室内可见光通信网络中的多用户接入和干扰管理技术

发布时间：2018-01-18 11:29

本文关键词：室内可见光通信网络中的多用户接入和干扰管理技术　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：固态照明器件LED的快速发展给室内照明带来了深刻变革,在极高的发光效率之外,其能够进行快速光强切换的特性为信息调制创造了条件,由此产生了可见光通信技术。相对于射频通信面临日益紧缺的频谱资源,可见光通信技术具有频谱丰富且无需授权,通信保密性高,电磁兼容性好,布设灵活方便等一系列优势,并被第五代移动通信技术列为备选接入手段,其研究正由点对点链路向组网应用深化。在可见光通信网络中,由于光的传播特性和用户视场角约束,小区需要密集分布以保证用户移动时服务的连续性,这对多用户接入机制的效率提出了较高要求。另外,位于小区间交叠区域的用户同时接收多个接入点的视距传播信号,给用户解调带来了困难,因此需要制定相应的干扰管理策略。本论文围绕室内可见光通信网络中的多用户接入和干扰管理技术展开研究。论文首先总结了收发端器件特性,并对室内可见光多径传输信道进行建模,给出了蒙特卡洛仿真结果,列举并分析了常见的信号调制和多用户接入方式。然后提出了光干扰对齐的理论方法,并为2 × 2室内可见光通信网络设计了具体的预编码方法,在此基础上形成的通信算法可以依据用户误码率目标动态调节编码参数。仿真结果显示,光干扰对齐技术与随机预编码相比误码率显著下降。最后设计了采用非正交多址接入技术的室内可见光通信网络架构,提出了基于位置的多用户接入方案,通过合理的用户分组避免小区间干扰。针对小区内用户非正交接入时的功率分配问题,以用户通信容量加和或用户通信容量最小值为目标,在用户服务质量保证约束下构建相应的优化问题。由于优化问题的非凸性,采用梯度-映射算法迭代求解,并特别地采用近似变换消除最小值目标函数的不可微性。考虑到用户移动时信道估计可能发生误差,干扰对消过程的残差被引入到建模过程中。仿真结果表明,采用小区频率复用因子为2的多用户分组接入机制能够有效避免小区间干扰,而且非正价多址接入方式较正交接入方式对用户通信容量有明显的提升作用,虽然一定限度的干扰对消残差会削弱用户通信容量。
[Abstract]:The rapid development of solid-state lighting device (LED) has brought profound changes to indoor lighting. In addition to the extremely high luminous efficiency, the characteristics of fast intensity switching create conditions for information modulation. As a result, visible light communication technology. Compared with radio frequency communication is facing increasing shortage of spectrum resources, visible light communication technology has rich spectrum and no authorization, high communication confidentiality, good electromagnetic compatibility. A series of advantages, such as flexibility and convenience, are listed as alternative access means by the fifth generation mobile communication technology. The research is being deepened from point-to-point link to networking application in visible light communication networks. Due to the propagation characteristics of light and the constraints of the user's field of view, the cell needs to be densely distributed to ensure the continuity of service when the user is moving, which puts forward a higher requirement for the efficiency of the multi-user access mechanism. At the same time, the users who are located in the overlapping area of the cells receive the sight range propagation signals of multiple access points, which makes it difficult for the users to demodulate. Therefore, it is necessary to formulate the corresponding interference management strategy. This paper focuses on the research of multi-user access and interference management technology in indoor visible light communication network. Firstly, the characteristics of transceiver devices are summarized. The indoor visible light multi-path transmission channel is modeled, the Monte Carlo simulation results are given, the common signal modulation and multi-user access methods are listed and analyzed, and the theoretical method of optical interference alignment is proposed. A specific precoding method is designed for 2 脳 2 indoor visible light communication network. Based on this, the coding parameters can be dynamically adjusted according to the BER target. Compared with random precoding, the BER of optical interference alignment technology is significantly reduced. Finally, the indoor visible light communication network architecture using non-orthogonal multiple access technology is designed, and a location-based multi-user access scheme is proposed. In order to avoid inter-cell interference through reasonable user packet, aiming at the problem of power allocation for non-orthogonal access of users in the cell, the goal is to add the sum of the user's communication capacity or minimize the user's communication capacity. Due to the non-convexity of the optimization problem, the gradient mapping algorithm is used to solve the optimization problem iteratively. In particular, approximate transformation is used to eliminate the nondifferentiability of the minimum objective function. Considering that the channel estimation error may occur when the user is moving, the residual error of the interference cancellation process is introduced into the modeling process. The simulation results show that. Using the cell frequency multiplexing factor of 2 multi-user packet access mechanism can effectively avoid inter-cell interference, and the non-positive multiple access mode can obviously enhance the user communication capacity compared with the orthogonal access mode. Although a certain amount of interference cancellation residuals can weaken the user's communication capacity.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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