Practical physical layer network coding

Abstract

Physical-layer network coding (PNC) is a new technology which has the potential to increase network throughput beyond existing standards based on routing. Despite the fact that PNC has been well investigated from information-theoretic point of view, only a few partial prototypes have been reported in the literature. The implementation of a PNC system is burdened with many challenges such as carrier-phase, symbol and frame asynchrony. In this research, we mainly focus on software-defined radio prototyping of a two-way relay network utilizing PNC relaying. We present the first real-time implementation of a generalized PNC algorithm, namely compute-and-forward relaying. In addition, we propose an improved compute-and-forward relaying scheme which simplifies the use of power-of-two size constellations typically used in practical communication systems. The presented testbed provides a valuable platform for verification of the theoretical research on PNC and evaluation of synchronization requirements. Our experimental results show that when the signal-to-noise ratio is high, PNC relaying outperforms other relaying strategies in terms of the network throughput. In addition, we propose a new method of multiplierless pulse-shaping filter design which allows essential reduction of the hardware utilization as well as out-of-band power. Therefore, a multiplierless filter designed with the proposed method is especially suitable for FPGA/VLSI implementation.