LTE Cell search uses a hierarchical procedure. This is quite similar to WCDMA.
Base stations in LTE radio cell is identified by a Cell Identity (CI). There are a total of 504 physical layer CI’s. With hierarchical cell search approach 168 unique groups are created in physical layer. Each group consists of 3 unique physical layer cell identities.
Downlink cell search is always assumed to be transmitted from base-station towards mobile device.
Cell search primary synchronization signal or PSS - 3 unique physical CI’s
Cell search secondary synchronization signal or SSS - One of possible 168 physical cell identity groups.
This scheme of cell search is adopted from WCDMA. In WCDMA scrambling codes are used to uniquely identify base stations and cells.