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Experiments on Coherent Multicode DS-CDMA
Tomohiro DOHI Yukihiko OKUMURA Akihiro HIGASHI Koji OHNO Fumiyuki ADACHI
IEICE TRANSACTIONS on Communications
Publication Date: 1996/09/25
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Personal Communications)
Category: CDMA and multiple access technologies
DS-CDMA, pilot symbol-aided coherent RAKE, interference power measurement based power control, orthogonal multicode transmission, test-bed, field test,
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Direct sequence code division multiple access (DS-CDMA) is a promising candidate for 3rd generation mobile communications systems. We recently proposed a coherent multicode DS-CDMA (CM-CDMA) scheme that uses pilot symbol-aided coherent RAKE, interference power measurement based transmit power control, orthogonal multicode transmission, and concatenated channel coding. We have implemented a CM-CDMA test-bed for a series of laboratory and field tests using the 2 GHz band. This paper describes the test-bed system and experimental results are presented. It is confirmed that pilot symbol-aided coherent RAKE can reduce the required signal energy per bit-to-interference plus background noise spectrum density ratio (Eb/Io) by 2-3 dB from that achievable with differential detection. Also shown is that by using both RAKE combining and SIR-based power control the transmit power of mobile stations can be significantly reduced. Measurement results show that the required Eb/Io degrades only slightly when 24 code-channels (768 kbps) are used since orthogonal Gold sequences are used as short spreading codes.