Optimal and suboptimal scheduling over time varying flat fading channels

Abstract

This paper explores optimal and suboptimal packet schedulers for time-varying flat fading channels that trade-off between minimization of the average delay and the average transmitted power. Both uncorrelated and correlated block fading channels are investigated. Extending a previous work, we formulate the trade-off as a unconstrained Markov decision processes and find the stationary deterministic optimal policy using both relative value iteration and policy iteration algorithm. As well, we present constrained Markov decision processes formulation of the problem and linear programming algorithm to solve it and show that optimal schedulers are randomized in this case. In order to alleviate the computational complexity needed, to determine the optimal scheduling policy we propose a suboptimal log-scheduling policy that has performance close to that of the optimal scheduler. The proposed policy is also robust to different channel models. It is demonstrated that log-policy is favorable to the water-filling policy for very slow fading channels.