Class based Selective-ARQ scheme for high performance TCP and UDP over wireless links

Abstract- Applications and services for mobile devices can benefit substantially from the use of Automatic Repeat reQuest (ARQ) link layer protocols for wireless connections. However, a drawback comes with their use when transferring mixed traffic type, which is the introduction of excessive and highly jittered transmission delay, which negatively affect the performance of both real-time and TCP traffic. Here, we propose a selective ARQ protocol which is capable of switching between ARQ and non-ARQ modes based on two policies which we have defined. Our first policy is based on the assumption that for real-time traffic minimisation of delay is more important than reliable transmission. The second policy is an extension of the first and introduces a mechanism, which monitors the length of the buffer queue to decide whether or not packets should be sent with or without ARQ. Results obtained in this research show that real-time traffic can be sent with minimal delay jitter and within certain time boundaries, whilst TCP throughput can be increased significantly