Effects of Optical Beams on MIMO Visible Light Communication Channel Characteristics

Under 5G envision, for pushing visible light communication (VLC) channel model evolution to various non-Lambertian beams, this paper introduces the typical commercial non-Lambertian beams, such as Luxeon rebel and side emitter, into the conventional analytical VLC channel model. The numerical results illustrate that the non-Lambertian beams can significantly affect the VLC channel frequency response characteristics. Compared with the traditional Lambertian beam, Side Emitter optical beam could naturally bring up to about 56.8% VLC multi input multi output channel capacity deviation, which objectively opens a new discussion dimension for enhancing VLC transmission performance.

Characterization of the Potential Effects of EMC Filters for Power Converters on Narrowband Power Line Communications

Electromagnetic Compatibility (EMC) filters are one of the main solutions for dealing with the disturbances generated by power inverters. However, they show series/parallel resonances that introduce variations in the impedance seen from the grid. Consequently, in some cases, these filters have low impedances at resonance frequencies, which can affect Narrowband Power Line Communications (NB-PLC) due to notching effects. For that reason, the potential effects of four EMC filters on NB-PLC have been studied. Laboratory trials in a controlled environment have been carried out, in which the attenuation and the Signal-to-Noise Ratio (SNR) thresholds that define the communication’s quality have been studied. The results presented in this paper show that, although the variations of the channel frequency response are not selective enough to degrade the communication thresholds, the attenuation measured when the filter is connected near the receiver might be sufficiently high to be critical for the communications in some situations. Therefore, EMC filters might have a negative impact on NB-PLC that had not been previously considered.

COMB ADAPTIVE FILTERING ALGORITHM

The problem of multipath channel frequency response equalization in a receiver is considered. The aim is to develop an algorithm of comb adaptive filtering, which makes possible, on the one hand, to provide high rate of multirate receiver system adaptation, and on the other hand, to reduce computational complexities of real-time processing. The robustness analysis of the suggested algorithm is carried out. Two variants of comb adaptive filter are studied. For the second one a fast modification is proposed. On the assumption of multichannel communication system equalizer realization the developed algorithm is able to provide the advantage in rate almost by a factor of ten and at the same time to reduce computational complexities by a factor of three as compared with the least-mean-square algorithm as the experimental results demonstrate.

Various Channel Estimation Techniques for OFDM Systems through Different Parameters

Channel estimation in OFDM system can be performed in many ways, channel estimation is the major essential component to be calculated for the wireless communication systems (such as mobile) because these are very much effective to noise than compared to the wired communications (landlines).it has loss of data due to noise, multipath degradation, fading, etc .channel estimation is the crucial task for the effective and the reliable wireless transmission. These OFDM based systems can be improved by the pilot assisted channel estimation .As compared with the various techniques we are going to conclude that which of the available techniques are more efficient to achieve the great results. Various channel estimation techniques involved in it they are LS, LMS, RLS, MMSE, NLMS, LMMS, WLs, Sparse. It may includes the complexity of building ,effective to the noise, efficiency and comparing with many factors and probability of acquisition versus number of users are analyzed using QAM. Channel frequency response versus carrier no. and Error value versus the Sample performance after analyzing all the performance parameters we will conclude the best compared to other in all aspects. Sparse will have better performance as compared with the other six remaining channel estimations.