A Selective ARQ Protocol with a Finite-Length Buffer

Automatic repeat request (ARQ) techniques with error-detecting codes are commonly used in communication systems. Of these, selective protocols, while the most efficient, have the notable drawback of requiring large buffers at the receiver side. A new selective ARQ protocol with a finite-length buffer is described in this paper. If N is the number of codewords transmittable in the round-trip delay, the described protocol requires a buffer having length equal to N + N(a), + N(a) greater-than-or-equal-to 2 being an integer. A lower bound on the throughput of the described ARQ protocol is derived. The proposed protocol achieves higher throughputs than similar schemes, giving comparable results to selective protocols with infinite-length buffers for high error rates in the communication channel.