Markov analysis of video transmission based on differential encoded HARQ

In this paper, we analyze hybrid automatic repeat request applied to the transmission of video content over the wireless channel. Retransmission-based techniques are usually applied to queueing systems assuming a homogeneous flow of identical packets, which are all transmitted and possibly retransmitted in the same way. However, multimedia packets are encoded with incremental methods leveraging spatial and temporal redundancy and as such, they have different roles and should be treated differently by the retransmission mechanism. Therefore, our work considers a selective retransmission scheme with unequal error protection applied to a multimedia flow subdivided into distinguishable packets. We assume a binary channel with memory and non-zero round-trip time. We utilize discrete-time Markov chains to model the channel and the transmission/retransmission system. This enables a closed-form derivation of performance metrics via Markov analysis. Numerical results are discussed and possible implications on multimedia communications are evaluated.