A comb-type pilot symbol aided channel estimation for STBC based OFDM system over frequency selective channel

In this paper, the channel estimation technique for space time block code (STBC) based multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) is investigated for multipath fading channel. The channel estimation is based on the comb-type pilot arrangement where the pilot subcarriers are placed at regular interval of each OFDM symbol block and are orthogonal between different transmitting antennas. Due to the advantages of orthogonal pilot subcarrier, the original transmitted signal is completely recovered from the mixed transmitted signal at the receiver side. The least square (LS) algorithm is adopted for estimation of channel at pilot subcarrier while the interpolation is done at data subcarrier. The performance of the developed channel estimation technique is compared with the traditional single-input single-output (SISO) OFDM system on the basis of symbol error rate (SER). The simulation results show that the STBC OFDM gives better performance than SISO OFDM and the SER decreases as the signal to noise ratio (SNR) and the number of receive antenna increases.