Recouping opportunistic gain in dense base station layouts through energy-aware user cooperation

To meet the increasing demand for wireless capacity, future networks are likely to consist of dense layouts of small cells. Thus, the number of concurrent users served by each base station (BS) is likely to be small which results in diminished gains from opportunistic scheduling, particularly under dynamic traffic loads. We propose user-initiated BS-transparent traffic spreading that leverages user-to-user communication to increase BS scheduling flexibility. The proposed scheme is able to increase opportunistic gains and improve user performance. For a specified tradeoff between performance and power expenditure, we characterize the optimal policy by modeling the system as a Markov decision process and also present a heuristic algorithm that yields significant performance gains. Our simulations show that, in the performance-centric case, average file transfer delays are lowered by up to 20% even in homogeneous scenarios, and up to 50% with heterogeneous users. Further, we show that the bulk of the performance improvement can be achieved with a small increase in power expenditure, e.g., in an energy-sensitive case, up to 78% of the performance improvement can be typically achieved at only 20% of the power expenditure of the performance-centric case.