Energy efficient OFDMA: Trade-off between computation and transmission energy

We study minimization of overall energy consumption of OFDMA systems, which are widely adopted in future wireless communications. Based on the existing resource allocation to minimize transmission energy, the computation energy increases due to the complexity of allocating algorithms. Since high performance algorithms usually have high complexity, there exist trade-offs between transmission energy and computation energy. To systematically minimize overall energy consumption comprised of transmission and computation, we propose to minimize transmission energy by resource allocation while keeping the computation energy low via reduced-complexity algorithm. We further extend this idea to relay since it is well known to reduce transmission energy but only a few of works to minimize total energy consumption. In our numerical results, we demonstrate that in the scenario without relay, our algorithm can achieve near-minimum transmission energy (80% savings) under quite computation energy. In the scenario with relay, our algorithm can do even better by saving more transmission energy (88% savings) under a minor increase of computation energy. Both scenarios suggest that the global energy minimum can be achieved by proper trade-off between communication and computation energy consumption.