Thursday, April 26, 2012


Value range: 0~2 (1 combined CCCH), 0~7 (others)
Unit:  Block
Content: It is also called Access Granted Blocks Reserved. It is the number of CCCH channel message blocks that are reserved for access granted channels(AGCH).
Recommendation: 2

As downlink CCCH includes both AGCH and PCH, it is necessary to set the number of blocks, among CCCH message blocks, which are reserved for AGCH. To let MS know such configuration information, the system information of each cell includes a configuration parameter, which is the number of access granted blocks reserved (BS_AG_BLKS_RES). After CCCH configuration complete, this parameter actually assigns the proportion of AGCH and PCH on CCCH. it affects the time of MS’s response to the paging.
The network operator can adjust this parameter to balance the traffic of AGCH and PCH by referring to the following principles:
1. Principle for BS_AG_BLKS_RES: make this parameter as small as possible without causing overload of AGCH, so as to increase the capability of paging and improve the system performance.
2. Generally it is recommended to select 1 (when CCCH_CONF is 001), 2 or 3 (when CCCH_CONF is one of other values) for BS_AG_BLKS_RES.
3. During operation, observe the statistics of AGCH overload and adjust BS_AG_BLKS_RES properly.
Note: In Huawei system, when AGCH has been occupied, PCH can be used to send the immediate assignment command if it is free. If AGCH blocks reserved is set as 0, then the immediate assignment would be sent only  when there is an idle CCCH downlink channel. Therefore, a fixed capacity reserved for AGCH is necessary.

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