ABSTRACT
The idea of subcarrier permutation at the relay station of Orthogonal frequency division multiplexing (OFDM) based relay systems, enabling an increase of the system achievable capacity as well as bit error rate reductions, was related with systems incorporating amplify and forward signal processing at relay stations. As non-transparent relay stations in the next generation wireless wide area networks will be based on Decode-and-Forward (DF) relaying, it becomes important to determine effects of subcarrier permutation (SCP) implementation in OFDM DF relay systems as well. Only the ergodic capacity of OFDM DF relay system implementing Best-to-Best SCP should be analyzed, as it is known that it is the scheme which maximizes the achievable capacity. In the scenario with unequal average signal-to-noise ratio (SNR) values on hops, one half of the ergodic capacity of the channel with the lower average SNR may be used as an upper bound of ergodic capacity in the considered relay system.
