Resource allocation for OFDM-based decode-and-forward relay system with selective relaying

We put the major point on the selective relaying scheme, based on the OFDM-based decode-and-forward relay system. A two-stage transmission protocol is adopted. That means the source sends data to both the destination and relay on the first stage. The relay retransmits a version of the received data on the second stage, if a certain threshold is reached. First, we give the capacity expression for this system and analyze the threshold determination for selective relaying. Aiming at improving the system capacity, resource allocation and sub-carrier pairing are discussed then. According to our researches, the threshold is related to the channel coefficients of the source-destination link and the source-relay link. Simulation results show that the selective relaying scheme with the resource allocation outperforms the schemes that every/no sub-carrier transmits data via relaying in the transmission, when the system capacity is taken into account.