Delay statistics for selective repeat ARQ protocol in multi-rate wireless networks with non-instantaneous feedback

We analyze the delay statistics for the selective repeat ARQ (SR-ARQ) protocol in a multi-rate wireless network with non-instantaneous feedback. Multi-rate transmission is assumed to be achieved through adaptive modulation, where each transmission mode corresponds to one state of a finite state Markov channel (FSMC) model. The problem is formulated as a quasi-birth and death (QBD) process from which the exact delay statistics for the SR-ARQ protocol is obtained. Our model removes the weaknesses of using a two-state Markov channel such as its inaccuracy in predicting the delay performance for a wireless access, error control protocol and its inability to capture multi-rate transmission. We validate the analysis by simulations and present typical numerical results, which reveal the impacts of the channel and the system parameters on the performance of a multi-rate wireless network