meaning: sector type LOCELL(Mandatory ) GUI Value Range: LOCAL_SECTOR(Local Sector), ADD REMOTE_SECTOR(Remote Sector), LOCELL(Mandatory DIST_SECTOR(Distribute Sector) ) Actual Value Range: LOCAL_SECTOR, REMOTE_SECTOR, DIST_SECTOR Unit: None Default Value: -

SECT

NodeB MOD Meaning: Sector type SEC(Optional) ADD SEC(Optional) GUI Value Range: LOCAL_SECTOR(Local Sector), REMOTE_SECTOR(Remote Sector), DIST_SECTOR(Distribute Sector) Actual Value Range: LOCAL_SECTOR, REMOTE_SECTOR, DIST_SECTOR Unit: None Default Value: LOCAL_SECTOR

DIVM

NodeB ADD SEC(Optional) Meaning: Diversity mode of the sector GUI Value Range: COMMON_MODE(Common Mode), HALFFREQ(Half Frequency) Actual Value Range: COMMON_MODE, HALFFREQ Unit: None Default Value: COMMON_MODE

COVERTYP NodeB ADD SEC(Optional) Meaning: Cover type of the sector E GUI Value Range: SAMEZONE(Same Zone), DIFFZONE(Different Zone) Actual Value Range: SAMEZONE, DIFFZONE Unit: None Default Value: -

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4 Parameters

Parameter ID

NE

MML Command

Meaning

ANTM

NodeB ADD SEC(Optional) Meaning: Magnitude of antennas in the sector GUI Value Range: 1, 2, 4 Actual Value Range: 1, 2, 4 Unit: None Default Value: -

DEMMODE NodeB ADD Meaning: It is the Demodulation Work Mode of the uplink ULGROUP(Mandat resource group. ory) GUI Value Range: DEM_2_CHAN(2-Channels Demodulation Mode), DEM_4_CHAN(4-Channels Demodulation Mode), DEM_ECON_4_CHAN(Economical 4-Channels Demodulation Mode) Actual Value Range: DEM_2_CHAN, DEM_4_CHAN, DEM_ECON_4_CHAN Unit: None Default Value: TTW

NodeB MOD Meaning: Two Tx way of the local cell LOCELL(Optional) ADD GUI Value Range: FALSE(False), TRUE(True) LOCELL(Optional) Actual Value Range: FALSE, TRUE Unit: None Default Value: False

HISPM

NodeB MOD Meaning: High speed movement mode LOCELL(Optional) ADD GUI Value Range: FALSE(False), TRUE(True) LOCELL(Optional) Actual Value Range: FALSE, TRUE Unit: None Default Value: False

SPR

NodeB MOD Meaning: Speed rate LOCELL(Optional) ADD GUI Value Range: 250, 400, 500 LOCELL(Optional) Actual Value Range: 250, 400, 500 Unit: km/h Default Value: -

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5 Counters

5 Counters There are no specific counters associated with this feature.

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6 Glossary

6 Glossary For the acronyms, abbreviations, terms, and definitions, see the Glossary.

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7 Reference Documents

7 Reference Documents None.

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Multiple RRUs in One Cell

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