Improvement on diversity gain with filter bandwidth expansion in fractional sampling OFDM receiver

A diversity scheme with fractional sampling (FS) in an OFDM receiver is investigated recently. Through FS, it is possible to separate multipath components and obtain diversity gain in the OFDM system. Expansion of the bandwidth of the total response including transmit and receive baseband filters allows the FS scheme to achieve path diversity. However, the transmit filter is designed according to the spectrum mask of the standards to avoid interference to the other communication systems. In order to achieve the maximum SNR, the same filter is commonly used in the transmitter and the receiver. In this paper, the trade-off between the SNR deterioration and the diversity gain due to the total response larger than the minimal bandwidth is investigated. Numerical results through computer simulation indicate that BER performance with the receive filter of non-minimal bandwidth shows better performance than that with the filter for maximizing the SNR in certain conditions.