Research On Precoding Techniques In MIMO-PLC System

Power Line Communication(PLC)is designed to utilize the existing electrical infrastructure to provide high-speed,convenient communication services without additional wiring.With the pursuit of high rates and high reliability for next-generation data services,power-line communication based on Multiple-Input Multiple-Output(MIMO)is proposed to be a research hotspot.Precoding technology is one of the important ways to improve the performance of MIMO systems.So in this thesis,the linear precoding technology based on codebook and non-codebook is deeply discussed for the power line MIMO system.And several improved precoding schemes are proposed to achieve better system performance and stronger anti-interference ability.The main research content is as follows:First,the basic principle and channel characteristics of power line MIMO system are introduced.Afterwards,several non-codebook precoding techniques are analyzed and compared.The results show that UCD algorithm achieves better BER performance.Based on this,for the high complexity of Uniform Channel Decomposition(UCD)precoding,the equivalent singular value decomposition operation in UCD is implemented by introducing a two-sided jacobi transformation,which can effectively reduce the complexity of UCD scheme while ensuring system performance.Secondly,aiming at the the mutual restriction between system performance and feedback overhead in a codebook-based precoding scheme,a limited feedback precoding algorithm based on a new power allocation scheme is proposed,which can achieve a performance gain of about 2 dB over traditional power allocation scheme.On this basis,using the correlation of adjacent subcarriers,two feedback reduction precoding algorithms based on clustering and interpolation are introduced,which can reduce the feedback overhead in the case of small performance loss.Then,to further increase the Euclidean distance between the constellations at the receiver,an orthogonalized spatial multiplexing(OSM)precoding algorithm with power allocation and phase rotation is proposed.Firstly,the segmentation method is used to simplify the parameter design process and then the related parameters of optimal precoding is determined based on the maximum minimum Euclidean distance criterion.Finally,the complexity of the maximum likelihood detection at the receiver is reduced by the OSM structure.Simulations show that the BER performance of the proposed scheme is about 1.2dB higher than OSM power precoding.Finally,the advantages and disadvantages of non-codebook and codebook precoding algorithms are compared by system link simulation,and the final solution of PLC precoding with better BER performance is given.For the poor performance of the precoding system in the harsh noise environment,the improved time-frequency joint noise cancellation algorithm is combined with the selected precoding scheme to further improve the anti-jamming performance of the system.