Huawei PBT Feature

PBT Feature Parameter Description Copyright © Huawei Technologies Co., Ltd. 2010. 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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BSS PBT

Contents

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

2 Overview of PBT .......................................................................................................................2-1 3 Technical Description ..............................................................................................................3-1 3.1 PBT ............................................................................................................................................... 3-1 3.2 Dynamic PBT ................................................................................................................................ 3-1

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

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BSS PBT

1 Introduction

1 Introduction 1.1 Scope This document describes the Power Boost Technology (PBT) feature and the dynamic PBT feature.

1.2 Intended Audience This document is intended for: z

Personnel who need to understand PBT

z

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: z

Feature change: refers to the change in the PBT feature of a specific product version.

z

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: z

02 (2009-09-30)

z

01 (2009-06-30)

02 (2009-09-30) This is the second commercial release of GBSS9.0. Compared with issue 01 (2009-06-30), issue 02 (2009-09-30) incorporates the changes described in the following table. Change Type

Change Description

Parameter Change

Feature change

None.

None.

Editorial change

The structure of the document is optimized.

None.

01 (2009-06-30) This is the first commercial release of GBSS9.0. Compared with issue 01 (2009-04-30) of GBSS8.1, issue 01 (2009-06-30) of GBSS9.0 has no change.

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BSSBSS PBTPBT

2 Overview of PBT

2 Overview of PBT In GSM networks with wide coverage, the improvement of uplink and downlink transmit power is of great importance. The PBT is a power boost technology. In PBT mode, the two TRXs in the double-transceiver unit are used as one TRX. After modulation and DA conversion, one signal output is divided into two RF signals. These two signals are amplified and then combined to form one signal. As the two signals are aligned in phase, the transmit power is amplified and the downlink signal strength is increased. In dynamic PBT mode, the timeslots corresponding to the two TRXs of a double-transceiver unit are set to PBT mode, and other timeslots are set to non-PBT mode. After the timeslots in PBT mode are released, they can be set to non-PBT mode. Dynamic PBT makes full use of idle timeslots and improves the signal strength in areas with weak coverage, such as at cell edges, indoors, or in cars. Based on actual network conditions, adjustments can be made to maintain the balance between capacity and coverage. Dynamic PBT is mainly applicable to concentric cells. In a concentric cell, when the downlink coverage in the overlaid subcell is restricted, continuous coverage is impossible. In this case, the TRX utilization is low if PBT is adopted.

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3 Technical Description

3 Technical Description 3.1 PBT In PBT mode, one signal is divided into two signals. The two signals are amplified and then combined to form one signal. After that, the two signals are superposed in the same phase and with the same frequency. Thus, the transmit power is almost doubled. Figure 3-1 shows the working principle of PBT. Figure 3-1 Working principle of PBT

TX1 Control Unit

TX TRX0

TX TX2

TRX1

The signal from TRX0 is divided into two signals by a divider. Then, the two signals enter RF units TX1 and TX2 respectively. After being amplified by the RF units, the two signals are combined by the combiner. Then, the combined RF signal is transmitted through the TX1 port. When PBT is enabled, the uplink coverage may be insufficient if the uplink signals are not amplified or the uplink receiver sensitivity is not improved. This may lead to imbalance between the uplink coverage and the downlink coverage. Thus, one of the following measures should be taken to improve the receive quality of uplink signals. z

Configuring Four-Way Receive Diversity

z

Configuring a tower mounted amplifier (TMA)

The TMA is a low-noise amplifier module that is mounted on a tower. After receiving uplink signals from the antenna, the TMA amplifies the signals and then transmits them to the feeder. Thus, the receiver sensitivity of the BTS is improved and the UL coverage is expanded. In addition, when the TMA is used, the transmit power of an MS is reduced and the speech quality is improved.

3.2 Dynamic PBT Dynamic PBT is timeslot-based. Normally, two TRXs in a double-transceiver unit work independently. If required, the two channels of the same timeslot number on the two TRXs work as a channel group. That is, the two channels can be converted into a channel group, and the channel group into two independent channels. This balances cost, capacity, and coverage. Dynamic PBT increases resource utilization and assists in expanding the coverage.

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BSS PBT

3 Technical Description

When the double-transceiver unit works in dynamic PBT mode, the channels with the same timeslot number on the two TRXs of the same double-transceiver unit form a PBT channel group. The two channels must be TCHs (TCHF or TCHH). The channel with a smaller TRX number is the primary channel, and the other channel is the secondary channel. The primary channel and the secondary channel are the channels with the same timeslot number on one double-transceiver unit. BCCHs, SDCCHs, PDCHs, and CBCHs cannot form a channel group. They can only be used as independent channels.

During channel assignment, the BSC searches for the optimal channels. After dynamic PBT is enabled, the BSC determines whether the optimal channels can form a PBT channel group if the PBT channel group should be assigned. If a PBT channel group can be formed, the BSC blocks the secondary channel. Then, the BSC assigns the channel group to the call. If the optimal channels cannot form a channel group, the BSC regards the channels as independent channels. If the optimal channels can form a channel group but one of them is occupied by a call, the BSC attempts to hand over the call to another channel. After the channel turns idle, a channel group is formed and then assigned to the call. In dynamic PBT mode, the downlink-limited handover decision algorithm is added to determine whether the downlink signal strength is limited. If the downlink signal strength is limited and the serving cell supports dynamic PBT, the call is handed over to an available channel group. If one of the two channels with the same timeslot number on one double-transceiver unit is occupied by the call, the call on the other channel should be handed over to another idle channel. When the downlink signal strength is increased to a certain level, the PBT channel group is not required. The BSC divides the channel group into two independent channels and maintains the call on the primary channel. At the same time, the BSC releases the secondary channel to increase the capacity of the cell. After dynamic PBT is enabled, the BSC reserves most possible channel pairs that can form channel groups during the assignment of normal independent channels.

With dynamic PBT used in the overlaid subcell, the coverage of the overlaid subcell is expanded through the handover of calls in the vicinity of the edge to the overlaid subcell. This helps to balance the traffic in the overlaid subcell and that in the underlaid subcell and also increase the success rate of handover from the underlaid subcell to the overlaid subcell. Dynamic PBT is a software solution. That is, the hardware connections of the BTS in dynamic PBT are the same as those in PBT, and only the software needs to be upgraded.

3-2


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4 Parameters

4 Parameters This chapter describes the parameters related to PBT. For the meaning of each parameter, see Table 4-1. For the default value, value ranges, and MML commands of each parameter, see Table 4-2. Table 4-1 Parameter description (1) Parameter

Description

Send Mode

RF transmission mode of the TRX

Table 4-2 Parameter description (2) Param eter

Send Mode

Default Value

None

GUI Value Range

Actual Value Range

NOCO MB(No Combin ation), PBT(PB T), WBAND COMB( Wideba nd Combin ation), DIVERS ITY(Tra nsmit Diversit y), DDIVER SITY(Dy namic Transmi t Diversit y), DPBT(D PBT), DTIC(Tr ansmit Indepen dency or Combin ation), NONE(n one)

NOCOMB, PBT, WBANDCO MB, DIVERSITY, DDIVERSIT Y, DPBT, DTIC, NONE

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Unit

None

MML Comma nd

SET GTRXDE V(Option al)

Impact

TRX


4-1

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5 Counters

5 Counters None.

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6 Glossary

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

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BSSBSS PBTPBT

7 Reference Documents

7 Reference Documents z

BSC6900 Feature List

z

BSC6900 Optional Feature Description

z

GBSS Reconfiguration Guide

z

BSC6900 GSM Parameter Reference

z

BSC6900 GSM MML Command Reference

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Huawei PBT Feature

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