Title :
MMSE techniques for space diversity receivers in OFDM-based wireless LANs
Author :
Bartolomé, Diego ; Pérez-Neira, Ana I.
Author_Institution :
Dept. of Signal Theor. & Commun., Univ. Politecnica de Catalunya, Barcelona, Spain
fDate :
2/1/2003 12:00:00 AM
Abstract :
This paper studies the application of the minimum mean square error (MMSE) beamformer to orthogonal frequency division multiplexing (OFDM)-based wireless local area networks. The questions here addressed are mainly the design with finite-length data and the choice of the OFDM signal domain where the beamformer is applied, either frequency or time. As OFDM signals need more samples than other modulations to stabilize the estimation of the signal statistics, how to exploit the finite-length training sequence provided for the design of equalizers becomes an important issue. The paper also shows that the usual frequency processing in OFDM is not always the best choice for the spatial beamforming, mainly for channels with a very high delay spread. Then, time processing turns out to be the best suited approach in terms of the tradeoff between performance and complexity. Additionally, novel modifications of the MMSE spatial filter are proposed to improve the raw bit-error rate performance: 1) a temporal semiblind approach that exploits the cyclic prefix and 2) windowing in the frequency domain.
Keywords :
OFDM modulation; antenna arrays; array signal processing; diversity reception; equalisers; error statistics; least mean squares methods; radio receivers; spatial filters; wireless LAN; MMSE spatial filter; MMSE techniques; OFDM signal domain; OFDM-based wireless LANs; WLAN; antenna arrays; array signal processing; bit-error rate; complexity; cyclic prefix; equalizers; finite length data; finite-length training sequence; frequency domain; minimum mean square error beamformer; modulations; orthogonal frequency division multiplexing; signal statistics; space diversity receivers; spatial beamforming; temporal semiblind approach; time processing; windowing; wireless local area networks; Array signal processing; Bit error rate; Delay; Equalizers; Mean square error methods; OFDM modulation; Signal design; Spatial filters; Statistics; Wireless LAN;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
DOI :
10.1109/JSAC.2002.807344