WO2023187595A1

WO2023187595A1 - Apparatus, methods, and computer programs for multicast sessions in rrc inactive

Info

Publication number: WO2023187595A1
Application number: PCT/IB2023/052958
Authority: WO
Inventors: Horst Thomas BELLING; Philippe Godin
Original assignee: Nokia Technologies Oy
Priority date: 2022-03-29
Filing date: 2023-03-24
Publication date: 2023-10-05
Also published as: GB202204466D0

Abstract

There is provided an apparatus for an access node (802), that causes the access node to: receive (8001) a request for activation of a multicast session; determine (8003), for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signal (8004), for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmit data of the multicast session in the at least one cell using the determined transmission mode.

Description

APPARATUS, METHODS, AND COMPUTER PROGRAMS FOR MULTICAST SESSIONS IN RRC INACTIVE

Related Applications

[0001 ]This patent application claims the benefit of priority of United Kingdom Patent Application No. 2204466.3, filed March 29, 2022, which is hereby incorporated by reference in its entirety.

Field

[0002] Various examples described herein generally relate to apparatus, methods, and computer programs, and more particularly (but not exclusively) to apparatus, methods and computer programs for network apparatuses.

Background

[0003] In general, a communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, access nodes and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided, for example, by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on. Content may be multicast or uni-cast to communication devices.

[0004]A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user is often referred to as user equipment (UE) or user device. The communication device may access a carrier provided by an access node and transmit and/or receive communications on the carrier.

[0005]The communication system and associated devices typically operate in accordance with a required standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Another example of an architecture is the long-term evolution (LTE) or the Universal Mobile Telecommunications System (UMTS) radio-access technology. Another example communication system is so called 5G system that allows user equipment (UE) or user device to contact a 5G core via e.g., new radio (NR) access technology or via other access technology such as Untrusted access to 5GC or wireline access technology.

[0006] In 5G, a UE Registration Area (RA) comprises a list of one or more Tracking Areas (TA). A Tracking Area is a logical concept of an area where a UE can move around without updating the network. The network can allocate a list with one or more TAs to the UE.

Summary

[0007] According to a first aspect, there is provided an apparatus for an access node, the apparatus comprising means for: receiving a request for activation of a multicast session; determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting data of the multicast session in the at least one cell using the determined transmission mode.

[0008]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0009]The request may be received from a core network function or a neighbouring radio access network node.

[0010]The apparatus may further comprise means for receiving an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node.

[0011]The means for determining may comprise means for determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration. [0012]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0013]The apparatus may comprise means for transmitting the signalled indication only when the multicast session is active.

[0014]The signalled indication may comprise an identifier of the multicast session.

[0015]The means for signalling the indication may comprise means for signalling the indication using a broadcast channel.

[0016]The means for signalling may comprise means for signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

[0017]The apparatus may further comprise means for repeatedly signalling said indication that the multicast session is activated while the multicast session is active. [0018]The apparatus may further comprise means for: determining area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signalling a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node

[0019] The request for the activation for the multicast service to the at least neighbouring RAN node may comprises an XnAP RAN Multicast Group paging request.

[0020] According to a second aspect, there is provided an apparatus for a user equipment, the apparatus comprising means for: receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0021] Said indication may be an explicit indication that indicates whether the multicast session is active or inactive.

[0022] Said indication may be only received when the multicast session is active. [0023]Said indication may comprise an identifier of the multicast session. [0024] The apparatus may further comprise means for receiving said indication via a broadcast channel.

[0025] The apparatus may further comprise means for receiving said indication via a Radio Access Network paging request for the multicast session.

[0026]The apparatus may further comprise means for repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

[0027] According to a third aspect, there is provided an apparatus for an access node, the apparatus comprising: at least one processor; and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to: receive a request for activation of a multicast session; determine, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signal, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmit data of the multicast session in the at least one cell using the determined transmission mode.

[0028]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0029]The request may be received from a core network function or a neighbouring radio access network node.

[0030]The apparatus may further be caused to receive an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node.

[0031 ]The determining may comprise determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration. [0032]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0033]The apparatus may be caused to transmit the signalled indication only when the multicast session is active.

[0034]The signalled indication may comprise an identifier of the multicast session. [0035]The signalling the indication may comprise signalling the indication using a broadcast channel.

[0036]The signalling may comprise signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

[0037]The apparatus may further be caused to repeatedly signal said indication that the multicast session is activated while the multicast session is active.

[0038]The apparatus may further be caused to: determine area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signal a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node

[0039] The request for the activation for the multicast service to the at least neighbouring RAN node may comprises an XnAP RAN Multicast Group paging request.

[0040] According to a fourth aspect, there is provided an apparatus for a user equipment, the apparatus comprising: at least one processor; and at least one memory comprising code that, when executed by the at least one processor, causes the apparatus to: receive, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receive data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0041] Said indication may be an explicit indication that indicates whether the multicast session is active or inactive.

[0042] Said indication may be only received when the multicast session is active. [0043]Said indication may comprise an identifier of the multicast session.

[0044]The apparatus may further be caused to receive said indication via a broadcast channel.

[0045] The apparatus may further be caused to receive said indication via a Radio Access Network paging request for the multicast session. [0046] The apparatus may further be caused to repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

[0047] According to a fifth aspect, there is provided a method for an apparatus for an access node, the method comprising: receiving a request for activation of a multicast session; determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting data of the multicast session in the at least one cell using the determined transmission mode.

[0048]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0049]The request may be received from a core network function or a neighbouring radio access network node.

[0050] The method may further comprising receiving an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node.

[0051 ]The determining may comprise determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration. [0052]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0053]The method may comprise transmitting the signalled indication only when the multicast session is active.

[0054]The signalled indication may comprise an identifier of the multicast session.

[0055]The signalling the indication may comprise signalling the indication using a broadcast channel.

[0056]The signalling may comprise signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session. [0057]The method may further comprise repeatedly signalling said indication that the multicast session is activated while the multicast session is active.

[0058]The method may further comprise: determining area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signalling a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node [0059] The request for the activation for the multicast service to the at least neighbouring RAN node may comprises an XnAP RAN Multicast Group paging request.

[0060] According to a sixth aspect, there is provided a method for an apparatus for a user equipment, the method comprising: receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0061] Said indication may be an explicit indication that indicates whether the multicast session is active or inactive.

[0062] Said indication may be only received when the multicast session is active. [0063]Said indication may comprise an identifier of the multicast session.

[0064]The method may further comprise receiving said indication via a broadcast channel.

[0065]The method may further comprise receiving said indication via a Radio Access Network paging request for the multicast session.

[0066]The method may further comprise repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

[0067] According to a seventh aspect, there is provided an apparatus for an access node, the apparatus comprising: receiving circuitry for receiving a request for activation of a multicast session; determining circuitry for determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; signalling circuitry for, when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting circuitry for transmitting data of the multicast session in the at least one cell using the determined transmission mode. [0068]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0069]The request may be received from a core network function or a neighbouring radio access network node.

[0070]The apparatus may further comprise receiving circuitry for receiving an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node.

[0071 ]The determining circuitry for determining may comprise determining circuitry for determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration.

[0072]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0073]The apparatus may comprise transmitting circuitry for transmitting the signalled indication only when the multicast session is active.

[0074]The signalled indication may comprise an identifier of the multicast session.

[0075]The signalling circuitry for signalling the indication may comprise signalling circuitry for signalling the indication using a broadcast channel.

[0076]The signalling circuitry for signalling may comprise signalling circuitry for signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

[0077] The apparatus may further comprise signalling circuitry for repeatedly signalling said indication that the multicast session is activated while the multicast session is active.

[0078]The apparatus may further comprise: determining circuitry for determining area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signalling circuitry for signalling a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node

[0079] The request for the activation for the multicast service to the at least neighbouring RAN node may comprises an XnAP RAN Multicast Group paging request.

[0080] According to an eighth aspect, there is provided an apparatus for a user equipment, the apparatus comprising: receiving circuitry for receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving circuitry for receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0081] Said indication may be an explicit indication that indicates whether the multicast session is active or inactive.

[0082] Said indication may be only received when the multicast session is active.

[0083]Said indication may comprise an identifier of the multicast session.

[0084]The apparatus may further comprise receiving circuitry for receiving said indication via a broadcast channel.

[0085]The apparatus may further comprise receiving circuitry for receiving said indication via a Radio Access Network paging request for the multicast session.

[0086]The apparatus may further comprise receiving circuitry for repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

[0087] According to a ninth aspect, there is provided non-transitory computer readable medium comprising program instructions for causing an apparatus for an access node to perform at least the following: receive a request for activation of a multicast session; determine, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signal, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmit data of the multicast session in the at least one cell using the determined transmission mode.

[0088]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0089]The request may be received from a core network function or a neighbouring radio access network node.

[0090]The apparatus may further be caused to receive an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node.

[0091 ]The determining may comprise determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration. [0092]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0093]The apparatus may be caused to transmit the signalled indication only when the multicast session is active.

[0094]The signalled indication may comprise an identifier of the multicast session.

[0095]The signalling the indication may comprise signalling the indication using a broadcast channel.

[0096]The signalling may comprise signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

[0097]The apparatus may further be caused to repeatedly signal said indication that the multicast session is activated while the multicast session is active.

[0098]The apparatus may further be caused to: determine area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signal a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node [0099] The request for the activation for the multicast service to the at least neighbouring RAN node may comprises an XnAP RAN Multicast Group paging request.

[0100] According to a tenth aspect, there is provided non-transitory computer readable medium comprising program instructions for causing an apparatus for a user equipment to perform at least the following: receive, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receive data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0101] Said indication may be an explicit indication that indicates whether the multicast session is active or inactive.

[0102] Said indication may be only received when the multicast session is active. [0103]Said indication may comprise an identifier of the multicast session.

[0104]The apparatus may further be caused to receive said indication via a broadcast channel.

[0105] The apparatus may further be caused to receive said indication via a Radio Access Network paging request for the multicast session.

[0106] The apparatus may further be caused to repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

[0107] According to an eleventh aspect, there is provided a computer program product stored on a medium that may cause an apparatus to perform any method as described herein.

[0108] According to a twelfth aspect, there is provided an electronic device that may comprise apparatus as described herein.

[0109] According to a thirteenth aspect, there is provided a chipset that may comprise an apparatus as described herein.

Brief description of Figures

[0110] Some examples, will now be described, merely by way of illustration only, with reference to the accompanying drawings in which:

[0111] Figures 1A and 1 B show a schematic representation of a 5G system;

[0112] Figure 2 shows a schematic representation of a network apparatus;

[0113] Figure 3 shows a schematic representation of a user equipment; [0114] Figure 4 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the methods of some examples;

[0115] Figure 5 shows a schematic representation of a network;

[0116] Figures 6 to 7 illustrate signalling operations;

[0117] Figure 8 illustrates example signalling between communication entities described herein; and

[0118] Figures 9 and 10 are flow charts illustrating example operations that may be performed by apparatus described herein.

Detailed description

[0119] In the following description of examples, certain aspects are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. For brevity and clarity, the following describes such aspects with reference to a 5G wireless communication system. However, it is understood that such aspects are not limited to 5G wireless communication systems, and may, for example, be applied to other wireless communication systems (for example, current 6G proposals).

[0120] Before describing in detail the examples, certain general principles of a 5G wireless communication system are briefly explained with reference to Figures 1 A and 1 B.

[0121] Figure 1A shows a schematic representation of a 5G system (5GS) 100. The 5GS may comprise a user equipment (UE) 102 (which may also be referred to as a communication device or a terminal), a 5G access network (AN) (which may be a 5G Radio Access Network (RAN) or any other type of 5G AN such as a Non-3GPP Interworking Function (N3IWF) /a Trusted Non3GPP Gateway Function (TNGF) for Untrusted / Trusted Non-3GPP access or Wireline Access Gateway Function (W-AGF) for Wireline access) 104, a 5G core (5GC) 106, one or more application functions (AF) 108 and one or more data networks (DN) 1 10.

[0122]The 5G RAN may comprise one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) unit functions. The RAN may comprise one or more access nodes. [0123]The 5GC 106 may comprise one or more Access and Mobility Management Functions (AMF) 1 12, one or more Session Management Functions (SMF) 114, one or more authentication server functions (AUSF) 1 16, one or more unified data management (UDM) functions 1 18, one or more user plane functions (UPF) 120, one or more unified data repository (UDR) functions 122, one or more network repository functions (NRF) 128, and/or one or more network exposure functions (NEF) 124. The role of an NEF is to provide secure exposure of network services (e.g. voice, data connectivity, charging, subscriber data, and so forth) towards a 3rd party. Although NRF 128 is not depicted with its interfaces, it is understood that this is for clarity reasons and that NRF 128 may have a plurality of interfaces with other network functions.

[0124]The 5GC 106 also comprises a network data analytics function (NWDAF) 126. The NWDAF is responsible for providing network analytics information upon request from one or more network functions or apparatus within the network. Network functions can also subscribe to the NWDAF 126 to receive information therefrom. Accordingly, the NWDAF 126 is also configured to receive and store network information from one or more network functions or apparatus within the network. The data collection by the NWDAF 126 may be performed based on at least one subscription to the events provided by the at least one network function.

[0125]The network may further comprise a management data analytics service (MDAS) producer or MDAS Management Service (MnS) producer. The MDAS MnS producer may provide data analytics in the management plane considering parameters including, for example, load level and/or resource utilization. For example, the MDAS MnS producer for a network function (NF) may collect the NF’s load-related performance data, e.g., resource usage status of the NF. The analysis of the collected data may provide forecast of resource usage information in a predefined future time window. This analysis may also recommend appropriate actions e.g., scaling of resources, admission control, load balancing of traffic, and so forth.

[0126] Figure 1 B shows a schematic representations of a 5GC represented in current 3GPP specifications. It is understood that this architecture is intended to illustrate potential components that may be comprised in a core network, and the presently described principles are not limited to core networks comprising only the described components. [0127] Figure 1 B shows a 5GC 106’ comprising a UPF 120’ connected to an SMF 114’ over an N4 interface. The SMF 114’ is connected to each of a UDM 122’, an NEF 124’, an NWDAF 126’, an AF 108’, a Policy Control Function (PCF) 130’, an AMF 1 12’, and a Charging function 132’ over an interconnect medium that also connects these network functions to each other. The 5G core 106’ further comprises a network repository function (NRF) 133’ and a network function 134’ that connect to the interconnect medium.

[0128]3GPP refers to a group of organizations that develop and release different standardized communication protocols. 3GPP develops and publishes documents pertaining to a system of “Releases” (e.g., Release 15, Release 16, and beyond).

[0129] In telecommunications, a registration area (RA) comprises a list of Tracking Areas (TAs) for a UE. A registration area contains one or more TAs in which the UE can be paged. Each TA may comprise one or more cells that are controlled by one or more respective base stations.

[0130] Paging allows the network to reach UEs in RRCJDLE and in RRCJNACTIVE state through Paging messages, and to notify UEs in RRCJDLE, RRCJNACTIVE and RRC_CONNECTED state of system information change and Earthquake and Tsunami Warning System (ETWS)/Commercial Mobile Alert System (CMAS) indications through Short Messages. Both Paging messages and Short Messages are addressed with a paging temporary identifier (e.g., a paging radio network temporary identifier (P-RNTI)) on the physical downlink control channel (PDCCH). However, while the former is sent on a Paging control channel, the latter is sent over PDCCH directly.

[0131]While in RRCJDLE the UE monitors the paging channels for Core network- initiated paging. In addition to this, in an RRCJNACTIVE the UE also monitors paging channels for Radio Access Network-initiated paging. A UE need not monitor paging channels continuously though.

[0132]SA2 has defined 5G multicast and broadcast procedures in TS 23.247. SA2 has agreed a Rel-18 study on enhancements for 5G multicast-broadcast services in TR 23.700-47.

[0133] In Rel-17, MBS (multicast and broadcast services) procedures distribution area of a multicast session is determined by the presence of UEs that joined the multicast session in cells. The distribution area may be further restricted by a service area defined for the multicast session: The data of the multicast session is only distributed in cells within that service area where UEs within the multicast session are present.

[0134] For inactive UEs the location is not known at cell level, only at RNA (RAN based Notification Area) level. UEs can move between cells within an area configured by NG- RAN (the RNA) without notifying NG-RAN (see TS 38.300). An RNA can be a tracking area or a part of a tracking area, or be denoted by cell IDs.

[0135]The Technical Specification Group Service and System Aspects (TSG-SA) comprises a collection of groups that is responsible for the overall architecture and service capabilities of systems based on 3GPP specifications

[0136] One of these groups, SA2, has defined 5G multicast and broadcast procedures in 3GPP TS 23.247.

[0137]SA2 has further agreed a Release-18 study on enhancements for 5G multicastbroadcast services in TR 23.700-47. At least one of the objectives of this study is to study possible further enhancement of Multicast and Broadcast services (MBS) for a large number of UEs, particularly by enabling UEs receiving Multicast MBS Session data in Radio Resource Control (RRC) states such as, for example, the RRC Inactive state. The RRC Inactive state support often requires collaboration with Radio Access Network (RAN) working groups in 3GPP in order to enable efficient operation.

[0138] Figure 6 illustrates example signaling that may be performed between various communication and/or network elements for activating an MBS session.

[0139] Figure 6 illustrates example signalling that may be performed between a user equipment (UE) 601 , a Next-Generation Radio Access Network (NG-RAN) 602, an Access and Mobility Function (AMF) 603, a Session Management Function (SMF) 604, a User Plane Function (UPF) 605, a Multicast-Broadcast UPF (MB-UPF) 606, and a MB-SMF 607.

[0140]At 6001 , the MB-UPF 606 and the MB-SMF 607 exchange signalling after an MBS session activation is triggered for an MBS service. This may be triggered in any of a plurality of cases. For example, this MBS service activation may be triggered when the MB-UPF 606 receives downlink data for a multicast MBS session. This MBS service activation may be triggered based on receipt, at the MB-UPF 606, of an instruction from the MB-SMF to activate an MBS service. The MB-UPF may send and “N4mb Notification” comprising a Session identifier to the MB-SMF for indicating the arrival of the downlink MBS data. As another example, the MBS service activation may be performed in response to an application function (not shown) sending an MBS Activation request comprising a multicast session identifier (e.g., a Temporary Mobile Group Identity (TMGI)) to the MB-SMF (either directly or through another network element, such as a network exposure function).

[0141 ] At 6002, the MB-SMF 607 signals the SMF 604. This signalling of 6002 may indicate that an MBS service is being activated. Using 3GPP terminology, this signalling of 6002 may comprise an Nmbsmf MBSSession ContextStatusNotify signal, and may comprise a session identifier for the MBS session being activated, in addition to an explicit indication that a multicast session is being activated. (MBS Session ID).

[0142] In response to the signalling of 6002, the SMF may sets a related multicast MBS session state as an "Active" state and determine a set of UEs that joined the multicast MBS session identified by the related MBS session identifier. When the SMF determines the user plane of the associated PDU session(s) of the UE(s) with respect to the MBS session identifier, are activated already, the signalling proceeds to 6012 and does not perform 6003 to 6011 . Otherwise, steps 6003 to 6011 may be performed. [0143] At 6003, the SMF 604 signals the AMF. This signalling may identify UE in the determined set of UE (which may comprise one or more than one UE), and request at least one address for notifying those UE in the determined set in relation to the MBS service. This signalling of 6003 may be labelled as a an Namf MT EnableGroupReachability Request. This signalling of 6003 may further comprise the MBS session identifier. This signaling of 6003 may identify those UEs in the determined sets using at least one session identifier (e.g., a packet data unit (PDU) session identifier) of sessions associated with at least one UE in the determined set. When later UE is reachable, the UE reachability Notification Address may be used by the AMF to identify and notify the related SMF.

[0144]After receiving the request at 6003, for each UE in the set the AMF determines the connection management state of the UE. This is illustrated with respect to 6004 to 6011.

[0145] For those UEs that are involved in the multicast MBS Session (i.e., comprised in the determined set) and in a CONNECTED state, the AMF 603 indicates those UEs to the SMF 605 at 6004. This may be performed using an Namf MT EnableGroupReachability Response that comprises a UE list. Otherwise, the response does not include UE list. [0146] At 6005, for each UE in the UE list included in 6004, when the Quality of Service (QoS) profile(s) for associated QoS flow(s) has not yet been provided for the PDU session(s) associated with those UE, the SMF provides QoS profile information for those UE to the AMF 603. This may be performed using an Namf_Communication_N1 N2MessageTransfer. This signalling may further provide mapping information between any unicast QoS flow and any multicast QoS flow for those UE. The associated QoS profiles as well as the mapping information between the unicast QoS flow and multicast QoS flow may be included to support the 5GC Individual MBS traffic delivery.

[0147] 6006 to 6011 are performed when the AMF 603 determines that there are UEs in IDLE state and involved in the multicast MBS Session (when there are no UEs in an IDLE state, the mechanism may skip to 6012).

[0148]At 6006, the AMF determines a Paging Area covering all the registration areas of those UE(s) in the IDLE state comprised in the set, and sends a paging request message to the NG-RAN node(s) belonging to this Paging Area using the MBS session identifier as the identifier to be paged if the related NG-RAN node(s) support MBS. When the NG-RAN node(s) for that paging area does not support MBS, the AMF603 sends a Paging message to the NG-RAN node(s) per UE without using the MBS Session identifier.

[0149]At 6007, a paged UE 601 signals the AMF 603. This signalling of 6007 may comprise a service request message.

[0150]At 6008, after receiving the service request message of 6007, the AMF 603 may signal the SMF 604 to update a context for the UE 601 at the SMF 604. This signalling may be performed using an Nsmf PDUSession UpdateSMContext request message.

[0151]At 6009, the SMF 604 may respond to the signalling of 6008. This response may comprise, for example, an Nsmf PDUSession UpdateSMContext response message. This response may indicate that the context has been updated. Subsequent to this, the mechanism may skip to 6012.

[0152] For those UE that do not respond o the paging request of 6006, 6010 and 601 1 are performed.

[0153] At 6010, the AMF 603 signals the SMF 604. This signaling of 6010 informs the SMF 6004 of the paging failure. This may be signaled using, for example, an Namf MT UEReachabilitylnfoNotify message. [0154]The SMF 604 may respond to the signalling of 6010 at 601 1. At 601 1 , for UE that are indicated as reachable 6010, or user plane of the associated PDU session is activated already but the QoS profile(s) for associated QoS flow(s) needs to be provided for the PDU session, the SMF may invokes Namf_Communication_N1 N2MessageTransfer (N2 SM information ()) to the AMF at 6011.

[0155] At 60012, the AMF 603 sends an N2 request message comprising N2 session management information to the RAN node 602. The N2 interface supports control plane signalling between RAN and 5G core covering scenarios related to UE context management, PDU session/resource management procedures.

[0156]6013 is performed when a shared tunnel has not been established before. During 6013, a shared tunnel is established.

[0157] During 6014, when 5G core Individual MBS traffic delivery is used, the SMF 604 configures the UPF 605 for individual delivery and requests the MB-SMF 607 to configure the MB-UPF 606 to send multicast data to the UPF 605.

[0158] During 6015, the MB-SMF 607 determines that there are shared tunnels established and, in response to this determination, signals the AMF 603. This signalling of 6015 may comprise the MBS session identifier. This signalling of 6015 may comprise Namf_MBSCommunication_N2MessageTransfer Request signalling.

[0159] At 6016, the AMF 603 signals an activation request to the NG-RAN node(s) 602 associated with the UE 601 comprised in the set that are in CONNECTED state. This signalling may comprise an NGAP activation request message. For those UEs in the set that have joined in the MBS Session and are in an RRC-INACTI VE state, the RAN nodes may perform RAN paging.

[0160] At 6017, the NG-RAN node 602 responds to the AMF 603. This response of 6014 may comprise an NGAP activation response message. This response may indicate that the NG-RAN node 6014 has established radio resources for signalling multicast MBS session data to the UE(s) associated with that NG-RAN that are associated with the MBS multicast service. The NG-RAN 602 may not release the radio connection of a UE that has joined into the multicast session only because no unicast traffic is received for the UE.

[0161]At 6018, the AMF 603 may signal the MB-SMF 607. This response may comprise an Namf_MBSCommunication_N2MessageTransfer Response. [0162] At 6019, the MB-SMF 607 may signal a session modification request to the MB- UPF 606 for forwarding the receiving packet. The MB-UPF 606 may respond to this session modification request with a response.

[0163]This Figure illustrates (at 6016), that all inactive/idle UEs will need to send a service request and transition to an active/connected state in order to received MBS session data.

[0164]This paging procedure is illustrated in respect of Figure 7.

[0165] Figure 7 illustates signaling that may be performed between a UE 701 , a last serving access point 702 of that UE 702, another access point 703, and an AMF 704. The AMF 704 may correspond to the AMF 603 ay 6016 when paging those UEs in the determined set that are in an IDLE connection mode.

[0166]At 7001 , the UE 701 in in an RRC INACTIVE CM mode when a RAN paging trigger event occurs. This may be, for example, incoming downlink signalling on the user plane and/or downlink siganalling on the control plane.

[0167] At 7002, a RAN paging is triggered at the last serving service access point 702. This may be performed either only in at least one cell controlled by the last serving 702 or at both the at least one cell controlled by the last serving access point 702 and at least one cell controlled by the another access point 703.

[0168] In this latter case, the last serving access point 702 signals the another access point 703. This signalling may be effected by an Xn RAN Paging in cells controlled by the another access point. The another access point 703 may be configured to the UE in the RAN-based Notification Area (RNA).

[0169]At 7004, the UE 701 is paged. This paging of 7004 may comprise a temporary identifier. For example, this paging of 7004 may comprise an Inactive-Radio Network Temporary Identifier (l-RNTI).

[0170]An l-RNTI is applicable to the RRC Inactive State. In contrast to other RNTIs, the l-RNTI is not used to scramble the CRC bits belonging to the PDCCH payload. Instead, the l-RNTI is used to address the UE within RRC signaling message. An I- RNTI can be allocated to a UE within an RRCRelease message when the network moves the UE from RRC Connected to RRC Inactive

[0171]The l-RNTI is used to identify both the UE and the Base Station that hosts the UE context. This allows the UE context to be moved from one Base Station to another Base Station if the UE is under mobility while in RRC Inactive state. [0172] At 7005, assuming the UE 701 was successfully paged at 7004, the UE 701 attempts to resume from RRCJNACTIVE, i.e. the UE 701 requests to transition to the RRC_CONNECTED state.

[0173]The following identifies that it would be useful for RRC inactive UEs to remain in an an RRC inactive state during MBS multicast session activation when transmission mode for inactive reception applies for that MBS multicast session in a cell.

[0174] For clarity throughout the description, the following is applicable to the present disclosure. The state of a multicast session can be active or inactive. Multicast data are only transmitted while the multicast session is active

[0175]A UE may be in a particular Radio Resource Control (RRC) state at any particular time. The RRC state of the UE may be RRCJdle, RRCJnactive, or RRC_connected. The UE may transition between these states.

[0176]The RAN node may be able to set a transmission mode of the multicast session. In particular, the RAN node may be able to set a transmission mode for RRCJnactive reception (e.g., when a receiving UE is in an RRCJnactive state) or transmission mode for RRC. Connected reception (e.g., when a receiving UE is in an RRC_connected state). The transmission mode for RRCJnactive reception may thus allow UEs to be in RRC-inactive state while receiving data of the multicast session. UEs in an RRC-connected state may also receive data of the multicast session when the transmission mode for RRCJnactive reception is used.

[0177]The following is concerned with is a procedure for activating the multicast session that is used when data transmission starts. Further, while there is no multicast data transmission, the transmission mode may be considered irrelevant. However, UEs can still transition to an inactive RRC state while there are no multicast data transmissions.

[0178] The procedure for the activation may depend on the selected transmission mode. For example, for transition mode for connected reception, inactive UEs may be triggered to transition to an RRC connected state. For transmission mode for inactive reception, inactive UEs may be informed about the MBS session activation in a manner that avoids causing RRC inactive state UEs to transition into an RRC connected state.

[0179]To this effect the following provides examples in which, when receiving an NG activation request or an XnAP RAN Multicast Group paging request for a multicast session (which may be indicated using a MBS session identifier, such as discussed above), an access point (e.g., an NG_RAN node) determines for each cell within RAN paging area of UEs within that multicast session whether to use a transmission mode for inactive reception or the transmission mode for connected mode reception. The transmission mode tor inactive reception enables UEs that are in an RRC inactive state to receive data of the MBS session without transitioning to an RRC connected state. The transmission mode tor connected reception requires that UEs are in RRC connected state to receive data of the MBS session.

[0180]When a RAN node has insufficient information about UEs within multicast session in cell, the RAN node may be preconfigured to perform a predetermined course of action. For example, the location of RRC-inactive UEs is not known at cell level. Instead, it is known only for a much larger RAN paging area. However, when UEs are in an RRC-Connected state, their location is then known at cell level, which enables a RAN node to determine at least some UEs within the multicast session are present within a cell. Future determinations may be influenced based on the result of employing this predetermined course of action, such that future determinations may result in a different course of action being performed when the RAN node has insufficient information about UEs within a multicast session in a cell. The predetermined course of action may be dependent on information about UEs and or UE number.

[0181]When the NG RAN node determine to use the transmission mode for connected mode reception, the NG RAN node sends an RAN paging request to the INACTIVE mode UE.

[0182]When the NG RAN node determines to use a transmission mode for inactive reception, the NG RAN node may perform at least one of the following.

[0183]As a first option, the NG RAN node may broadcast, in a radio channel (e.g., in a Multicast Control Channel (MCCH)), that the NG RAN node is transmitting the MBS session. This broadcasting may comprise the identifier identifying the multicast session.

[0184] In a variant to this first option, the NG RAN node also additionally or alternatively signals an MBS session identifier for inactive sessions along with an indication of whether the MBS session is active (or not). This variant may be beneficial when handling mobility for location dependent services, where an MBS session may be active in some areas and inactive in other areas. [0185] In a variant to this first option, the NG RAN node also additionally or alternatively transmits the MBS session ID for UEs within multicast session with transmission mode for connected mode reception and indicates whether to use transmission mode for inactive reception or connected mode reception. This variant may also be beneficial to handle mobility for location dependent services where an MBS session may be active in some areas and inactive in other areas.

[0186] These variants may be effected by, for example, signaling a RAN-initiated paging request to a cell and indicating within that request that the paging if for receiving MBS data via inactive transmission mode. This signalling may request the establishment of shared delivery for the multicast session (when triggered by XnAP RAN Multicast Group paging). The NG RAN may initiate transmitting data, either immediately or when the NG RAN node identifies UEs interested in the multicast session as being present in the cell.

[0187] The NG RAN node may send a request for announcing MBS session activation to at least one neighboring RAN nodes within the RAN notification area of UEs in in the MBS session (multicast group paging area). This may be performed by, for example, using an XnAP RAN Multicast Group paging request.

[0188]The UE may determine whether to receive the data in transmission mode for inactive reception or in transmission mode for connected mode reception based one of the following ways, depending on the variant chosen above.

[0189] For example, the UE may determine whether to receive incoming data in a CONNECTED mode or an INACTIVE mode in dependence on receipt of a broadcasted message, in response to an indication to use a specific transmission mode for inactive reception in a RAN-initiated paging message, and/or in dependence on receiving a broadcasted message that a multicast session is transmitted and no RAN-initiated paging message is subsequently received.

[0190]The UE may subsequently receive MBS data in accordance with its determination. In the variant in which the NG RAN node also transmits an MBS session ID for inactive sessions along with an indication of whether the MBS session is inactive, the UE may start receiving MBS data only when it is indicated that the session is active.

[0191]The presently described system is illustrated with respect to Figure 8.

[0192] Figure 8 illustrates signalling that may be performed between a UE 801 , a first NG RAN node 802, a second NG RAN node 803, and an AMF 804. [0193] At 8001 , the AMF 804 signals an activation request to the first NG RAN 802 in respect of an MBS session. This activation request indicates that data transmission for the MBS multicast session is about to start or resume. This activation request may comprise an identifier of the MBS session (e.g., a TMGI). The NG RAN 802 may have information of UEs served by NG RAN 802 that have requested to receive the multicast service (in other words, the NG RAN 802 may have information of UEs that it serves that have joined the multicast session).

[0194] At 8002, the first NG RAN 802 determines an area for the activation by combining RAN-based Notification Areas (RNAs) of UEs that joined the multicast session, that are in RRC inactive state, and that are being served by the RAN node, and intersecting that combined area with a possible service area of the MBS session being activated. An RNA is defined by 3GPP specifications.

[0195] For cells in the determined activation area, NG RAN 802 determines at 8003 whether to apply a transmission mode for inactive reception of the MBS data or to apply a transmission model for connected reception of the MBS data. This determination may be made independently in respect of each cell. This determination may be made for all cells located within the determined intersected area. As mentioned above, the transmission mode for inactive reception enables UEs in RRCJnactive state to receive data of the multicast session. The transmission mode for connected reception requires that UEs are in RRC-connected state to receive the MBS data, [0196] At 8004, for those cells where it is determined at 8003 to apply the transmission mode for an inactive reception, the first NG RAN 802 signals broadcast information. This broadcast information may comprise the identifier of the multicast session. This broadcast information of 8004 may comprise an indication that the MBS session is active (i.e., that data for the MBS session are being transmitted). In response to the receiving the broadcasted information 8004, the UE 801 prepares to receive of the MBS session while remaining in the RRCJNACTIVE state for receiving the MBS service data.

[0197]At 8005, for those cells determined at 8003 to apply the transmission mode for connected reception, the first NG RAN 802 sends a paging request for the multicast session. This signalling of 8005 may comprise the multicast session identifier. In response to the paging of 8005, the UE 801 may enter a RRC CONNECTED state for receiving the MBS service data. [0198] 8005 to 8009 are steps that may be performed when it is determined that at least part of the determined activation area is served by the second NG RAN 803.

[0199] At 8006, the first NG RAN 802 signals the second NG RAN 803. This signalling of 8006 may be an activation and/or paging request. The signalling of 8006 may comprise the identifier of the MBS session. The signalling of 8006 may comprise an indication of an activation area.

[0200]At 8007, the second NG RAN 803 determines whether to apply a transmission mode for inactive reception of the MBS data or to apply a transmission model for connected reception of the MBS data for the cells within the received activation area. [0201 ] At 8008, for those cells where it is determined at 8007 to apply the transmission mode for an inactive reception, the second NG RAN 803 signals broadcast information. This broadcast information may comprise the identifier of the multicast session. This broadcast information of 8007 may comprise an indication that the MBS session is active. In response to the receiving the broadcasted information 8004, the UE 801 prepares to receive of the MBS session but remains in the RRCJNACTIVE state for receiving the MBS service data.

[0202]At 8009, for those cells determined at 8007 to apply the transmission mode for connected reception, the second NG RAN 803 sends a paging request for the multicast session. This signaling of 8009 may comprise the multicast session identifier. In response to the paging of 8009, the UE 801 may enter a RRC CONNECTED state for receiving the MBS service data.

[0203] Figures 9 and 10 illustrate example operations that may be performed by apparatus described herein. It is understood that these highlight aspects of the above, and that features of the above examples may be combined with these highlighted aspects in certain implementations.

[0204] Figure 9 illustrates operations that may be performed by an apparatus for an access node. The access node may be, for example, a RAN node, such as an NG- RAN node.

[0205]At 901 , the apparatus receive a request for activation of a multicast session.

[0206] At 902, the apparatus determines, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state. [0207] At 903, in response to determining to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, the apparatus signals, for/to at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state.

[0208]When it is determined at 902 to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control CONNECTED state, the apparatus signals, for/to at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control CONNECTED state. The receiving UE may attempt to transition to an RRC CONNECTED state in response to receiving such an indication in order to receive data of the multicast session.

[0209]At 904, the apparatus transmits data of the multicast session in the cell using the determined transmission mode.

[0210]The multicast session may be associated with a service area, and wherein the at least one cell is within the service area.

[0211]The request may be received from a core network function or a neighbouring radio access network node.

[0212] The apparatus may further receive an indication of the service area to activate the multicast session from a neighbouring radio access network node

[0213]The determining at 902 may comprises determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the cell (e.g., if there is a relatively large number of RRC connected UE in the cell (i.e., at least a threshold number), then the transmission mode selected may be a transmission mode for RRC connected mode, while when there is a relatively low number of RRC connected UE in the cell (i.e., less than the threshold number), then the transmission mode selected may be a transmission mode for RRC inactive mode); and a preconfiguration (e.g., what the apparatus is configured to do when it determines that it has insufficient information).

[0214]The signalled indication that the multicast session is activated may comprise an explicit indication indicating whether the multicast session is active or inactive.

[0215]The transmitting the signalled indication may be only performed when the multicast session is active. [0216]The signalled indication may comprise an identifier of the multicast session (e.g., a TMGI).

[0217]The signalling the indication may comprise signalling the indication using a broadcast channel.

[0218]The signalling may comprise signalling a paging request for the multicast session to the user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

[0219]The apparatus may comprise repeatedly signalling said indication that the multicast session is activated while the multicast session is active. This repeated signalling may be periodic. This repeated signalling may be only performed while the multicast session is active (i.e., has become activated).

[0220]The apparatus may be caused to determine area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signal a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each RAN node at least the part of the determined are handled by the RAN node. The request for the activation for the multicast service to the at least neighbouring RAN node may comprise an XnAP RAN Multicast Group paging request.

[0221] Figure 10 illustrates operations that may be performed by an apparatus for a user equipment. The user equipment may be a user equipment discussed above in relation to Figure 10.

[0222] At 1001 , the apparatus receives, from an access point (e.g., the access point of Figure 9), an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state.

[0223] At 1002, the apparatus receives data of the multicast session in the cell using the transmission mode for reception in a Radio Resource Control INACTIVE state.

[0224] Said indication is an explicit indication that indicates whether the multicast session is active or inactive.

[0225] Said indication may be only received when the multicast session is active. [0226]Said indication may comprise an identifier of the multicast session.

[0227]The apparatus may further receive said indication via a broadcast channel. [0228] The apparatus may receive said indication via a Radio Access Network paging request for the multicast session.

[0229] The apparatus may receive said indication that a multicast session is activated while the multicast session is active. The apparatus may receive said indication that a multicast session is activated only while the multicast session is active.

[0230] Figure 2 shows an example of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, gNB, a central unit of a cloud architecture or a node of a core network such as an MME or S-GW, a scheduling entity such as a spectrum management entity, or a server or host, for example an apparatus hosting an NRF, NWDAF, AMF, SMF, UDM/UDR, and so forth. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some examples, base stations comprise a separate control apparatus unit or module. In other examples, the control apparatus can be another network element, such as a radio network controller or a spectrum controller. The control apparatus 200 can be arranged to provide control on communications in the service area of the system. The apparatus 200 comprises at least one memory 201 , at least one data processing unit 202, 203 and an input/output interface 204. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the apparatus. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head. For example, the control apparatus 200 or processor 201 can be configured to execute an appropriate software code to provide the control functions.

[0231] A possible wireless communication device will now be described in more detail with reference to Figure 3 showing a schematic, partially sectioned view of a communication device 300. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is referred to as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Nonlimiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

[0232JA wireless communication device may be for example a mobile device, that is, a device not fixed to a particular location, or it may be a stationary device. The wireless device may need human interaction for communication, or may not need human interaction for communication. As described herein, the terms UE or “user” are used to refer to any type of wireless communication device.

[0233]The wireless device 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3, a transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided, for example, by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the wireless device.

[0234JA wireless device is typically provided with at least one data processing entity 301 , at least one memory 302 and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The user may control the operation of the wireless device by means of a suitable user interface such as keypad 305, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 308, a speaker and a microphone can be also provided. Furthermore, a wireless communication device may comprise appropriate connectors (either wired or' wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

[0235] Figure 4 shows a schematic representation of non-volatile memory media 400a (e.g. computer disc (CD) or digital versatile disc (DVD)) and 400b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 402 which when executed by a processor allow the processor to perform one or more of the steps of the methods of Figure 9 and/or Figure 10, and/or methods otherwise described previously.

[0236] As provided herein, various aspects are described in the detailed description of examples and in the claims. In general, some examples may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although examples are not limited thereto. While various examples may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0237] The examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures, e.g., as in Figure 9 and/or Figure 10, and/or otherwise described previously, may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media (such as hard disk or floppy disks), and optical media (such as for example DVD and the data variants thereof, CD, and so forth).

[0238]The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (AStudy ItemC), gate level circuits and processors based on multicore processor architecture, as nonlimiting examples. [0239] Additionally or alternatively, some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and/or method steps previously described. That circuitry may be provided in the base station and/or in the communications device and/or in a core network entity.

[0240]As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analogue and/or digital circuitry);

(b) combinations of hardware circuits and software, such as:

(i) a combination of analogue and/or digital hardware circuit(s) with software/firmware and

(ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and

(c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0241]This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example integrated device.

[0242]The foregoing description has provided by way of non-limiting examples a full and informative description of some examples. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the claims. However, all such and similar modifications of the teachings will still fall within the scope of the claims.

[0243] In the above, different examples are described using, as an example of an access architecture to which the described techniques may be applied, a radio access architecture based on long term evolution advanced (LTE Advanced, LTE-A) or new radio (NR, 5G), without restricting the examples to such an architecture, however. The examples may also be applied to other kinds of communications networks having suitable means by adjusting parameters and procedures appropriately. Some examples of other options for suitable systems are the universal mobile telecommunications system (UMTS) radio access network (UTRAN), wireless local area network (WLAN or WiFi), worldwide interoperability for microwave access (WiMAX), Bluetooth®, personal communications services (PCS), ZigBee®, wideband code division multiple access (WCDMA), systems using ultra-wideband (UWB) technology, sensor networks, mobile ad-hoc networks (MANETs) and Internet Protocol multimedia subsystems (IMS) or any combination thereof.

[0244] Figure 5 depicts examples of simplified system architectures only showing some elements and functional entities, all being logical units, whose implementation may differ from what is shown. The connections shown in Figure 5 are logical connections; the actual physical connections may be different. It is apparent to a person skilled in the art that the system typically comprises also other functions and structures than those shown in Figure 5.

[0245] The examples are not, however, restricted to the system given as an example but a person skilled in the art may apply the solution to other communication systems provided with necessary properties.

[0246]The example of Figure 5 shows a part of an exemplifying radio access network. For example, the radio access network may support sidelink communications described below in more detail.

[0247] Figure 5 shows devices 500 and 502. The devices 500 and 502 are configured to be in a wireless connection on one or more communication channels with a node 504. The node 504 is further connected to a core network 506. In one example, the node 504 may be an access node such as (e/g)NodeB serving devices in a cell. In one example, the node 504 may be a non-3GPP access node. The physical link from a device to a (e/g)NodeB is called uplink or reverse link and the physical link from the (e/g)NodeB to the device is called downlink or forward link. It should be appreciated that (e/g)NodeBs or their functionalities may be implemented by using any node, host, server or access point etc. entity suitable for such a usage.

[0248]A communications system typically comprises more than one (e/g)NodeB in which case the (e/g)NodeBs may also be configured to communicate with one another over links, wired or wireless, designed for the purpose. These links may be used for signalling purposes. The (e/g)NodeB is a computing device configured to control the radio resources of communication system it is coupled to. The NodeB may also be referred to as a base station, an access point or any other type of interfacing device including a relay station capable of operating in a wireless environment. The (e/g)NodeB includes or is coupled to transceivers. From the transceivers of the (e/g)NodeB, a connection is provided to an antenna unit that establishes bi-directional radio links to devices. The antenna unit may comprise a plurality of antennas or antenna elements. The (e/g)NodeB is further connected to the core network 506 (CN or next generation core NGC). Depending on the deployed technology, the (e/g)NodeB is connected to a serving and packet data network gateway (S-GW +P-GW) or user plane function (UPF), for routing and forwarding user data packets and for providing connectivity of devices to one or more external packet data networks, and to a mobile management entity (MME) or access mobility management function (AMF), for controlling access and mobility of the devices.

[0249] Examples of a device are a subscriber unit, a user device, a user equipment (UE), a user terminal, a terminal device, a mobile station, a mobile device, etc [0250]The device typically refers to a mobile or static device (e.g. a portable or nonportable computing device) that includes wireless mobile communication devices operating with or without an universal subscriber identification module (USIM), including, but not limited to, the following types of devices: mobile phone, smartphone, personal digital assistant (PDA), handset, device using a wireless modem (alarm or measurement device, etc.), laptop and/or touch screen computer, tablet, game console, notebook, and multimedia device. It should be appreciated that a device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network. A device may also be a device having capability to operate in Internet of Things (loT) network which is a scenario in which objects are provided with the ability to transfer data over a network without requiring human-to-human or human-to-computer interaction, e.g. to be used in smart power grids and connected vehicles. The device may also utilise cloud. In some applications, a device may comprise a user portable device with radio parts (such as a watch, earphones or eyeglasses) and the computation is carried out in the cloud.

[0251 ]The device illustrates one type of an apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a device may be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay (self-backhauling relay) towards the base station. The device (or, in some examples, a layer 3 relay node) is configured to perform one or more of user equipment functionalities.

[0252] Various techniques described herein may also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected information and communications technology, ICT, devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals.

[0253] Additionally, although the apparatuses have been depicted as single entities, different units, processors and/or memory units (not all shown in Figure 5) may be implemented.

[0254]5G enables using multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and/or spectrum available. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of data sharing and various forms of machine type applications (such as (massive) machine-type communications (mMTC), including vehicular safety, different sensors and real-time control). 5G is expected to have multiple radio interfaces, e.g. below 6GHz or above 24 GHz, cmWave and mmWave, and also being integrable with existing legacy radio access technologies, such as the LTE. Integration with the LTE may be implemented, at least in the early phase, as a system, where macro coverage is provided by the LTE and 5G radio interface access comes from small cells by aggregation to the LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6GHz - cmWave, 6 or above 24 GHz - cmWave and mmWave). One of the concepts considered to be used in 5G networks is network slicing in which multiple independent and dedicated virtual sub-networks (network instances) may be created within the same infrastructure to run services that have different requirements on latency, reliability, throughput and mobility.

[0255]The LTE network architecture is fully distributed in the radio and fully centralized in the core network. The low latency applications and services in 5G require to bring the content close to the radio which leads to local break out and multi-access edge computing (MEC). 5G enables analytics and knowledge generation to occur at the source of the data. This approach requires leveraging resources that may not be continuously connected to a network such as laptops, smartphones, tablets and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content in close proximity to cellular subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing also classifiable as local cloud/fog computing and grid/mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, autonomic self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and/or latency critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0256]The communication system is also able to communicate with other networks 512, such as a public switched telephone network, or a VoIP network, or the Internet, or a private network, or utilize services provided by them. The communication network may also be able to support the usage of cloud services, for example at least part of core network operations may be carried out as a cloud service (this is depicted in Figure 5 by “cloud” 514). This may also be referred to as Edge computing when performed away from the core network. The communication system may also comprise a central control entity, or a like, providing facilities for networks of different operators to cooperate for example in spectrum sharing.

[0257] The technology of Edge computing may be brought into a radio access network (RAN) by utilizing network function virtualization (NFV) and software defined networking (SDN). Using the technology of edge cloud may mean access node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head or base station comprising radio parts. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. Application of cloudRAN architecture enables RAN real time functions being carried out at or close to a remote antenna site (in a distributed unit, DU 508) and non- real time functions being carried out in a centralized manner (in a centralized unit, CU 510).

[0258] It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent. Some other technology advancements probably to be used are Big Data and all-IP, which may change the way networks are being constructed and managed. 5G (or new radio, NR) networks are being designed to support multiple hierarchies, where Edge computing servers can be placed between the core and the base station or nodeB (gNB). One example of Edge computing is MEC, which is defined by the European Telecommunications Standards Institute. It should be appreciated that MEC (and other Edge computing protocols) can be applied in 4G networks as well.

[0259] 5G may also utilize satellite communication to enhance or complement the coverage of 5G service, for example by providing backhauling. Possible use cases are providing service continuity for machine-to-machine (M2M) or Internet of Things (loT) devices or for passengers on board of vehicles, Mobile Broadband, (MBB) or ensuring service availability for critical communications, and future railway/maritime/aeronautical communications. Satellite communication may utilise geostationary earth orbit (GEO) satellite systems, but also low earth orbit (LEO) satellite systems, in particular mega-constellations (systems in which hundreds of (nano)satellites are deployed). Each satellite in the mega-constellation may cover several satellite-enabled network entities that create on-ground cells. The on-ground cells may be created through an on-ground relay node or by a gNB located on-ground or in a satellite.

[0260]The depicted system is only an example of a part of a radio access system and in practice, the system may comprise a plurality of (e/g)NodeBs, the device may have an access to a plurality of radio cells and the system may comprise also other apparatuses, such as physical layer relay nodes or other network elements, etc. At least one of the (e/g)NodeBs or may be a Home(e/g)nodeB. Additionally, in a geographical area of a radio communication system a plurality of different kinds of radio cells as well as a plurality of radio cells may be provided. Radio cells may be macro cells (or umbrella cells) which are large cells, usually having a diameter of up to tens of kilometers, or smaller cells such as micro-, femto- or picocells. The (e/g)NodeBs of Figure 5 may provide any kind of these cells. A cellular radio system may be implemented as a multilayer network including several kinds of cells. Typically, in multilayer networks, one access node provides one kind of a cell or cells, and thus a plurality of (e/g)NodeBs are required to provide such a network structure.

[0261] For fulfilling the need for improving the deployment and performance of communication systems, the concept of “plug-and-play” (e/g)NodeBs has been introduced. Typically, a network which is able to use “plug-and-play” (e/g)Node Bs, includes, in addition to Home (e/g)NodeBs (H(e/g)nodeBs), a home node B gateway, or HNB-GW (not shown in Figure 5). A HNB Gateway (HNB-GW), which is typically installed within an operator’s network may aggregate traffic from a large number of HNBs back to a core network.

Claims

1 . An apparatus for an access node, the apparatus comprising means for: receiving a request for activation of a multicast session; determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting data of the multicast session in the at least one cell using the determined transmission mode.

2. The apparatus according to claim 1 , wherein the multicast session is associated with a service area, and wherein the at least one cell is within the service area.

3. The apparatus according to any preceding claim, wherein the request is received from a core network function or a neighbouring radio access network node.

4. The apparatus according to any preceding claim, further comprising means for receiving an indication of the service area to activate the multicast session from a neighbouring Radio Access Network node

5. The apparatus according to any preceding claim, wherein the means for determining comprises means for determining in dependence on at least one of the following: a number of Radio Resource Control CONNECTED user equipment configured to receive multicast session in the at least one cell; and preconfiguration.

6. The apparatus according to any preceding claim, wherein the signalled indication that the multicast session is activated comprises an explicit indication indicating whether the multicast session is active or inactive.

7. The apparatus according to any preceding claim, comprising means for transmitting the signalled indication only when the multicast session is active.

8. The apparatus according to any preceding claim, wherein the signalled indication comprises an identifier of the multicast session.

9. The apparatus according to any preceding claim, wherein the means for signalling the indication comprises means for signalling the indication using a broadcast channel.

10. The apparatus according to any of claims 1 to 8, wherein the means for signalling comprises signalling a paging request for the multicast session to the at least one user equipment, wherein the paging request comprises an indication that the transmission mode for reception in a Radio Resource Control INACTIVE state will be used for the multicast session.

1 1 . The apparatus according to any preceding claim, further comprising means for repeatedly signalling said indication that the multicast session is activated while the multicast session is active.

12. The apparatus according to any preceding claims, comprising means for: determining area information representing a first area, the area information indicating an intersection between Radio Access Network, RAN, paging areas of served user equipment associated with the multicast session and the service area of the multicast session; and signalling a request for the activation for the multicast to at least one neighbouring RAN node(s) that serve at least part of the said first area; wherein the request includes for each neighbouring RAN node at least the part of the determined are handled by the neighbouring RAN node

13. The apparatus according to claim 12, wherein the request for the activation for the multicast service to the at least neighbouring RAN node comprises an XnAP RAN Multicast Group paging request.

14. An apparatus for a user equipment, the apparatus comprising means for: receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

15. The apparatus according to claim 14, wherein said indication is an explicit indication that indicates whether the multicast session is active or inactive.

16. The apparatus according to any of claims 14, wherein said indication is only received when the multicast session is active.

17. The apparatus according to any of claims 14 to 16, wherein said indication comprises an identifier of the multicast session.

18. The apparatus according to any of claims 14 to 17, the apparatus further comprising means for receiving said indication via a broadcast channel.

19. The apparatus according to any of claims 14 to 18, the apparatus comprising means for receiving said indication via a Radio Access Network paging request for the multicast session.

20. The apparatus according to any of claims 14 to 19, the apparatus further comprising means for repeatedly receiving said indication that a multicast session is activated while the multicast session is active.

21 . A method for an apparatus for an access node, the method comprising: receiving a request for activation of a multicast session; determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting data of the multicast session in the at least one cell using the determined transmission mode.

22. A method for an apparatus for a user equipment, the method comprising: receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.

23. A computer program product that, when run on an apparatus for an access node, causes the apparatus to perform: receiving a request for activation of a multicast session; determining, for at least one cell, whether to transmit data for the multicast session using a transmission mode for reception in a Radio Resource Control INACTIVE state or using a transmission mode for reception in a Radio Resource Control CONNECTED state; when it is determined to transmit data for the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state, signalling, for at least one user equipment in the at least one cell, an indication that the multicast session is activated and that the transmission mode for reception will be for a Radio Resource Control INACTIVE state; and transmitting data of the multicast session in the at least one cell using the determined transmission mode.

24. A computer program product that, when run on an apparatus for a user equipment, causes the apparatus to perform: receiving, from an access point, an indication that a multicast session is activated and that a transmission mode for reception will be for a Radio Resource Control INACTIVE state; and receiving data of the multicast session using the transmission mode for reception in a Radio Resource Control INACTIVE state.