Orthogonal frequency division multiple access resource allocation in mobile multihop relay networks using an adaptive frame structure

Abstract

ABSTRACTFor wireless mobile multihop relay (MMR) networks, we have chosen orthogonal frequency division multiple access (OFDMA) and time division duplex as a multiple access scheme and a duplex communication technique, respectively. We have also selected nontransparent relay stations (nt‐RSs) as relay nodes to extend the MMR network coverage. Through the nt‐RSs, far‐off subscriber stations (SSs) or hidden SSs can communicate with a base station (BS) that is connected to backhaul networks. In these MMR networks, the way in which a BS and nt‐RSs use OFDMA resources (e.g., OFDMA symbols and subcarriers) and share them might reduce system capacity and network throughput. Therefore, we proposed a new adaptive OFDMA frame structure for both the BS and the nt‐RSs. The proposed scheme is the first approach that incorporates the adaptive technique for wireless MMR networks. Based on the proposed adaptive OFDMA frame structure, an adaptive OFDMA resource allocation for SSs within a BS as well as nt‐RSs was proposed. To derive the maximum OFDMA resource that nt‐RSs can be assigned and to synchronize access zones and relay zones between a superior station and its subordinate nt‐RSs, three properties are introduced: a data relay property, a maximum balance property, and a relay zone limitation property. In addition, we propose max‐min and proportional fairness schemes of the proposed adaptive frame structure. Our numerical analysis and simulations show that the proposed OFDMA allocation scheme performs better than the nonadaptive allocation scheme in terms of network throughput and fairness especially in the asymmetric distribution of subscriber stations between access zones and relay zones in the MMR networks. Copyright © 2011 John Wiley & Sons, Ltd.