Method and apparatus for relaxing RRM measurement in wireless communication system

1. A method of relaxing frequency measurement by a terminal in a wireless communication system, the method comprising:

receiving, from a base station, system information including first configuration information on frequency measurement and second configuration information on relaxed frequency measurement, the second configuration information including information on a not at cell edge criterion; and

determining whether to perform frequency measurement based on the not at cell edge criterion,

wherein the first configuration information includes S IntraSearchP for a cell selection receive level value (Srxlev) for an intra-frequency, S IntraSearchQ for a cell selection quality value (Squal) for the intra-frequency, S nonIntraSearchP for the Srxlev for an inter-frequency or an inter-radio access technology (inter-RAT) frequency, and S nonIntraSearchQ for the Squal for the inter-frequency or the inter-RAT frequency, and

wherein the information on the not at cell edge criterion includes S SearchThresholdP for the Srxlev for relaxed frequency measurement which is less than or equal to both the S IntraSearchP and the S nonIntraSearchP , and S SearchThresholdQ for the Squal for relaxed frequency measurement which is less than or equal to both the S IntraSearchQ and the S nonIntraSearchQ .

2. The method of claim 1 , further comprising:

determining whether to perform frequency measurement further based on a low mobility criterion,

wherein the second configuration information further includes other information on the low mobility criterion including S SearchDeltaP for variation of the Srxlev and information of an evaluation time period T SearchDeltaP .

3. The method of claim 2 , wherein the determining whether to perform frequency measurement comprises determining not to perform frequency measurement for intra-frequency, new radio (NR) inter-frequencies configured with equal or lower priority than a frequency of a serving cell of the terminal, and inter-RAT frequencies configured with equal or lower priority than the frequency of a serving cell of the terminal, in case that the low mobility criterion is fulfilled for the time period T SearchDeltaP and the not at cell edge criterion is fulfilled.

4. The method of claim 2 , wherein the determining whether to perform frequency measurement comprises determining not to perform frequency measurement for new radio (NR) inter-frequencies and inter-RAT frequencies configured with higher priority than a frequency of a serving cell of the terminal, in case that the low mobility criterion is fulfilled for the time period T SearchDeltaP , and the not at cell edge criterion is fulfilled.

5. The method of claim 2 , wherein the determining whether to perform frequency measurement comprises determining not to perform frequency measurement for new radio (NR) inter-frequencies and inter-RAT frequencies configured with higher priority than a frequency of a serving cell of the terminal, in case that the following conditions are satisfied:

an Srxlev of the serving cell of the terminal is greater than the S nonIntraSearchP and an Squal of the serving cell is greater than the S nonIntraSearchQ , the low mobility criterion is fulfilled, and

a highPriorityMeasRelax indicating whether a measurement for a high priority frequency can be relaxed is configured by the second configuration information.

6. The method of claim 2 ,

wherein the low mobility criterion includes a value obtained by subtracting an Srxlev of a serving cell of the terminal from a reference Srxlev (Srxlev Ref ) of the serving cell is less than the S SearchDeltaP , and

wherein a current Srxlev of the serving cell is determined as the Srxlev Ref of the serving cell in case that the terminal selects or reselects a new cell, the current Srxlev of the serving cell is greater than a current Srxlev Ref of the serving cell, or at least one of the low mobility criterion or the not at cell edge criterion is not fulfilled for the time period T SearchDeltaP .

7. The method of claim 1 , wherein the not at cell edge criterion includes an Srxlev of a serving cell of the terminal being greater than the S SearchThresholdP and in case that the S SearchThresholdQ is included in the information on the not at cell edge criterion, an Squal of the serving cell is greater than the S SearchThresholdQ .

8. A terminal relaxing frequency measurement in a wireless communication system, the terminal comprising:

a transceiver; and

at least one processor operably coupled with the transceiver and configured to:

receive, from a base station, system information including first configuration information on frequency measurement and second configuration information on relaxed frequency measurement, the second configuration information including information on a not at cell edge criterion, and

determine whether to perform frequency measurement based on the not at cell edge criterion,

wherein the first configuration information includes S IntraSearchP for a cell selection receive level value (Srxlev) for an intra-frequency, S IntraSearchQ for a cell selection quality value (Squal) for the intra-frequency, S nonIntraSearchP for the Srxlev for an inter-frequency or an inter-radio access technology (inter-RAT) frequency, and S nonIntraSearchQ for the Squal for the inter-frequency or the inter-RAT frequency, and

wherein the information on the not at cell edge criterion includes S SearchThresholdP for the Srxlev for relaxed frequency measurement which is less than or equal to both the S IntraSearchP and the S nonIntraSearchP , and S SearchThresholdQ for the Squal for relaxed frequency measurement which is less than or equal to both the S IntraSearchQ and the S nonIntraSearchQ .

9. The terminal of claim 8 , wherein the at least one processor is further configured to determine whether to perform frequency measurement further based on a low mobility criterion,

wherein the second configuration information further includes other information on the low mobility criterion including S SearchDeltaP for variation of the Srxlev and information of an evaluation time period T SearchDeltaP .

10. The terminal of claim 9 , wherein the at least one processor is further configured to determine not to perform frequency measurement for intra-frequency, new radio (NR) inter-frequencies configured with equal or lower priority than a frequency of a serving cell of the terminal, and inter-RAT frequencies configured with equal or lower priority than the frequency of a serving cell of the terminal, in case that the low mobility criterion is fulfilled for the time period T SearchDeltaP and the not at cell edge criterion is fulfilled.

11. The terminal of claim 9 , wherein the at least one processor is further configured to determine not to perform frequency measurement for new radio (NR) inter-frequencies and inter-RAT frequencies configured with higher priority than a frequency of a serving cell of the terminal, in case that the low mobility criterion is fulfilled for the time period T SearchDeltaP , and the not at cell edge criterion is fulfilled.

12. The terminal of claim 9 , wherein the at least one processor is further configured to determine not to perform frequency measurement for new radio (NR) inter-frequencies and inter-RAT frequencies configured with higher priority than a frequency of a serving cell of the terminal, in case that the following conditions are satisfied:

an Srxlev of the serving cell of the terminal is greater than the S nonIntraSearchP and an Squal of the serving cell is greater than the S nonIntraSearchQ ,

the low mobility criterion is fulfilled, and

a highPriorityMeasRelax indicating whether a measurement for a high priority frequency can be relaxed is configured by the second configuration information.

13. The terminal of claim 9 ,

wherein the low mobility criterion includes a value obtained by subtracting an Srxlev of a serving cell of the terminal from a reference Srxlev (Srxlev Ref ) of the serving cell is less than the S SearchDeltaP , and

wherein a current Srxlev of the serving cell is determined as the Srxlev Ref of the serving cell in case that the terminal selects or reselects a new cell, the current Srxlev of the serving cell is greater than a current Srxlev Ref of the serving cell, or at least one of the low mobility criterion or the not at cell edge criterion is not fulfilled for the time period T SearchDeltaP .

14. The terminal of claim 8 , wherein the not at cell edge criterion includes an Srxlev of a serving cell of the terminal being greater than the S SearchThresholdP and in case that the S SearchThresholdQ is included in the information on the not at cell edge criterion, an Squal of the serving cell is greater than the S SearchThresholdQ .

15. A computer program product comprising a non-transitory computer readable storage medium having a computer readable program stored therein,

wherein the computer readable program, when executed on a computing device, causes the computing device to:

receive, from a base station, system information including first configuration information on frequency measurement and second configuration information on relaxed frequency measurement, the second configuration information including information on a not at cell edge criterion, and

determine whether to perform frequency measurement based on the not at cell edge criterion,

wherein the first configuration information includes S IntraSearchP for a cell selection receive level value (Srxlev) for an intra-frequency, S IntraSearchQ for a cell selection quality value (Squal) for the intra-frequency, S nonIntraSearchP for the Srxlev for an inter-frequency or an inter-radio access technology (inter-RAT) frequency, and S nonIntraSearchQ for the Squal for the inter-frequency or the inter-RAT frequency, and

wherein the information on the not at cell edge criterion includes S SearchThresholdP for the Srxlev for relaxed frequency measurement which is less than or equal to both the S IntraSearchP and the S nonIntraSearchP , and S SearchThresholdQ for the Squal for relaxed frequency measurement which is less than or equal to both the S IntraSearchQ and the S nonIntraSearchQ .