Analysis and optimization of an adaptive go-back-N ARQ protocol for time-varying channels

This paper outlines a systematic and efficient method to concurrently optimize a multiplicity of design variables for an adaptive go-back-N ARQ strategy both in noiseless and noisy feedback channels. For this continuous ARQ protocol, we adapt the number of identical message blocks sent in each transmission dynamically to the estimated channel condition. The channel state information is obtained by counting the contiguous ACK and NACK messages. Exploiting the asymptotic properties of the steady-state probability expressions, we show analytically that the optimum solution indeed lies in the infinite space. Subsequently, a simple method to estimate the suboptimal design parameters is suggested. Our approach of minimizing the mean square error (MSE) function also yields to a quantitative study of the appropriateness of the selected parameters. The results provide fundamental insights into how these key parameters interact and determine the system performance