Comparison of OFDM and SC/FDE with Modified LS Channel Estimator in MIMO Channels

The LS channel estimation was modified by implementing space and time code via introducing cyclic conjugate to both the information sequence and the pilot sequence in the time-domain. The bit error rate (BER) performance of orthogonal frequency division multiplexing (OFDM) and of single-carrier transmission with frequency-domain equalization (SC/FDE) with the new channel estimator in MIMO channels is compared. Computer simulations show that the BER performance of OFDM without sub-carrier adaptive modulation and encoding is similar to SC/FDE system while the MSE of the channel estimator of OFDM system is lower when the channel Doppler frequency shift is lower in MIMO channels. The performance of OFDM becomes better than SC/FDE when Doppler frequency shift is larger.