RED Theory for QoS Provisioning in Wireless Communications

In this paper, we study the performance limit of a wireless communication system over a fading channel. The system under study consists of 1) a finite-buffer discrete-time queueing system on the link layer, and 2) a rate-adaptive channel coding system on the physical layer. The objective of this paper is to analyze the relationship among data rate (R), packet error probability (E), and delay bound (D), under the interaction between the link layer and the physical layer. In our analysis, we consider three types of packet errors, i.e., 1) packet drop due to full buffer, 2) packet drop due to delay bound violation, and 3) packet decoding error due to channel noise. We obtain an upper bound on the packet error probability. Furthermore, by minimizing the packet error probability over the transmission rate, we obtain an optimal rate control policy that guarantees the user-specified data rate and delay bound. In the case of constant arrival, the optimal rate control policy results in an RED triplet; then by varying data rate and delay bound, we obtain RED Pareto-optimal surface, which serves as the performance limit of the system under study.