电力线通信系统中基于OFDM/OQAM的时频结合消噪算法

Time-frequency combination de-noising algorithm based on orthogonal frequency division multiplexing/offset quadrature amplitude modulation in power line communication system

针对电力线通信(PLC)系统中存在严重影响传输性能的脉冲噪声,传统的消噪算法大都不能有效抑制脉冲噪声的问题,提出一种时频结合的消噪算法。首先,通过选择合适的门限对时域接收信号中峰值较大的脉冲噪声进行检测和置零处理;然后,在频域根据已判决的符号来重构时域尚未消除完的峰值较小的脉冲噪声,并通过迭代来提高噪声重构的准确性;最后,从频域接收信号中减去重构的脉冲噪声。在电力线多径信道下进行仿真实验,相比传统的时域消噪和频域消噪算法,所提算法在误比特率为0.01时可以分别实现2 d B和0.5 d B的性能提升,而随着误比特率的降低,它们之间的性能差距将会更大。仿真结果表明,所提出的时频结合消噪算法能够提高电力线通信系统对脉冲噪声的抵抗能力。

Focusing on the issue that the impulse noise in Power Line Communication （PLC） system greatly affects the transmission performance, and most traditional de-noising algorithm can not effectively suppress the impulse noise, a time- frequency combination de-noising algorithm was proposed. Firstly, the impulse noise with large peak in the time domain received signal was detected and zeroed by selecting the appropriate threshold. Secondly, according to the symbols that had been decided in the frequency domain, the smaller impulse noise which had not eliminated in the time domain was reconstructed, and the accuracy of the noise reconstruction was improved by iteration. Finally, the reconstructed impulse noise was subtracted from the frequency domain received signal. Simulation experiments were conducted under the multipath channel of the power line. Compared with traditional time domain and frequency domain de-noising algorithms, the proposed algorithm could achieve the performance improvement of 2 dB and 0.5 dB respectively when the bit-error rate was 0. 01. And as the bit- error rate decreased, the performance gap between them would be even greater. The simulation results show that the proposed time-frequency combination de-noising algorithm can improve the resistance of the PLC system to impulse noise.