基于LDPC码的铁路轨旁设备监测数据可靠传输方法

Reliable Transmission Method for Monitoring Data of Railway Trackside Equipment Based on LDPC Code

针对轨旁监测系统数据传输可靠性要求高,而信息传输易受电力牵引、噪声信号干扰、信号传输衰减等因素影响的问题,基于低密度奇偶校验(LDPC)码研究铁路轨旁设备监测数据的可靠传输方法。LDPC码具有超强的纠错能力,由校验矩阵定义,其纠错能力主要取决于LDPC码的度分布,也就是校验矩阵的行(列)重参数,因此提出基于外信息转移图分析方法的度分布搜索算法,用于确定给定码率下规则LDPC码的最佳度分布参数。在此基础上,结合2种主要铁路轨旁监测数据的特点及其传输需求,提出3套LDPC编码方案并通过仿真计算,验证编码方案的纠错能力。仿真结果表明:给出的LDPC编码方案,可将信息传输的误码率从10-2量级降到10-6以下量级,极大地提升了铁路轨旁设备监测数据传输的可靠性。

The reliability of data transmission plays significant role in reflecting the real-time train running status, monitoring operated situation of trackside equipment. It is vulnerable to electric traction, noise interference and signal degradation and other factors. The reliability of data transmission needs to be improved. In this paper, we propose a novel method based on the strong error correcting ability of Low Density Parity Check （LDPC） code to increase the reliability of the data transmission of the trackside monitoring equipment. LDPC code is defined by parity check matrix, the error correcting ability is determined by the degree distribution which means the row （column） weight of the parity check matrix. A degree distribution optimization algorithm for regular LDPC codes based on extrinsic information transform chart is presented, and some good results are introduced. According to the characteristics and requirements of two different kinds of message types transmitted in the traekside monitoring, three kinds of LDPC codes are designed. The error correcting capability of the designed LDPC codes are investigated via simulations. Simulation results show that the bit error rate of the system decreases from 10^-2 to 10^-6, the reliability of the trackside monitoring system can be significantly improved as LDPC codes are employed.