Research On Location Management Strategy Of GPRS System In Railway

As the applications of GSM-R in China railway become much wider and wider, there is short of radio frequency resource. Circuit switch data service can't meet the larger demand of data transmission. GPRS network is based on GSM-R network, so there are similarites and differences between two kinds of network regarding with location management strategy. The procedure of GPRS location management concludes cell reselect, cell update and routing area update; location management area consists of cell, routing area and location area. The routing area is added into GPRS network compared with two-level management area in GSM-R network. Three mobility management states and two session management states are designed for MS and network, compared with idle mode and dedicated mode designed for GSM-R mobile station. Mobility management states conclude idle, ready and standby. Session management states conclude PDP active and PDP inactive. So the location management strategy in GPRS network becomes more complicated.The procedure of GPRS location management in idle, ready, standby and PDP active, PDP inactive mode is analyzed particularly in this paper. Compared with the former research which establishs maths model based on the mobility management states and session management states respectively, mobility management states and session management states are creatively combined in this paper, and the mode transtion model based on idle, ready PDP active, ready PDP inactive, standby PDP active, standby PDP inactive mode is established. The Stochastic Process theory is used as maths tool to quantitatively analyze the mode transtion model, also the impact of location management strategy for data transmission delay is scientifically analyzed. Parameters which control the management procedure are optimized afer analysis, and the security of railway transportation will be improved.The effects of GPRS network location management on GSM-R network location management is also studied in this papter. The problem of data lost in Qinghai-Tibet railway has been solved completely based on the location management strategy research. The railway transportation and production is secured.