Experimental Evaluation of Coherent Rake Combining for Broadband Single-Carrier DS-CDMA Wireless Communications

Takehiro IKEDA  Koichi OKAWA  Mamoru SAWAHASHI  Fumiyuki ADACHI  

Publication
IEICE TRANSACTIONS on Communications   Vol.E84-B   No.3   pp.415-424
Publication Date: 2001/03/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Innovative Mobile Communication Technologies at the Dawn of the 21st Century)
Category: 
Keyword: 
wireless communication,  broadband DS-CDMA,  Rake combining,  transmit power control,  

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Summary: 
This paper experimentally evaluates the bit error rate (BER) performance of single-carrier broadband DS-CDMA (B-CDMA) scheme using a 100-MHz bandwidth (chip rate of 81.92 Mcps) in frequency-selective multipath fading channels. The achievable information bit rate is 20.36 (2.5) Mbps when the spreading factor (SF) is SF = 4 (32). In order to achieve a high data-rate transmission with high quality (i.e., average BER is below 10-6), we apply pilot symbol-assisted coherent Rake receiving with a large number of Rake fingers (maximum number of Rake fingers is SF2), 2-branch antenna diversity reception, convolutional coding, and signal-to-interference power ratio (SIR) measurement-based fast closed-loop transmit power control (TPC). Experimental results show that the average BER of 10-6 for the 20.36 (2.5)-Mbps transmission is achieved at the required average transmit Eb/N0 of approximately 6.7 (5.0) dB when the number of multipaths is L = 2 and the maximum fading Doppler frequency is fD = 20 Hz. We also show that Rake time diversity and fast TPC are effective in a broadband propagation channel where many resolvable paths (such as 12 paths) are observed.