Simulation And Realization On The Access Technology For Local Area Network Of Visible Light

The local area network system is analysed in this paper, and multi-channel access technology is proposed. In particular the routing algorithm and routing metric, as well as multi-channel assignment techniques remain to be further reinforced, Cross-layer design is one of the hot research spot in the research field. Taking into account the time varying nature of the wireless environment(such as the nodes mobility, links instability, the unreliability of wireless transmission, etc.), this thesis mainly focuses on the study of the multi-channel assignment and cross-layer routing protocol.This dissertation is mainly divided into four parts:(1) The Phong model was used to analyze and simulate the distribution of the indoor optical power, compared with the generally Lambert model, the analytical results based on the Phong model are more accurate; On this basis, taking OOK as an example, the indoor multipath noise for different transmission rate was analyzed and simulated.(2) The white LED’s light-emitting principle and modulation characteristics have been analyzed, the transmitter and receiver circuits of LED have been designed. A variety of LED’s modulation bandwidth characteristics have been tested. The equalizer circuit has been designed based on the frequency response curve of LED, the bandwidth of system has been improved by the equalizer circuit. The influence of background noise and interference in indoor visible light communications have been studied and tested.(3) Considering the factors impacting the performances of communication system, including the inter-symbol-interference caused by multi-path, the background noise interference and the bandwidth restriction by LED, the performances of OOK, PPM and OFDM is simulated and analyzed.(4) The application of cross-layer in the multi-channel wireless mesh network is analyzed. The traditional multi-channel routing protocols just ameliorated routing metric or MAC protocol, and still adopt hierarchical structure. The thesis proposed a cross-layer routing protocol called CLRP for multi-channel wireless mesh network. This protocol combines the CAPC algorithm and ORBA protocol and modifies them accordingly. The results of simulation show that CLRP protocol outperforms the traditional hierarchical structure in throughput, packet delivery ratio and the time of routing establishment.