Title :
Adaptive MAP receiver via the EM algorithm and message passings for MIMO-OFDM mobile communications
Author :
Kashima, Tsuyoshi ; Fukawa, Kazuhiko ; Suzuki, Hiroshi
Author_Institution :
Tokyo Inst. of Technol., Japan
fDate :
3/1/2006 12:00:00 AM
Abstract :
This paper proposes two new types of maximum a posteriori probability (MAP) receivers for multiple-input-multiple-output and orthogonal frequency-division multiplexing mobile communications with a channel coding such as the low-density parity-check code. One proposed receiver employs the expectation-maximization algorithm so as to improve performance of approximated MAP detection. Differently from a conventional receiver employing the minimum mean-square estimation (MMSE) algorithm, it applies the recursive least squares (RLS) algorithm to the channel estimation in order to track a fast fading channel. For the purpose of further improvement, the other proposed receiver applies a new adaptive algorithm that can be derived from the message passing on factor graphs. The algorithm exploits all detected signals but one of targeted time, and can gain a considerable advantage over the MMSE and RLS. Computer simulations show that the first proposed receiver is superior in channel-tracking ability to the conventional receiver employing the MMSE. Furthermore, it is demonstrated that the second proposed receiver remarkably outperforms both the conventional and the first proposed ones.
Keywords :
MIMO systems; OFDM modulation; adaptive estimation; approximation theory; channel coding; channel estimation; expectation-maximisation algorithm; fading channels; graph theory; least mean squares methods; maximum likelihood detection; message passing; mobile radio; radio receivers; recursive estimation; MAP receiver; MIMO; MMSE; OFDM; RLS; adaptive algorithm; approximated MAP detection; channel coding; channel estimation; expectation-maximization algorithm; factor graph; fast fading channel; maximum aposteriori probability; message passing; minimum mean-square estimation algorithm; mobile communication; multiple-input-multiple-output; orthogonal frequency-division multiplexing; recursive least squares algorithm; signal detection; Channel coding; Expectation-maximization algorithms; Frequency division multiplexing; Least squares approximation; MIMO; Message passing; Mobile communication; Parity check codes; Recursive estimation; Resonance light scattering; Channel estimation; expectation-maximization (EM) algorithm; factor graph; low-density parity-check code (LDPC); maximum a posteriori probability (MAP); message passing; multiple-input–multiple-output (MIMO); orthogonal frequency-division multiplexing (OFDM);
Journal_Title :
Selected Areas in Communications, IEEE Journal on
DOI :
10.1109/JSAC.2005.862396