Null-subcarrier Based Channel Estimation and Mutual Interference Reduction in MIMO OFDM Systems

MIMO-OFDM is used to increase the capacity in wireless communication in the present scenario. For coherent detection, the performance of a MIMO-OFDM system greatly depends on the channel estimation. In this paper, we made an investigation on the performance of channel estimation based on superimposed pilots and null subcarriers. This leads to two main advantages, cancel the mutual interference between OFDM symbols and the second is accurate channel estimation. The channel estimation is performed in a Rayleigh fading channel using Least Minimum Mean Square Error (LMMSE) algorithm. Results show that channel estimation based on null carriers and superimposed pilot insertion gives better performance than conventional MIMO-OFDM systems.