Optimized multicast and broadcast system data forwarding with separate GNB

Abstract

Embodiments of the present disclosure relate to a method, apparatus, apparatus, and computer readable storage medium for optimized multicast and broadcast system (MBS) data forwarding with separate gNodeB (gNB). A method includes receiving, from a second apparatus, a request for an Xn handover associated with a user equipment (UE); obtaining an Xn forwarding address associated with the Xn handover from the third device before the F1 UE context is established between the first device and the fourth device or before the fourth device triggers establishment of an F1-U forwarding tunnel for the Xn handover in the MBS session establishment or modification; and delivering the Xn forwarding address to at least one of: delivering to the fourth device before the fourth device triggers an F1-U forwarding tunnel establishment for Xn handover; or before the fourth device triggers an F1-U forwarding tunnel for the Xn handover and / or before the F1 UE context is established between the first device and the fourth device, delivering to the second device in an acknowledgement message for a request for the Xn handover.

Description

Technical Field

[0001] Various exemplary embodiments of this disclosure generally relate to the telecommunications field, and more specifically to methods, apparatus, devices, and computer-readable storage media for data forwarding using an optimized multicast and broadcast system (MBS) with a separate gNodeB (gNB). Background Technology

[0002] The 3rd Generation Partnership Project (3GPP) has completed a work item for supporting MBS in New Radio (NR). In this document, Point-to-Multipoint (PTM) transmission is envisioned to efficiently provide MBS service to multiple users using the same radio architecture as unicast transmission. UE reception of multicast service is enabled only in the Radio Resource Control (RRC) Connected (RRC_CONNECTED) state. Furthermore, broadcast reception in all RRC states has been specified.

[0003] The gNB can be separated into a centralized unit (CU) containing higher-level protocols and a distributed unit (DU) containing lower-level protocols. Furthermore, the CU itself can be separated into a control plane (CP) portion named CU-CP and a user plane (UP) portion named CU-UP.

[0004] It also adds data forwarding to MBS. It supports both monolithic gNBs and discrete gNBs. Data can be forwarded from the source gNB to the destination gNB through one or more Xn-U forwarding tunnels. Summary of the Invention

[0005] In a first aspect of this disclosure, a first apparatus is provided. The first apparatus includes: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus to at least: receive a request for Xn handover related to a user equipment (UE) from a second apparatus; obtain an Xn forwarding address related to the Xn handover from a third apparatus during MBS session establishment or modification, before an F1 UE context is established between the first apparatus and a fourth apparatus, or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for the Xn handover; and deliver the Xn forwarding address to at least one of the following: before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for the Xn handover, to the fourth apparatus; or before the fourth apparatus triggers the F1-U forwarding tunnel for the Xn handover and / or before an F1 UE context is established between the first apparatus and the fourth apparatus, in an acknowledgment message for the Xn handover request, to the second apparatus.

[0006] In a second aspect of this disclosure, a second apparatus is provided. The second apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus to at least: transmit a request for an Xn handover associated with a UE to a first apparatus; and receive an Xn forwarding address associated with the Xn handover from the first apparatus in an acknowledgment message for the request for the Xn handover before the fourth apparatus triggers an F1-U forwarding tunnel and / or before an F1 UE context is established between the first apparatus and the fourth apparatus.

[0007] In a third aspect of this disclosure, a third apparatus is provided. The third apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second apparatus to transmit an Xn forwarding address for Xn handover to the first apparatus at least: during MBS session establishment or modification, before an F1 UE context is established between the first apparatus and the fourth apparatus, or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for UE-related Xn handover.

[0008] In a fourth aspect of this disclosure, a fourth apparatus is provided. The fourth apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the fourth apparatus to at least: receive an Xn forwarding address for Xn handover from a first apparatus before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with the UE; and transmit, together with the Xn forwarding address, an F1-U DU address of the fourth apparatus for the establishment of the F1-U forwarding tunnel for Xn handover to the first apparatus.

[0009] In a fifth aspect of this disclosure, a method is provided. The method includes: receiving from a second device a request for an Xn handover related to a UE; obtaining an Xn forwarding address related to the Xn handover from a third device during MBS session establishment or modification, before an F1 UE context is established between a first device and a fourth device, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for the Xn handover; and delivering the Xn forwarding address to at least one of the following: before the fourth device triggers the establishment of the F1-U forwarding tunnel for the Xn handover, delivering it to the fourth device; or before the fourth device triggers the F1-U forwarding tunnel for the Xn handover and / or before the F1 UE context is established between the first device and the fourth device, delivering it to the second device in an acknowledgment message for the Xn handover request.

[0010] In a sixth aspect of this disclosure, a method is provided. The method includes: transmitting to a first device a request for an Xn handover associated with a UE; and receiving, in an acknowledgment message for the Xn handover request, an Xn forwarding address associated with the Xn handover from the first device before a fourth device triggers an F1-U forwarding tunnel and / or before an F1 UE context is established between the first and fourth devices.

[0011] In a seventh aspect of this disclosure, a method is provided. The method includes: during MBS session establishment or modification, before an F1 UE context is established between a first device and a fourth device, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for UE-related Xn handover, transmitting an Xn forwarding address for Xn handover to the first device.

[0012] In an eighth aspect of this disclosure, a method is provided. The method includes: receiving an Xn forwarding address for Xn handover from a first device before a fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with a UE; and transmitting, together with the Xn forwarding address, an F1-UDU address of the fourth device for the establishment of the F1-U forwarding tunnel for Xn handover to the first device.

[0013] In a ninth aspect of this disclosure, a first apparatus is provided. The first apparatus includes: components for receiving a request for an Xn handover related to a UE from a second apparatus; components for obtaining an Xn forwarding address related to the Xn handover from a third apparatus during MBS session establishment or modification, before an F1 UE context is established between the first apparatus and a fourth apparatus, or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for the Xn handover; and components for delivering the Xn forwarding address to at least one of the following: delivering it to the fourth apparatus before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for the Xn handover; or delivering it to the second apparatus in an acknowledgment message for the Xn handover request before the fourth apparatus triggers the F1-U forwarding tunnel for the Xn handover and / or before an F1 UE context is established between the first apparatus and the fourth apparatus.

[0014] In a tenth aspect of this disclosure, a second apparatus is provided. The second apparatus includes: components for transmitting a request for a UE-related Xn handover to a first apparatus; and components for receiving an Xn forwarding address related to the Xn handover from the first apparatus in an acknowledgment message for the Xn handover request before a fourth apparatus triggers an F1-U forwarding tunnel and / or before an F1 UE context is established between the first apparatus and the fourth apparatus.

[0015] In the eleventh aspect of this disclosure, a third apparatus is provided. The third apparatus includes components for transmitting an Xn forwarding address for Xn handover to the first apparatus during MBS session establishment or modification, before the F1 UE context is established between the first apparatus and the fourth apparatus, or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for UE-related Xn handover.

[0016] In a twelfth aspect of this disclosure, a fourth apparatus is provided. The fourth apparatus includes: a component for receiving an Xn forwarding address for Xn handover from a first apparatus before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with the UE; and a component for transmitting, together with the Xn forwarding address, an F1-U DU address of the fourth apparatus for the establishment of the F1-U forwarding tunnel for Xn handover to the first apparatus.

[0017] In a thirteenth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to perform at least the method according to the fifth aspect.

[0018] In a fourteenth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to perform at least the method according to a sixth aspect.

[0019] In a fifteenth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to perform at least the method according to a seventh aspect.

[0020] In a sixteenth aspect of this disclosure, a computer-readable medium is provided. The computer-readable medium includes instructions stored thereon for causing a device to perform at least the method according to an eighth aspect.

[0021] It should be understood that the summary portion is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0022] Some exemplary embodiments will now be described with reference to the accompanying drawings, in which: Figure 1 An example communication environment in which example embodiments of the present disclosure may be implemented is shown; Figure 2 A signaling diagram illustrating examples of processes according to some exemplary embodiments of the present disclosure is shown; Figure 3 A flowchart is shown illustrating a method implemented at a first device according to some example embodiments of the present disclosure; Figure 4 A flowchart illustrating a method implemented at a second device according to some example embodiments of the present disclosure is shown; Figure 5 A flowchart is shown illustrating a method implemented at a third device according to some example embodiments of the present disclosure; Figure 6 A flowchart is shown illustrating a method implemented at a fourth device according to some example embodiments of the present disclosure; Figure 7 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and Figure 8 A block diagram of an example computer-readable medium according to some example embodiments of the present disclosure is shown.

[0023] Throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. Detailed Implementation

[0024] The principles of this disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are described for illustrative purposes only and to help those skilled in the art to understand and implement this disclosure, without implying any limitation on the scope of this disclosure. The embodiments described herein can be implemented in various ways other than those described below.

[0025] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0026] References to "an embodiment," "embodiment," "example embodiment," etc., in this disclosure indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment includes that particular feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. In addition, when a particular feature, structure, or characteristic is described in conjunction with an example embodiment, it is to be noted that those skilled in the art will recognize, whether explicitly described or not, that such features, structures, or characteristics apply in conjunction with other embodiments.

[0027] It should be understood that although terms such as "first," "second," etc., preceding (multiple) nouns may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another, and they do not restrict the order of (multiple) nouns. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0028] As used herein, “at least one of the following: ” and “at least one of ” and similar wording, wherein a list of two or more elements combined with “and” or “or” means at least one of these elements, or any two or more of these elements, or at least all of these elements.

[0029] As used herein, unless explicitly stated otherwise, the execution step “in response to A” does not indicate that the step is executed immediately after “A” occurs, and may include one or more intermediate steps.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” “having,” “possessing,” “containing,” and / or “covering,” as used herein, specify the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0031] The term "circuit system" as used in this application may refer to one or more of the following: (a) Hardware circuit implementation only (such as implementation in analog and / or digital circuits only) and (b) A combination of hardware circuitry and software, such as (if applicable): (i) A combination of (multiple) analog and / or digital hardware circuits and software / firmware, and (ii) Any part of the (multiple) hardware processors (including (multiple) digital signal processors), software, and (multiple) memories, which work together to enable a device (such as a mobile phone or server) to perform various functions and (c) (Multiple) hardware circuits and / or (multiple) processors, such as (multiple) microprocessors or a portion thereof, which require software (e.g. firmware) to operate, but may not exist when the software is not required to operate.

[0032] The definition of "circuit system" applies to all uses of the term in this application, including any claim. As yet another example, as used in this application, the term "circuit system" also covers implementations of hardware circuitry or processors (or processors) or a portion thereof, including but not limited to hardware circuitry or processors and their accompanying software and / or firmware. The term "circuit system" also covers, for example (and if applicable to a particular claim element), baseband integrated circuits or processor integrated circuits for mobile devices or similar integrated circuits in servers, cellular network devices, or other computing or networking devices.

[0033] As used herein, the term "communication network" refers to a network that conforms to any suitable communication standard, such as New Radio (NR), Long Term Evolution (LTE), LTE-A Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, communication between terminal devices and network devices in a communication network can be performed according to any suitable generated communication protocol, including but not limited to first-generation (1G), second-generation (2G), 2.5G, 2.75G, third-generation (3G), fourth-generation (4G), 4.5G, fifth-generation (5G), sixth-generation (6G) communication protocols and / or any other currently known or future-developed protocols. Embodiments of this disclosure can be applied to various communication systems. Given the rapid development in communications, future types of communication technologies and systems will naturally exist, which can be used to implement this disclosure. The scope of this disclosure should not be limited to the aforementioned systems only.

[0034] As used herein, the term "network device" refers to a node in a communications network through which terminal devices access the network and receive services. Depending on the terminology and technology applied, a network device can refer to a base station (BS) or access point (AP), such as a Node B (NodeB or NB), an evolved Node B (eNodeB or eNB), an NR NB (also known as a gNB), a Remote Radio Unit (RRU), a Radio Header (RH), a Remote Radio Header End (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low-power node (such as a femtosecond or picosecond), a non-terrestrial network (NTN) or non-terrestrial network device (such as a satellite network device), a low Earth orbit (LEO) satellite and a geostationary Earth orbit (GEO) satellite, a spacecraft network device, etc. In some example embodiments, the Radio Access Network (RAN) split architecture includes a centralized unit (CU) and a distributed unit (DU) at the IAB donor node. An IAB node includes a mobile terminal (IAB-MT) portion that behaves like a UE toward the parent node, and a DU portion that behaves like a base station toward the next-hop IAB node.

[0035] The term "terminal device" refers to any end device with wireless communication capabilities. As an example and not a limitation, a terminal device can refer to communication equipment, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices can include, but are not limited to, mobile phones, cellular phones, smartphones, Voice over IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image acquisition terminal devices (such as digital cameras), gaming terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEE), laptop mounted devices (LME), USB dongles, smart devices, wireless client devices (CPE), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. Terminal equipment can also correspond to the mobile terminal (MT) portion of an IAB node (also known as a relay node). In the following description, the terms "terminal equipment," "communication equipment," "terminal," "user equipment," and "UE" are used interchangeably.

[0036] As used herein, the terms “resource,” “transmission resource,” “resource block,” “physical resource block” (PRB), “uplink resource,” or “downlink resource” can refer to any resource used to perform communication, such as communication between a terminal device and a network device, including time-domain resources, frequency-domain resources, spatial-domain resources, code-domain resources, or any other combination of time-domain, frequency-domain, spatial-domain, and / or code-domain resources capable of communication. In the following, unless explicitly stated otherwise, resources in both the frequency and time domains will be used as examples of transmission resources used to describe some exemplary embodiments of this disclosure. Note that the exemplary embodiments of this disclosure are equally applicable to other resources in other domains.

[0037] As described above, data forwarding is added to MBS. It supports both integrated and discrete gNBs. Data can be forwarded from the source gNB to the destination gNB through one or more Xn-U forwarding tunnels.

[0038] At the target gNB, if the target gNB is a split gNB, for each UE undergoing handover, a dedicated F1-U forwarding tunnel can be established between the target CU UP and the target DU to forward lost packets (if any) to the first UE via the target DU. If the MBS delivery at the source gNB is later than the MBS delivery at the target gNB, the first UE may lose packets. For example, if the source gNB is still transmitting packet sequence number (SN) 100 while the target gNB is already transmitting packet SN 110 during the first UE handover, then when the first UE arrives, it will be missing packets SN 101 to SN 109.

[0039] In the 3GPP solution, there is no one-to-one mapping between the Xn forwarding tunnel and the F1-U forwarding tunnel. This is because, instead, for a given first UE, the packets to be forwarded through the F1-U forwarding tunnel are determined by the target CU-UP using the first UE's "MRB progress information".

[0040] The first UE MRB progress information is the current SN used at the source gNB, which includes this current SN in its Xn handover request to the target gNB CU CP. For example, the first UE MRB progress information would correspond to SN=100. The target CU CP requests an F1-U forwarding tunnel from the target DU that includes the first UE MRB progress information (SN=100). Then, when the target DU triggers the establishment of the F1-U forwarding tunnel, it forwards the received first UE MRB progress information (SN=100) to the target CU UP via the target CU CP. Based on the received first UE MRB progress information (SN=100), the target CU UP can remember that the packet to be delivered to the first UE through this F1-U forwarding tunnel needs to start at SN 101.

[0041] Assuming that when the target CU receives the Xn handover request for the first UE, it is ahead of the source gNB and is currently transmitting packets for SN110, then if the target CU-UP still has packets for the first UE (i.e., packets from SN 101 to SN 109) to be transmitted through the F1-U forwarding tunnel in its buffer, the target CU-UP may decide not to allocate the Xn forwarding tunnel.

[0042] If an Xn forwarding tunnel has already been established for the incoming handover of the second UE, and the Xn forwarding tunnel is already able to provide the required packets (i.e., packets from SN 101 to SN 109) for the UE F1-U forwarding tunnel, then it may be decided not to allocate an Xn forwarding tunnel for the first UE.

[0043] Therefore, in the first case, the first UE will have an F1-U forwarding tunnel but not an Xn forwarding tunnel, or in the second case, the first UE's F1-U forwarding tunnel will deliver packets from the second UE's Xn forwarding tunnel, which is very unusual in 3GPP.

[0044] In summary, using the current MBS data forwarding scheme, when there is an Xn handover of the first UE, there is no need for a one-to-one mapping between the Xn forwarding tunnel and the F1-U forwarding tunnel of the first UE, because the packets to be forwarded on the F1-U forwarding tunnel for the first UE are determined based on the UE MRB information (SN of the last packet delivered to the first UE at the source gNB).

[0045] An alternative approach has been proposed to avoid the CU UP relying on UE MRB progress information to determine which packets to send via the F1-U forwarding tunnel. Instead, the target DU includes a new F1-U context reference in its F1 UE context establishment response, which the target DU will further use when establishing the F1-U forwarding tunnel. Subsequently, the target CU CP stores this F1-U context reference in its target CU CP UE context.

[0046] Then, the target DU triggers the establishment of an F1-U forwarding tunnel toward the target CU UP via the target CU CP, which includes the F1-U context reference. The target CU CP then requests an Xn forwarding address from the target CU UP. The target CU CP receives the Xn forwarding address from the target CU UP. The target CU CP then needs to identify, at step 8, which UE context has previously received the F1-U context reference. Once identified, the target CU CP can also store the received Xn forwarding address in the identified UE context. When the target CU CP sends an Xn handover request acknowledgment associated with the UE context back to the source gNB, it can therefore include the Xn forwarding tunnel address. The target CU UP can bind the Xn forwarding tunnel and the F1-U forwarding tunnel for the UE.

[0047] MBS data forwarding for split gNBs in 3GPP solutions may have the following main problems.

[0048] First, it delays the handover because the forwarding process depends on the UE MBR process information to be sent from the source gNB to the target gNB. The problem is that when the source gNB is a split gNB, this introduces additional operations for the source CU CP to obtain the UE MBR process information (i.e., the current packet SN delivered by the source CU UP), which can degrade handover performance.

[0049] Secondly, the 3GPP solution does not use a one-to-one mapping between the Xn forwarding tunnel of the first UE and the F1-U forwarding tunnel of the same first UE. This requires complex and novel processing in the target CU UP to remember which packets must be delivered on which F1-U forwarding tunnels, and whether these packets were already expected to be received from the Xn forwarding tunnel of the second UE. This is more complex logic than the simple one-to-one mapping / binding between the Xn forwarding tunnel and its F1-U forwarding tunnel of the first UE, where all packets received through the Xn forwarding tunnel are forwarded directly from the target CU UP to the target DU without any further logic or processing.

[0050] While the alternative proposed to avoid relying on UE MRB progress information addresses part of the problem in the 3GPP solution, it still has some other drawbacks. For example, it eliminates the delay caused by additional operations in the 3GPP solution, but sending the Xn handover request confirmation to the source gNB is still relatively late, and therefore it is not fully optimized.

[0051] Furthermore, it introduces complex parsing in the target CU CP. Therefore, the target CU CP, which receives the Xn forwarding address and F1-U context reference from the CU UP, needs to parse all its UE contexts to find a UE context with the same F1-U context reference received in the F1 UE context establishment response message. This is because the process of establishing the F1-U forwarding tunnel uses a non-UE association procedure, while the F1 UE context establishment response uses a UE association procedure; therefore, it is necessary to identify the correct UE context by parsing all UE contexts.

[0052] Figure 1 An example communication environment 100 in which example embodiments of the present disclosure may be implemented is shown. For example... Figure 1 As shown, the communication environment 100 includes a first device 110, a second device 120, a third device 130, and a fourth device 140. The first device 110 can communicate with the second device 120, the third device 130, and the fourth device 140, respectively.

[0053] The first device 110, the second device 120, the third device 130, and the fourth device 140 can each be a network device in the RAN, such as a gNB. In some example embodiments, the first device 110, the third device 130, and the fourth device 140 can be logically or physically implemented as discrete components of the RAN network device.

[0054] exist Figure 1In the example shown, the first device 110 can be referred to as gNB CU CP, the third device 130 can be referred to as gNB CU UP, and the fourth device 140 can be referred to as gNB DU. Specifically, the gNB CU CP can be connected to the gNB DU via an F1-C interface, while the gNB CU UP can be connected to the gNB DU via an F1-U interface. The second device 120 can be referred to as another gNB. The second device 120 can be connected to the first device 110 via an Xn interface.

[0055] Furthermore, the communication environment 100 may also include a terminal device 150 (e.g., a UE). In some scenarios, the terminal device 150 may be served by a second device 120. As the radio conditions between the second device 120 and the terminal device 150 change, a handover process for the terminal device 150 can be initiated, for example, a handover to the first device 110. In this case, the second device 120 may act as the source gNB of the terminal device 150 during the handover process. The first device 110, the third device 130, and the fourth device 140 may act as the target gNB CU CP, the target gNB CU UP, and the target gNB DU, respectively.

[0056] In some example embodiments, the link from the network device to the end device is referred to as a downlink (DL), and the link from the end device to the network device is referred to as an uplink (UL). In the DL, the network device is a transmitting (TX) device (or transmitter), and the end device is a receiving (RX) device (or receiver). In the UL, the end device is a TX device (or transmitter), and the network device is an RX device (or receiver).

[0057] Communication in communication environment 100 can be implemented according to any suitable communication protocol, including but not limited to cellular communication protocols such as first-generation (1G), second-generation (2G), third-generation (3G), fourth-generation (4G), fifth-generation (5G), and sixth-generation (6G), wireless local area network communication protocols such as IEEE 802.11, and / or any other currently known or future-developed protocols. Furthermore, communication can utilize any suitable wireless communication technology, including but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplex (FDD), Time Division Duplex (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM), Discrete Fourier Transform Extended OFDM (DFT-s-OFDM), and / or any other currently known or future-developed technologies.

[0058] According to some example embodiments of this disclosure, a solution for MBS data forwarding optimized using a split gNB is provided. In this solution, the source gNB transmits a request for a UE-related Xn handover to the target CU CP. During MBS session establishment or modification, before establishing an F1 UE context between the target CU CP and the target DU, or before the target DU triggers the establishment of an F1-U forwarding tunnel for Xn handover, the target CU CP obtains an Xn forwarding address related to the Xn handover from the target CU UP. Then, the target CU CP delivers the obtained Xn forwarding address to the target DU before the target DU triggers the establishment of an F1-U forwarding tunnel; and / or delivers the obtained Xn forwarding address to the source gNB before the target DU triggers the establishment of an F1-U forwarding tunnel for Xn handover, or before establishing an F1 UE context between the target CU CP and the target DU.

[0059] In this way, handover latency can be optimized, and simple logic can be established in the target CU-UP, with a one-to-one mapping between the UE's Xn forwarding tunnel and the F1-U forwarding tunnel established for the same UE. The handover latency can be optimized because the source gNB can trigger the handover to the UE upon receiving a handover request confirmation message containing the Xn forwarding address.

[0060] The exemplary embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0061] Now for reference Figure 2 This illustrates signaling diagram 200 of an example procedure based on normal handover according to some example embodiments of the present disclosure. For example... Figure 2 As shown, signaling diagram 200 relates to a first device 110, a second device 120, a third device 130, and a fourth device 140. For the purposes of discussion, reference will be made to... Figure 1 Discuss signaling diagram 200.

[0062] like Figure 2 As shown, if you want to initiate a communication with the UE (e.g., Figure 5 If the terminal device 150 in the first device 110 is associated with Xn handover, then the second device 120 can send an (205) Xn handover request message to the first device 110.

[0063] Then, the first device 110 can establish a multicast MBS context in the third device 130.

[0064] For example, if an MBS context for the multicast MBS session does not already exist, the first device 110 and the third device 130 perform a multicast MBS context establishment process; otherwise, they perform an MBS context modification process directed towards the third device 130.

[0065] As part of the multicast MBS context establishment or modification process, the first device 110 may request (210) the Xn forwarding address associated with the Xn handover from the third device 130, for example, via an E1 BC bearer context establishment / modification request message.

[0066] In some embodiments, before establishing an F1 UE context between the first device 110 and the fourth device 140, the first device 110 may request (210) an Xn forwarding address related to Xn handover from the third device 130. In some other embodiments, before the fourth device 140 triggers the establishment of an F1-U forwarding tunnel for Xn handover, the first device 110 may request (210) an Xn forwarding address related to Xn handover from the third device 130.

[0067] Upon receiving a request for an Xn forwarding address related to the Xn handover, the third device 130 can allocate the Xn forwarding address and send it back to the first device 110, for example, via an E1 BC bearer context modification response message. That is, the first device 110 can obtain the Xn forwarding address related to the Xn handover before establishing an F1 UE context between the first device 110 and the fourth device 140 and / or before the fourth device 140 triggers the establishment of an F1-U forwarding tunnel for the Xn handover.

[0068] Upon receiving the Xn forwarding address related to the Xn handover from the third device 130, the first device 110 may immediately deliver the obtained Xn forwarding address to the second device 120, for example, via an Xn handover request confirmation message. Before the fourth device 140 triggers the F1-U forwarding tunnel for the Xn handover and / or before establishing a UE context between the first device 110 and the fourth device 140, the first device 110 may send the Xn handover request confirmation message together with the obtained Xn forwarding address.

[0069] Furthermore, the first device 110 may deliver the Xn forwarding address obtained (225) to the fourth device 140 during the F1 UE context establishment process. For example, the first device 110 may deliver the Xn forwarding address obtained (225) to the fourth device 140 via an F1 UE context establishment request message.

[0070] Upon receiving an F1 UE context establishment request message from the first device 110, the fourth device 140 may trigger the establishment of an F1-U forwarding tunnel. During this process, the fourth device 140 may send an F1 distribution establishment request message (230) to the first device 110, which includes its F1-U DU address for the F1-U forwarding tunnel and the Xn forwarding address received from the first device 110 in action 225.

[0071] Since the first device 110 has newly received both the Xn forwarding address and the F1-U DU address for establishing the F1-U forwarding tunnel sent by the fourth device 140, the first device 110 can send the F1-U DU address for establishing the F1-U forwarding tunnel together with the Xn forwarding address to the third device 130, for example, in an E1 BC bearer context modification request message.

[0072] Upon receiving both the F1-U DU address and the Xn forwarding address, the third device 130 can bind the Xn forwarding address to the F1-U DU address (240). That is, a one-to-one mapping is established between the Xn forwarding address and the F1-U DU address of the fourth device 140 for the establishment of the F1-U forwarding tunnel.

[0073] Then, the third device 130 may send (245) the E1 BC bearer context modification response message to the first device 110. Then, the first device 110 sends (250) the F1 distribution establishment response message to the fourth device 140, both of which include the target CU UP F1-U address for completing the distribution establishment process (i.e., the F1-U tunnel establishment process).

[0074] The solution proposed in this disclosure optimizes handover latency compared to the 3GPP solution. The source CU CP does not need to obtain information from the source CU UP before sending the Xn handover request. Furthermore, the Xn handover request acknowledgment is sent to the source gNB very early (before the target DU establishes the F1-U forwarding tunnel), enabling the source gNB to receive the Xn handover request acknowledgment in advance and send an early RRC reconfiguration message (handover command) to the UE for faster handover execution.

[0075] Furthermore, simple logic can be implemented in the target CU-UP, establishing a one-to-one mapping between the UE's Xn forwarding tunnel and the F1-U forwarding tunnel established for the same UE. This mapping / binding can be further simplified by having the target CU-UP receive both addresses (i.e., the Xn forwarding address and the F1-U DU address) together in the same E1 BC bearer context modification request message.

[0076] Compared to another traditional method, on the one hand, the latency for handover can be optimized. The Xn handover request confirmation can be sent to the source gNB very early (before the F1 establishes the F1-U forwarding tunnel), which allows the source gNB to receive the Xn handover request confirmation in advance and send an early RRC reconfiguration (handover command) to the UE to perform the handover more quickly.

[0077] On the other hand, the simpler logic in the target CU CP directly relays the two addresses included in the target DU to the target CU UP during the establishment of the F1-U forwarding tunnel (i.e., during the F1 distribution establishment request triggered by the target DU). This avoids the requirement for the target DU to include the F1-U context reference in the F1 UE context response, and avoids the related drawback of the target CU-CP needing to parse the UE context to retrieve the UE context that previously received the F1-U reference.

[0078] Figure 3 A flowchart of an example method 300 implemented at a first device according to some example embodiments of the present disclosure is shown. For the purposes of discussion, [the following will be discussed]. Figure 1 Method 300 is described by the angle of the first device 110 in the middle.

[0079] In block 310, the first device 110 receives a request for Xn handover related to the UE from the second device.

[0080] In box 320, the first device 110 obtains the Xn forwarding address related to the Xn handover from the third device during MBS session establishment or modification, before the F1 UE context is established between the first device and the fourth device, or before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover.

[0081] At box 330, the first device 110 delivers the Xn forwarding address to at least one of the following: to the fourth device before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover; or to the second device in an acknowledgment message for the request for Xn handover before the fourth device triggers the F1-U forwarding tunnel for Xn handover and / or before the F1 UE context is established between the first device and the fourth device.

[0082] In some example embodiments, method 300 further includes: receiving, in response to the fourth device, an F1-U DU address of the fourth device established for the F1-U forwarding tunnel, together with the Xn forwarding address, and transmitting the F1-U DU address to the third device together with the Xn forwarding address.

[0083] In some example embodiments, method 300 further includes: transmitting an E1 BC bearer context establishment or modification request message to a third device as part of an MBS session establishment or modification process before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel; the E1 BC bearer context modification request message indicating a request for the Xn forwarding address; and receiving the Xn forwarding address from the third device via an E1 BC bearer context establishment / modification response message before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel.

[0084] In some example embodiments, method 300 further includes delivering the Xn forwarding address to a fourth device via an F1 UE context establishment request message.

[0085] In some example embodiments, method 300 further includes: delivering the Xn forwarding address together with a request to establish an F1-U forwarding tunnel to a fourth device via an F1 UE context establishment request message; and receiving an F1-U DU address for the F1-U forwarding tunnel from the fourth device together with the Xn forwarding address via an F1 multicast distribution establishment request message.

[0086] In some example embodiments, method 300 further includes transmitting the F1-DU address to a third device via another E1 BC bearer context modification request message, together with the Xn forwarding address.

[0087] In some example embodiments, the first device includes the CU control plane of a network device, the second device includes another network device, the third device includes the CU user plane of a network device, and the fourth device includes the DU of a network device.

[0088] Figure 4 A flowchart of an example method 400 implemented at a second device according to some example embodiments of the present disclosure is shown. For the purposes of discussion, [the following will be discussed]. Figure 1 Method 400 is described by the angle of the second device 120 in the middle.

[0089] At box 410, the second device 120 transmits a request for Xn handover related to the UE to the first device.

[0090] At box 420, before the fourth device triggers the F1-U forwarding tunnel and / or before the F1 UE context is established between the first device and the fourth device, in the confirmation message for the request for Xn handover, the second device 120 receives the Xn forwarding address associated with the Xn handover from the first device.

[0091] In some example embodiments, the first device includes the CU control plane of a network device, the second device includes another network device, and the fourth device includes the DU of a network device.

[0092] Figure 5 A flowchart of an example method 500 implemented at a third device according to some example embodiments of the present disclosure is shown. For discussion purposes, [the following will be discussed]. Figure 1 Method 500 is described by the angle of the third device 130 in the middle.

[0093] At box 510, during MBS session establishment or modification, before the F1 UE context is established between the first and fourth devices or before the fourth device triggers the establishment of the F1-U forwarding tunnel for UE-related Xn handover, the third device 130 transmits the Xn forwarding address for Xn handover to the first device.

[0094] In some example embodiments, method 500 further includes: receiving an F1-U DU address for an F1-U forwarding tunnel from a first device, together with the Xn forwarding address; and associating the Xn forwarding address with the F1-U DU address.

[0095] In some example embodiments, associating the Xn forwarding address with the F1-U DU address includes forwarding packets received via the Xn forwarding address to the received F1-U DU address.

[0096] In some example embodiments, method 500 further includes: receiving an E1 BC bearer context modification request message from the first device during MBS session establishment or modification before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover; the E1 BC bearer context modification request message indicating a request for an Xn forwarding address for Xn handover; and transmitting the Xn forwarding address to the first device via an E1 BC bearer context modification response message before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover.

[0097] In some example embodiments, method 500 further includes receiving another E1 BC bearer context modification request message from the first device, the other E1 BC bearer context modification request message containing both the F1-DU address and the Xn forwarding address.

[0098] In some example embodiments, the first means includes the CU control plane of the network device, the third means includes the CU user plane of the network device, and the fourth means includes the DU of the network device.

[0099] Figure 6A flowchart of an example method 600 implemented at a fourth device according to some example embodiments of the present disclosure is shown. For the purposes of discussion, [the following will be discussed]. Figure 1 Method 600 is described by the angle of the fourth device 140 in the fourth device.

[0100] At box 610, the fourth device 140 receives the Xn forwarding address for Xn handover from the first device before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover associated with the UE.

[0101] At frame 620, the fourth device 140, together with the Xn forwarding address, transmits the F1-U DU address of the fourth device for establishing the F1-U forwarding tunnel for Xn handover to the first device.

[0102] In some example embodiments, method 600 further includes: receiving an F1 UE context establishment request message containing an Xn forwarding address from a first device along with a request to establish an F1-U forwarding tunnel; determining an F1-U DU address for the F1-U forwarding tunnel; and transmitting an F1 multicast distribution establishment request message containing both the F1-U DU address and the Xn forwarding address to the first device.

[0103] In some example embodiments, the first device includes the CU control plane of the network device, and the fourth device includes the DU of the network device.

[0104] In some example embodiments, a first device capable of performing any method 300 (e.g., Figure 1 The first device 110 may include a component for performing the corresponding operation of method 300. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The first device may be implemented as or included in... Figure 1 In the first device 110.

[0105] In some example embodiments, the first device includes: components for receiving a request for Xn handover related to the UE from a second device; components for obtaining an Xn forwarding address related to the Xn handover from a third device during MBS session establishment or modification, before the F1 UE context is established between the first and fourth devices, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for the Xn handover; and components for delivering the Xn forwarding address to at least one of the following: delivering it to the fourth device before the fourth device triggers the establishment of an F1-U forwarding tunnel for the Xn handover; or delivering it to the second device in an acknowledgment message for the Xn handover request before the fourth device triggers the F1-U forwarding tunnel for the Xn handover and / or before the F1 UE context is established between the first and fourth devices.

[0106] In some example embodiments, the first device further includes: a component for receiving, in conjunction with the Xn forwarding address, the F1-U DU address of the fourth device established for the F1-U forwarding tunnel from the fourth device, and transmitting, in conjunction with the Xn forwarding address, the F1-U DU address to the third device.

[0107] In some example embodiments, the first apparatus further includes: a component for transmitting an E1 BC bearer context establishment or modification request message to the third apparatus as part of an MBS session modification process before the F1 UE context is established or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel, the E1 BC bearer context modification request message indicating a request for an Xn forwarding address; and a component for receiving the Xn forwarding address from the third apparatus via an E1 BC bearer context modification response message before the F1 UE context is established or before the fourth apparatus triggers the establishment of an F1-U forwarding tunnel.

[0108] In some example embodiments, the first device further includes a component for delivering the Xn forwarding address to the fourth device via an F1 UE context establishment request message.

[0109] In some example embodiments, the first device further includes: means for delivering the Xn forwarding address together with a request to establish an F1-U forwarding tunnel to the fourth device via an F1 UE context establishment request message; and means for receiving an F1-UDU address for the F1-U forwarding tunnel from the fourth device together with the Xn forwarding address via an F1 multicast distribution of the establishment request message.

[0110] In some example embodiments, the first device further includes a component for transmitting the F1-U DU address, together with the Xn forwarding address, to the third device via another E1 BC bearer context modification request message.

[0111] In some example embodiments, the first device includes the CU control plane of a network device, the second device includes another network device, the third device includes the CU user plane of a network device, and the fourth device includes the DU of a network device.

[0112] In some example embodiments, the first device further includes components for performing additional operations in some example embodiments of method 300 or the first device 110. In some example embodiments, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the first device.

[0113] In some example embodiments, a second means capable of performing any of the methods in method 400 (e.g., Figure 1The second device 120 may include a component for performing the corresponding operation of method 400. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The second device may be implemented as or included in... Figure 1 The second device 120 in the middle.

[0114] In some example embodiments, the second device includes: a component for transmitting a request for Xn handover related to the UE to the first device; and a component for receiving an Xn forwarding address related to the Xn handover from the first device in an acknowledgment message for the request for Xn handover before the fourth device triggers the F1-U forwarding tunnel and / or before the F1 UE context is established between the first device and the fourth device.

[0115] In some example embodiments, the first device includes the CU control plane of a network device, the second device includes another network device, and the fourth device includes the DU of a network device.

[0116] In some example embodiments, the second device further includes components for performing additional operations in some example embodiments of method 400 or second device 120. In some example embodiments, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the second device.

[0117] In some example embodiments, a third means capable of performing any of the methods in method 500 (e.g., Figure 1 The third device 130 may include a component for performing the corresponding operation of method 500. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The third device may be implemented as or included in... Figure 1 The third device 130 in the middle.

[0118] In some example embodiments, the third device includes a component for transmitting an Xn forwarding address for Xn handover to the first device during MBS session establishment or modification, before the F1 UE context is established between the first and fourth devices, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for UE-related Xn handover.

[0119] In some example embodiments, the third device further includes: a component for receiving, together with the Xn forwarding address, an F1-U DU address for the F1-U forwarding tunnel from the first device; and a component for associating the Xn forwarding address with the F1-U DU address.

[0120] In some example embodiments, associating the Xn forwarding address with the F1-U DU address includes forwarding packets received via the Xn forwarding address to the received F1-U DU address.

[0121] In some example embodiments, the third device further includes: a component for receiving an E1BC bearer context modification request message from the first device during MBS session establishment or modification before the F1 UE context is established or before the fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover, the E1BC bearer context modification request message indicating a request for an Xn forwarding address for Xn handover; and a component for transmitting the Xn forwarding address to the first device via an E1BC bearer context modification response message before the F1 UE context is established or before the fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover.

[0122] In some example embodiments, the third device further includes a component for receiving another E1 BC bearer context modification request message from the first device, the other E1 BC bearer context modification request message containing both the F1-DU address and the Xn forwarding address.

[0123] In some example embodiments, the first means includes the CU control plane of the network device, the third means includes the CU user plane of the network device, and the fourth means includes the DU of the network device.

[0124] In some example embodiments, the third device further includes components for performing additional operations in some example embodiments of method 500 or third device 130. In some example embodiments, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the third device.

[0125] In some example embodiments, a fourth means capable of performing any of the methods in method 600 (e.g., Figure 1 The fourth device 140 may include a component for performing a corresponding operation of method 600. This component may be implemented in any suitable form. For example, the component may be implemented in a circuit system or a software module. The fourth device may be implemented as or included in... Figure 1 The fourth device 140 in the middle.

[0126] In some example embodiments, the fourth device includes: a component for receiving an Xn forwarding address for Xn handover from the first device before the fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with the UE; and a component for transmitting, together with the Xn forwarding address, the F1-UDU address of the fourth device for the establishment of the F1-U forwarding tunnel for Xn handover to the first device.

[0127] In some example embodiments, the fourth device further includes: a component for receiving an F1 UE context establishment request message containing an Xn forwarding address from the first device, together with a request to establish an F1-U forwarding tunnel; a component for determining an F1-U DU address for the F1-U forwarding tunnel; and a component for transmitting an F1 multicast distribution establishment request message containing both the F1-U DU address and the Xn forwarding address to the first device.

[0128] In some example embodiments, the first device includes the CU control plane of the network device, and the fourth device includes the DU of the network device.

[0129] In some example embodiments, the fourth device further includes components for performing additional operations in some example embodiments of method 600 or the fourth device 140. In some example embodiments, the components include at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause execution of the fourth device.

[0130] Figure 7 This is a simplified block diagram of a device 700 suitable for implementing exemplary embodiments of the present disclosure. Device 700 can be provided to implement a communication device, such as... Figure 1 The first device 110, the second device 120, the third device 130, or the fourth device 140 are shown. As shown, the device 700 includes one or more processors 710, one or more memories 720 coupled to the processors 710, and one or more communication modules 740 coupled to the processors 710.

[0131] Communication module 740 is used for bidirectional communication. Communication module 740 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interface can represent any interface necessary for communication with other network elements. In some example embodiments, communication module 740 may include at least one antenna.

[0132] As a non-limiting example, processor 710 can be any type suitable for a local technology network and can include one or more of the following as non-limiting examples: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and processor based on a multi-core processor architecture. Device 700 can have multiple processors, such as application-specific integrated circuit chips that are time-dependent on a clock synchronized with the main processor.

[0133] Memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 724, electrically programmable read-only memory (EPROM), flash memory, hard disk, miniature optical disc (CD), digital video disc (DVD), optical disc, laser disc, and other magnetic and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 722 and other volatile memories that will not be maintained during power outages.

[0134] Computer program 730 includes computer-executable instructions that are executed by an associated processor 710. The instructions of program 730 may include instructions for performing operations / actions of some example embodiments of this disclosure. Program 730 may be stored in memory, such as ROM 724. Processor 710 can perform any suitable actions and processes by loading program 730 into RAM 722.

[0135] Example embodiments of this disclosure can be implemented by means of program 730, so that device 700 can perform as described in the reference. Figures 2 to 6 Any process discussed in this disclosure. Exemplary embodiments of this disclosure may also be implemented by hardware or by a combination of software and hardware.

[0136] In some example embodiments, program 730 may be tangibly included in a computer-readable medium, which may be included in device 700 (e.g., in memory 720) or other storage device accessible to device 700. Device 700 may load program 730 from the computer-readable medium into RAM 722 for execution. In some example embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. As used herein, the term "non-transitory" refers to a limitation on the medium itself (i.e., tangible, not tactile) rather than a limitation on data storage persistence (e.g., RAM vs. ROM).

[0137] Figure 8 An example of a computer-readable medium 800 is shown, which may be in the form of a CD, DVD, or other optical storage disc. The computer-readable medium 800 stores a program 730 thereon.

[0138] In general, the various embodiments of this disclosure can be implemented in hardware or dedicated circuitry, software, logic, or any combination thereof. Some aspects can be implemented in hardware, while others can be implemented in firmware or software executed by a controller, microprocessor, or other computing device. Although various aspects of the embodiments of this disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that the blocks, apparatuses, systems, techniques, or methods described herein can be implemented in hardware, software, firmware, dedicated circuitry or logic, general-purpose hardware or controllers or other computing devices, or some combination thereof, as examples of non-limiting examples.

[0139] Some exemplary embodiments of this disclosure also provide at least one computer program product tangibly stored on a computer-readable medium (such as a non-transitory computer-readable medium). The computer program product includes computer-executable instructions, such as those included in a program module, which are executed in a device on a target physical or virtual processor to perform any of the methods described above. Typically, a program module includes routines, programs, libraries, objects, classes, components, data structures, etc., that perform a particular task or implement a particular abstract data type. The functionality of the program module can be combined or split as needed among program modules in various embodiments. The machine-executable instructions for the program module can execute in a local device or a distributed device. In a distributed device, the program module can reside in both local storage media and remote storage media.

[0140] Program code for implementing the methods of this disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that, when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0141] In the context of this disclosure, computer program code or related data may be carried on any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, etc.

[0142] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable media can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any suitable combination thereof. More specific examples of computer-readable storage media include electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable optical disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0143] Furthermore, although the operations are described in a specific order, this should not be construed as requiring that they be performed in the specific order shown or sequentially, or that all the operations shown be performed in order to achieve the desired result. In some cases, multitasking and parallel processes can be advantageous. Similarly, while several specific implementation details are included in the foregoing discussion, they should not be considered as limiting the scope of this disclosure, but rather as a description of features that may be specific to certain embodiments. Unless explicitly stated otherwise, certain features described in the context of a single embodiment may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated otherwise, the various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0144] Although this disclosure has been described in language specific to structural features and / or methodological actions, it should be understood that the disclosure as defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A first device, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the first device to at least: Receive a request for Xn handover related to the user equipment (UE) from the second device; During the establishment or modification of a multicast and broadcast system MBS session, before the F1 UE context is established between the first and fourth devices, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for the Xn handover, the Xn forwarding address associated with the Xn handover is obtained from the third device. as well as The Xn forwarding address is delivered to at least one of the following: Delivered to the fourth device before the fourth device triggers the establishment of the F1-U forwarding tunnel for the Xn handover; or Before the fourth device triggers the F1-U forwarding tunnel for the Xn handover and / or before the F1 UE context is established between the first device and the fourth device, the confirmation message for the request for the Xn handover is delivered to the second device.

2. The first device according to claim 1, wherein the first device is configured to: In response to receiving the F1-U Distributed Unit (DU) address of the fourth device for establishing the F1-U forwarding tunnel, together with the Xn forwarding address, the F1-U DU address is transmitted to the third device together with the Xn forwarding address.

3. The first device according to claim 1 or 2, wherein the first device is configured to: Before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel, as part of the MBS session establishment or modification process, an E1 BC bearer context modification request message is transmitted to the third device, the E1 BC bearer context modification request message indicating a request for the Xn forwarding address; and Before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel, the Xn forwarding address is received from the third device via the E1 BC bearer context modification response message.

4. The first device according to any one of claims 1 to 3, wherein the first device is configured to: The Xn forwarding address is delivered to the fourth device via the F1 UE context establishment request message.

5. The first device according to any one of claims 1 to 4, wherein the first device is configured such that: The Xn forwarding address, along with a request to establish an F1-U forwarding tunnel, is delivered to the fourth device via the F1 UE context establishment request message; and The F1-U DU address for the F1-U forwarding tunnel is received from the fourth device via an F1 distribution establishment request message, together with the Xn forwarding address.

6. The first device according to claim 5, wherein the first device is configured to: The F1-DU address is transmitted to the third device via another E1 BC bearer context modification request message, together with the Xn forwarding address.

7. The first apparatus according to any one of claims 1 to 6, wherein the first apparatus includes a centralized unit (CU) control plane of a network device, the second apparatus includes another network device, the third apparatus includes a CU user plane of the network device, and the fourth apparatus includes a DU of the network device.

8. A second device, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the second device to at least: Transmit a request for Xn handover related to the user equipment (UE) to the first device; as well as Before the fourth device triggers the F1-U forwarding tunnel and / or before the F1 UE context is established between the first device and the fourth device, the Xn forwarding address associated with the Xn handover is received from the first device in the confirmation message for the request for the Xn handover.

9. The second apparatus of claim 8, wherein the first apparatus includes a centralized unit (CU) control plane of a network device, the second apparatus includes another network device, and the fourth apparatus includes a DU of the network device.

10. A third device, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the second device to at least: During the establishment or modification of a multicast and broadcast system MBS session, before the F1 UE context is established between the first device and the fourth device or before the fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with the user equipment UE, the Xn forwarding address for the Xn handover is transmitted to the first device.

11. The third device according to claim 10, wherein the third device is configured to: Together with the Xn forwarding address, receive from the first device the F1-U Distributed Unit (DU) address for the F1-U forwarding tunnel; and Associate the Xn forwarding address with the F1-U DU address.

12. The third apparatus of claim 10 or 11, wherein associating the Xn forwarding address with the F1-U address comprises: The packets received through the Xn forwarding address are forwarded to the received F1-U DU address.

13. The third device according to any one of claims 10 to 12, wherein the third device is configured to: Before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel for the Xn handover, during the MBS session establishment or modification, an E1 BC bearer context modification request message is received from the first device, the E1 BC bearer context modification request message indicating a request for the Xn forwarding address for the Xn handover; and Before the F1 UE context is established or before the fourth device triggers the establishment of the F1-U forwarding tunnel for the Xn handover, the Xn forwarding address is transmitted to the first device via an E1 BC bearer context modification response message.

14. The third device according to any one of claims 10 to 13, wherein the third device is made to: The first device receives another E1 BC bearer context modification request message, which includes both the F1-DU address and the Xn forwarding address.

15. The third device according to any one of claims 10 to 14, wherein the first device includes a centralized unit (CU) control plane of the network device, the third device includes a CU user plane of the network device, and the fourth device includes a DU of the network device.

16. A fourth device, comprising: At least one processor; as well as At least one memory stores instructions that, when executed by the at least one processor, cause the fourth device to at least: Before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover related to the user equipment (UE), the Xn forwarding address for the Xn handover is received from the first device. as well as Together with the Xn forwarding address, the F1-U distributed unit (DU) address of the fourth device, which is used for the Xn handover, is transmitted to the first device.

17. The fourth device according to claim 16, wherein the fourth device is configured to: Along with the request to establish an F1-U forwarding tunnel, an F1 UE context establishment request message containing the Xn forwarding address is received from the first device; Determine the F1-U DU address for the F1-U forwarding tunnel; and Transmit an F1 distribution establishment request message containing both the F1-DU address and the Xn forwarding address to the first device.

18. The fourth device according to claim 16 or 17, wherein the first device includes a centralized unit (CU) control plane of the network device, and the fourth device includes the DU of the network device.

19. A method comprising: The first device receives a request for Xn handover related to the user equipment (UE) from the second device. During the establishment or modification of a multicast and broadcast system MBS session, before the F1 UE context is established between the first and fourth devices, or before the fourth device triggers the establishment of an F1-U forwarding tunnel for the Xn handover, the Xn forwarding address associated with the Xn handover is obtained from the third device. as well as The Xn forwarding address is delivered to at least one of the following: Delivered to the fourth device before the fourth device triggers the establishment of the F1-U forwarding tunnel for the Xn handover; or Before the fourth device triggers the F1-U forwarding tunnel for the Xn handover and / or before the F1 UE context is established between the first device and the fourth device, the confirmation message for the request for the Xn handover is delivered to the second device.

20. A method comprising: The second device transmits a request for Xn handover related to the user equipment (UE) to the first device; as well as Before the fourth device triggers the F1-U forwarding tunnel and / or before the F1 UE context is established between the first device and the fourth device, the Xn forwarding address associated with the Xn handover is received from the first device in the confirmation message for the request for the Xn handover.

21. A method comprising: During the establishment or modification of a multicast and broadcast system MBS session, before the F1 UE context is established between the first and fourth devices or before the fourth device triggers the establishment of an F1-U forwarding tunnel for Xn handover associated with the user equipment UE, the Xn forwarding address for the Xn handover is transmitted from the third device to the first device.

22. A method comprising: Before the fourth device triggers the establishment of the F1-U forwarding tunnel for Xn handover associated with the user equipment (UE), the Xn forwarding address for the Xn handover is received from the first device at the fourth device. as well as Together with the Xn forwarding address, the F1-U distributed unit (DU) address of the fourth device, which is used for the Xn handover, is transmitted to the first device.

23. A computer-readable medium comprising instructions stored thereon, the instructions being configured to cause a device to perform at least the method of claim 19, the method of claim 20, the method of claim 21, or the method of claim 22.

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