Physical cell id (PCI) is used for physical layer procedure. UE uses it to decode PSS and SSS. PCI range from 0 to 503. This is similar to scrambling code in UMTS
physical CellID=PSS+3*SSS. As PSS is between 0 to 2 and SSS 0 to 167
PCI is trasmitted in MIB
Ex: 2014 Dec 24 15:29:46.026 [00] 0xB0C1 LTE RRC MIB Message Log Packet
Version = 1
Physical cell ID = 45
FREQ = 2130
SFN = 568
Number of TX Antennas = 2
DL Bandwidth = 10 MHz (50)
Cell ID uniquely identifies eNB within network. UE uses this for identifying a cell whereas core network uses this for OAM.
It is transmitted in SIB1
e.g
message c1 : systemInformationBlockType1 :
{
cellIdentity '00000000 00000000 11100101 1010'B,
}