How Synchronization Channel Works in LTE?

• the UE category and capability.
• the preferred PLMN.
  the carriers.

• The frame synchronization to be able to decode the DL radio frame.
• The cell parameters to be able request a connection.

• The PSS: Primary Synchronization Signal.
• The SSS: Secondary Synchronization Signal.
• The BCH, the broadcast channel.

The synchronization signals provide the cell id to the UE.
LTE supports 510 different cell identities.

• They are divided into 170 cell id groups and there are 3 cell ids per group.
• Cell id = 3* Cell_Group_id(0 to 169 Provided by the SSS) + Cell_id_in_group(0 to 2 Provided by the PSS )

The Primary Synchronization Signal (PSS):

• is used for the slot synchronization.
• is on the last OFDM symbol of slots 0 & 10 in the 1st & 6th sub-frames of each frame.
• carries one of the 3 cell id in group sequence.

The Secondary Synchronization Signal (SSS):

• is used for the frame synchronization.
• is on the same slot as PSS.
• is on the next to last OFDM symbol of slots 0 & 10 in the 1st & 6th sub-frames of each frame.
• carries one of the 170 unique cell group identifiers.

The PSS, the SSS and the BCH are carried over 6 Resource Blocks (RB) whatever the bandwidth
6 RBs = 6 * 12 Sub-ca = 72 Sub-carriers

By this way, these signals are independent from the bandwidth and can decode this signal without knowing it.