On performance of analog network coding in the presence of phase noise

Abstract

Analog network coding (ANC) as a simple implementation of physical layer network coding based on orthogonal frequency division multiplexing (OFDM) has been proposed to increase the network capacity and reliability of bi-directional link between a pair of users. In ANC protocol, an information between a pair of users is exchanged through two orthogonal time phases (i.e., multiple-access and broadcast phases). On the other hand, the phase noise (PN) introduces phase offset and inter carrier interference (ICI) to the useful signal. Thus, in ANC scheme PN will affect the useful signal during both multiple-access and broadcast phases. In this article, we present a performance analysis of ANC scheme using OFDM in the presence of PN in frequency-selective fading channel. We derive the total composite variance of ANC scheme in the presence of PN to obtain the signal-to-interference-plus-noise ratio (SINR) expression. Then, we evaluate the system's performance in terms of bit error rate (BER), SINR degradation, and ergodic capacity through both numerical and computer simulations. Computer simulated average BER has been consistent with the numerical results, validating the presented analysis. Our results have shown that the ANC scheme is more sensitive to the PN introduced during the broadcast phase (i.e., at destination) than during the multiple-access phase (i.e., at relay). This is because of the higher ICI to the useful signal and enhanced noise due to the imperfect self-information removal at the destination. In addition, the performance degradation of ANC scheme based on OFDM in the presence of PN is highly expressed for the PN linewidth values up to 20 Hz.

The Feasibility of Mobile Physical-Layer Network Coding with BPSK Modulation

“…where sinc(x) = sin(πx) πx . Here, a u,i represents the generation of the ICI from the k-th subcarrier on the m-th subcarrier, for k = m. Substituting ( 8) into (7), we have…”

“…We need to deal with the ICI for the signal detection in PNC based on (11). Traditionally, the overall ICI in (11) is simply treated as Gaussian noise [10], [7], [32], with mean 0 and variance…”

“…We remark that there is a similar scheme called Analog Network Coding (ANC) proposed for relay networks [7]. In TWRC, ANC differs from PNC in the downlink transmission phase.…”

“…• Second, we study the CFO impact on the BER of PNC at relay R based on BPSK modulation. Previous works [7], [10] generally treat the ICI as Gaussian noise for signal detection. For relatively high CFO in the uplink phase of PNC, however, we propose to use a belief propagation algorithm (BP) [14], [15] to address the ICI, and we show by simulation that with BP, the ICI effect on the BER of PNC could be effectively mitigated.…”