Synchronization of moving relay nodes and terminals in cellular networks

1. A method comprising:

at a base station, recognizing that a change of a prior configuration of the base station to a new configuration is forthcoming, wherein the prior configuration and the new configuration include a physical cell identifier;

based on a potential delay of the forthcoming change of the physical cell identifier of the configuration, reconfiguring by the base station, of a synchronization failure value to change a time required to detect a synchronization failure at the user equipment served by the base station;

informing, by the base station, the user equipment due to the forthcoming change of the prior configuration before the prior configuration of the base station is changed to the new configuration, wherein the informing includes informing the user equipment of the reconfigured synchronization failure value to be used at the user equipment; and

providing, by the base station, to the user equipment being served by the base station a synchronization signal indicating the new configuration after the prior configuration of the base station is changed to the new configuration,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

2. The method according to claim 1 , wherein the

reconfiguring comprises increasing the synchronization failure value to change the time required to detect a synchronization failure at the user equipment before the prior configuration of the base station is changed to the new configuration, and the

informing further comprises informing the user equipment of the increased synchronization failure value, and

the method further comprises recovering a pre-reconfiguration synchronization failure value and informing the user equipment of the recovered pre-reconfiguration synchronization failure value after the prior configuration of the base station is changed to the new configuration.

3. The method according to claim 1 ,

wherein the reconfiguring comprises decreasing a radio link failure timer value before the prior configuration of the base station is changed to the new configuration, and

informing further comprises informing the user equipment of the decreased radio link failure timer value; and

the method further comprises recovering a pre-reconfiguration radio link failure timer value and informing the user equipment of the recovered pre-reconfiguration radio link failure timer value after the prior configuration of the base station is changed to the new configuration.

4. The method according to claim 1 , further comprising

evaluating whether the user equipment or multiple user equipment served by the base station is of a legacy or a non-legacy type; and

selecting a way of informing the user equipment based on the evaluation.

5. The method according to claim 1 , further comprising

detecting a physical cell identifier collision between the prior configuration of the base station and at least one other base station, or receiving from the user equipment served by the base station, a report on a physical cell identifier collision between the prior configuration of the base station and at least one other base station, said report including evolved cell configurations of the base station and the other base station;

making a decision on the change of the prior configuration of the base station or the other base station; and

performing the informing and the providing when recognizing the decision on the change of the prior configuration of the base station to the new configuration.

6. A method comprising

at a user equipment, receiving information due to a forthcoming change of a prior configuration of a base station to a new configuration, wherein the information includes a reconfigured synchronization failure value to change a time required by the user equipment to detect a synchronization failure, wherein the prior configuration and the new configuration include a physical cell identifier;

applying the reconfigured synchronization failure value for the synchronization failure detection; and

receiving a provision of a synchronization signal indicating the new configuration of the base station,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

7. The method according to claim 6 , further comprising

storing, upon receipt of the information, a mapping between the prior configuration and the new configuration of the base station;

checking, upon receipt of the synchronization signal, whether a mapping between the prior configuration and the new configuration indicated in the synchronization signal corresponds to the stored mapping between the prior configuration and the new configuration; and

performing, if the mapping between the prior configuration and the new configuration indicated in the synchronization signal corresponds to the previously stored mapping between the prior configuration and the new configuration, updating the prior configuration with the new configuration based on the stored mapping, or

performing, if the mapping between the prior configuration and the new configuration indicated in the synchronization signal does not correspond to the stored mapping between the prior configuration and the new configuration, a cell measurement and reselection process using the new configuration indicated in the synchronization signal.

8. The method according to claim 7 , further comprising

receiving, in the information, the reconfigured synchronization failure value to change the time required to detect a synchronization failure; and

applying the received synchronization failure value for synchronization failure detection before receiving a different synchronization failure value from the base station.

9. The method according to claim 6 , further comprising

detecting a physical cell identifier collision between the prior configuration of the base station and at least one other base station; and

sending a report on the detected collision to the base station, said report including evolved cell configurations of the base station and the other base station.

10. An apparatus comprising:

an interface configured to communicate with at least one user equipment, and

a processor,

a memory comprising computer program code,

the memory and the computer program code configured, with the processor, to cause a base station at least to:

recognize that a change of a prior configuration of the base station to a new configuration is forthcoming, wherein the prior configuration and the new configuration include a physical cell identifier;

based on a delay of the change of the physical cell identifier of the new configuration, reconfigure a synchronization failure value to change a time required to detect a synchronization failure at a user equipment of the at least one user equipment served by the base station;

inform, via the interface, the user equipment due to the forthcoming change of the prior configuration before the prior configuration of the base station is changed to, the new configuration, wherein the informing includes informing the user equipment of the reconfigured synchronization failure value to be used by the user equipment; and

provide, via the interface, the user equipment being served by the base station with a synchronization signal indicating the new configuration after the prior configuration of the base station is changed to the new configuration,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

11. The apparatus according to claim 10 , wherein the reconfiguring comprises increasing the synchronization failure value to change the time required to detect a synchronization failure at the user equipment before the prior configuration of the base station is changed to the new configuration, and

the informing comprises to inform, via the interface, the user equipment of the increased synchronization failure value, and

the memory and the computer program code are further configured, with the processor, to cause the apparatus to recover a pre-reconfiguration synchronization failure value and inform, via the interface, the recovered pre-reconfiguration synchronization failure value after the prior configuration of the base station is changed to the new configuration.

12. The apparatus according to claim 10 , wherein

the reconfiguring further comprises decreasing a radio link failure timer value before the prior configuration of the base station is changed to the new configuration,

the informing further comprises informing, via the interface, to the user equipment the decreased radio link failure timer value, and

wherein the memory and the computer program code are further configured, with the processor, to cause the apparatus to recover a pre-reconfiguration radio link failure timer value and inform the user equipment of the recovered pre-reconfiguration radio link failure timer value after the prior configuration of the base station is changed to the new configuration.

13. The apparatus according to claim 10 , wherein the memory and the computer program code are further configured, with the processor, to cause the apparatus to:

evaluate whether the user equipment or multiple user equipment served by the base station is of a legacy or a non-legacy type; and

select a way of informing the user equipment based on the evaluation.

14. The apparatus according to claim 10 , wherein the memory and the computer program code are further configured, with the processor, to cause the apparatus to:

detect a physical cell identifier collision between the prior configuration of the base station and at least one other base station, or

receive, via the interface, from a user equipment served by the base station, a report on a physical cell identifier collision between the prior configuration of the base station and at least one other base station, said report including evolved cell configurations of the base station and the other base station,

make a decision on the change of the prior configuration of the base station or the other base station to the new configuration, and

perform the informing and the providing when recognizing the decision on the change of the prior configuration of the base station to the new configuration.

15. An apparatus comprising

an interface configured to communicate with a base station, and

a processor,

a memory comprising computer program code,

the memory and the computer program code configured, with the processor, to cause the apparatus to:

receive at a user equipment served by the base station, via the interface, information due to a forthcoming change of a prior configuration of the base station to a new configuration, wherein the information includes a reconfigured synchronization failure value to change a time required to detect a synchronization failure at the user equipment, wherein the prior configuration and the new configuration include a physical cell identifier to be used at the user equipment;

apply the reconfigured synchronization failure value far the synchronization failure detection; and

receive, via the interface, a synchronization signal indicating the new configuration of the base station,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

16. The apparatus according to claim 15 , wherein the memory and the computer program code are further configured, with the processor, to cause the apparatus to:

store, in a storage, upon receipt of the information, a mapping between the prior configuration and the new configuration of the base station;

check, upon receipt of the synchronization signal, whether a mapping between the prior configuration and the new configuration indicated in the synchronization signal corresponds to the stored mapping between the prior configuration and the new configuration; and

perform, if the mapping between the prior configuration and the new configuration indicated in the synchronisation signal corresponds to the stored mapping between the prior configuration and the new configuration, updating the prior configuration with the new configuration based on the stored mapping, or

perform, if the mapping between the prior configuration and the new configuration indicated in the synchronization signal does not correspond to the stored mapping between the prior configuration and the new configuration, a cell measurement and reselection process using the new configuration indicated in the synchronization signal.

17. The apparatus according to claim 16 , wherein the memory and the computer program code configured, with the processor, to cause the apparatus to:

receive, via the interface, in the information, the reconfigured synchronization failure value to change the time required to detect a synchronization failure; and

apply the received reconfigured synchronization failure value for synchronization failure detection before receiving a different synchronization failure value from the base station.

18. The apparatus according to claim 15 , wherein the memory and the computer program code configured, with the processor, to cause the apparatus to:

detect a physical cell identifier collision between the prior configuration of the base station and at least one other base station; and

send, via the interface, a report on the detected collision to the base station, said report including evolved cell configurations of the base station and the other base station.

19. A computer program product including a non-transitory computer-readable medium comprising software code portions being arranged, when run on a processor of an apparatus, to cause the apparatus to perform:

recognizing that a change of a prior configuration of a base station to a new configuration is forthcoming, wherein the prior configuration and the new configuration include a physical cell identifier;

based on a potential delay of the forthcoming change of the physical cell identifier of the configuration, reconfiguring a synchronization failure value to change a time required to detect a synchronization failure at a user equipment served by the base station;

informing the user equipment due to the forthcoming change of the prior configuration before the prior configuration of the base station is changed to the new configuration, wherein the informing includes informing the user equipment of the reconfigured synchronization failure value; and

providing the user equipment being served by the base station with a synchronization signal indicating the new configuration after the prior configuration of the base station is changed to the new configuration,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

20. A computer program product including a non-transitory computer-readable medium comprising software code portions being arranged, when run on a processor of an apparatus, to cause the apparatus to perform:

receiving an information due to a forthcoming change of a prior configuration of a base station to a new configuration, wherein the information includes a reconfigured synchronization failure value to change a time required at a user equipment served by the base station to detect a synchronization failure wherein the prior configuration and the new configuration include a physical cell identifier;

applying at least one of the reconfigured synchronization failure value for the synchronization failure detection; and

receiving a provision of a synchronisation signal indicating the new configuration of the base station,

wherein the synchronization failure value that was in use before the reconfiguring is recovered in response to the new configuration being active.

21. The method according to claim 1 , wherein providing the user equipment being served by the base station with the synchronization signal indicating the new configuration is using a dedicated information element in a system information update to the user equipment.

22. The method according to claim 1 , wherein the user equipment is a non-legacy user equipment, and wherein the reconfiguring comprises, based on the user equipment being a non-legacy user equipment, increasing a radio link failure timer value before the configuration of the base station.