WO2025168308A1

WO2025168308A1 - Devices, methods, apparatuses, and computer readable media for multicast reception

Info

Publication number: WO2025168308A1
Application number: PCT/EP2025/050784
Authority: WO
Inventors: Ugur Baran ELMALI; Philippe Godin; Subin NARAYANAN; Salman Nadaf; Dariush M. SOLEYMANI; Jarkko Tuomo Koskela
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2024-02-06
Filing date: 2025-01-14
Publication date: 2025-08-14
Anticipated expiration: 2026-08-06
Also published as: GB202401596D0; GB2637930A

Abstract

Disclosed are devices, methods, apparatuses, and computer readable media for multicast reception An example apparatus for a terminal device may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus at least to: receive from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receive from the first cell, a configuration for receiving the multicast service in the RRC inactive state; select to camp in the first cell and enter into the RRC inactive state; determine, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, stay in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

Description

DEVICES, METHODS, APPARATUSES, AND COMPUTER READABLE MEDIA OR MULTICAST RECEPTION

TECHNICAL FIELD

[001] Various example embodiments relate to devices, methods, apparatuses, and computer readable media for multicast reception.

BACKGROUND

[002] Currently, a user equipment (UE) may be enabled to receive a multicast service in radio resource control (RRC) inactive state, which may be referred to as RRC INACTIVE state, for scalability and power saving purposes. A periodically broadcasted multicast control channel (MCCH) in a cell may provide a configuration how the UE in the cell receives the multicast service in the RRC inactive state. For a UE to be able to receive a multicast service in the RRC inactive state in a newly camped cell after cell selection, the UE should first read a system information block 24 (SIB24) of the cell that provides a configuration for a MCCH in the cell, and then detects the periodic MCCH to be aware how to receive the multicast service. Thus, the UE may receive the multicast service in the RRC inactive state without going to RRC connected state. Enabling a UE to receive a multicast service in the RRC inactive state is a per cell decision, therefore, it is possible that the UE would not find the multicast service after reading the MCCH and then reconnect to receive the multicast service in the RRC connected state. It is also possible that the multicast service is not provided in the newly camped cell, because there was no UE that joined the multicast service in the cell before.

SUMMARY

[003] A brief summary of exemplary embodiments is provided below to provide basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define scopes of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a preamble for a more detailed description provided below.

[004] In a first aspect, disclosed is an apparatus for a terminal device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus at least to: receive from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receive from the first cell, a configuration for receiving the multicast service in the RRC inactive state; select to camp in the first cell and enter into the RRC inactive state; determine, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, stay in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[005] In a second aspect, disclosed is an apparatus for a network device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: perform at least one of the following: transmitting to a distributed unit, DU, of the first base station, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[006] In a third aspect, disclosed is an apparatus for a network device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a first distributed unit, DU, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and perform at least one of the following: transmitting to one or more DUs of the first base station other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[007] In a fourth aspect, disclosed is an apparatus for a network device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a CU CP of a second base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and transmit to one or more DUs of the first base station, the list of identifiers of cells with the information.

[008] In a fifth aspect, disclosed is an apparatus for a network device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: receive from a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and broadcast the list of identifiers of cells with the information towards terminal devices served by the DU of the first base station. [009] In a sixth aspect, disclosed is an apparatus for a network device. The apparatus may include at least one processor and at least one memory. The at least one memory may store instructions that, when executed by the at least one processor, may cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: transmit to a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH.

[0010] In a seventh aspect, disclosed is a method performed by an apparatus for a terminal device. The method may comprise: receiving from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receiving from the first cell, a configuration for receiving the multicast service in the RRC inactive state; selecting to camp in the first cell and entering into the RRC inactive state; determining, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, staying in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[0011] In an eighth aspect, disclosed is a method performed by an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The method may comprise: performing at least one of the following: transmitting to a distributed unit, DU, of the first base station, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0012] In a ninth aspect, disclosed is a method performed by an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The method may comprise: receiving from a first distributed unit, DU, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and performing at least one of the following: transmitting to one or more DUs of the first base station other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0013] In a tenth aspect, disclosed is a method performed by an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The method may comprise: receiving from a CU CP of a second base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and transmitting to one or more DUs of the first base station, the list of identifiers of cells with the information.

[0014] In an eleventh aspect, disclosed is a method performed by an apparatus, functioning as a distributed unit, DU, of a first base station, for a network device. The method may comprise: receiving from a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and broadcasting the list of identifiers of cells with the information towards terminal devices served by the DU of the first base station.

[0015] In a twelfth aspect, disclosed is a method performed by an apparatus, functioning as a distributed unit, DU, of a first base station, for a network device. The method may comprise: transmitting to a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH. [0016] In a thirteenth aspect, disclosed is an apparatus for a terminal device. The apparatus for the terminal device may comprise: means for receiving from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; means for receiving from the first cell, a configuration for receiving the multicast service in the RRC inactive state; means for selecting to camp in the first cell and entering into the RRC inactive state; means for determining, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and means for based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, staying in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[0017] In a fourteenth aspect, disclosed is an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The apparatus for the network device may comprise: means for performing at least one of the following: transmitting to a distributed unit, DU, of the first base station, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0018] In a fifteenth aspect, disclosed is an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The apparatus for the network device may comprise: means for receiving from a first distributed unit, DU, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means for performing at least one of the following: transmitting to one or more DUs of the first base station other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0019] In a sixteenth aspect, disclosed is an apparatus, functioning as a centralized unit, CU, control plane, CP, of a first base station, for a network device. The apparatus for the network device may comprise: means for receiving from a CU CP of a second base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means for transmitting to one or more DUs of the first base station, the list of identifiers of cells with the information.

[0020] In a seventeenth aspect, disclosed is an apparatus, functioning as a distributed unit, DU, of a first base station, for a network device. The apparatus for the network device may comprise: means for receiving from a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means for broadcasting the list of identifiers of cells with the information towards terminal devices served by the DU of the first base station.

[0021] In an eighteenth aspect, disclosed is an apparatus, functioning as a distributed unit, DU, of a first base station, for a network device. The apparatus for the network device may comprise: means for transmitting to a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH.

[0022] In a nineteenth aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a terminal device, may cause the apparatus at least to: receive from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receive from the first cell, a configuration for receiving the multicast service in the RRC inactive state; select to camp in the first cell and enter into the RRC inactive state; determine, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, stay in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[0023] In a twentieth aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a network device, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: perform at least one of the following: transmitting to a distributed unit, DU, of the first base station, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0024] In a twenty first aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a network device, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a first distributed unit, DU, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and perform at least one of the following: transmitting to one or more DUs of the first base station other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

[0025] In a twenty second aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a network device, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a CU CP of a second base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and transmit to one or more DUs of the first base station, the list of identifiers of cells with the information.

[0026] In a twenty third aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a network device, cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: receive from a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and broadcast the list of identifiers of cells with the information towards terminal devices served by the DU of the first base station.

[0027] In a twenty fourth aspect, a computer readable medium is disclosed. The computer readable medium may comprise program instructions that, when executed by an apparatus for a network device, cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: transmit to a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH. [0028] Other features and advantages of the example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings. [0030] FIG. 1A shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure.

[0031] FIG. IB shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure.

[0032] FIG. 2A shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure.

[0033] FIG. 2B shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure.

[0034] FIG. 3 shows a flow chart illustrating an example method 300 for multicast reception according to the example embodiments of the present disclosure.

[0035] FIG. 4 shows a flow chart illustrating an example method 400 for multicast reception according to the example embodiments of the present disclosure.

[0036] FIG. 5 shows a flow chart illustrating an example method 500 for multicast reception according to the example embodiments of the present disclosure.

[0037] FIG. 6 shows a flow chart illustrating an example method 600 for multicast reception according to the example embodiments of the present disclosure.

[0038] FIG. 7 shows a flow chart illustrating an example method 700 for multicast reception according to the example embodiments of the present disclosure.

[0039] FIG. 8 shows a flow chart illustrating an example method 800 for multicast reception according to the example embodiments of the present disclosure.

[0040] FIG. 9 shows a block diagram illustrating an example device 900 for multicast reception according to the example embodiments of the present disclosure.

[0041] FIG. 10 shows a block diagram illustrating an example device 1000 for multicast reception according to the example embodiments of the present disclosure.

[0042] FIG. 11 shows a block diagram illustrating an example device 1100 for multicast reception according to the example embodiments of the present disclosure.

[0043] FIG. 12 shows a block diagram illustrating an example device 1200 for multicast reception according to the example embodiments of the present disclosure.

[0044] FIG. 13 shows a block diagram illustrating an example device 1300 for multicast reception according to the example embodiments of the present disclosure. [0045] FIG. 14 shows a block diagram illustrating an example device 1400 for multicast reception according to the example embodiments of the present disclosure.

[0046] FIG. 15 shows a block diagram illustrating an example apparatus 1500 for multicast reception according to the example embodiments of the present disclosure.

[0047] FIG. 16 shows a block diagram illustrating an example apparatus 1600 for multicast reception according to the example embodiments of the present disclosure.

[0048] FIG. 17 shows a block diagram illustrating an example apparatus 1700 for multicast reception according to the example embodiments of the present disclosure.

[0049] FIG. 18 shows a block diagram illustrating an example apparatus 1800 for multicast reception according to the example embodiments of the present disclosure.

[0050] FIG. 19 shows a block diagram illustrating an example apparatus 1900 for multicast reception according to the example embodiments of the present disclosure.

[0051] FIG. 20 shows a block diagram illustrating an example apparatus 2000 for multicast reception according to the example embodiments of the present disclosure.

[0052] Throughout the drawings, same or similar reference numbers indicate same or similar elements. A repetitive description on the same elements would be omitted.

DETAILED DESCRIPTION

[0053] Herein below, some example embodiments are described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known circuits, techniques and components are shown in block diagram form to avoid obscuring the described concepts and features.

[0054] Currently, if a UE is configured to receive a multicast service in RRC inactive state and cannot find a SIB24 in a newly camped cell, the UE reconnects to the cell. Further, if a source cell operates a multicast service without a MCCH, and in the source cell a UE receives the multicast service in the RRC inactive state, when the UE in the RRC inactive state selects a target cell different from the source cell, the UE is not aware how to determine the target cell operates the multicast service with a MCCH or without a MCCH and is not aware what corresponding behavior should be. In addition, if a UE receives a group paging message that indicates the UE to stay in the RRC inactive state and receive a multicast service, the UE should read a SIB24 and a MCCH, and thus in a network or a cell without the MCCH, the UE will go back to RRC connected state.

[0055] Example embodiments of the present disclosure provide a solution for multicast reception. According to the example embodiments of the present disclosure, a UE is able to determine that a network or a cell operates a multicast service with a MCCH or without a MCCH and the UE is able to adapt to different operations in RRC inactive state based on such determination.

[0056] FIG. 1 A shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure. Referring to the FIG. 1A, a UE 110 may represent any terminal device in a network, and a first cell 150 may represent the cell serving the UE 110 in the network.

[0057] Initially, the UE 110 is in RRC connected state and connected to the first cell 150. In this state, the UE 110 receives a multicast service, e.g. multicast service A, from the first cell 150. The multicast service may also be referred to as multicast session.

[0058] Then, the base station (BS), e.g. the next Generation Node B (gNB), supporting the first cell 150 may decide to release the UE 110 to RRC inactive state, due to e.g. network congestion. [0059] The UE 110 may receive from the first cell 150, a configuration 152 allowing the UE 110 to receive the multicast service A in the RRC inactive state. With the configuration 152, the UE 110 is allowed to receive the multicast service A in the RRC inactive state. In some embodiments, the configuration 152 may be a one-bit indicator indicating whether the UE 110 is allowed to receive the multicast service A in the RRC inactive state.

[0060] The UE 110 may also receive from the first cell 150, a configuration 154 for receiving the multicast service A in the RRC inactive state. With the configuration 154, the UE 110 is aware how to receive the multicast service A in the RRC inactive state. According to the wording in the standard specifications, the configuration 152 may be comprised in multicastConfiglnactive that indicates multicast service(s) that UEs are allowed to receive in the RRC inactive state in the serving cell. If the multicast service A is comprised in the multicastConfiglnactive, the UE 110 may determine that it is allowed to receive the multicast service A in the RRC inactive state. Optionally, multicastConfiglnactive may further comprise the corresponding configuration (e.g. MBSMulticastConfiguration-rl8) for the multicast service(s). This information element may include configurations for each multicast service provided in the cell, e.g. the configuration 154 for the multicast service A. The UE 110 may read the configuration of the multicast service A from this information element so that the UE 110 is aware of the configuration to receive the multicast service A in the RRC inactive state. In some embodiments, the information element (MBSMulticastConfiguration-rl8) comprises a temporary mobile group identity (TMGI) of the multicast service A which indicates to the UE 110 that the UE 110 is allowed to receive a multicast service A in the RRC inactive state.

[0061] The UE 110 may receive the configuration 152 and the configuration 154 together or separately. In some embodiments, the UE 110 may receive the configuration 152 and the configuration 154 via the RRC release with suspend message which releases the UE 110 to enter into the RRC inactive state. In some embodiments, the UE 110 may receive one of the configuration 152 and the configuration 154 before receiving the RRC release with suspend message and receive the other via the RRC release with suspend message. In some embodiments, the configuration 154 may be provided before the RRC release with suspend message, and the allowance may be indicated via the configuration 152 in the RRC release with suspend message. This way, the configuration may be made beforehand and activated with low signaling in connection with the RRC release with suspend message. In some embodiments, the allowance is indicated via the configuration 152 before the RRC release with suspend to make the UE 110 aware of the allowance, and the configuration 154 may be provided in the RRC release with suspend message. This way, the configuration 154 may take into account the conditions at the time of the RRC release with suspend message. Alternatively, the UE 110 may receive the configuration 152 and the configuration 154 separately before receiving the RRC release with suspend message.

[0062] Before entering into the RRC inactive state, in an operation 112, the UE 110 may select to camp in the first cell 150. Then, in the RRC inactive state, in an operation 114, the UE 110 may determine, implicitly based on available information on the first cell 150, whether the first cell 150 operates the multicast service A without a MCCH. The MCCH in the first cell 150 is referred to as first MCCH in the present disclosure. The implicit determining may also be referred to as assuming.

[0063] In some embodiments, the available information may be some condition, and if the condition is satisfied, the UE 110 may determine implicitly that the first cell 150 operates the multicast service A without the first MCCH.

[0064] In some embodiments, in an operation 116, the UE 110 may detect whether the first cell 150 operates without a SIB24. For example, the UE 110 may read a SIB1 of the first cell 150 and detect that the SIB1 does not include information about the SIB24. In this case, the UE 110 may detect that the first cell 150 operates without the SIB24 and determine implicitly that the first cell 150 operates the multicast service A without the first MCCH. In some embodiments, in this case, the UE 110 may determine implicitly that in the first cell 150 operation without the first MCCH is not a per service decision, i.e. not just for the multicast service A.

[0065] In some embodiments, in an operation 118, the UE 110 may detect whether the first cell 150 operates with a SIB24 without a configuration for the first MCCH. For example, the UE 110 may read a SIB 1 of the first cell 150, detect the SIB 24 based on the information about the SIB24, and detect that the SIB24 does not include a configuration for the first MCCH. In this case, the UE 110 may detect that the first cell 150 operates the SIB24 without a configuration for the first MCCH and determine implicitly that the first cell 150 operates the multicast service A without the first MCCH. In some embodiments, in this case, the UE 110 may determine implicitly that in the first cell 150 operation without the first MCCH is not a per service decision, i.e. not just for the multicast service A, but also for other or even all the possible multicast services in the network.

[0066] In some embodiments, in an operation 120, the UE 110 may detect, without a configuration for the multicast service A, whether the first cell 150 operates with the first MCCH. For example, the UE 110 may read a SIB such as the SIB24, detect a configuration of the first MCCH based on the information about the first MCCH in the SIB24, and detect that the first MCCH does not include a configuration for the multicast service A. In this case, the UE 110 may detect that the first cell 150 operates with the first MCCH without a configuration for the multicast service A and determine implicitly from this information that the first cell 150 operates the multicast service A without the first MCCH. In some embodiments, in this case, the UE 110 may determine implicitly that in the first cell 150 operation without the first MCCH is a per service decision, i.e. for some specific multicast service such as the multicast service A. Accordingly, the first cell may operate one multicast service with the first MCCH and another multicast service without the MCCH.

[0067] In some embodiments, the first cell 150 is in a radio access network (RAN), the multicast service A is one of a plurality of multicast services in the RAN, in an operation 122, the UE 110 may determine whether the first cell 150 or the RAN operates the multicast service A without a MCCH or the plurality of multicast services without a MCCH. For example, in case the UE 110 determines implicitly that the first cell 150 operates the multicast service A without the first MCCH, the UE 110 may determine that the RAN operates the multicast service A without a MCCH, the first cell 150 operates the multicast service(s), provided in the first cell 150, without the first MCCH, and/or the RAN operates the plurality of multicast services without a MCCH. Alternatively or additionally, the first cell 150 may be in a public land mobile network (PLMN), and in case the UE 110 determines implicitly that the first cell 150 operates the multicast service A without the first MCCH, the UE 110 may determine that the PLMN operates the multicast service A without a MCCH. In such an embodiment, the service RAN or PLMN may employ a global policy for a single multicast service or for all multicast services. In either case, upon detecting a cell providing the multicast service(s) without an MCCH, the UE 110 may implicitly determine that the other cells of the RAN or PLMN employ the same policy for the particular multicast service(s).

[0068] Then, in an operation 124, the UE 110 may, based on the configurations 152 and 154, the available information on the first cell 150 and in the operation 114 determining that the first cell 150 operates the multicast service A without the first MCCH, stay in the RRC inactive state in the first cell 150 to receive the multicast service Ain the RRC inactive state. Thus, the UE 110 may receive the multicast service A without connecting to the first cell 150.

[0069] In some embodiments, the UE 110 may receive from the first cell 150, an indication indicting the UE 110 to stop monitoring radio network temporary identifier (RNTI) for the multicast service A e.g. via the RRC release with suspend message or via a MCCH. Upon receiving the stop monitoring RNTI indication, in an operation 126, the UE 110 does not expect to receive the multicast service Aright now in the RRC inactive state and waits for a group paging message. [0070] In some embodiments, the UE 110 does not perform the operation 114 after entering into the RRC inactive state and before receiving a group paging message. If the UE 110 receives from the first cell 150, a group paging message 156 indicating the UE 110 to stay in the RRC inactive state to receive the multicast service A, the UE 110 may perform the operation 114 and determine that the first cell 150 operates the multicast service A without the first MCCH. Then, in the operation 124, the UE 110 may, based on the received group paging message, stay in the RRC inactive state to receive the multicast service A. Such group paging message 156 may be referred to as enhanced group paging message.

[0071] In some embodiments, the UE 110 may determine that the first cell 150 operates the multicast service A without the first MCCH in the operation 114 and stay in the RRC inactive state in the operation 124. The UE 110 may start a pre-configured timer indicating the maximum duration of being without the first MCCH or count the number of occasions of being without the first MCCH, which may be the number of times where the UE 110 expects SIB24 or the first MCCH. The timer or the maximum number of such occasions may be pre-configured via an RRC signaling message. The UE 110, upon expiring of the timer or reaching the maximum number of such occasions, may change to RRC idle or RRC connected state.

[0072] FIG. IB shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure. Referring to the FIG. IB, after the UE 110 first selects to camp in the first cell 150 in the operation 112 and enters into the RRC inactive state, in an operation 130, the UE 110 may perform a cell reselection to a second cell 170 different from the first cell 150 in the RRC inactive state. The reselection may refer to a scenario where the UE 110 first selects the first cell 150 and then reselects the second cell 170. The UE 110 may perform the operation 130 after the operation 112 or other operation shown in the FIG. 1 A behind the operation 112.

[0073] Upon performing the cell reselection to the second cell 170 in the RRC inactive state, in an operation 132, the UE 110 may determine whether the second cell 170 operates the multicast service A without a MCCH. The MCCH in the second cell 170 is referred to as second MCCH in the present disclosure.

[0074] In some embodiments, in an operation 134, the UE 110 may determine that the second cell 170 operates the multicast service A without the second MCCH based on the determination that the first cell 150 operates the multicast service A without the first MCCH. That is, since the first cell 150 operates the multicast service A without the first MCCH, the UE 110 may assume that the second cell 170 also operates the multicast service A without the second MCCH.

[0075] In some embodiments, in an operation 136, the UE 110 may determine that the second cell 170 operates the multicast service A with the second MCCH. In some embodiments, the UE 110 may assume a MCCH is provided in neighbor cells, e.g. the second cell 170, regardless how source cell, e.g. the first cell 150, operates.

[0076] In some embodiments, the UE 110 may receive from the first cell 150, information 160 whether the second cell 170 operates the multicast service A with the second MCCH or without the second MCCH. Thus the UE 110 may determine whether the second cell 170 operates the multicast service A without the second MCCH based on the information 160.

[0077] In some embodiments, the UE 110 may receive from the first cell 150, a list of identifiers (IDs) of cells, with information 162 whether the cells operate with a MCCH or without a MCCH. The list of IDs of cells may be referred to as cell ID list. In some embodiments, the information 162 may concern the cells in a RAN notification area (RNA) where the UE 110 is configured to camp in the RRC inactive state without notifying the network. In some embodiments, the information 162 may concern the cells in a particular RAN. Thus the UE 110 may determine whether the second cell 170 operates the multicast service A without the second MCCH based on the information 162.

[0078] In some embodiments, the UE 110 may receive the information 160 and/or the cell ID list with the information 162 via the RRC release with suspend message and/or via the first MCCH.

[0079] Based on determining that the second cell 170 operates the multicast service A with the second MCCH, in an operation 138, the UE 110 may decide to stay in the RRC inactive state. The UE 110 may try to read a SIB24 in the second cell 170, get information about the second MCCH, and receive the configuration of the multicast service A based on the second MCCH.

[0080] Alternatively, based on determining that the second cell 170 operates the multicast service A without the second MCCH, in an operation 140, the UE 110 may decide to connect to the second cell 170. In some embodiments, the UE 110 may decide to connect to the second cell 170 directly, for example, the UE 110 does not read a SIB24 or expect reception of the SIB24 or the second MCCH.

[0081] In some embodiments, in an operation 142, the UE 110 may connect to the second cell 170 without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell 170 operates the multicast service A without the second MCCH, and to stop monitoring RNTI is not indicated for one or more multicast services that the UE 110 is configured to receive in the RRC inactive state. For example, if the second cell 170 operates the multicast service A without the second MCCH, and to stop monitoring RNTI is not indicated for any multicast service that the UE 110 is configured to receive in the RRC inactive state, the UE 110 may connect to the second cell 170 directly and does not need to try decoding the SIB24.

[0082] As described in the example embodiments above, the cell 150 may transmit to the UE 110 the information 160 whether the second cell 170 operates the multicast service A with the second MCCH or without the second MCCH or the cell ID list with the information 162 whether cells operate the multicast service A with a MCCH or without a MCCH, which may be realized based on information exchange between the neighboring BSs.

[0083] FIG. 2A shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure. Referring to the FIG. 2 A, a BS 210 includes a centralized unit (CU) control plane (CP) 215 and a distributed unit (DU) 212, and the DU 212 represents any DU of the BS 210. ABS 230 includes a CU CP 235 and DU 232, and the DU 232 represents any DU of the BS 230. The BS 210 and the BS 230 represent any two BSs in a RAN. [0084] In some embodiments, the CU CP 215 may be aware whether the cells supported by the DUs hosted by the BS 210 operate with a MCCH or without a MCCH. In some embodiments, the operation administration and maintenance (0AM) in the core network (CN) may configure the BS 210 with the information whether cells in the RAN operate with a MCCH or without a MCCH. The information may be per multicast service or common to multicast services.

[0085] The CU CP 215 may transmit to the DU 212, a list 220 of IDs of cells, with information 222 whether the cells operate with a MCCH or without a MCCH. The list 220 of IDs of cells may also referred to as cell ID list 220. The information 222 may be or include the information 162 or the information 160, and the cell ID list 220 may include the cells the information 162 or the information 160 concerns. The cell ID list 220 with the information 222 may be transmitted via a Fl application protocol (F1AP) multicast and broadcast system (MBS) common configuration request message, via a multicast context modification request or via any other suitable Fl AP message.

[0086] In some embodiments, the information 222 may concern cells belonging to the DU 212. Alternatively or additionally, in some embodiments, the information 222 may concern cells belonging to another DU of the BS 210. Alternatively or additionally, in some embodiments, the information 222 may concern cells belonging to another BS.

[0087] Receiving the cell ID list 220 with the information 222, in an operation 224, the DU 212 may broadcast the cell ID list 220 with the information 222 towards terminal devices served by the DU 212. The DU 212 may also update its broadcast information based on the received cell ID list 220 with the information 222.

[0088] Alternatively or additionally, the CU CP 215 may transmit to the CU CP 235, the cell ID list 220 with the information 222. The cell ID list 220 with the information 222 may be transmitted via an Xn RAN configuration update message, via an Xn setup message or via any other suitable Xn application protocol (XnAP) message.

[0089] Receiving the cell ID list 220 with the information 222, the CU CP 235 may transmit to the DU 232, the cell ID list 220 with the information 222 via e.g. a F1AP message. Then, in an operation 240, the DU 232 may broadcast the cell ID list 220 with the information 222 towards terminal devices served by the DU 232. The DU 232 may also update its broadcast information based on the received cell ID list 220 with the information 222.

[0090] FIG. 2B shows an exemplary sequence diagram for multicast reception according to the example embodiments of the present disclosure. Referring to the FIG. 2B, a BS 250 includes a CU CP 255, a DU 252 and a DU 256. The DU 252 and the DU 256 represent any two DUs of the BS 250. ABS 270 includes a CU CP 275 and one or more DUs (not shown). The BS 250 and the BS 270 represent any two BSs in a RAN.

[0091] In some embodiments, the DU 252 may decide which cell(s) operate(s) with a MCCH or without a MCCH and initiate the information exchange. In some embodiments, the DU 252 may transmit to the CU CP 255, the cell ID list 220 with the information 222, via e.g. a F1AP message. In some embodiments, the cell ID list 220 and the information 222 may concern the cells supported by the DU 252. [0092] Receiving the cell ID list 220 with the information 222, in some embodiments, in an operation 260, the CU CP 255 may configure UEs with the cell ID list 220 with the information 222 via e.g. a RRC reconfiguration message or via a RRC release with suspend message.

[0093] Alternatively or additionally, in some embodiments, the CU CP 255 may transmit to one or more DUs e.g. the DU 256 of the BS 250 other than the DU 252, the cell ID list 220 with the information 222 via, e.g. a F1AP message. The DU 256 may broadcast the cell ID list 220 with the information 222 towards UEs served by the DU 256 and/or update its broadcast information.

[0094] Alternatively or additionally, in some embodiments, the CU CP 255 may transmit to the CU CP 275, the cell ID list 220 with the information 222 via, e.g. an XnAP message.

[0095] Receiving the cell ID list 220 with the information 222, in an operation 262, the CU CP 275 may transmit the cell ID list 220 with the information 222 to one or more DUs of the BS 270 and/or update its broadcast information.

[0096] According to the example embodiments of the present disclosure, multicast services can be received in RRC inactive state without using a MCCH. The example embodiments of the present disclosure provide an efficient operation, e.g., avoiding unnecessary connections to the network.

[0097] Further, the example embodiments of the present disclosure can provide solutions for different possible cases of operation without a MCCH, e.g., operation without a MCCH per cell, operation without a MCCH per multicast service, or operation without a MCCH per PLMN.

[0098] Moreover, the example embodiments of the present disclosure can provide solutions for different possible indications towards UEs regarding behavior after cell reselection. In addition, the example embodiments of the present disclosure can provide solutions for operations where a CU or a DU may be configured to operate with a MCCH or without a MCCH.

[0099] FIG. 3 shows a flow chart illustrating an example method 300 for multicast reception according to the example embodiments of the present disclosure. The example method 300 may be performed for example by an apparatus for a terminal device such as the UE 110 above mentioned.

[00100] Referring to the FIG. 3, the example method 300 may comprise: an operation 310 of receiving from a first cell, a configuration allowing the apparatus to receive a multicast service in RRC inactive state; an operation 320 of receiving from the first cell, a configuration for receiving the multicast service in the RRC inactive state; an operation 330 of selecting to camp in the first cell and entering into the RRC inactive state; an operation 340 of determining, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first MCCH; and an operation 350 of based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, staying in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[00101] Details of the operation 310 have been described in the above descriptions with respect to at least the configuration 152, and repetitive descriptions thereof are omitted here.

[00102] Details of the operation 320 have been described in the above descriptions with respect to at least the configuration 154, and repetitive descriptions thereof are omitted here.

[00103] Details of the operation 330 have been described in the above descriptions with respect to at least the operation 112, and repetitive descriptions thereof are omitted here.

[00104] Details of the operation 340 have been described in the above descriptions with respect to at least the operation 114, and repetitive descriptions thereof are omitted here.

[00105] Details of the operation 350 have been described in the above descriptions with respect to at least the operation 124, and repetitive descriptions thereof are omitted here.

[00106] In some embodiments, the example method 300 may comprise: determining implicitly that the first cell operates the multicast service without the first MCCH in case at least one of the following is satisfied: detecting that the first cell operates without a SIB24, detecting that the first cell operates with a SIB24 without a configuration for the first MCCH, or detecting that the first cell operates with the first MCCH without a configuration for the multicast service. The more details have been described in the above descriptions with respect to at least the operation 116, the operation 118 and the operation 120, and repetitive descriptions thereof are omitted here. [00107] In some embodiments, the first cell is in a RAN, the multicast service is one of a plurality of multicast services in the RAN, and the example method 300 may comprise: determining whether the first cell or the RAN operates the multicast service without a MCCH or the plurality of multicast services without a MCCH. The more details have been described in the above descriptions with respect to at least the operation 122, and repetitive descriptions thereof are omitted here.

[00108] In some embodiments, the example method 300 may comprise: receiving from the first cell, a group paging message indicating the apparatus to stay in the RRC inactive state to receive the multicast service; and based on the received group paging message, staying in the RRC inactive state to receive the multicast service. The more details have been described in the above descriptions with respect to at least the group paging message 156 and the operation 124, and repetitive descriptions thereof are omitted here.

[00109] In some embodiments, the example method 300 may comprise: upon performing a cell reselection to a second cell different from the first cell in the RRC inactive state, determining whether the second cell operates the multicast service without a second MCCH; and based on determining that the second cell operates the multicast service without the second MCCH, deciding to connect to the second cell, or based on determining that the second cell operates the multicast service with the second MCCH, deciding to stay in the RRC inactive state. The more details have been described in the above descriptions with respect to at least the operation 130, the operation 132 and the operations 138 and 140, and repetitive descriptions thereof are omitted here.

[00110] In some embodiments, the example method 300 may comprise: determining that the second cell operates the multicast service without the second MCCH based on the determination that the first cell operates the multicast service without the first MCCH. The more details have been described in the above descriptions with respect to at least the operation 134, and repetitive descriptions thereof are omitted here.

[00111] In some embodiments, the example method 300 may comprise: determining that the second cell operates the multicast service with the second MCCH. The more details have been described in the above descriptions with respect to at least the operation 136, and repetitive descriptions thereof are omitted here.

[00112] In some embodiments, the example method 300 may comprise: receiving from the first cell, information whether the second cell operates the multicast service with the second MCCH or without the second MCCH. The more details have been described in the above descriptions with respect to at least the information 160, and repetitive descriptions thereof are omitted here. [00113] In some embodiments, the example method 300 may comprise: receiving from the first cell, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH. The more details have been described in the above descriptions with respect to at least the information 162, and repetitive descriptions thereof are omitted here.

[00114] In some embodiments, the example method 300 may comprise: receiving the information or the list of identifiers of cells with the information via a RRC release with suspend message or via the first MCCH. The more details have been described in the above descriptions with respect to at least the information 160 and the information 162, and repetitive descriptions thereof are omitted here.

[00115] In some embodiments, the example method 300 may comprise: connecting to the second cell without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell operates the multicast service without the second MCCH, and to stop monitoring RNTI is not indicated for one or more multicast services that the apparatus is configured to receive in the RRC inactive state. The more details have been described in the above descriptions with respect to at least the operation 142, and repetitive descriptions thereof are omitted here.

[00116] FIG. 4 shows a flow chart illustrating an example method 400 for multicast reception according to the example embodiments of the present disclosure. The example method 400 may be performed for example by an apparatus for a network device such as the CU CP 215 of the BS 210 as the first BS above mentioned.

[00117] Referring to the FIG. 4, the example method 400 may comprise: an operation 410 of performing at least one of the following: transmitting to a DU of the first BS, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00118] Details of the operation 410 have been described in the above descriptions with respect to at least the cell ID list 220 with the information 222 in the FIG. 2A, and repetitive descriptions thereof are omitted here.

[00119] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first base station, cells belonging to another DU of the first base station, or cells belonging to another base station. The more details have been described in the above descriptions with respect to at least the information 222, and repetitive descriptions thereof are omitted here.

[00120] FIG. 5 shows a flow chart illustrating an example method 500 for multicast reception according to the example embodiments of the present disclosure. The example method 500 may be performed for example by an apparatus for a network device such as the CU CP 255 of the BS 250 as the first BS above mentioned.

[00121] Referring to the FIG. 5, the example method 500 may comprise: an operation 510 of receiving from a first DU of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and an operation 520 of performing at least one of the following: transmitting to one or more DUs of the first BS other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00122] Details of the operation 510 and the operation 520 have been described in the above descriptions with respect to at least the cell ID list 220 with the information 222 in the FIG. 2B, and repetitive descriptions thereof are omitted here.

[00123] FIG. 6 shows a flow chart illustrating an example method 600 for multicast reception according to the example embodiments of the present disclosure. The example method 600 may be performed for example by an apparatus for a network device such as the CU CP 235 of the BS 230 as the first BS above mentioned.

[00124] Referring to the FIG. 6, the example method 600 may comprise: an operation 610 of receiving from a CU CP of a second BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and an operation 620 of transmitting to one or more DUs of the first BS, the list of identifiers of cells with the information.

[00125] Details of the operation 610 and the operation 620 have been described in the above descriptions with respect to at least the cell ID list 220 with the information 222 in the FIG. 2A, and repetitive descriptions thereof are omitted here.

[00126] FIG. 7 shows a flow chart illustrating an example method 700 for multicast reception according to the example embodiments of the present disclosure. The example method 700 may be performed for example by an apparatus for a network device such as the DU 212 of the BS 210 as the first BS above mentioned.

[00127] Referring to the FIG. 7, the example method 700 may comprise: an operation 710 of receiving from a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and an operation 720 of broadcasting the list of identifiers of cells with the information towards terminal devices served by the DU of the first BS.

[00128] Details of the operation 710 have been described in the above descriptions with respect to at least the cell ID list 220 with the information 222 in the FIG. 2A, and repetitive descriptions thereof are omitted here.

[00129] Details of the operation 720 have been described in the above descriptions with respect to at least the operation 224 in the FIG. 2A, and repetitive descriptions thereof are omitted here. [00130] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first BS, cells belonging to another DU of the first BS, or cells belonging to another BS. The more details have been described in the above descriptions with respect to at least the information 222, and repetitive descriptions thereof are omitted here.

[00131] FIG. 8 shows a flow chart illustrating an example method 800 for multicast reception according to the example embodiments of the present disclosure. The example method 800 may be performed for example by an apparatus for a network device such as the DU 252 of the BS 250 as the first BS above mentioned.

[00132] Referring to the FIG. 8, the example method 800 may comprise: an operation 810 of transmitting to a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH.

[00133] Details of the operation 810 have been described in the above descriptions with respect to at least the cell ID list 220 with the information 222 in the FIG. 2B, and repetitive descriptions thereof are omitted here.

[00134] FIG. 9 shows a block diagram illustrating an example device 900 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a terminal device such as the UE 110 in the above examples.

[00135] As shown in the FIG. 9, the example device 900 may include at least one processor 910 and at least one memory 920 that may store instructions 930. The instructions 930, when executed by the at least one processor 910, may cause the device 900 at least to perform the example method 300 described above.

[00136] In various example embodiments, the at least one processor 910 in the example device 900 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 910 may also include at least one other circuitry or element not shown in the FIG. 9.

[00137] In various example embodiments, the at least one memory 920 in the example device 900 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 920 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00138] Further, in various example embodiments, the example device 900 may also include at least one other circuitry, element, and interface, for example at least one I/O interface, at least one antenna element, and the like.

[00139] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 900, including the at least one processor 910 and the at least one memory 920, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00140] It is understood that the structure of the device on the side of the UE 110 is not limited to the above example device 900.

[00141] FIG. 10 shows a block diagram illustrating an example device 1000 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a network device such as the CU CP 215 of the BS 210 as the first BS in the above examples.

[00142] As shown in the FIG. 10, the example device 1000 may include at least one processor 1010 and at least one memory 1020 that may store instructions 1030. The instructions 1030, when executed by the at least one processor 1010, may cause the device 1000 at least to perform the example method 400 described above.

[00143] In various example embodiments, the at least one processor 1010 in the example device 1000 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 1010 may also include at least one other circuitry or element not shown in the FIG. 10.

[00144] In various example embodiments, the at least one memory 1020 in the example device 1000 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 1020 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00145] Further, in various example embodiments, the example device 1000 may also include at least one other circuitry, element, and interface, for example at least one VO interface, at least one antenna element, and the like.

[00146] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 1000, including the at least one processor 1010 and the at least one memory 1020, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00147] It is understood that the structure of the device on the side of the CU CP 215 is not limited to the above example device 1000.

[00148] FIG. 11 shows a block diagram illustrating an example device 1100 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a network device such as the CU CP 255 of the BS 250 as the first BS in the above examples.

[00149] As shown in the FIG. 11, the example device 1100 may include at least one processor 1110 and at least one memory 1120 that may store instructions 1130. The instructions 1130, when executed by the at least one processor 1110, may cause the device 1100 at least to perform the example method 500 described above.

[00150] In various example embodiments, the at least one processor 1110 in the example device 1100 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 1110 may also include at least one other circuitry or element not shown in the FIG. 11.

[00151] In various example embodiments, the at least one memory 1120 in the example device 1100 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 1120 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00152] Further, in various example embodiments, the example device 1100 may also include at least one other circuitry, element, and interface, for example at least one I/O interface, at least one antenna element, and the like.

[00153] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 1100, including the at least one processor 1110 and the at least one memory 1120, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00154] It is understood that the structure of the device on the side of the CU CP 255 is not limited to the above example device 1100.

[00155] FIG. 12 shows a block diagram illustrating an example device 1200 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a network device such as the CU CP 235 of the BS 230 as the first BS in the above examples.

[00156] As shown in the FIG. 12, the example device 1200 may include at least one processor 1210 and at least one memory 1220 that may store instructions 1230. The instructions 1230, when executed by the at least one processor 1210, may cause the device 1200 at least to perform the example method 600 described above.

[00157] In various example embodiments, the at least one processor 1210 in the example device 1200 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 1210 may also include at least one other circuitry or element not shown in the FIG. 12.

[00158] In various example embodiments, the at least one memory 1220 in the example device 1200 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 1220 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00159] Further, in various example embodiments, the example device 1200 may also include at least one other circuitry, element, and interface, for example at least one VO interface, at least one antenna element, and the like.

[00160] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 1200, including the at least one processor 1210 and the at least one memory 1220, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00161] It is understood that the structure of the device on the side of the CU CP 235 is not limited to the above example device 1200.

[00162] FIG. 13 shows a block diagram illustrating an example device 1300 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a network device such as the DU 212 of the BS 210 as the first BS in the above examples.

[00163] As shown in the FIG. 13, the example device 1300 may include at least one processor 1310 and at least one memory 1320 that may store instructions 1330. The instructions 1330, when executed by the at least one processor 1310, may cause the device 1300 at least to perform the example method 700 described above.

[00164] In various example embodiments, the at least one processor 1310 in the example device 1300 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 1310 may also include at least one other circuitry or element not shown in the FIG. 13.

[00165] In various example embodiments, the at least one memory 1320 in the example device 1300 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 1320 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00166] Further, in various example embodiments, the example device 1300 may also include at least one other circuitry, element, and interface, for example at least one VO interface, at least one antenna element, and the like.

[00167] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 1300, including the at least one processor 1310 and the at least one memory 1320, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00168] It is understood that the structure of the device on the side of the DU 212 is not limited to the above example device 1300.

[00169] FIG. 14 shows a block diagram illustrating an example device 1400 for multicast reception according to the example embodiments of the present disclosure. The device, for example, may be at least part of an apparatus for a network device such as the DU 252 of the BS 250 as the first BS in the above examples.

[00170] As shown in the FIG. 14, the example device 1400 may include at least one processor 1410 and at least one memory 1420 that may store instructions 1430. The instructions 1430, when executed by the at least one processor 1410, may cause the device 1400 at least to perform the example method 800 described above.

[00171] In various example embodiments, the at least one processor 1410 in the example device 1400 may include, but not limited to, at least one hardware processor, including at least one microprocessor such as a central processing unit (CPU), a portion of at least one hardware processor, and any other suitable dedicated processor such as those developed based on for example Field Programmable Gate Array (FPGA) and Application Specific Integrated Circuit (ASIC). Further, the at least one processor 1410 may also include at least one other circuitry or element not shown in the FIG. 14.

[00172] In various example embodiments, the at least one memory 1420 in the example device 1400 may include at least one storage medium in various forms, such as a transitory memory and/or a non-transitory memory. The transitory memory may include, but not limited to, for example, a random-access memory (RAM), a cache, and so on. The non- transitory memory may include, but not limited to, for example, a read only memory (ROM), a hard disk, a flash memory, and so on. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). Further, the at least memory 1420 may include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00173] Further, in various example embodiments, the example device 1400 may also include at least one other circuitry, element, and interface, for example at least one VO interface, at least one antenna element, and the like.

[00174] In various example embodiments, the circuitries, parts, elements, and interfaces in the example device 1400, including the at least one processor 1410 and the at least one memory 1420, may be coupled together via any suitable connections including, but not limited to, buses, crossbars, wiring and/or wireless lines, in any suitable ways, for example electrically, magnetically, optically, electromagnetically, and the like.

[00175] It is understood that the structure of the device on the side of the DU 252 is not limited to the above example device 1400.

[00176] FIG. 15 shows a block diagram illustrating an example apparatus 1500 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a terminal device such as the UE 110 in the above examples.

[00177] As shown in the FIG. 15, the example apparatus 1500 may comprise: means 1510 for receiving from a first cell, a configuration allowing the apparatus to receive a multicast service in RRC inactive state; means 1520 for of receiving from the first cell, a configuration for receiving the multicast service in the RRC inactive state; means 1530 for selecting to camp in the first cell and entering into the RRC inactive state; means 1540 for determining, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first MCCH; and means 1550 for based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, staying in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[00178] In some embodiments, the apparatus 1500 may comprise means for determining implicitly that the first cell operates the multicast service without the first MCCH in case at least one of the following is satisfied: detecting that the first cell operates without a SIB24, detecting that the first cell operates with a SIB24 without a configuration for the first MCCH, or detecting that the first cell operates with the first MCCH without a configuration for the multicast service. [00179] In some embodiments, the first cell is in a RAN, the multicast service is one of a plurality of multicast services in the RAN, and the apparatus 1500 may comprise means for determining whether the first cell or the RAN operates the multicast service without a MCCH or the plurality of multicast services without a MCCH.

[00180] In some embodiments, the apparatus 1500 may comprise means for receiving from the first cell, a group paging message indicating the apparatus to stay in the RRC inactive state to receive the multicast service; and means for based on the received group paging message, staying in the RRC inactive state to receive the multicast service.

[00181] In some embodiments, the apparatus 1500 may comprise means for upon performing a cell reselection to a second cell different from the first cell in the RRC inactive state, determining whether the second cell operates the multicast service without a second MCCH; and means for based on determining that the second cell operates the multicast service without the second MCCH, deciding to connect to the second cell, or based on determining that the second cell operates the multicast service with the second MCCH, deciding to stay in the RRC inactive state. [00182] In some embodiments, the apparatus 1500 may comprise means for determining that the second cell operates the multicast service without the second MCCH based on the determination that the first cell operates the multicast service without the first MCCH.

[00183] In some embodiments, the apparatus 1500 may comprise means for determining that the second cell operates the multicast service with the second MCCH. [00184] In some embodiments, the apparatus 1500 may comprise means for receiving from the first cell, information whether the second cell operates the multicast service with the second MCCH or without the second MCCH.

[00185] In some embodiments, the apparatus 1500 may comprise means for receiving from the first cell, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH.

[00186] In some embodiments, the apparatus 1500 may comprise means for receiving the information or the list of identifiers of cells with the information via a RRC release with suspend message or via the first MCCH.

[00187] In some embodiments, the apparatus 1500 may comprise means for connecting to the second cell without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell operates the multicast service without the second MCCH, and to stop monitoring RNTI is not indicated for one or more multicast services that the apparatus is configured to receive in the RRC inactive state.

[00188] In some example embodiments, examples of means in the example apparatus 1500 may include circuitries. For example, an example of means 1510 may include a circuitry configured to perform the operation 310 of the example method 300, an example of means 1520 may include a circuitry configured to perform the operation 320 of the example method 300, an example of means 1530 may include a circuitry configured to perform the operation 330 of the example method 300, an example of means 1540 may include a circuitry configured to perform the operation 340 of the example method 300, and an example of means 1550 may include a circuitry configured to perform the operation 350 of the example method 300.

[00189] The example apparatus 1500 may further include means comprising circuitry configured to perform the example method 300. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

[00190] FIG. 16 shows a block diagram illustrating an example apparatus 1600 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the CU CP 215 of the BS 210 as the first BS in the above examples.

[00191] As shown in the FIG. 16, the example apparatus 1600 may comprise: means 1610 for performing at least one of the following: transmitting to a DU of the first BS, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00192] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first base station, cells belonging to another DU of the first base station, or cells belonging to another base station.

[00193] In some example embodiments, examples of means in the example apparatus 1600 may include circuitries. For example, an example of means 1610 may include a circuitry configured to perform the operation 410 of the example method 400.

[00194] The example apparatus 1600 may further include means comprising circuitry configured to perform the example method 400. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

[00195] FIG. 17 shows a block diagram illustrating an example apparatus 1700 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the CU CP 255 of the BS 250 as the first BS in the above examples.

[00196] As shown in the FIG. 17, the example apparatus 1700 may comprise: means 1710 for receiving from a first DU of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means 1720 for performing at least one of the following: transmitting to one or more DUs of the first BS other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00197] In some example embodiments, examples of means in the example apparatus 1700 may include circuitries. For example, an example of means 1710 may include a circuitry configured to perform the operation 510 of the example method 500, and an example of means 1720 may include a circuitry configured to perform the operation 520 of the example method 500.

[00198] The example apparatus 1700 may further include means comprising circuitry configured to perform the example method 500. In some example embodiments, examples of means may also include software modules and any other suitable function entities. [00199] FIG. 18 shows a block diagram illustrating an example apparatus 1800 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the CU CP 235 of the BS 230 as the first BS in the above examples.

[00200] As shown in the FIG. 18, the example apparatus 1800 may comprise: means 1810 for receiving from a CU CP of a second BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means 1820 for transmitting to one or more DUs of the first BS, the list of identifiers of cells with the information.

[00201] In some example embodiments, examples of means in the example apparatus 1800 may include circuitries. For example, an example of means 1810 may include a circuitry configured to perform the operation 610 of the example method 600, and an example of means 1820 may include a circuitry configured to perform the operation 620 of the example method 600.

[00202] The example apparatus 1800 may further include means comprising circuitry configured to perform the example method 600. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

[00203] FIG. 19 shows a block diagram illustrating an example apparatus 1900 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the DU 212 of the BS 210 as the first BS in the above examples.

[00204] As shown in the FIG. 19, the example apparatus 1900 may comprise: means 1910 for receiving from a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and means 1920 for broadcasting the list of identifiers of cells with the information towards terminal devices served by the DU of the first BS.

[00205] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first BS, cells belonging to another DU of the first BS, or cells belonging to another BS.

[00206] In some example embodiments, examples of means in the example apparatus 1900 may include circuitries. For example, an example of means 1910 may include a circuitry configured to perform the operation 710 of the example method 700, and an example of means 1920 may include a circuitry configured to perform the operation 720 of the example method 700.

[00207] The example apparatus 1900 may further include means comprising circuitry configured to perform the example method 700. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

[00208] FIG. 20 shows a block diagram illustrating an example apparatus 2000 for multicast reception according to the example embodiments of the present disclosure. The apparatus, for example, may be at least part of a network device such as the DU 252 of the BS 250 as the first BS in the above examples.

[00209] As shown in the FIG. 20, the example apparatus 2000 may comprise: means 2010 for transmitting to a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH.

[00210] In some example embodiments, examples of means in the example apparatus 2000 may include circuitries. For example, an example of means 2010 may include a circuitry configured to perform the operation 810 of the example method 800.

[00211] The example apparatus 2000 may further include means comprising circuitry configured to perform the example method 800. In some example embodiments, examples of means may also include software modules and any other suitable function entities.

[00212] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a terminal device such as the UE 110 in the above examples, may cause the apparatus at least to: receive from a first cell, a configuration allowing the apparatus to receive a multicast service in RRC inactive state; receive from the first cell, a configuration for receiving the multicast service in the RRC inactive state; select to camp in the first cell and entering into the RRC inactive state; determine, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, stay in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

[00213] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: determine implicitly that the first cell operates the multicast service without the first MCCH in case at least one of the following is satisfied: detecting that the first cell operates without a SIB24, detecting that the first cell operates with a SIB24 without a configuration for the first MCCH, or detecting that the first cell operates with the first MCCH without a configuration for the multicast service.

[00214] In some embodiments, the first cell is in a RAN, the multicast service is one of a plurality of multicast services in the RAN, and the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: determine whether the first cell or the RAN operates the multicast service without a MCCH or the plurality of multicast services without a MCCH.

[00215] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: receive from the first cell, a group paging message indicating the apparatus to stay in the RRC inactive state to receive the multicast service; and based on the received group paging message, stay in the RRC inactive state to receive the multicast service.

[00216] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: upon performing a cell reselection to a second cell different from the first cell in the RRC inactive state, determine whether the second cell operates the multicast service without a second MCCH; and based on determining that the second cell operates the multicast service without the second MCCH, decide to connect to the second cell, or based on determining that the second cell operates the multicast service with the second MCCH, decide to stay in the RRC inactive state.

[00217] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: determine that the second cell operates the multicast service without the second MCCH based on the determination that the first cell operates the multicast service without the first MCCH.

[00218] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: determine that the second cell operates the multicast service with the second MCCH.

[00219] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: receive from the first cell, information whether the second cell operates the multicast service with the second MCCH or without the second MCCH.

[00220] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: receive from the first cell, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH. [00221] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: receive the information or the list of identifiers of cells with the information via a RRC release with suspend message or via the first MCCH.

[00222] In some embodiments, the computer readable medium may include instructions that, when executed by the apparatus, may cause the apparatus to: connect to the second cell without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell operates the multicast service without the second MCCH, and to stop monitoring RNTI is not indicated for one or more multicast services that the apparatus is configured to receive in the RRC inactive state.

[00223] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a network device such as the CU CP 215 of the BS 210 as the first BS in the above examples, may cause the apparatus at least to: perform at least one of the following: transmitting to a DU of the first BS, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00224] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first base station, cells belonging to another DU of the first base station, or cells belonging to another base station.

[00225] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a network device such as the CU CP 255 of the BS 250 as the first BS in the above examples, may cause the apparatus at least to: receive from a first DU of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and perform at least one of the following: transmitting to one or more DUs of the first BS other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second BS, the list of identifiers of cells with the information.

[00226] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a network device such as the CU CP 235 of the BS 230 as the first BS in the above examples, may cause the apparatus at least to: receive from a CU CP of a second BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and transmit to one or more DUs of the first BS, the list of identifiers of cells with the information.

[00227] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a network device such as the DU 212 of the BS 210 as the first BS in the above examples, may cause the apparatus at least to: receive from a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and broadcast the list of identifiers of cells with the information towards terminal devices served by the DU of the first BS.

[00228] In some embodiments, the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first BS, cells belonging to another DU of the first BS, or cells belonging to another BS.

[00229] The example embodiments of the present disclosure also provide a computer readable medium comprising program instructions that, when executed by an apparatus for a network device such as the DU 252 of the BS 250 as the first BS in the above examples, may cause the apparatus at least to: transmit to a CU CP of the first BS, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH. As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[00230] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehiclemounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), USB dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node). In the above description, the terms “terminal device”, “communication device”, “terminal”, “user equipment” and “UE” may be used interchangeably.

[00231] The term “circuitry” throughout this disclosure may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); (b) combinations of hardware circuits and software, such as (as applicable) (i) a combination of analog 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 a mobile phone or server, to perform various functions); 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. This definition of circuitry applies to one or all uses of this term in this disclosure, including in any claims. As a further example, as used in this disclosure, 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 and if applicable to the claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[00232] Another example embodiment may relate to computer program codes or instructions which may cause an apparatus to perform at least respective methods described above. Another example embodiment may be related to a computer readable medium having such computer program codes or instructions stored thereon. In some embodiments, such a computer readable medium may include at least one storage medium in various forms such as a volatile memory and/or a non-volatile memory. The volatile memory may include, but not limited to, for example, a RAM, a cache, and so on. The non-volatile memory may include, but not limited to, a ROM, a hard disk, a flash memory, and so on. The non-volatile memory may also include, but are not limited to, an electric, a magnetic, an optical, an electromagnetic, an infrared, or a semiconductor system, apparatus, or device or any combination of the above.

[00233] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. [00234] Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.

[00235] As used herein, the term "determine/determining" (and grammatical variants thereof) can include, not least: calculating, computing, processing, deriving, measuring, investigating, looking up (for example, looking up in a table, a database or another data structure), ascertaining and the like. Also, "determining" can include receiving (for example, receiving information), accessing (for example, accessing data in a memory), obtaining and the like. Also, "determine/determining" can include resolving, selecting, choosing, establishing, and the like. [00236] While some embodiments have been described, these embodiments have been presented by way of example, and are not intended to limit the scope of the disclosure. Indeed, the apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. At least one of these blocks may be implemented in a variety of different ways. The order of these blocks may also be changed. Any suitable combination of the elements and actions of the some embodiments described above can be combined to provide further embodiments. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.

[00237] Abbreviations used in the description and/or in the figures are defined as follows:

BS base station

CN core network

CP control plane

CU centralized unit

DU distributed unit F1AP Fl application protocol gNB next Generation Node B

ID identifier

MBS multicast and broadcast system MCCH multicast control channel

OAM operation administration and maintenance

PLMN public land mobile network

RAN radio access network

RNA RAN notification area RNTI radio network temporary identifier

RRC radio resource control

SIB24 system information block 24

TMGI temporary mobile group identity

UE user equipment XnAP Xn application protocol

Claims

WHAT IS CLAIMED IS:

1. An apparatus for a terminal device, comprising: at least one processor ; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receive from the first cell, a configuration for receiving the multicast service in the RRC inactive state; select to camp in the first cell and enter into the RRC inactive state; determine, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, stay in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

2. The apparatus of claim 1, wherein the apparatus is configured to: determine implicitly that the first cell operates the multicast service without the first MCCH in case at least one of the following is satisfied: detecting that the first cell operates without a system information block 24, SIB24, detecting that the first cell operates with a SIB24 without a configuration for the first MCCH, or detecting that the first cell operates with the first MCCH without a configuration for the multicast service.

3. The apparatus of claim 1, wherein the first cell is in a radio access network, the multicast service is one of a plurality of multicast services in the radio access network, and the apparatus is configured to: determine whether the first cell or the radio access network operates the multicast service without a MCCH or the plurality of multicast services without a MCCH.

4. The apparatus of any of claims 1 to 3, wherein the apparatus is configured to: receive from the first cell, a group paging message indicating the apparatus to stay in the RRC inactive state to receive the multicast service; and based on the received group paging message, stay in the RRC inactive state to receive the multicast service.

5. The apparatus of any of claims 1 to 4, wherein the apparatus is configured to: upon performing a cell reselection to a second cell different from the first cell in the RRC inactive state, determine whether the second cell operates the multicast service without a second MCCH; and based on determining that the second cell operates the multicast service without the second MCCH, decide to connect to the second cell, or based on determining that the second cell operates the multicast service with the second MCCH decide to stay in the RRC inactive state.

6. The apparatus of claim 5, wherein the apparatus is configured to: determine that the second cell operates the multicast service without the second MCCH based on the determination that the first cell operates the multicast service without the first MCCH.

7. The apparatus of claim 5, wherein the apparatus is configured to: determine that the second cell operates the multicast service with the second MCCH.

8. The apparatus of claim 5, wherein the apparatus is configured to: receive from the first cell, information whether the second cell operates the multicast service with the second MCCH or without the second MCCH.

9. The apparatus of claim 5, wherein the apparatus is configured to: receive from the first cell, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH.

10. The apparatus of claim 8 or 9, wherein the apparatus is configured to: receive the information or the list of identifiers of cells with the information via a RRC release with suspend message or via the first MCCH.

11. The apparatus of any of claims 8 to 10, wherein the apparatus is configured to: connect to the second cell without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell operates the multicast service without the second MCCH, and to stop monitoring radio network temporary identifier, RNTI is not indicated for one or more multicast services that the apparatus is configured to receive in the RRC inactive state.

12. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: perform at least one of the following: transmitting to a distributed unit, DU, of the first base station, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

13. An apparatus of claim 12, wherein the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first base station, cells belonging to another DU of the first base station, or cells belonging to another base station.

14. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a first distributed unit, DU, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and perform at least one of the following: transmitting to one or more DUs of the first base station other than the first DU, the list of identifiers of cells with the information; or transmitting to a CU CP of a second base station, the list of identifiers of cells with the information.

15. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus functioning as a centralized unit, CU, control plane, CP, of a first base station at least to: receive from a CU CP of a second base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and transmit to one or more DUs of the first base station, the list of identifiers of cells with the information.

16. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: receive from a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH; and broadcast the list of identifiers of cells with the information towards terminal devices served by the DU of the first base station.

17. An apparatus of claim 16, wherein the information whether the cells operate with a MCCH or without a MCCH concerns at least one of the following: cells belonging to the DU of the first base station, cells belonging to another DU of the first base station, or cells belonging to another base station.

18. An apparatus for a network device, comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus functioning as a distributed unit, DU, of a first base station at least to: transmit to a centralized unit, CU, control plane, CP, of the first base station, a list of identifiers of cells with information whether the cells operate with a MCCH or without a MCCH.

19. A method performed by an apparatus for a terminal device, comprising: receiving from a first cell, a configuration allowing the apparatus to receive a multicast service in radio resource control, RRC, inactive state; receiving from the first cell, a configuration for receiving the multicast service in the RRC inactive state; selecting to camp in the first cell and entering into the RRC inactive state; determining, implicitly based on available information on the first cell, whether the first cell operates the multicast service without a first multicast control channel, MCCH; and based on the configurations, the available information on the first cell and determining that the first cell operates the multicast service without the first MCCH, staying in the RRC inactive state in the first cell to receive the multicast service in the RRC inactive state.

20. The method of claim 19, comprising: determining implicitly that the first cell operates the multicast service without the first MCCH in case at least one of the following is satisfied: detecting that the first cell operates without a system information block 24, SIB24, detecting that the first cell operates with a SIB24 without a configuration for the first MCCH, or detecting that the first cell operates with the first MCCH without a configuration for the multicast service.

21. The method of claim 19, wherein the first cell is in a radio access network, the multicast service is one of a plurality of multicast services in the radio access network, and the method comprises: determining whether the first cell or the radio access network operates the multicast service without a MCCH or the plurality of multicast services without a MCCH.

22. The method of any of claims 19 to 21, comprising: receiving from the first cell, a group paging message indicating the apparatus to stay in the RRC inactive state to receive the multicast service; and based on the received group paging message, staying in the RRC inactive state to receive the multicast service.

23. The method of any of claims 19 to 22, comprising: upon performing a cell reselection to a second cell different from the first cell in the RRC inactive state, determining whether the second cell operates the multicast service without a second MCCH; and based on determining that the second cell operates the multicast service without the second MCCH, deciding to connect to the second cell, or based on determining that the second cell operates the multicast service with the second MCCH, deciding to stay in the RRC inactive state.

24. The method of claim 23, comprising: determining that the second cell operates the multicast service without the second MCCH based on the determination that the first cell operates the multicast service without the first MCCH.

25. The method of claim 23, comprising: determining that the second cell operates the multicast service with the second MCCH.

26. The method of claim 23, comprising: receiving from the first cell, information whether the second cell operates the multicast service with the second MCCH or without the second MCCH.

27. The method of claim 23, comprising: receiving from the first cell, a list of identifiers of cells, with information whether the cells operate with a MCCH or without a MCCH.

28. The method of claim 26 or 27, comprising: receiving the information or the list of identifiers of cells with the information via a RRC release with suspend message or via the first MCCH.

29. The method of any of claims 26 to 28, comprising: connecting to the second cell without reading a SIB24 or expecting reception of the SIB24 or the second MCCH, in case the following are satisfied: the second cell operates the multicast service without the second MCCH, and to stop monitoring radio network temporary identifier, RNTI is not indicated for one or more multicast services that the apparatus is configured to receive in the RRC inactive state.

30. An apparatus for a terminal device, comprising means for performing the method of any of claims 19 to 29.

31. A computer readable medium comprising program instructions that, when executed by an apparatus for a terminal device, cause the apparatus to at least perform the method of any of claims 19 to 29.