Research On Channel Estimation Of Low-voltage Power Line Communication Based On OFDM

Power line communication uses power line as communication media for data transmission and information exchange. With the advancement of the technologies of modulation, transmission and signal procession, power line communication is developing all the while; Multi-carrier modulation substitutes for single carrier modulation and data rate increases from a few Kilobits to several Megabits. At present, power line communication comes into an era to develop with high speed. Because power line communication has several advantages, such as no need of new wire and low cost, it has drawn a lot of attentions in the fields of intelligent home LAN and broadband access. Orthogonal Frequency Division Multiplexing (OFDM) is a critical technology for the realization of broadband power line communication. It is a type of multi-carrier modulation and a technology of multiplex. OFDM utilizes several sub-carriers which are orthogonal with one another to transmit information, thus, the utilization of frequency band is enhanced greatly and the frequency selective fading and time variation in power line channel can be overcome effectively.The communication channel is the basis for communication. As it is with the wireless communication, the performance of power line communication is also constrained by the power line channel. We need use several kinds of signal processing methods to combat with influence which the complicated.power line channel does damage to power line communication, and improve the communication performance. So channel estimation is indispensable.The thesis studies the basic characteristics of the power line channel, analyses the trait of power line channel as communication intermedium, and sets up a channel model for use. Channel estimation on pilot is researched for OFDM system in low-voltage power line communication in this thesis. Based on these analysis, the block-pilot and comb-pilot arrangement of OFDM systems are analyzed and researched. Several interpolation to acquire the entire channel frequency responses are discussed and simulated in different fading channel, such as linear interpolation, third spline interpolation, time domain interpolation and Low-Pass Filter interpolation and so on.. To validate the feasibilities of different OFDM system channel estimation algorithms and analyze the performance, this thesis takes the simulations by MATLAB. According to algorithm based on comb-pilot scheme, the dissertation proposes an improved transform domain interpolation method. Simulation results show that the proposed method has better performance. It shows that the adaptive channel estimation can inhibit noise and effect ICI which Doppler frequency offset introduces to the system.