W-CDMA系統(tǒng)中輔同步信道捕獲的改進
An improved scheme for secondary synchronous channel acquisition in W-CDMA system
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摘要: W-CDMA系統(tǒng)中,各基站之間是異步時序關系。為了快速識別基站,3GPP協(xié)議引入了三步同步的小區(qū)搜索算法。第二步對輔同步信道的搜索是極其重要的。采用傳統(tǒng)的匹配濾波器組結構運算復雜度比較大。該文分析了輔同步信道的結構,根據其構造特性提出了部分快速哈達瑪變換(PFHT)的快速算法。理論分析證明該算法減少了接近70％的運算量。同時,針對輔同步信道的RS碼表搜索,提出了一種分布式子圖搜索算法,與窮舉搜索相比,大幅度降低了復雜度。經過這兩方面的改進,使輔同步信道捕獲的硬件設計復雜度大大降低,對于工程應用具有重要價值。Abstract: The timing relationship between base stations is asynchronous in W-CDMA sys-tem. So the three-step cell search algorithm is introduced in 3GPP protocols in order to identify the special base station quickly. The second step, Secondary Synchronous CHannel(S-SCH) ac-quisition, is much critical, but the computing complexity of the conventional matched filter bank method is very large. This paper proposes Partial Fast Hadamard Transform (PFHT) ac-cording to the S-SCH structural property, which extremely reduces the computing complexity to almost 70%. On the other hand, a distributed sub-graph search algorithm is put forward to save more complication than RS code table brute-force search. In a word, the hardware complexity is dramatically cut down by the improved scheme, which is valuable for engineering applications.
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3rd Generation Partnership Project, Spreading and modulation, 3GPP Tech. Spec., TS25.213,V3.3.0, June 2000.3rd Generation Partnership Project, Physical layer procedures(FDD), 3GPP Tech. Spec.,TS25.214, V3.3.0, June 2000.[2]K. Higuchi, M. Sawahashi, F. Adachi, Fast cell search algorithm using long code masking in DS-CDMA asynchronous cellular system, Tech. Rep. IEICE, Jan. 1997, 57-62.[3]K. Higuchi, M. Sawahashi, F. Adachi, Fast cell search algorithm in DS-CDMA mobile using long spreading codes, in Proc. IEEE 1997 Veh. Tech. Conf., Phoenix, AZ, May 1997, 1430 1434.[4]Y.-P. E. Wang, T. Ottosson, Cell search in W-CDMA, IEEE J. on Selected Areas in Communications, Aug. 2000, JSAC-18(7), 1470-1481. -
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