The Analysis On Transmitting End Delay Of Cooperative SR-ARQ Protocols With Random Feedback Delay

In wireless communication networks, transmission delay is an important parameter of the measure of the network performance, which affects the flow control of the transmitter directly. This paper is concerned with the transmitting end delay performance of Selective Repeat Automatic Retransmission Request (SR-ARQ) protocol in cooperative diversity network. The transmission delay calculation model is proposed respectively for fixed feedback delay and random feedback delay. And by building virtual multiply antenna array to transmit information, cooperative diversity technology becomes one of effective techniques to mitigate the effects of fading. As the significant error-control technology, SR-ARQ protocol has an important role in ensuring the quality of the transmission. In order to use the character of the time variability of the wireless channel and increase the spectrum efficiency, Adaptive modulation and coding (AMC) scheme is applied in cooperative diversity network at the physical layer, which is able to adaptively change the modulation and coding scheme and the transmission rate according to the real condition of the wireless channel.In this paper, a three-node Decode-and-Forward (AF) cooperative diversity network model is proposed. The main work is as follows:The wireless channel is assumed to be a Nakagami-m fading channel, two different Finite State Markov Channel (FSMC) model are built, one is for the Selection Combining (SC) scheme, the other is for the Maximal-ratio Combining (MRC) scheme.Basing on the queuing theory and the character of SR-ARQ protocol, the paper focus on analyzing the process of packet transmission, and presents an end-to-end queueing analysis model for SR-ARQ protocol under cooperative diversity network with fixed feedback delay.Basing on the front research, the paper considers that packet waits to transmit at relay in possible, and analyzes the reason of producing random feedback delay. Then, a Markov model is proposed, which can represent the state of the feedback delay. Feedback delay value changes between two different random variables. And a feedback signal arrival model is presented. At last, the paper establishes Markov model of system states while the feedback delay is random variable. The packet probability of stability and the delay statistics are obtained by using matrix geometric methods.As the need of processing huge data volume and the speed of calculation, the parallel computing is adopted in numerical calculation program. The transmitting end delay model is validated by simulation under random feedback delay. In this paper, the calculating process for the transmitting end delay reflects fully the random time-varying feedback delay, meanwhile the results are precise. The exact probability distribution of transmission delay help the transmitter control the packet flow and improve the network performance in cooperative diversity network.