CTH16-6: Adaptive Coding and Modulation for Hybrid ARQ Systems over Partially Observable Nakagami-m Fading Channels

We study coding and modulation rate adaptation problem for HARQ systems with partially observable state from cross-layer viewpoint. The rate of convolutionally coded M-QAM is adapted jointly with buffer state and channel state. We assume that perfect channel state information is not known at the transmitter, but it can be estimated from previous actions and observations. POMDP-based approach is utilized to formulate the problem, where average throughput is maximized, and average delay, packet error rate and overflows are minimized. To solve the cross-layer adaptation problem approximately, we discuss two heuristic-based methods and compare their applicability with completely observable channel state case by simulation results.