A chunk and power allocation algorithm for proportional fairness in OFDMA relay networks

Applying amplify-and-forward (AF) protocol to orthogonal frequency division multiple-access (OFDMA) relay networks opens questions regarding subcarrier matching and resource allocation on relay stations. In this paper we consider a chunk-based OFDMA-AF system with a single source station, single or multiple relay stations, and a single destination serving multiple users. Due to the fact that contiguous subcarriers are correlated, it is possible to group them into chunks, so as to reduce the signaling overhead and the complexity of subcarrier allocation. Another important consideration is ensuring fairness among the users of the system. We present a chunk reordering and power allocation algorithm on the relay station, with the goal of maximizing the total data rate of the system, taking proportional fairness and the modulation and coding schemes constraints into account. We use the single-subcarrier approach as a benchmark and investigate the impact of the chunk size and the number of relays on the achieved data rate, showing that the proposed algorithm achieves strong results even with large chunk sizes. The algorithm is derived for full-duplex mode and extended to multiple-relay networks by the proposed optimal relay selection strategy, which is experimentally compared to several heuristic relay selection strategies.