Research On Channel Allocation In GSM-R System

In the lack-of-wireless-resource circumstance that there is only 4MHz frequency width available to the GMS-R, the problems about how to ensure the quality of large, two-way messaging between the train and the gound control center, in particular, ensure the quality of communication of train control commands and the handoff calls, are increasingly urgent to solve. And to seek a method of channel allocation , witch is reasonable and effective , is the key to solve these existing problems.First of all, this thesis studies two prioritized handoff methods in GSM system: the first one is the dynamic channel allocation with guard channel and handoff queuing; the second one is the PRI-based channel allocation. The simulated analysis targeting the blocking rate of the two above-mentioned methods indicates that the application of both methods can help reduce the blocking rate and improve the capacity of the system, but the demand of QoS in the railway GSM-R cannot be measured up to. Secondly, taken the characteristics of wireless coverage along the railway line and the reality of railway transportation into consideration, the author is going to put forth a channel allocation strategy which combines HQ and GC with eMLPP. The strategy firstly ensures the reliable transmission of the numbers of train control, and then primordially considers a handoff to meet the requirement of GSM-R system. That is to say, a certain number of communication channels could be especially reserved for the handoff calls. Meanwhile the rate of successfully establishing connection with the users of high priority could be enhanced. Finally, a software-based and simulated performance evaluation is carried out to test whether the channel allocation strategy in this thesis can meet the requirements of GSM-R QoS.To sum up, this thesis, through analyzing all indexes of the simulated results, has identified that the communication channel method can meet the QoS demands of the GSM-R system. The expected results of certain referencing value to the communication channel allocation of the GSM-R have been achieved...