Cross-Layer Combining of Truncated ARQ with Adaptive Modulation and Coding in Full Duplex Systems

Abstract

In this paper, we design a bidirectional communication system employing adaptive modulation and coding (AMC) at the physical layer combined with truncated ARQ at the data link layer. The AMC in this system is made more robust with the help of a maximum a posteriori (MAP) optimal estimation with pilot symbol assisted modulation (PSAM) channel prediction technique. This prediction technique takes into account the latency in receiving the channel state information (CSI). We then considered this system operating in in-band full-duplex (FD) configuration and compared it with its half-duplex (HD) counterpart. The performance of the two configurations was compared under various channel conditions in terms of average spectral efficiency (SE). Numerical results obtained show that, even with residual self-interference (SI) signal in the received signal, the system in FD configuration outperforms that in HD configuration. In fact, when the SI signal is assumed to be completely canceled and the channel prediction is imperfect, the FD average SE more than doubles the HD average SE at low average signal-to-noise ratio (SNR).