Opportunistic feedback protocol for minimizing power in uplink with heterogeneous traffic

This paper considers a wireless uplink, where some users have deadline-sensitive (DS) traffic and others have best-effort (BE) traffic. The objective is to meet the deadlines for DS packets a fixed percent of time (QoS guarantee), at the same time minimizing the sum-power used for transmission in a distributed manner without feedback from all users to the base station (BS). Given each user's channel state and rate requirement, the optimal user ordering that minimizes sum-power is shown to be independent of the rate requirements and depends solely on the channel conditions. Based on this, using a limited amount of feedback, the proposed opportunistic feedback (OF) protocol guarantees QoS to DS data and minimizes sum-power. Numerical results show that (i) the OF protocol provides deadline-meeting guarantees and (ii) minimizes sum-power with a greatly reduced feedback overhead as compared to that of a central scheduler.