Full-Duplex Relaying With Improper Gaussian Signaling Over Nakagami- $m$ Fading Channels

Abstract

We study the potential employment of improper Gaussian signaling (IGS) in full-duplex relaying (FDR) with non-negligible residual self-interference (RSI) under Nakagamim fading. IGS is recently shown to outperform traditional proper Gaussian signaling (PGS) in several interference-limited settings. In this work, IGS is employed as an attempt to alleviate RSI. We use two performance metrics, namely, the outage probability and the ergodic rate. First, we provide upper and lower bounds for the system performance in terms of the relay transmit power and circularity coefficient, a measure of the signal impropriety. Then, we numerically optimize the relay signal parameters based only on the channel statistics to improve the system performance. Based on the analysis, IGS allows FDR to operate even with high RSI. The results show that IGS can leverage higher power budgets to enhance the performance, meanwhile it relieves RSI impact via tuning the signal impropriety. Interestingly, one-dimensional optimization of the circularity coefficient, with maximum relay power, offers a similar performance as the joint optimization, which reduces the optimization complexity. From a throughput standpoint, it is shown that IGS-FDR can outperform not only PGS-FDR, but also half-duplex relaying with/without maximum ratio combining over certain regions of the target source rate.

Asymmetric Modulation for Hardware Impaired Systems—Error Probability Analysis and Receiver Design

“…They particularly depend on the symbol separation between two closest possibilities with ξ r = (x m r − x n r ) being the separation between the real components and ξ i = (x m i − x n i ) being the separation between the corresponding imaginary components. Let us denote the argument of the Q-function in (28) as…”

“…In this subsection, we propose a closed form bound and approximation for the average PEP expression of the adopted system model under transmitter and receiver I/Q imbalance along with the thermal noise at receiver but negligible transmitter distortion. This simplifies the PEP expression in (28) to PEP = Q √ where = αh 2 r + βh 2 i . Following similar steps as in Appendix A, the PDF of f ( ) for the Rayleigh fading channel is given as…”

“…Hence, IGS scheme offers an additional degree of design, pertinent to its circularly asymmetric characteristics. Interestingly, IGS was proven to improve the system performance of different interference limited configurations such as cognitive radio systems [25], [26] and full-duplex relaying [27], [28]. Recently, we assumed asymmetric additive distortion and studied the benefits of employing asymmetric transmission on the achievable rate and outage probability of SISO and SIMO systems in [29] and [12], respectively.…”

Ergodic Capacity Analysis of Full Duplex Relaying in the Presence of Co-Channel Interference in V2V Communications

“…In [33], the authors studied the performance of FDR over Nakagami-m fading channels in terms of outage probability and asymptotic capacity. A similar performance analysis was carried out in [34] for FDR with decode-and-forward (DF) relaying, in which the impact of improper Gaussian signaling was investigated. Although instructive, these works were built upon the classical assumption that there is no CCI from adjacent cells.…”

Robust Improper Signaling for Two-User SISO Interference Channels

“…Proof: Since ∆ ch and ∆ φ only affect R 1 , their values describing the boundary of the rate region defined in (17) can be obtained as the solution of the maximin problem…”