Channel Estimation Of Ofdm Based On Pilot Frequency

Orthogonal Frequency Division Multiplexing is one of the high-speed transmission technologies in wireless environment, which is mainly dividing channel into several orthogonal sub-channels in frequency domain, using a sub-carrier for modulation in each sub-channel and all sub-carrier are transmitting concurrently. It has a high efficient transmission, simple frequency domain balanced technology, it can effectively counteract frequency selective fading and can be flexibly combined with other access methods into derivative system, which has been widely adopted in high-speed data transmission system. For accurately demodulating transmission signal, receiver needs to know channel state information in order to balance receiving signal, thus channel estimation is realized as a key technology in wireless communication.Wireless communication channel of broadband wireless OFDM is different form the traditional line channel and general fixed wireless access channel. The main features of it are time and frequency selection fading which cause degree of the signal wane different in different time and subcarrier for OFDM systems. This paper first introduces the development and research status of OFDM channel estimation, then elaborates the basic principle of OFDM system, key technologies and wireless channel transmission characteristics. It emphasizes several typical channel models of OFDM, pilot frequency inserting rule, interpolating algorithm, least square(LS) and minimum mean squared error(MMSE). on that basis, it takes simulation and analysis the result by using MATLAB.