Pilot Symbol-Assisted Decision-Directed Coherent Adaptive Array Diversity for DS-CDMA Mobile Radio Reverse Link

Shinya TANAKA  Mamoru SAWAHASHI  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E80-A    No.12    pp.2445-2454
Publication Date: 1997/12/25
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Spread Spectrum Techniques and Applications)
adaptive antenna array,  DS-CDMA,  mobile radio,  

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Pilot symbol-assisted (PSA) decision-directed coherent adaptive array diversity (CAAD) is proposed for increasing the reverse link capacity of DS-CDMA mobile radio systems. In the proposed scheme, PSA channel estimation is applied to coherent Rake combining, and the weights of the antenna array are adaptively updated using both pilot symbols and decision-directed data symbols after Rake combining as references for minimum mean squared error (MMSE) criteria. The reverse link capacity of a 3-sectored base station is evaluated by computer simulation when fast transmit power control (TPC) based on singal-to-interference plus backgound noise power ratio (SIR) measurement is applied under nultipath Rayleigh fading environments. It is shown that a 6-element (sector) CAAD receiver can increase the capacity to about 4.2 times that with a single antenna (per sector) receiver when links are interference-limited. The link capacity achievable with the 6-element CAAD receiver is 1.2 times that with a 6-branch antenna diversity reciever with antenna spacing of 10 carrier wavelengths, while significantly reducing the strong interference from high bit rate transmission (high transmit power) users.