A Low Complexity Power Allocation Approach for OFDM Systems with DF Relay

This paper considers a two-hop orthogonal frequency division multiple (OFDM) wireless communication systems with a source, a decode-and-forward (DF) relay and a destination. We develop a low complexity rate adaptive power allocation strategy at the source and the relay, with respect to individual transmit power constraints, if the channel state information at the transmitter is given. To further enhance the rate of the considered systems, the OFDM sub-carriers of source to relay (SR) and relay to destination (RD) are selected and paired according to their actual channel states. Computer simulations are carried out to evaluate the proposed power allocation and sub-carriers selecting-pairing approaches.