Low-Latency FEC Design With Geometric Packet Arrival and Delayed Feedback

This letter investigates the forward error correction code (FEC) design for achieving low end-to-end (E2E) latency in a communication system with geometric packet arrival and delayed feedback. We first derive the bounds for the optimal tradeoff between the E2E latency and the channel utilization by considering the automatic repeat request (ARQ) scheme with instantaneous feedback and the blind coding with no feedback, respectively. Then, we propose a flexible code design strategy by modeling the problem as a partially-observable Markov decision process (POMDP). Various tradeoffs between the latency and channel utilization can be achieved by adjusting the weighting coefficient in the reward function of the POMDP. Simulation results show that the coding strategy obtained via solving the POMDP outperforms the benchmark schemes by achieving lower E2E latency.