A channel recovery method in TDMA wireless systems

A single base repeater failure in TDMA wireless systems causes all active calls on this base repeater to be dropped. In order to increase the system end-to-end availability, an RF channel recovery method for TDMA wireless systems is proposed in this paper. By applying the method, when a base repeater fails, the channels of active calls carried by the base repeater are replaced by working channels in the channel pool of the base site. All the active calls continue without the intervention of end users. The method deals not only with the failure and recovery of base repeaters, but also with the channel failure recovery in handoff processes, transient channel failures, and new call setup processes. To predict system availability and performance, hierarchical stochastic reward net (SRN) models are developed for analyzing channel allocation, base repeater failure/repair, and channel recovery. The results show that the recovery method can nearly eliminate dropped calls when the traffic load is light, and can dramatically reduce dropped calls when the traffic load is normal. The price we pay is a slightly increased blocking probability, nearly transparent to the end users.