Physical cell identifier collision detection

1. A base station for performing physical cell identifier (PCI) collision detection, comprising:

at least one processor configured to:

determine whether a PCI in a radio resource control (RRC) Re-establishment message is the same as a PCI used by a cell implemented by the base station;

determine whether a cell radio network temporary identifier (C-RNTI) in the RRC Re-establishment message is outside a reserved range of C-RNTIs for the cell; and

identify a possible PCI collision for the cell when:

the PCI in the RRC Re-establishment message is the same as the PCI used by the cell; and

the C-RNTI in the RRC Re-establishment message is outside the reserved range of C-RNTIs for the cell; and

when the possible PCI collision is identified for the cell, transmit an alarm message to a management system indicating the possible PCI collision for the cell.

2. The base station of claim 1 , wherein the at least one processor is configured to:

receive the RRC Re-establishment message from a user equipment (UE).

3. The base station of claim 1 , wherein the management system determines whether an actual PCI collision is detected in response to receiving the alarm message.

4. The base station of claim 1 , wherein an actual PCI collision is detected when the cell uses a same operating frequency as a neighboring cell associated with the PCI in the RRC Re-establishment message.

5. The base station of claim 1 , wherein the PCI for the cell is reconfigured in response to determining that an actual PCI collision is detected.

6. The base station of claim 1 , wherein the PCI for the cell is reconfigured by:

manual input from an operator at the management system; or

the at least one processor in the base station selecting a new PCI from a provisioned PCI list.

7. The base station of claim 1 , wherein the PCI remains in use by the cell when an actual PCI collision is not detected by the management system in response to receiving the alarm message.

8. The base station of claim 1 , wherein the base station is implemented using a cloud radio access network (C-RAN), comprising:

at least one radio point (RP), each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and

a baseband controller communicatively coupled to the at least one RP via a front-haul ETHERNET network.

9. The base station of claim 8 , wherein the at least one processor is implemented in the baseband controller.

10. The base station of claim 1 , wherein the base station is implemented using a cloud radio access network (C-RAN), comprising:

a plurality of remote units (RUs), each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and

a centralized unit communicatively coupled to the plurality of RUs via a fronthaul ETHERNET interface, wherein the centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3GPP Fifth Generation communication system.

11. The base station of claim 10 , wherein the at least one processor is implemented in the centralized unit.

12. The base station of claim 1 , wherein the base station is implemented using a macro base station.

13. A method for physical cell identifier (PCI) collision detection in a base station, the method comprising:

determining whether a PCI in a radio resource control (RRC) Re-establishment message is the same as a PCI used by a cell implemented by the base station;

determining whether a cell radio network temporary identifier (C-RNTI) in the RRC Re-establishment message is outside a reserved range of C-RNTIs for the cell; and

identifying a possible PCI collision for the cell when:

the PCI in the RRC Re-establishment message is the same as a PCI used by the cell; and

the C-RNTI in the RRC Re-establishment message is outside the reserved range of C-RNTIs for the cell; and

when the possible PCI collision is identified for the cell, transmitting an alarm message to a management system indicating the possible PCI collision for the cell.

14. The method of claim 13 , further comprising:

receiving the RRC Re-establishment message from a user equipment (UE).

15. The method of claim 13 , further comprising determining, at the management system, whether an actual PCI collision is detected in response to receiving the alarm message.

16. The method of claim 13 , further comprising detecting an actual PCI collision when the cell uses a same operating frequency as a neighboring cell associated with the PCI in the RRC Re-establishment message.

17. The method of claim 13 , further comprising reconfiguring the PCI for the cell in response to determining that an actual PCI collision is detected.

18. The method of claim 13 , wherein the PCI for the cell is reconfigured by:

manual input from an operator at the management system; or

the base station selecting a new PCI from a provisioned PCI list.

19. The method of claim 13 , wherein the PCI remains in use by the cell when an actual PCI collision is not detected by the management system in response to receiving the alarm message.

20. The method of claim 13 , wherein the base station is implemented using a cloud radio access network (C-RAN), comprising:

at least one radio point (RP), each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and

a baseband controller communicatively coupled to the at least one RP via a front-haul ETHERNET network.

21. The method of claim 20 , wherein the method is performed by the baseband controller.

22. The method of claim 13 , wherein the base station is implemented using a cloud radio access network (C-RAN), comprising:

a plurality of remote units (RUs), each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and

a centralized unit communicatively coupled to the plurality of RUs via a fronthaul ETHERNET interface, wherein the centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3GPP Fifth Generation communication system.

23. The method of claim 22 , wherein the method is performed by the centralized unit.

24. The method of claim 13 , wherein the base station is implemented using a macro base station.