Small cell mobility enhancement

1. A method for mobility management between large and small cells, comprising: in a user equipment:

receiving different first and second procedures for measurement gaps to be applied based on radio access coverage at the user equipment within a predetermined time duration;

applying at least one procedure for inter-frequency measurements of at least one carrier, wherein the first procedure is applied using a first set of measurement gaps when a carrier having at least one cell deployed for providing non-continuous coverage radio access is to be measured and the second procedure is applied using a second set of measurement gaps when a carrier having at least one cell deployed for providing continuous coverage radio access is to be measured, wherein the inter-frequency measurements are performed less frequently in the first procedure than in the second procedure; and

performing the inter-frequency measurements according to the first procedure after receiving an indication from a network to perform the inter-frequency measurement according to the first procedure.

2. The method of claim 1 , further comprising:

obtaining information on whether the non-continuous coverage radio access is available in the current location or not; and

selecting the procedure of the inter-frequency measurement based on whether the non-continuous coverage radio access is available or not.

3. The method of claim 2 , further comprising:

receiving at least one of following:

a neighbor list containing information on the cells deployed for providing non-continuous coverage radio access in the current location, and

information on physical cell identifications assigned to the cells deployed for providing non-continuous coverage radio access.

4. The method of claim 1 , further comprising:

setting the procedure for the inter-frequency measurements on when the currently serving cell is overloaded or the signal quality and/or the signal power of the current serving cell decreases to a predetermined threshold level, wherein a higher predetermined threshold level is applied for the first procedure than for the second.

5. The method of claim 1 , further comprising:

having the first procedure on continuously.

6. The method of claim 1 , wherein, when discontinuous reception is off and the first procedure is on, a cycle which comprises the following is repetitively carried out:

performing predetermined number of time-separated inter-frequency measurements by applying gap-assisted inter-frequency measurements; and

restraining from performing inter-frequency measurements for a predetermined time duration exceeding the time-separation after the predetermined number of inter-frequency measurements have been done.

7. The method of claim 1 , further comprising, when discontinuous reception is on and the first procedure is on:

restraining from performing inter-frequency measurements in every predetermined discontinuous reception cycle.

8. The method of any of claim 1 , further comprising:

providing a measurement report indicating that the inter-frequency measurement corresponding to the measurement report has been performed for a carrier of a cell deployed for providing non-continuous coverage radio access.

9. The method of any of claim 1 , further comprising:

causing a transmission of a proximity indication or a request for a measurement gap configuration to measure the cell deployed for providing non-continuous coverage more accurately than an immediately previous measurement of the cell.

10. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into a user equipment, execute the method according to claim 1 .

11. A method for mobility management between large and small cells, comprising: in a base station that provides continuous coverage radio access:

providing first and second procedures for measurement gaps to be applied based on radio access coverage at a user equipment within a predetermined time duration such that measurement gaps of the first procedure are less frequent than measurement gaps of the second procedure;

sending an indication to a user equipment to trigger the user equipment to perform inter-frequency measurements according to the first procedure utilizing a first set of measurement gaps;

and at least one of the following:

a neighbor list containing information on the cells deployed for providing non-continuous coverage radio access in the current location of the user equipment,

information on physical cell identifications assigned to the cells deployed for providing non-continuous coverage radio access,

information about a carrier having at least one cell deployed for providing non-continuous coverage radio access, wherein the carrier is to be measured using the first set of measurement gaps when performing inter-frequency measurements, and

information about at least one carrier for which an inter-frequency measurement procedure should be applied which inter-frequency measurement procedure is different from the inter-frequency measurement procedure applied for other carriers.

12. The method of claim 11 , further comprising:

providing information of threshold levels for triggering the inter-frequency measurement procedure, wherein the threshold levels are separate for the first procedure and for the second procedure, wherein the first procedure is applied when a carrier having at least one cell deployed for providing non-continuous coverage radio access is to be measured and a second procedure is applied when a carrier having at least one cell deployed for providing continuous coverage radio access is to be measured.

13. A computer program product embodied on a distribution medium readable by a computer and comprising program instructions which, when loaded into a base station, execute the method according to claim 11 .

14. A user equipment for mobility management between large and small cells, comprising:

at least one processor and at least one memory including a computer program code, wherein the at least one memory and the computer pro-gram code are configured to, with the at least one processor, cause the user equipment at least to:

receive different first and second procedures for measurement gaps to be applied based on radio access coverage at the user equipment within a predetermined time duration;

apply at least one procedure for inter-frequency measurements of at least one carrier, wherein the first procedure is applied using a first set of measurement gaps when a carrier having at least one cell deployed for providing non-continuous coverage radio access is to be measured and the second procedure is applied using a second set of measurement gaps when a carrier having at least one cell deployed for providing continuous coverage radio access is to be measured, wherein the inter-frequency measurements are performed less frequently in the first procedure than in the second procedure; and

perform the inter-frequency measurements according to the first procedure after receiving an indication from a network to perform the inter frequency measurements according to the first procedure.

15. The user equipment of claim 14 , wherein the user equipment is further caused to:

obtain information on whether the non-continuous coverage radio access is available in the current location or not; and

select the procedure of the inter-frequency measurement based on whether the non-continuous coverage radio access is available or not.

16. The user equipment of claim 15 , wherein the user equipment is further caused to:

receive at least one of following:

a neighbor list containing information on the cells deployed for providing non-continuous coverage radio access in the current location, and

information on physical cell identifications assigned to the cells deployed for providing non-continuous coverage radio access.

17. The user equipment of claim 14 , wherein the user equipment is further caused to:

set the procedure for the inter-frequency measurements on when the currently serving cell is overloaded or the signal quality and/or the signal power of the current serving cell decreases to a predetermined threshold level, wherein a higher predetermined threshold level is applied for the first procedure than for the second.

18. The user equipment of claim 14 , wherein the user equipment is further caused to:

have the first procedure on continuously.

19. The user equipment of claim 14 , wherein, when discontinuous reception is off and the first procedure is on, the user equipment is further caused to repetitively carry out the following:

perform predetermined number of time-separated inter-frequency measurements by applying gap-assisted inter-frequency measurements; and

restrain from performing inter-frequency measurements for a predetermined time duration exceeding the time-separation after the predetermined number of inter-frequency measurements have been done.

20. The user equipment of claim 14 , wherein the user equipment is further caused to, when discontinuous reception is on and the first procedure is on:

restrain from performing inter-frequency measurements in every predetermined discontinuous reception cycle.

21. The user equipment of claim 14 , wherein the user equipment is further caused to:

provide a measurement report indicating that the inter-frequency measurement corresponding to the measurement report has been performed for a carrier of a cell deployed for providing non-continuous coverage radio access.

22. The user equipment of claim 14 , wherein the user equipment is further caused to:

transmit a proximity indication or a request for a measurement gap configuration to measure the cell deployed for providing non-continuous coverage more accurately than an immediately previous measurement of the cell.

23. A base station for mobility management between large and small cells, comprising:

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

provide first and second procedures for measurement gaps to be applied based on radio access coverage at a user equipment within a predetermined time duration such that measurement gaps of the first procedure are less frequent than the measurement gaps of the second procedure;

send an indication to a user equipment to trigger the user equipment to perform inter-frequency measurements according to the first procedure utilizing a first set of measurement gaps;

and at least one of the following:

a neighbor list containing information on the cells deployed for providing non-continuous coverage radio access in the current location of the user equipment,

information on physical cell identifications assigned to the cells deployed for providing non-continuous coverage radio access,

information about a carrier having at least one cell deployed for providing non-continuous coverage radio access, wherein the carrier is to be measured using the first set of measurement gaps when performing inter-frequency measurements, and

information about at least one carrier for which an inter-frequency measurement procedure should be applied which inter-frequency measurement procedure is different from the inter-frequency measurement procedure applied for other carriers.

24. The base station of claim 23 , wherein the base station is further caused to:

provide information of threshold levels for triggering the inter-frequency measurement procedure, wherein the threshold levels are separate for the first procedure and for the second procedure, wherein the first procedure is applied when a carrier having at least one cell deployed for providing non-continuous coverage radio access is to be measured and a second procedure is applied when a carrier having at least one cell deployed for providing continuous coverage radio access is to be measured.