Analysis of a Delay-Constrained Hybrid ARQ Wireless System

A real-time wireless system using hybrid automatic repeat request to correct errors is analyzed. Packet errors are modeled by a two-state Markov chain, and batch packet arrivals are allowed. Packets are dropped at the sender if their delays exceed a time limit, possibly after a number of retransmissions. Using the delay-model approach, a closed-form expression of packet-loss probability (PLP) and an approximate formula of wireless effective bandwidth (WEB) satisfying the quality of service requirements have been derived. If Bose–Chaudhuri–Hocquengem codes are used, an expression estimating the number of correctable bits to minimize the PLP has also been obtained. Moreover, the WEB is found to be independent of the packet size, and the PLP decreases exponentially as the WEB increases.