改进的基于网络编码中继转发方案

针对双向中继网络中传统中继转发协议放大信号的同时放大了噪声、可能转发错误的解码信号、中继判决结果不可靠等问题,提出两种基于互信息转发(MIF)的网络编码中继转发方案。首先,中继节点转发来自两个源端信息的硬判决结果;同时还转发其可靠度;然后,接收端将来自中继节点转发的信号及其可靠度和源端信号合并,并对合并结果进行检测和判决。详细推导了所提出两种方案接收端信噪比(SNR)的表达式,并在加性高斯白噪声(AWGN)信道两种仿真条件下进行数值仿真;同时分别在AWGN信道和瑞利信道中对各种方案误码率进行蒙特卡罗仿真。结果表明在两种信道条件下所提出方案在误码率(BER)性能上较估计转发(EF)方案相比分别有约1 dB和1~2 dB的增益。仿真实验结果说明基于MIF的网络编码方案在双向中继网络中继转发中对系统的误码性能有显著提升效果。

Improved relay forwarding scheme based on network coding

To solve the problems of traditional relaying forward protocol: amplifying both the signals and the noise, possibly forwarding incorrect decoded signals and low reliability of decision on relay node in the two-way relay system, two Mutual Information Forwarding (MIF) schemes based on network coding were suggested. Firstly, the relay node forwards the hard decisions from two source nodes, and the reliability of these hard decisions. Then the receiving terminal detects and makes a decision on the combined result, which are based on the forwarding signal from relay node and its reliability, also the signal from another source node. The expressions for the received Signal-to-Noise Ratio (SNR) were derived, and numerical simulations were done in Additive White Gaussian Noise (AWGN) channel. At the same time, Monte Carlo simulation was conducted in AWGN channel and Rayleigh channel. Results show that both two proposed schemes under two kinds of channels have 1 dB and 1-2 dB gain than the Estimate-and-Forward (EF) scheme in Bit Error Ratio (BER) performance. The simulation results show that, the network coding scheme based on MIF significantly improves BER performance in relay forward of two-way relay network.