Energy-Efficient Transmission Strategies for Delay Constrained Traffic With Limited Feedback

In this paper, we developed transmission strategies able to deliver a prescribed number of packets by a deadline T while minimizing transmission attempts. All the packets have a single common transmission deadline. The three systems analyzed here differ from each other on the way channel state information (CSI) is provided by the receiver. In the first system, the receiver sends back CSI only when packets fail; in the second system, the receiver provides CSI only if this minimizes a given cost function; and in the third system, feedback is sent whenever a given threshold condition is verified. The communication channel is modeled as a time-varying correlated fading channel, represented by a Markov chain. For the first two systems, the optimal schedules are obtained through dynamic programming (DP). The third scheduler is based on a heuristic strategy, whose performance is evaluated through numerical simulations, and compared with that of the two optimal schedulers obtained through DP. Results showed that the heuristic scheduler can reach performance similar to that of DP schedulers.