Cell Search Time Comparison Using Hierarchical and Non-hierarchical Synchronization Channels in OFDM Based Evolved UTRA Downlink

Satoshi NAGATA  Motohiro TANNO  Yoshihisa KISHIYAMA  Kenichi HIGUCHI  Mamoru SAWAHASHI  

IEICE TRANSACTIONS on Communications   Vol.E92-B    No.5    pp.1608-1618
Publication Date: 2009/05/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.1608
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Radio Access Techniques for 3G Evolution)
Evolved UTRA,  OFDM,  cell search,  synchronization channel,  

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This paper presents a comparison of hierarchical and non-hierarchical synchronization channel (SCH) structures in terms of the initial cell search time and neighboring cell search time in order to establish the optimum SCH structure in the Evolved UTRA downlink. Computer simulation results show that in a 19-cell configuration, the cell search time at 90% in the cumulative distribution function (CDF) using the hierarchical SCH structure is less than half that using the non-hierarchical SCH structure in a neighboring cell search under low signal-to-interference plus noise power ratio (SINR) conditions, although both structures achieve almost the same cell search time in the initial cell search. This is due to the cross-correlation based SCH symbol timing detection in the hierarchical SCH structure, which is affected less by noise than the auto-correlation based detection in the non-hierarchical SCH structure. Thus, we conclude that the hierarchical SCH structure is superior to the non-hierarchical SCH structure based on the cell search time performance especially in the neighboring cell search.