Method for detecting PCI collisions

1. A computer implemented method of operating a base station of a wireless communication network, wherein the method comprises:

comparing a number of missing context release messages with a first criterion;

comparing the error rate of connection reestablishment messages with a second criterion;

executing a cell global identity search algorithm if at least one of the first and the second criterion is fulfilled, wherein the cell global identity of at least one cell with the physical cell identity of the cell where the criterion was fulfilled is requested via an automatic neighbour relation measurement, and wherein a conflict of physical cell identities is detected and reported to an information algorithm when for the physical cell identity at least two cell global identities are found;

informing, via the information algorithm, a central network element and/or at least one base station of the mobile communication network about a conflict of physical cell identities when a conflict of physical cell identities is reported to the information algorithm; and

initiating a reassignment of at least one physical cell identity.

2. The method of claim 1 , further comprising:

receiving the physical cell identities and the cell global identities of the cells served by neighbouring base stations at a base station;

reporting the physical cell identities and the cell global identities of the cells served by the base station to at least one neighbouring base station of the wireless communication network;

determining if detailed cell information is required when two different cells with two different cell global identities have the same physical cell identity;

reporting a conflict of physical cell identities to the information algorithm, if no detailed cell information is required;

asking for the detailed cell information, if detailed cell information is required, by sending a message to the base station serving the cell if that detailed cell information is required;

determining based on the detailed cell information, if the cell global identity search algorithm is executed; and

executing the cell global identity search algorithm, if the physical cell identity conflict exists.

3. The method of claim 1 , wherein the method further comprises detecting the loss of connections between the base station and a plurality of mobile devices, whereby a loss of connection is detected when no uplink data is received without an initiated handover to a neighbouring base station of the wireless communication network, and wherein a physical cell identity conflict is reported to the information algorithm by the base station when the number of lost connections fulfills a third criterion.

4. The method of claim 1 , wherein the method further comprises requesting an automatic neighbour relation measurement, wherein a physical cell identity conflict is reported to the information algorithm by the base station when the same physical cell identity is assigned to two cells with different cell global identities.

5. The method of claim 1 , wherein the reassignment of at least one physical cell identity is initiated by the central network element.

6. The method of claim 1 , wherein reassignment of at least one physical cell identity is initiated by the base station.

7. The method of claim 1 , wherein the base station requests detailed cell information of at least one different base station.

8. The method of claim 1 , wherein the base station sends detailed cell information to at least one different base station that has requested the detailed cell information.

9. The method of claim 1 , wherein the first criterion is a first threshold of missing context release messages per a time interval.

10. The method of claim 1 , wherein the second criterion is a second threshold of the error rate of connection reestablishment messages.

11. The method of claim 1 , wherein the third criterion is a fourth threshold of the number of lost connections between the base station and the plurality of mobile devices.

12. The method of claim 1 , wherein the central network element is an operation and maintenance node.

13. The method of claim 1 , wherein the detailed cell information is information of the size and the position of the cell in terms of coverage area and main antenna lobe orientation.

14. A method implemented by a non-transitory computer readable storage medium, in which a program is saved, the program comprising instructions which, when they are executed in a programmable device, perform the method, the method comprising:

comparing a number of missing context release messages with a first criterion;

comparing the error rate of connection reestablishment messages with a second criterion;

executing a cell global identity search algorithm if at least one of the first and the second criterion is fulfilled, wherein the cell global identity of at least one cell with the physical cell identity of the cell where the criterion was fulfilled is requested via an automatic neighbour relation measurement, and wherein a conflict of physical cell identities is detected and reported to an information algorithm when for the physical cell identity at least two cell global identities are found;

informing, via the information algorithm, a central network element and/or at least one base station of the mobile communication network about a conflict of physical cell identities when a conflict of physical cell identities is reported to the information algorithm; and

initiating a reassignment of at least one physical cell identity.

15. A base station apparatus of a wireless communication network, the apparatus comprising at least one processor configured to:

compare a number of missing context release messages with a first criterion;

compare the error rate of connection reestablishment messages with a second criterion;

execute a cell global identity search algorithm if at least one of the first and the second criterion is fulfilled, wherein the cell global identity of at least one cell with the physical cell identity of the cell where the criterion was fulfilled is requested via an automatic neighbour relation measurement, and wherein a conflict of physical cell identities is detected and reported to an information algorithm when for the physical cell identity at least two cell global identities are found;

inform, via the information algorithm, a central network element and/or at least one base station of the mobile communication network about a conflict of physical cell identities when a conflict of physical cell identities is reported to the information algorithm; and

initiate a reassignment of at least one physical cell identity.

16. The method of claim 14 , the method further comprising:

receiving the physical cell identities and the cell global identities of the cells served by neighbouring base stations at a base station;

reporting the physical cell identities and the cell global identities of the cells served by the base station to at least one neighbouring base station of the wireless communication network;

determining if detailed cell information is required when two different cells with two different cell global identities have the same physical cell identity;

reporting a conflict of physical cell identities to the information algorithm, if no detailed cell information is required;

asking for the detailed cell information, if detailed cell information is required, by sending a message to the base station serving the cell if that detailed cell information is required;

determining based on the detailed cell information, if the cell global identity search algorithm is executed; and

executing the cell global identity search algorithm, if the physical cell identity conflict exists.

17. The method of claim 16 , wherein the method further comprises detecting the loss of connections between the base station and a plurality of mobile devices, whereby a loss of connection is detected when no uplink data is received without an initiated handover to a neighbouring base station of the wireless communication network, and wherein a physical cell identity conflict is reported to the information algorithm by the base station when the number of lost connections fulfills a third criterion.

18. The apparatus of claim 15 , the at least one processor of the apparatus being further configured to:

receive the physical cell identities and the cell global identities of the cells served by neighbouring base stations at a base station;

report the physical cell identities and the cell global identities of the cells served by the base station to at least one neighbouring base station of the wireless communication network;

determine if detailed cell information is required when two different cells with two different cell global identities have the same physical cell identity;

report a conflict of physical cell identities to the information algorithm, if no detailed cell information is required;

ask for the detailed cell information, if detailed cell information is required, by sending a message to the base station serving the cell if that detailed cell information is required;

determine based on the detailed cell information, if the cell global identity search algorithm is executed; and

execute the cell global identity search algorithm, if the physical cell identity conflict exists.

19. The apparatus of claim 18 , wherein the at least one processor of the apparatus is further configured to detect the loss of connections between the base station and a plurality of mobile devices, whereby a loss of connection is detected when no uplink data is received without an initiated handover to a neighbouring base station of the wireless communication network, and wherein a physical cell identity conflict is reported to the information algorithm by the base station when the number of lost connections fulfills a third criterion.

20. The apparatus of claim 19 , wherein the at least one processor of the apparatus is further configured to request an automatic neighbour relation measurement, wherein a physical cell identity conflict is reported to the information algorithm by the base station when the same physical cell identity is assigned to two cells with different cell global identities.