Proportional fair scheduling combined with adjustment of two hop transmission time for relay-aided OFDMA systems

For the orthogonal frequency division multiple access (OFDMA) networks that adopt relaying technology, this paper suggests a novel two hop scheduling scheme that adjusts the transmission time of each hop. Since relays cannot forward data until they receive data from base station, the data transmission consists of two hops for base station to relay and relay to mobile station. In this case, wireless resources can be wasted due to the asymmetry of two hops. To cope with this, this paper suggests a scheduling scheme that allocates the wireless resources based on proportional fairness and adjusts the transmission time of each hop in order to fully utilize the allocated resources. With the proposed scheme, the network throughput can be increased while the fairness is guaranteed. By using simulation, we show that the performance of the proposed scheme is higher than those of the scheme without relays and the scheme which does not adjust the transmission time of two hops.