Base Station Search at Cell Boundaries for Wideband-CDMA
Date Issued
2006
Date
2006
Author(s)
Wu, Tzung-Jin
DOI
en-US
Abstract
The third-generation (3G) cellular systems can provide higher data rate services with improved service quality and capacity. Among the 3G cellular systems, IS-2000 and Wideband Code-Division-Multiple-Access (W-CDMA) are based on direct-sequence code-division multiple-access (DS-CDMA) technology. In W-CDMA systems, synchronization among base stations is not necessary. Each cell is identi ed by its unique downlink primary scrambling code. The process of the mobile station searching for a cell and achieving code and time synchronization to its downlink scrambling code is referred to as cell search. Cell search is performed in three scenarios: initial cell search when a mobile station is switched on, idle mode search when inactive, and active mode search during a call. In W-CDMA, the cell search itself is divided into five acquisition stages: slot synchronization, frame synchronization and scrambling
code group identi cation, scrambling code identi cation, frequency acquisition, and cell identi cation.
In practical scenarios, a mobile station performs initial cell search in a multicell environment and receives many synchronization channels passed through a fading channel from di erent base stations. In this situation, di erent synchronization channels groups of di erent cells overlap in time and interfere with each other. This increases the di culty of performing cell search. In this thesis, a convenient multipath searching algorithm is proposed to nd a signal replica within a search window. Combining one more path improves the initial search performance and the average acquisition time. It is shown that the proposed approach has a performance improvement compared to the conventional methods.
Subjects
寬頻分碼多工
W-CDMA
Type
thesis