Delay Analysis of Cooperative GBN-ARQ Protocol Joint MAC Contention

Cooperative communication exploits the antenna of the free node and constitutesvirtual MIMO (multiple-input multiple-output) system to cope with channel fadingand obtain diversity gain. Cooperative communication is the key technology for thenext-generation wireless mobile network and becomes a research hotspot in recentyears. In this paper, a wireless cooperative transmission system is taken as theresearch model. The main work of the paper is listed as follows:(1) We presented an overview of the principles and characteristics of cooperativediversity, automatic retransmission request protocol and cooperative MAC andinvestigated the research status of the cooperative communication system delay andcooperative MAC protocol as well. It is extracted that the delay brought about byMAC layer contention has non-ignorable influence on the entire cooperativecommunication system delay. It is of great practical significance to study on the effectof the DCF access channel delay of MAC layer on the automatic retransmissionrequest protocol delay performance of data link layer in cooperative communicationnetwork.(2) A Markov-based queuing model is proposed, which joints cooperative MAC,GBN-ARQ automatic retransmission request protocol and adaptive modulation andcoding technology. Based on the average DCF access channel delay, we analyze theGBN-ARQ protocol performance for cooperative transmission network andinvestigate the packet queuing delay at the source node. The packet queuing problemof the source node is modeled as a GI/M/1Markov chain and the accurate queuinglength and delay probability distribution are obtained according to the theory ofmatrix geometric. The packet queuing delay probability distributions in the sourcenode of the cooperative link under different cooperative link quality constraints arecompared with the queuing delay distribution in direct link respectively.(3) Based on the decode-and-forward cooperative transmission network modelwhich combines the adaptive modulation and coding technique in the physical layerand GBN-ARQ automatic retransmission request protocol in data link layer, therandomly changed feedback delay incurred by collision resolution in MAC layer istaking into consideration and the data packet queuing delay at the source node isfurther analyzed and quantized. According to the IEEE802.11DCF backoff mechanism, the collision resolution period caused by the contention among the sourcenodes for the helper is analyzed and the feedback delay transition probability matrixfor the channel reservation of the source is deduced. A Markov-based delay queuingmodel is constructed for packets transmission in the cooperative network where thesource employs link adaption technique. The process of the entire system stateevolution is discussed and then queuing theory and matrix geometric method areadopted to analyze the queuing model. The much more accurate queuing delayprobability distribution of the data packets at the source is achieved at last.The packet queuing delay results for the cooperative transmission networkobtained in this paper can play an important role in improving the network delayperformance. Also, the accurate delay statistics could contribute to a better control ofthe packet traffic at the source node and to improve the throughput of the entirenetwork system.