Joint Relay Selection and Analog Network Coding using Differential Modulation in Two-Way Relay Channels

TL;DR

This paper introduces a relay selection and analog network coding scheme using differential modulation for two-way relay channels without channel state information, improving simplicity and maintaining performance.

Contribution

It proposes a joint relay selection and analog network coding scheme with a simple Min-Max criterion, achieving near-optimal performance without requiring CSI.

Findings

The Min-Max relay selection performs nearly as well as the optimal method.

The proposed scheme effectively operates without channel state information.

Analytical SER expressions match simulation results.

Abstract

In this paper, we consider a general bi-directional relay network with two sources and N relays when neither the source nodes nor the relays know the channel state information (CSI). A joint relay selection and analog network coding using differential modulation (RS-ANC-DM) is proposed. In the proposed scheme, the two sources employ differential modulations and transmit the differential modulated symbols to all relays at the same time. The signals received at the relay is a superposition of two transmitted symbols, which we call the analog network coded symbols. Then a single relay which has minimum sum SER is selected out of N relays to forward the ANC signals to both sources. To facilitate the selection process, in this paper we also propose a simple sub-optimal Min-Max criterion for relay selection, where a single relay which minimizes the maximum SER of two source nodes is selected. Simulation results show that the proposed Min-Max selection has almost the same performance as the optimal selection, but is much simpler. The performance of the proposed RS-ANC-DM scheme is analyzed, and a simple asymptotic SER expression is derived. The analytical results are verified through simulations.