METHODS FOR DERIVING PERIODIC RAN NOTIFICATION AREA (RNA) UPDATE TIMER (T380) FOR RRC-INACTIVE UES

1 . A method, performed by at least one processor, for configuring a periodic radio access network (RAN) notification area (RNA) update timer based on a periodic registration update timer, the method comprising:

obtaining a periodic registration update timer value provided by a core network; and

determining a RNA update timer value based on the obtained periodic registration update timer value such that the RNA update timer value is less than the obtained periodic registration update timer value and less than a predetermined maximum value for the RNA update timer.

2 . The method of claim 1 , wherein the determining the RNA update timer value comprises:

determining a parameter based on the periodic registration update timer; and

determining the RNA update timer value based on the parameter and the periodic registration update timer value.

3 . The method of claim 2 , wherein the determining the RNA update timer value further comprises configuring and/or updating the parameter via an O1 interface between a Service Management and Orchestration (SMO) framework and a centralized unit of a radio access network (RAN).

4 . The method of claim 2 , wherein:

the determining the parameter comprises:

receiving, by an xApp of a near-real-time RAN Intelligent Controller (RIC), the periodic registration update timer value; and

determining, by the xApp, the parameter based on the received periodic registration update timer value,

wherein the determining the RNA update timer value based on the parameter and the periodic registration update timer value comprises:

receiving, by a centralized unit of a RAN, the parameter from the near-real-time RIC over an E2 interface, and

determining, by the centralized unit, the RNA update timer based on the parameter and the periodic registration update timer value.

5 . The method as claimed in claim 4 , wherein the determining the parameter comprises:

determining whether the received periodic registration update timer value is greater than the predetermined maximum value for the RNA update timer;

based on the received periodic registration update timer value being greater than the predetermined maximum value for the RNA update timer, determining the parameter to be equal to (the predetermined maximum value for the RNA update timer/the received periodic registration update timer value); and

based on the received periodic registration update timer value being less than or equal to the predetermined maximum value for the RNA update timer, determining the parameter to be equal to ((the predetermined maximum value for the RNA update timer−the received periodic registration update timer value)/the predetermined maximum value for the RNA update timer).

6 . The method as claimed in claim 4 , wherein the determining, by the centralized unit, the RNA update timer value based on the parameter and the periodic registration update timer value comprises determining the RNA update timer value to be equal to (the parameter*the periodic registration update timer value) and rounding it off to a nearest RNA update timer value enumeration as specified in 3GPP specification.

7 . The method as claimed in claim 1 , wherein the RNA update timer value is determined by an xApp of a near-real-time RAN Intelligent Controller (RIC) using the periodic registration update timer value, and is provided to a centralized unit of a RAN over an E2 interface.

8 . The method as claimed in claim 7 , wherein the determining the RNA update timer value comprises:

determining whether the periodic registration update timer value is greater than the predetermined maximum value for the RNA update timer;

based on the periodic registration update timer value being greater than the predetermined maximum value for the RNA update timer, determining the RNA update timer value to be equal to the predetermined maximum value for the RNA update timer; and

based on the periodic registration update timer value being less than or equal to the predetermined maximum value for the RNA update timer, determining the RNA update timer value to be equal to (the periodic registration update timer value−(the periodic registration update timer value squared/the predetermined maximum value for the RNA update timer)).

9 . The method as claimed in claim 7 , wherein the determining the RNA update timer value comprises determining, by the xApp, the RNA update timer value based on an average user equipment (UE) residence time in the RAN.

10 . The method as claimed in claim 9 , wherein an average UE residence time in RAN is calculated in the xApp based on a UE admit time and a UE release time, averaged across a plurality of UEs.

11 . The method as claimed in claim 10 , wherein the xApp determines the UE admit time and the UE release time based on the UE admit and release events notified by the centralized unit (over E2).

12 . The method as claimed in claim 7 , wherein the determining the RNA update timer value comprises determining, by the xApp, the RNA update timer value based on an average downlink inter packet arrival gap in RRC-Inactive state.

13 . The method as claimed in claim 12 wherein the xApp determines the average downlink inter packet arrival gap based on an average time difference between two downlink data indications received for the UE.

14 . The method as claimed in claim 13 wherein an arrival of downlink data indication at the centralized unit (CU) is indicated to the xApp through the E2 interface.

15 . An apparatus for configuring a periodic radio access network (RAN) notification area (RNA) update timer based on a periodic registration update timer, the apparatus comprising:

a memory storing instructions; and

at least one processor configured to execute the instructions to:

obtain a periodic registration update timer value provided by a core network; and

determine a RNA update timer value based on the obtained periodic registration update timer value such that the RNA update timer value is less than the obtained periodic registration update timer value and less than a predetermined maximum value for the RNA update timer.

16 . The apparatus as claimed in claim 15 , wherein the at least one processor is further configured to:

determine a parameter based on the periodic registration update timer; and

determine the RNA update timer value based on the parameter and the periodic registration update timer value.

17 . The apparatus as claimed in claim 16 , wherein the at least one processor is further configured to determine the RNA update timer value further by configuring and/or updating the parameter via an O1 interface between a Service Management and Orchestration (SMO) framework and a centralized unit of a radio access network (RAN).

18 . The apparatus as claimed in claim 16 , wherein the at least one processor is further configured to determine the parameter by:

receiving, by an xApp of a near-real-time RAN Intelligent Controller (RIC), the periodic registration update timer value, and

determining, by the xApp, the parameter based on the received periodic registration update timer value; and

the determining the RNA update timer value based on the parameter and the periodic registration update timer value comprises:

receiving, by a centralized unit of a RAN, the parameter from the near-real-time RIC over an E2 interface, and

determining, by the centralized unit, the RNA update timer based on the parameter and the periodic registration update timer value.

19 . The apparatus as claimed in claim 18 , wherein the at least one processor is further configured to determine the parameter by:

determining whether the received periodic registration update timer value is greater than the predetermined maximum value for the RNA update timer;

based on the received periodic registration update timer value being greater than the predetermined maximum value for the RNA update timer, determining the parameter to be equal to (the predetermined maximum value for the RNA update timer/the received periodic registration update timer value); and

based on the received periodic registration update timer value being less than or equal to the predetermined maximum value for the RNA update timer, determining the parameter to be equal to ((the predetermined maximum value for the RNA update timer−the received periodic registration update timer value)/the predetermined maximum value for the RNA update timer).

20 . A non-transitory computer-readable recording medium having recorded thereon instructions executable by at least one processor, for performing a method of configuring a periodic radio access network (RAN) notification area (RNA) update timer based on a periodic registration update timer, the method comprising:

obtaining a periodic registration update timer value provided by a core network; and

determining a RNA update timer value based on the obtained periodic registration update timer value such that the RNA update timer value is less than the obtained periodic registration update timer value and less than a predetermined maximum value for the RNA update timer.