Delay Outage Probability in Block Fading Channel and Relay-Assisted Hybrid-ARQ Network

In this letter, we focus on the delay outage probability in block fading channels and relay-assisted decode-and-forward hybrid-automatic retransmission request (HARQ-I) based systems. The delay outage is defined as the probability that the requirement on the average delay in additive white Gaussian noise (AWGN), could not be sustained in block fading channels. In other words, the system is said to be in outage if the mean delay exceeds a certain threshold θ_m due to the retransmission mechanism of erroneous packets. Our contribution lies in two folds: A closed form expression of the end-to-end delay in relay-assisted HARQ scheme is derived. Using the derived delay expression, an analytical form of the delay outage probability is proposed which might be very useful to avoid lengthy simulations.