A random walk prediction (RWP)-based channel model is founded in the underground-mining (UM) visible-light communication (VLC) network. Among the factors that influence the communication performance of the UM-VLC network, the most significant ones are the arbitrary positioning and orientation of optical transmitters and receivers, tunnels with irregular walls, shadowing by machinery or miners, and scattering from dust clouds. This analysis allows for the development of a more realistic RWP-based channel model. These factors are integrated into a single-channel model that facilitates the derivation of complex expressions. The parameters are the received power of the RWP-based channel model, channel impulse response, root mean square delay spread, signal-to-noise-ratio, and bit error rate. The simulation results show that the RWP-based channel model meets the practical requirements better than other models in the reference papers.

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A novel architecture with full-duplex direct communications(FDDC) between any two ONUs for optical access network is proposed in this paper. By designing combination switch(CS) ingeniously, the architecture is finished to realize FDDC between any two ONUs in wavelength division multiplexing passive optical networks(WDM-PONs). By utilizing interconnected optical fibers between ONUs, the network has achieved threelevel protections(feeder optical fiber protection, distributed optical fiber protection and interconnected optical fiber protection). By constructing expansion module(EM), the network can be flexibly expanded and optimized, and the CapEx and OpEx of network can be greatly reduced. Finally, by the simulation and analysis, the effectiveness of the proposed architecture is demonstrated.

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