Experimental Evaluation of Coherent Adaptive Antenna Array Diversity Receiver Employing Optical Fiber Interface in IF Stage

Taisuke IHARA  Hidekazu TAOKA  Kenichi HIGUCHI  Mamoru SAWAHASHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E86-A   No.7   pp.1676-1688
Publication Date: 2003/07/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Multi-dimensional Mobile Information Networks)
optical fiber feeder,  adaptive antenna array,  interference suppression,  W-CDMA,  

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This paper investigates based on laboratory experiments the multiuser interference suppression effect of the coherent adaptive antenna array diversity (CAAAD) receiver employing an optical fiber feeder in the intermediate frequency (IF) stage, aiming at the practical use of adaptive antenna array beam forming techniques based on the W-CDMA air interface. We employed a configuration in which the optical fiber conversion, i.e., electrical-to-optical (E/O) conversion (vice versa (O/E)), is performed on a received signal amplified by an automatic gain control (AGC) amplifier in the IF stage, to abate the impact of the noise component generated by the E/O (O/E) converters. We first show by computer simulation the superiority of the optical fiber conversion in the IF stage to that in the radio frequency (RF) stage based on the achievable bit error rate (BER) performance. Furthermore, experimental results elucidate that the loss in the required transmit signal energy per bit-to-background noise power spectrum density ratio (Eb/N0) of the implemented CAAAD receiver at the average BER of 10-3 employing the optical fiber feeders in the IF stage compared to that with coaxial cables is within a mere 0.2 dB (six antennas, three users, two-path Rayleigh fading channel model, and the ratio of the target signal energy per bit-to-interference power spectrum density ratio (Eb/I0) of the desired user to that of the interfering users for fast transmission power control (TPC) is ΔEb/I0=-15 dB).