A method for multiple channel recovery in TDMA wireless communications systems

A single base repeater failure in time division multiple access (TDMA) wire less systems causes all active calls on this base repeater to be dropped. I n order to increase system end-to-end availability, a multiple channel reco very method for TDMA wireless systems is proposed in this paper. By applyin g the method, when a base repeater fails, the channels of active calls carr ied by the base repeater are replaced by working channels in the channel po ol 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 b ase repeaters, but also with the channel failure recovery in handoff proces ses, transient channel failures, and new call setup processes. To predict s ystem availability and performance, hierarchical stochastic reward net mode ls are developed for analyzing channel allocation, base repeater failure/re pair, and channel recovery. The results show that the recovery method can n early eliminate dropped calls when the traffic load is light, and can drama tically 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. (C) 2001 Elsevier Science B.V. All rights reserved.