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针对LED通信系统中信道估计性能低的问题,提出了将正交频分复用(OFDM)系统与多输入多输出(MIMO)技术相结合的可见光通信系统及其基于信噪比的自适应信道估计算法。通过对最小二乘法(LS)、最小均方误差(MMSE)、离散傅里叶变换改进最小二乘法(LS-DFT)、离散傅里叶变换改进最小均方误差(MMSE-DFT)以及分布式压缩感知同步正交匹配追踪(DCS-SOMP)5种信道估计方法的研究,确定了信噪比的临界阈值。当信噪比低于临界阈值时,采用MMSE-DFT算法进行信道估计;当信噪比高于临界阈值时,选用DCS-SOMP算法进行数据重构并恢复信道脉冲响应矩阵。仿真结果表明,当信噪比为1dB~40dB时,所提算法的均方误差得到有效降低(2.95dB~15dB),且LED通信系统的通信质量得到提高。
Aiming at the problem of low channel estimation performance in LED communication system, a visible light communication system combining Orthogonal Frequency Division Multiplexing (OFDM) system with multiple input multiple output (MIMO) technology and its adaptive channel based on signal to noise ratio Estimation algorithm. Based on LSE, MMSE, LS-DFT, MMSE-DFT, and distributed The study of five kinds of channel estimation methods based on compressed sensing synchronous orthogonality matching tracking (DCS-SOMP) has determined the critical threshold of signal-to-noise ratio. When the signal to noise ratio is lower than the critical threshold, MMSE-DFT algorithm is used to estimate the channel. When the signal to noise ratio is above the critical threshold, DCS-SOMP algorithm is used to reconstruct the data and restore the channel impulse response matrix. The simulation results show that when the SNR is 1dB ~ 40dB, the mean square error of the proposed algorithm is effectively reduced (2.95dB ~ 15dB), and the communication quality of LED communication system is improved.