A Practical Feasibility Study of a Novel Strategy for the Gaussian Half-Duplex Relay Channel

Abstract

This paper presents a practical feasibility study of a novel two-phase three-part-message strategy for half-duplex relaying, which features superposition coding and interference-aware cancellation decoding. Aiming to analyze the performance of the proposed scheme in the non-asymptotic regime, this paper evaluates the spectral efficiency with finite block-length and discrete constellation signaling and compares it with the theoretical performance of Gaussian codes with asymptotically large block-lengths. The performance evaluation is carried out on an LTE simulation test bench. During each transmission phase, the modulation and coding scheme is adapted to the channel link qualities to enhance the overall spectral efficiency. A single-antenna source and relay, and a multi-antenna destination are assumed. The static Gaussian and two frequency selective channel models are considered for the proposed scheme. A spectral efficiency comparison with a baseline scheme (non-cooperative two-hop transmission, i.e., the source-destination link is absent) and with the point-to-point transmission strategy (no relay) is presented. The results confirm that physical-layer cooperation and multi-antennas are critical for performance enhancement in heterogeneous networks. Moreover, they show that physical layer cooperation advantages are within practical reach with existing LTE coded-modulation and interference-mitigation techniques, which are prevalent in modern user-equipment.