High mobility OFDM transmission system by a new channel estimation and ISI cancellation scheme using characteristics of pilot symbol inserted OFDM signal
Takako Yamamura, Hiroshi Harada · 1999
The OFDM transmission system can effectively reduce intersymbol interference caused by multipath fading, especially in the case of broadband data transmission. Nevertheless, the delayed waves existing in a symbol degrade the transmission performance at the receiver. Therefore when the OFDM transmission system applies to a mobile radio communication system, we have to remove the influence without intricacy. This paper proposes a new scheme in order to estimate the propagation characteristics using the characteristics of the distinctive OFDM signal which is a periodically inserted pilot signal in the frequency axis before IFFT at the transmitter. Moreover, we introduce a cancellation scheme of delayed waves on the basis of the proposed estimation technique. Using these schemes, it is possible to estimate and cancel the interference of the delayed wave before FFT at the receiver. In this paper, moreover, we evaluate the estimation accuracy of the proposed estimation method and the BER performance of the proposed system under fast multipath fading environment by computer simulation. Especially, in this simulation, we utilize the evaluation format of OFDM discussed in the Multimedia Mobile Access Communication Systems Promotion Council (MMAC).