Research On Wireless Channel Access Algorithm Based On Protocol Sequence

Protocol sequences are periodic and deterministic binary sequences with low Hamming cross-correlation.They have been used to define a deterministic medium access control protocol and can provide strict guarantee on worst-case throughout or delay performance to asynchronous users in wireless sensor networks or mobile ad-hoc networks without channel feedback by channel coding.However,traditional protocol sequences based schemes require that each user employs a fixed channel coding rate,and all sequence entries are mapped to slots with the same time duration.Such two limitations lead to unnecessary packet transmissions and a substantial amount of channel idle time,and thus bring a negative impact on the throughput and delay performance.To address this problem,this thesis proposes two protocol sequences based schemes as below.First,we propose a new protocol sequences based broadcast scheme,which allows each user to adjust its coding rate according to the information in every incoming packet.Through analytical and numerical results,we show that the proposed algorithm significantly outperforms other similar algorithms in terms of throughput or delay.Second,to support transmissions with unfixed packet length,we propose a new protocol sequences based scheme which allows each user to perform carrier sensing when a zero is read from the sequence.We derive the theoretical throughput and delay performance,and confirm the analysis via numerical study.It is shown that the new algorithm significantly improves the channel utilization compared with conventional protocol sequence based schemes,achieves the optimal capacity of p-persistent CSMA,and enjoys better delay performance than the optimal p-persistent CSMA.