Value range: 0~255
Unit: 6 minutes
Content: It is Periodic Location Update Timer. It defines the period length of location updating.
Recommendation: 30 (for urban area), 20 (for suburban area)
MS will make location update when detecting the change of location, besides, MS will make periodic location update controlled by parameter T3212. Once MS read T3212 from system info., it will store it in SIM card. When the time exceeds T3212 value, the location update process will be triggered. The shorter the period the better the performance, but it will bring more signaling load for system. On setting of this parameter, the processing capabilities of MSC and BSC should be considered, also the flows of A interface, Abis interface, Um interface as well as those of HLR and VLR. Generally larger value for continuous covered urban area while smaller in the suburb, countryside or the place with poor coverage.
Large T3212( 16 hours 20 hours) is recommended for the area with much traffic, and small T3212 (3 hours, 2 hours) for the area with a little traffic. For the area where the traffic exceeds the system capacity, it is recommended to set T3212 as 0 (no periodic location update). To set the value of T3212 properly, it’s necessary to conduct long-term measurement on the processing capability and flow of each entity in the system. If any overload occurs, increase the value T3212. Note that this value should be smaller than the period by which the network queries the IMSI attached subscriber. Otherwise, the following situation occurs: When MS has not done any operation in a certain time, and it is not yet the time for periodic location update, the network will set IMSI flag of MS as detach, because its query result shows that MS has not done any operation. Thus, the network will not process the paging of this MS. So, before MS initiates another round of periodic location update, once there is a call for the MS, the network will voice the calling subscriber that the called MS is out of service area or has been powered off. When MS reselects a different location area, MS will make a non-periodic location update and reset T3212 in the new cell. If it reselects in the same location area, then the timer value will be remainder of the original one divided by the new T3212.