Outage-Based Resource Allocation for DF Two-Way Relay Networks with Energy Harvesting.

Chunling Peng,Huaping Liu,Fangwei Li,Guozhong Wang

doi:10.3390/s18113946

Abstract

A joint resource allocation algorithm to minimize the system outage probability is proposed for a decode-and-forward (DF) two-way relay network with simultaneous wireless information and power transfer (SWIPT) under a total power constraint. In this network, the two sources nodes exchange information with the help of a passive relay, which is assumed to help the two source nodes’ communication without consuming its own energy by exploiting an energy-harvesting protocol, the power splitting (PS) protocol. An optimization framework to jointly optimize power allocation (PA) at the source nodes and PS at the relay is developed. Since the formulated joint optimization problem is non-convex, the solution is developed in two steps. First, the conditionally optimal PS ratio at the relay node for a given PA ratio is explored; then, the closed-form of the optimal PA in the sense of minimizing the system outage probability with instantaneous channel state information (CSI) is derived. Analysis shows that the optimal design depends on the channel condition and the rate threshold. Simulation results are obtained to validate the analytical results. Comparison with three existing schemes shows that the proposed optimized scheme has the minimum system outage probability.

Highlights

Two-way relay (TWR) communications [1,2] to extend transmission range and improve communications reliability have been studied extensively
To better display the superiority of the proposed resource allocation scheme, three benchmark schemes: optimal α equal ρ, optimal ρ equal α and equal α and ρ are presented as a comparison
Since Algorithm 1 shows that the asymmetry of the channel affects the optimal parameters, and further affects the outage performance, this simulation chose two channel conditions to assess the system performance: symmetric channel condition d1 = d2 =

Summary

Introduction

Two-way relay (TWR) communications [1,2] to extend transmission range and improve communications reliability have been studied extensively. The traditional TWR network with two source nodes exchanging information between each other via a relay requires four time slots. Combined with appropriate network coding, the number of time slots can be reduced to two [3]. With the AF and DF protocols, plenty of significant research efforts designing optimal resource allocation schemes have been proposed, aiming at further improving essential performance objectives for such networks. A power allocation (PA) scheme for an AF-TWR system and its achievable rates over Rayleigh fading channels were studied in [6]. In [7], based on maximizing the objective rate under a total power budget, a power allocation method for a specific DF relay network by exploiting physical-layer network coding was proposed. In [8], optimization of PA and time allocation (TA)

Objectives

Results

Conclusion