Research Heterogemeous Network Handover Mechanism Based On Visible Light Communication

Indoor visible light communication (VLC) which utilizes the flashing of the LED lights to transfer information in free space. It is a high-speed and environmentally friendly indoor access network technology which having a broad application market. However, due to the directionality of the light, VLC cannot provide the full coverage of the indoor service. When the user moves out of the coverage area of VLC,the connection will be interrupted. The development tendency of next generation network is the integration of heterogeneous networks, so the cooperative of indoor VLC and radio communication network will overcome shortcomings of both. When the user needs to disconnect from the radio communication node to access the visible light communication node or disconnect from the visible light communication node to access the radio communication node, how to implement an efficient vertical handover mechanism is required. At present, the simplest method is to use the hard handover method, but this approach cannot achieve seamless handover. Considering the characteristics of visible light communication and the idea of soft handover in radio communication, we can realize the seamless vertical handover based on VLC indoor positioning.In this paper, we study the vertical handover mechanism between indoor VLC and radio communication. At first, the applications of visible light positioning technology in handover are analyzed. Then, the feasibility of the handover scheme based on VLC and radio communication is analyzed. At last,the handover decision method based on multi-criteria decision is discussed. The following are three creative points included in this paper.Firstly, we propose a vertical handover mechanism of centralized control based on user location. We analyze the process of the vertical handover of the heterogeneous network based on VLC indoor positioning,and introduce the pre-handover mechanism. We also describe the working structure of the vertical handover in detail and discuss the range of the vertical handover protection areas. Using the improved triangulation positioning scheme, we study the impact of the positioning accuracy on pre-handover mechanism. The simulation results show that the improved trilateral localization algorithm can improve the accuracy of vertical positioning and upgrade the success rate of vertical handover.Secondly, we propose the vertical handover strategy based on service classification and terminal multi-network interface cooperation.Applying the multi-criteria decision method to the vertical handover between the heterogeneous network of the VLC and the radio communication improves the overall performance of the indoor access network system. We redesigned the architecture of the terminal and gateway, in addition, the service classification and analysis modules have been added. Therefore, in the process of vertical handover, the multi-network interface can be cooperated to provide services to the users,and an appropriate network will be selected for each service. Finally, we apply this decision method to the experimental platform. The experimental results show that this method can select the proper network for the service.Last, we design and implement the indoor heterogeneous network demonstration platform based on visible light communication. The platform for the actual application scenarios, which including the video services to simulate the process of vertical handover, and the current access network will be gotten from the monitoring interface.