A Dynamic Resource Allocation Scheme for Fairness Guarantee using Cooperative Diversity in OFDMA Systems

Orthogonal Frequency Division Multiple Access (OFDMA) is a promising technique which can provide high capacity in the wireless environments. Also cooperative communications are effectively used to achieve cooperative diversity for high reliability. In this paper, we propose the pair-based OFDMA frame structure in which cooperative users transmit their blocks in turns for achieving cooperative diversity in OFDMA systems. In order to guarantee the fairness of users we also propose a dynamic resource allocation scheme based on cooperative communications. Through the proposed scheme, user fairness can be achieved by sharing the remained capacity of users near the base station (BS) with users who are farther from the base station. For this purpose, the center-located users select their partner whose channel suffers the lowest SNR to BS among their neighbor set. Based on the partner selection results, subchannels are assigned to cooperative and non-cooperative users. Through simulations in the IEEE 802.16e system environments, it is shown that the proposed scheme outperforms the non-cooperation based scheme in terms of user fairness.