Two-way denoise-and-forward network coding opportunistic relaying with jointing adaptive modulation relay selection criterions

Abstract

To improve the performance of the two-way denoise-and-forward network coding opportunistic relaying systems (TW-DNF-OR), two novel best-relay selection criterions are presented, which are the jointing adaptive modulation max–min criterion (AM-MM) and the jointing adaptive modulation maximum harmonic mean criterion (AM-MHM). In the proposed AM-MM and AM-MHM criterions, the effect of the modulation schemes used at both sources is exploited perfectly by integrating the adaptive modulation with the max–min and maximum harmonic mean criterions. On the basis of the proposed AM-MM and AM-MHM criterions, the authors analyse the symbol error probability (SEP) of the TW-DNF-OR systems under independent and non-identically distributed Rayleigh fading channels, and obtain the analytical expressions to the approximate upper bounds of the overall average SEPs. The comparison analyses show that the average SEP of TW-DNF-OR is improved greatly when the proposed jointing adaptive modulation best relay selection criterions are used. Moreover, in certain channel realisations or signal-to-noise ratio regions, the adaptive modulation non-selection TW-DNF-OR systems outperform the conventional best relay selection systems in which the adaptive modulation is not integrated with the best relay selection criterions.