User plane relocation of multicast sessions in centralized units

Abstract

Techniques are described for relocating at least one multicast (MC) session from a first CU-UP (CU-UP1) to a second CU-UP (CU-UP2). In operation, an MC bearer context setup request for relocating at least one MC session is received, where the at least one MC session exists between the CU-UP1 and one or more DUs. The bearer context setup request includes a first list of transport network layer addresses (TNLAs) associated with one or more DUs. In response to the MC bearer context setup request, an MC bearer context setup response including a second list of CU TNLAs is received, where the second list of CU TNLAs is associated with the CU-UP2, and the second list of CU TNLAs corresponds to the first list of TNLAs.

Description

Background Technology

[0001] Cellular networks facilitate the establishment of connections and the sharing of information among multiple user equipments (UEs) connected to them. A cellular network comprises multiple interconnected nodes that facilitate the establishment of connections and routing information among the multiple UEs. For example, if data is to be sent from a first UE connected to the cellular network to a second UE also connected to the cellular network, the data is first sent from the first UE to a base station serving the first UE, whereby the base station further forwards the data to the core network. The core network then identifies another base station serving the second UE and sends the data to that other base station, which then forwards the data to the second UE. Attached Figure Description

[0002] The following detailed embodiments refer to the accompanying drawings, in which:

[0003] Figure 1A The illustration shows an example of a next-generation radio access network (NG-RAN) including a gNodeB, according to this topic.

[0004] Figure 1B The diagram illustrates a gNodeB based on an example from this topic.

[0005] Figure 2 The diagram illustrates the control plane (CU-CP) of a centralized unit included in a gNodeB according to an example of this topic.

[0006] Figure 3 The illustration shows the second user plane (CU-UP2) of a centralized unit according to an example of this topic.

[0007] Figure 4 The illustration shows the distributed units (DUs) included in a gNodeB according to an example of this topic.

[0008] Figure 5 The illustration shows an example of a CU-CP communicating with one or more DUs, CU-UP1, and CU-UP2 according to this topic to facilitate the relocation of at least one MC session from CU-UP1 to CU-UP2.

[0009] Figure 6 The diagram illustrates an example call flow for relocating at least one MC session from CU-UP1 to CU-UP2, based on this topic.

[0010] Figure 7 and Figure 8 The illustration shows a method implemented by CU-CP, according to an example in this topic, for relocating an MC session from CU-UP1 to CU-UP2.

[0011] Figure 9 and Figure 10The diagram illustrates a method implemented by CU-UP2, according to an example from this topic, for relocating an MC session from CU-UP1 to CU-UP2, and

[0012] Figure 11 The illustration shows a method implemented by DU, based on an example from this topic, for relocating an MC session from CU-UP1 to CU-UP2.

[0013] Throughout the accompanying drawings, the same reference numerals denote similar but not necessarily identical elements. The drawings provide examples and / or implementations consistent with the specification; however, this specification is not limited to the examples and / or implementations provided in the drawings. Detailed Implementation

[0014] To initiate data transmission from the UE to the core network via the base station, a communication link is typically established between the UE and the base station. The establishment of this communication link is facilitated by various physical and logical entities included in the base station. For example, when the cellular network is a fifth-generation (5G) cellular network, the base station (i.e., gNodeB) includes various entities such as a centralized unit and multiple distributed units (DUs) coupled to the centralized unit to facilitate the establishment of the communication link and data transmission between the UE and the gNodeB.

[0015] In operation, data is sent from the UE to various DUs at the gNodeB, and upon receiving the data, the DU forwards it to a centralized unit, which then transmits the data to the core network. The centralized unit may include different planes to handle data transmission to the core network (i.e., the 5G core (5GC)). Specifically, the centralized unit may include a control plane (CU-CP) and multiple user planes (CU-UPs), where the CU-CP and multiple CU-UPs handle control layer signaling and user data signaling, respectively, to transmit data to the 5GC. In operation, the DU establishes a session with one of the multiple CU-UPs and transmits data to the CU-UP, which is then transmitted to the 5GC. The establishment of the session between the DU and the CU-UP, and the subsequent transmission of data from the DU to the CU-UP, are typically facilitated and controlled by the CU-CP. A CU-UP may be coupled to an individual DU or multiple DUs. In one example, when a CU-UP is connected to an individual DU, the CU-UP may establish a unicast session, while when a CU-UP is simultaneously connected to multiple DUs, it can be said that the CU-UP has established a multicast (MC) session.

[0016] A situation may arise where a session existing between a DU and a CU-UP (e.g., the first CU-UP) may need to be relocated to another CU-UP (e.g., the second CU-UU). This could occur, for example, when resource utilization associated with a session existing between the first CU-UP and multiple DUs reaches a threshold requiring load balancing at the first CU-UP. It could also occur if the first CU-UP fails.

[0017] While unicast sessions between CU-UP and DU can be relocated from one CU-UP to another without interruption, known mechanisms for relocating MC sessions involve disconnecting the individual sessions between the first CU-UP and each of the multiple DUs, and then reconstructing the individual sessions between the other CU-UP and each of the multiple DUs. Because the known mechanisms for relocating MC sessions from the first CU-UP to the second CU-UP involve disconnecting and reconstructing individual sessions, such mechanisms generally involve disruption and significant delays in MC session relocation.

[0018] Based on the examples in this topic, a technique for relocating at least one MC session from a first CU-UP (CU-UP1) to a second CU-UP (CU-UP2) is described.

[0019] In the example implementation, an MC bearer context establishment request is received for relocating at least one MC session from CU-UP1 to CU-UP2, wherein at least one MC session exists between CU-UP1 and one or more DUs. The MC bearer context establishment request includes a first list of Transport Network Layer Addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs. In response to the MC bearer context establishment request, an MC bearer context establishment response is received. The MC bearer context establishment response includes a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with CU-UP2. Furthermore, each CU TNLA corresponds to a TNLA included in the first list of TNLAs. The second list of CU TNLAs can then be sent to the DU for relocating at least one MC session to CU-UP2.

[0020] In one example, an MC bearer context establishment request is sent from the control plane of the centralized unit (CU-CP) to CU-UP2. In this example, upon receiving the MC bearer context establishment request, CU-UP2 generates a second list of CU TNLAs. Then, CU-UP2 sends an MC bearer context response, including the second list of CU TNLAs, to CU-CP.

[0021] Providing a second list of CU TNLAs for each of the one or more DUs involved in at least one MC session for relocating at least one MC session from CU-UP1 to CU-UP2 enables one or more DUs to initiate relocation of at least one MC session simultaneously. This reduces the latency involved in the relocation of at least one MC session.

[0022] Please refer to Figure 1 to... Figure 8 The implementation of the example computing device is explained in detail. While aspects of the described computing device can be implemented in any number of different electronic devices, environments, and / or implementations, these examples are described within the context of the following example device(s). It should be noted that the accompanying drawings of this subject matter are for illustrative purposes and should not be construed as limiting the scope of the claimed subject matter.

[0023] Figure 1A The illustration shows an example of a next-generation (NG) radio access network (RAN) 100 including gNodeB 102 according to this subject matter. In one example, in addition to gNodeB 102, the NG-RAN may also include at least one other gNodeB, such as gNodeB 104. gNodeB 102 may be coupled to gNodeB 104 via an Xn interface. Furthermore, each of gNodeB 102 and gNodeB 104 may be coupled to a fifth-generation core (5GC) 106 via an NG interface. In one example, gNodeB 102 may include a centralized unit 108 and multiple distributed units (DUs), such as DU 110-1 and DU 110-2. The centralized unit 108 may be communicatively coupled to each of DU 110-1 and 110-2, wherein the communication coupling is performed via an F1 interface.

[0024] Centralized unit 108 can be a physical or logical node used to control the operation of each DU in DU 110-1 and 110-2. Furthermore, centralized unit 108 can host Radio Resource Control (RRC) protocol, Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP). Additionally, each DU in DU 110-1 and DU 110-2 can be a physical or logical node whose operation is partially controlled by centralized unit 108. Furthermore, each DU in DU 110-1 and 110-2 can host the Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and physical layer of the gNodeB.

[0025] Figure 1B The diagram illustrates another example of gNodeB 102 based on this topic. (See diagram for example.) Figure 1BAs shown, the centralized unit 108 included in gNodeB 102 may include a control plane (CU-CP) 112 and one or more user planes, such as CU-UP1114-1 and CU-UP2 114-2.

[0026] CU-CP 112 can be a physical or logical node included in the centralized unit and can host the RRC and control plane portions of the PDCP of the centralized unit 108. Furthermore, each of CU-UP1 114-1 and CU-UP2 114-2 can be a physical or logical node included in the centralized unit 108 and can host the user plane portion and SDAP of the PDCP of the centralized unit 108.

[0027] CU-CP 112 can be communicatively coupled to each of CU-UP1 114-1 and CU-UP2 114-2, with the communication coupling occurring via an E1 interface. In one example, CU-CP 112 can control the establishment of a session between DU 110-1 and 110-2 and one of the CU-UP1 114-1 and CU-UP2 114-2, as well as the subsequent transmission of data from DU 110-2 and 110-1 to CU-UP1 114-1 or CU-UP2 114-2.

[0028] In one example, each of DU 110-1 and 110-2 can be communicatively coupled to CU-UP1 114-1, where communication coupling is provided via an F1-U interface. In this example, each of DU 110-1 and 110-2 can also be communicatively coupled to CU-CP 112, where communication coupling is performed via an F1-C interface.

[0029] In operation, when data needs to be transmitted from 5GC 106 to DU 110-1 and 110-2 and further to user equipment, a multicast (MC) session can be established between CU-UP1 114-1 and DU 110-2 via the F1-U interface. Upon receiving data from 5GC 106, CU-UP1 114-1 can send the data to DU 110-1 and 110-2.

[0030] It is possible for resource utilization at CU-UP1 114-1 to exceed a threshold. In one example, resource utilization may exceed the threshold when data traffic associated with one or more MC sessions exceeds a pre-specified limit. In another example, resource utilization may exceed the threshold when the count of MC sessions existing between DU 110-1 and 110-2 and CU-UP1 114-1 exceeds a pre-specified count.

[0031] In one example, when the resource utilization at CU-UP1 114-1 exceeds a threshold, CU-UP1 may send a session relocation indication to CU-CP 112 to relocate one or more MC sessions from CU-UP1 114-1 to CU-UP2 114-2. In one example, the session relocation indication may include a first list of Transport Network Layer Addresses (TNLAs), where each TNLA in the first list is associated with one or more DUs in DUs 110-1 and 110-2. In this case, CU-CP 112 may initiate a procedure to relocate one or more MC sessions from CU-UP1 to CU-UP2. It should be noted that although the sending of the session relocation indication by CU-UP1 when the resource utilization at CU-UP1 114-1 exceeds a threshold has been described, CU-UP1 114-1 may also send the session relocation indication in other situations, and for brevity, details relating to these situations are not included herein. The accompanying drawings illustrate a method for relocating one or more MC sessions from CU-UP1 to CU-UP2.

[0032] Figure 2 The illustration shows an example of CU-CP 112 based on this topic.

[0033] CU-CP 112 may include CU-CP processor 202. In one example, CU-CP processor 202 can retrieve and execute data stored in memory. Figure 2 The computer-readable instruction 204 (not shown) facilitates the relocation of at least one multicast (MC) session from CU-UP1 114-1 to CU-UP2 114-2, among other functions. In one example, at least one MC session may exist between CU-UP1 114-1 and one or more DU 110-1 and 110-2.

[0034] In the example implementation, in order to relocate at least one MC session from CU-UP1 114-1 to CU-UP2 114-2, processor 202 may cause CU-CP 112 to send a multicast (MC) bearer context establishment request to CU-UP2 114-2 for relocating at least one MC session from CU-UP1 114-1 to CU-UP2 114-2. The MC bearer context establishment request may include a first list of TNLAs, wherein each TNLA in the first list of TNLAs is associated with one or more DUs in DUs 110-1 and 110-2.

[0035] In one example, processor 202 can cause CU-CP 112 to send an MC bearer context establishment request under various circumstances. For example, in one example, processor 202 can cause CU-CP 112 to send an MC bearer context establishment request upon receiving a session relocation indication for relocating an MC session. In this example, the session relocation indication for relocating an MC session can be received from CU-UP1 114-1.

[0036] In another example, processor 202 may cause CU-CP 112 to send an MC bearer context establishment request based on a load indicator received from CU-UP1 114-1. In one example, the load indicator may indicate a count of one or more MC sessions existing between CU-UP1 1114-1 and multiple DUs 110-1 and 110-2, wherein the one or more sessions may include at least one MC session. Processor 202 may then cause CU-CP 112 to determine that the count of one or more MC sessions exceeds a threshold. Based on this determination, processor 202 may cause CU-CP 112 to trigger transmission for relocating the bearer context establishment request for at least one MC session. In another example, the load indicator may indicate the MC data traffic volume of at least one MC session. Processor 202 may then cause CU-CP 112 to determine that the MC data traffic volume exceeds a threshold. Based on this determination, processor 202 may cause CU-CP 112 to trigger transmission for relocating the bearer context establishment request for at least one MC session.

[0037] The CU-CP processor 202 can then cause the CU-CP 200 to receive an MC bearer context establishment response, wherein the MC bearer context establishment response can be received in response to an MC bearer context establishment request. In one example, the MC bearer context establishment response may include a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs corresponds to a TNLA in the first list of TNLAs. Furthermore, each CU TNLA in the second list of CU TNLAs is associated with CU-UP2 114-2.

[0038] Subsequently, processor 202 can cause a second list of CU TNLAs to be sent to one or more DUs 110-1 and 110-2. The second list of CU TNLAs can be sent to one or more DUs to facilitate the relocation of at least one MC session from CU-UP1 114-1 to CU-UP2 114-2.

[0039] In another example implementation, the CU-CP processor 202 may cause CU-CP 200 to send an MC bearer context establishment request to CU-UP2 for relocating at least one MC session from CU-UP1 to CU-UP2. As previously described, at least one MC session may exist between CU-UP1 and one or more distributed units (DUs). The CU-CP processor 202 may then cause CU-CP 200 to send an MC bearer context modification request to CU-UP2 including a first list of TNLAs, wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs 110-1 and 110-2.

[0040] The CU-CP processor 202 can then cause the CU-CP 200 to receive an MC bearer context modification response from the CU-UP2 114-2 in response to the MC bearer context modification request. The MC bearer context modification response may include a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2 114-2, and each CU TNLA corresponds to a TNLA included in a first list of TNLAs. The CU-CP processor 202 can then cause the CU-CP 200 to send the second list of CU TNLAs to one or more DUs 110-1 and 110-2 for relocating at least one MC session to the CU-UP2 114-2.

[0041] Figure 3 The illustration shows an example of a CU-UP2 114-2 according to this topic. The CU-UP2 114-2 may include a processor 302. In one example, the processor 302 may retrieve and execute data stored in memory (…). Figure 2 The computer-readable instruction 304 (not shown) facilitates the relocation of at least one MC session from CU-UP1 114-1 to CU-UP2 114-2, among other functions. As previously described, at least one MC session may exist between CU-UP1 114-1 and one or more DU 110-1 and 110-2.

[0042] In the example implementation, processor 302 may cause CU-UP2 114-2 to receive from CU-CP 112 an MC bearer context establishment request for relocating at least one MC session from CU-UP1 114-1 to CU-UP2 114-2. In one example, the MC bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with one or more DUs in DUs 110-1 and 110-2.

[0043] In response to receiving an MC bearer context establishment request, processor 302 may cause CU-UP2 114-2 to generate a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs corresponds to a TNLA in the first list of TNLAs. Furthermore, each CU TNLA in the second list of CU TNLAs is associated with CU-UP2 114-2. In this example, the second list of CU TNLAs may be used to relocate at least one MC session to CU-UP2 114-2. Processor 302 may then cause CU-UP2 114-2 to send an MC bearer context response to CU-CP 112 in response to the bearer context request. In one example, the MC bearer context response may include the second list of CU TNLAs.

[0044] In another exemplary implementation, processor 302 may cause CU-UP2 114-2 to receive from the control plane (CU-CP) of the centralized unit a multicast (MC) bearer context establishment request for relocating at least one MC session from the first user plane (CU-UP1) of the centralized unit to CU-UP2, wherein at least one MC session exists between CU-UP1 and one or more distributed units (DUs). Processor 302 may then cause CU-UP2 114-2 to receive from the CU-CP an MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs.

[0045] Subsequently, processor 302 can cause CU-UP2 114-2 to generate a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with CU-UP2. Furthermore, each CU TNLA corresponds to a TNLA included in the first list of TNLAs. In one example, the second list of CU TNLAs is used to relocate at least one MC session to CU-UP2. Processor 302 can then cause CU-UP2 114-2 to send an MC bearer context modification response, including the second list of CU TNLAs, to CU-CP in response to a bearer context modification request.

[0046] Figure 4 The illustration shows an example of DU 110-1 based on this topic.

[0047] DU 110-1 may include processor 402. In one example, processor 402 may retrieve and execute data stored in memory. Figure 2The computer-readable instruction 404 (not shown) facilitates the relocation of at least one MC session from CU-UP1114-1 to CU-UP2 114-2, among other functions. The MC session may exist between CU-UP1 114-1 and DU 110-1.

[0048] In operation, processor 402 can cause DU 110-1 to receive an MC distribution modification request for relocating at least one MC session from CU-UP1114-1 to CU-UP2 114-2. The MC distribution modification request includes a first list of Transport Network Layer Addresses (TNLAs), wherein each TNLA in the first list includes a DU TNLA associated with DU 110-1 or a CU TNLA associated with CU-UP1. The MC distribution modification request may also include a second list of CUTNLAs associated with CU-UP2 114-2. The second list of CU TNLAs may include CUTNLAs corresponding to the TNLAs in the first list of TNLAs. In one example, the second list of CU TNLAs can be used to relocate the MC session to CU-UP2 114-2. Processor 402 can then cause DU 110-1 to relocate the MC session to CU-UP2 114-2 based on the second list of CU TNLAs.

[0049] Figure 5 The illustration shows an example of CU-CP 112 communicating with DU 110-1 and 110-2, CU-UP1 114-1 and CU-UP2 114-2 according to this topic.

[0050] In one example, CU-CP 112 can be communicatively coupled to CU-UP1 114-1. CU-CP 112 can also be communicatively coupled to CU-UP1 via an E1 interface. Furthermore, CU-CP 112 can be communicatively coupled to each of DUs 110-1 and 110-2 via an F1-U interface. Additionally, each of DUs 110-1 and 110-2 can be communicatively coupled to CU-UP1 via an F1-U interface.

[0051] CU-CP 112 may include CU-CP processor 202, CU-CP memory 502 coupled to CU-CP processor 202, and CU-CP interface 504 coupled to CU-CP memory 504. The functionality of the various elements shown in the figures (including any functional blocks labeled "processor") can be provided using dedicated hardware and hardware capable of executing instructions. When provided by a processor, these functions can be provided by a single dedicated processor, a single shared processor, or multiple individual processors, some of which may share the functionality. Furthermore, the explicit use of the term "processor" should not be construed as referring only to hardware capable of executing instructions; it may implicitly include, but is not limited to, digital signal processor (DSP) hardware, network processors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). Other standard and / or custom hardware may also be coupled to CU-CP processor 202.

[0052] CU-CP memory 502 may be a computer-readable medium, examples of which include volatile memory (e.g., RAM) and / or non-volatile memory (e.g., erasable programmable read-only memory (i.e., EPROM), flash memory, etc.). CU-CP memory 502 may be external or internal memory, such as a flash drive, optical disc drive, external hard disk drive, etc. CU-CP memory 502 may also include data that can be used or generated during the operation of CU-CP 112.

[0053] The CU-CP interface 504 allows the CU-CP 112 to be connected or coupled to one or more other devices via a wired connection (e.g., a local area network, i.e., LAN) or a wireless connection (e.g., Bluetooth®, Wi-Fi). The CU-CP interface 504 also enables communication between different logical and hardware components of the CU-CP 112.

[0054] CU-CP 112 may also include CU-CP data 506 that can be used or generated by processor 202 in performing various functions. In one example, data 506 includes a first TNLA 508, a second TNLA 510, a relocation instruction 512, and other data 514. Among other things, the other data 514 may be used as a repository for storing data that is processed, received, or generated as processor 202 executes instructions.

[0055] Turning to CU-UP1 114-1, CU-UP1 114-1 may include a CU-UP1 processor 516, a CU-UP1 memory 518 coupled to the CU-UP1 processor 516, and a CU-UP1 interface 520 coupled to the CU-UP1 memory 518. The functionality of the various elements shown in the figure (including any functional blocks labeled "processor") can be provided using dedicated hardware as well as hardware capable of executing instructions. When provided by a processor, these functions can be provided by a single dedicated processor, a single shared processor, or multiple individual processors, some of which may share the functionality. Furthermore, the explicit use of the term "processor" should not be construed as referring only to hardware capable of executing instructions; it may implicitly include, but is not limited to, digital signal processor (DSP) hardware, network processors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). Other standard and / or custom hardware may also be coupled to the CU-UP1 processor 516.

[0056] The CU-UP1 memory 518 may be a computer-readable medium, examples of which include volatile memory (e.g., RAM) and / or non-volatile memory (e.g., erasable programmable read-only memory (i.e., EPROM), flash memory, etc.). The CU-UP1 memory 518 may be external or internal memory, such as a flash drive, optical disc drive, external hard disk drive, etc. The CU-UP1 memory 518 may also include data that can be used or generated during the operation of the CU-UP1 114-1.

[0057] The CU-UP1 interface 520 allows the CU-UP2 114-2 to be connected or coupled to one or more other devices via a wired connection (e.g., a local area network, i.e., LAN) or a wireless connection (e.g., Bluetooth®, Wi-Fi). The CU-UP1 interface 520 also enables communication between different logical and hardware components of the CU-UP1 114-1.

[0058] CU-UP1 114-1 may also include CU-UP1 data 522 that can be used or generated by the processor 516 in performing various functions. In one example, data 522 includes a first TNLA 524, a second TNLA 526, a load indication 528, and other data 530. Among other things, the other data 530 may be used as a repository for storing data that is processed, received, or generated as the processor 516 executes instructions.

[0059] The CU-UP2 114-2 may include a CU-UP2 processor 302, a CU-UP2 memory 532 coupled to the CU-UP2 processor 302, and a CU-UP2 interface 534 coupled to the CU-UP2 memory 532. The functionality of the various elements shown in the figure (including any functional blocks labeled "processor") can be provided using dedicated hardware and hardware capable of executing instructions. When provided by a processor, these functions can be provided by a single dedicated processor, a single shared processor, or multiple individual processors, some of which may share the functionality. Furthermore, the explicit use of the term "processor" should not be construed as referring only to hardware capable of executing instructions; it may implicitly include, but is not limited to, digital signal processor (DSP) hardware, network processors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). Other standard and / or custom hardware may also be coupled to the CU-UP2 processor 302.

[0060] The CU-UP2 memory 532 can be a computer-readable medium, examples of which include volatile memory (e.g., RAM) and / or non-volatile memory (e.g., erasable programmable read-only memory (i.e., EPROM), flash memory, etc.). The CU-UP2 memory 532 can be external or internal memory, such as a flash drive, optical disc drive, external hard disk drive, etc. The CU-UP2 memory 532 may also include data that can be used or generated during the operation of the CU-UP2 114-2.

[0061] The CU-UP2 interface 534 allows the CU-UP2 114-2 to be connected or coupled to one or more other devices via a wired connection (e.g., a local area network, i.e., LAN) or a wireless connection (e.g., Bluetooth®, Wi-Fi). The CU-UP1 interface 534 also enables communication between different logical and hardware components of the CU-UP2 114-2.

[0062] CU-UP2 114-2 may also include CU-UP2 data 536 that can be used or generated by the processor 302 in performing various functions. In one example, data 536 includes a first TNLA 538, a second TNLA 540, and other data 544. Among other things, the other data 544 may be used as a repository for storing data that is processed, received, or generated as the CU-UP2 processor 302 executes instructions.

[0063] Turning to DU 110-1 and 110-2, DU 110-1 may include DU processor 402, DU memory 546 coupled to DU processor 402, and DU interface 548 coupled to DU memory 546. The functionality of the various elements shown in the figures (including any functional blocks labeled "processor") can be provided using dedicated hardware as well as hardware capable of executing instructions. When provided by a processor, these functions can be provided by a single dedicated processor, a single shared processor, or multiple individual processors, some of which may share the functionality. Furthermore, the explicit use of the term "processor" should not be construed as referring only to hardware capable of executing instructions; it may implicitly include, but is not limited to, digital signal processor (DSP) hardware, network processors, application-specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs). Other standard and / or custom hardware may also be coupled to DU processor 302.

[0064] DU memory 546 may be a computer-readable medium, examples of which include volatile memory (e.g., RAM) and / or non-volatile memory (e.g., erasable programmable read-only memory (i.e., EPROM), flash memory, etc.). DU memory 546 may be external or internal memory, such as a flash drive, optical disc drive, external hard disk drive, etc. DU memory 546 may also include data that can be used or generated during operation of DU 110-1.

[0065] The DU interface 548 allows the DU 110-1 to connect or couple to one or more other devices via a wired connection (e.g., a local area network, i.e., LAN) or a wireless connection (e.g., Bluetooth®, Wi-Fi). The DU interface 548 also enables communication between different logic and hardware components of the DU 110-1.

[0066] DU 110-1 may also include DU data 550 that can be used or generated by the processor 402 in performing various functions. In one example, data 550 includes a first TNLA 552, a second TNLA 554, and other data 556. Among other things, the other data 556 may be used as a repository for storing data that is processed, received, or generated as the DU processor 402 executes instructions.

[0067] In the example implementation, the CU-UP1 processor 516 enables the CU-UP1 to establish at least one MC session with DU 110-1 and 110-2. The CU-UP1 processor 516 enables the CU-UP1 to establish at least one MC session via the F1-U interface. The CU-UP1 processor 516 can then enable the CU-UP1 to begin exchanging data with DU 110-1 and 110-2.

[0068] The CU-UP1 processor 516 can monitor resource utilization at CU-UP1. In one example, the CU-UP1 processor 516 can monitor resource utilization by monitoring MC data traffic associated with at least one MC session. In this example, the CU-UP1 processor 516 can store the MC data traffic in a load indicator 528. When the CU-UP1 processor 516 determines that the MC data traffic exceeds a threshold, the CU-UP1 processor 516 can cause CU-UP1 114-1 to send a session relocation indicator to CU-CP 112 for relocating at least one MC session from CU-UP1 114-1.

[0069] In another example, the CU-UP1 processor 516 can monitor resource utilization by monitoring the count of one or more MC sessions existing between CU-UP1 114-1 and multiple DUs. In this example, the CU-UP1 processor 516 can store the count of one or more MC sessions in a load indicator 528. When the CU-UP1 processor 516 determines that the count of one or more MC sessions existing between CU-UP1 114-1 and multiple DUs exceeds a threshold, the CU-UP1 controller 516 can cause CU-UP1 114-1 to send a session relocation indication to CU-CP 112 for relocating at least one MC session from CU-UP1 114-1.

[0070] In one example, the session relocation indication may include a first list of TNLAs, wherein the first list of TNLAs is associated with DU 110-1 and 110-2 involved in at least one MC session.

[0071] In one example, the CU-CP processor 202 can cause the CU-CP 112 to receive a session relocation indication from the CU-UP1 114-1. In this example, upon receiving the session relocation indication, the CU-CP processor 202 can cause the CU-CP 112 to set a relocation indication flag in the relocation indication 512. The CU-CP processor 202 can also cause the CU-CP 112 to store a first list of TNLAs in the first TNLA 508.

[0072] Then, CU-CP processor 202 can cause CU-CP 112 to send an MC bearer context establishment request to CU-UP2 114-2. CU-CP processor 202 can also cause CU-CP 112 to send an MC bearer context establishment request for relocating at least one MC session from CU-UP1 114-1 to CU-UP2 114-2. CU-CP processor 202 can also cause CU-CP 112 to send the MC bearer context establishment request based on the E1 Application Protocol (E1AP). In one example, the MC bearer context establishment request may include a first list of TNLAs.

[0073] In one example, CU-CP processor 202 may cause CU-CP 200 to send an MC bearer context modification request to CU-UP2 after the transmission of the MC bearer context establishment request. In this example, instead of the MC bearer context establishment request, the MC bearer context modification request may include a first list of TNLAs.

[0074] In one example, upon receiving an MC bearer context establishment request, the CU-UP2 processor 302 may determine the availability of resources for relocating the MC session to CU-UP2. If the CU-UP2 processor 302 determines that the resources for relocating at least the MC session are available at CU-UP2 114-2, the CU-UP2 processor 302 may cause CU-UP2 114-2 to store a first list of TNLAs in a first TNLA 538. The CU-UP2 processor 302 may then cause CU-UP2 114-2 to generate a second list of CUTNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with CU-UP2. Furthermore, each CUTNLA corresponds to a TNLA included in the first list of TNLAs. The CU-UP2 processor 302 may then cause CU-UP2 114-2 to store the second list of CU TNLAs in a second TNLA 540. The CU-UP2 processor 302 can then cause the CU-UP2 114-2 to send an MC bearer context establishment response to the CU-CP 112, wherein the MC bearer context establishment response may include a second list of CU TNLAs. In one example, the MC bearer context establishment response may be sent to the CU-CP 112 based on E1AP.

[0075] In another example, when the first list of TNLAs is included in the MC bearer context modification request, the CU-UP2 processor 302, upon receiving the MC bearer context modification request, can determine the availability of resources for relocating the MC session to CU-UP2. If the CU-UP2 processor 302 determines that the resources for relocating at least the MC session are available at CU-UP2 114-2, the CU-UP2 processor 302 can cause CU-UP2 114-2 to store the first list of TNLAs in a first TNLA 538. The CU-UP2 processor 302 can then cause CU-UP2 114-2 to generate a second list of CU TNLAs. The CU-UP2 processor 302 can then cause CU-UP2 114-2 to store the second list of CU TNLAs in a second TNLA 540. The CU-UP2 processor 302 can then cause CU-UP2 114-2 to send an MC bearer context modification response to CU-CP 112. In one example, the MC bearer context modification response may include the second list of CU TNLAs. In one example, an MC bearer context modification response can be sent to CU-CP 112 based on E1AP.

[0076] The CU-CP processor 202 can cause the CU-CP 112 to receive an MC bearer context establishment response or an MC bearer context modification response. Upon receiving the MC bearer context establishment response or the MC bearer context modification response, the CU-CP processor 202 can cause the CU-CP 112 to send an MC distribution modification request to each of DUs 110-1 and 110-2. The MC distribution modification request may include a first list of TNLAs and a second list of CU TNLAs. In one example, the first list of TNLAs may include DU TNLAs associated with DU 110-1 or CU TNLAs associated with CU-UP1 114-1. In this example, the second list of CU TNLAs may include CU TNLAs associated with CU-UP2. Furthermore, in this example, each CU TNLA in the second list of CU TNLAs may correspond to a TNLA in the first list of TNLAs. It should be noted that although it has been described that a second list of TNLAs is sent from CU-CP 112 to each of DU 110-1 and 110-2 in the MC distribution modification request, a first list of TNLAs may also be sent to each of DU 110-1 and 110-2 in any F1 Application Protocol (F1AP) message sent from CU-CP 112 to DU 110-1 and 110-2.

[0077] In one example, upon receiving an MC bearer context establishment response or an MC bearer context modification response from CU-UP2 114-2, CU-CP 112 may send an MC distribution modification request to 5GC (not shown). CU-CP 112 may send the MC distribution modification request to 5GC based on the NG Application Protocol (NGAP). CU-CP 112 may send the MC distribution modification request to provide 5GC with a second list of CU TNLAs to be used by 5GC to forward data associated with at least one MC session to CU-UP2 114-2. CU-CP processor 202 may then cause CU-CP 112 to receive an MC distribution modification response from 5GC in response to the MC distribution modification request.

[0078] DU processor 402 can cause DU 110-1 to receive an MC distribution modification request that includes a first list of TNLAs and a second list of CU TNLAs. In one example, DU processor 402 can cause DU 110-1 to receive the MC distribution modification request based on F1AP. Upon receiving the MC distribution modification request, DU processor 402 can store the first list of TNLAs and the second list of CU TNLAs in a first TNLA 552 and a second TNLA 554, respectively. DU processor 402 can then cause DU 110-1 to use the CU TNLAs included in the second list of CU TNLAs to relocate at least one MC session from CU-UP1 114-1 to CU-UP2 114-2.

[0079] After at least one MC session has been relocated from CU-UP1 114-1 to CU-UP2 114-2, CU-CP processor 202 can cause CU-CP 112 to send an MC bearer context modification request to CU-UP1 114-1. CU-CP processor 202 can cause CU-CP 112 to send the MC bearer context modification request based on E1AP. CU-CP processor 202 can cause CU-CP 112 to send the MC bearer context modification request to provide CU-UP1 114-1 with a second list of CU TNLAs associated with CU-UP2, so that CU-UP1 114-1 can forward any data associated with at least one MC session from 5GC to CU-UP2 114-2. The MC bearer context modification request may also include a request for the progress of the last delivered MC radio bearer (MRB) associated with CU-UP1 114-1. CU-CP processor 202 can then cause CU-CP 112 to receive an MC bearer context modification response including the progress of the last delivered MRB. In one example, the MC bearer context modification response includes the MRB progress from the last delivery of CU-UP1114-1.

[0080] Upon receiving an MC bearer context modification response from CU-UP1 114-1, CU-CP processor 202 may cause CU-CP 112 to send another MC bearer context modification request to CU-UP2 114-2. CU-CP processor 202 may cause CU-CP 112 to send the other MC bearer context modification request based on E1AP. The other MC bearer context modification request may include the last delivered MRB progress received from CU-UP1. CU-CP processor 202 may then cause CU-CP 112 to receive another MC bearer context modification response in response to the other MC bearer context modification request, indicating successful reception of the last delivered MRB progress at CU-UP2.

[0081] Figure 6 The illustration shows a call flow 600 that facilitates the relocation of at least one MC session from CU-UP1 114-1 to CU-UP2 114-2 according to an example of this topic.

[0082] In call flow 600, at step 600-1, a session relocation indication may be sent from CU-UP1 114-1 to CU-CP 112. In one example, the session relocation indication may be sent to relocate at least one MC session from CU-UP1 114-1 to CU-UP2 114-2. The session relocation indication may include a first list of TNLAs, wherein the first list of TNLAs is associated with DUs 110-1 and 110-2 involved in at least one MC session.

[0083] In step 600-2, upon receiving a session relocation indication, CU-CP 112 may send an MC bearer context establishment request to CU-UP2 114-2, wherein the MC bearer context establishment request includes a first list of TNLAs.

[0084] In step 600-3, upon receiving an MC bearer context request, CU-UP2 can generate a second list of CU TNLAs, where each CU TNLA in the second list is associated with CU-UP2. Furthermore, each CU TNLA corresponds to a TNLA included in the first list of TNLAs. In step 600-4, after generating the second list of CU TNLAs, CU-UP2114-2 can send an MC bearer establishment response to CU-CP 112, where the MC bearer establishment response may include the second list of CU TNLAs.

[0085] In step 600-5, upon receiving an MC bearer establishment response from CU-UP2 114-2, CU-CP 112 may send a distribution modification request to 5GC 106. CU-CP 112 may send the distribution modification request to provide 5GC 106 with a second list of CU TNLAs to be used by 5GC 106 for data transfer to CU-UP2 114-2, wherein the CU TNLAs may be associated with CU-UP2 114-2. In step 600-6, CU-CP 112 may receive a distribution modification response in response to the distribution modification request.

[0086] In step 600-7, CU-CP 112 may send an MC distribution modification request to DU 110-1, wherein the MC distribution modification request includes a first list of TNLAs and a second list of CU TNLAs. In step 600-8, DU 110-1 may send an MC distribution modification response indicating successful reception of the MC distribution modification request. In one example, DU 110-1 may relocate at least one MC session from CU-UP1 114-1 to CU-UP2 114-2 based on the CU TNLA corresponding to the TNLA associated with DU 110-1.

[0087] In step 600-9, after at least one MC session has been relocated from CU-UP1 114-1 to CU-UP2 114-2, CU-CP 112 may send an MC bearer context modification request to CU-UP1 114-1. The MC bearer context modification request may be sent to provide CU-UP1 114-1 with a second list of CU TNLAs associated with CU-UP2, such that CU-UP1 114-1 may forward any data associated with at least one MC session from 5GC to CU-UP2 114-2. The MC bearer context modification request may also include a request for the progress of the last delivered MC radio bearer (MRB) associated with CU-UP1 114-1. In step 600-10, CU-CP 112 may receive an MC bearer context modification response including the progress of the last delivered MRB.

[0088] In step 600-11, upon receiving an MC bearer context modification response from CU-UP1 114-1, CU-CP 112 may send another MC bearer context modification request to CU-UP2 114-2. This other MC bearer context modification request may include the last delivered MRB progress received from CU-UP1. In step 600-12, CU-CP 112 may, in response to the other MC bearer context modification request, receive another MC bearer context modification response indicating successful reception of the last delivered MRB progress at CU-UP2.

[0089] Figure 7 and Figure 8 The illustrations illustrate methods 700 and 800, examples of those used in this topic, for relocating an MC session from CU-UP1 to CU-UP2. While methods 700 and 800 can be implemented to serve a variety of communication nodes, for ease of explanation, the current description of example methods 700 and 800 is provided with reference to the aforementioned CU-CP 112. The order of the various method blocks describing methods 700 and 800 should not be construed as limiting, and any number of the described method blocks can be combined in any order to implement methods 700 and 800 or alternative methods.

[0090] As will be readily understood, the blocks of methods 700 and 800 can be implemented by instructions stored in a non-transitory computer-readable medium. Non-transitory computer-readable media may include, for example, digital memory, magnetic storage media (such as disks and magnetic tapes), hard disk drives, or optically readable digital data storage media.

[0091] exist Figure 7 In block 702, an MC bearer context establishment request is sent to relocate at least one MC session from CU-UP1 to CU-UP2, wherein at least one MC session exists between CU-UP1 and one or more DUs. The bearer context establishment request includes a first list of CU TNLAs, wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs. In one example, the MC bearer context establishment request is sent to CU-UP2.

[0092] In one example, an MC bearer context establishment request is sent upon receiving a session relocation indication for relocating the MC session. In this example, the session relocation indication is received from CU-UP1.

[0093] In another example, the MC bearer context establishment request is sent based on a load indicator received from CU-UP1 114-1. In one example, the load indicator may indicate a count of one or more MC sessions existing between CU-UP1 114-1 and multiple DUs 110-1 and 110-2, where the one or more sessions may include at least one MC session. If it is determined that the count of one or more MC sessions is greater than a threshold, a transmission for relocating the bearer context establishment request for at least one MC session is triggered. In another example, the load indicator may indicate the MC data traffic volume of at least one MC session. If it is determined that the MC data traffic volume exceeds a threshold, a transmission for relocating the bearer context establishment request for at least one MC session is triggered.

[0094] At box 704, an MC bearer context establishment response is received from CU-UP2. The MC bearer context establishment response is received as a response to an MC bearer context establishment request. In one example, the MC bearer context establishment response includes a second list of CU TNLAs, where each CU TNLA in the second list of CU TNLAs is associated with CU-UP2. Furthermore, each CU TNLA corresponds to a TNLA included in a first list of TNLAs.

[0095] At box 706, a second list of CU TNLAs is sent to one or more DUs. In one example, a DU can use the second list of TNLAs to relocate at least one MC session to CU-UP2.

[0096] exist Figure 8 In block 802, an MC bearer context establishment request is sent to relocate at least one MC session from CU-UP1 to CU-UP2. In one example, the MC bearer context establishment request can be sent to CU-UP2.

[0097] At box 804, an MC bearer context modification request is sent to CU-UP2, wherein the MC bearer context modification request includes a first list of TNLAs. In one example, each TNLA in the first list of TNLAs is associated with a DU in one or more DUs.

[0098] At box 806, an MC bearer context modification response is received in response to an MC bearer context modification request. In one example, the MC bearer context modification response includes a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs.

[0099] At box 808, a second list of CU TNLAs is sent to one or more DUs. In one example, one or more DUs may use the second list of CU TNLAs to relocate at least one MC session to CU-UP2.

[0100] Figure 9 and Figure 10The illustrations depict methods 900 and 1000, according to another example of this topic, for relocating an MC session from CU-UP1 to CU-UP2. While methods 900 and 1000 can be implemented to serve various communication nodes, for ease of explanation, the current description of example methods 900 and 1000 is provided with reference to CU-UP2 114-2 above. The order of the various method blocks describing methods 900 and 1000 should not be construed as limiting, and any number of described method blocks can be combined in any order to implement methods 900 and 1000 or alternative methods.

[0101] As will be readily understood, the blocks of methods 900 and 1000 can be implemented by instructions stored in a non-transitory computer-readable medium. Non-transitory computer-readable media may include, for example, digital memory, magnetic storage media (such as disks and magnetic tapes), hard disk drives, or optically readable digital data storage media.

[0102] exist Figure 9 In block 902, an MC bearer context establishment request is received. This request is used to relocate at least one MC session from CU-UP1 to CU-UP2. At least one MC session exists between CU-UP1 and one or more DUs. The MC bearer context establishment request is received from CU-CP. Furthermore, the MC bearer context establishment request includes a first list of TNLAs, where each TNLA in the first list is associated with a DU in one or more DUs.

[0103] At box 904, a second list of CU TNLAs is generated, wherein each CU TNLA in the second list of CU TNLAs is associated with CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs. In one example, the second list of CU TNLAs is used to relocate at least one MC session to CU-UP2.

[0104] At box 906, the MC bearer context response is sent to the CU-CP. The MC bearer context response is sent in response to the MC bearer context request. Additionally, the MC bearer context response includes a second list of CU TNLAs.

[0105] exist Figure 10 In block 1002, an MC bearer context establishment request for relocating at least one MC session from CU-UP1 to CU-UP2 is received. In one example, the MC bearer context establishment request can be received from CU-CP.

[0106] At box 1004, an MC bearer context modification request, including a first list of TNLAs, can be received, where each TNLA in the first list is associated with a DU in one or more DUs. In one example, the MC bearer context modification request is received from the CU-CP.

[0107] At box 1006, a second list of CU TNLAs is generated, where each CU TNLA in the second list of CU TNLAs is associated with CU-UP2. Furthermore, each CU TNLA corresponds to a TNLA included in the first list of TNLAs. In one example, the second list of CU TNLAs is used to relocate at least one MC session to CU-UP2.

[0108] At box 1008, an MC bearer context modification response is sent to the CU-CP. The MC bearer context modification response is sent in response to a bearer context modification request. In one example, the MC bearer context modification response includes a second list of CU TNLAs.

[0109] Figure 11 The illustration shows method 1100 for relocating an MC session from CU-UP1 to CU-UP2 according to another example of this topic. While method 1100 can be implemented to serve various communication nodes, for ease of explanation, the current description of example method 1100 is provided with reference to DU 110-1 above. The order of the various method blocks describing method 1100 should not be construed as limiting, and any number of described method blocks can be combined in any order to implement method 1100 or alternative methods.

[0110] As will be readily understood, the block of method 1100 can be implemented by instructions stored in a non-transitory computer-readable medium. A non-transitory computer-readable medium may include, for example, digital memory, magnetic storage media (such as disks and tapes), hard disk drives, or optically readable digital data storage media.

[0111] At box 1102, an MC distribution modification request is received for relocating at least one multicast (MC) session from CU-UP1 to CU-UP2, wherein at least one MC session exists between CU-UP1 and DU. The MC distribution modification request includes a first list of TNLAs and a second list of CU TNLAs, wherein the first list of TNLAs includes one of a DU TNLA associated with DU and a CU TNLA associated with CU-UP1, and the second list of CU TNLAs is associated with CU-UP2. The second list of CU TNLAs includes CU TNLAs corresponding to the CU TNLAs, wherein the CU TNLAs can be used to relocate at least one MC session to CU-UP2.

[0112] At box 1104, at least one MC session is relocated to CU-UP2 based on the second list of CU TNLA.

[0113] This subject matter presents various techniques for relocating at least one MC session from CU-CP1 to CU-CP2. These and other aspects are also described in the context of the following embodiments:

[0114] A method implemented by a centralized unit control plane (CU-CP), the method comprising: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs. In response to the MC bearer context establishment request, an MC bearer context establishment response is received from the CU-UP2, the MC bearer context establishment response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in a first list of TNLAs; and Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

[0115] A method implemented by a centralized unit control plane (CU-CP), the method comprising: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). Send an MC bearer context modification request to the CU-UP2, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; and In response to the MC bearer context modification request, an MC bearer context modification response is received from the CU-UP2, the MC bearer context modification response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in a first list of TNLAs; and Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

[0116] As described in the above embodiments, the MC bearer context establishment request is sent upon receiving a session relocation indication for relocating the at least one MC session.

[0117] The method described in the above embodiments further includes: Receive a load indicator from the CU-UP1, the load indicator indicating the MC resource utilization of one or more MC sessions existing between the CU-UP1 and a plurality of DUs, the one or more MC sessions including the at least one MC session; and If the MC resource utilization rate is determined to exceed a threshold, the transmission of the MC bearer context establishment request to the CU-UP2 is triggered to relocate the at least one MC session.

[0118] The method described in the above embodiments further includes: Send an MC bearer context modification request to CU-UP1, including a second list of CU TNLAs associated with CU-UP2; and The MC bearer context modification response is received from the CU-UP1 in response to the MC bearer context modification request.

[0119] The method described in the above embodiments further includes: Send an NG application protocol MC distribution modification request, which includes the second list of the CU TNLA, to the fifth generation core (5GC).

[0120] A method implemented by a first user plane (CU-UP1) of a centralized unit, the method comprising: Monitor the MC resource utilization associated with one or more MC sessions between the CU-UP1 and multiple distributed units (DUs); and If it is determined that the MC resource utilization exceeds a threshold, a session relocation indication is sent to relocate at least one MC session from the one or more sessions.

[0121] A method implemented by a second user plane (CU-UP2) of a centralized unit, the method comprising: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The MC bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs. A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context establishment request, an MC bearer context establishment response including a second list of CU TNLAs is sent to the CU-CP.

[0122] A method implemented by a second user plane (CU-UP2) of a centralized unit, the method comprising: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The CU-CP receives an MC bearer context modification request, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context modification request, an MC bearer context modification response including a second list of CU TNLAs is sent to the CU-CP.

[0123] A method implemented by a distributed unit (DU), the method comprising: A multicast (MC) distribution modification request is received, the MC distribution modification request being used to relocate at least one MC session from a first user plane (CU-UP1) of a centralized unit to a second user plane (CU-UP2), the at least one MC session existing between CU-UP1 and the DU, the MC distribution modification request including a first list of transport network layer addresses (TNLAs) and a second list of CU TNLAs, the first list of TNLAs including one of a TNLA associated with the DU and a CU TNLA associated with CU-UP1, the second list of CU TNLAs being associated with CU-UP2, the second list of CU TNLAs including CU TNLAs corresponding to the TNLAs in the first list of TNLAs, and the second list of CU TNLAs being usable for relocating the at least one MC session to CU-UP2; and The at least one MC session is relocated to the CU-UP2 based on the second list of the CU TNLA.

[0124] A centralized unit control plane (CU-CP), the CU-CP comprising: At least one CU-CP processor; A computer-readable medium, including instructions that, when executed by the at least one CU-CP processor, cause the CU-CP to: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list is associated with a DU in the one or more DUs. In response to the MC bearer context establishment request, an MC bearer context establishment response is received from the CU-UP2, the MC bearer context establishment response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in a first list of TNLAs; and Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

[0125] A centralized unit control plane (CU-CP), the CU-CP comprising: At least one CU-CP processor; A computer-readable medium, including instructions that, when executed by the at least one CU-CP processor, cause the CU-CP to: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to CU-UP2, the at least one MC session existing between CU-UP1 and one or more distributed units (DUs); and Send an MC bearer context modification request to the CU-UP2, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; and In response to the MC bearer context modification request, an MC bearer context modification response is received from the CU-UP2, the MC bearer context modification response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in a first list of TNLAs; and Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

[0126] As described in the above embodiments, the at least one CU-CP processor is configured to cause the CU-CP to send the MC bearer context establishment request when it receives a session relocation indication for relocating the at least one MC session.

[0127] As described in the above embodiments, the at least one CU-CP processor enables the CU-CP to: Receive a load indicator from the CU-UP1, the load indicator indicating the multicast resource utilization of one or more MC sessions existing between the CU-UP1 and a plurality of DUs, the one or more sessions including the at least one MC session; and If it is determined that the multicast resource utilization exceeds a threshold, the transmission of the bearer context establishment request to the CU-UP2 is triggered to relocate the at least one MC session.

[0128] As described in the above embodiments, the at least one CU-CP processor further enables the CU-CP to: Send an MC bearer context modification request to CU-UP1, including a second list of CU TNLAs associated with CU-UP2; and The MC bearer context modification response is received from the CU-UP1 in response to the MC bearer context modification request.

[0129] As described in the above embodiments, the at least one CU-CP processor causes the CU-CP to send an NG application protocol MC distribution modification request to the fifth-generation core (5GC) including a second list of CU TNLAs.

[0130] A first user plane (CU-UP1) of a centralized unit, the CU-UP1 comprising: At least one CU-UP1 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP1 processor, cause the CU-UP1 to: Monitor the MC resource utilization associated with one or more MC sessions between the CU-UP1 and multiple distributed units (DUs); and If it is determined that the MC resource utilization exceeds a threshold, a session relocation indication is sent to relocate at least one MC session from the one or more sessions.

[0131] A second user plane (CU-UP2) of a centralized unit, the CU-UP2 comprising: At least one CU-UP2 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP2 processor, cause the CU-UP2 to: The control plane (CU-CP) of the centralized unit receives an MC bearer context establishment request for relocating at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2, the at least one MC session existing between the CU-UP1 and one or more distributed units (DUs), and the MC bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context establishment request, an MC bearer context establishment response including a second list of CU TNLAs is sent to the CU-CP.

[0132] A second user plane (CU-UP2) of a centralized unit, the CU-UP2 comprising: At least one CU-UP2 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP2 processor, cause the CU-UP2 to: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The CU-CP receives an MC bearer context modification request, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context modification request, an MC bearer context modification response including a second list of CU TNLAs is sent to the CU-CP.

[0133] A distributed unit (DU) includes: At least one DU processor; A computer-readable medium, including instructions that, when executed by the at least one DU processor, cause the DU to: A request to modify the distribution of an MC (Multi-User Center) is received. This request is used to relocate at least one MC session from a first user plane (CU-UP1) of a centralized unit to a second user plane (CU-UP2). The at least one MC session exists between CU-UP1 and the DU (Multi-User Center). The MC distribution modification request includes a first list of Transport Network Layer Addresses (TNLAs) and a second list of CUTNLAs. The first list of TNLAs includes DU TNLAs associated with the DU or CU TNLAs associated with CU-UP1. The second list of CU TNLAs is associated with CU-UP2 and includes CU TNLAs corresponding to TNLAs in the first list of TNLAs. The second list of CU TNLAs can be used to relocate the at least one MC session to CU-UP2. The at least one MC session is relocated to the CU-UP2 based on the second list of the CU TNLA.

[0134] Although examples of this subject matter have been described in language specific to methods and / or structural features, it should be understood that this subject matter is not limited to the specific methods or features described. Rather, these methods and specific features are disclosed and interpreted as examples of this subject matter.

Claims

1. A method implemented by a centralized unit control plane (CU-CP), the method comprising: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs. In response to the MC bearer context establishment request, an MC bearer context establishment response is received from the CU-UP2, the MC bearer context establishment response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs; as well as Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

2. A method implemented by a centralized unit control plane (CU-CP), the method comprising: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). Send an MC bearer context modification request to the CU-UP2, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; as well as In response to the MC bearer context modification request, an MC bearer context modification response is received from the CU-UP2, the MC bearer context modification response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs; as well as Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

3. The method according to claim 1 or 2, wherein the MC bearer context establishment request is sent upon receiving a session relocation indication for relocating the at least one MC session.

4. The method according to claim 1 or 2, further comprising: Receive a load indicator from the CU-UP1, the load indicator indicating the MC resource utilization of one or more MC sessions existing between the CU-UP1 and a plurality of DUs, the one or more MC sessions including the at least one MC session; as well as If the MC resource utilization rate is determined to exceed a threshold, the transmission of the MC bearer context establishment request to the CU-UP2 is triggered to relocate the at least one MC session.

5. The method according to claim 1 or 2, further comprising: Send an MC bearer context modification request to the CU-UP1, including a second list of CU TNLAs associated with the CU-UP2; as well as The MC bearer context modification response is received from the CU-UP1 in response to the MC bearer context modification request.

6. The method according to any one of claims 1 to 5, further comprising: Send an NG application protocol MC distribution modification request, which includes the second list of the CU TNLA, to the fifth generation core (5GC).

7. A method implemented by a first user plane (CU-UP1) of a centralized unit, the method comprising: Monitor the MC resource utilization associated with one or more MC sessions existing between the CU-UP1 and multiple distributed units (DUs); as well as If it is determined that the MC resource utilization exceeds a threshold, a session relocation indication is sent to relocate at least one MC session from the one or more sessions.

8. A method implemented by a second user plane (CU-UP2) of a centralized unit, the method comprising: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The MC bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs. A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context establishment request, an MC bearer context establishment response including a second list of CU TNLAs is sent to the CU-CP.

9. A method implemented by a second user plane (CU-UP2) of a centralized unit, the method comprising: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The CU-CP receives an MC bearer context modification request, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context modification request, an MC bearer context modification response including a second list of CU TNLAs is sent to the CU-CP.

10. A method implemented by a distributed unit (DU), the method comprising: A multicast (MC) distribution modification request is received, the MC distribution modification request being used to relocate at least one MC session from a first user plane (CU-UP1) of a centralized unit to a second user plane (CU-UP2), the at least one MC session existing between CU-UP1 and the DU, the MC distribution modification request including a first list of transport network layer addresses (TNLAs) and a second list of CU TNLAs, the first list of TNLAs including one of a TNLA associated with the DU and a CU TNLA associated with CU-UP1, the second list of CU TNLAs being associated with CU-UP2, the second list of CU TNLAs including CU TNLAs corresponding to the TNLAs in the first list of TNLAs, and the second list of CU TNLAs being usable for relocating the at least one MC session to CU-UP2; and The at least one MC session is relocated to the CU-UP2 based on the second list of the CU TNLA.

11. A centralized unit control plane (CU-CP), the CU-CP comprising: At least one CU-CP processor; A computer-readable medium, including instructions that, when executed by the at least one CU-CP processor, cause the CU-CP to: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs. as well as In response to the MC bearer context establishment request, an MC bearer context establishment response is received from the CU-UP2, the MC bearer context establishment response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs; as well as Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

12. A centralized unit control plane (CU-CP), the CU-CP comprising: At least one CU-CP processor; A computer-readable medium, including instructions that, when executed by the at least one CU-CP processor, cause the CU-CP to: A multicast (MC) bearer context establishment request is sent to the second user plane (CU-UP2) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). as well as Send an MC bearer context modification request to the CU-UP2, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; as well as In response to the MC bearer context modification request, an MC bearer context modification response is received from the CU-UP2, the MC bearer context modification response including a second list of CU TNLAs, wherein each CU TNLA in the second list of CU TNLAs is associated with the CU-UP2, and each CU TNLA corresponds to a TNLA included in the first list of TNLAs; as well as Send a second list of the CU TNLA to the one or more DUs for relocating the at least one MC session to the CU-UP2.

13. The CU-CP according to claim 11 or 12, wherein the at least one CU-CP processor is configured to cause the CU-CP to send the MC bearer context establishment request upon receiving a session relocation indication for relocating the at least one MC session.

14. The CU-CP according to claim 11 or 12, wherein the at least one CU-CP processor causes the CU-CP to: Receive a load indicator from the CU-UP1, the load indicator indicating the multicast resource utilization of one or more MC sessions existing between the CU-UP1 and a plurality of DUs, the one or more sessions including the at least one MC session; and If it is determined that the multicast resource utilization exceeds a threshold, the transmission of the bearer context establishment request to the CU-UP2 is triggered to relocate the at least one MC session.

15. The CU-CP according to any one of claims 11 to 14, wherein the at least one CU-CP processor causes the CU-CP to further: Send an MC bearer context modification request to CU-UP1, including a second list of CU TNLAs associated with CU-UP2; and The MC bearer context modification response is received from the CU-UP1 in response to the MC bearer context modification request.

16. The CU-CP according to any one of claims 11 to 15, wherein the at least one CU-CP processor causes the CU-CP to send an NG application protocol MC distribution modification request to the fifth-generation core (5GC) including a second list of the CU TNLA.

17. A first user plane (CU-UP1) of a centralized unit, the CU-UP1 comprising: At least one CU-UP1 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP1 processor, cause the CU-UP1 to: Monitor MC resource utilization associated with one or more MC sessions existing between the CU-UP1 and multiple distributed units (DUs); and If it is determined that the MC resource utilization exceeds a threshold, a session relocation indication is sent to relocate at least one MC session from the one or more sessions.

18. A second user plane (CU-UP2) of a centralized unit, said CU-UP2 comprising: At least one CU-UP2 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP2 processor, cause the CU-UP2 to: The control plane (CU-CP) of the centralized unit receives an MC bearer context establishment request for relocating at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2, the at least one MC session existing between the CU-UP1 and one or more distributed units (DUs), and the MC bearer context establishment request includes a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in the one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context establishment request, an MC bearer context establishment response including a second list of CU TNLAs is sent to the CU-CP.

19. A second user plane (CU-UP2) of a centralized unit, said CU-UP2 comprising: At least one CU-UP2 processor; A computer-readable medium, including instructions that, when executed by the at least one CU-UP2 processor, cause the CU-UP2 to: A multicast (MC) bearer context establishment request is received from the control plane (CU-CP) of the centralized unit. The MC bearer context establishment request is used to relocate at least one MC session from the first user plane (CU-UP1) of the centralized unit to the CU-UP2. The at least one MC session exists between the CU-UP1 and one or more distributed units (DUs). The CU-CP receives an MC bearer context modification request, the MC bearer context modification request including a first list of transport network layer addresses (TNLAs), wherein each TNLA in the first list of TNLAs is associated with a DU in one or more DUs; A second list of CU TNLAs is generated, each CU TNLA in the second list being associated with the CU-UP2, each CU TNLA corresponding to a TNLA included in the first list of TNLAs, and the second list of CU TNLAs is used to relocate the at least one MC session to the CU-UP2; and In response to the bearer context modification request, an MC bearer context modification response including a second list of CU TNLAs is sent to the CU-CP.

20. A distributed unit (DU), comprising: At least one DU processor; A computer-readable medium, including instructions that, when executed by the at least one DU processor, cause the DU to: A request to modify the distribution of an MC (Multi-User Center) is received. This request is used to relocate at least one MC session from a first user plane (CU-UP1) of a centralized unit to a second user plane (CU-UP2). The at least one MC session exists between CU-UP1 and the DU (Multi-User Center). The MC distribution modification request includes a first list of Transport Network Layer Addresses (TNLAs) and a second list of CUTNLAs. The first list of TNLAs includes DU TNLAs associated with the DU or CU TNLAs associated with CU-UP1. The second list of CU TNLAs is associated with CU-UP2 and includes CU TNLAs corresponding to TNLAs in the first list of TNLAs. The second list of CU TNLAs can be used to relocate the at least one MC session to CU-UP2. The at least one MC session is relocated to the CU-UP2 based on the second list of the CU TNLA.

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