OFDM Synchronization And Channel Estimation In Hybrid Network Communications

In the recent years, with the rapid development of wireless communication technology, the data transmission rate increases dramatically, and the bottleneck effect of the user access rate in access network begins to highlight. Taking the advantage of the prevailing electrical wiring networks, power line communications is becoming one of the strong competitors in the last-mile access. In the meantime, because of its good performance to overcome frequency selectivity and high spectrum utilization rate, orthogonal frequency division multiplexing (OFDM) has been widely applied in wireless and power line communications.In seismic prospecting, in different geographical environment, cable and wireless data transmission between sensors is needed. And these sensors seldom move during communication. Based on the application requirement, we research the OFDM based power line and wireless communication technology, and discuss the possibility of adopting a common physical layer structure in these two kinds of communications. This thesis focuses on the OFDM timing synchronization and channel estimation in broadband power line communication, and pays attention to the compatibility of these algorithms when they are transplanted to wireless systems.The main content of the paper is listed in the following:1) Make a detailed performance comparison and complexity analysis of four classical OFDM timing synchronization algorithms over a PLC channel. And propose an improved method, which can reaches higher estimation accuracy in low SNR condition with relatively lower calculation complexity.2) Extend the channel estimation to channel related parameters estimation, which includes SNR, channel length and channel impulse response estimation. Based on the analysis of the available algorithms, propose a modified SNR estimation assisted channel length estimation method. And use the estimated channel length to optimize the performance of the classical channel estimation algorithms.3) Research the first channel tap selection algorithm, make some modification to the available method and attempt to propose a new solution. Combine all the studied algorithms together and make a brief analysis of their mutual influence.4) Transplant the research result in PLC channel to a wireless channel; make some necessary modification and present performance verification.