Efficient ARQ error control strategies with adaptive packet length for mobile radio networks

The throughput of conventional ARQ protocols, such as the stop-and-wait, go-back-N and selective-repeat, can be improved by dynamically adapting the protocol packet length with the changes in channel conditions. Such an action requires a method for sensing the channel state and detecting a change in it. This paper examines four simple algorithms to implement such an adaptive system in a slowly varying mobile radio channel. It is shown that these algorithms performs remarkably well in spite of their simplicity. In particular, the algorithm based on counting the contiguous positive and/or negative acknowledgment messages provides a reliable channel state information (CSI) within only a few block transmissions, and requires the shortest observation interval among the four schemes.