Physical-layer Network Coding Protocol Research Articles

Selective PNC in satellite-terrestrial network over non-identical fading channels

We analyze the performance of a twoway satellite-terrestrial decode-and-forward (DF) relay network over non-identical fading channels. In particular, selective physical-layer network coding (SPNC) is employed in the proposed network to improve the average end-to-end throughput performance. More specifically, by assuming that the DF relay performs instantaneous throughput comparisons before performing corresponding protocols, we derive the expressions of system instantaneous bit-error-rate (BER), instantaneous end-to-end throughput, average end-to-end throughput, single node detection (SND) occurrence probability and average end-to-end BER over non-identical fading channels. Finally, theoretical analyses and Monte Carlo simulation results are presented. Evaluations show that: 1) SPNC protocol outperforms the conventional physical-layer network coding (PNC) protocol in infrequent light shadowing (ILS), average shadowing (AS) and frequent heavy shadowing (FHS) Shadowed-Rician fading channels. 2) As the satellite-relay channel fading gets more severe, SPNC protocol can achieve more performance improvement than PNC protocol and the occurrence probability of SND protocol increases progressively. 3) The occurrence probability increase of SND has a beneficial effect on the average end-to-end throughput in low signal-to-noise ratio (SNR) regime, while the occurrence probability decrease of SND has a beneficial effect on the average end-to-end BER in high-SNR regime.

Joint Trajectory and Resource Optimization for UAV-Aided Two-Way Relay Networks

Unmanned aerial vehicle (UAV)-aided two-way relay networks with multiple terrestrial user pairs is investigated, where a fix-wing UAV is served as a two-way relay to assist information transmission. We aim to maximize the total rate of the two-way relay networks while the quality of service (QoS) being guaranteed. A novel relay strategy, namely <i>time-slots pairing</i>, is proposed by exploiting physical-layer network coding (PNC) protocol. Specifically, the UAV receives and buffers the signals from the scheduled user pair when the UAV approaches one of them, then forwards the modulated signal when the UAV is close to the other. As a result, a non-convex total rate maximization problem is formulated by joint trajectory design and resource optimization. To solve this problem, we first decompose it into three sub-problems, and then a three-step iterative algorithm that can effectively handle the non-convex problem with no worse than a polynomial complexity is developed leveraging the block coordinate descent (BCD) technique and successive convex approximation (SCA) method. Simulation results finally illustrate that: 1) Compared with amplify-and-forward (AF) or decode-and-forward (DF) protocols, the proposed design based on PNC protocol can significantly improve the total rate of the two-way relay networks; 2) the time-slots pairing relay strategy always achieves a significant enhancement on performance than the traditional non-time-slots pairing relay strategy; 3) the time-slots pairing relay strategy is more favorable for the mobile PNC relay networks since it can well resist the degradation of the entire networks caused by users&#x2019; increased service quality requirements.

Performance Analysis of Two-Way Satellite-Terrestrial Relay Network with SWIPT.

In this paper, we investigated the performance of a two-way satellite-terrestrial DF relay network with asymmetric simultaneous wireless information and power transfer (SWIPT). In particular, selective physical-layer network coding (SPNC) was employed in the proposed network, improving the throughput performance. We derived the expressions of system average end-to-end throughput and single node detection (SND) occurrence probability. Furthermore, to observe the effects of the power splitting (PS) coefficient on the energy efficiency performance, the expressions of energy harvested in the physical-layer network coding (PNC) and SPNC protocol were also derived. Finally, theoretical analyses and Monte Carlo simulation results are presented to show: (i) SPNC protocol outperforms the conventional PNC protocol in the two-way satellite-terrestrial relay network with SWIPT in infrequent light shadowing (ILS), average shadowing (AS), and frequent heavy shadowing (FHS) Shadowed-Rician fading channels; (ii) as the channel state gets worse, SPNC protocol can achieve more performance improvement than PNC protocol; (iii) as the PS coefficient increases, the average end-to-end throughput performance increases progressively, and the average energy efficiency performance increases progressively within a certain range, while decreasing in the others.

An Optimal Power Allocation for the Two-Way Relay System Using Physical-Layer Network Coding

In this letter, an optimal power allocation in the two-way relay channel of four transmission nodes employing the physical-layer network coding (PNC) protocol is proposed to improve the network sum-rate of the two-way relay system. The optimal power allocation is obtained by maximizing the network sum-rate of the PNC protocol under a sum-power constraint in a Rayleigh fading channel environment. Analytical and simulation results show that the proposed power allocation can improve the network sum-rate. Furthermore, compared with the equal power allocation scheme, the proposed power allocation scheme can achieve much higher network sum-rate performance.

Optimal Energy-Efficient Power Allocation and Outage Performance Analysis for Cognitive Multi-Antenna Relay Network Using Physical-Layer Network Coding

In this paper, we investigate power allocation scheme and outage performance for a physical-layer network coding (PNC) relay based secondary user (SU) communication in cognitive multi-antenna relay networks (CMRNs), in which two secondary transceivers exchange their information via a multi-antenna relay using PNC protocol. We propose an optimal energy-efficient power allocation (OE-PA) scheme to minimize total energy consumption per bit under the sum rate constraint and interference power threshold (IPT) constraints. A closed-form solution for optimal allocation of transmit power among the SU nodes, as well as the outage probability of the cognitive relay system, are then derived analytically and confirmed by numerical results. Numerical simulations demonstrate the PNC protocol has superiority in energy efficiency performance over conventional direct transmission protocol and Four-Time-Slot (4TS) Decode?and-Forward (DF) relay protocol, and the proposed system has the optimal outage performance when the relay is located at the center of two secondary transceivers.