On performance of analog network coding in the presence of phase noise
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RESEARCH
Open Access
On performance of analog network coding in the presence of phase noise Amir Ligata1* , Haris Gacanin2 and Fumiyuki Adachi3
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. 1 Introduction Although the wireless traffic demands driven by the users requirements continuously grow, available radio resources remain fixed. Intensive effort is being made in order to exploit the limited radio spectrum more efficiently and minimize the mutual interference caused by the multiuser access. Orthogonal frequency division multiplexing (OFDM) is considered to be an attractive transmission technique for broadband communications over a wireless channel. A simple implementation of physical layer network coding, known as analog network coding (ANC) using OFDM, has been proposed to increase the network capacity and reliability of bi-directional communication between a pair of users using the same channel [1-4]. In ANC, an information between a pair of users is exchanged through two orthogonal time phases; (i) in multiple-access phase both users simultaneously transmit towards the *Correspondence: [email protected] 1 Communication Department, IPSA Institute, Sarajevo, Bosnia and Herzegovina Full list of author information is available at the end of the article
relay, and (ii) in broadcast phase the relay broadcast the received signal to both users using amplify-and-forward (AF) protocol. The phase no
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