Abstract
The power allocation problem for multiuser wireless networks is considered under the assumption of amplify-and-forward cooperative diversity. Specifically, optimal centralized and distributed power allocation strategies with and without minimum rate requirements are proposed. We make the following contributions. First, power allocation strategies are developed to maximize either (i) the minimum rate among all users or (ii) the weighted-sum of rates. These two strategies achieve different throughput and fairness tradeoffs which can be chosen by network operators depending on their offering services. Second, the distributed implementation of the weighted-sum of rates maximization-based power allocation is proposed. Third, we consider the case when the requesting users have minimum rate requirements, which may not be all satisfied due to the limited-power relays. Consequently, admission control is needed to select the number of users for further optimal power allocation. As such a joint optimal admission control and power allocation problem is combinatorially hard, a heuristic-based suboptimal algorithm with significantly reduced complexity and remarkably good performance is developed. Numerical results demonstrate the effectiveness of the proposed approaches and reveal interesting throughput-fairness tradeoff in resource allocation.
Highlights
A new form of diversity, namely, cooperative diversity, has been introduced to enhance the performance of wireless networks [1, 2]
Optimal power allocation is performed for the admitted users. We show that this 2-stage optimization problem can be equivalently reformulated as a single-stage problem which assists us in developing a heuristic-based approach to efficiently solve the underlying joint admission control and power allocation problem
The equal power allocation (EPA) scheme in which each relay distributes power among all relayed sources is included as reference
Summary
A new form of diversity, namely, cooperative diversity, has been introduced to enhance the performance of wireless networks [1, 2]. This paper considers resource allocation problems for multiuser relay networks under two different scenarios. Due to limitation of power resource, minimum rate requirements for all users may not be satisfied simultaneously This motivates the investigation of admission control where users are not automatically admitted into the network. We propose an algorithm to solve the joint admission control and power allocation problem Such algorithm first aims at maximizing the number of users that can be admitted while meeting their minimum rate requirements. The complexity in terms of running time of the former is much lower than that of the latter Since such heuristic-based approach uses convex optimization, the joint admission control and power allocation problem can be solved efficiently even for large networks.
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