电力线信道具有噪声强、衰减大的特点,信号通过信道后变化剧烈。OFDM电力线通信系统需要有效的增益控制策略。设计了一种两级调整结构的自动增益控制(AGC,auto gain control)方法,通过采用两级环路滤波能够有效应对信号突变,保证AGC的收敛速度和稳定性。同时加入能量检测单元,有效降低系统待机功耗。仿真结果表明,两级调整结构的AGC具有更好的收敛特性,能够满足电力线通信的要求。
An optimized channel estimation algorithm based on a time-spread structure in OFDM low-voltage power line communication(PLC) systems is proposed to achieve a lower bit error rate(BER).This paper optimizes the best maximum multi-path delay of the linear minimum mean square error(LMMSE) algorithm in time-domain spread OFDM systems.Simulation results indicate that the BER of the improved method is lower than that of conventional LMMSE algorithm,especially when the signal-to-noise ratio(SNR) is lower than 0 dB.Both the LMMSE algorithm and the proposed algorithm are implemented and fabricated in CSMC 0.18μm technology. This paper analyzes and compares the hardware complexity and performance of the two algorithms.Measurements indicate that the proposed channel estimator has better performance than the conventional estimator.
电力线通信(Power Line Communication,PLC)凭借以电力线为通信介质,成为最具优势的通信方式.针对PLC系统中RS码多码率的问题,基于RiBM算法和uiBM算法,设计一种适合PLC系统的多码率RS码译码器.该译码器复杂度低,资源使用量少,易于VLSI实现.该译码器已在一款PLC芯片上得到应用.
为了寻找适用于电力线载波通信(power line communications,PLC)系统的新调制解调方式,在电力线信道下对滤波多音调制(filtered multitone modulation,FMT)与正交频分复用(orthogonal frequency division multiplexing,OFDM)系统进行了性能比较。仿真结果表明,在给定的信道模型下,FMT系统在对抗频域脉冲噪声和窄带干扰方面优于OFDM系统,但在时域脉冲噪声下,性能比OFDM系统差。
