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

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.