Modified data-pilot-multiplexed schemes for OFDM systems

In data-pilot-multiplexed OFDM schemes, data-interference to pilot tones causes degradation in frequency offset and channel estimation. This paper derives the best data-pilot-multiplexed scheme in terms of minimizing data-interference on pilot tones. This design gives a correlated data insertion scheme (CD) (data on the left and right adjacent tones of each pilot are correlated) and a null data insertion scheme (ND) (no data are transmitted on the left and right adjacent tones of each pilot). Both schemes outperform conventional data-pilot-multiplexed schemes (CV) significantly (over 7 dB SNR advantage at the uncoded BER of 2 times 10^-2 and pilot-to-data energy ratio (PDER) of 5 dB). With the BLUE frequency offset estimator, the CD scheme yields a better performance than the ND scheme while having a slight advantage in data throughput. A modified CD scheme is also presented which transmits the same data rate at similar complexity as the CV scheme does while achieving a significant BER improvement (over 3 dB SNR advantage at the uncoded BER of 2 times 10 ^-2 and PDER of 5 dB)