OFDM Bandwidth And FracUpnal Frequeiicy Offset Blind Estimation

With the development of communication techniques，communication systems withhigh quality, fast speed, and large bandwidth are more attractive for people.Orthogonal Frequency Division Multiplexing is a multi-carrier modulation techniquewith high performance. It has good capability of countering inter-symbol interferencewhich is caused by multi-path fading. The sub-carrier is orthogonal, and the frequencyspectrum is overlapped, so it can save the frequency spectrum resource greatly. OFDMcan satisfy the requirements of the bandwidth efficiency and the capability ofcountering inter-symbol interference at the same time, so it is widely used incommunication domains.The increase of the requirement for wireless communication, leads to thedeficiency of the frequency spectrum which is limited. So one of the researchdirections in this paper is OFDM bandwidth blind estimation. With the pioneer’sresearch, we analyze the OFDM bandwidth estimation based on wavelet transform,indicate the disadvantages, and propose a new OFDM bandwidth estimation based onAR model. Simulation results show that the new scheme is better than the traditionalscheme at low SNRs.We all know that the OFDM system is sensitive to carrier frequency offset. Carrierfrequency offset contains integer frequency offset, and fractional frequency offset. Theinteger frequency offset will not cause inter-carrier interference (ICI), but fractionalfrequency will. So another research direction in this paper is OFDM fractionalfrequency offset blind estimation scheme. Firstly, we analyze the ML scheme andsome improved schemes. We indicate their shortcomings, and propose another scheme.Simulation results show that the new scheme is more accurate at higher SNRs thanpresent schemes.