Research Of IEEE 802.11 DCF Protocol Backoff Algorithm

Spectrum resources are becoming increasingly scarce.How to effectively share channel resources has become one of the hotspots in current research.This paper studies the impact of packet size on transmission probability,throughput,and media access latency under two access modes of the IEEE 802.11 DCF protocol.According to the amount of network load,the size of the minimum contention window(MCW)is improved,the contention window value under the condition of the minimum collision probability is obtained,and the throughput is improved.Firstly,two access modes of IEEE 802.11 DCF are studied(basic access mode and RTS/CTS access mode).For the large network overhead of the RTS/CTS access mode,the Bianchi model was introduced and the transmission probability formula and throughput formula were derived.The influence of packet length on the transmission probability and throughput is studied.The appropriate access mode is selected for different services and verified by experimental simulation.Secondly,the influence of the packet length on the access delay is studied under IEEE 802.11 DCF.Setting the threshold according to the length of the data packet,selecting the appropriate access mode,and is verified through experimental simulation.Then,the binary exponent backoff algorithm is improved,the backoff time order is modified,the number of retransmissions is increased,the throughput performance is improved,and verification is performed through experimental simulation.Finally,aiming to reduce the collision probability of existing backoff algorithm and improve the system throughput,the Bianchi model is reduced dimensionally,and the backoff algorithm based on the MCW value is improved.According to the network load,the minimum collision probability is obtained.The value of the MCW increases the throughput and is verified by experimental simulation.