Energy Efficient Causal Packet Scheduling in Wireless Fading Channels with Hard Delay Constraints

In this paper we study the problem of energy efficient packet scheduling in wireless fading channels with hard delay constraints. Each packet has a strict delay constraint of D time slots and it has to be delivered before its delay deadline. Optimal scheduling of each packet now depends on future Channel State Information (CSI) which is not available. We develop the upper and lower bounds on the optimal output rate and develop a two step solution. In the first step we solve the relaxed optimization problem without bounds by using Lagrange Optimization theory and obtain an initial output rate. In the second step this output rate is adjusted such that the deadlines are successfully achieved. Simulation results show good performance in terms of energy efficiency.