Channel Estimation and Signal Detection for Space Division Multiplexing in a MIMO-OFDM System

Yasutaka OGAWA  Keisuke NISHIO  Toshihiko NISHIMURA  Takeo OHGANE  

IEICE TRANSACTIONS on Communications   Vol.E88-B   No.1   pp.10-18
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.1.10
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Multi-carrier Signal Processing Techniques for Next Generation Mobile Communications--Part 1)
Category: MIMO
orthogonal frequency division multiplexing (OFDM),  multiple-input multiple-output (MIMO),  space division multiplexing (SDM),  channel estimation,  condition number,  ordered successive detection,  

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We consider space division multiplexing in a MIMO-OFDM system for high data rate transmission. Channel estimation is very important for suppressing interference and demultiplexing signals. In a wireless LAN system such as IEEE 802.11a, only a few training symbols are inserted in each subcarrier. First, we propose a channel estimation method for a MIMO-OFDM system with two training symbols per subcarrier. The basic idea is to estimate the time-domain channel responses between the transmit and receive antennas. The array response vectors for each subcarrier are calculated by applying a fast Fourier transform to them. We then can obtain the adaptive weights to cancel the interference. We show that employing training symbols having a lower condition number of the matrix used for the channel estimation improves the estimation accuracy. Furthermore, we show the bit error rate for several signal detection schemes using the above estimated channel. It is shown that an ordered successive detection based on an MMSE criterion has excellent performance, that is, it can achieve higher-speed transmissions with a lower transmit power.