Power control and QoS trade-offs for real-time wireless traffic

Abstract

We study distributed power control for supporting real-time multimedia traffic over multiple access wireless links. The responsive nature of interference observed on wireless links coupled with the absence of a central co-ordinating entity makes distributed design a challenging problem. A trade-off between transmit power control and quality-of-service (QoS) arises naturally in such a setting. While transmitting at low power is "socially" beneficial in terms of reducing interference experienced by other links, it degrades the QoS experienced by the receiver. We capture this trade-off within a dynamic programming (DP) framework. We study the structural properties of the optimal power control policy under the assumption of unresponsive interference, and leverage the intuition thus gained to design power control policies for a responsive interference environment. We argue that the optimal policy has key fundamental differences compared to the classical Foschini-Miljanic type distributed power control. We demonstrate the efficacy of the proposed policies via simulation. We invoke the idea of inter-packet deadlines (IPD) to characterize real-time traffic, which leads to a tremendous reduction in the complexity of the state-space of the DP.

Distributed Backlog-Driven Power Control in Wireless Networking

“…2The choice of these functional forms was motivated by bit error rate (BER) formulae available froimn digital communication theory under different physical layer operating conditions [6] [l ]. is to minimize the expected sum of backlog costs incurred in emptying the two queues, starting with at most B packets in each of them.…”

“…Nevertheless, they identified the key point that cooperation between links is much more beneficial than competition (as encouraged by FM power control) for packetized traffic. A similar modeling approach was adopted in several subsequent works (e.g., see [6]). While we study the power control in a quite generic framework with emphasis on the fundamental control tradeoffs, several works have examined the distributed power control problem from the perspective of efficient MAC protocol design for ad hoc wireless networks.…”