Experiments on Coherent Adaptive Antenna Array Diversity Receiver Based on Antenna-Weight Generation Common to Paths in W-CDMA Reverse Link

Hidekazu TAOKA  Shinya TANAKA  Taisuke IHARA  Kenichi HIGUCHI  Mamoru SAWAHASHI  

IEICE TRANSACTIONS on Communications   Vol.E86-B   No.1   pp.191-205
Publication Date: 2003/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Multiple Access and Signal Transmission Techniques for Future Mobile Communications)
DS-CDMA,  adaptive antenna array,  interference suppression,  

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This paper presents laboratory and field experimental results of the coherent adaptive antenna array diversity (CAAAD) receiver employing receiver antenna-weight generation common to all Rake-combined paths (hereafter path-common weight generation method) in the W-CDMA reverse link, in order to elucidate the suitability of the path-common weight generation method in high-elevation antenna environments such as cellular systems with a macrocell configuration. Laboratory experiments using multipath fading simulators and RF phase shifters elucidate that even when the ratio of the target Eb/I0 of the desired to interfering users is Δ Eb/I0=-12 dB, the increase in the average transmit Eb/N0 employing the CAAAD receiver coupled with fast transmission power control (TPC) using outer-loop control from that for Δ Eb/I0=0 dB is within only 1.0 dB owing to the accurate beam and null steering associated with fast TPC. Furthermore, field experiments demonstrate that the required transmission power at the average block error rate (BLER) of 10-2 employing the CAAAD receiver with four antennas is reduced by more than 2 dB compared to that using a four-branch space diversity receiver using maximum ratio combining (MRC) with the fading correlation between antennas of 0 when Δ Eb/I0=-15 dB and that the loss in the required transmission power of the CAAAD receiver in the same situation as that in a single-user environment is approximately 1 dB. The field experimental results in an actual propagation environment suggest that the CAAAD receiver is effective in suppressing multiple access interference, thus decreasing the required transmission power when the gap in the direction of arrival between the desired user and interfering users is greater than approximately 20 degrees.