Network device and client device

Abstract

According to an example embodiment, a network device is configured to: generate an indicator based on at least one of an active state or a data inactive state of a multicast session; and sending an indicator to the client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and cease monitoring the data of the multicast session when the client device is in an inactive state.

Description

Technical Field

[0001] The present invention relates generally to the field of wireless communications and more particularly to network devices, client devices, and related methods and computer programs. Background Art

[0002] In fifth generation (5G) cellular networks, client devices, such as user equipment (UE), may transition to an inactive state to save power when, for example, there is no traffic to the client device. This may be referred to as a radio resource control (RRC) inactive (RRC_INACTIVE) state. However, various problems may arise due to the client device being in an inactive state. Summary of the invention

[0003] The scope of protection sought by various example embodiments is set forth by the independent claims. Example embodiments and features described in this specification that do not belong to the scope of the independent claims, if any, should be construed as examples that aid in understanding the various example embodiments.

[0004] An example embodiment of a network device includes at least one processor and at least one memory, wherein the at least one memory stores instructions. The instructions, when executed by the at least one processor, cause the network device to: generate an indicator based on at least one of an activation state or a data inactivity state of a multicast session; and send the indicator to a client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state.

[0005] An example embodiment of a network device includes components for performing the following items: generating an indicator based on at least one of an activation state or a data inactivity state of a multicast session; and sending the indicator to a client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state.

[0006] In an example embodiment, alternatively or additionally to the above example embodiments, the data inactivity status is based on whether the network device has received data for the multicast session within a predetermined time duration.

[0007] In an exemplary embodiment, alternatively or additionally to the above exemplary embodiments, the network device is further enabled to send an indicator in a radio resource control RRC release message or in a multicast and broadcast control channel MCCH.

[0008] An example embodiment of a client device includes at least one processor and at least one memory, wherein the at least one memory stores instructions. When the instructions are executed by the at least one processor, the client device: obtains an indication from a network device, wherein the indication indicates to the client device whether the client device should wait for a paging message for a multicast session and stop monitoring data of the multicast session when the client device is in an inactive state; and based on the obtained indication, if the indication indicates that the client device should not wait for a paging message, monitors data of the multicast session when the client device is in an inactive state.

[0009] An example embodiment of a client device includes a component for performing the following: obtaining an indication from a network device, wherein the indication indicates to the client device whether the client device should wait for a paging message for a multicast session and stop monitoring data for the multicast session when the client device is in an inactive state; and based on the obtained indication, if the indication indicates that the client device should not wait for a paging message, monitoring data for the multicast session when the client device is in an inactive state.

[0010] In an exemplary embodiment, alternatively or additionally to the above exemplary embodiment, the client device also waits for a paging message for a multicast session and stops monitoring data of the multicast session when the client device is in an inactive state if an indication indicates that the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session.

[0011] In an example embodiment, alternatively or additionally to the above example embodiments, obtaining the indication includes receiving an indicator, wherein the indicator explicitly indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data for the multicast session when the client device is in an inactive state from the network device or detects a lack of an indicator from the network device.

[0012] In an example embodiment, alternatively or additionally to the above example embodiments, the multicast session comprises an active multicast session.

[0013] In an exemplary embodiment, alternatively or additionally to the above exemplary embodiments, the client device is further enabled to obtain an indicator in a radio resource control RRC release message or in a multicast and broadcast control channel MCCH.

[0014] In an example embodiment, alternatively or additionally to the above example embodiment, the client device is further caused to maintain a radio bearer for the multicast session as active and monitor the data of the multicast session when the client device is in an inactive state in response to an indication indicating that the client device should not wait for a paging message for the multicast session and monitor the data of the multicast session.

[0015] In an example embodiment, alternatively or additionally to the above example embodiments, monitoring the data of the multicast session includes: monitoring a group radio network temporary identifier G-RNTI of the multicast session.

[0016] In an example embodiment, alternatively or additionally to the above example embodiment, the client device is further configured to receive a paging message according to the indication in response to obtaining an indication from a network device controlling the first cell and selecting a second cell controlled by a second network device for camping in an inactive state when the client device camps in the second cell.

[0017] In an example embodiment, alternatively or additionally to the above example embodiments, the client device is also caused to switch from an inactive state to a connected state in response to at least one criterion being met, in response to an indication indicating that the client device should not wait for a paging message for a multicast session and monitor data for the multicast session.

[0018] In an example embodiment, alternatively or additionally to the above example embodiments, at least one criterion includes at least: the client device sends from a connected state to an inactive state in a first cell controlled by the network device, the client device switches to a second cell to reside in the inactive state; and the client device does not find a multicast and broadcast control channel MCCH in the second cell.

[0019] An example embodiment of the method includes: generating, by a network device, an indication based on at least one of an activation state or a data inactivity state of a multicast session; and sending, by the network device, the indication to a client device, wherein the indication indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state.

[0020] An example embodiment of a method includes:

[0021] A client device obtains an indication from a network device, wherein the indication indicates to the client device whether the client device should wait for a paging message for a multicast session and stop monitoring data of the multicast session when the client device is in an inactive state; and based on the obtained indication, if the indication indicates that the client device should not wait for the paging message, the client device monitors the data of the multicast session when the client device is in an inactive state.

[0022] An exemplary embodiment of a computer program product comprises a program code configured to perform a method according to any one of the above exemplary embodiments when the computer program product is executed on a computer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are included to provide a further understanding of example embodiments and constitute a part of this specification, illustrate example embodiments and together with the description help explain the principles of example embodiments. In the drawings:

[0024] Figure 1 An example embodiment of a network device is shown that illustrates the subject matter described herein;

[0025] Figure 2 An example embodiment of the subject matter described herein showing a client device is shown;

[0026] Figure 3 A schematic diagram showing a signaling diagram according to an example;

[0027] Figure 4 A schematic diagram showing a signaling diagram according to an example;

[0028] Figure 5 A schematic diagram showing a signaling diagram according to an example;

[0029] Figure 6 A schematic diagram showing a signaling diagram according to an example;

[0030] Figure 7 A schematic diagram showing a signaling diagram according to an example;

[0031] Figure 8 A schematic diagram showing a signaling diagram according to an example;

[0032] Fig. 9 A schematic diagram showing a signaling diagram according to an example embodiment;

[0033] Fig.10 A flowchart showing a method according to an example embodiment; and

[0034] Fig.11 A flow chart of a method according to an example embodiment is shown.

[0035] In the drawings, like reference numerals are used to denote like components. DETAILED DESCRIPTION

[0036] Reference will now be made in detail to example embodiments, examples of which are illustrated in the accompanying drawings. The specific embodiments provided below in conjunction with the accompanying drawings are intended as a description of this example and are not intended to represent the only form in which the present disclosure may be constructed or utilized. The description sets forth the functions of the example and the order of steps for constructing and operating the example. However, the same or equivalent functions and sequences may be implemented by different example embodiments.

[0037] Figure 1 is a block diagram of a network device 100 configured in accordance with an example embodiment.

[0038] The network device 100 may include one or more processors 101 and one or more memories 102 including instructions. The network device 100 may also include at least one antenna port, as well as other elements such as input / output modules, transceivers and / or communication interfaces ( Figure 1 not shown).

[0039] According to an example embodiment, the instructions, when executed by at least one processor, cause the network device 100 to: generate an indicator based on at least one of an activation state or a data inactivity state of a multicast session; and send the indicator to a client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state.

[0040] An indicator may also be referred to as an indication, a paging indicator, a paging indication, or the like.

[0041] For example, in some example embodiments, network device 100 may provide a "wait for paging" indicator to a user equipment (UE) in a radio resource control (RRC) release message, wherein the indicator indicates to the UE whether the UE should wait for paging for a particular multicast session or for all multicast sessions, or not wait for paging for a particular multicast session or for all multicast sessions. Network device 100 may send an RRC release message, for example, because there is temporarily no data in a multicast service for transmission to the UE. Additionally or alternatively, network device 100 may send the indicator to a client device in other messages and / or situations (such as those disclosed herein).

[0042] A multicast service may be provided through a multicast session. In this document, multicast session and multicast service may be used interchangeably.

[0043] According to an example embodiment, the data inactivity state is based on whether the network device has received data for the multicast session within a predetermined duration. In other words, if the network device has not received any data for the multicast within the predetermined duration, the data inactivity state can be set to inactive. In this case, the indicator can instruct the UE to wait for paging. If there is upcoming data, the indicator can instruct the client device to continue monitoring the data instead of waiting.

[0044] According to an example embodiment, the activity state of the multicast session may be, for example, inactive / deactivated or active. For the inactive / deactivated state, the indicator may indicate that the UE is waiting for paging. For the active state, the indicator may indicate that the client device continues to monitor data from the multicast session (rather than waiting for paging) even though the client device is sent to the inactive mode. Even for an active multicast session, the client device may temporarily have no data to transmit.

[0045] Although network device 100 may be depicted as including only one processor 101, network device 100 may include more processors. In an example embodiment, memory 102 is capable of storing instructions, such as an operating system and / or various applications.

[0046] In addition, the processor 101 may be capable of executing stored instructions. In an example embodiment, the processor 101 may be embodied as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and one or more single-core processors. For example, the processor 101 may be embodied as one or more of a variety of processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuit system with or without an accompanying DSP, or various other processing devices, including integrated circuits, such as, for example, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), microcontroller units (MCUs), hardware accelerators, special-purpose computer chips, etc. In an example embodiment, the processor 101 may be configured to perform hard-coded functions. In an example embodiment, the processor 101 is embodied as an executor of software instructions, wherein the instructions may specifically configure the processor 101 to perform the algorithms and / or operations described herein when the instructions are executed.

[0047] The memory 102 may be implemented as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, the memory 102 may be embodied as a semiconductor memory (such as a mask ROM, a PROM (programmable ROM), an EPROM (erasable PROM), a flash ROM, a RAM (random access memory), etc.).

[0048] When the network device 100 is configured to implement a certain function, a certain component and / or certain components of the network device 100 (such as at least one processor 101 and / or memory 102) may be configured to implement the function. In addition, when the at least one processor 101 is configured to implement a certain function, the function may be implemented using, for example, a program code included in the memory 102. For example, if the network device 100 is configured to perform an operation, the at least one memory 102 and the computer program code may be configured to enable the network device 100 to perform the operation together with the at least one processor 101.

[0049] The network device 100 may include, for example, a base station (BS), a next-generation Node B (gNB), or any such device that provides an air interface for client devices to connect to a wireless network via wireless transmission.

[0050] Certain terms used herein may follow the naming scheme of the current form of 4G or 5G technology. However, this terminology should not be considered limiting, and the terminology may change over time. Therefore, the following discussion about any example embodiment may also apply to other technologies.

[0051] Figure 2 is a block diagram of a client device 200 configured in accordance with an example embodiment.

[0052] The client device 200 may include one or more processors 201 and one or more memories 202 including instructions. The client device 200 may also include at least one antenna port, as well as other elements such as an input / output module, a transceiver, a display, and / or a communication interface ( Figure 2 not shown).

[0053] According to an example embodiment, the instructions, when executed by at least one processor, cause the client device 200 to: obtain an indication from the network device 100, wherein the indication indicates to the client device 200 whether the client device 200 should wait for a paging message for a multicast session and stop monitoring data of the multicast session when the client device 200 is in an inactive state; and based on the obtained indication, if the indication indicates that the client device should not wait for a paging message, monitor the data of the multicast session when the client device 200 is in an inactive state.

[0054] The client device 200 may include, for example, a UE.

[0055] Herein, paging may also be referred to as a paging message or the like.

[0056] According to an example embodiment, the client device 200 is also caused to wait for a paging message for a multicast session and stop monitoring data of the multicast session when the client device 200 is in an inactive state based on the obtained indication, if the indication indicates that the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session.

[0057] The client device 200 may include configuration related to the multicast session, and the paging may indicate activation of the multicast session for the client device 200 or indicate the arrival of data for the multicast session.

[0058] For example, if the indication indicates that the client device 200 needs to wait for paging for a multicast session, the client device 200 may suspend a multicast radio bearer (MRB) associated with the multicast session.

[0059] If the indication indicates that the client device 200 does not need to wait for paging, the client device 200 may not suspend the MRB (ie, keep the MRB active) and may receive a group radio network temporary identifier (G-RNTI) for the multicast session data.

[0060] If the client device 200 obtains another indication indicating that the client device 200 needs to wait for paging for the multicast session, the client device 200 may ignore the previously obtained indication.

[0061] According to an example embodiment, obtaining the indication includes receiving an indicator from the network device. In this case, the indicator can explicitly indicate to the client device 200 whether the client device 200 should wait for a paging message for the multicast session and stop monitoring the data of the multicast session when the client device 200 is in an inactive state.

[0062] According to another example embodiment, obtaining the indication includes detecting the absence of an indicator from the network device. In a first embodiment, in the case where the client device does not receive such an indicator from the network device, the client device can interpret it as a trigger to wait for a paging message for the multicast session when the client device 200 is in an inactive state and stop monitoring the data of the multicast session. In a second embodiment, in the case where the client device does not receive such an indicator from the network device, the client device can interpret it as a trigger to not wait for a paging message for the multicast session when the client device 200 is in an inactive state and keep monitoring the data of the multicast session. The behavior of the client device in such a case (i.e., whether to perform the first or second embodiment) can be preconfigured.

[0063] In the following, most examples are written such that obtaining an indication comprises receiving an indicator from a network device. However, the embodiments are also applicable to the case where obtaining an indication is performed by detecting the absence of an indicator (ie, by not receiving the indicator).

[0064] For example, in some example embodiments, when the UE receives a "wait for paging" indicator in the RRC release message, the UE may not expect to receive the G-RNTI for the service and suspend the MRB for the multicast session until the UE receives a group paging for the corresponding service indicating activation of the multicast session or arrival of data for the multicast session. For example, even if the session state received by the UE is active, the UE may perform such an operation regardless of the value of the session state it receives in the RRC release message.

[0065] For example, in some example embodiments, when the UE receives the "do not wait for paging" indicator, the UE may assume that the session is active and may not suspend the MRB for the multicast session and continue to monitor the G-RNTI for the multicast session. As described above, in some embodiments, the absence of the "wait for paging" indicator may serve as an indicator that the UE should not wait for paging for the multicast session.

[0066] In some example embodiments, the indicator is additionally or alternatively sent to the UE in a multicast and broadcast control channel (MCCH). When the UE checks the MCCH for a particular service and detects a "wait for page" indicator, the UE may not wait for the G-RNTI, suspend the MRB for the service, and wait for paging for the multicast session, even though the session is active.

[0067] Although the client device 200 may be depicted as including only one processor 201, the client device 200 may include more processors. In an example embodiment, the memory 202 can store instructions, such as an operating system and / or various applications.

[0068] In addition, the processor 201 may be capable of executing stored instructions. In an example embodiment, the processor 201 may be embodied as a multi-core processor, a single-core processor, or a combination of one or more multi-core processors and one or more single-core processors. For example, the processor 201 may be embodied as one or more of a variety of processing devices, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing circuit system with or without an accompanying DSP, or various other processing devices, including integrated circuits, such as, for example, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), microcontroller units (MCUs), hardware accelerators, special-purpose computer chips, etc. In an example embodiment, the processor 201 may be configured to perform hard-coded functions. In an example embodiment, the processor 201 is embodied as an executor of software instructions, wherein the instructions may specifically configure the processor 201 to perform the algorithms and / or operations described herein when the instructions are executed.

[0069] The memory 202 may be embodied as one or more volatile memory devices, one or more non-volatile memory devices, and / or a combination of one or more volatile memory devices and non-volatile memory devices. For example, the memory 202 may be embodied as a semiconductor memory (such as a mask ROM, a PROM (programmable ROM), an EPROM (erasable PROM), a flash ROM, a RAM (random access memory), etc.).

[0070] When the client device 200 is configured to implement certain functions, a certain component and / or certain components of the client device 200 (such as at least one processor 201 and / or memory 202) may be configured to implement the function. In addition, when the at least one processor 201 is configured to implement certain functions, the function may be implemented using, for example, a program code included in the memory 202. For example, if the client device 200 is configured to perform an operation, the at least one memory 202 and the computer program code may be configured to, together with the at least one processor 201, enable the client device 200 to perform the operation.

[0071] At least some example embodiments disclosed herein may, for example, enable the client device 200 to stop monitoring the G-RNTI, suspend the MRB, and save power during periods of time when there is no data transmission for the multicast service while the 5G core maintains the session state active for the multicast service. At least some example embodiments may also enable the client device 200 to obtain information to enable the necessary connection to the network.

[0072] Figure 3 A schematic diagram of a signaling diagram according to an example is shown.

[0073] In Rel-17, the gNB may send the UE 200 to the RRC_INACTIVE state, for example, for power saving, if the following conditions are met:

[0074] 1) All multicast sessions that UE 200 has joined have an inactive / deactivated state; or

[0075] 2) The multicast session that UE 200 has joined has an active state, but there is temporarily no activity in the user plane (ie, no incoming data).

[0076] The Rel-17 UE 200 does not know which of the above cases (1) and (2) causes the UE to be sent to the RRC_INACTIVE state, because the "session activation state" is unknown to the Rel-17 UE 200. For both cases, the UE 200 starts waiting for paging for the multicast session after being sent to the RRC_INACTIVE state. For case (1), the gNB pages once the session is activated, and for case (2), the gNB pages once some data arrives for the multicast session, so that the UE 200 returns to the RRC_CONNECTED state for data reception.

[0077] However, Rel-18 introduces multicast reception in the RRC_INACTIVE state, on top of the Rel-17 mechanism for reception in the RRC_CONNECTED state. Thus, a Rel-18 UE 200 may be sent to the RRC_INACTIVE state and may be expected to receive multicast transmissions, i.e., the UE 200 does not wait for paging.

[0078] The RRC release message may be used when sending the UE 200 to the RRC_INACTIVE state, and the RRC release message may include the point-to-multipoint (PTM) configuration required for the UE 200 to receive multicast. In addition, the periodic MCCH may indicate the PTM configuration that the UE 200 needs to use in the RRC_INACTIVE state multicast reception. If the RRC_INACTIVE UE 200 does not have the PTM configuration for the "active" multicast session, it reconnects and returns to the RRC_CONNECTED state for multicast reception (because the audience size may not be very large and the UE is served in RRC_CONNECTED).

[0079] For Rel-18 UE 200, to understand such "session activation state", "session state" can be indicated in both RRC release and MCCH. In this way, UE 200 in RRC_INACTIVE state can distinguish between active and inactive multicast sessions, and UE 200 can use such operation to determine whether to return to RRC_CONNECTED state or stay in RRC_INACTIVE state.

[0080] In addition, in the RRC release message, the UE 200 may be instructed whether to continue the MRBs that the UE is using in the RRC_CONNECTED state and in the RRC_INACTIVE state, so as to have service continuity without interruption when transitioning from the RRC_CONNECTED state to the RRC_INACTIVE state. The "session state" may be utilized for such a purpose that if the MRBs that the UE 200 is using in the RRC_CONNECTED state are used for "inactive" multicast sessions, the UE 200 suspends these MRBs; if the MRBs that the UE 200 is using in the RRC_CONNECTED state are used for "active" multicast sessions, the UE 200 does not suspend these MRBs.

[0081] However, such a framework may present problematic scenarios. For example, UE 200 may be in RRC_CONNECTED state 301 receiving multicast service A. If the gNB decides 302 to release UE 200 to RRC_INACTIVE state for an "active" multicast session, due to case (2) above, and sends an RRC release message 303 from cell 1 400_1 to UE 200, UE 200 does not suspend the MRB. The UE expects 304 to receive data in RRC_INACTIVE state using the MRB used in RRC_CONNECTED state, and attempts to decode 305 the multicast service, even though there is no data for the time being, and UE 200 does not stop monitoring the G-RNTI for the service. Such a situation may cause unnecessary power consumption at UE 200. In short, UE 200 cannot understand the reason why it was sent to RRC_INACTIVE state.

[0082] Furthermore, UE 200 does not expect 306 group paging for multicast service A. Therefore, when data for service A arrives 307 and gNB1 performs group paging 308, UE 200 may miss the group paging and stay in RRC_INACTIVE state 309.

[0083] Figure 4 A schematic diagram of a signaling diagram according to an example is shown.

[0084] UE 200 may enter RRC_INACTIVE state without having any "session state" provided by gNB1 in RRC release message 402. For example, cell 1 of gNB1 400_1 may be in congested state 401, and gNB1 may want to keep the RRC release size to a minimum and expect UE 200 to know the session state via MCCH. In this case, UE 200 may end up initially camping in a different cell where SIB20 / MCCH is not provided. For example, in Figure 4 In the example of , UE 200 suspends 404 all MRBs and performs cell selection 405. For example, the new cell may be a Rel-17gNB or a Rel-18gNB, whose multicast service 406 has a smaller audience size, such as Figure 4 Cell 2 of gNB 2500_2 in the example. The “session state” for UE 200 may be unknown. In such a case, the behavior of UE 200 is undefined and UE 200 may not find SIB20 and may not reconnect because the session state is unknown 407.

[0085] from Figure 3 and Figure 4 As can be seen from the exemplary scenarios of FIG. 1 , some solutions for RRC_INACTIVE state multicast may cause problems when UE 200 is sent to the RRC_INACTIVE state for different purposes. Therefore, a method is needed to improve the behavior of the UE after being sent to the RRC_INACTIVE state. For example, after being sent to the RRC_INACTIVE state, UE 200 may not be able to determine whether it should stay in the RRC_INACTIVE state and wait for paging for a multicast session, whether it should stay in the RRC_INACTIVE state and wait for data reception, and / or whether it should enter the RRC_CONNECTED state for data reception.

[0086] Figure 5 A schematic diagram of a signaling diagram according to an example embodiment is shown.

[0087] exist Figure 5 In the exemplary embodiment of FIG. 3 , in operation 301 , the UE is in the RRC_CONNECTED state and receives the multicast service A.

[0088] In operation 302, since service A has no data arriving temporarily and the UE does not receive other services, gNB1 decides to release the UE to the RRC_INACTIVE state. gNB1 may correspond to network device 100.

[0089] According to an example embodiment, the network device is further caused to send the indicator in a Radio Resource Control (RRC) release message or in a Multicast and Broadcast Control Channel (MCCH).

[0090] In other example embodiments, network device 100 may send the indication, for example, in some other message or in a separate message.

[0091] According to an example embodiment, the client device 200 is also caused to obtain an indication in a Radio Resource Control (RRC) release message or in a Multicast and Broadcast Control Channel (MCCH).

[0092] According to an example embodiment, obtaining the indication includes receiving an indicator ( Figure 5 501), wherein the indicator explicitly indicates to the client device 200 whether the client device 200 should wait for a paging message for a multicast session and stop monitoring data for the multicast session or detecting a lack of an indicator from a network device when the client device 200 is inactive.

[0093] In other example embodiments, client device 200 may receive the indicator, for example, in some other message or in a separate message.

[0094] According to an example embodiment, the multicast session comprises an active multicast session.

[0095] For example, in Figure 5 In the example embodiment, gNB1 cell 1 400_1 sends and UE 200 receives an indicator in an RRC release message 501. The RRC release message 501 may also indicate that the multicast session is active.

[0096] According to an example embodiment, the indicator indicates to the client device 200 whether the client device 200 should wait for paging for the multicast session.

[0097] The indicator may, for example, indicate to the client device 200 whether the client device 200 should wait for paging of a particular multicast session. In another example, the indicator may indicate to the client device 200 whether the client device 200 should wait for paging of all multicast sessions.

[0098] exist Figure 5 In the example embodiment, gNB1 sends an RRC release message 501, which includes an indication that service A is active and an indication of "waiting for paging" because UE 200 will be paged when data for multicast service A arrives.

[0099] According to an example embodiment, the client device 200 is further caused to suspend a radio bearer for the multicast session in response to an indication indicating that the client device 200 should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device 200 is inactive.

[0100] For example, in Figure 5 In the example embodiment of , in operation 502, UE 200 expects to receive group paging for multicast service A in RRC_INACTIVE state, and suspends its use of MRB for multicast service A in RRC_CONNECTED state because RRC release is due to temporary lack of data activity. UE 200 does not monitor the G-RNTI for multicast service A. Therefore, UE 200 does not consume power unnecessarily, as shown in step 503.

[0101] In operation 504, due to the measurement, the UE 200 reselects the cell 2 of the gNB1 400_2 for camping. In operation 505, the UE 200 camps in the cell 2 400_2.

[0102] In operation 506, UE 200 may wait for paging for multicast service A even though the 400_2MCCH of cell 2 may indicate that the multicast session is active and may not indicate "wait for paging".

[0103] In operation 307, data for multicast service A arrives.

[0104] Cell 1 of gNB1 400_1 sends group paging 507 to cell 2 of gNB1 400_2 via the Xn interface. Group paging 507 indicates the arrival of data for multicast service A.

[0105] Cell 2 of gNB1 400_2 sends group paging 308 to UE 200.

[0106] In operation 508, UE 200 receives group paging 308 indicating arrival of data for multicast service A, and returns to RRC_CONNECTED state in cell 2 400_2 for data reception 509. Alternatively, using enhanced group paging, UE 200 may also stay in RRC_INACTIVE state and receive data for a multicast session.

[0107] Figure 6 A schematic diagram of a signaling diagram according to an example embodiment is shown.

[0108] exist Figure 6 In the exemplary embodiment of FIG. 3 , in operation 301 , UE 200 is in an RRC_CONNECTED state receiving multicast service A.

[0109] In operation 401, gNB 1 decides to release the UE to RRC_INACTIVE state, e.g. due to congestion.

[0110] According to one embodiment, the at least one memory 202 and the computer program code are further configured to, with the at least one processor 201, cause the client device 200 to maintain a radio bearer active for a multicast session when the client device 200 is in an inactive state in response to an indicator indicating that the client device 200 should not wait for paging or an indicator was not received from the network device 100.

[0111] According to an example embodiment, the client device 200 is also caused to maintain a radio bearer for the multicast session active and monitor data of the multicast session when the client device 200 is in an inactive state in response to an indication indicating that the client device 200 should not wait for a paging message for the multicast session and monitor data of the multicast session.

[0112] According to an example embodiment, monitoring the multicast session for data includes monitoring a Group Radio Network Temporary Identifier (G-RNTI) of the multicast session.

[0113] For example, in Figure 6 In the example embodiment of , cell 1 of gNB 1 400_1 may send an RRC release message 601 without PTM configuration or session state to UE 200. Optionally, gNB 1 may also provide an indicator for "not waiting for paging" to UE 200, because UE 200 intends to receive services in RRC_INACTIVE state. Alternatively, the absence of an explicit "waiting for paging" may be used as a "not waiting for paging" indicator.

[0114] According to one embodiment, the client device 200 is also configured to receive a paging message according to the indication in response to obtaining an indication from a network device controlling the first cell and selecting a second cell controlled by a second network device for camping in an inactive state when the client device is camping in the second cell.

[0115] In some example embodiments, the network device and the second network device may be the same. In other embodiments, they may be different devices.

[0116] For example, in some embodiments, if UE 200 is provided with a "wait for paging" indicator in the RRC release message, UE 200 may wait for paging and not attempt to decode any data, such as the G-RNTI, even if UE 200 reselects a new cell for camping and the new cell does not indicate "wait for paging".

[0117] In some embodiments, the client device 200 may also be configured to respond to obtaining an indication from a network device controlling a first cell and selecting a second cell controlled by a second network device for camping in an inactive state, without waiting to receive a paging message according to the indication when the client device is camping in the second cell.

[0118] For example, in some example embodiments, if UE 200 is provided with a "not waiting for paging" indicator in the RRC release message, UE 200 may still wait for paging and not attempt to decode any data, such as a G-RNTI, in the camped cell where the MCCH indicates "waiting for paging".

[0119] For example, in Figure 6 In the example embodiment, in operation 602, UE 200 does not suspend MRB. In operation 603, UE 200 performs cell selection for initial camping and finds that cell 2 of gNB2 500_2 is the best cell.

[0120] In operation 406, gNB2 does not provide multicast services to UEs in RRC_INACTIVE state. This may be due to, for example, that gNB2 is a Rel-17 gNB or Rel-18 gNB without SIB20 / MCCH.

[0121] In operation 604, UE 200 is unable to find SIB20 in cell 2 of gNB2 500_2. Based on an explicit "do not wait for paging" indicator or based on the absence of a "wait for paging" indicator, UE 200 does not wait for paging and returns to the RRC_CONNECTED state to receive multicast transmission 605 in the RRC_CONNECTED state by initiating a connection recovery or connection establishment procedure.

[0122] Figure 7 A schematic diagram of a signaling diagram according to an example embodiment is shown.

[0123] exist Figure 7 In the example embodiment, in operation 701, UE 200 is in RRC_INACTIVE state and receives multicast service A from cell 2 of gNB1400_2.

[0124] In operation 702, due to the measurement, UE 200 reselects cell 1 of gNB1 400_1 for camping.

[0125] In operation 703, due to the temporary absence of data, cell 1 of gNB1 400_1 releases some other UEs to the RRC_INACTIVE state.

[0126] According to an example embodiment, the at least one memory 102 and the computer program code are further configured to, with the at least one processor 101 , cause the network device 100 to send the indicator in the MCCH.

[0127] According to an example embodiment, the at least one memory 202 and the computer program code are further configured to, with the at least one processor 201 , cause the client device 200 to receive the indicator in the MCCH.

[0128] For example, in Figure 7 In the example embodiment of , MCCH 704 indicates for multicast service A that service A is active and that UE 200 should wait for paging even though session A is active.

[0129] In operation 705, the UE 200 waits for paging and suspends the MRB for the multicast service A while the session is active.

[0130] In operation 706, data arrival for multicast service A occurs, and cell 1 paging 707 of gNB1400_1 supports UEs of multicast service A involving UE 200.

[0131] In operation 708, after receiving the paging, the UE 200 enters the RRC_CONNECTED state for data reception 709. Alternatively, using enhanced group paging, the UE 200 may also stay in the RRC_INACTIVE state and receive data.

[0132] Figure 8 A schematic diagram of a signaling diagram according to an example embodiment is shown.

[0133] exist Figure 8 In an example embodiment, the network device 100 includes a split gNB, which includes a distributed unit (DU) 801, a centralized unit (CU) control plane (CP) 802 and a CP user plane (UP) 803.

[0134] In operation 804 , multicast session A is active, but no data has been delivered for a period of time. CU UP 803 may send an E1 Application Protocol (E1AP) inactivity notification 805 for service A to CUCP 802 .

[0135] In some example embodiments, CU CP 802 may send an RRC release message 806 including a "wait for page" indicator to UE 200. Any disclosure herein regarding indicators in an RRC release message may also apply to this example embodiment.

[0136] In some example embodiments, CU CP 802 may send an F1 Application Protocol (F1AP) multicast bearer context modification (CU to DU RRC information) including a "wait for paging" indicator to DU 801 in operation 807. DU 801 may send an MCCH broadcast including a "wait for paging" indicator to UE 200 in operation 808. Any disclosure herein regarding indicators in the MCCH may also apply to this example embodiment.

[0137] Fig. 9 A schematic diagram of a signaling diagram according to an example embodiment is shown.

[0138] exist Fig. 9 In the exemplary embodiment of FIG. 3 , in operation 301 , UE 200 is in an RRC_CONNECTED state for receiving multicast service A.

[0139] In operation 401, gNB1 decides to release UE 200 to RRC_INACTIVE state, for example due to congestion.

[0140] Cell 1 of gNB1 400_1 sends an RRC release message 402 to UE 200 without PTM configuration or session status.

[0141] In operation 404, the UE 200 suspends all MRBs.

[0142] In operation 405, UE 200 performs initial cell selection and finds that the best cell is cell 2 of gNB2 500_2.

[0143] In operation 406, cell 2 of gNB2 500_2 does not provide multicast services to UEs in RRC_INACTIVE state. This may be due to, for example, that gNB2 is a Rel-17 gNB or a Rel-18 gNB without SIB20 / MCCH.

[0144] According to an example embodiment, the client device 200 is further caused to switch from the inactive state to the connected state in response to at least one criterion being met in response to an indication indicating that the client device should not wait for a paging message for the multicast session and monitor data for the multicast session.

[0145] For example, in Fig. 9 In the example embodiment of , UE 200 does not receive an explicit indicator in RRC release message 402. This may serve as an indication that UE 200 should not wait for a paging message for the multicast session.

[0146] According to an example embodiment, the at least one criterion includes at least: the client device 200 is sent from a connected state to an inactive state in a first cell controlled by a network device, the client device 200 switches to a second cell to camp in the inactive state; and the client device 200 does not find multicast and MCCH in the second cell.

[0147] The first cell may include, for example, a cell from which the client device 200 receives an RRC release message, such as Fig. 9 Cell 1 of gNB1 400_1 in the example embodiment.

[0148] In other embodiments, the at least one criterion may further include other criteria and / or include different criteria.

[0149] In some example embodiments, the client device 200 may be configured to switch to the RRC_CONNECTED state in response to not receiving an indicator in a session activation state and / or RRC release message, the client device 200 is camped on a cell that is not the cell that sent the client device 200 to the RRC_INACTIVE state, and the camped cell does not transmit SIB20 / MCCH.

[0150] For example, in Fig. 9 In the example embodiment of , in operation 901, UE 200 cannot find SIB20 after switching to cell 2 of gNB2 500_2. When the following conditions are met, UE 200 returns to the RRC_CONNECTED state by initiating a connection recovery or establishment procedure, and the connection is recovered or established 902:

[0151] 1. UE 200 does not receive the session state for the multicast session it joined in the RRC Release message 402,

[0152] 2. UE 200 has selected another cell to initially camp on than the cell that sent UE 200 to the RRC_INACTIVE state, and

[0153] 3. UE 200 cannot find SIB20 and / or MCCH in the cell where it initially camps.

[0154] Fig.10 A flowchart representation of a method according to an example embodiment is shown.

[0155] According to one embodiment, method 1000 includes generating 1001 an indicator by a network device based on at least one of an activation state or a data inactivity state of a multicast session, and sending 1002 an indicator by the network device to a client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state.

[0156] The method 1000 may be performed by, for example, the network device 100 .

[0157] Fig.11 A flowchart representation of a method according to an example embodiment is shown.

[0158] According to one embodiment, method 1100 includes: obtaining 1101 an indication by a client device from a network device, wherein the indication indicates to the client device whether the client device should wait for a paging message for a multicast session and stop monitoring data of the multicast session when the client device is in an inactive state, and based on the obtained indication, if the indication indicates that the client device should not wait for the paging message, monitoring 1102 the data of the multicast session by the client device when the client device is in an inactive state.

[0159] The method 1100 may be performed by, for example, the client device 200 .

[0160] An apparatus may include means for performing any aspect of the method(s) described herein. According to an example embodiment, the means include at least one processor and a memory, and the memory includes program code, the at least one processor and the program code being configured to cause the execution of any aspect of the method when executed by the at least one processor.

[0161] The functions described herein may be performed, at least in part, by one or more computer program product components (such as software components). According to an example embodiment, the network device 100 and / or the client device 200 includes a processor configured by a program code that, when executed, performs an example embodiment of the operations and functions described. Additionally or alternatively, the functions described herein may be performed, at least in part, by one or more hardware logic components. For example, but not limited to, example types of hardware logic components that may be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and graphics processing units (GPUs).

[0162] Any range or device value given herein may be expanded or changed without losing the effect sought. In addition, unless explicitly not permitted, any exemplary embodiment may be combined with another exemplary embodiment.

[0163] Although the subject matter has been described in language specific to structural features and / or acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as examples of implementing the claims, and other equivalent features and acts are intended to fall within the scope of the claims.

[0164] It should be understood that the benefits and advantages described above may relate to one example embodiment or may relate to several example embodiments. The example embodiments are not limited to those that solve any or all of the problems described or have any or all of the benefits and advantages described. It should also be understood that reference to "an" item may refer to one or more of those items.

[0165] The steps of the methods described herein may be performed in any suitable order, or simultaneously where appropriate. In addition, individual blocks may be deleted from any method without departing from the spirit and scope of the subject matter described herein. Aspects of any of the example embodiments described above may be combined with aspects of other example embodiments described to form further example embodiments without losing the effects sought.

[0166] The term "comprising" is used herein to mean including the identified methods, blocks or elements, but these blocks or elements do not include an exclusive list and the method or apparatus may contain additional blocks or elements.

[0167] It should be understood that the above description is given by way of example only, and various modifications may be made by those skilled in the art. The above description, examples and data provide a complete description of the structure and use of the example embodiments. Although various example embodiments have been described above with a certain degree of particularity or with reference to one or more separate example embodiments, those skilled in the art may make many modifications to the disclosed example embodiments without departing from the spirit or scope of this specification.

Claims

1. A network device (100), comprising: at least one processor (101); as well as at least one memory (102), the at least one memory storing instructions that, when executed by the at least one processor, cause the network device (100): generating the indicator based on at least one of: an activation state of the multicast session, or a data inactivity state; as well as The indicator is sent to the client device (200), wherein the indicator indicates to the client device (200) whether the client device (200) should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device (200) is in an inactive state. 2 . The network device of claim 1 , wherein the data inactivity state is based on whether the network device has received data for the multicast session within a predetermined time duration.

3. The network device (100) according to claim 1 or claim 2, wherein the network device (100) is also enabled to send the indicator in a radio resource control RRC release message (501, 601, 806) or in a multicast and broadcast control channel MCCH (704, 808).

4. A client device (200), comprising: at least one processor (201); as well as At least one memory (202), the at least one memory storing instructions, which when executed by the at least one processor (201), cause a client device (200) of a multicast session to: Obtaining an indication from a network device (100), wherein the indication indicates to a client device (200): whether the client device (200) should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device (200) is in an inactive state; as well as Based on the obtained indication, perform one of the following: monitoring the data of the multicast session while the client device (200) is in the inactive state if the indication indicates that the client device should not wait for the paging message; If the indication indicates that the client device should wait for the paging message for the multicast session and stop monitoring the data of the multicast session, then when the client device (200) is in the inactive state, it waits for the paging message for the multicast session and stops monitoring the data of the multicast session.

5. The client device (200) of claim 4, wherein obtaining the indication comprises receiving an indicator, wherein the indicator explicitly indicates to the client device (200) whether the client device (200) should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device (200) is in the inactive state from the network device or detects the absence of the indicator from the network device.

6. The client device of any one of claims 4 to 5, wherein the multicast session comprises an active multicast session.

7. The client device (200) according to any one of claims 4 to 6, wherein the client device (200) is further configured to obtain the indication in a radio resource control RRC release message (501, 601, 806) or in a multicast and broadcast control channel MCCH (704, 808).

8. The client device (200) according to any one of claims 4 to 7, wherein the client device (200) is further configured to: in response to the indication that the client device (200) should not wait for the paging message for the multicast session and monitor the data of the multicast session, keep the radio bearer for the multicast session active and monitor the data of the multicast session when the client device (200) is in the inactive state.

9. The client device (200) of claim 8, wherein monitoring the data of the multicast session comprises: A Group Radio Network Temporary Identifier (G-RNTI) of the multicast session is monitored.

10. The client device (200) according to any one of claims 4 to 9, wherein the client device (200) is further configured to: in response to obtaining the indication from the network device controlling the first cell (400_1) and selecting a second cell controlled by a second network device (500_2) for camping in the inactive state, receive the paging message according to the indication when the client device (200) camps in the second cell (500_2).

11. A client device (200) according to any one of claims 4 to 10, wherein the client device (200) is further configured to: in response to the indication that the client device should not wait for the paging message for the multicast session and monitor the data of the multicast session, switch from the inactive state to the connected state in response to at least one criterion being met.

12. The client device (200) according to claim 11, wherein the at least one criterion comprises at least: The client device (200) transmits from the connected state to the inactive state in a first cell controlled by the network device, The client device (200) switches to a second cell to reside in the inactive state (500_2); and The client device (200) does not find a multicast and broadcast control channel MCCH in the second cell (500_2).

13. The client device according to any one of claims 4 to 12, wherein the client device is further caused to: select a second cell to camp on; and switch to a connected state in the second cell in response to not receiving SIB20 / MCCH in the second cell.

14. The client device of claim 13, wherein the client device is further caused to: receive an RRC release message from the first cell, the RRC release message not including the indication and / or the multicast session activation status.

15. A method (1000) comprising: The indicator is generated by the network device based on at least one of: an activation state or a data inactivity state of the multicast session; as well as The indicator is sent (1002) by the network device to a client device, wherein the indicator indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is inactive.

16. A method (1100), comprising: Obtaining (1101) an indication from a network device by a client device, wherein the indication indicates to the client device whether the client device should wait for a paging message for the multicast session and stop monitoring data of the multicast session when the client device is in an inactive state; as well as Based on the obtained indication, perform one of the following: monitoring (1102), by the client device, the data of the multicast session while the client device is in the inactive state if the indication indicates that the client device should not wait for the paging message; If the indication indicates that the client device should wait for the paging message for the multicast session and stop monitoring the data of the multicast session, then when the client device (200) is in the inactive state, it waits for the paging message for the multicast session and stops monitoring the data of the multicast session.

17. A computer program product comprising a program code, the program code being configured to perform the method according to claim 15 or claim 16 when the computer program product is executed on a computer.

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