2-Antenna Receive Diversity(GBSS14.0_01)

2-Antenna Receive Diversity GBSS14.0

Feature Parameter Description

Issue 01

Date 2012-04-28

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 01 (2012-04-28) 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

3.2.4 ADC ................................................................................................................................. 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



5.4 ADC ......................................................................................................................................... 5-2



6 Engineering Guidelines ...................................................................................................... 6-3

6.1 When to Use the Four Algorithms ............................................................................................. 6-3

6.1.1 MRC Algorithm ................................................................................................................ 6-3

6.1.2 ICC Algorithm .................................................................................................................. 6-3

6.1.3 EICC Algorithm ................................................................................................................ 6-3

6.1.4 ADC Algorithm ................................................................................................................. 6-3

6.2 Information to Be Collected ...................................................................................................... 6-3

6.3 Network Planning ..................................................................................................................... 6-4

6.4 Feature Deployment ................................................................................................................. 6-4

6.4.1 Deploying MRC ............................................................................................................... 6-4

6.4.2 Deploying ICC ................................................................................................................. 6-4

6.4.3 Deploying EICC ............................................................................................................... 6-4

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ii

6.5 Performance Optimization ........................................................................................................ 6-4

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

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

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

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

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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:

01 (2012-04-28)

Draft A (2012-02-15)

01 (2012-04-28)

This is the first release of GBSS14.0.

Compared with issue Draft A (2012-02-15) of GBSS14.0, issue 01 (2012-04-28) of GBSS14.0 incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change Added the following chapters:

Chapter 5.4 "ADC"

None

Editorial change Added the following chapters:

Chapter 4 "Related Features"

Chapter 5 "Impact on the Network"

Chapter 6 "Engineering Guidelines"

None

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2-Antenna Receive Diversity 1 Introduction to This Document



1-2

Draft A (2012-02-15)

This is the draft release of GBSS14.0.

Compared with issue 01 (2011-03-31) of GBSS13.0, issue Draft A (2012-02-15) of GBSS14.0 has no change.

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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).

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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.

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, such as over sea coverage.

To enable the MRC algorithm of 2-antenna receive diversity, set ICTYP to MRC(MRC).

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

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2-Antenna Receive Diversity 3 Technical Description



3-2

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.

To enable the ICC algorithm of 2-antenna receive diversity, set ICTYP to ICC(ICC).

A resource item license is required for enabling this algorithm.

3.2.3 EICC

The GBFD-115821 EICC feature 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 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.

Set STIRCALLOWED to YES(Yes) to select the EICC algorithm of 2-antenna receive diversity.

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

This feature can be enabled only after you apply for a resource item license.

3.2.4 ADC

The adaptive diversity combining (ADC) algorithm checks whether an ongoing call is in the interference-limited or noise-limited scenario.

In the interference-limited scenario, the BTS uses EICC.

In the noise-limited scenario, the BTS uses MRC.

The ADC algorithm achieves favorable network performance in noise-limited and interference-limited scenarios.

To enable the ADC algorithm, set ADAICFLAG to ON(On). In addition, you can set ADAICADFLAG to ON(On) to improve the detection accuracy in adaptive scenarios.

If STIRCALLOWED is set to YES(Yes), the ADC algorithm adaptively selects either EICC or MRC.

If STIRCALLOWED is set to NO(No), the ADC algorithm adaptively selects either ICC or MRC.

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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

ADC None None None

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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.

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2-Antenna Receive Diversity 5 Impact on the Network



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5.4 ADC


This algorithm can adaptively select an appropriate combining algorithm based on interference scenarios on the live network. Compared with the fixed combining algorithm, this algorithm further improves the network anti-interference capability and uplink receive quality.




This algorithm can adaptively select an appropriate combining algorithm based on interference scenarios on the live network. Therefore, this algorithm enhances the network anti-interference capability and improves the uplink receive quality.

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2-Antenna Receive Diversity 6 Engineering Guidelines



6-3

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.

6.1.4 ADC Algorithm

Use the ADC algorithm in the following conditions:

It is uncertain whether the live network is in the noise-limited or interference-limited scenario.

Interference scenario changes take place.

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 network frequencies are tightly set.

The network interference is strong and traffic is heavy.

The ADC algorithm improves the uplink performance when:

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The network environment is uncertain or varies with time.

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

6.3 Network Planning

RF Planning

N/A

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 MRC

Activation Procedure

Run the BSC6900 MML command SET GCELLSOFT with ICTYP set to MRC(MRC).

Verification Procedure

Run the BSC6900 MML command LST GCELLSOFT to query the value of ICTYP.

Expected result: If ICTYP is set to MRC(MRC), the MRC function has been enabled.

Deactivation Procedure

Run the BSC6900 MML command SET GCELLSOFT with ICTYP set to ICC(ICC).

6.4.2 Deploying ICC

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

6.4.3 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.

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6-5

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.

If it is uncertain about the network interference scenarios, or interference scenario changes take place, use the ADC algorithm.

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2-Antenna Receive Diversity 7 Parameters



7-1

7 Parameters

Table 7-1 Parameter description

Parameter ID NE Meaning Description

ADAICADFLAG BSC6900 Whether to enable the adaptive interference cancellation enhancement function. If this parameter is set to ON, the adaptive interference cancellation enhancement function is enabled. If this parameter is set to OFF, the adaptive interference cancellation enhancement function is not enabled. It is recommended that this parameter be set to ON when adaptive interference cancellation is used.

Meaning: Whether to enable the adaptive interference cancellation enhancement function. If this parameter is set to ON, the adaptive interference cancellation enhancement function is enabled. If this parameter is set to OFF, the adaptive interference cancellation enhancement function is not enabled. It is recommended that this parameter be set to ON when adaptive interference cancellation is used.

GUI Value Range: OFF(Off), ON(On)

Actual Value Range: OFF, ON

Default Value: OFF(Off)

Unit: None

ADAICFLAG BSC6900 Whether to adaptively select the interference cancellation mode. If this parameter is set to ON, the BSC6900 adaptively selects the interference cancellation mode. If this parameter is set to OFF, the BSC6900 always selects the fixed interference cancellation mode.

Meaning: Whether to adaptively select the interference cancellation mode. If this parameter is set to ON, the BSC6900 adaptively selects the interference cancellation mode. If this parameter is set to OFF, the BSC6900 always selects the fixed interference cancellation mode.

GUI Value Range: OFF(Off), ON(On)

Actual Value Range: OFF, ON

Default Value: OFF(Off)

Unit: None

ICTYP BSC6900 Interference cancellation mode. When tight frequency reuse is used, it is recommended that this parameter be set to ICC. When noises are

Meaning: Interference cancellation mode. When tight frequency reuse is used, it is recommended that this parameter be set to ICC. When noises are restricted, it

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restricted, it is recommended that this parameter be set to MRC.

is recommended that this parameter be set to MRC.

GUI Value Range: MRC(MRC), ICC(ICC)

Actual Value Range: MRC, ICC

Default Value: MRC(MRC)

Unit: None

RCVMD BSC6900 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.

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(Independent Receiver)

Unit: None

STIRCALLOWED BSC6900 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 heavy-traffic network where tight frequency reuse is in place.

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 heavy-traffic network where tight frequency reuse is in place.

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

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Actual Value Range: NO, YES

Default Value: NO(No)

Unit: None

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2-Antenna Receive Diversity 8 Counters



8-1

8 Counters

There are no specific counters associated with this feature.

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2-Antenna Receive Diversity 9 Glossary



9-1

9 Glossary

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

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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

1 Introduction to This Document1.1 Scope1.2 Intended Audience1.3 Change HistoryDocument Issues01 (2012-04-28)Draft A (2012-02-15)

2 Overview3 Technical Description3.1 Technical PrincipleFigure 3-1 Working principle of 2-antenna receive diversity1. 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).

3.2 Diversity Combining Algorithms3.2.1 MRC3.2.2 ICC3.2.3 EICC3.2.4 ADC

4 Related Features5 Impact on the Network5.1 MRC5.1.1 Impact on System Capacity5.1.2 Impact on Network Performance

5.2 ICC5.2.1 Impact on System Capacity5.2.2 Impact on Network Performance

5.3 EICC5.3.1 Impact on System Capacity5.3.2 Impact on Network Performance

5.4 ADC5.4.1 Impact on System Capacity5.4.2 Impact on Network Performance

6 Engineering Guidelines6.1 When to Use the Four Algorithms6.1.1 MRC Algorithm6.1.2 ICC Algorithm6.1.3 EICC Algorithm6.1.4 ADC Algorithm

6.2 Information to Be Collected6.3 Network PlanningRF PlanningNetwork TopologyHardware Planning

6.4 Feature Deployment6.4.1 Deploying MRCActivation ProcedureVerification ProcedureDeactivation Procedure

6.4.2 Deploying ICC6.4.3 Deploying EICC

6.5 Performance OptimizationMonitoringParameter Optimization

7 ParametersTable 7-1 Parameter description

8 Counters9 Glossary10 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