可见光混合二维CAP-DPIM调制

A hybrid two dimensional CAP-DPIM modulation scheme for visible light communication systems

为了提高基于白光LED的可见光通信系统传输性能,本文围绕提高频谱效率及可靠性展开研究,提出一种兼顾功率效率和频谱效率的混合调制方案。该方案采用无载波幅度相位调制(CAP)与脉冲间隔调制(DPIM)相结合,发送端在DPIM的脉冲时隙上加载直流偏置CAP信号(DCO-CAP),生成混合调制信号,接收端采用提出的修正硬判决检测算法及最大似然检测完成混合调制信号的串行解调。考虑室内环境光的影响,推导了基于Lambertian光照模型并在高斯信道下二维DCO-CAP-DPIM方案的误比特率(BER)及误帧率(FER)解析表达式,仿真实验验证了理论解析式的准确性以及提出的修正硬判决检测算法的有效性。对于8 m×6 m×3 m实验场景,通过数值仿真,分析对比了DCO-CAP,以及不同混合调制在相同频带利用率下的性能,结果表明:当频谱效率相同时,混合二维DCO-CAP-DPIM调制系统较单一调制可靠性提高2-12 dB。且调制参数相同时,基于硬判决的修正算法使系统可靠性提高5 dB。

Aiming to improve the transmission performance of indoor visible light communication system based on white LED,while focuses on improving the spectrum efficiency and reliability,this paper proposes a hybrid modulation scheme that takes both power efficiency and spectrum efficiency into account.In this scheme,carrier-free amplitude-phase modulation(CAP)combines with pulse interval modulation(DPIM),which help the transmitter loads DC offset CAP signal(DCO-CAP)on the pulse slot of DPIM to generate hybrid modulation signal.The receiver uses the proposed modified hard decision detection algorithm and maximum likelihood detection to complete serial demodulation of hybrid modulation signal.Considering the influence of indoor ambient light,the analytical expressions of bit error rate(BER)and frame error rate(FER)of two-dimensional DCO-CAP-DPIM scheme in Gaussian channel based on Lambertian illumination model are derived.Simulation experiments verify the accuracy of the theoretical analytical formula and the effectiveness of the modified hard decision detection algorithm.The performances of DCO-CAP and different hybrid modulations under the same frequency band utilization are analyzed and compared through numerical simulation for the experimental scene of 8 m×6 m×3 m.The results show the reliability of the hybrid two-dimensional DCO-CAP-DPIM modulation system is 2-12 dB higher than that of the single modulation system when the spectrum efficiency is the same while the correction algorithm based on hard decision can improve the system reliability by 5 dB when the modulation parameters are the same.