35 tx rx diversity

RAN Feature Description Table of Contents

Table of Contents

Chapter 35 TX/RX Diversity......................................................................................................35-135.1 Introduction..................................................................................................................35-1

35.1.1 Definition...........................................................................................................35-135.1.2 Purposes...........................................................................................................35-135.1.3 Terms and Abbreviations...................................................................................35-1

35.2 Availability....................................................................................................................35-235.2.1 Network Elements Required..............................................................................35-235.2.2 Software Release..............................................................................................35-335.2.3 Miscellaneous....................................................................................................35-3

35.3 Impact..........................................................................................................................35-435.3.1 On the System Performance.............................................................................35-435.3.2 On Other Features.............................................................................................35-4

35.4 Technical Description...................................................................................................35-435.4.1 TX/RX Diversity Configuration Model................................................................35-435.4.2 RX Diversity Algorithms.....................................................................................35-635.4.3 TX Diversity Algorithms...................................................................................35-11

35.5 Capabilities................................................................................................................35-2635.6 Implementation..........................................................................................................35-27

35.6.1 Enabling TX/RX Diversity................................................................................35-2735.6.2 Reconfiguring TX/RX Diversity Parameters.....................................................35-2835.6.3 Disabling TX/RX diversity................................................................................35-28

35.7 Maintenance Information............................................................................................35-2835.7.1 Alarms.............................................................................................................35-2835.7.2 Counters..........................................................................................................35-28

35.8 References................................................................................................................. 35-29

Huawei Technologies Proprietary

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RAN Feature Description List of Figures

List of Figures

Figure 35-1 TX/RX Diversity configuration model (1)..........................................................35-5

Figure 35-2 TX/RX Diversity configuration model (2)..........................................................35-5

Figure 35-3 RX diversity implementation of one sector in BTS3812E...............................35-10

Figure 35-4 RX diversity implementation of one sector in DBS3800.................................35-11

Figure 35-5 TX diversity implementation of one sector in BTS3812E...............................35-20

Figure 35-6 TX diversity implementation of one sector in DBS3800.................................35-21

Figure 35-7 Structure of SCH transmitted in TSTD...........................................................35-21

Figure 35-8 STTD transmitter...........................................................................................35-22

Figure 35-9 Transmitter and receiver in closed loop transmit diversity mode....................35-23


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RAN Feature Description List of Tables

List of Tables

Table 35-1 NEs required for TX/RX diversity....................................................................35-3

Table 35-2 RAN products and related versions...................................................................35-3

Table 35-3 BTS3812E subrack information.........................................................................35-8

Table 35-4 DBS3800 subrack information...........................................................................35-9

Table 35-5 Application of TX diversity modes on downlink physical channel types...........35-11

Table 35-6 BTS3812E subrack information.......................................................................35-14

Table 35-7 BTS3812E board information..........................................................................35-15

Table 35-8 DBS3800 subrack information.........................................................................35-18


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RAN Feature Description Chapter 35 TX/RX Diversity

Chapter 35 TX/RX Diversity

35.1 Introduction

35.1.1 Definition

Signals received on radio channels are combined multipath components that reach the receiver. The signal from individual paths, if combined by the receiver, can combat fading.

Diversity is a transmission technique that enables individual signals to be combined to enhance system performance.

In the WCDMA system, diversity can be performed in two directions:

Receive diversity Transmit diversity

Based on the number of antennas, receive diversity is of two types:

2-way receive diversity 4-way receive diversity

Based on the feedback, transmit diversity is of two types:

Open loop transmit diversity (without feedback) Closed loop transmit diversity (with feedback)

Open loop transmit diversity can be further categorized into:

Space Time Transmit Diversity (STTD) Time Switched Transmit Diversity (TSTD)

35.1.2 Purposes

Diversity can improve the performance of RX channels and lower the SIR requirements for downlink signals and uplink signals.

35.1.3 Terms and Abbreviations

I. Terms

None.


1


II. Abbreviations

Abbreviation Full Spelling

AICH Acquisition Indicator Channel

CLD Closed Loop Transmit Diversity

CLD1 Closed Loop Transmit Diversity Mode 1

DPCCH Dedicated Physical Control Channel

DPCH Dedicated Physical Channel

E-AGCH E-DCH Absolute Grant Channel

E-DCH Enhanced Dedicated Channel

E-HICH E-DCH Hybrid ARQ Indicator Channel

E-RGCH E-DCH Relative Grant Channel

HS-PDSCH High Speed Physical Downlink Shared Channel

HS-SCCH Shared Control Channel for HS-DSCH

MICH MBMS Indicator Channel

PA Power Amplifier

P-CCPCH Primary Common Control Physical Channel

PICH Page Indicator Channel

PDSCH Physical Downlink Shared Channel

RNC Radio Network Controller

RX Diversity Receive Diversity

S-CCPCH Secondary Common Control Physical Channel

SCH Synchronization Channel

SIR Signal-to-Interference Ratio

SNR Signal-to-Noise Ratio

STTD Space Time Transmit Diversity

TSTD Time Switched Transmit Diversity

TX Diversity Transmit Diversity


2


Abbreviation Full Spelling

UE User Equipment

35.2 Availability

35.2.1 Network Elements Required

Table 35-1 shows the Network Elements (NEs) required for TX/RX diversity.

Table 35-1 NEs required for TX/RX diversity

UE NodeB RNC MSC Server MGW SGSN GGSN HLR

√ √ √ – – – – –

Note:

–: not required

√: required

35.2.2 Software Release

Table 35-2 describes the versions of RAN products that support TX/RX diversity.

Table 35-2 RAN products and related versions

Product Version

RNC BSC6800 V100R002 and later releases

NodeB

DBS3000 V100R006 and later releases

BTS3812A V100R005 and later releases

BTS3812E V100R005 and later releases


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Note:

The RNC supports TSTD and STTD from V100R002 and it will support CLD mode 1 from V100R008.

Receive diversity is performed by only the NodeB to improve the performance of RX channels. It does not involve RNC or UE.

35.2.3 Miscellaneous

RX diversity requires the NodeB to provide enough RF channels and demodulation resources that can match the number of diversity antennas. It has no special requirements for RNC or UE.

TX diversity requires the NodeB to provide RF channel resources two times those of no TX diversity mode and to support STTD, TSTD, and CLD1. In TX diversity mode, the UE must support diversity reception, STTD, TSTD, and CLD1. This diversity mode has no special requirements for RNC.

35.3 Impact

35.3.1 On the System Performance

TX diversity can improve terminal performance in special circumstances, especially where there is less valid multipath effect and the UE speed is low. In such a scenario, capacity and coverage can be obviously improved and investment can be reduced while the same QoS is guaranteed and the CAPEX and OPEX can be cut down by operators.

Because there are different scenarios and motion velocities, TX diversity does not have versatility to all users with performance improvement. Whole system gain may be obvious. On the other hand, if different TX modes are set according to different cell circumstances, the handover between cells in different TX modes is complicated. The system may be decreased because of the complexity.

35.3.2 On Other Features

None.

35.4 Technical Description

35.4.1 TX/RX Diversity Configuration Model

The configuration model of TX/RX diversity is show in Figure 35-2 and Figure 35-3.


4


NodeB

CellClass

SEC.Class

Antenna Magnitude

Antenna Channel No.1

Cabinet No. of Antenna Channel1

Subrack No. of Antenna Channel1

Diversity Mode

LOCELL.Class



Slot No. of Power Amplifier1



Slot No. of Power Amplifier2

Cabinet No. of Power Amplifier1

Subrack No. of Power Amplifier1

Cabinet No. of Power Amplifier2

Subrack No. of Power Amplifier2

Figure 35-2 TX/RX Diversity configuration model (1)

CELLSETUP.Class

STTD support indicator

CP1 support indicator

DPCH priority Tx diversity mode

Hspdsch priority Tx diversity

Closed loop time adjust mode indication

Closed loop time adjust mode

TX diversity ind

RNC

NodeBRelatedClass

RadioClass

Figure 35-3 TX/RX Diversity configuration model (2)


5


35.4.2 RX Diversity Algorithms

I. Rake Receiver and Diversity Reception

A rake receiver is a radio receiver designed to counter the effects of multipath fading. It does this by using several "sub-receivers" each delayed slightly in order to tune in to the individual multipath components. Each component is decoded independently, but at a later stage combined in order to make the most use of the different transmission characteristics of each transmission path. This could very well result in higher SNR (or Eb/No) in a multipath environment than in a "clean" environment.

Diversity reception refers to a technique of monitoring multiple frequencies from the same signal source, or multiple radios and antennas monitoring the same frequency, in order to combat signal fade and interference.

II. Implementation of Diversity Reception

Diversity reception is one way to enhance the reception performance of uplink channels. It does not involve RNC or UE.

Huawei NodeBs support both RX diversity and no RX diversity. In RX diversity mode, the NodeB can be configured with 2 antenna (2-way), 4 antennas (4-way), and 4 antennas for economical purpose (4-way economical) through the Antenna Magnitude parameter. The only difference between 4-way and 4-way economical modes is that in the latter mode signals on the random access channel are received from two antennas, which ensures that the maximum coverage of 180 km is achieved.

In RX diversity mode, the NodeB does not require additional devices and works with the same algorithms. Compared with 1-way no RX diversity, 2-way RX diversity requires twice the number of RX channels. Similarly, 4-way RX diversity requires twice the number of RX channels compared with 2-way RX diversity. The number of RX channels depends on the settings of the antenna connectors on the cabinet top.

If Antenna Magnitude is set to no RX diversity, configure only the Antenna Channel No.1 parameter.

If Antenna Magnitude is set to 2-way RX diversity, configure the Antenna Channel No.1 and Antenna Channel No.2 parameters.

If Antenna Magnitude is set to 4-way RX diversity, configure the Antenna Channel No.1, Antenna Channel No.2, Antenna Channel No.3, and Antenna Channel No.4 parameters, cabinet number (Cabinet No. of Antenna Channel1, Cabinet No. of Antenna Channel2, Cabinet No. of Antenna Channel3, and Cabinet No. of Antenna Channel4), and subrack number (Subrack No. of Antenna Channel1, Subrack No. of Antenna Channel2, Subrack No. of Antenna Channel3, and Subrack No. of Antenna Channel4).


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http://www.answers.com/topic/interference

http://www.answers.com/topic/fading

http://www.answers.com/topic/frequency

http://www.answers.com/topic/eb-no

http://www.answers.com/topic/transmission-telecommunications

http://www.answers.com/topic/multipath

http://www.answers.com/topic/receiver-radio

http://www.answers.com/topic/radio


Parameter Name Antenna Magnitude

Parameter ID ANTM

GUI Range 1, 2, 4

Physical Range & Unit1, 2, 4

Unit: none

Default Value None

Optional/Mandatory Mandatory

MML Command ADD SEC MOD SEC

Description:

This parameter defines the number of receiving antennas in a sector.


7


Parameter Name Antenna Channel No.1

Parameter ID ANT1N

GUI Range

For the BTS3812E:

N0A (Cabinet No.0A Ant.), N0B (Cabinet No.0B Ant.), N1A (Cabinet No.1A Ant.), N1B (Cabinet No.1B Ant.), N2A (Cabinet No.2A Ant.), N2B (Cabinet No.2B Ant.), N3A (Cabinet No.3A Ant.), N3B (Cabinet No.3B Ant.), N4A (Cabinet No.4A Ant.), N4B (Cabinet No.4B Ant.), N5A (Cabinet No.5A Ant.), N5B (Cabinet No.5B Ant.), R0A (RRU No. 0A Ant.), R0B (RRU No. 0B Ant.)

For the DBS3800:

R0A (RRU No. 0A Ant.), R0B (RRU No. 0B Ant.), R1A (RRU No. 1A Ant.), R1B (RRU No. 1B Ant.)

Physical Range & UnitSame as above

Unit: none

Default Value None



Description:

This parameter defines the numbered antenna connectors on the cabinet top that are associated with receiving antenna 1 of a sector.


8


Parameter Name Cabinet No. of Antenna Channel1

Parameter ID ANT1CN

GUI Range MASTER (master cabinet)

Physical Range & UnitMASTER

Unit: none

Default Value MASTER



Description:

This parameter defines the numbered cabinet that is associated with receiving antenna 1 of a sector.

Parameter Name Subrack No. of Antenna Channel1

Parameter ID ANT1SRN

GUI RangeFor the BTS3812E, refer to Table 35-1.

For the DBS3800, refer to Table 35-2.


Unit: none

Default ValueBTS3812E: 3

DBS3800: None



Description:

This parameter defines the numbered subracks that are associated with receiving antenna 1 of a sector.


9


Table 35-1 BTS3812E subrack information

Subrack No. Subrack Type

0 Baseband Subrack (BB)

1 Fan Subrack (FAN)

2 Transmitting and Receiving Unit Subrack (TRU)

3 Antenna Filter Unit Subrack (AFU)

6 Extension Subrack (EXT)

20–199 RRU Subrack (RRU)

Table 35-2 DBS3800 subrack information


0–3 BBU Subrack (BBU3806)

0–1 BBU Subrack (BBU3806C)



The parameters Antenna Channel No.2, Antenna Channel No.3, and Antenna Channel No.4 are defined in a way similar to Antenna Channel No.1. They define the numbered antenna connectors associated with receiving antenna 2, 3, and 4 of a sector.

The parameters Cabinet No. of Antenna Channel2, Cabinet No. of Antenna Channel3, and Cabinet No. of Antenna Channel4 are defined in a way similar to Cabinet No. of Antenna Channel1. They define the numbered cabinet associated with receiving antennas 2, 3, and 4 of a sector.

The parameters Subrack No. of Antenna Channel2, Subrack No. of Antenna Channel3, and Subrack No. of Antenna Channel4 are defined in a way similar to Subrack No. of Antenna Channel1. They define the numbered subracks associated with receiving antennas 2, 3, and 4 of a sector.

All these parameters are optionally set.

The hardware configurations of 4-way Rx diversity per sector for different NodeB are as show in Figure 35-4 and Figure 35-5:


10


AN

T

AN

T RX

RET

MON_ANT

COM/PWR

RXA0

RXA1

RXB

TX

MAFU0

AN

T

AN

T RX

RET

MON_ANT

COM/PWR

RXA0

RXA1

RXB

TX

MAFU1

COM

TX

RXA

RXB

BBIF0

BBIF1

PWR

COM

TX

RXA

RXB

BBIF0

BBIF1

PWR

MTRU0 MTRU1

TX/RX0 RX1 RX2 RX3

F1F2

F1F2

F1F2

F1F2

Figure 35-4 RX diversity implementation of one sector in BTS3812E


11


RX filterDUP

LNA0

LNA1

MTRX

TX/RX0

RRU0

LNA0

LNA1

MTRX

RRU1

LNA

1-IN

LNA

0-O

UT

RX filterDUP

LNA

1-IN

LNA

0-O

UTRX1 RX2 RX3

F1F2

F1F2

F1F2

F1F2

HPA

HPA

Figure 35-5 RX diversity implementation of one sector in DBS3800

35.4.3 TX Diversity Algorithms

There are several transmit diversity modes adopted in WCDMA 3GPP, which are TSTD, STTD, and CLD1. TSTD and STTD are open loop transmit diversity, which do not need feedback information compared with the closed loop diversity. Table 35-1 summarizes the possible application of open and closed loop transmit diversity modes on different types of downlink physical channels.

Table 35-1 Application of TX diversity modes on downlink physical channel types

Physical Channel TypeOpen Loop Mode Closed Loop Mode

TSTD STTD Mode 1

P-CCPCH – X –

SCH X – –

S-CCPCH – X –

DPCH – X X

F-DPCH – X –


12


Physical Channel TypeOpen Loop Mode Closed Loop Mode

TSTD STTD Mode 1

PICH – X –

MICH – X –

HS-PDSCH – X X

HS-SCCH – X –

E-AGCH – X –

E-RGCH – X –

E-HICH – X –

AICH – X –

Note: X: applicable

–: not applicable

If a cell works in TX diversity mode, the CPICH, PCCPCH, and SCH channels of the cell must work in TX diversity mode too.

If a cell works in TX diversity mode, the TX diversity ind parameter is set on the RNC and the Diversity Mode parameter is set on the NodeB.

Parameter Name TX diversity ind

Parameter ID TXDIVERSITYIND

GUI Range TRUE, FALSE

Physical Range & UnitTRUE, FALSE

Unit: none

Default Value None

Optional/Mandatory Optional

MML Command MOD CELLSETUP

Description:

This parameter defines the configuration of TX diversity on the downlink common physical channels of a cell.


13


Configuration Rule and Restriction:

If the downlink common channels of a cell is configured on the RNC to support TX diversity mode, ensure that the associated local cell of the NodeB supports TX diversity.

Parameter Name Diversity Mode

Parameter ID DIVM

GUI RangeNO_TX_DIVERSITY (No Transmit Diversity), TX_DIVERSITY (Transmit Diversity), HALFFREQ (0.5/0.5 Mode)

Physical Range & UnitNO_TX_DIVERSITY, TX_DIVERSITY, HALFFREQ

Unit: none

Default Value NO_TX_DIVERSITY



Description:

This parameter defines the configuration of TX diversity in a sector.

When setting up the sectors of the NodeB, you can set only the Diversity Mode parameter. The RF channels to be used are defined by the following parameters when local cells are set up on the NodeB, either BTS3812E or DBS3800.

For the BTS3812E, configure the following parameters of the local cells.


14



Parameter ID ANT1CN



Unit: none



MML Command ADD LOCELL MOD LOCELL

Description:

This parameter defines the numbered cabinet associated with the PAs in the main path when the sector works in no TX diversity or TX diversity mode.



GUI Range Refer to Table 35-2.


Unit: none

Default Value None



Description:

This parameter defines the numbered subrack associated with the MTRU/RRU PAs in the main path when the sector works in no TX diversity or TX diversity mode.


15


Table 35-2 BTS3812E subrack information


0 Baseband Subrack (BB)

1 Fan Subrack (FAN)

2 Transmitting and Receiving Unit Subrack (TRU)

3 Antenna Filter Unit Subrack (AFU)



Parameter Name Slot No. of Power Amplifier1

Parameter ID SN1



Unit: none

Default Value None



Description:

This parameter defines the numbered slots that are associated with the MTRU PAs in the main path when the sector works in no TX diversity or TX diversity mode. You do not need to define the slot number if the RRU is used.


16


Table 35-3 BTS3812E board information

Cabinet No.

Subrack No.

Slot No. Board Type

0 0 0, 1

NBBI (NodeB Baseband Processing and Interface Unit)

NBOI (NodeB Baseband Processing and Optical Interface Unit)

HBBI (NodeB HSDPA Baseband Processing and Interface Unit)

HBOI (NodeB HSDPA Baseband Processing and Optical Interface Unit)

0 0 2–7HULP (NodeB HSDPA Supported Uplink Processing Unit)

0 0 8, 9

NDLP (NodeB Downlink Processing Unit)

HDLP (NodeB HSDPA Supported Downlink Processing Unit

0 0 10, 11NMPT (NodeB Main Processing & Timing Unit)

0 0 12, 13

NDTI (NodeB Digital Trunk Interface Unit)

NUTI (NodeB Universal Transport Interface Unit)

NAOI (NodeB ATM Optical Interface Unit

0 0 14NUTI (NodeB Universal Transport Interface Unit)

0 0 15

HBOI (NodeB HSDPA Baseband Processing and Optical Interface Unit)

NBOI (NodeB Baseband Processing and Optical Interface Unit)

0 0 16 NMON (NodeB Monitor Unit)

0 1 0 NFAN (NodeB Fan Box)

0 2 0–5MTRU (NodeB Multi-Carrier Transceiver Unit)

0 3 0–5MAFU (NodeB Multi-Carrier Antenna Filter Unit)


17


Cabinet No.

Subrack No.

Slot No. Board Type

0 6 0NEMU (NodeB Environment Monitoring Unit)

0 6 2 NGRU (NodeB GPS Receiver)

0 20–199 0 MRRU (Remote Radio Unit)


Parameter ID ANT2CN

GUI Range MASTER (Master cabinet)


Unit: none




Description:

This parameter defines the numbered cabinet associated with the PAs in the diversity path when the sector works in TX diversity mode.


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Unit: none

Default Value None



Description:

This parameter defines the numbered subrack associated with the MTRU/RRU PAs in the diversity path when the sector works in TX diversity mode.

Parameter Name Slot No. of Power Amplifier2

Parameter ID SN2



Unit: none

Default Value None



Description:

This parameter defines the numbered slots that are associated with the MTRU PAs in the diversity path when the sector works in TX diversity mode. You do not need to define the slot number if the RRU is used.

For the DBS3800, configure the following parameters of the local cells.


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Parameter Name Cabinet No. of Power Amplifier1

Parameter ID CN1



Unit: none




Description:

This parameter defines the numbered cabinet associated with the PAs in the main path when the sector works in no TX diversity or TX diversity mode.

Parameter Name Subrack No. of Power Amplifier1

Parameter ID SRN1



Unit: none

Default Value None



Description:

This parameter defines the numbered subrack associated with the MTRU/RRU PAs in the main path when the sector works in no TX diversity or TX diversity mode.


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Table 35-4 DBS3800 subrack information

Subrack No. Subrack type

0–3 BBU Subrack (BBU3806)

0–1 BBU Subrack (BBU3806C)



Parameter Name Cabinet No. of Power Amplifier2

Parameter ID CN2



Unit: none




Description:

This parameter defines the numbered cabinet associated with the PAs in the diversity path when the sector works in TX diversity mode.


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Parameter Name Subrack No. of Power Amplifier2

Parameter ID SRN2



Unit: none

Default Value None



Description:

This parameter defines the numbered subrack associated with the MTRU/RRU PAs in the diversity path when the sector works in TX diversity mode.

If a sector works in 2-way RX diversity mode and TX diversity is performed, you must set up the following hardware connections:

If two pairs of MTRUs and MAFUs are used to implement TX diversity, you must cross-connect them as follows:

- RXA1 on MAFU0 connects to RXB on MTRU1.

- RXA1 on MAFU1 connects to RXB on MTRU0.

- RXBs on both MAFUs work in suspended state.

If two RRUs are used to implement TX diversity, jumpers for cross-connection are required.


22


AN

T

AN

T RX

RET

MON_ANT

COM/PWR

RXA0

RXA1

RXB

TX

MAFU0

AN

T

AN

T RX

RET

MON_ANT

COM/PWR

RXA0

RXA1

RXB

TX

MAFU1

COM

TX

RXA

RXB

BBIF0

BBIF1

PWR

COM

TX

RXA

RXB

BBIF0

BBIF1

PWR

MTRU0 MTRU1

TX/RX0 RX1

F1F2

F1F2

Figure 35-6 TX diversity implementation of one sector in BTS3812E


23


RX filterDUP

LNA0

LNA1

MTRX

RRU0

RX filterDUP

LNA0

LNA1

MTRX

RRU1

TX/RX0

LNA

1-IN

LNA

0-O

UT

LNA

1-IN

LNA

0-O

UTRX1

F1F2

F1F2

HPA

HPA

Figure 35-7 TX diversity implementation of one sector in DBS3800

I. Time Switched Transmit Diversity

TSTD is applied on SCH only. In TSTD, the transmission is switched between different antennas with a known periodicity, as shown in Figure 35-8.

Antenna 1

Antenna 2

acsi,0

acp

acsi,1

acp

acsi,14

acp

Slot #0 Slot #1 Slot #14

acsi,2

acp

Slot #2

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

(Tx OFF)

Figure 35-8 Structure of SCH transmitted in TSTD

TSTD is the simplest transmit diversity mode in WCDMA. The UE can receive TSTD signals with the same method as used in non-diversity mode. In this sense, the UE does not need to be aware if whether TSTD is applied or not.


24


II. Space Time Transmit Diversity

STTD is defined for two antennas. Assume that and are odd and even symbols

respectively. Then the transmissions over two antennas are shown in Figure 35-9.

S1S0

S1S0

S0*-S1

*

Antenna1

Antenna2

Figure 35-9 STTD transmitter

The received symbol may be represented in vector form as follows:

1*01101

0*11000

nShShr

nShShr

The received symbol is decoded over two consecutive time epochs with the following formula:

1*0

*011

*110

*00

ˆ

ˆ

rhrhS

rhrhS

The channel estimation is performed over pilot signals. Then the output is as follows:

1*0

*011

21

201

*110

*00

21

200

)|||(|ˆ)|||(|ˆ

nhnhShhS

nhnhShhS

On the RNC, you can set the STTD support indicator parameter for the cell that may work in STTD mode. If the cell works in STTD mode, you can set open loop transmit diversity for DPCH.


25


Parameter Name STTD support indicator

Parameter ID STTDSUPIND

GUI Range STTD Supported, STTD not Supported

Physical Range & UnitSTTD Supported, STTD not Supported

Unit: none

Default Value None



Description:

This parameter defines the STTD setting of a cell.


If a cell is configured to work in CLD1, ensure that the associated local cell at the NodeB side supports TX diversity.

III. Closed Loop Transmit Diversity

Closed loop transmit diversity is a technique in which the UE, a mobile station, periodically sends quantized estimations of the optimal transmit weights (so called feedback information in WCDMA) to the NodeB, a base station, through the uplink DPCCH channel. The transmitter weights are optimized to deliver maximum power to the UE. Figure 35-10 depicts the concept of closed loop transmit diversity.


26


Antenna1

Antenna2

S w1

w1

Esti mate w1 andw2 f rom pi l ots Demod Srecei ved

si gnal

Send w1 and w2to Base Stati on

Base Stati on

Mobi l e Stati on

Figure 35-10 Transmitter and receiver in closed loop transmit diversity mode

A channel model with a single path is considered and the channel fading factors from two transmitting antennas is denoted h1(t) and h2(t). Assume that the paths from two antennas are so closely spaced in time of arrival at the UE that they are indistinguishable. If time subscripts are ignored, the signals that the UE receives will be as follows:

nSww

hhr

2

121 ][ = hwS + n

The UE calculates the weights at regular intervals from the information h obtained through pilot signals to maximize the received signal power. These weights are quantized and then feedback is given to the NodeB on the reverse link control channel.

If one assumes that the feedback mechanism in closed loop transmit diversity perfectly tracks the channel conditions of the downlink, the Signal-to-Noise Ratio (SNR) after demodulation and channel estimation is bounded as follows:

0

||||0||||

|||| 22

21

2

22

21

22

21

NEshh

NEs

hh

hhSNRcld

Es/N0 is the symbol of SNR that is based solely on transmit signal energy. In comparison, from the STTD section it can be seen that the maximum achievable SNR of STTD is:


27


02|||| 2

22

1

NEshh

SNRsttd

Obviously, the maximum SNR of STTD cannot be greater than the maximum SNR of closed loop transmit diversity.

However, due to availability limitation of feedback capacity (In WCDMA, the feedback capacity is 1500b/s.), the transmit weights may not be able to track the channel conditions of the downlink perfectly, which will most probably occur when the UE moves at a high velocity. In addition, feedback information errors also deteriorate the performance of closed loop transmit diversity. Generally, closed loop transmit diversity provides the biggest gain in low velocities, while open loop methods are robust in high velocities and provides comparatively smaller gain in low velocities.

On the RNC, you can set the CP1 support indicator parameter for the cell that may work in closed loop transmit diversity mode. If the cell works in CLD1, you can set CLD1 for DPCH.

Parameter Name CP1 support indicator

Parameter ID CP1SUPIND

GUI Range CP1 Supported, CP1 not Supported

Physical Range & UnitCP1 Supported, CP1 not Supported

Unit: none

Default Value None



Description:

This parameter defines the CLD1 setting of a cell.


If a cell is configured to work in CLD1, ensure that the associated local cell at the NodeB side supports TX diversity.

If the cell can work in TX diversity mode, you can set two parameters (DPCH priority Tx diversity mode and Hspdsch priority Tx diversity) for the transmit diversity


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settings of the DPCH on the RNC. The DPCH priority Tx diversity mode parameter defines the preferable transmit diversity mode of a cell when services are carried on DPCH. The Hspdsch priority Tx diversity parameter defines the preferable transmit diversity mode of the associated DPCH when services are carried on HSDPA cells.

Parameter Name DPCH priority Tx diversity mode

Parameter ID DPCHPRIOTXDIVERSITYMODE

GUI Range None, STTD, CP1

Physical Range & UnitNone, STTD, CP1

Unit: none

Default Value None



Description:

This parameter defines the preferable transmit diversity mode of DPCH.

Parameter Name Hspdsch priority Tx diversity

Parameter ID HSPDSCHPRIOTXDIVERSITYMODE

GUI Range None, STTD, CP1

Physical Range & UnitNone, STTD, CP1

Unit: none

Default Value None



Description:

This parameter defines the preferable transmit diversity mode of DPCH when HSDPA services are accessed.

For CLD1, the 3GPP defines two modes to report closed loop feedback information: j+1 and j+2. In j+1 mode, the feedback information of timeslot j is reported after the


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first (j+1)mod15 timeslot. In j+2 mode, the feedback information of timeslot j is reported after the first (j+2)mod15 timeslot.

The modes are set on the RNC through two parameters: Closed loop time adjust mode indication and Closed loop time adjust mode. If the Closed loop time adjust mode indication parameter is set to FALSE, the NodeB processes the feedback information in j+1 mode by default.

Parameter Name Closed loop time adjust mode indication

Parameter ID CLTAMODEIND

GUI Range TRUE, FALSE

Physical Range & UnitTRUE, FALSE

Unit: none

Default Value None



Description:

This parameter defines the setting of closed loop time adjustment mode of a cell.

Parameter Name Closed loop time adjust mode

Parameter ID CLOSEDLOOPTIMEADJUSTMODE

GUI Range OFFSET1, OFFSET2

Physical Range & UnitOFFSET1 = (j+1)mod15; OFFSET2 = (j+2)mod15

Unit: slot

Default Value None



Description:

This parameter defines the time taken to adjust the phase and amplitude of DL dedicated channel upon reception of response from UL dedicated channel.


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35.5 CapabilitiesNone

35.6 Implementation

35.6.1 Enabling TX/RX Diversity

I. Install Hardware

None.

II. Install Software

None.

III. Configure Data

To configure the data on the RNC, perform the following steps:

2) Use the ADD QUICKCELLSETUP command to quickly set up a cell.

During the quick set up of the cell, most parameters are set with their default values, which speeds up the setup procedure.

3) Use the MOD CELLSETUP command to modify TX diversity parameters of the cell.

4) Use the ACT CELL command to activate the cell.

To configure the data on the NodeB, perform the following steps:

1) Use the ADD SEC command to add a sector on the NodeB.2) Use the ADD LOCELL command to add a local cell on the NodeB.

IV. Examples

The following example is based on TX diversity in the downlink and 2-way RX diversity in the uplink.

To configure the data, perform the following steps:

1) Configure sectors on the NodeB.

TX diversity is applied in the downlink, 2-way RX diversity is applied in the uplink, and the receiving antennas are specified.

3) Configure local cells on the NodeB, and configure the resources of TX channels in main and diversity paths according to the TX diversity mode of the sector.

4) Quickly set up a cell on the RNC.5) Modify TX diversity parameters of the cell on the RNC.6) Activate the cell.

//Set up a local cell on the NodeB through the following command:


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ADD SEC: STN=0, SECN=1, SECT=LOCAL_SECTOR, ANTM=2, DIVM=TX_DIVERSITY,

ANT1SRN=3, ANT1N=N0A, ANT2SRN=3, ANT2N=N1A;

ADD LOCELL: LOCELL=0, STN=0, SECN=1, SECT=LOCAL_SECTOR,

BBPOOLTYPE=GEN_POOL, SRN1=2, SN1=0, SRN2=2, SN2=1, ULFREQ=9850,

DLFREQ=10800, HISPM=FALSE, MXPWR=430;

//Set up the cell on the RNC quickly, and modify its parameters after the cell is set up.

ADD QUICKCELLSETUP: CellId=110, CellName="cell110", BandInd=Band1,

UARFCNUplink=9850, UARFCNDownlink=10800, PScrambCode=110, TCell=CHIP256,

LAC=9479, SAC=1, CfgRacInd=REQUIRE, RAC=1, URANUM=D1, URA1=1,

NodeBName="3812E104", LoCell=0, SupBmc=FALSE;

MOD CELLSETUP: CellId=110, SupSSDT=TRUE, TxDiversityInd=TRUE,

DpchTxDiversityMode=STTD, HsPdschTxDiversityMode=STTD, CLTAModeInd=TRUE,

ClosedLoopTimeAdjustMode=OFFSET1;

ACT CELL: CellId=110;

V. Verify the Enabled Feature

Use the UE that supports TX diversity to send a service setup request message. Then check the diversity settings of related channels during the signaling procedure.

35.6.2 Reconfiguring TX/RX Diversity Parameters

To reconfigure the diversity settings of a cell, perform the following steps:

7) Deactivate the logical cell that is associated with the local cell on the NodeB that requires reconfiguration.

8) Use the MOD SEC command to modify the diversity settings of the sector.9) Use the MOD LOCELL command to modify the diversity settings of the local cell.10) Activate the logical cell.

35.6.3 Disabling TX/RX diversity

To change RX diversity mode to no RX diversity mode, set the Antenna Magnitude parameter to 1. For details, refer to step 2 in section 35.6.2 "Reconfiguring TX/RXDiversity Parameters".

To change TX diversity mode to no TX diversity mode, use the MOD CELLSETUP command to set the TX diversity ind parameter to FALSE on the RNC.

35.7 Maintenance Information

35.7.1 Alarms

None.


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35.7.2 Counters

None.

35.8 References 3GPP TS 25.211, “Physical channels and mapping of transport channels onto

physical channels (FDD), V6.7.0”. 3GPP TS 25.211, “Physical layer procedures (FDD), V6.9.0”.


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35 tx rx diversity

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