Transform domain channel estimation with null subcarriers for MIMO-OFDM systems

This paper deals with transform domain channel estimation (TD-CE) in the MIMO-OFDM system when null carriers are placed at the edges of the spectrum in order to assure band isolation from interfering signals that occupy neighboring frequency bands. Indeed, the presence of these null carriers leads to a degradation of channel estimation because of a ¿border effect¿ phenomenon when using a discrete fourier transform (DFT). First, the problems of the conventional DFT based channel estimator are presented as well as a method to reduce the impact of this ¿border effect¿. Then, the same method is used to improve the conventional discrete cosine transform (DCT) based channel estimation. Finally the efficiency of these estimators is evaluated within IEEE802.11n system context.