Research On Channel Estimation In FH-OFDM System

FH-OFDM is a technology that combines frequency-hopping(FH) and Orthogonal Frequency Division Multiplexing(OFDM). It inherits the anti-multipath fading ability of OFDM systems and anti-interference of FH technology. It can not only effectively enhance the transmission rate and capacity of the wireless communication system but also effectively combat multi-path fading and interfere.In this dissertation, the basic theories of channel estimation, which are suitable for static, or fast varying channel, and their applications in FH-OFDM systems are discussed in detail. In this paper, the system performance of channel estimation based on a configuration of on-line two-dimensional pilot pattern under the frequency-selective Rayleigh fading channel, is introduced. In the first step of the proposed algorithm, the leading pilot symbol is employed for LS channel estimation to get the current channel response and then the estimated value is preserved. Next, LS scheme is also applied on the regular pilot tones which are inserted OFDM data symbol. Meanwhile, the correlation function between the symbols can be approximated as zero order Bessel function. Hence, based on the correlation and the two LS estimated values, the first order interpolation equation can be obtained. Therefore, a novel on-line two-dimensional pilot-aided channel estimation algorithm is developed. From the simulation results, the proposed channel estimation scheme has superior performance in the severe frequency-selective fading channels, and this algorithm can successfully achieve the fast channel estimation for FH-OFDM systems.