Differential Modulation for Bidirectional Relaying With Analog Network Coding

Abstract

In this paper, we propose an analog network coding scheme with differential modulation (ANC-DM) using amplify-and-forward protocol for bidirectional relay networks when neither the source nodes nor the relay knows the channel state information (CSI). The performance of the proposed ANC-DM scheme is analyzed and a simple asymptotic bit error rate (BER) expression is derived.The analytical results are verified through simulations. It is shown that the BER performance of the proposed differential scheme is about 3 dB away from that of the coherent detection scheme.To improve the system performance, the optimum power allocation between the sources and the relay is determined based on the simplified BER. Simulation results indicate that the proposed differential scheme with optimum power allocation yields 1-2 dB performance improvement over an equal power allocation scheme.

Two-way amplify-and-forward relaying with carrier offsets in the absence of CSI: differential modulation-based schemes

“…For simplicity, we assume that the fading coefficients and the carrier offsets keep constant over the frame of length L and change independently from one frame to another [7,10]. The received signal at the relay at time k is then…”

“…Two-way relaying (TWR) has attracted much interest recently [1][2][3][4][5][6][7], where two source terminals communicate with each other through an intermediate relay.…”

“…Therefore, differential modulation for TWR without the knowledge of CSI is worth being exploited. Differential receivers for TWR were designed in [7,10,11]. However, perfect synchronization was assumed in [7,10], while imperfect synchronization scenario caused by different propagation delay from both sources to the relay due to the distributed nature of all nodes was investigated in [11].…”

“…Differential receivers for TWR were designed in [7,10,11]. However, perfect synchronization was assumed in [7,10], while imperfect synchronization scenario caused by different propagation delay from both sources to the relay due to the distributed nature of all nodes was investigated in [11]. To the best of our knowledge, no work has http://jwcn.eurasipjournals.com/content/2014/1/111 been reported in TWR with unknown carrier frequency offsets when CSI is not available at all nodes.…”

Transmission Protocol Design for Binary Physical Network Coded Multi-Way Relay Networks

“…Denoising essentially performs a mapping from the complex field operation in the wireless channel to the finite field operation for network coding. The DNF protocol increases the achievable throughput at high signal-to-noise ratio (SNR) [3] compared to the conventional DF relaying and DF relaying with NC due to the improved time efficiency, and increases the achievable throughput at low SNR compared to the amplify-and-forward (AF) relaying (or analog network coding) [6], [7] due to This work was supported in part by the National Science Council, Taiwan, under grant NSC 102-2218-E-001-001. the avoidance of noise amplification.…”