Gsm bss network kpi (sdcch congestion Rate) Optimization Manual

3Optimazation Method of SDCCH Congestion

3.1Analysis Procedure of SDCCH Congestion Rate

SDCCH congestion rate is classified into BSC-level and cell-level according to the statistic object of the counter. The SDCCH congestion rate of a BSC is composed of the SDCCH congestion rate of a series of cells.
Compared with the SDCCH congestion rate of the competitors, the Huawei SDCCH congestion rate cannot exclude the congestion in the handover procedure. Few networks are enabled with the function of SDCCH handover; therefore, the formula of SDCCH congestion rate of Huawei is almost the same as that of the competitors.

Procedure of SDCCH congestion rate analysis

Figure 2 Procedure of SDCCH congestion rate analyses
First, determine the level of the SDCCH congestion rate. If the congestion occurs in a large area, check the traffic volume and the setting of T3212. Then, calculate the SDCCH capacity to check whether it meets the system demand and whether the faults exist on system-level equipment or transmission. If congestion occurs in only a few cells, check the hardware, data configuration, and Um interface quality of the cell.

3.2Optimazation Method of SDCCH Congestion Rate

3.2.1Checking Hardware

Faults on the TRX, BTS, and transmission may cause SDCCH congestion.
To see whether there are faults on the hardware, query the alarms of transmission, board communication, CDU VSWR, and clock. In addition, query transmission-related traffic counters such as the CRC frames received by the BTS on the LAPD link in the LAPD performance measurement.

3.2.2Checking Channel Configuration

Query the traffic statistics to see whether the traffic volume on the SDCCH and TCH are higher than the normal value. If the congestion is caused by excessive traffic on the SDCCH, for multi-TRX BTSs, enable SDCCH dynamic allocation function or increase the number of SDCCH channels to relieve the congestion. For cells with only one TRX or without extra channels, enable the very early immediate assignment procedure. In the very early immediate assignment procedure, the TCH channel is immediately assigned when the SDCCH has no available resource during the processing of access request. In this case, a TCH can be used as only one SDCCH, which is a waste of the TCH resources. For the method of computing the capacity, refer to the Guide to Capacity Planning.
Some counters related to the BSC6000 are listed in the following table.