Experiments on Inter-Cell Site Diversity Using Two-Step Selection Combining in W-CDMA Reverse Link

Akihito MORIMOTO  Kenichi HIGUCHI  Satoru FUKUMOTO  Mamoru SAWAHASHI  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Communications   Vol.E84-B    No.3    pp.435-445
Publication Date: 2001/03/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Innovative Mobile Communication Technologies at the Dawn of the 21st Century)
DS-CDMA,  site diversity,  transmit power control,  CRC,  SIR,  

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This paper proposes an inter-cell site diversity scheme based on 2-step selection combining (SC) and investigates through experimentation the effect of inter-cell site diversity in the transmit power-controlled wideband direct sequence code division multiple access (W-CDMA) reverse link. In the proposed algorithm, the decoded data sequence after soft-decision Viterbi decoding at each base station (BS) is transferred via the backhaul (wired line between BS and radio network controller (RNC) simulator) to the RNC simulator accompanied by reliability information of cyclic redundancy check (CRC) results per frame and the average signal-to-interference power ratio (SIR) calculated over the interleaving interval. The 2-step SC for each frame is performed at the RNC simulator using these two types of reliability information. We conclude from the laboratory experiments that the transmit power of a mobile station (MS) can be decreased since the selection period, TSEL, is shorter irrespective of the interleaving length, TILV, and that the required transmit power of a MS satisfying the average BER of 10-3 in inter-cell site diversity among 2 and 3 cell sites can be decreased by approximately 1.0 (0.5) dB and 1.3 (0.7) dB for fading maximum Doppler frequency fD = 5 (80) Hz, respectively, compared to a one-site connection (TILV = 80 msec, TSEL = 10 msec, path loss difference between 2 BSs and MS is 0 dB). We also confirmed by field experiments that the required transmit power of a MS in inter-cell site diversity between 2 cell sites can be decreased by approximately 2.0 dB compared to that of a one-site connection.