WO2025026565A1

WO2025026565A1 - Determining paging early indication for a subgroup of client devices

Info

Publication number: WO2025026565A1
Application number: PCT/EP2023/071570
Authority: WO
Inventors: Rama Kumar Mopidevi; Vishnu PREMAN; Jagdeep Singh Ahluwalia
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2023-08-03
Filing date: 2023-08-03
Publication date: 2025-02-06
Anticipated expiration: 2026-02-03

Abstract

Embodiments of the invention relate to a network node and a network access node for determining paging early indication for a subgroup of client devices in a communication system. The network node (100) transmits a first control message (510) to the network access node (300). The first control message (510) indicates to use a first paging subgrouping identity (ID1) and a second paging subgrouping identity (ID2) when determining a paging early indication for at least one client device (600). The network access node (300) upon receiving the first control message (510) determines the paging early indication for the at least one client device (600) using both the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2). Thereby, missing paging may be avoided. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

DETERMINING PAGING EARLY INDICATION FOR A SUBGROUP OF CLIENT DEVICES

TECHNICAL FIELD

Embodiments of the invention relate to a network node and a network access node for determining a paging early indication for a subgroup of client devices in a communication system. Furthermore, embodiments of the invention also relate to corresponding methods and a computer program.

BACKGROUND

In a conventional way of paging mechanism in 3GPP, a user equipment (UE) calculates paging occasion (PO) in a paging frame (PF). The PO calculation is based on the identity of the UE. The details of such PO calculations are specified in 3GPP TS 38.304.

As the paging channel has limited capacity, several UEs may be assigned to the same paging channel. UE receives paging downlink control information (DCI) and the paging message is scrambled by paging radio network temporary identifier (P-RNTI). The paging DCI and the paging message are always sent in the same time slot. There is only one P-RNTI defined and is shared by all UEs.

SUMMARY

An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

Another objective of embodiments of the invention is to provide a solution which reduces the probability that a client device misses paging massages in a communication system.

The above and further objectives are solved by the subject matter of the independent claims. Further embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objectives are achieved with a network node for a communication system, the network node being configured to: transmit a first control message to a network access node, the first control message indicating to use a first paging subgrouping identity and a second paging subgrouping identity when determining a paging early indication for at least one client device. An advantage of the network node according to the first aspect is that the probability of missed paging is reduced in the communication system as the network access node will calculate the paging early indication using the first and second paging subgrouping identities.

In an implementation form of a network node according to the first aspect, the first paging subgrouping identity and the second paging subgrouping identity are core network paging subgrouping identities.

An advantage with this implementation form is that missing paging can be reduced when both the first paging subgrouping identity and the second paging subgrouping identity have been generated by the core network.

In an implementation form of a network node according to the first aspect, the first control message further indicates the first paging subgrouping identity and the second paging subgrouping identity.

An advantage with this implementation form is that both paging subgrouping identities can be indicated in the same control message.

In an implementation form of a network node according to the first aspect, the first paging subgrouping identity is a radio access network paging subgrouping identity and the second paging subgrouping identity is a core network paging subgrouping identity.

An advantage with this implementation form is that the network node can provide the second paging subgrouping identity in subsequent registration procedures of the client device even though it does not provide the first paging subgrouping identity in the previous registration procedures of the client device.

In an implementation form of a network node according to the first aspect, the first control message further indicates the second paging subgrouping identity.

An advantage with this implementation form is that the second paging subgrouping identity can be indicated by the first control message itself without requiring any further control messages from the network node.

In an implementation form of a network node according to the first aspect, the first paging subgrouping identity has been determined at a first-time instance and the second paging subgrouping identity has been determined at a second time instance following the first-time instance.

An advantage with this implementation form is that the network node and the network access node can determine the paging subgrouping identities to use after the client device’s registration requests, i.e., the initial as well as subsequent registrations.

In an implementation form of a network node according to the first aspect, the first control message further indicates a first parameter defining a time period when both the first paging subgrouping identity and the second paging subgrouping identity are valid for determining the paging early indication for the client device.

An advantage with this implementation form is that the overhead of maintaining two paging subgrouping identities is limited to the time period defined by the first parameter.

In an implementation form of a network node according to the first aspect, the network node being configured to: transmit a second control message to the network access node, the second control message indicating a second parameter defining a time instance after which only the second paging subgrouping identity is valid for determining the paging early indication for the client device.

An advantage with this implementation form is that the network node and the network access node do not need to maintain both the subgrouping identities after the time instance defined by the second parameter and thus minimizing the overhead.

In an implementation form of a network node according to the first aspect, the second parameter is indicated by a flag.

An advantage with this implementation form is that the flag or a bit field is the simplest form of implementation and offers less overhead to the signaling message.

In an implementation form of a network node according to the first aspect, the first control message and/or the second control message is any of: an initial context setup request, a user equipment context modification request, a handover request, a path switching request acknowledgement, and a paging message. An advantage with this implementation form is that the existing message types with modifications can be used to carry the information related to the paging subgrouping identities according to the present solution.

In an implementation form of a network node according to the first aspect, the network node is part of a core network.

An advantage with this implementation form is that the client device’s idle mode paging handling is done by the network node.

According to a second aspect of the invention, the above mentioned and other objectives are achieved with a network access node for a communication system, the network access node being configured to: receive a first control message from a network node, the first control message indicating to use a first paging subgrouping identity and a second paging subgrouping identity when determining a paging early indication for at least one client device; and determine the paging early indication for the client device based on the first paging subgrouping identity and the second paging subgrouping identity.

An advantage of the network access node according to the second aspect is that the probability of missed paging is reduced in the communication system as the network access node will calculate the paging early indication using the first and second paging subgrouping identities.

In an implementation form of a network access node according to the second aspect, the first paging subgrouping identity and the second paging subgrouping identity are core network paging subgrouping identities.

In an implementation form of a network access node according to the second aspect, the first control message further indicates the first paging subgrouping identity and the second paging subgrouping identity.

An advantage with this implementation form is that both paging subgrouping identities can be indicated in the same control message. In an implementation form of a network access node according to the second aspect, the first paging subgrouping identity is a radio access network paging subgrouping identity and the second paging subgrouping identity is a core network paging subgrouping identity.

In an implementation form of a network access node according to the second aspect, the first control message further indicates the second paging subgrouping identity.

In an implementation form of a network access node according to the second aspect, the first paging subgrouping identity has been determined at a first-time instance and the second paging subgrouping identity has been determined at a second time instance following the firsttime instance.

An advantage with this implementation form is that the network node and the network access node can determine the paging subgrouping identities to use after the client device’s registration requests, i.e. , the initial as well as subsequent registrations.

In an implementation form of a network access node according to the second aspect, the first control message further indicates a first parameter defining a time period when both the first paging subgrouping identity and the second paging subgrouping identity are valid for determining the paging early indication for the client device, and wherein the network access node is configured to: determine the paging early indication for the client device based on the first paging subgrouping identity, the second paging subgrouping identity and the first parameter.

An advantage with this implementation form is that the overhead of maintaining two paging subgrouping identities is limited to the time period defined by the first parameter. In an implementation form of a network access node according to the second aspect, the network access node being configured to: receive a second control message from the network node, the second control message indicating a second parameter defining a time instance after which only the second paging subgrouping identity is valid for determining the paging early indication for the client device; and determine a paging early indication for the client device based on the second paging subgrouping identity and the second parameter.

In an implementation form of a network access node according to the second aspect, the second parameter is indicated by a flag.

In an implementation form of a network access node according to the second aspect, the first control message and/or the second control message is any of: an initial context setup request, a user equipment context modification request, a handover request, a path switching request acknowledgement, and a paging message.

An advantage with this implementation form is that the existing message types with modifications can be used to carry the information related to the paging subgrouping identities according to the present solution.

In an implementation form of a network access node according to the second aspect, the network access node configured to: transmit a third control message to the client device, the third control message indicating the paging early indication.

In an implementation form of a network access node according to the second aspect, the third control message is a downlink control information or a reference signal. In an implementation form of a network access node according to the second aspect, the network access node is part of a radio access network.

According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a network node, the method comprises: transmit a first control message to a network access node, the first control message indicating to use a first paging subgrouping identity and a second paging subgrouping identity when determining a paging early indication for at least one client device.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the network node according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network node.

The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the network node according to the first aspect.

According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a network access node, the method comprises: receiving a first control message from a network node, the first control message indicating to use a first paging subgrouping identity and a second paging subgrouping identity when determining a paging early indication for at least one client device; and determining the paging early indication for the client device based on the first paging subgrouping identity and the second paging subgrouping identity.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network access node.

The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the network access node according to the second aspect.

Embodiments of the invention also relate to a computer program, characterized in program code, which when run by at least one processor causes the at least one processor to execute any method according to embodiments of the invention. Further, embodiments of the invention also relate to a computer program product comprising a computer readable medium and the mentioned computer program, wherein the computer program is included in the computer readable medium, and may comprises one or more from the group of: read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), flash memory, electrically erasable PROM (EEPROM), hard disk drive, etc.

Further applications and advantages of embodiments of the invention will be apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

- Fig. 1 shows a network node according to an embodiment of the invention;

- Fig. 2 shows a flow chart of a method for a network node according to an embodiment of the invention;

- Fig. 3 shows a network access node according to an embodiment of the invention;

- Fig. 4 shows a flow chart of a method for a network access node according to an embodiment of the invention;

- Fig. 5 shows a communication system according to an embodiment of the invention; and

- Fig. 6 shows a signaling diagram illustrating further embodiments of the invention.

DETAILED DESCRIPTION

The UE wakes up and decodes the paging DCI and the paging message to check if the UE is paged. If multiple UEs share the same PO and only a few of them are paged, it’s a waste of power for UEs that are not paged. Therefore, paging early indication (PEI) was introduced as part of the 3GPP Rel-17 UE power saving work item. PEI notifies UEs of potentially relevant incoming paging such that these UEs are then able to skip PO in which they are not being paged, thus saving power. Subgrouping of UEs was introduced that allows waking up subgroups of UEs for potentially relevant paging.

It has been observed that a UE sometimes misses paging occasionally in the 5G network. Initially it was considered as an issue in the discontinuous reception (DRX) cycle mismatch between the UE and the network, but later detailed analysis showed that it’s the mismatch in the PEI with paging subgrouping (PEIPS) information stored in the UE and used by the network. There are two ways of subgrouping UEs:

• The core network (CN) performs subgrouping: paging subgrouping is allocated by an access and mobility management function (AMF) and the AMF informs the NG-RAN and NG-RAN will use the information to calculate PEIs. This is called PEI PS as previously mentioned. As per 3GPP TS 23.501 , the NG-RAN and the UE may use PEIPS to reduce UE’s power consumption. The information shared by CN to NG-RAN is denoted PEIPS assistance information.

• The radio access network (RAN) performs subgrouping: the subgrouping is based on UE’s temporary identity (ID) and is implemented within the NG-RAN. For paging subgrouping based on UE’s temporary ID, the UE’s support is included in the UE radio capability for paging which is specified in the RAN specifications.

In the Registration Request message, the Paging Subgrouping Support Indication indicates whether the UE supports PEIPS with AMF PEIPS assistance information or not. If the UE includes Paging Subgrouping Support Indication, the UE may also include the paging probability information to assist the AMF. If the AMF supports PEIPS assistance information and if the UE provides Paging Subgrouping Support Indication, the AMF stores the indication in the UE context in the AMF.

Thus, if the UE is initially registered with the network and the network did not send PEIPS assistance information to enable PEIPS in the UE, and if the UE and the RAN has a UE RAN Subgrouping UE_ID to page the UE, the RAN will use the RAN subgrouping to page the UE. Then later, in a registration procedure, if the UE and the network negotiate the PEIPS assistance information, the AMF will send the new PEIPS assistance information in the REGISTRATION ACCEPT message to the UE. The AMF will also send the PEIPS assistance information to the RAN as sending of the REGISTRATION ACCEPT message is considered as the completion of the procedure by the AMF. If the UE did not successfully receive the REGISTRATION ACCEPT message, the UE will still keep using the RAN subgrouping and the network will use the AMF subgrouping (i.e., PEIPS). This will result in the UE missing the paging. Thus, there is an issue with the existing signaling related to PEIPS that results in the UE missing paging.

For the above reasons it is herein disclosed a solution including a network node and a network access node for determining a PEI for a subgroup of client devices in a communication system. Fig. 1 shows a network node 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the network node 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The network node 100 may be configured for wired communications in a communication system. The wired communication capability may be provided with a wired communication interface 110 e.g., coupled to the transceiver 104.

The processor 102 may be referred to as one or more general-purpose central processing units (CPUs), one or more digital signal processors (DSPs), one or more application-specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, or one or more chipsets. The memory 106 may be a read-only memory, a random access memory (RAM), or a non-volatile RAM (NVRAM). The transceiver 104 may be a transceiver circuit, a power controller, or an interface providing capability to communicate with other communication modules or communication devices, such as network nodes and network servers. The transceiver 104, memory 106 and/or processor 102 may be implemented in separate chipsets or may be implemented in a common chipset.

That the network node 100 is configured to perform certain actions can in this disclosure be understood to mean that the network node100 comprises suitable means, such as e.g., the processor 102 and the transceiver 104, configured to perform the actions.

According to embodiments of the invention the network node 100 is configured to transmit a first control message 510 to a network access node 300, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600.

Furthermore, in an embodiment of the invention, the network node 100 for a communication system 500 comprises a transceiver configured to transmit a first control message 510 to a network access node 300, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600.

Moreover, in yet another embodiment of the invention, the network node 100 for a communication system 500 comprises a processor and a memory having computer readable instructions stored thereon which, when executed by the processor, cause the processor to: transmit a first control message 510 to a network access node 300, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600.

Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a network node 100, such as the one shown in Fig. 1. The method 200 comprises transmit 202 a first control message 510 to a network access node 300, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600.

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the network access node 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The network access node 300 further comprises a communication interface 310 coupled to the transceiver 304, which means that the network access node 300 is configured for communications in a communication system.

The processor 302 may be referred to as one or more general-purpose CPUs, one or more DSPs, one or more ASICs, one or more FPGAs, one or more programmable logic devices, one or more discrete gates, one or more transistor logic devices, one or more discrete hardware components, one or more chipsets. The memory 306 may be a read-only memory, a RAM, or a NVRAM. The transceiver 304 may be a transceiver circuit, a power controller, or an interface providing capability to communicate with other communication modules or communication devices. The transceiver 304, the memory 306 and/or the processor 302 may be implemented in separate chipsets or may be implemented in a common chipset.

That the network access node 300 is configured to perform certain actions can in this disclosure be understood to mean that the network access node 300 comprises suitable means, such as e.g., the processor 302 and the transceiver 304, configured to perform the actions.

According to embodiments of the invention the network access node 300 is configured to receive a first control message 510 from a network node 100, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600; and determine the PEI for the client device 600 based on the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2.

Furthermore, in an embodiment of the invention, the network access node 300 for a communication system 500 comprises a transceiver configured to receive a first control message 510 from a network node 100, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a paging early indication for at least one client device 600. The network access node 300 comprises a processor configured to determine the paging early indication for the client device 600 based on the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2.

Moreover, in yet another embodiment of the invention, the network access node 300 for a communication system 500 comprises a processor and a memory having computer readable instructions stored thereon which, when executed by the processor, cause the processor to: receive a first control message 510 from a network node 100, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a paging early indication for at least one client device 600; and determine the paging early indication for the client device 600 based on the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a network access node 300, such as the one shown in Fig. 3. The method 400 comprises receiving 402 a first control message 510 from a network node 100, the first control message 510 indicating to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a paging early indication for at least one client device 600; and determining 404 the paging early indication for the client device 600 based on the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2.

That is, the network access node 300 computes or calculates the PEI using both the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 as indicated in the first control message 510.

A least one client device may mean one or more client devices and may thus also be denoted a subgroup of client devices. A client device 600 herein may be denoted as a user device, a user equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and/or a mobile terminal, and is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket- storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via a radio access network (RAN), with another communication entity, such as another receiver or a server. The UE may further be a station, which is any device that contains an IEEE 802.11 -conformant MAC and PHY interface to the WM. The UE may be configured for communication in 3GPP related LTE, LTE-advanced, 5G wireless systems, such as NR, and their evolutions, as well as in IEEE related Wi-Fi, WiMAX and their evolutions.

Fig. 5 shows a communication system 500 according to embodiments of the invention. The communication system 500 in the disclosed embodiment comprises a network node 100 and a network access node 300 configured to communicate and operate in the communication system 500. The network node 100 may be an AMF while the network access node 300 may be a base station of a RAN. The network node 100 and the network access node 300 may communicate with each other using suitable communication interfaces. The network access node 300 may also be configured to communicate with client devices 600 by e.g., using standardized air interfaces which may be denoted downlink (DL) and uplink (UL) communications.

Further details related to embodiments of the invention will now be described in a 3GPP 5G context with reference to the signaling diagram of Fig. 6. Thus, 3GPP 5G terminology, definitions, expressions and system architecture may be used. Therefore, Fig. 6 shows a signaling diagram involving a network node 100 acting as an AMF of a CN, a network access node 300 acting as a gNB of a RAN, and a client device 600 acting as a UE. It may however be noted that embodiments of the invention are not limited thereto.

In step I in Fig. 6, the AMF 100 transmits a first control message 510 to a gNB 300. As aforementioned, the first control message 510 indicates to the gNB 300 to use a first paging subgrouping identity ID1 and a second paging subgrouping identity ID2 when determining a PEI for at least one client device 600. This indication may be performed with any suitable signaling such as using a new message type which is not yet defined in the specifications. It could e.g., be a new paging message type.

Thus, by receiving the first control message 510 the gNB 300 is instructed to use both the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 for computing the PEI for a subgroup of UEs. There are in this respect two main case depending on where and how the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 have been generated.

In a first case, the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 are CN paging subgrouping identities and thus both generated by the CN. In such cases the first control message 510 may further indicate the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 in addition to indicate the use of both ID1 and ID2 for computing the PEI.

In a second case, the first paging subgrouping identity ID1 is a RAN paging subgrouping identity while the second paging subgrouping identity ID2 is a CN paging subgrouping identity. In such cases the first control message 510 may further indicate the second paging subgrouping identity ID2 but not the first paging subgrouping identity ID1 which is not generated by the CN and thus not transmitted by the AMF 100 to the gNB 300. Instead, the gNB 300 determines that it has to use a RAN paging subgrouping identity when it does not receive paging subgrouping identity from the AMF 100 and the UE capabilities. For example, in the initial registration request, if the AMF 100 does not want to use a core network paging subgrouping identity, the RAN will use a RAN paging subgrouping identity if the UE capabilities allow it. Hence, the first subgrouping identity ID1 can be determined at an initial registration request or a registration request that is performed periodically and the second paging subgrouping identity ID2 can be determined at any of the subsequent registration requests.

It may be observed that the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 generally have been determined at different time instances. Hence, in embodiments of the invention, the first paging subgrouping identity ID1 has been determined at a first-time instance T1 and the second paging subgrouping identity ID2 has been determined at a second time instance T2 following the first-time instance T1.

In step II in Fig. 6, the gNB 300 receives the first control message 510 and determines the PEI for a subgroup of UEs 600 by using both the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 as e.g., specified in 3GPP TS 38.304 for each subgrouping identity.

Moreover, the first control message 510 may in embodiments of the invention further indicate a first parameter P1 defining a time period when both the first paging subgrouping identity ID1 and the second paging subgrouping identity ID2 are valid for determining the PEI for the subgroup of UEs 600. If this is the case the gNB 300 determines the PEI for the subgroup of UEs 600 based on the first paging subgrouping identity ID1 , the second paging subgrouping identity ID2 and the first parameter P1. That is, during the period when both ID1 and ID2 are valid as indicated by the first parameter P1. Thus, by defining the time period as indicated by the first parameter P1 , the gNB 300 uses both the first and second subgroup IDs only for the time period and the overhead introduced is only for the duration defined by the first parameter P1.

In step III in Fig. 6, the gNB 300 prepares and transmits a third control message 530 to the subgroup of UEs. The third control message 530 indicates the computed PEI for the subgroup of UEs 600.

In step IV in Fig. 6, the subgroup of UEs 600 receives the third control message 530 in a downlink control information (DCI) or in a reference signal. The latter may e.g., be in the secondary synchronization signal. Upon reception of the PEI the subgroup of UEs will decode the PEI and depending on the PEI, the UEs that are notified about paging will further monitor the PO.

In step V in Fig. 6, the AMF 100 may in embodiments of the invention transmit a second control message 520 to the gNB 300. The second control message 520 indicates a second parameter P2 which defines a time instance after which only the second paging subgrouping identity ID2 is valid for determining the PEI for the subgroup of UEs. The indication of the second parameter P2 may be performed by a flag such as a bit flag.

In step VI in Fig. 6, the gNB 300 upon reception of the second control message 520 determines a new PEI for the subgroup of UEs 600 by only using the second paging subgrouping identity ID2 from time instance defined by the second parameter P2. The new PEI is transmitted to the subgroup of UEs 600 in a new third control message 530'.

In step VII in Fig. 6, the subgroup of UEs 600 uses the new PEI as previously mentioned with reference to step III.

The first 510 and second 520 control messages may be signaled in a number of different ways and in different message types. For example, the first control message 510 and/or the second control message 520 may be any of the existing signaling protocols:

• an initial context setup request,

• a user equipment context modification request, • a handover request,

• a path switching request acknowledgement, and

• a paging message.

The existing signaling messages can be modified/extended to carry the information content in the first 510 and second 520 control messages as the existing messages already carry the paging subgrouping identity.

However, the information content in the first 510 and second 520 control messages may also be signaled through new message type yet not standardized. For example, the new message can be a dedicated signaling message indicating the second paging subgrouping identity, the time period parameter P1 and the bit flag indicating the validity of the second paging subgrouping identity.

A network node 100 herein may also be denoted as an AMF or any corresponding network function in a communication system.

A network access node 300 herein may also be denoted as a radio network access node, an access network access node, an access point (AP), or a base station (BS), e.g., a radio base station (RBS), which in some networks may be referred to as transmitter, “gNB”, “gNodeB”, “eNB”, “eNodeB”, “NodeB” or “B node”, depending on the standard, technology and terminology used. The radio network access node may be of different classes or types such as e.g., macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby the cell size. The radio network access node may further be a station, which is any device that contains an IEEE 802.11 -conformant media access control (MAC) and physical layer (PHY) interface to the wireless medium (WM). The radio network access node may be configured for communication in 3GPP related long term evolution (LTE), LTE-advanced, fifth generation (5G) wireless systems, such as new radio (NR) and their evolutions, as well as in IEEE related Wi-Fi, worldwide interoperability for microwave access (WiMAX) and their evolutions.

Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as previously mentioned a ROM, a PROM, an EPROM, a flash memory, an EEPROM, or a hard disk drive. Moreover, it should be realized that the network node 100 and the network access node 300 comprise the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing or implementing embodiments of the invention. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged together for performing the solution.

Therefore, the processor(s) of the network node 100 and the network access node 300 may comprise, e.g., one or more instances of a CPU, a processing unit, a processing circuit, a processor, an ASIC, a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like.

Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A network node (100) for a communication system (500), the network node (100) being configured to: transmit a first control message (510) to a network access node (300), the first control message (510) indicating to use a first paging subgrouping identity (ID1) and a second paging subgrouping identity (ID2) when determining a paging early indication for at least one client device (600).

2. The network node (100) according to claim 1 , wherein the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2) are core network paging subgrouping identities.

3. The network node (100) according to claim 2, wherein the first control message (510) further indicates the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2).

4. The network node (100) according to claim 1 , wherein the first paging subgrouping identity (ID1) is a radio access network paging subgrouping identity and the second paging subgrouping identity (ID2) is a core network paging subgrouping identity.

5. The network node (100) according to claim 4, wherein the first control message (510) further indicates the second paging subgrouping identity (ID2).

6. The network node (100) according to any one of the preceding claims, wherein the first paging subgrouping identity (ID1) has been determined at a first-time instance (T1) and the second paging subgrouping identity (ID2) has been determined at a second time instance (T2) following the first-time instance (T1).

7. The network node (100) according to any one of the preceding claims, wherein the first control message (510) further indicates a first parameter (P1) defining a time period when both the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2) are valid for determining the paging early indication for the client device (600).

8. The network node (100) according to any one of the preceding claims, configured to: transmit a second control message (520) to the network access node (300), the second control message (520) indicating a second parameter (P2) defining a time instance after which only the second paging subgrouping identity (ID2) is valid for determining the paging early indication for the client device (600).

9. The network node (100) according to claim 8, wherein the second parameter (P2) is indicated by a flag.

10. The network node (100) according to any one of the preceding claims, wherein the first control message (510) and/or the second control message (520) is any of: an initial context setup request, a user equipment context modification request, a handover request, a path switching request acknowledgement, and a paging message.

11 . The network node (100) according to any one of the preceding claims, wherein the network node (100) is part of a core network.

12. A network access node (300) for a communication system (500), the network access node (300) being configured to: receive a first control message (510) from a network node (100), the first control message (510) indicating to use a first paging subgrouping identity (ID1) and a second paging subgrouping identity (ID2) when determining a paging early indication for at least one client device (600); and determine the paging early indication for the client device (600) based on the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2).

13. The network access node (300) according to claim 12, wherein the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2) are core network paging subgrouping identities.

14. The network access node (300) according to claim 13, wherein the first control message (510) further indicates the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2).

15. The network access node (300) according to claim 12, wherein the first paging subgrouping identity (ID1) is a radio access network paging subgrouping identity and the second paging subgrouping identity (ID2) is a core network paging subgrouping identity.

16. The network access node (300) according to claim 15, wherein the first control message (510) further indicates the second paging subgrouping identity (ID2).

17. The network access node (300) according to any one of claims 12 to 16, wherein the first paging subgrouping identity (ID1) has been determined at a first-time instance (T1) and the second paging subgrouping identity (ID2) has been determined at a second time instance (T2) following the first-time instance (T1).

18. The network access node (300) according to any one of claims 12 to 17, wherein the first control message (510) further indicates a first parameter (P1) defining a time period when both the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2) are valid for determining the paging early indication for the client device (600), and wherein the network access node (300) is configured to: determine the paging early indication for the client device (600) based on the first paging subgrouping identity (ID1), the second paging subgrouping identity (ID2) and the first parameter (P1).

19. The network access node (300) according to any one of claims 12 to 18, configured to: receive a second control message (520) from the network node (100), the second control message (520) indicating a second parameter (P2) defining a time instance after which only the second paging subgrouping identity (ID2) is valid for determining the paging early indication for the client device (600); and determine a paging early indication for the client device (600) based on the second paging subgrouping identity (ID2) and the second parameter (P2).

20. The network access node (300) according to claim 19, wherein the second parameter (P2) is indicated by a flag.

21. The network access node (300) according to any one of claims 12 to 20, wherein the first control message (510) and/or the second control message (520) is any of: an initial context setup request, a user equipment context modification request, a handover request, a path switching request acknowledgement, and a paging message.

22. The network access node (300) according to any one of claims 12 to 21 , configured to: transmit a third control message (530) to the client device (600), the third control message (530) indicating the paging early indication.

23. The network access node (300) according to claim 22, wherein the third control message (530) is a downlink control information or a reference signal.

24. The network access node (300) according to any one of claims 12 to 23, wherein the network access node (300) is part of a radio access network.

25. A method (200) for a network node (100), the method (200) comprising: transmit (202) a first control message (510) to a network access node (300), the first control message (510) indicating to use a first paging subgrouping identity (ID1) and a second paging subgrouping identity (ID2) when determining a paging early indication for at least one client device (600).

26. A method (400) for a network access node (300), the method (400) comprising: receiving (402) a first control message (510) from a network node (100), the first control message (510) indicating to use a first paging subgrouping identity (ID1) and a second paging subgrouping identity (ID2) when determining a paging early indication for at least one client device (600); and determining (404) the paging early indication for the client device (600) based on the first paging subgrouping identity (ID1) and the second paging subgrouping identity (ID2).

27. A computer program with a program code for performing a method according to claim 25 or 26 when the computer program runs on a computer.