Hybrid TDMA/CSMA protocol for self managing packet radio networks

Abstract

This paper details work on a hybrid channel access protocol being undertaken at DRA Malvern. The protocol is based on both carrier sense multiple access and adaptive reservation time division multiple access channel access protocols. It is to be implemented on a packet radio demonstrator system currently employing a contention based CSMA protocol to access a single 25 kHz VHF channel. At high traffic loadings, system performance degrades due to an increase in clashes as more stations try to access the channel. The implementation of a protocol based on a time slot principle with the addition of carrier sensing within unused slots is shown to increase the channel efficiency under all traffic loading conditions and thus improve overall system performance.