Throughput-Delay Tradeoff in Coupled Queues in Wireless Networks: Priority and Concurrent Transmissions Regimes

Abstract

This paper investigates the performance of a wireless network that consists of two pairs of transmitter-receiver sharing the same channel, modeled using two coupled queues. In this analysis, we use the power metric \mathscr P, defined as the ratio of throughput and mean delay, to understand the compromise between these two metrics. We show that, when the users' transmit power levels are adjusted to maximize \mathscr P, two transmission regimes emerge. When the coupling degree between the queues is strong, but the traffic is not heavy, there will be plenty of opportunities for non-concurrent transmissions. Our analysis shows that, in this case, the best strategy is to prioritize one user over the other through appropriate transmit powers adjustment and to use the highest modulation order available. On the other hand, for heavy traffic, none of the users should be prioritized, and there is an optimum combination of robust modulation orders and transmit power ratio to achieve the best performance.