室内可见光通信盲均衡技术研究

Blind equalization algorithm for indoor visible light communication

为了降低室内可见光通信的误码率和由于多径效应导致的码间串扰,提高系统的传输特性,研究了可见光通信系统的盲均衡算法。对室内可见光通信(Visible Light Communication,VLC)系统信道进行了建模分析,利用一种改进的冲激响应算法推导计算了室内可见光通信的冲激响应。针对最小均方算法(Least Mean Square,LMS)等需要训练序列、占用信道带宽的缺点,提出了一种基于Sigmoid函数的变步长恒模(Covariance Matrix Adaptation,CMA)盲均衡算法补偿信道损耗。实验结果显示:采用了改进的CMA算法后,系统的收敛速度更快,收敛后的稳态误差减小,均衡器对系统的跟踪效果优良,通信系统的误码率也大大下降,抗噪声能力显著提高,可以有效地改善室内VLC系统的码间串扰问题。

In order to reduce the bit error rate of indoor Visible Light Communication(VLC),reduce the Intern Symbol Interference(ISI)caused by multipath effect,and improve the transmission characteristics of the system,the blind equalization algorithm of visible light communication system is studied.The channel of indoor visible light communication system is analyzed and modeled,and the impulse response of indoor visible light communication is calculated by an improved impulse response algorithm.Aiming at the equalization algorithm of Least Mean Square(LMS),which needs training sequence and channel bandwidth,a variable step size Covariance Matrix Adaptation(CMA)blind equalization algorithm based on Sigmoid function is proposed.The experimental results show that using the improved CMA algorithm,the convergence speed is faster,reduce the steady-state error after convergence,the tracking effect of the equalizer system is excellent,the error rate of communication system is greatly decreased,the ability to resist noise interference is significantly improved,and it can effectively improve the inter symbol interference of indoor VLC system.