The University of British Columbia

The performance implications of retransmission diversity packet combining on the RLC (radio link control)/MAC (medium access control) layer and transport layer protocol performance are investigated for three different heuristic-based RLC/MAC layer access control schemes in a CDMA S-ALOHA network under frequency selective Rayleigh fading. The transport layer protocol implements a two-level error recovery mechanism for reliable data transmission. Two different transport layer timer control mechanisms are considered. Implications of some physical layer parameters on system performance are discussed. It is observed that, for two-level error recovery through a reliable transport protocol, the achieved throughput depends on the transport protocol timer control mechanism and a suitable mechanism can be identified for an underlying RLC/MAC layer access control scheme and a particular physical layer design