MAXIMUM DATA THROUGHPUT OVER DIGITAL TRANSMISSION SYSTEMS.

Data carried over digital transmission facilities is characterized by errors which occur in occasional bursts. Most data communication equipment uses some form of block transmission with automatic repeat request (ARQ) protocol. In these systems, the maximum throughput (error-free data rate) which can be obtained depends both on the statistics of the channel and on the chosen block lengths. In this paper, a simple Markov process is used as a model for digital transmission systems and its predicted results compared with measured data. The implications of the model are then discussed in terms of the optimum block length required for both start-stop and continuous automatic repeat request systems to maximize the data throughput that can be achieved over these channels. It is shown that longer block lengths are appropriate for these channels than for channels with independent bit errors at the same bit error rate.