We investigate the impact of multiple transmit antennas on the performance of a SDMA/TDMA single-cell downlink system under random packet arrivals, correlated block-fading channels and non-perfect channel state information at the transmitter due to a delay in the feedback link. We derive the arrival rate stability region and the adaptive scheduling policy that stabilizes any arrival rate point inside the region without knowing explicitly the arrival statistics. Then, we apply these results to the case of .opportunistic. beamforming and space-time coding. The ability of accurately predicting the channel SNR dominates the performance of opportunistic beamforming. Hence, we propose to exploit synchronous pseudo-random beamforming matrices known a priori by the receivers in order to improve the channel state information quality. Under this scheme, it appears that for given feedback delay the relative merit of opportunistic beamforming and space-time coding (transmit diversity) strongly depends on the channel Doppler bandwidth.
Impact of multiple transmit antennas in a queued SDMA/TDMA downlink
SPAWC 2005, 6th IEEE Workshop on Signal Processing Advances in Wireless Communications, June 5-8, 2005, New York City, USA
Type:
Conference
City:
New York City
Date:
2005-06-05
Department:
Communication systems
Eurecom Ref:
1670
Copyright:
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See also:
PERMALINK : https://www.eurecom.fr/publication/1670
