Cell search is the process of identifying and obtaining downlink synchronization to cells so the broadcast information from the cell can be detected. This procedure is used both at initial access and at handover.
In order to perform cell search both in FDD, UE has to perform the following 5 steps.
1. Measure Reference Signals
2. Read System Information
3. Find Primary Synchronization Signal (P-SS) and Secondary Synchronization Signal (S-SS)
4. Get Synchronized
5. Cell Search Completed
The synchronization signals are shown in the figure below.