Abstract
In this paper, we study resource allocation problem in orthogonal frequency division multiple access multiple-input multiple-output (OFDMA-MIMO) relay systems and formulate the optimal instantaneous resource allocation problem including subcarrier assignment, relay selection and power allocation to maximize system capacity. Based on the assumption that the availability of perfect channel state information (CSI) is known at the resource allocation controller, we propose a new resource allocation algorithm which can guarantee proportional fairness among users. In the proposed algorithm, a two-step suboptimal method is taken into account. Firstly, we assume equal power allocation for each user to linearize the problem and propose the subcarrier assignment and relay selection scheme based on equivalent channel gain. Secondly, we derive the closed-form expressions for power allocation through relaxing the proportional fairness constraints. Numerical simulations show that the proposed algorithm performs well in terms of satisfying proportional fairness among users in strict sense and achieving improvement on system total capacity.
Highlights
The Orthogonal Frequency Division Multiple Access (OFDMA) is regarded as a leading candidate for the fourth generation (4G) wireless communication system because of its high spectral efficiency, flexible resource allocation and inherent robustness against frequencyselective fading
We study resource allocation problem in orthogonal frequency division multiple access multiple-input multiple-output (OFDMA-Multiple-Input MultipleOutput (MIMO)) relay systems and formulate the optimal instantaneous resource allocation problem including subcarrier assignment, relay selection and power allocation to maximize system capacity
We consider a single cellular OFDMAMIMO relay communication system with a base station (BS) located in the center, relay stations (RS) distributed at the inner boundary and mobile stations (MS) separated between the inner and the outer boundaries
Summary
The Orthogonal Frequency Division Multiple Access (OFDMA) is regarded as a leading candidate for the fourth generation (4G) wireless communication system because of its high spectral efficiency, flexible resource allocation and inherent robustness against frequencyselective fading. Resource allocations of Amplify-and-Forward (AF) and Decode-and-Forward (DF) MIMO-OFDM relay systems are proposed in [1,2] respectively. Both [1] and [2] only focus on a single user scenario. A number of results have been published on resource allocation for multi-user MIMO-OFDMA relay systems [3,4,5]. Most existing research resource allocation in OFDMA-MIMO relay systems focus on maximizing the system capacity, fairness among multiple users has not received much attention. To study the resource allocation problem with proportional fairness constraint is essential for OFDMA-MIMO relay systems.
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