Title :
Space-time block-coded multiple access through frequency-selective fading channels
Author :
Liu, Zhiqiang ; Giannakis, Georgios B.
Author_Institution :
Dept. of Electr. & Comput. Eng., Minnesota Univ., Minneapolis, MN, USA
fDate :
6/1/2001 12:00:00 AM
Abstract :
Mitigation of multipath fading effects and suppression of multiuser interference (MUI) constitute major challenges in the design of wide-band third-generation wireless mobile systems. Space-time (ST) coding offers an effective transmit-antenna diversity technique to combat fading, but most existing ST coding schemes assume flat fading channels that may not be valid for wide-band communications. Single-user ST coded orthogonal frequency-division multiplexing transmissions over frequency-selective channels suffer from finite-impulse response channel nulls (fades). Especially multiuser ST block-coded transmissions through (perhaps unknown) multipath present unique challenges in suppressing not only MUI but also intersymbol/chip interference. In this paper, we design ST multiuser transceivers suitable for coping with frequency-selective multipath channels (downlink or uplink). Relying on symbol blocking and a single-receive antenna, ST block codes are derived and MUI is eliminated without destroying the orthogonality of ST block codes. The system is shown capable of providing transmit diversity while guaranteeing symbol recovery in multiuser environments, regardless of unknown multipath. Unlike existing approaches, the mobile does not need to know the channel of other users. In addition to decoding simplicity, analytic evaluation and corroborating simulations reveal its flexibility and performance merits
Keywords :
antenna arrays; block codes; broadband networks; cellular radio; fading channels; frequency division multiplexing; interference suppression; intersymbol interference; multi-access systems; multipath channels; multiuser channels; radiofrequency interference; transceivers; transmitting antennas; FDM; MUI; ST coding; ST multiuser transceivers; chip interference; finite-impulse response channel nulls; frequency-selective channels; frequency-selective fading channels; frequency-selective multipath channels; intersymbol interference; multipath fading effects; multiuser ST block-coded transmissions; multiuser interference; single-user ST coded orthogonal frequency-division multiplexing transmissions; space-time block-coded multiple access; symbol blocking; symbol recovery; transmit-antenna diversity; wide-band third-generation wireless mobile systems; Block codes; Downlink; Fading; Frequency division multiplexing; Interference suppression; Intersymbol interference; Mobile communication; Multipath channels; Transceivers; Wideband;
Journal_Title :
Communications, IEEE Transactions on