On spectral efficiency of using relay with opportunistic channel assignment

Relay with opportunistic channel assignment (OCA) is an intermediate wireless node, which forwards messages through temporarily unused licensed channels. The spectral efficiency of OCA relay largely depends on the channel usage. This paper shows that, with a practical model of channel usage, the OCA relay outperforms the relay with fixed channel assignment by up to 0.8 bits/s/Hz/user. This interesting result is observed through our extensive investigation of the demodulation-and-forward relay adopting various resource allocation algorithms, which include the round-robin, joint channel and power allocation, best-user selection, and combinations of them. Moreover, the communication delay of all the considered OCA relaying schemes is evaluated through Monte Carlo simulations.