2-Antenna Receive Diversity(_02)

2-Antenna Receive Diversity GBSS13.0

Feature Parameter Description

Issue 02

Date 2012-06-30

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.

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GSM BSS

2-Antenna Receive Diversity Contents

Issue 02 (2012-06-30) Huawei Proprietary and Confidential

Copyright © Huawei Technologies Co., Ltd.

i

Contents

1 Introduction to This Document ......................................................................................... 1-1

1.1 Scope ...................................................................................................................................... 1-1

1.2 Intended Audience ................................................................................................................... 1-1

1.3 Change History ........................................................................................................................ 1-1

2 Overview ................................................................................................................................ 2-1

3 Technical Description.......................................................................................................... 3-1

3.1 Technical Principle ................................................................................................................... 3-1

3.2 Diversity Combining Algorithms ................................................................................................ 3-1

3.2.1 MRC ................................................................................................................................ 3-1

3.2.2 ICC .................................................................................................................................. 3-1

3.2.3 EICC ............................................................................................................................... 3-2

4 Related Features .................................................................................................................. 4-1

5 Impact on the Network ........................................................................................................ 5-1

5.1 MRC ........................................................................................................................................ 5-1

5.1.1 Impact on System Capacity .............................................................................................. 5-1

5.1.2 Impact on Network Performance ...................................................................................... 5-1

5.2 ICC .......................................................................................................................................... 5-1



5.3 EICC ........................................................................................................................................ 5-1



6 Engineering Guidelines ...................................................................................................... 6-1

6.1 When to Use the Four Algorithms ............................................................................................. 6-1

6.1.1 MRC Algorithm ................................................................................................................ 6-1

6.1.2 ICC Algorithm .................................................................................................................. 6-1

6.1.3 EICC Algorithm ................................................................................................................ 6-1

6.2 Information to Be Collected ...................................................................................................... 6-1

6.3 Network Planning ..................................................................................................................... 6-1

6.4 Feature Deployment ................................................................................................................. 6-2

6.4.1 Deploying ICC ................................................................................................................. 6-2

6.4.2 Deploying EICC ............................................................................................................... 6-2

6.5 Performance Optimization ........................................................................................................ 6-2

7 Parameters ............................................................................................................................ 7-1

8 Counters ................................................................................................................................ 8-1

9 Glossary ................................................................................................................................. 9-1

GSM BSS

2-Antenna Receive Diversity Contents



ii

10 Reference Documents..................................................................................................... 10-1

GSM BSS

2-Antenna Receive Diversity 1 Introduction to This Document



1-1

1 Introduction to This Document

1.1 Scope

This document describes the working principle of 2-antenna receive diversity and the diversity combining algorithms.

1.2 Intended Audience

It is assumed that users of this document are familiar with GSM basics and have a working knowledge of GSM telecommunication.

This document is intended for:

Personnel working on Huawei GSM products or systems

System operators who need a general understanding of this feature

1.3 Change History

The change history provides information on the changes between different document versions.

There are two types of changes, which are defined as follows:

Feature change

Feature change refers to the change in the 2-Antenna receive diversity feature of a specific product version.

Editorial change

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:

02 (2012-06-30)

01 (2011-03-31)

Draft A (2011-01-15)

02 (2012-06-30)

This is the second release of GBSS13.0.

Compared with issue 01(2011-03-31) of GBSS13.0, issue 02 (2012-06-30) of GBSS13.0 incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change None None

Editorial change Added the following chapters:

Chapter 4 "Related Features"

Chapter 5 "Impact on the Network"

Chapter 6 "Engineering Guidelines"

None

GSM BSS

2-Antenna Receive Diversity 1 Introduction to This Document



1-2

01 (2011-03-31)

This is the first release of GBSS13.0.

Compared with issue draft A (2011-01-15) of GBSS13.0, issue 01 (2011-03-31) of GBSS13.0 has no change.

Draft A (2011-01-15)

This is the draft release of GBSS13.0.

Compared with issue 01 (2010-06-30) of GBSS12.0, issue Draft A (2011-01-15) of GBSS13.0 has no change.

GSM BSS

2-Antenna Receive Diversity 2 Overview



2-1

2 Overview

In a wireless communications system, the radio signal from the transmitter arrives at the receiver through two or more paths. This phenomenon is called multipath propagation. With multipath propagation, the amplitude, phase, and angle of the received signal change. This phenomenon is called multipath fading. As a result, the quality of the received signal deteriorates. Diversity is one of the techniques used to handle multipath fading in the communications system. It increases the signal-to-noise ratio by superimposing uncorrelated signals.

The diversity technique in GSM involves time diversity, frequency diversity, and space diversity. In the case of space diversity, multiple antennas are used at the receiver to receive uncorrelated signals of the same source (superimposition of uncorrelated signals). In engineering implementation, generally two antennas (or two polarization ends of the same polarization antenna) are used to receive signals. The signals received from the two antennas can be combined in different ways to obtain desired signals, for example, Maximal Ratio Combining (MRC), Interference Cancellation Combining (ICC), and Enhanced Interference Rejection Combining (EICC).

GSM BSS

2-Antenna Receive Diversity 3 Technical Description



3-1

3 Technical Description

3.1 Technical Principle

The 2-antenna receive diversity technique combines the signals received from the two diverse antennas at the receiving end to mitigate multipath interference. Figure 3-1 shows the working principle of 2-antenna receive diversity.

Figure 3-1 Working principle of 2-antenna receive diversity

W1

y(k)

RX channel 1

RX channel 2

x(k)

)(2 kr

)(kr1

)(kS1

)(kS2

W2

Signal

RX signal

RX signal

Noise and

interference

Noise and

interference

As shown in Figure 3-1:

1. The signal x(k) arrives at the diverse antennas through two RX channels. The two RX signals are identified as r1(k) and r2(k). After the superimposition of interference and noise, the two RX signals are identified as S1(k) and S2(k).

2. Based on the maximum signal-to-noise ratio criterion, the adaptive combining coefficients W1 and W2 are calculated and the output signal is obtained through the formula: y(k) = W1 x S1(k) + W2 x S2(k).

The combining algorithms consist of the MRC, ICC, and EICC. In Figure 3-1 the two RX channels correspond to the main and diversity RX channels of the TRX.

You should set RCVMD to MAINDIVERSITY(Main Diversity) to enable the 2-Antenna Receive Diversity feature.

3.2 Diversity Combining Algorithms

3.2.1 MRC

MRC performs weighted combining on the two signals received by the BTS based on their respective signal-to-noise ratios. This combining method is ideal for situations with little interference and limited noise. It is applicable to wide coverage and overseas coverage.

3.2.2 ICC

ICC is a multi-antenna combining technique developed from MRC. In tight frequency reuse scenarios the interfering signals received at diverse antennas may come from the same interfering source. Therefore, a certain correlation exists among these interfering signals. ICC uses this correlation when combining the signals of the two antennas to eliminate certain interference. The use of ICC can improve the speech quality and data throughput in situations with strong interference, for example, the network where tight frequency reuse is in place. ICC can suppress the interference within the GSM system and from other systems if correlation exists between the interfering signals received on diverse antennas.

../RNCParaHtml/mbsc/m-para/gtrxdev_rcvmd.html

GSM BSS

2-Antenna Receive Diversity 3 Technical Description



3-2

A resource item license is required for enabling this algorithm.

3.2.3 EICC

EICC is developed from ICC. Generally, the interfering signals received from multiple antennas are both space correlated (among the antennas) and time correlated. The difference between ICC and EICC is that ICC considers only space correlation to eliminate interference whereas EICC considers both space correlation and time correlation to suppress and eliminate interference. EICC is mainly used in high traffic network where tight frequency reuse is in place and in situations where the noise of a single interfering source is limited. The EICC performs better than ICC. (GBFD-115821 EICC)

You should set STIRCALLOWED to YES to select the EICC algorithm of 2-antenna receive diversity.

When STIRCALLOWED is set to NO, the system selects the ICC algorithm by default.

The EICC algorithm and AFC algorithm are mutually exclusive.

../RNCParaHtml/mbsc/m-para/gcellsoft_stircallowed.html


GSM BSS

2-Antenna Receive Diversity 4 Related Features



4-1

4 Related Features

Feature Prerequisite Feature

Mutually Exclusive Feature Affected Feature

MRC None None None

ICC None None None

EICC None Automatic Frequency Correction (AFC)

NOTE

This feature is disabled automatically after AFC is enabled.

None

GSM BSS

2-Antenna Receive Diversity 5 Impact on the Network



5-1

5 Impact on the Network

5.1 MRC

5.1.1 Impact on System Capacity

This algorithm improves the uplink receive quality.

For CS services, after uplink power control is enabled for MSs, this algorithm decreases the entire network interference and increases the traffic volume.

For PS services, this algorithm increases the uplink throughput.

5.1.2 Impact on Network Performance

This algorithm improves the uplink receive quality.

5.2 ICC


Compared with the MRC algorithm, the ICC algorithm enhances the network anti-interference capability and improves the uplink receive quality.




Compared with the MRC algorithm, the ICC algorithm enhances the network anti-interference capability and improves the uplink receive quality.

5.3 EICC


Compared with the ICC algorithm, the EICC algorithm enhances the network anti-interference capability and improves the uplink receive quality.




Compared with the ICC algorithm, the EICC algorithm enhances the network anti-interference capability and improves the uplink receive quality.

GSM BSS

2-Antenna Receive Diversity 6 Engineering Guidelines



6-1

6 Engineering Guidelines

6.1 When to Use the Four Algorithms

6.1.1 MRC Algorithm

Use the MRC algorithm in the following conditions:

The live network is in noise-limited scenarios, for example, railway coverage or rural area coverage.

The licenses for the ICC and EICC algorithms have not been obtained.

6.1.2 ICC Algorithm

Use the ICC algorithm in the following conditions:

The live network is in interference-limited scenarios, for example, urban area coverage and tight frequency reuse scenarios with strong interference.

The license for the EICC algorithm has not been obtained.

6.1.3 EICC Algorithm

You are advised to use the EICC algorithm in interference-limited scenarios, such as city coverage and tight frequency reuse scenarios with strong interference.

6.2 Information to Be Collected

Before deploying this feature, collect the following information:

Whether the cell is configured in 2-antenna receive mode

Frequency planning data

Cell coverage range

Traffic volume on the network

Whether there is interference in the radio environment

The MRC algorithm improves the network performance at the coverage edge when:

The cell is configured in 2-antenna receive mode.

The network frequencies are loosely set.

The cell coverage is relatively large.

The ICC and EICC algorithms improve the network anti-interference capability when:

The cell is configured in 2-antenna receive mode.

The network frequencies are tightly set.

The network interference is strong and traffic is heavy.

These three algorithms are not applicable to cells in one-antenna receive mode.

6.3 Network Planning

RF Planning

N/A

GSM BSS

2-Antenna Receive Diversity 6 Engineering Guidelines



6-2

Network Topology

N/A

Hardware Planning

The two RX channels of the TRXs must be connected to two antennas, or connected to a dual-polarized antenna.

6.4 Feature Deployment

6.4.1 Deploying ICC

For details about how to activate, verify, and deactivate this algorithm, see Configuring ICC.

6.4.2 Deploying EICC

For details about how to activate, verify, and deactivate this algorithm, see Configuring EICC.

6.5 Performance Optimization

Monitoring

Observe network counters. For CS services, observe Uplink Quality (UL RxQual). If the counter deteriorates or remains unchanged after the 2-antenna receive diversity feature has been enabled, adjust the combining algorithms.

Parameter Optimization

The ICC algorithm achieves favorable network performance in most scenarios. For scenarios without interference, the MRC algorithm is recommended. For scenarios with tight frequency reuse, heavy traffic, and strong interference, the EICC algorithm is recommended.

../FAGHtml/mbsc/m-bsc-reconfiguration-guide/GBFD-115801.html

../FAGHtml/mbsc/m-bsc-reconfiguration-guide/GBFD-115821.html

GSM BSS

2-Antenna Receive Diversity 7 Parameters



7-1

7 Parameters

Table 7-1 Parameter description

Parameter ID NE MML Command Feature ID Feature Name

Description

RCVMD BSC6900

SET GTRXDEV(Optional)

MRFD-210301

Configuration Management

Meaning: RF receive mode of the TRX.

The BTS3012, BTS3012AE, BTS3012II, BTS3006C, and BTS3002E do not support Main Diversity.

The DBS3900 GSM and BTS3900 GSM support Four Diversity Receiver and Main Diversity.

GUI Value Range: INDEPENDENT(Independent Receiver), DIVIDING(Dividing Receiver), FOURDIVERSITY(Four Diversity Receiver), MAINDIVERSITY(Main Diversity), NONE(None)

Actual Value Range: INDEPENDENT, DIVIDING, FOURDIVERSITY, MAINDIVERSITY, NONE

Default Value: INDEPENDENT

Unit: None

STIRCALLOWED

BSC6900

SET GCELLSOFT(Optional)

GBFD-115821

EICC Meaning: Whether to enable the EICC algorithm. Enhanced Interference Rejection Combining combines the signals received by multiple antennas to obtain better signals. EICC is mainly used in high traffic network where tight frequency reuse is in place.

GUI Value Range: NO(No), YES(Yes)

Actual Value Range: NO, YES

Default Value: NO

../RNCParaHtml/mbsc/m-para/gtrxdev_rcvmd.html

../RNCParaHtml/mbsc/m-mml/set-gtrxdev.html

../RNCParaHtml/mbsc/m-mml/set-gtrxdev.html



../RNCParaHtml/mbsc/m-mml/set-gcellsoft.html



GSM BSS

2-Antenna Receive Diversity 7 Parameters



7-2

Parameter ID NE MML Command Feature ID Feature Name

Description

Unit: None

GSM BSS

2-Antenna Receive Diversity 8 Counters



8-1

8 Counters

There are no specific counters associated with this feature.

GSM BSS

2-Antenna Receive Diversity 9 Glossary



9-1

9 Glossary

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

Glossary.htm

GSM BSS

2-Antenna Receive Diversity 10 Reference Documents



10-1

10 Reference Documents

[1] 3GPP TS 25.101, "User Equipment (UE) radio transmission and reception (FDD)"

[2] 3GPP TS 25.211, "Physical channels and mapping of transport channels onto physical channels (FDD)"

[3] 3GPP TS 25.306, " UE Radio Access capabilities "

[4] 3GPP TS 25.308, "UTRA High Speed Downlink Packet Access (HSPDA); Overall description"

[5] 3GPP TS 25.321, "Medium Access Control (MAC) protocol specification"

[6] BSC6900 Feature List

[7] BSC6900 Basic Feature Description

[8] BSC6900 GSM Parameter Reference

[9] BSC6900 GSM MML Command Reference