基于非理想信道状态信息对DCO-OFDM-IM系统建模与分析  

Modeling and analysis of DCO-OFDM-IM system based on non-ideal channel state information

作　　者：何欢洁 赵黎[1] 张峰[1] HE Huanjie;ZHAO Li;ZHANG Feng(School of Electronics and Information Engineering,Xi’an Technological University,Xi',an 710021,China)

机构地区：[1]西安工业大学电子信息工程学院,西安710021

出　　处：《激光杂志》2022年第6期131-135,共5页Laser Journal

基　　金：国家自然科学基金(No.12004292);陕西省科技厅一般项目-工业领域(No.2020GY-054)。

摘　　要：针对传统DCO-OFDM-IM系统进行信道估计时没有考虑信道误差影响,导致获得非理想信道状态信息(CSI)而造成信道估计有效性降低等问题,利用最小均方误差信道估计(MMSE)算法并基于非理想信道状态信息建立了DCO-OFDM-IM系统模型,推导了其理论误码率闭合表达式。同时考虑到DCO-OFDM-IM系统中采用最大似然检测算法(ML)当调制阶数增大时存在检测复杂度高,系统传输速率低等问题,而利用对数似然检测算法(LLR)降低检测复杂度,最后采用蒙特卡罗方法进行系统仿真性能的仿真对比。结果表明:当调制阶数和索引组合相同,误码率为10^(-3)时,LLR检测算法比ML所需信噪比平均改善约2 dB;在能量比为1∶8时,采用MMSE估计比LS信道估计算法系统性能改善约4 dB;当系统信道估计误差越小时,越可能获得理想CSI,提升了信道估计有效性。In order to solve the problem of channel estimation in traditional DCO-OFDM-IM system, the least mean square error channel estimation(MMSE) algorithm was used to establish the DCO-OFDM-IM system model based on non-ideal channel state information, which did not consider the influence of channel error to obtain non-ideal channel state information(CSI) and reduce the effectiveness of channel estimation. The closed expression of theoretical bit error rate is derived. At the same time, the maximum likelihood detection algorithm(ML) in DCO-OFDM-IM system has the problems of high detection complexity and low system transmission rate when the modulation order increases, and the logarithmic likelihood detection algorithm(LLR) is used to reduce the detection complexity. Finally, the Monte Carlo method is used to compare the performance of the system. The results show that when the modulation order and index combination are the same and the bit error rate is 10^(-3), the LLR detection algorithm improves the SNR by about 2 dB compared with ML on average. When the energy ratio is 1∶8, MMSE estimation improves the system performance by about 4 dB compared with LS channel estimation. When the system channel estimation error is smaller, the ideal CSI is more likely to be obtained, which improves the effectiveness of channel estimation.

关 键 词：可见光通信 正交频分复用 索引调制 信道估计 

分 类 号：TN929.1[电子电信—通信与信息系统]