The traditional A3 event-based HO algorithms are mainly designed for the low speed (\30 m/s) networks. That aren't suitable for the high-speed railway scenario which the link quality may deteriorate sharply and the wireless channel environment may become unstable with the increase of velocity. To overcome the disadvantages of the handover algorithms in LTE high-speed railway networks, we proposed a handover optimization algorithm based on statistics, where we not only consider reference signal received power and reference signal received quality at the same time but also the rate of cell resources change. The simulation results show that the proposed algorithm has higher handover success rate and lower handover numbers. Thus unnecessary handover is reduced by up to 47 % and the novel algorithm provides success rate of 0.5-13.9 % higher than the classical A3 algorithm under different conditions of velocity, and greatly improve handover performance.

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We present a scheme based on precoding carrier allocation and independent component analysis (ICA) for indoor multiple-input-multiple-output (MIMO) visible light communication (VLC). In order to improve the reliability of the ICA algorithm for the mixed signal separation, at the sending end, frequency doubled-carriers are employed to module the parallel data which ensure that the modulated signals are independent of each other. The ICA algorithm is applied to separate the mixed signal at the receiving end directly without the requirement of the channel information. Simulation results show that this indoor MIMO VLC scheme can achieve excellent performance. When the signal-to-noise ratio is equal to 14 dB, the bit error ratio (BER) reaches the level of 10 −5 . So, the communication performance is superior to that of the commonly used schemes based on the channel estimation.

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