可见光辅助中继通信系统与功率分配方案

doi:10.19665/j.issn1001-2400.2020.01.014

摘要/Abstract

摘要：

当室内可见光通信链路因遮挡产生阻塞引起通信中断时,需要通过辅助中继对信号进行转发,因此建立了室内可见光通信辅助中继系统模型。首先分析了室内可见光通信系统中存在链路阻塞时室内光源在屋顶的位置约束关系,通过利用办公室顶灯作为信号光源和中继,采用非对称削波直流偏置光正交频分复用实现辅助中继的信号复用,保证了遮挡信号中继传输的同时,保持与其目的终端之间的通信;随后利用遗传算法对光源端和中继端的功率进行优化分配以优化系统性能,并在遮挡情况下与等功率分配方案的系统误码率性能进行了比较。结果表明,当直接通信链路阻塞时,最优功率分配方案的辅助中继系统比采用等功率分配的系统损耗小3 dB。

关键词: 可见光通信, 非对称削波直流偏置光正交频分复用, 功率分配, 遗传算法

Abstract:

When the indoor visible light communication link is interrupted due to occlusion blocking, the signal needs to be forwarded through the auxiliary relay, and therefore, an indoor visible light communication auxiliary relay system model is established. First, the positional constraint relationship of indoor light source on the roof when there is link blockage in the indoor visible light communication system is analyzed by using the office ceiling light as the signal light source and relay, and the asymmetrically multiplexing DC offset optical orthogonal frequency division multiplexing is used to realize the auxiliary relay signal multiplexing, which ensures the occlusion signal relay transmission while maintaining its target terminal. Then the genetic algorithm is used to optimize the distribution of the power at the source and the relay to optimize the system performance, and the BER performance of the equal power allocation scheme is compared in the occlusion case. The results show that when the direct communication link is blocked, the system loss of the auxiliary relay system with the optimal power allocation scheme is 3 dB less than the system with equal power allocation.

Key words: visible light communication, asymmetrically clipped DC biased optical offset frequency division multiplexing, power allocation, genetic algorithm

中图分类号:

TN92

谢凡,冯莉芳. 可见光辅助中继通信系统与功率分配方案[J]. 西安电子科技大学学报, 2020, 47(1): 95-103.

XIE Fan,FENG Lifang. Visible light assisted relay communication system and a power allocation scheme[J]. Journal of Xidian University, 2020, 47(1): 95-103.

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性能参数指标		参数值
中心发光强度/lx		900
光源S₁位置/m		(1.25,1.25,3)
发射机R₁位置/m		(-1.25,1.25,3)
光源S₂位置/m		(-1.25,-1.25,3)
发射机R₂位置/m		(1.25,1.25,3)

信号功率/mW	4QAM		16QAM		64QAM
信号功率/mW	K_S	K_R	K_S	K_R	K_S	K_R
1	0.436 876	0.318 916	0.439 656	0.333 124	0.454 312	0.379 907
5	0.423 448	0.301 233	0.429 348	0.315 507	0.441 563	0.368 393
10	0.411 875	0.282 831	0.426 487	0.299 296	0.435 625	0.356 641
15	0.384 340	0.266 483	0.421 261	0.291 798	0.429 718	0.343 750
20	0.380 153	0.264 887	0.420 277	0.288 361	0.425 384	0.326 563
25	0.375 749	0.257 735	0.418 469	0.282 926	0.419 841	0.309 375
30	0.373 128	0.255 938	0.405 636	0.282 500	0.418 976	0.309 184

性能参数指标			参数值		性能参数指标				参数值
房屋	反射系数	墙壁,天花板		0.8	遮挡物	高度/m	1.8
房屋	反射系数	地面		0.3	遮挡物	位置/m	(0.5,1.2,0)
发射机	半功率角Φ/(°)			70	接收机	有效接收面积A/cm²				1
	位置/m	S₁		(1.25,1.25,3)	接收机	接收机高度h_d/m					0.7
		R₁		(-1.25,1.25,3)	视场角/(°)					85
		S₂		(-1.25,-1.25,3)	位置/m			D₁		(0,1.2,0.7)
		R₂		(1.25,1.25,3)	位置/m			D₂		(-1.2,1.2,0.7)
载波数N			256		总功率/mW				1000
循环前缀的长度N_g			32		噪声功率σ/mW				1