Capacity gain and design trade-offs for partial-duplex OFDM wireless communications

A hybrid transmission method between classical half-duplex and full-duplex is here considered for point-to-point orthogonal frequency division multiplexing (OFDM) links experiencing frequency selective fading. This partial-duplex solution uses only a portion of the available bandwidth for full-duplex transmission. It aims to increase the overall bidirectional system rate w.r.t. an equivalent half-duplex system, relaxing at the same time the high self-interference cancelation requirements that practical full-duplex systems have to provide. In this paper, we analyze the regions of self-interference cancelation values where partial-duplex systems outperform half-duplex ones in terms of achievable spectral efficiency. We investigate the potential of the proposed hybrid method by deriving the analytical distributions of the spectral efficiency gain regions in the presence of frequency selective Rayleigh fading. For different strategies in the selection of the sub-carriers that operate in full-duplex, we highlight the role of the different parameters involved and the peculiarity of this system in terms of design flexibility.