Throughput gains with limited feedback in cooperative relay networks

In this work, we consider delay-constrained systems in cooperative relay networks, and derive methods to maximize the throughput when a limited feedback link to the transmitter nodes exist. We derive the optimal rate control policy, and show that with just a few bits of feedback, most of the gains of the perfect feedback rate control policy are achievable. We maximize the throughput for popular methods of transmission in a network such as relaying, routing, and direct transmission. It is observed that for a finite rate of feedback, the throughput maximizing outage probability can be relatively high. This suggests using higher rate codes, and allowing some outages in an effort to increase the overall throughput. Interestingly, for large average power constraints, power control is unnecessary to maximize the throughput. On the other hand, for small average power constraints, we show that power control is more important than rate control.