Experiments on Inter-Sector Diversity Using Maximal Ratio Combining in W-CDMA Reverse Link

Akihito MORIMOTO  Kenichi HIGUCHI  Satoru FUKUMOTO  Mamoru SAWAHASHI  Fumiyuki ADACHI  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A    No.12    pp.3012-3025
Publication Date: 2001/12/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Spread Spectrum Techniques and Applications)
W-CDMA,  site diversity,  transmit power control,  Rake combining,  

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This paper evaluates the effect of inter-sector diversity with maximal ratio combining (MRC) coupled with coherent Rake combining and 2-branch antenna diversity reception in the transmit-power-controlled wideband direct sequence code division multiple access (W-CDMA) reverse link. We first elucidate based on laboratory experiments that the required average transmit signal energy per bit-to-background noise spectrum density ratio (Eb/N0) at the average bit error rate (BER) of 10-3 with inter-sector diversity using two sectors is decreased by approximately 1.4, 1.0, and 0.2 dB compared to that with inter-cell site diversity using two cell sites with antenna diversity reception due to the superiority of MRC to selection combining (SC), when the difference in the average path loss between a base station (BS) and a mobile station (MS) is Δ12 = 0, 3, and 6 dB, respectively. We also clarify in actual field experiments that the inter-sector diversity associated with Rake time diversity and antenna diversity further decreases the required average transmit power of a MS if the number of resolved paths is small such as 1 or 2 in each sector reception, even when the fading correlation between sectors is relatively large. Furthermore, we show that the required average transmit power of a MS for satisfying the average BER of 10-3 with inter-sector diversity is decreased above approximately 2.0-2.5 dB compared to that with one-sector reception, owing to the significantly increased inter-sector diversity effect in addition to the Rake time diversity and antenna diversity, when the fading correlation averaged over the measurement course is approximately 0.7.