Radio Common Channel Management

Radio Common Channel Management Feature Parameter Description

Copyright Huawei Technologies Co., Ltd. 2010. All rights reserved.

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BSS Radio Common Channel Management Contents

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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 Radio Common Channel Management .......................................................2-1 2.1 Channel Request by MS ............................................................................................................... 2-1 2.2 Paging ........................................................................................................................................... 2-1 2.3 Delete Indication............................................................................................................................ 2-2 2.4 CCCH Load Indication .................................................................................................................. 2-2 2.5 Broadcast Information Modify ....................................................................................................... 2-3 2.6 Short Message Cell Broadcast...................................................................................................... 2-3 2.7 Immediate Assignment.................................................................................................................. 2-3 2.8 Notification..................................................................................................................................... 2-4

3 Engineering Guidelines............................................................................ 4 Parameters .................................................................................................................................3-1

5 Counters......................................................................................................................................4-1

6 Glossary ......................................................................................................................................5-1

7 Reference Documents .............................................................................................................6-1

BSS Radio Common Channel Management 1 Introduction


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1 Introduction 1.1 Scope This document describes signaling procedures, such as channel request by MS and assignment. It also describes common channel management.

1.2 Intended Audience This document is intended for:

z Personnel who need to understand Radio Common Channel Management 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 Radio Common Channel Management 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 (2010-07-15) z 01 (2010-01-20)

02 (2010-7-15) This is the second issue of GBSS9.0.

Compared with issue 01(2010-01-20) of GBSS9.0, issue 02 (2010-07-15) of GBSS9.0 incorporates the changes described in the following table.

Change Type Change Description Parameter Change

Feature change

Multiple CCCHs is added. None.

Editorial change

None. None.

01 (2010-01-20) This is the first issue.

BSS Radio Common Channel Management

2 Overview of Radio Common Channel Management


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2 Overview of Radio Common Channel Management Radio common channel management involves the management of common control channels such as PCH, RACH, AGCH, NCH, PPCH, PRACH, and PAGCH. Radio common channel management is a basic feature for the operators to provide CS speech services.

z Common control channels Common control channels include PCH, RACH, AGCH, NCH, PPCH, PRACH, and PAGCH. Paging Channel (PCH): Downlink channel. The MS listens to the PCH at intervals to determine whether there is a call request from the MSC. Random Access Channel (RACH): Uplink channel: The MS accesses the network through the RACH and requests the network to assign an SDCCH. Access Grant Channel (AGCH): Downlink channel. The network informs the MS of the assigned dedicated channel (SDCCH or TCH) through the AGCH. Notification Channel (NCH): Downlink channel, used for voice group call service (VGCS) and voice broadcast service (VBS). Packet Paging Channel (PPCH): Downlink channel. The MS listens to the PPCH at intervals to determine whether there is a packet request from the SGSN. Packet Random Access Channel (PRACH): Uplink channel. The MS requests network access through the PRACH.

z Radio common channel management The radio common channel management procedures involve the signaling procedures of MS access and assignment, and also the resource management of the common channel. The involved procedures are Channel Request by MS, Paging, Delete Indication, CCCH Load Indication, Broadcast Information Modify, Short Message Cell Broadcast, Immediate Assignment, and Notification.

2.1 Channel Request by MS The procedure is initiated by a TRX upon detection of a random access from an MS (CHANNEL REQUEST message from MS). The TRX then sends a CHANNEL REQUIRED message to the BSC containing the Request Reference parameter (random number selected by the MS plus some low order bits of the TDMA frame number for the access) and the measured delay of the Access Burst.

The number of access conflicts on RACHs during MS access can be reduced by adjusting the values of TX-integer and MS MAX Retrans, thus increasing the RACH utilization.

2.2 Paging This procedure is used to request the paging of one mobile station on a given paging subchannel.

The paging of an MS is initiated by the BSC sending a PAGING COMMAND message to the BTS. The message contains the MS identity (TMSI or IMSI), the paging population number of the MS, optionally an indication for the MS about which combination of channels will be needed for the subsequent transaction related to the paging and optionally an indication of the eMLPP priority of the call.

The PAGING REQUEST messages to be sent on the radio path are built and sent by the BTS.


BSSRadio Common Channel Management

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The parameter BS_AG_BLKS_RES determines the CCCH usage for the AGCH and the PCH and thus affects the system performance and the paging response time of MSs. The parameter BS_PA_MFRMS determines the paging response delay and the MS power consumption. The paging success rate can be improved by setting Paging Times to a proper value.

Of these logical channels, the PCH, AGCH, NCH, and RACH are called CCCHs.

In common cases, one cell is configured with one BCCH physical channel, which is configured on timeslot 0 of the BCCH TRX. The feature of Multiple CCCHs (GBFD-511501 Multiple CCCHs) also allows one to configure timeslots 2, 4, and 6 of the BCCH TRX as BCCH physical channels. These BCCH physical channels can be divided into the BCCH, PCH, and AGCH in the downlink, and the RACH in the uplink. Messages sent on the BCCH logical channel are exactly the same no matter they are sent on timeslots 0, 2, 4, or 6. Messages sent on the PCH, AGCH, and RACH, however, can be different on timeslots 0, 2, 4, and 6. Thus, more messages can be sent on the PCH, AGCH, and RACH, and configuring multiple BCCH physical channels expands the CCCH capacity.

The BSC broadcasts the configured number of CCCHs to the MS in system information type 3 messages. The MS determines on which timeslot to monitor the paging message based on its IMSI.

Uplink BCCH physical channels are all RACHs, so configuration of multiple CCCHs increases the number of RACHs in the cell. Thus, Multiple CCCHs also improves the random access capability of the cell.

2.3 Delete Indication This procedure is used by the BTS to indicate that due to overload on the downlink CCCH, an IMMEDIATE ASSIGN COMMAND has been deleted.

For that purpose , the BTS sends a DELETE INDICATION message to the BSC.

2.4 CCCH Load Indication This procedure is used by a BTS to inform the BSC of the load on a particular CCCH timeslot.

The CCCH LOAD INDICATION message is sent regularly from the BTS to the BSC if the load exceeds some value set by O&M. The sending rate is also set by O&M.

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2.5 Broadcast Information Modify This procedure is used by the BSC to indicate to the BTS the new information to be broadcast on BCCH.

For that purpose, the BSC sends a BCCH INFORMATION message to the BTS.

2.6 Short Message Cell Broadcast Short Message Service Cell Broadcast messages are sent to the BTS as SMS BROADCAST COMMAND messages.

With the SMS BROADCAST COMMAND mode of operation, the BSC can request the broadcast of a complete Cell Broadcast message. The BSC handles the queuing, repetition and transmission of the messages taking the capacity of the CBCHs (basic and extended channel [see 3GPP TS 45.002]) into account. The BSC is responsible for the segmentation of the SMS Cell Broadcast messages on the Radio interface:

2.7 Immediate Assignment This procedure is used by the BSC to request the transmission of an IMMEDIATE ASSIGN Message on downlink CCCH. To initiate the immediate assign, the BSC sends an IMMEDIATE ASSIGN COMMAND message. The message contains the complete immediate assign message as defined in 3GPP TS 44.018 (IMMEDIATE ASSIGNMENT or IMMEDIATE ASSIGNMENT REJECT) with the "Page Mode" element set to the value "no change".

The IMMEDIATE ASSIGNMENT REJECT message is either sent by the BTS as received in the IMMEDIATE ASSIGN COMMAND message or built by the BTS from the contents of two or more IMMEDIATE ASSIGN COMMAND messages. For the latter case the BTS may consider request references with identical contents within the same message as duplicates and all but one may be suppressed.


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2.8 Notification This procedure is used to request that notification be performed by the BTS. The BSC indicates the exact action required by the BTS in the command indicator.

The NOTIFICATION messages to be sent on the radio path are built and sent by the BTS.

The BSC manages the NCH DRX information whereas the BTS manages the scheduling of the messages on the NCH.

If the BTS for some reason cannot perform the notification commanded by the BSC, then the BTS should return an ERROR REPORT message with the relevant cause value.

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3 Parameters This chapter describes the parameters related to Radio Common Channel Management.

For the description of each parameter, see . For the default value, value ranges, and MML commands of each parameter, see .

Table 3-1Table 3-2

Table 3-1 Parameter description (1)

Parameter Description

RTTI PDCH Multiplex Threshold Maximum number of RTTI TBFs that can be multiplexed on the PDCH. A PDCH can be assigned when the number of RTTI TBFs on it is smaller than the value of this parameter. This parameter is valid only when its value is smaller than or equal to "MSRD PDCH DL Multiplexing Threshold".

3 Parameters BSS

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TX-integer Tx-integer (T for short). This parameter specifies the number of timeslots between two transmissions when an MS sends multiple consecutive channel requests. The access algorithm is defined in GSM Rec. 04.08 to reduce the collisions on the RACH and improve the efficiency of the RACH. The algorithm specifies three parameters: Tx-integer (T for short), maximum number of retransmissions (RET), and S related to channel combination. This parameter works with the configuration of the CCCH to determine the parameter S. The relations between this parameter and the configuration of the CCCH are as follows: When this parameter is set to 3, 8, 14, or 50, S is 55 if the CCCH and SDCCH do not share a physical channel. When this parameter is set to 3, 8, 14, or 50, S is 41 if the CCCH and SDCCH share a physical channel. When this parameter is set to 4, 9, or 6, S is 76 if the CCCH and SDCCH do not share a physical channel. When this parameter is set to 4, 9, or 6, S is 52 if the CCCH and SDCCH share a physical channel. When this parameter is set to 5, 10, or 20, S is 109 if the CCCH and SDCCH do not share a physical channel. When this parameter is set to 5, 10, or 20, S is 58 if the CCCH and SDCCH share a physical channel. When this parameter is set to 6, 11, or 25, S is 163 if the CCCH and SDCCH do not share a physical channel. When this parameter is set to 6, 11, or 25, S is 86 if the CCCH and SDCCH share a physical channel. When this parameter is set to 7, 12, or 32, S is 217 if the CCCH and SDCCH do not share a physical channel. When this parameter is set to 7, 12, or 32, S is 115 if the CCCH and SDCCH share a physical channel. The timeslot for sending messages is a random value from the collection of {0, 1..., MAX(T, 8)-1}. The number of timeslots (excluding the timeslot used to send messages) between two adjacent channel request messages is a random value from the collection of {S, S+1, ..., S+T-1}. When T increases, the interval between two adjacent channel requests increases, and RACH conflicts decrease. When S increases, the interval between two adjacent channel request messages increases, and RACH conflicts decrease, thus improving the usage of AGCH and SDCCH. The access time of the MS, however, is prolonged and the network performance is decreased when T and S increase. Under normal conditions, an appropriate T value should be used to ensure that S is as low as possible, and ensure that AGCH and SDCCH are not overloaded.



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MS MAX Retrans Maximum number of Channel Request messages that can be sent by an MS in an immediate assignment procedure. After the MS initiates the immediate assignment procedure, it always listens to the messages on the BCCH and all the common control channels (CCCHs) in the CCCH group to which the MS belongs. If the MS does not receive Immediate Assignment or Immediate Assignment Extend messages, it retransmits Channel Request messages at a specified interval. If the downlink quality is poor, the MS may send SABM frames to the BTS multiple times.

CCCH Blocks Reserved for AGCH

BS-AG-BLKS-RES, indicating the number of the CCCH message blocks reserved for the AGCH. After the CCCHs are configured, the value of this parameter indicates actually the seizure rates of the AGCHs and the PCHs over the CCCHs.

Multi-Frames in a Cycle on the Paging CH

Number of multiframes in a cycle on a paging sub-channel. In fact, this parameter specifies the number of paging sub-channels that a paging channel in a cell is divided into. In an actual network, an MS does not listen to other paging sub-channels but its belonging paging sub-channel only. Refer to GSM Rec. 05.02 and GSM Rec. 05.08. The larger the value of this parameter, the more the number of the paging sub-channels in a cell, and the fewer the number of the users belonging to each paging sub-channel. In this case, the mean uptime of the MS battery can be prolonged. Refer to the computing mode of paging group in GSM 05.02 of GSM Standards. The larger the value of this parameter, however, the larger the time delay of a paging message in a space segment. Thus, the average service performance of the system lowers. Based on the principle of ensuring that overload does not occur to paging channels, you must set this parameter to a value as small as possible. You must regularly measure the overload conditions of the paging channels in a running network and accordingly adjust the value of this parameter properly. A paging message in a location area must be sent in all the cells within this location area at the same time. Therefore, the capacity of a paging channel of each cell in a location area must be the same or nearly the same. The capacity refers to the calculated number of paging sub-channels of each cell.

Paging Times For the BTS, this parameter is used to determine paging retransmissions. This parameter and the number of paging times configured in the MSC determine the number of paging retransmissions. The total number of paging times is approximately equal to the value of this parameter multiplied by the number of paging times configured in the MSC.

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Table 3-2 Parameter description (2)

Parameter Default Value GUI Value Range

Actual Value Range

Unit MML Command

Imapct

RTTI PDCH Multiplex Threshold

3010~80 10~80 None SET GCELLPSCHM(Optional)

Cell

TX-integer TX_32 TX_3(3), TX_4(4), TX_5(5), TX_6(6), TX_7(7), TX_8(8), TX_9(9), TX_10(10), TX_11(11), TX_12(12), TX_14(14), TX_16(16), TX_20(20), TX_25(25), TX_32(32), TX_50(50)

TX_3, TX_4, TX_5, TX_6, TX_7, TX_8, TX_9, TX_10, TX_11, TX_12, TX_14, TX_16, TX_20, TX_25, TX_32, TX_50

None SET GCELLIDLEBASIC(Optional)

Cell

MS MAX Retrans 4_Times 1_Times(1_Times), 2_Times(2_Times), 4_Times(4_Times), 7_Times(7_Times)

1_Times, 2_Times, 4_Times, 7_Times

None SET GCELLCCBASIC(Optional)

Cell

CCCH Blocks Reserved for AGCH

10~7 0~7 None SET GCELLIDLEBASIC(Optional)

Cell



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Multi-Frames in a Cycle on the Paging CH

2_M_PERIOD 2_M_PERIOD(2 Multiframe Period), 3_M_PERIOD(3 Multiframe Period), 4_M_PERIOD(4 Multiframe Period), 5_M_PERIOD(5 Multiframe Period), 6_M_PERIOD(6 Multiframe Period), 7_M_PERIOD(7 Multiframe Period), 8_M_PERIOD(8 Multiframe Period), 9_M_PERIOD(9 Multiframe Period)

2_M_PERIOD, 3_M_PERIOD, 4_M_PERIOD, 5_M_PERIOD, 6_M_PERIOD, 7_M_PERIOD, 8_M_PERIOD, 9_M_PERIOD, step: multiframe period

ms SET GCELLIDLEBASIC(Optional)

Cell

Paging Times 41~8 1~8 None SET GCELLCCBASIC(Optional)

Cell

BSS Radio Common Channel Management 4 Counters


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4 Counters None

BSS Radio Common Channel Management 5 Glossary


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

BSS Radio Common Channel Management 6 Reference Documents


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6 Reference Documents z 3GPP TS 48.058 V7.0.0 z 3GPP TS 45.058 z 3GPP TS 44.018 z BSC6900 Feature List z BSC6900 Optional Feature Description z BSC6900 GSM Parameter Reference z BSC6900 GSM MML Command Reference

1 Introduction 1.1 Scope 1.2 Intended Audience 1.3 Change History 2 Overview of Radio Common Channel Management 2.1 Channel Request by MS 2.2 Paging 2.3 Delete Indication 2.4 CCCH Load Indication 2.5 Broadcast Information Modify 2.6 Short Message Cell Broadcast 2.7 Immediate Assignment 2.8 Notification

3 Parameters 4 Counters 5 Glossary 6 Reference Documents

Radio Common Channel Management

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