Research On MAC Protocols Of Hybrid VLC-RF Network Based On Visible Light Communication

Visible Light Communication(VLC) is an emerging high-speed wireless communication technology. It mainly uses the light emitting diode’s(LED) characteristics which are fast response speed, strong stability and so on. Signals are modulated to the LEDs for data transmission on visible light. This communication technology has been proved to be energy-saving for its combination with LEDs’ illumination, also it has other advantages such as strong compatibility with other wireless technologies and good networking flexibility. Combined with illumincation, visible light is used in downlink of VLC communication system naturally. While the traditional radio frequency(RF) usually has a larger coverage and an omnidirectional link, so it can be used together with visible light to form a hybrid network for an ideal indoor VLC system. To solve the questions in the media access control(MAC) protocol, we maily study the multiple access technology and channel allocation technology of the hybrid VLC-RF network. The main research contents and results are summarized as follows:1. A Parallel Transmission-MAC(PT-MAC) protocol for the hybrid VLC-RF network is introduced based on the carrier sense multiple access with collision avoidance(CSMA/CA) mechanism. The protocol puts forward the concept of parallel transmission: users can transmit their packets together in different channels at the same time, and a single user can transmit its packets through both channels at the same time. We establish a two-dimensional Markov chain model to analyze the users’ access process. The parameters of the nodes and the network are considered to calculate the proportion of the downlink channel allocation. The operational mechanism and the details of the protocol are discribed. Simulation result shows that the throughput of the PT-MAC protocol is better than other protocols and the network gains an ideal efficiency performance.2. A downlink channel resource allocation sheme based on the non-cooperative game theory is presented. Channel selection and resource allocation techniques are the key technologies which affect network performance and ensure user quality of service(QoS). This paper presents a non-cooperative game theory to allocate resources to the users with service request in the hybrid network. Combining the relevant parameters of the channels and users’ QoS parameters, we introduce the utility function fomulas. An improved particle swarm optimization algorithm is proposed to calculate the optimal solution. The simulation results shows: when the total network utility reach the maximum, the network channel allocation gains the best result. This allocation result improves the throughput of both the network and the channels, also it improves the utilization efficiency of channel resources.3. Aimed at the application of the hybrid VLC-RF network in the mine network, we introduce a reliable broadcast MAC protocol for different traffic demand under different scenarios in the mine after the system architecture analysis and. The server controls the different traffic upload scheme through changing the broadcasted beacon. The specific interaction is described in detail and the frames’ structure design is given. Simulation shows that the all functions of different traffic upload can be effectively achieved.