Abstract
In this paper, we critically compare the performances of bulk, per-subcarrier and combined selection schemes in super dense networks. Specifically, their outage and contention probabilities are critically appraised. To analyze the effects of outage and contention together, a performance parameter termed the bulk gain factor is defined and employed. Finally, we find that although the bulk selection scheme yields a worse outage performance, it would still be preferable in super dense networks as long as a sufficiently large transmit power is employed, since it only demands one relay and has a lower contention probability. Note, this conclusion is constructed based on the fact that when the bulk selection scheme is applied, the contention probability is still much higher than the outage probability in super dense networks. Our results serve as a design benchmark for physical layer applications/protocols used in super dense networks. Also, with these results, we provide a theoretical basis to further optimize super dense networks by reducing contention probability.