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Optimal Cross-Layer Scheduling of Transmissions Over a Fading Multiaccess Channel

Goyal, Munish and Kumar, Anurag and Sharma, Vinod (2008) Optimal Cross-Layer Scheduling of Transmissions Over a Fading Multiaccess Channel. In: IEEE Transactions on Information Theory, 54 (8). pp. 3518-3537.

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Abstract

We consider the problem of several users transmitting packets to a base station, and study an optimal scheduling formulation involving three communication layers, namely,the medium access control, link, and physical layers. We assume Markov models for the packet arrival processes and the channel gain processes. Perfect channel state information is assumed to be available at the transmitter and the receiver. The transmissions are subject to a long-run average transmitter power constraint. The control problem is to assign power and rate dynamically as a function of the fading and the queue lengths so as to minimize a weighted sum of long run average packet transmission delays. First, we study the problem for a single-user system and obtain structural properties of the optimal policy. We obtain numerical results for the delay–power tradeoff. Then, we consider the multiuser system and obtain a value iteration algorithm for computing the optimal policy.We identify that the problem is computationally intractable and consider an approximation for the cost to go function. The approximating function provides a tight upped bound for the optimal cost function and thus a one-step value iteration could result in a close to optimal policy. A one-step value iteration is then carried out to improve upon the policy.We obtain structural properties of the one-step iterated policy and show that the resulting policy can be obtained by solving a fixed point iteration on a family of suitably modified single-user optimal control policies.

Item Type: Journal Article
Additional Information: ©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Keywords: Constrained Markov decision processes;power and rate control in wireless networks.
Department/Centre: Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited: 26 Aug 2008
Last Modified: 19 Sep 2010 04:49
URI: http://eprints.iisc.ernet.in/id/eprint/15578

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