Research On Collaborative Transmission Technology Of Visible Optical Network

It is estimated that by 2030, the global mobile terminal equipment will be close to 100 billion, while the global average mobile data traffic will grow nearly 20000 times. The traditional wireless communication system based on radio frequency (RF) is an interference limited system, which faces the challenges such as shortage of spectrum resources and complex interference environment. As an emerging communication technology,visible light communication has not only high bandwidth and high rate characteristics. As a supplement to traditional wireless communication,visible light communication can provide higher indoor coverage, while supporting the perfect connection of massive equipment. Therefore, it has broad application prospects and is highly concerned by the industry.In order to meet the requirement of seamless communication, the indoor visible network includes multiple access points (APs), which may lead to strong inter-cell interference and non-uniform indoor lighting distribution, thus reducing the performance of network system. In this thesis,cooperative transmission technology is mainly studied in the homogeneous visible-light network to solve the problems of uneven illumination distribution and inter-cell interference. The main contents and innovations of this thesis are as follows:Firstly, for the problem of uneven distribution of indoor lighting in collaborative transmission scenarios, it is modeled as a joint optimization problem of lighting and communication. In order to solve this problem, a combined optimization algorithm based on harmony algorithm is proposed,i.e. harmony annealing algorithm. First, the optimization factor vector is introduced to control the visible light emitter power. Secondly, the optimization problem is based on the uniformity of illumination and the quality of user communication. In addition, in order to solve the optimization problem, this thesis presents a harmony annealing algorithm based on harmony algorithm, which can make full use of the previous optimization information in each search to improve the optimization efficiency and enhance the multi-direction search capability , So as to avoid the optimization algorithm into the local optimal solution. Finally, the simulation results show that the algorithm proposed in this thesis is superior to the traditional evolutionary algorithm in terms of convergence speed and optimization performance.Secondly, a dynamic virtual cell construction method based on cooperative game theory is proposed to solve the inter-cell interference problem. Compared with the existing optical cell construction scheme, this method firstly considers the traffic difference among users and the load factor of the center network, and dynamically adjusts the virtual cell topology. In addition, this thesis designs a novel coalition utility function,and constructs an optimal virtual cell topology based on the merging and splitting criterion in the cooperative game theory to improve the network performance. Finally, the simulation results show that the system capacity is improved by 12.7% compared with the user-centered virtual cell construction method.