Energy-Efficient Communication via Feedback

We propose a feedback optimization framework to minimize the total energy consumption in point-to-point wireless communication links. The energy cost of both the forward link and the feedback link are taken into account. Given the energy consumption profile of both links, we minimize error probability subject to the total energy budget and a delay constraint. The proposed framework is based on a multi-phase feedback scheme in which a transmission, if decoded incorrectly, is followed by a retransmission with boosted energy. We use this framework to show that the gain of utilizing feedback is highly dependent on the energy consumption profile of the links and the total available energy. In particular, we identify scenarios in which the use of feedback significantly increases the energy efficiency, as well as scenarios where, surprisingly, the use of feedback is strictly suboptimal as compared to communication without feedback.