Distributed central unit control plane resilience with optimized resource allocation

Abstract

Various example embodiments relate to devices, methods, apparatus, and computer readable media for distributed central unit control plane (CU-CP) resilience with optimized resource allocation in a split radio access network (RAN) architecture. A first CU-CP node in the radio access network may be configured to send a capacity polling request to one or more second CU-CP nodes in the radio access network configured as backup CU-CP nodes for the first CU-CP node; receiving a capacity polling response from the one or more second CU-CP nodes, wherein the capacity polling response comprises capacity information of the one or more second CU-CP nodes; and allocating at least one distributed unit associated with the first CU-CP node to one of the one or more second CU-CP nodes at least based on the capacity information of the one or more second CU-CP nodes.

Description

Technical Field

[0001] Various example embodiments described herein relate generally to communication techniques, and more particularly to devices, methods, apparatus, and computer-readable media for distributed central unit control plane (CU-CP) resiliency with optimized resource allocation in a split radio access network (RAN) architecture. Background Art

[0002] Certain abbreviations that may be found in the specification and / or drawings are defined herein as follows:

[0003] Network resilience refers to the ability of a network to provide an acceptable level of service to users regardless of any failures or outages. In a radio access network (RAN) (e.g., next-generation radio access network (NG-RAN)), active base stations (e.g., next-generation Node Bs (gNBs)) may be configured with standby gNBs to ensure network resilience. When an active gNB goes out of service due to, for example, planned downtime, interference, attacks, or natural disasters, the standby gNB may be activated to provide services to users in place of the out-of-service gNB. Summary of the invention

[0004] The following provides a brief summary of example embodiments to provide a basic understanding of some aspects of various embodiments. It should be noted that this summary is not intended to identify key features of essential elements or define the scope of the embodiments, and its sole purpose is to introduce some concepts in a simplified form as a prelude to the more detailed description provided below.

[0005] In a first aspect, an example embodiment of a first central unit control plane (CU-CP) node in a radio access network is provided. The first CU-CP node may include at least one processor and at least one memory, the at least one memory storing instructions. The instructions, when executed by at least one processor, cause the first CU-CP node to at least send a capacity polling request to one or more second CU-CP nodes in the radio access network that are configured as backup CU-CP nodes for the first CU-CP node; receive a capacity polling response from the one or more second CU-CP nodes, the capacity polling response including capacity information of the one or more second CU-CP nodes; and allocate at least one distributed unit associated with the first CU-CP node to one of the one or more second CU-CP nodes based at least on the capacity information of the one or more second CU-CP nodes.

[0006] In a second aspect, an example embodiment of a second central unit control plane (CU-CP) node in a radio access network is provided. The second CU-CP node may include at least one processor and at least one memory, the at least one memory storing instructions. The instructions, when executed by at least one processor, cause the second CU-CP node to at least receive a capacity polling request from one or more first CU-CP nodes in the radio access network; and in response to the received capacity polling request, send a capacity polling response to one or more first CU-CP nodes, the second CU-CP node being configured as a backup CU-CP node for one or more first CU-CP nodes, and the capacity polling response may include capacity information of the second CU-CP node.

[0007] Example embodiments of methods, apparatus, and computer program products are also provided. Such example embodiments generally correspond to the example embodiments described above, and for convenience, repeated descriptions thereof are omitted here.

[0008] Other features and advantages of example embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of example embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Some example embodiments will now be described, by way of non-limiting examples, with reference to the accompanying drawings.

[0010] Figure 1 is a schematic block diagram showing a split architecture of a next generation Node B (gNB).

[0011] Figure 2 is a schematic block diagram illustrating an example deployment and configuration of multiple gNB central unit control planes (gNB-CU-CP) according to an example embodiment of the present disclosure.

[0012] Figure 3 is a schematic message sequence chart illustrating a process according to an example embodiment of the present disclosure.

[0013] Figure 4 is a schematic flow chart illustrating a method according to an example embodiment of the present disclosure.

[0014] Figure 5 is a schematic flow chart illustrating a method according to an example embodiment of the present disclosure.

[0015] Figure 6 is a schematic block diagram illustrating an apparatus according to an example embodiment of the present disclosure.

[0016] Figure 7is a schematic block diagram illustrating an apparatus according to an example embodiment of the present disclosure.

[0017] Figure 8 is a schematic block diagram illustrating a device according to an example embodiment of the present disclosure.

[0018] Throughout the drawings, the same or similar reference numerals indicate the same or similar elements, and repeated description of the same elements will be omitted. DETAILED DESCRIPTION

[0019] Hereinafter, some example embodiments are described in detail with reference to the accompanying drawings. For the purpose of providing a thorough understanding of various concepts, the following description includes specific details. However, it is apparent to those skilled in the art that these concepts can be practiced without these specific details. In some cases, well-known circuits, techniques, and components are shown in block diagram form to avoid obscuring the concepts and features described.

[0020] In the next generation radio access network (NG-RAN), a split architecture has been introduced to divide a base station (e.g., next generation Node B (gNB)) into a central unit (CU) and a distributed unit (DU). In order to realize the concept of cloud RAN, the CU can also be divided into a CU control plane (CP) and a CU user plane (UP).

[0021] Figure 1 1 shows a split architecture of a gNB 110 in which some example embodiments of the present disclosure may be implemented. Figure 1 As shown, the gNB 110 may include a CU-CP 112, one or more CU-UPs 114, and one or more DUs 116 (two DUs 116a, 116b are shown as examples). The CU-CP 112 hosts the control plane portion of the Radio Resource Control (RRC) protocol and the Packet Data Convergence Protocol (PDCP), the CU-UP 114 hosts the user plane portion of the PDCP protocol and the Service Data Adaptation Protocol (SDAP), and the DU 116 hosts the Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers. The CU-CP 112 is connected to the CU-UP 114 via an E1 interface and to the DU 116 via an F1-C interface. The DU 116 is connected to the CU-UP 114 via an F1-U interface. One DU 116 is connected to only one CU-CP 112, and one CU-UP 114 is connected to only one CU-CP 112. One DU 116 may be connected to a plurality of CU-UPs 114 under the control of the same CU-CP 112 , and one CU-UP 114 may be connected to a plurality of DUs 116 under the control of the same CU-CP 112 .

[0022] In a split architecture, NG-RAN functional nodes can be optimally deployed in different locations based on use cases and performance requirements. In one example, CU-CP 112 can be located near DU 116 to achieve low latency for CP processes such as RRC connection establishment and switching. On the other hand, CU-UP 114 can be concentrated in, for example, an operator data center, which is beneficial for cloud implementations and can provide a centralized termination point for UP traffic in dual-connectivity and tightly coupled scenarios. In addition, additional CU-UP 114 can be deployed near DU 116 to provide low latency for ultra-reliable low-latency communication (URLLC) applications.

[0023] It should be understood that gNB 110 is shown as an example and the split architecture may also be applied to other base stations, such as an evolved Node B (eNB), a next generation eNB (ng-e NB), a super 5G base station, a 6G base station, or a future base station.

[0024] Because the CU-CP 112 controls multiple DUs 116 and each DU 116 serves one or more cells, the resilience of the CU-CP 112 is critical to providing service continuity and avoiding unexpected outages. If the CU-CP 112 fails, it will take a long time to establish a new F1 interface from scratch, which will result in a large number of UE releases and a large amount of downtime before the communication system is restored. The 3GPP specification does not exclude the scheme in which DUs 116 and / or CU-UPs 114 are connected to more than one CU-CP 112 for resilience, but this scheme violates the current cardinality rules for the RAN architecture and will cause other problems. For example, radio resource management (RRM) performed by multiple CU-CPs 112 will cause segmentation of resources and new coordination overhead between CU-CPs.

[0025] Another option is to deploy a standby CU-CP for geographic redundancy resiliency of CU-CP 112. When CU-CP 112 encounters a failure, the standby CU-CP can be activated and take over the role of CU-CP 112. However, in many cases, a single, fixed, and static standby CU-CP may be a limitation. For example, a disaster that affects the active CU-CP 112 may also affect the standby CU-CP. In addition, there may be performance issues (e.g., delays) when the standby CU-CP is operated to completely replace the active CU-CP 112. This limitation can be alleviated to a certain extent by deploying multiple standby CU-CP nodes for the active CU-CP 112, but such deployment is severely constrained by the available number of CU-CP nodes in the network for service.

[0026] Some example embodiments of the present disclosure propose flexible configuration of multiple standby CU-CPs for a given active CU-CP, while optimizing resource allocation during switching from the active CU-CP to one or more of the configured multiple standby CU-CPs. Typically, an active CU-CP can be configured with multiple standby CU-CPs, and the active CU-CP can also be configured with standby CU-CPs for multiple active CU-CPs. Such a configuration can increase the number of configurable standby CU-CPs for a given active CU-CP, thereby reducing the risk that both the active CU-CP and a single standby CU-CP are affected by disasters without the need to deploy more dedicated standby CU-CPs in the network, because the active CU-CP can also be configured as a standby node for other active CU-CPs. In some example embodiments, the active CU-CP can periodically receive capacity information from multiple configured standby CU-CPs. The active CU-CP can dynamically allocate the DU connected to the active CU-CP to one or more of the configured standby CU-CPs based on the received capacity information and optional other factors (such as the geographic location of the standby CU-CP). In the event of an active CU-CP failure, when the user switches from the active CU-CP to the standby CU-CP, resource allocation can be optimized and load balancing between CU-CPs can be achieved, thereby improving user experience.

[0027] Figure 2 is a schematic block diagram illustrating an example deployment and configuration of multiple gNB central unit control planes (gNB-CU-CP) according to an example embodiment of the present disclosure. Figure 2 As shown, four gNB-CU-CPs 112, 122, 132, 142 are shown as examples, and dashed arrows are used to indicate the standby node configuration between the four gNB-CU-CPs. The four gNB-CU-CPs 112, 122, 132, and 142 may all be active nodes in their respective base stations, i.e., they each control one or more DUs to serve one or more cells. The network operator may configure one or more standby nodes for a given active gNB-CU-CP. In this example, the first gNB-CU-CP 112 is configured with two standby nodes, i.e., the second gNB-CU-CP 122 and the third gNB-CU-CP 132. The second gNB-CU-CP 122 is configured with the fourth gNB-CU-CP 144 as a standby node, and the third gNB-CU-CP 132 is configured with the second gNB-CU-CP 122 as a standby node. The fourth gNB-CU-CP 144 is not configured with any standby node. It should be understood that the multiple backup nodes configured for a given active gNB-CU-CP may be from different geographic redundancy areas / locations. Figure 2The standby configurations shown are also summarized in Table 1 below. It can be seen that many gNB-CU-CPs are configured with one or more standby nodes, while the number of gNB-CU-CPs deployed in the network does not increase (i.e., no nodes dedicated to standby are deployed). Table 1

[0028] Figure 3 A process 200 according to an example embodiment of the present disclosure is shown. The process 200 may be performed at an active gNB-CU-CP, one or more DUs connected to the active gNB-CU-CP, and one or more standby nodes configured for the active gNB-CU-CP, e.g., at Figure 2 At the active gNB-CU-CP 112 shown in the figure, DUs 116a and 116b connected to the active gNB-CU-CP 112, and standby gNB-CU-CPs 122 and 132 configured for the active gNB-CU-CP 112. The active and standby gNB-CU-CPs and DUs may each include multiple parts, modules, components, or elements for performing the operations in process 200. The parts, modules, components, or elements may be implemented in various ways, including but not limited to software, hardware, firmware, or any combination thereof. Figure 3 In the process 200 shown in FIG. 2 , operations represented by dashed lines may be optionally or selectively performed in some example embodiments, or may be omitted in other example embodiments.

[0029] like Figure 3As shown, once the active gNB-CU-CP 112 is configured with the standby gNB-CU-CPs 122 and 132, the active gNB-CU-CP 112 may poll the standby gNB-CU-CPs 122, 132 for capacity availability at 210. For example, the active gNB-CU-CP 112 may send a capacity polling request to the standby gNB-CU-CP 122 at 210a and send a capacity polling request to the standby gNB-CU-CP 132 at 210b. In an example, the capacity polling request may include a standby capacity requirement of the active gNB-CU-CP 112. The standby capacity requirement may indicate all cells served by the active gNB-CU-CP 112 or a plurality of cells served by respective DUs (i.e., DUs 116a, 116b) connected to the active gNB-CU-CP 112. Alternatively or additionally, the spare capacity requirement may indicate a number of user equipments (UEs) connected to the active gNB-CU-CP 112. The standby gNB-CU-CP 122, 132 may know from the spare capacity requirement how much resources the active gNB-CU-CP 112 needs to distribute the DUs associated with the active gNB-CU-CP 112 (and the users served by the DUs) in case of a failure.

[0030] In an example, the standby polling request may be triggered by a predetermined event. For example, if the active gNB-CU-CP 112 detects the possibility of a particular fault by running an internal fault detection algorithm, or receives a fault indication from another network node or function (e.g., an operations administration and maintenance (OAM) function, a RAN data analysis function (DAF), or a core network data analysis function (DAF)), the active gNB-CU-CP 112 may send a capacity polling request to the standby gNB-CU-CP 122, 132. The capacity polling request may also be sent before a planned downtime (e.g., for routine maintenance or software / hardware upgrades).

[0031] In another example, the standby polling request may be periodically sent to the standby gNB-CU-CP 122, 132, or the standby polling request may include a periodic indication instructing the standby gNB-CU-CP 122, 132 to periodically respond to the standby polling request.

[0032] It should be understood that the standby gNB-CU-CPs 122, 132 may each be configured as a standby node for more than one active gNB-CU-CP, and thus the standby gNB-CU-CPs 122, 132 may receive standby polling requests from more than one active gNB-CU-CP at different times. Figure 3The operations between the standby gNB-CU-CPs 122, 132 and the active gNB-CU-CP 112 shown in FIG. 1 also apply to the operations between any one of the standby gNB-CU-CPs 122, 132 and the active gNB-CU-CP(s) associated therewith.

[0033] In response to the capacity poll request, the standby gNB-CU-CP 122, 132 may send a capacity poll response at 212a, 212b, respectively, to the active gNB-CU-CP 112. The capacity poll response may include capacity information of the respective standby gNB-CU-CP 122, 132, which will be described in detail below. As described above, the capacity poll response may be sent to the active gNB-CU-CP 112 periodically.

[0034] In an example, the capacity information may indicate resources currently being used at the corresponding standby gNB-CU-CP 122, 132. As described above, the standby gNB-CU-CP 122, 132 may also operate as an active node of a different base station itself. The resources currently being used may include, for example, a plurality of cells (and cell IDs) currently supported at the standby gNB-CU-CP, a plurality of UE RRCs currently connected to the standby gNB-CU-CP, a slice currently served by the standby gNB-CU-CP, a tracking area identifier (TAI) currently configured for the standby gNB-CU-CP, and the like. Based on the resources currently being used, the active gNB-CU-CP 112 may estimate the available resources / capacity at the standby gNB-CU-CP.

[0035] In another example, the capacity information included in the capacity poll response may indicate available resources that the standby gNB-CU-CP 122, 132 may reserve for the active gNB-CU-CP 112. For example, the capacity information may indicate resources corresponding to a hardware card equipped in the standby gNB-CU-CP for spare capacity purposes, or a plurality of cells, UEs, slices, and / or TAIs that the standby gNB-CU-CP may additionally support.

[0036] It should be understood that when the capacity information includes resources currently used at the standby gNB-CU-CP 122, 132 or idle resources at the standby gNB-CU-CP 122, 132, the capacity information received in the new capacity poll response may overwrite the capacity information received in the previous capacity poll response.

[0037] In yet another example, the capacity information included in the capacity poll response may indicate a change (amount of change) in resources currently being used at the standby gNB-CU-CP or a change (amount of change) in idle resources available at the standby gNB-CU-CP. For example, when the standby gNB-CU-CP 122, 132 is configured as a standby node for the active gNB-CU-CP 112, before reporting a change in the used resources or idle resources to the active gNB-CU-CP 112, the standby gNB-CU-CP 122, 132 may report an initial amount of used resources or idle resources to the active gNB-CU-CP 112. In the case where the capacity poll response is periodically sent to the active gNB-CU-CP 112, the standby gNB-CU-CP 122, 132 may report an initial amount of used resources or idle resources before or in a first capacity poll response, and then report a change in used resources or idle resources in a subsequent capacity poll response. The change in used resources or idle resources may include an amount of increase or decrease in currently used resources or idle resources relative to the used resources or idle resources associated with the initial report or the previous report. The active gNB-CU-CP 112 may then obtain the currently used resources or idle resources by accumulating the initial amount of used resources or idle resources and the latest change amount of used resources or idle resources, or by accumulating the initial amount and all received change amounts.

[0038] It should be understood that when the standby gNB-CU-CP 122 or 132 is configured as a standby node for multiple active gNB-CU-CPs, the gNB-CU-CP 122 or 132 may report capacity information to all active gNB-CU-CPs of the multiple active gNB-CU-CPs that initiate polling, but ultimately the standby gNB-CU-CP 122 or 132 may be activated for one active gNB-CU-CP among the multiple active gNB-CU-CPs.

[0039] At 214, the active gNB-CU-CP 112 may allocate the DUs 116a, 116b connected to the active gNB-CU-CP 112 to the standby gNB-CU-CPs 122, 132 based at least on the capacity information received from the standby gNB-CU-CPs 122, 132. The active gNB-CU-CP 112 may compare the load at the DUs 116a, 116b with the available capacity of the standby gNB-CU-CPs 122, 132 and allocate each DU to a standby gNB-CU-CP that has sufficient available capacity for the traffic of the allocated DU. The active gNB-CU-CP 112 may also determine the allocation for each DU taking into account load balancing between gNB-CU-CPs in the network.

[0040] In some example embodiments, the active gNB-CU-CP 112 may further determine the allocation of DUs 116a, 116b to the standby gNB-CU-CPs 122, 132 based on other factors, such as the geographic location of the standby gNB-CU-CPs 122, 132. For example, the active gNB-CU-CP 112 may allocate each of the DUs 116a, 116b to a standby gNB-CU-CP deployed near the DU to achieve low latency for traffic for the DUs.

[0041] The active gNB-CU-CP 112 may run an internal allocation algorithm to determine the allocation for the DUs 116a, 116b. The internal allocation algorithm may receive, for example, the capacity information and location of the standby gNB-CU-CP, the traffic load and location of the DUs, and optional additional data as input, and the internal allocation algorithm calculates an allocation solution for the DUs that scores high in terms of, for example, load balancing, delay, and / or other performance metrics. For ease of description, assume that Figure 3 In the example shown, the first DU 116a is assigned to the backup gNB-CU-CP 122, and the second DU 116b is assigned to the backup gNB-CU-CP 132.

[0042] At 216, the active gNB-CU-CP 112 may provide information of the standby gNB-CU-CP to the DU(s) assigned to the standby gNB-CU-CP. Figure 3In the example shown, at 216a, the active gNB-CU-CP 112 may provide information of the standby gNB-CU-CP 122 to the first DU 116a, and at 216b, provide information of the standby gNB-CU-CP 132 to the second DU 116b. The information of the standby gNB-CU-CP may include, for example, an IP address of the standby gNB-CU-CP. In one example, the information of the standby gNB-CU-CP may be communicated to the DU(s) via an F1 Application Protocol (F1AP) message (e.g., gNB CU Configuration Update).

[0043] At 218, the active gNB-CU-CP 112 may provide information of the DU(s) to the standby gNB-CU-CP to which the DU(s) are assigned. Figure 3 In the example shown, at 218a, the active gNB-CU-CP 112 may provide information of the first DU 116a to the standby gNB-CU-CP 122, and at 218b, provide information of the second DU 116b to the standby gNB-CU-CP 132. The information of the DU may include, for example, an identity of the DU, an identity of the CU-CP to which the DU is connected, and a core network function node such as an access and mobility management function (AMF) associated with the DU. In one example, the information of the DU may be communicated to the standby gNB-CU-CP via an Xn Application Protocol (XnAP) message (e.g., RAN Configuration Update).

[0044] In an example embodiment, at 218, if the active gNB-CU-CP 112 is aware of the downtime, the active gNB-CU-CP 112 may also provide downtime information to the standby gNB-CU-CP 122, 132. For example, if the active gNB-CU-CP 112 is configured with a planned downtime or the active gNB-CU-CP 112 receives a downtime indication from the core network, at 218, the active gNB-CU-CP 112 may provide the downtime information to the standby gNB-CU-CP 122, 132. The downtime information may indicate when and for how long the standby gNB-CU-CP 122, 132 is to be activated to operate as an active CU-CP node for the assigned DU.

[0045] At 220, the standby gNB-CU-CP 122, 132 may establish an inactive link for the DU assigned to the standby gNB-CU-CP 122, 132. Figure 3In the example shown, at 220a, the standby gNB-CU-CP 122 may establish an inactive link for the first DU 116a, and at 220b the standby gNB-CU-CP 132 may establish an inactive link for the second DU 116b. For example, the standby gNB-CU-CPs 122, 132 may establish an inactive Stream Control Transmission Protocol (SCTP) associated with the assigned DU, an inactive N2 interface with an AMF associated with the assigned DU, and optionally other inactive links for the assigned DU.

[0046] At 222, the standby gNB-CU-CP 122, 132 may begin data synchronization with the active gNB-CU-CP 112. Figure 3 In the example shown, at 222a, the standby gNB-CU-CP 122 may periodically receive synchronization data related to the first DU 116a assigned to the standby gNB-CU-CP 122 from the active gNB-CU-CP 112, and at 222b, the standby gNB-CU-CP 132 may periodically receive synchronization data related to the second DU 116b assigned to the standby gNB-CU-CP 132 from the active gNB-CU-CP 112. With the synchronization data, when the active gNB-CU-CP 112 is out of service, the standby gNB-CU-CPs 122, 132 may be activated to serve the assigned DUs 116a, 116b in place of the active gNB-CU-CP 112.

[0047] As described above, the active gNB-CU-CP 112 may periodically receive capacity information from the standby gNB-CU-CP 122, 132. If the received capacity information changes, for example, more UEs are RRC-connected to the standby gNB-CU-CP 122, 132 or some UEs are disconnected from the standby gNB-CU-CP 122, 132, and / or if the traffic load at the DU 116a, 116b changes, the active gNB-CU-CP 112 may trigger reallocation of the DU 116a, 116b. For ease of description, in Figure 3In the example shown, at 224, it is assumed that the active gNB-CU-CP 112 reassigns the first DU 116a to the standby gNB-CU-CP 132. Then, at 226, the active gNB-CU-CP 112 may provide information of the standby gNB-CU-CP 132 to the first DU 116a, and at 228, provide information of the first DU 116a to the standby gNB-CU-CP 132. At 230, the active gNB-CU-CP 112 may also indicate to the standby gNB-CU-CP 122 to which the first DU 116a was previously assigned that the allocation of the first DU 116a to the standby gNB-CU-CP 122 is released. In response to the allocation release indication, the standby gNB-CU-CP 122 may remove the inactive SCTP associations and other links of the first DU 116a.

[0048] At 232, the standby gNB-CU-CP 132 to which the first DU 116a is newly assigned may establish an inactive link for the first DU 116a and start data synchronization with the active gNB-CU-CP 112 at 234 to receive synchronization data related to the first DU 116a. It should be understood that operations 224, 226, 228, 232, 234 may be similar to operations 214, 216, 218, 220, 222 discussed above, and for convenience, repeated description of the details of these operations is omitted here.

[0049] At 236, the active gNB-CU-CP 112 may experience an unexpected failure or planned downtime, and the active gNB-CU-CP 112 no longer serves the DUs 116a, 116b. The active gNB-CU-CP 112 may send a failure indication to the standby gNB-CU-CP 122, 132 prior to the failure, or the standby gNB-CU-CP 122, 132 may detect the failure of the active gNB-CU-CP 112 via an XnAP message. For example, the standby gNB-CU-CP 122, 132 may periodically transmit XnAP messages to the active gNB-CU-CP 112 and monitor a response from the active gNB-CU-CP 112. If no response is received from the active gNB-CU-CP 112 within a predetermined time, the standby gNB-CU-CP 122, 132 may determine that the active gNB-CU-CP 112 has failed. Then, at 238, the standby gNB-CU-CP 122, 132 to which one or more DUs connected to the active gNB-CU-CP 112 have been allocated may be activated to operate as an active CU-CP node for the allocated one or more DUs, replacing the active gNB-CU-CP 112. It is assumed here that the first DU 116a is allocated to the standby gNB-CU-CP 122, and the second DU 116b is allocated to the standby gNB-CU-CP 132. At 238a, the standby gNB-CU-CP 122 may be activated for the first DU 116a, and at 238b the standby gNB-CU-CP 132 may be activated for the second DU 116b. It is worth noting that the standby gNB-CU-CP 122, 132 can be an active node of a different RAN instance with its own authority as described above, and in the activation operation 238, the standby gNB-CU-CP 122, 132 can be activated only for the DU 116a, 116b connected to the active gNB-CU-CP 112.

[0050] At 240a and 240b, when the standby gNB-CU-CP 122, 132 is activated, the standby gNB-CU-CP 122, 132 may send an activation complete message to the DU 116a, 116b, respectively. The DU 116a, 116b may know from the activation complete message that the standby gNB-CU-CP 122, 132 has taken over the role of the active gNB-CU-CP 112. The DU 116a, 116b may then deliver uplink UE data to the standby (now active) gNB-CU-CP 122, 132 and receive downlink data from the standby (now active) gNB-CU-CP 122, 132, respectively.

[0051] In an example embodiment, if the standby gNB-CU-CP 122, 132 is configured as a standby node for other active gNB-CU-CPs in addition to the active gNB-CU-CP 112, then at 242a and 242b, the standby gNB-CU-CP 122, 132 may be declared as a non-standby node to one or more of the other active gNB-CU-CPs, respectively. For example, after taking over the DU 116a, 116b, the standby gNB-CU-CP 122, 132 does not have sufficient available capacity for one or more other active gNB-CU-CPs. Then, the standby gNB-CU-CP 122, 132 may be declared as a non-standby node for one or more other active gNB-CU-CPs. The standby gNB-CU-CP 122, 132 may also remove inactive SCTP associations and other links established for DUs associated with the one or more other active gNB-CU-CPs. In an example embodiment, operations 242a, 242b may be omitted, and the standby gNB-CU-CP 122, 132 may report capacity information to other active gNB-CU-CPs as usual. Because the standby gNB-CU-CP 122, 132 has less capacity availability than before, the other active gNB-CU-CPs may release the allocation of DUs to the standby gNB-CU-CP 122, 132 and / or mark the standby gNB-CU-CP 122, 132 as a non-standby node.

[0052] In the process 200 discussed above, the active CU-CP 112 may periodically receive capacity information from multiple standby CU-CPs, and dynamically allocate DUs connected to the active CU-CP 112 to one or more of the multiple standby CU-CPs based on the received capacity information and optional other factors (such as the geographical locations of the multiple standby CU-CPs). This process can optimize resource allocation and implement load balancing between CU-CPs for services in the network, thereby improving user experience.

[0053] Figure 4 is a flow chart illustrating a method 300 according to an exemplary embodiment. The method 300 may be performed at an active gNB-CU-CP similar to the active gNB-CU-CP 112 discussed above. Figure 4 The steps shown in dashed boxes in FIG. 3 may represent optional steps that may be omitted in some example embodiments. In some example embodiments, method 300 may also include the steps described above with respect to Figure 3 One or more steps described above are performed at the active gNB-CU-CP 112. It should also be understood that reference has been made to Figure 3 Details of some steps in method 300 are discussed, and method 300 will be described here in a simplified manner.

[0054] like Figure 4 As shown, at 310, the active gNB-CU-CP 112 may send a capacity polling request to one or more gNB-CU-CPs configured as standby nodes for the active gNB-CU-CP 112, at 320, receive a capacity polling response including capacity information of the one or more standby gNB-CU-CPs from the one or more standby gNB-CU-CPs, and at 330, allocate at least one DU associated with the active gNB-CU-CP 112 to one of the one or more standby gNB-CU-CPs based at least on the capacity information of the one or more standby gNB-CU-CPs.

[0055] In an example embodiment, at least one of the one or more standby gNB-CU-CPs configured as standby nodes for the active gNB-CU-CP 112 may also operate as an active gNB-CU-CP in its own base station, which is different from the base station including the active gNB-CU-CP 112.

[0056] In an example embodiment, the active gNB-CU-CP 112 may allocate at least one DU to one of the one or more standby gNB-CU-CPs based at least further on the geographic locations of the one or more standby gNB-CU-CPs.

[0057] In an example embodiment, the capacity poll request may indicate the spare capacity requirement of the active gNB-CU-CP 112.

[0058] In an example embodiment, the received capacity information in the capacity poll response may indicate resources currently used at one or more standby gNB-CU-CPs or idle resources available at one or more standby gNB-CU-CPs.

[0059] In an example embodiment, the capacity polling request may be periodically sent to one or more standby gNB-CU-CPs, or the capacity polling request may include a periodic indication instructing one or more standby gNB-CU-CPs to periodically report capacity information.

[0060] In an example embodiment, the capacity poll response may be periodically received from one or more standby gNB-CU-CPs.

[0061] In an example embodiment, the capacity information received in the capacity poll response may indicate a change in resources currently used at one or more standby gNB-CU-CPs or a change in idle resources available at one or more standby gNB-CU-CPs.

[0062] In an example embodiment, at 340, the active gNB-CU-CP 112 may provide information of at least one DU to one of the one or more standby gNB-CU-CPs; and at 350, provide information of one of the one or more standby gNB-CU-CPs to at least one DU.

[0063] In an example embodiment, at step 340, the active gNB-CU-CP 112 may also provide downtime information to one of the one or more standby gNB-CU-CPs, which downtime information may indicate when and for how long the one of the one or more standby gNB-CU-CPs is to be activated as the active gNB-CU-CP for at least one DU.

[0064] In an example embodiment, the one or more standby gNB-CU-CPs configured for the active gNB-CU-CP 112 include a plurality of standby gNB-CU-CPs, and at 360, the active gNB-CU-CP 112 may reallocate at least one DU associated with the active gNB-CU-CP 112 to another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs in response to a change in at least one of: capacity information of the plurality of standby gNB-CU-CPs, or capacity information of one or more DUs associated with the active gNB-CU-CP 112. At 370, the active gNB-CU-CP 112 may also provide information of the at least one DU to another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs, and at 380, provide information of the at least one DU to another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs.

[0065] In an example embodiment, at 390, the active gNB-CU-CP 112 may also notify one of the plurality of standby gNB-CU-CPs to which the at least one DU was previously allocated that the allocation of the at least one DU is released.

[0066] Figure 5is a schematic flow chart illustrating a method 400 according to an exemplary embodiment of the present disclosure. The method 400 may be performed at a standby gNB-CU-CP similar to the standby gNB-CU-CP 122 or 132 discussed above. In some exemplary embodiments, the method 400 may also include the above-mentioned Figure 3 One or more steps described above are performed at the standby gNB-CU-CP 122 or 132. It should also be understood that the above reference has been made to Figure 3 Details of some steps in method 400 are discussed, and method 400 will be described in a simplified manner here. For ease of description, method 400 will be described below with respect to the standby gNB-CU-CP 122.

[0067] like Figure 5 As shown, at 410, the standby gNB-CU-CP 122 may receive a capacity polling request from one or more active gNB-CU-CPs, and in response to the received capacity polling request, send a capacity polling response to the one or more active gNB-CU-CPs at 420. The standby gNB-CU-CP 122 is configured as a standby node for the one or more active gNB-CU-CPs, and the capacity polling response may include capacity information for the standby gNB-CU-CP 122.

[0068] In an example embodiment, the capacity poll request may indicate spare capacity requirements of one or more active gNB-CU-CPs 112.

[0069] In an example embodiment, the capacity information of the standby gNB-CU-CP 122 may indicate resources currently used at one or more standby gNB-CU-CPs 122 or idle resources available at one or more standby gNB-CU-CPs 122.

[0070] In an example embodiment, the capacity poll request may be periodically received from one or more active gNB-CU-CPs, or the capacity poll request includes a periodic indication instructing the standby gNB-CU-CP 122 to periodically send capacity poll responses.

[0071] In an example embodiment, capacity poll responses may be periodically sent to one or more active gNB-CU-CPs.

[0072] In an example embodiment, the capacity information included in the capacity poll response may indicate resources currently being used at the standby gNB-CU-CP 122 or idle resources available at the standby gNB-CU-CP 122.

[0073] In an example embodiment, at 430, information of at least one DU is received from an active gNB-CU-CP among the one or more active gNB-CU-CPs, the at least one DU being associated with the active gNB-CU-CP among the one or more active gNB-CU-CPs and being allocated to the standby gNB-CU-CP 122.

[0074] In an example embodiment, at 430, the standby gNB-CU-CP 122 may also receive downtime information from one of the one or more active gNB-CU-CPs, which downtime information may indicate when the standby gNB-CU-CP 122 is to be activated as an active CU-CP node for at least one DU and for how long to be activated as an active CU-CP node for at least one DU.

[0075] In an example embodiment, at 440, the standby gNB-CU-CP 122 may receive an indication from an active gNB-CU-CP of the one or more active gNB-CU-CPs that an allocation of at least one DU associated with the active gNB-CU-CP of the one or more active gNB-CU-CPs is released.

[0076] In an example embodiment, at 450, if the standby gNB-CU-CP 122 is activated as an active CU-CP node for at least one DU assigned to the standby gNB-CU-CP 122 in response to a failure of one of the one or more active gNB-CU-CPs, the standby gNB-CU-CP 122 may be declared as a non-standby CU-CP node to at least one of the other active gNB-CU-CPs of the one or more active gNB-CU-CPs.

[0077] In the above example embodiment, the standby gNB-CU-CP 122 may operate as an active gNB-CU-CP in its own base station, which is different from the base station including one or more active gNB-CU-CPs.

[0078] Figure 6 5 is a schematic block diagram showing an apparatus 500 according to an exemplary embodiment of the present disclosure. The apparatus 500 may be implemented at a network node similar to the active gNB-CU-CP 112 to perform operations related to the active gNB-CU-CP 112 as described above. Figure 2-Figure 5 The operations related to the active gNB-CU-CP 112 are discussed in detail, so the blocks of the apparatus 500 will be briefly described here, and the details thereof may refer to the above description.

[0079] refer to Figure 6 , the apparatus 500 may include: a first component 510 for sending a capacity polling request from an active gNB-CU-CP 112 to one or more gNB-CU-CPs configured as standby nodes for the active gNB-CU-CP 112; a second component 520 for receiving a capacity polling response from the one or more standby gNB-CU-CPs, the capacity polling response including capacity information of the one or more standby gNB-CU-CPs; and a third component 530 for allocating at least one DU associated with the active gNB-CU-CP 112 to one of the one or more standby gNB-CU-CPs based at least on the capacity information of the one or more standby gNB-CU-CPs.

[0080] In an example embodiment, at least one of the one or more standby gNB-CU-CPs configured as a standby node for the active gNB-CU-CP 112 may also operate as an active gNB-CU-CP in its own base station, which is different from the base station including the active gNB-CU-CP 112.

[0081] In an example embodiment, the third component 530 may allocate at least one DU to one of the one or more backup gNB-CU-CPs based at least further on the geographic location of the one or more backup gNB-CU-CPs.

[0082] In an example embodiment, the capacity poll request may indicate the spare capacity requirement of the active gNB-CU-CP 112.

[0083] In an example embodiment, the received capacity information in the capacity poll response may indicate resources currently used at one or more standby gNB-CU-CPs or idle resources available at one or more standby gNB-CU-CPs.

[0084] In an example embodiment, the first component 510 may periodically send a capacity polling request to one or more standby gNB-CU-CPs. In another example embodiment, the capacity polling request may include a periodic indication indicating that one or more standby gNB-CU-CPs periodically report capacity information.

[0085] In an example embodiment, the second component 520 may periodically receive capacity poll responses from one or more standby gNB-CU-CPs.

[0086] In an example embodiment, the capacity information received in the capacity poll response may indicate a change in resources currently used at one or more standby gNB-CU-CPs or a change in idle resources available at one or more standby gNB-CU-CPs.

[0087] In an example embodiment, the apparatus 500 may further include a fourth component 540 for providing information of at least one DU to one of the one or more backup gNB-CU-CPs, and a component 550 for providing information of one of the one or more backup gNB-CU-CPs to at least one DU.

[0088] In an example embodiment, the fourth component 540 may also provide downtime information to one of the one or more standby gNB-CU-CPs together with information of the at least one DU. The downtime information may indicate when and for how long the standby gNB-CU-CP is to be activated as an active gNB-CU-CP for the at least one DU.

[0089] In an example embodiment, the one or more standby gNB-CU-CPs configured for the active gNB-CU-CP 112 include a plurality of standby gNB-CU-CPs, and the apparatus 500 may further include a sixth component 560 for reallocating at least one DU associated with the first CU-CP node to another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs in response to a change in at least one of the capacity information of the plurality of standby gNB-CU-CPs or the capacity information of one or more DUs associated with the active gNB-CU-CP 112. The apparatus 500 may further include a seventh component 570 for providing information of at least one DU to another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs, and an eighth component 580 for providing information of another standby gNB-CU-CP of the plurality of standby gNB-CU-CPs to at least one DU.

[0090] In an example embodiment, the apparatus 500 may further include a ninth component 590 for notifying one of the plurality of standby gNB-CU-CPs that allocation of at least one DU to which the at least one DU was previously allocated is released.

[0091] Figure 76 is a schematic block diagram showing an apparatus 600 according to an exemplary embodiment of the present disclosure. The apparatus 600 may be implemented at a network node similar to the standby gNB-CU-CP 122, 132 to perform operations related to the standby gNB-CU-CP 122, 132 as described above. Figure 2-Figure 5 The operations related to the standby gNB-CU-CP 122, 132 are discussed in detail, so the blocks of the apparatus 600 will be briefly described here, and the details thereof can refer to the above description. For ease of description, the apparatus 600 will be described below with respect to the standby gNB-CU-CP 122.

[0092] like Figure 7 As shown, the apparatus 600 may include: a first component 610 for receiving a capacity polling request from one or more active gNB-CU-CPs at a standby gNB-CU-CP 122, and a second component 620 for sending a capacity polling response to the one or more active gNB-CU-CPs in response to the received capacity polling request. The standby gNB-CU-CP 122 is configured as a standby gNB-CU-CP for the one or more active gNB-CU-CPs, and the capacity polling response may include capacity information of the standby gNB-CU-CP 122.

[0093] In an example embodiment, the capacity poll request may indicate spare capacity requirements of one or more active gNB-CU-CPs.

[0094] In an example embodiment, the capacity information of the standby gNB-CU-CP 122 may indicate resources currently being used at the standby gNB-CU-CP 122 or idle resources available at the standby gNB-CU-CP 122.

[0095] In an example embodiment, the first component 610 may periodically receive a capacity polling request from one or more active gNB-CU-CPs, and in another example embodiment, the capacity polling request may include a periodic indication instructing the standby gNB-CU-CP 122 to periodically send a capacity polling response.

[0096] In an example embodiment, the second component 620 may periodically send a capacity poll response to one or more active gNB-CU-CPs.

[0097] In an example embodiment, the capacity information included in the capacity poll response may indicate a change in resources currently being used at the standby gNB-CU-CP 122 or a change in idle resources available at the standby gNB-CU-CP 122.

[0098] In an example embodiment, the apparatus 600 may further include a third component 630 for receiving information of at least one DU from one of the one or more active gNB-CU-CPs, the at least one DU being associated with one of the one or more active gNB-CU-CPs and being allocated to the standby gNB-CU-CP 122.

[0099] In an example embodiment, the third component 630 may also receive downtime information from one of the one or more active gNB-CU-CPs, the downtime information indicating when the standby gNB-CU-CP 122 is to be activated as an active CU-CP node for at least one DU and for how long to be activated as an active CU-CP node for at least one DU.

[0100] In an example embodiment, the apparatus 600 may further include a fourth component 640 for receiving an indication from an active gNB-CU-CP of the one or more active gNB-CU-CPs that an allocation of at least one DU associated with the one of the one or more active gNB-CU-CPs is released.

[0101] In an example embodiment, the apparatus 600 may further include a fifth component 650 for declaring the standby gNB-CU-CP 122 as a non-standby CU-CP node to at least one of the other active gNB-CU-CPs among the one or more active gNB-CU-CPs, in a case where the standby gNB-CU-CP 122 is activated as an active CU-CP node for at least one DU assigned to the standby gNB-CU-CP 122 in response to a failure of one of the one or more active gNB-CU-CPs.

[0102] In the above example embodiment, the standby gNB-CU-CP 122 can operate as an active CU-CP node in its own base station, which is different from one or more base stations including one or more active gNB-CU-CPs.

[0103] Figure 8 7 is a schematic block diagram showing an apparatus 700 according to an exemplary embodiment of the present disclosure. The apparatus 700 may be implemented as an active gNB-CU-CP of the active gNB-CU-CP 112 as discussed above or as a standby gNB-CU-CP of the standby gNB-CU-CP 122 or 132 as discussed above.

[0104] like Figure 8As shown, the device 700 may include one or more processors 710, one or more memories 720 coupled to the processors 710, and one or more communication modules 730 coupled to the processors 710. The one or more memories 720 may have computer executable instructions 730 stored therein. The instructions 730 may cause the device 700 to implement the processes discussed above with respect to the gNB-CP-CU 112, 122, or 132 when executed by the one or more processors 710. The one or more communication modules 730 may implement any communication interfaces necessary to communicate with other network nodes or user equipment. If desired, the one or more communication modules 730 may include at least one antenna to facilitate radio communication with other network nodes or user equipment.

[0105] The one or more processors 710 may be of any appropriate type suitable for the local technology network and may include a general purpose processor, a dedicated processor, a microprocessor, a digital signal processor (DSP), one or more processors based on a multi-core processor architecture, and one or more of a dedicated processor such as one developed based on a field programmable gate array (FPGA) and an application specific integrated circuit (ASIC). The one or more processors 710 may be configured to control other elements of the device 700 and operate in cooperation with them to implement the processes discussed above with respect to the gNB-CP-CU 112, 122, or 132.

[0106] The one or more memories 720 may include at least one storage medium in various forms, such as volatile memory and / or non-volatile memory. Volatile memory may include, but is not limited to, for example, random access memory (RAM) or cache. Non-volatile memory may include, but is not limited to, for example, read-only memory (ROM), hard disk, flash memory, etc. In addition, the one or more memories 720 may include, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment or any combination thereof.

[0107] It should be understood that the blocks in the drawings can be implemented in various ways (including software, hardware, firmware, or any combination thereof). In some embodiments, one or more blocks can be implemented using software and / or firmware (e.g., machine executable instructions stored in a storage medium). In addition to or in place of machine executable instructions, some or all of the blocks in the drawings can be implemented at least in part by one or more hardware logic components. For example, but not limited to, illustrative types of hardware logic components that can be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), etc.

[0108] Some exemplary embodiments also provide computer program codes or instructions, which can make the equipment or device perform the above process when executed by one or more processors. The computer program code or instructions for implementing the process of the exemplary embodiments can be written in any combination of one or more programming languages. The program code or instructions can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device so that the program code enables the functions / operations specified in the flow chart and / or block diagram to be implemented when executed by the processor or controller. The program code can 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.

[0109] Some exemplary embodiments also provide a computer program product or computer readable medium in which computer program code or instructions are stored. A computer readable medium may be any tangible medium that may contain or store a program used by or in conjunction with an instruction execution system, device, or apparatus. A computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a computer readable storage medium would include an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0110] As used herein, “at least one of: ” and “at least one of ” and similar expressions, where a list of two or more elements is combined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0111] In addition, although operations are depicted in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown or in order, or performing all operations shown to achieve desired results. In certain cases, multitasking and parallel processing may be advantageous. Similarly, although several specific implementation details are included in the above discussion, these should not be interpreted as limitations on the scope of the present disclosure, but should be interpreted as descriptions of features that may be specific to a particular embodiment. The specific features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination.

[0112] Although the disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A first central unit control plane (CU-CP) node in a radio access network, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the first CU-CP node to at least: sending a capacity polling request to one or more second CU-CP nodes in the radio access network configured as standby CU-CP nodes for the first CU-CP node; receiving a capacity polling response from the one or more second CU-CP nodes, the capacity polling response including capacity information of the one or more second CU-CP nodes; as well as At least one distributed unit associated with the first CU-CP node is allocated to a second CU-CP node among the one or more second CU-CP nodes based at least on the capacity information of the one or more second CU-CP nodes. 2 . The first CU-CP node according to claim 1 , wherein the capacity polling request indicates a spare capacity requirement of the first CU-CP node.

3. The first CU-CP node according to claim 1, wherein the capacity information received in the capacity polling response indicates resources currently used at the one or more second CU-CP nodes or idle resources available at the one or more second CU-CP nodes.

4. The first CU-CP node according to claim 1, wherein the capacity polling request is periodically sent to the one or more second CU-CP nodes, or the capacity polling request includes a periodic indication instructing the one or more second CU-CP nodes to periodically report the capacity information. 5 . The first CU-CP node according to claim 1 , wherein the capacity polling response is periodically received from the one or more second CU-CP nodes.

6. The first CU-CP node according to claim 1, wherein the capacity information received in the capacity polling response indicates a change in resources currently used at the one or more second CU-CP nodes or a change in free resources available at the one or more second CU-CP nodes.

7. The first CU-CP node according to claim 1, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the first CU-CP node to at least: providing information of the at least one distributed unit to the one second CU-CP node among the one or more second CU-CP nodes; and The information of the one second CU-CP node among the one or more second CU-CP nodes is provided to the at least one distributed unit.

8. The first CU-CP node according to claim 7, wherein the first CU-CP node also provides downtime information to the one of the one or more second CU-CP nodes, the downtime information indicating when the one of the one or more second CU-CP nodes is to be activated as an active CU-CP node for the at least one distributed unit and how long it is to be activated as an active CU-CP node for the at least one distributed unit.

9. The first CU-CP node according to claim 1, wherein the one or more second CU-CP nodes include a plurality of second CU-CP nodes, and the at least one memory further stores instructions, which, when executed by the at least one processor, cause the first CU-CP node to at least: In response to a change in at least one of the following: the capacity information of the plurality of second CU-CP nodes, or the capacity information of one or more distributed units associated with the first CU-CP node, reallocating the at least one distributed unit associated with the first CU-CP node to another second CU-CP node among the plurality of second CU-CP nodes; providing information of the at least one distributed unit to the other second CU-CP node among the plurality of second CU-CP nodes; and The information of the another second CU-CP node among the plurality of second CU-CP nodes is provided to the at least one distributed unit.

10. The first CU-CP node according to claim 9, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the first CU-CP node to at least: The one second CU-CP node among the plurality of second CU-CP nodes is notified that the allocation of the at least one distributed unit associated with the first CU-CP node is released.

11. The first CU-CP node according to claim 1, wherein the first CU-CP node allocates the at least one distributed unit to the one second CU-CP node among the one or more second CU-CP nodes based at least on the geographical locations of the plurality of second CU-CP nodes.

12. The first CU-CP node according to claim 1, wherein at least one of the one or more second CU-CP nodes configured as the backup CU-CP node for the first CU-CP node operates as an active CU-CP node in a second base station, and the second base station is different from the first base station including the first CU-CP node.

13. A second central unit control plane (CU-CP) node in a radio access network, comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the second CU-CP node to at least: receiving a capacity polling request from one or more first CU-CP nodes in the radio access network, the second CU-CP node being configured as a standby CU-CP node for the one or more first CU-CP nodes; as well as In response to the received capacity polling request, a capacity polling response is sent to the one or more first CU-CP nodes, where the capacity polling response includes the capacity information of the second CU-CP node. 14 . The second CU-CP node according to claim 13 , wherein the capacity polling request indicates a spare capacity requirement of the one or more first CU-CP nodes. 15 . The second CU-CP node according to claim 13 , wherein the capacity information of the second CU-CP node indicates resources currently used at the second CU-CP node or idle resources available at the second CU-CP node. 16 . The second CU-CP node according to claim 13 , wherein the capacity polling request is periodically received from the one or more first CU-CP nodes, or the capacity polling request includes a periodicity indication instructing the second CU-CP node to periodically send the capacity polling response. 17 . The second CU-CP node according to claim 13 , wherein the capacity polling response is periodically sent to the one or more first CU-CP nodes.

18. The second CU-CP node according to claim 13, wherein the capacity information included in the capacity polling response indicates a change in resources currently used at the second CU-CP node or a change in idle resources available at the second CU-CP node.

19. The second CU-CP node according to claim 13, wherein the at least one memory further stores instructions, which, when executed by the at least one processor, cause the second CU-CP node to at least: Information of at least one distributed unit is received from one of the one or more first CU-CP nodes, where the at least one distributed unit is associated with the one of the one or more first CU-CP nodes and is allocated to the second CU-CP node.

20. The second CU-CP node according to claim 19, wherein the second CU-CP node also receives downtime information from the one of the one or more first CU-CP nodes, the downtime information indicating when the second CU-CP node is to be activated as an active CU-CP node for the at least one distributed unit and how long it is to be activated as an active CU-CP node for the at least one distributed unit.

21. The second CU-CP node according to claim 19, wherein the at least one memory further stores instructions, which when executed by the at least one processor, cause the second CU-CP node to at least: An indication is received from the one of the one or more first CU-CP nodes that allocation of the at least one distributed unit associated with the one of the one or more first CU-CP nodes is released.

22. The second CU-CP node according to claim 19, wherein the at least one memory further stores instructions, which when executed by the at least one processor cause the second CU-CP node to at least: In response to a failure of the one of the one or more first CU-CP nodes, the second CU-CP node is activated as an active CU-CP node for the at least one distributed unit assigned to the second CU-CP node, and declares itself as a non-standby CU-CP node to at least one of the other first CU-CP nodes among the one or more first CU-CP nodes.

23. The second CU-CP node according to claim 13, wherein the second CU-CP node configured as the backup CU-CP node for the one or more first CU-CP nodes operates as an active CU-CP node in a second base station, and the second base station is different from one or more first base stations including the one or more first CU-CP nodes.

24. A method comprising: sending a capacity polling request from a first central unit control plane (CU-CP) node in a radio access network to one or more second CU-CP nodes in the radio access network configured as standby CU-CP nodes for the first CU-CP node; receiving a capacity polling response from the one or more second CU-CP nodes, the capacity polling response including capacity information of the one or more second CU-CP nodes; as well as At least one distributed unit associated with the first CU-CP node is allocated to a second CU-CP node among the one or more second CU-CP nodes based at least on the capacity information of the one or more second CU-CP nodes.

25. The method of claim 24, wherein the capacity polling request indicates a spare capacity requirement of the first CU-CP node. 26 . The method of claim 24 , wherein the capacity information received in the capacity poll response indicates resources currently used at the one or more second CU-CP nodes or idle resources available at the one or more second CU-CP nodes.

27. The method according to claim 24, wherein the capacity polling request is periodically sent to the one or more second CU-CP nodes, or the capacity polling request includes a periodic indication instructing the one or more second CU-CP nodes to periodically report the capacity information.

28. The method of claim 24, wherein the capacity poll response is received periodically from the one or more second CU-CP nodes.

29. The method of claim 24, wherein the capacity information received in the capacity poll response indicates a change in resources currently used at the one or more second CU-CP nodes or a change in free resources available at the one or more second CU-CP nodes.

30. The method of claim 24, further comprising: Providing information of the at least one distributed unit to the one second CU-CP node among the one or more second CU-CP nodes; and The information of the one second CU-CP node among the one or more second CU-CP nodes is provided to the at least one distributed unit.

31. The method according to claim 30, wherein the first CU-CP node also provides downtime information to the one of the one or more second CU-CP nodes, the downtime information indicating when the one of the one or more second CU-CP nodes is to be activated as an active CU-CP node for the at least one distributed unit and how long it is to be activated as an active CU-CP node for the at least one distributed unit.

32. The method of claim 24, wherein the one or more second CU-CP nodes include a plurality of second CU-CP nodes, and the method further comprises: In response to a change in at least one of the following: the capacity information of the plurality of second CU-CP nodes, or the capacity information of one or more distributed units associated with the first CU-CP node, reallocating the at least one distributed unit associated with the first CU-CP node to another second CU-CP node among the plurality of second CU-CP nodes; providing information of the at least one distributed unit to the other second CU-CP node among the plurality of second CU-CP nodes; and The information of the another second CU-CP node among the plurality of second CU-CP nodes is provided to the at least one distributed unit.

33. The method of claim 32, further comprising: The one second CU-CP node among the plurality of second CU-CP nodes is notified that the allocation of the at least one distributed unit associated with the first CU-CP node is released.

34. The method according to claim 24, wherein the first CU-CP node allocates the at least one distributed unit to the one of the one or more second CU-CP nodes based at least on the geographic location of the one or more second CU-CP nodes.

35. The method of claim 24, wherein at least one of the one or more second CU-CP nodes configured as the backup CU-CP node for the first CU-CP node operates as an active CU-CP node in a second base station that is different from a first base station including the first CU-CP node.

36. A method comprising: receiving, at a second central unit control plane (CU-CP) node in a radio access network, a capacity polling request from one or more first CU-CP nodes in the radio access network, the second CU-CP node being configured as a standby CU-CP node for the one or more first CU-CP nodes; as well as In response to the received capacity polling request, a capacity polling response is sent to the one or more first CU-CP nodes, where the capacity polling response includes the capacity information of the second CU-CP node.

37. The method of claim 36, wherein the capacity polling request indicates a spare capacity requirement of the one or more first CU-CP nodes. 38 . The method of claim 36 , wherein the capacity information of the second CU-CP node indicates resources currently used at the second CU-CP node or idle resources available at the second CU-CP node.

39. The method of claim 36, wherein the capacity polling request is periodically received from the one or more first CU-CP nodes, or the capacity polling request includes a periodic indication instructing the second CU-CP node to periodically send the capacity polling response.

40. The method of claim 36, wherein the capacity poll response is periodically sent to the one or more first CU-CP nodes.

41. The method of claim 36, wherein the capacity information included in the capacity poll response indicates a change in resources currently used at the second CU-CP node or a change in free resources available at the second CU-CP node.

42. The method of claim 36, further comprising: Information of at least one distributed unit is received from one of the one or more first CU-CP nodes, where the at least one distributed unit is associated with the one of the one or more first CU-CP nodes and is allocated to the second CU-CP node.

43. The method according to claim 42, wherein the second CU-CP node also receives downtime information from the one of the one or more first CU-CP nodes, the downtime information indicating when the second CU-CP node is to be activated as an active CU-CP node for the at least one distributed unit and how long it is to be activated as an active CU-CP node for the at least one distributed unit.

44. The method of claim 42, further comprising: An indication is received from the one of the one or more first CU-CP nodes that allocation of the at least one distributed unit associated with the one of the one or more first CU-CP nodes is released.

45. The method of claim 42, further comprising: In response to a failure of the one of the one or more first CU-CP nodes, the second CU-CP node is activated as an active CU-CP node for the at least one distributed unit assigned to the second CU-CP node, and declares itself as a non-standby CU-CP node to at least one of the other first CU-CP nodes among the one or more first CU-CP nodes.

46. ​​The method of claim 36, wherein the second CU-CP node configured as a backup CU-CP node for the one or more first CU-CP nodes operates as an active CU-CP node in a second base station, and the second base station is different from one or more first base stations including the one or more first CU-CP nodes.

47. An apparatus comprising: means for sending a capacity polling request from a first central unit control plane (CU-CP) node in a radio access network to one or more second CU-CP nodes in the radio access network configured as backup CU-CP nodes for the first CU-CP node; means for receiving a capacity poll response from the one or more second CU-CP nodes, the capacity poll response comprising capacity information of the one or more second CU-CP nodes; as well as A component for allocating at least one distributed unit associated with the first CU-CP node to a second CU-CP node among the one or more second CU-CP nodes based at least on the capacity information of the one or more second CU-CP nodes.

48. An apparatus comprising: means for receiving, at a second central unit control plane (CU-CP) node in a radio access network, a capacity polling request from one or more first CU-CP nodes in the radio access network, the second CU-CP node being configured as a standby CU-CP node for the one or more first CU-CP nodes; as well as A means for sending a capacity polling response to the one or more first CU-CP nodes in response to the received capacity polling request, wherein the capacity polling response includes the capacity information of the second CU-CP node.

49. A computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: sending a capacity polling request from a first central unit control plane (CU-CP) node in a radio access network to one or more second CU-CP nodes in the radio access network configured as standby CU-CP nodes for the first CU-CP node; receiving a capacity polling response from the one or more second CU-CP nodes, the capacity polling response including capacity information of the one or more second CU-CP nodes; and At least one distributed unit associated with the first CU-CP node is allocated to a second CU-CP node among the one or more second CU-CP nodes based at least on the capacity information of the one or more second CU-CP nodes.

50. A computer-readable medium comprising instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, at a second central unit control plane (CU-CP) node in a radio access network, a capacity polling request from one or more first CU-CP nodes in the radio access network, the second CU-CP node being configured as a standby CU-CP node for the one or more first CU-CP nodes; and In response to the received capacity polling request, a capacity polling response is sent to the one or more first CU-CP nodes, where the capacity polling response includes the capacity information of the second CU-CP node.

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