Research On Adaptive Spectrum Allocation Based On Channel Cognition Of Power Line Communications

With the rapid development and employment of the smart grid,powerline communication,as one of the key technology of smart grid,is facing the problems of larger user group and growing communication complexity.The traditional PLC technology can nearly meet the requirement of high transmission speed with limited spectrum resource.Although OFDM technology has been widely popularized to beat the PLC frequency selective fading and to improve the communication capacity,the system transmission reliability and the utilization efficiency of spectrum resource can still be highly improved.However,adaptive spectrum allocation algorithm could solve this problem efficaciously by allocating bit and power dynamically.The purpose of this paper is to choose the reasonable channel by cognitive technology to adapt to the time-varying channel,and also use the channel state dynamically bit and power allocation technology to improve the spectrum resource efficiency and to enhance the reliability of the power line communication syst em.Firstly,this paper introduces the basic principle of OFDM technology and the transmission properties of PLC.Then it establishes the power line channel multipath transmission model and carries out the simulation work.Also,the model of power line carrier communication based on OFDM technology will be built and lay the foundation of the later research of this paper.Next,we research the basic principle of channel cognition respectively from the passive aspect and the active aspect,in preparation for the subsequent adaptive spectrum allocation work.Passive channel cognition is based on the channel estimation technology.We try to design a new channel estimation algorithm with better comprehensive performance and use simulation software for validation.In relation to the active cognition,we design a kind of channel clustering algorithm based on channel correlation and channel state history information,which can predict the communication channel state before sending data.And its rationality will be validated by computer simulation.Finally,we design a better adaptive spectrum allocation algorithm with improved ber property and excellent complexity,which share a better comprehensive performance.If we combine the cognitive result of the further part,this method could dynamically allocate bit and power for each channel.Also it will be compared with the traditional three algorithms in the MATLAB simulation platform which has been set up already.This paper breaks through the traditional limitation which is only using the channel estimation,the passive way to cognize the PLC channel,and innovatively applies the clustering algorithm in the PLC field,puts forward an active cognitive algorithm based on channel state information correlation and designs a new adaptive spectrum allocation algorithm with better comprehensive performance.With the significant contribution of this paper,the utilization rate of spectrum could be improved effectively so that the communication system reliability could also be enhanced.