Study On Channel Allocation Model In GSM-R System

As one of the most transport tools, trains' development speeds have great effects on our country's economy. While the traditonal railway communication system can't meet the practical demands well. The GSM-R system was introduced into our country, a successful communication system which was widely used in European, in order to break through the restrainments.The GSM-R system can compromise railway communication and single network platform, so it cuts off the operation costs. Developing from GSM technology ensures its reliability. Based on the geographical features of the route along railway, the GSM-R still apply the channel allocation technique of the GSM system. It can't well satisfy the situation.This article analyse the tradional allocation model's feature, and taking the tradional allocation plan into marko state transfer diagram. Comparison between the two tradional channel using pattern's key factor , such as new call failure probability,the handoff failure probability and other key performances are also made. The new guiding channel tactics which set ratio between new calls and handoff calls are also be studied, and after comparing , the conclusion that the two above plan are also lack of thing about the trascation' s justice and priority was made.In this article, a fuzzy channel allocation model was made, the model contains a fuzzy channel processor,a resource estimator,a performance evaluator and base-station interface modules. This model can dynamically estimates available resources in macrocell and microcell, evaluate system's performance, and determine whether and how to allocate resources to a call, based on the call's required information, such as resource availability,mobility and other key factors. In the fuzzy channel allocator, we design a dynamic threshold to achieve uitilization balancing between macrocell and microcells in order to obtain higher channel utilization.Simulation results shows that this model can guarantee the performance of the exsisting calls and also get better system utilization.The application of fuzzy logic to GSM-R system not only enriches the theory of fuzzy logic control, but also offers a new method for channel allocation with high quality. Simulation results show that the application of fuzzy logic to GSM-R can get better performances than the tradional ways.