Architecture for split functionality of radio access node arrangements

Abstract

An access node arrangement (20) with split layer functionality for operation in a radio access network, the access node arrangement comprising: at least two higher layer child nodes (300, 301), where each higher layer child node is configured to implement a higher layer (313) of a radio protocol stack for an individual core network connection; a lower layer child node (200) comprising a radio unit (215) and a communication interface (Fx) for parallel connection with the higher layer child node and configured to implement a lower layer (213) of a higher layer supporting the higher layer child nodes (300, 301) and to communicate lower layer data using the radio unit (215), whereby each higher layer child node (300, 301) obtains full support for the radio protocol stack; and a scheduler (214, 315) configured to manage an allocation of radio resources for a respective higher layer child node, where the scheduler is configured to manage an allocation of downlink data transmissions from a respective data buffer in the higher layer child node.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to various aspects of a radio access network of a wireless communication network. In particular, various architectures and functions of an access node arrangement of a radio access network are provided, including different entities or sub-nodes providing a splitting function of the access node arrangement. BACKGROUND

[0002] In radio communication systems, such as the generations provided through the Third Generation Partnership Project (3GPP), several releases of specifications have been provided for establishing and operating the wireless radio interface between wireless terminals and base stations and various operational levels of the wireless network. Broadly speaking, the wireless network can comprise a core network (CN) connected to other networks, such as the Internet. In order to provide access to the wireless network for wireless devices, a radio access network (RAN) is connected to the CN, especially for transferring control signaling and data signaling between the wireless terminals and the CN.

[0003] In 3GPP documents, the terminals are often referred to as user equipment (UE), and for brevity, the term will be used consistently herein. The RAN comprises a plurality of access nodes for providing radio access to the UEs. Each access node (also referred to as RAN node or base station) can provide connectivity within a so-called cell over an air interface. Various 3GPP releases relate to a radio communication specification referred to as 5G-type radio communication system (5GS), including a New Radio (NR) technology for the RAN, where the term gNB is used to identify an access node. The term gNB will also be used herein at least occasionally for the purpose of indicating an access node. In 5G, the core network is also referred to as 5GC.

[0004] 3GPP specifications for RAN provide for the use of a split of functions between a centralized unit (CU) and one distributed unit (DU) of an access node (gNB) that can be divided into two physical entities. The DU is placed close to the antenna and the CU is typically placed in a data server. The CU provides support for higher layers of the 5G NR protocol stack, such as SDAP (Service Data Adaptation Protocol), PDCP (Packet Data Convergence Protocol) and RRC (Radio Resource Control). The DU provides support for lower layers of the protocol stack, such as RLC (Radio Link Control), MAC (Medium Access Control) and PHY (Physical Layer). In practice, there can be a single CU per gNB, but one CU can control multiple DUs, e.g. more than 100 DUs can be connected to one CU. The interface between the CU and the DU is named Fl and according to 3GPP it should be an open interface, thus connecting one CU of one vendor to a DU of another vendor. In such split architecture, the CU can be placed in a data center, like the associated CN nodes. Therefore, it is expected that RAN CUs will be more integrated with the CN in the future, while the DU is the HW at the site close to the antenna.

[0005] The concept of a shared RAN has been proposed, where the RAN can be connected to several CNs belonging to different operators. Thereby, the HW in the RAN nodes can be shared by several operators and the spectrum can be shared, even for dedicated networks or small local operators that do not have its own spectrum, for example. In 3GPP, a RAN can be connected to more than one operator (with each operator having one CN), a so-called MORAN (Multi-Operator RAN). There is one interface per CN for both user and control plane. Data is added to a common user plane protocol stack in the RAN, where data is added to 5QI flows based on the respective QoS (Quality of Service).

[0006] A foreseeable scenario is that the number of micro operators will increase in the future, e.g. deployment of 6G in local areas as public or non-public networks or deployment of 6G distributed in many places. A micro operator can have its own CN but does not have any licensed spectrum or any access nodes. One solution is to use spectrum shared between many operators or it can use part of the spectrum and access nodes of a larger operator. This brings challenges regarding handling data traffic associated with different CNs. SUMMARY

[0007] The general objective is to provide solutions for the challenge of configuring a RAN to handle traffic associated with different CNs that can belong to different network operators. The proposed solutions herein are defined by the entries of the independent claims, while various embodiments are outlined in the dependent claims.

[0008] According to one aspect, there is provided an access node arrangement with split-layer functionality for operation in a radio access network. The access node arrangement comprises:

[0009] at least two higher-layer sub-nodes, wherein each higher-layer sub-node is configured to implement a higher layer of a radio protocol stack for an individual core network connection, i.e. each higher-layer sub-node is configured to connect to its associated core network belonging to its operator, and wherein the core networks can be different and independent from each other;

[0010] a lower-layer sub-node comprising a radio unit and a communication interface for a parallel connection to the higher-layer sub-nodes, and configured to implement a lower layer supporting the higher layers of the higher-layer sub-nodes, and to communicate lower-layer data using the radio unit, whereby each higher-layer sub-node obtains full support of the radio protocol stack; and

[0011] a scheduler configured to manage allocation of radio resources for the respective higher-layer sub-nodes, wherein the scheduler is configured to manage allocation of downlink data transmission from respective data buffers in the higher-layer sub-nodes.

[0012] According to another aspect, there is provided a higher-layer sub-node for use in an access node arrangement with split-layer functionality for operation in a radio access network. The higher-layer sub-node comprises:

[0013] an interface configured to provide a connection to one core network;

[0014] logic circuitry configured to implement a higher layer of a radio protocol stack; and

[0015] a communication interface configured for connection to a lower-layer sub-node configured to implement a lower layer supporting multiple higher-layer sub-nodes in parallel, wherein the higher-layer sub-node obtains full support of the radio protocol stack using the communication interface, the lower-layer sub-node comprising a radio unit configured to communicate lower-layer data.

[0016] In some variants, the higher-layer sub-node is configured as a master sub-node and configured to control the scheduler to manage allocation of downlink data transmission from respective data buffers in any other higher-layer sub-node connected to the lower-layer sub-node. Such other higher-layer sub-nodes can be referred to as slave sub-nodes.

[0017] In other variants, the higher layer child node is configured as a slave child node under the control of other higher layer child nodes operating as master child nodes. The slave node is configured to provide data, such as downlink data traffic to the UEs, to the lower layer child nodes over the communications interface. The slave node can include an interface to the scheduler under the control of the master child node to control the scheduler to manage allocation of downlink data transmissions from at least the data buffer.

[0018] According to another aspect, there is provided a lower layer child node for use in an access node arrangement having split layer functionality operating in a radio access network. The lower layer child node comprises:

[0019] a radio unit;

[0020] a communications interface configured to provide parallel connections with a plurality of higher layer child nodes of the access node arrangement, the higher layer child nodes each configured to implement higher layers of a radio protocol stack for individual core network connections;

[0021] logic circuitry configured to implement lower layers of a radio protocol stack supporting the higher layers of at least two higher layer child nodes and to communicate lower layer data, such as downlink data transmissions to the UEs, using the radio unit.

[0022] The lower layer child node is configured to receive data from respective data buffers in any of the connected higher layer child nodes for transmission by the radio unit in accordance with resource allocations determined by the scheduler.

[0023] The proposed solution and its various aspects stem from the understanding that most of the functionality and support of CUs and DUs can be implemented in data centers, in many cases the same data centers that the corresponding core networks are running in. With architectures like MORAN (Multi-Operator RAN) being used today, everything in the RAN except the radio carriers (antennas, towers, sites, power) is shared between two or more operators. In such solutions, all data is sent to the same common data center where the data is processed, and then the data is sent to the data centers where the different operators' core networks are running in / from these data centers to further distribution. Furthermore, data in the DL is handled in a common way using different available 5QI flows after it is sent to the RAN. It is not possible to control the load of each operator directly on the air interface.

[0024] On the other hand, the proposed solution provides an efficient architecture and operation of the shared access node, wherein the split functionality is defined with a lower layer part configured to operate in combination with a plurality of higher layer parts of different networks and operators. The lower layer entity is controllable to manage resource allocation and scheduling based on the network associated with the data. Thus, the proposed solution provides a technical solution that facilitates a convenient balance between the needs of micro-operators for spectrum usage and the needs of the operators owning the network to control traffic and usage. Downlink data transmission control of a common scheduler is enabled by having a separate data buffer for downlink data configured in the higher layer sub-node of any connection connected with the lower layer sub-node from which the downlink data transmission is performed. The scheduler can be controlled, e.g., by the master sub-node to pull or request data from the respective buffer based on the configured resource allocation and scheduling. This further allows for quick changes or adjustments of the prioritization of data packets from different higher layer sub-nodes, such as from different core networks. Such changes or adjustments of resource allocation to a particular higher layer sub-node can be caused, e.g., by different and alternating needs for latency or needs to transmit a complete set of data packets related to a common complete image frame. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various embodiments will be described with reference to the drawings.

[0026] Figure 1 A wireless network comprising a radio access network comprising at least two base stations is schematically illustrated, wherein each base station comprises a central unit and at least one distributed unit.

[0027] Figure 2A A split functionality and protocol layer handling in a RAN access node arrangement according to various examples of the proposed solution is schematically illustrated, wherein a common lower layer entity is provided.

[0028] Figure 2B An architecture of Figure 2A is schematically illustrated, further identifying that the distributed unit is split into a network specific part and a shared common lower layer part.

[0029] Figure 2C An example of an architecture similar to Figure 2A but with a different scheduler arrangement is schematically illustrated.

[0030] Figure 3 Functional elements included in a lower layer sub-node usable by a plurality of connected network specific higher layer sub-nodes according to various embodiments of the proposed solution are schematically illustrated.

[0031] Figure 4The functional elements included in the higher layer sub-nodes connectable with lower layer sub-nodes to obtain base station functionality for one network are schematically illustrated according to various embodiments of the proposed solution.

[0032] Figure 5 Signaling diagrams illustrating various signals and configuration steps that can be included in various embodiments of the proposed solution are illustrated. DETAILED DESCRIPTION

[0033] The present application will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the application are shown. The application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art.

[0034] It will be understood that when an element is referred to as being “connected” to another element, it can be directly connected to the other element or intervening elements can be present. In contrast, when an element is referred to as being “directly connected” to another element, there are no intervening elements present. Like reference numbers refer to like elements throughout. Furthermore, it will be understood that, although the terms first, second, etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present application. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0035] Well-known functions or constructions can not be described in detail for brevity and / or clarity. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0036] Embodiments of the application are described herein with reference to the accompanying drawings, which are meant to be illustrative of ideal embodiments of the application. As such, variations from the shapes and relative sizes of the regions illustrated in the drawings will be expected as a result of, for example, manufacturing processes and / or tolerances. Thus, embodiments of the application should not be construed as limited to the particular shapes and relative sizes of regions illustrated in the drawings, but rather, the embodiments of the application are to include deviations in shapes and relative sizes that result, for example, from different manufacturing processes and / or tolerances. Accordingly, the elements illustrated in the figures are schematic and not drawn to scale. It can be noted that where the disclosure refers to transmission or reception of information, this information can be conveyed in one or more messages.

[0037] Figure 1 A wireless network 100 useful for understanding the deployment of the proposed solution is illustrated. The wireless network 100 can be a radio communication network operating under the general and specific regulations and limitations published by 3GPP. The wireless network 100 can comprise a core network 110, which is connected to other networks, such as the Internet. The wireless network 100 further comprises an access network 120, which comprises a plurality of base stations or access nodes, of which a first base station 130 and a second base station 140 are shown.

[0038] Further, a UE 10 is illustrated, which can access the wireless network through any of the base stations comprised in the RAN 120. The UE 10 can be any device operable to wirelessly communicate with the network 100 through the base stations 130, 140, such as a mobile phone, a computer, a tablet, a M2M device, an loT device, etc.

[0039] In Figure 1In the RAN 120, at least two base stations 130 and 140 are configured with an architecture in which the base station functionality is divided into two different types of entities. In legacy 3GPP terminology, each access node 130, 140 can comprise a first entity as a Central Unit (CU) 131, 141 and a second entity as one or several Distributed Units (DU) 132, 133 and 142, 143, respectively. This architecture type is described, inter alia, in 3GPP Technical Specification TS 38.401, version 15.6.0, section 6, 15thedition. The CU is handling SDAP / PDCP / RRC and the DU is handling RLC / MAC / PHY. The CU and the DU are connected via a logical interface Fl, which can transport control signaling V1-C or data packets V1-U. Each DU serves one cell and has an associated cell ID. The actual transmission and reception point of the respective DU 132, 133, 142, 143 can be referred to as Transmission and Reception Point (TRP), which can be seen as a network node comprising or co-located with the antenna system of the respective DU.

[0040] The various aspects of the proposed solution will be described below with reference to the figures (in particular Figure 2A 、 Figure 2B 、 Figure 2C 、 Figure 3 and Figure 4 ). The proposed solution is based on the idea that different operators with different core networks should be able to share at least parts of the access node HW located close to the antennas and the associated SW for operating the HW. In this context, this HW and its logic circuitry is referred to as lower layer sub-node or LL-DU and contains the logic circuitry implementing the lower layers of the radio protocol stack (e.g. the 5G NR protocol stack). The LL-DU also includes an interface to the complementary part of the protocol stack, which is implemented in a different higher layer sub-node belonging to a different operator. In this context, a sub-node is a functional entity, which is a sub-portion of an access node (e.g. a gNB), which implements a part of the complete / entire radio protocol stack implemented by the access node. The proposed solution identifies one functional entity configured to implement the higher layers and one functional entity configured to implement the lower layers for an access node belonging to a network of one operator. A split is configured between the cooperating sub-nodes, where the functional entity handling the lower layers is configured in a lower layer sub-node (LL-DU) and the functional entity handling the higher layers is configured in a higher layer sub-node.

[0041] In one example, the lower layer comprises physical layer functions such as multiplexing, encoding and modulating DL data and correspondingly demodulating, decoding and demultiplexing UL data, as described in 3GPP Technical Specification 38.212. It also receives L1 control information and measurement results from the UE, mainly used in the scheduler for UL and DL data resource allocation. The lower layer can also comprise a MAC layer that receives data from the PHY, where the destination and quality of each data can be handled, e.g. where different QoS flows are handled. In the solution proposed herein, the MAC layer is also configured to send data to the correct sub-node forming the higher layer entity.

[0042] The functional entity handling the higher layer comprises a data buffer for DL data and operates a link layer protocol connected to each UE link with retransmission etc. The functional entity is further configured to implement the PDCP and SDAP layers and pass data to these higher layers, e.g. handling different QoS flows, as well as interfaces to the core network for the user plane and the RRC layer for the control plane. The RRC layer of the functional entity controls all connections between the access node, e.g. configured as a gNB, and the UE.

[0043] With the help of the LL-DU, each higher-layer child node obtains full support of the radio protocol stack, such that for each connected core network, a full base station functionality (such as a gNB) is obtained. In the context of a 5G RAN, full support can refer to a user plane protocol stack of SDAP / PDCP / RLC / MAC / PHY and a control plane protocol stack of RRC / PDCP / RLC / MAC / PHY. The split between the respective higher-layer child node and the lower-layer child node can be configured between RLC and PHY. The split can specifically be configured between RLC and MAC or between MAC and PHY. Furthermore, as will be further described, the split between the higher-layer child node and the lower-layer child node can differ from a traditional CU-DU split. The combined structure forms an access node arrangement, wherein each higher-layer child node is configured to form an individual base station with the common LL-DU, wherein each individual base station can be operated independently, e.g. by different operators. The higher-layer child nodes of the access node can be implemented in different data centers or clouds. The data transmitted over the air interface to / from the UE is controlled by a scheduler that allocates physical layer resources for downlink and uplink (e.g. as provided in 3GPP Technical Specification 38.300 clause 10.1), which can control the amount of radio resources used for each operator. Thus, the scheduler is configured to manage the allocation of radio resources for the respective higher-layer child node by extension for each network of the respective operator. In this context, the access network can be shared in at least some of the access nodes. On the other hand, the entire wireless network can not be shared, so that mobility can be configured to be handled according to the respective operators. According to some examples, the wireless network of the operator that owns and / or controls the LL-DU is referred to as the host network, including the host core network. The higher-layer child node of the host network is referred to herein as the host child node, wherein the combined LL-DU and host child node form the host access node. The host child node configures the LL-DU via the interface and controls the resource allocation in the LL-DU depending on the originating CN. The other wireless networks that utilize the LL-DU in the access node arrangement by connecting their higher-layer child nodes are referred to as slave networks. The higher-layer child node of the slave network is referred to herein as the slave child node.

[0044] Figure 2A A RAN architecture is illustrated according to various examples of the proposed solution, wherein various interfaces are shown. By way of example, four CNs are schematically shown with separate higher-layer child nodes of the access node arrangement 20, wherein higher-layer child nodes 300 and 301 are identified. The higher-layer child nodes of the access node arrangement 20 are all connected to the same (i.e. one common) lower-layer child node LL-DU 200. In other words, the different higher-layer child nodes of the access node arrangement 20 are used by different networks, while they all share the use of the common lower-layer child node 200.

[0045] In this figure, the master network is indicated on the right side, while the slave networks 1-3 are indicated on the left side. In this context, the master network configures the Fx communication interface between the LL-DU 200 and the transmission data buffers in the various higher layer sub-nodes by the master sub-node 300. The transmission data buffers are used to store DL data in the respective network’s higher layer sub-node until a scheduler has allocated resources for transmitting the data to the UE. Thus, the scheduler is configured to manage the allocation of downlink data from the respective data buffers in the higher layer sub-nodes. Once resources have been allocated, the scheduler indicates to the data buffers to send the buffered data to the LL-DU 200. In this context, it can be noted that the master sub-node 300 does not need to comprise data buffers and thus can be configured to control only one or more slave networks. The Fy interface is configured between the master sub-node 300 and the LL-DU 200 for providing control information to the LL-DU 200, including configuration and control signaling. The master sub-node 300 is further configured with a Fz interface to each higher layer sub-node of the slave networks, such as the slave sub-node 301.

[0046] Figure 2B Corresponding to Figure 2A but with a slight difference. Here, it is more clearly indicated that the RAN protocol stack of the access node arrangement 20 can maintain the CU-DU split (F1) for each network, but the DU comprises a further split to identify the (common) LL-DU 200. Thus, each higher layer sub-node 300, 301 comprises a CU and a part of a traditional DU. Thus, for each network, the access node arrangement 20 can identify three sub-nodes. For the example of the master network CN-M, the access node arrangement 20 can comprise a CU (CU_M) 300A, a DU (DU_M) 300B, and a UU-DU 200. For the example of the slave network CN-1, the access node arrangement 20 can comprise a CU (CU_1) 301A, one DU (DU_1) 301B, and a UU-DU 200.

[0047] From a user plane perspective, as illustrated, a lower layer split is defined between the MAC and the PHY or between the RFC and the MAC, with the scheduler 214 placed in the LL-DU. Then, the higher layer sub-nodes 300, 301 of different networks can be connected in parallel to the same LL-DU 200, i.e., such that the higher layer sub-nodes 300, 301 of different networks are connected to the same LL-DU 200 at the same time.

[0048] In this example, the scheduler 214 is located in the LL-DU 200. Thus, the management of resource allocation and scheduling of DL data is handled in the LL-DU 200. The LL-DU 200 is configured to control the DL data buffers in the respective higher layer child nodes 300, 301 based on the allocation of the scheduler 214 to send data to the LL-DU 200 over the corresponding Fx interface.

[0049] Figure 2C An alternative example is illustrated, where the scheduler 214 is included in the master child node 300, such as in the master DU (DU_M) 300B. Thus, the management of resource allocation and scheduling of DL data is configured to occur in the master child node 300. The master child node 300 is configured to control the DL data buffers in the respective higher layer child nodes 300, 301 based on the allocation of the scheduler 214 to send data to the LL-DU 200 over the corresponding Fx interface.

[0050] As illustrated in Figure 2A , Figure 2B and Figure 2C , the scheduler 214 is thus configured to manage the allocation of DL data from the respective data buffers in the higher layer child nodes 300, 301 as illustrated in these figures. In other words, each higher layer child node 300, 301 comprises a data buffer for holding DL data to be transmitted, and the scheduler 214 is configured to manage the resource allocation for all higher layer child nodes 300, 301 of the access node arrangement 20. This can include allocating resources depending on the core network association of the data, i.e. depending on the core network CN-1, CN-M connected to the higher layer child node 300, 301 holding the data.

[0051] In both examples of Figure 2B and Figure 2C , the DL RAN data link for each network utilizing the access node arrangement 20 thus ends in the buffers, after which the scheduler 214 decides which data from which higher layer entity 300, 301 to receive in the common LL-DU 200 for subsequent transmission over the radio link, e.g. to a UE. In the UL (uplink), the data belonging to different networks is distributed from the LL-DU 200 to the correct higher layer child node 300, 301 based on to which operator the data belongs.

[0052] The proposed solution enables the scheduler 214 to manage the resource allocation and scheduling based on what operator / network to prioritize handling. This can be based on the usage and agreements of available radio resources, which can vary over time. The resource management, including scheduling, can be based on the service associated with the data, latency requirements, amount of data, radio resources allowed by each operator, etc.

[0053] From a control plane perspective, broadcast signaling needs to be consistent with one source. According to an aspect of the proposed solution, broadcast signaling is performed from its higher layer child node 300 under control of one network (e.g. the host network). Furthermore, when a UE accesses a network (such as when initiating network registration), the host control layer 300C is hereby proposed for controlling radio resources for the CN of any connection, to handle this before connecting the UE to the relevant CN of the network the UE belongs to. This also involves control signaling. Thus, the host child node 300 can be configured to control signaling (such as broadcast and random access signaling) by the host control layer 300C, including sending messages in a random access procedure (as explained with reference to Figure 5

[0054] By way of example, this host control layer 300C will be referred to as a common control layer, and is occasionally exemplified herein as a host RRC 300C. The host RRC 330C can be configured to control random access signaling for any higher layer child node connected with a lower layer child node. This random access signaling can form part of a UE registration. In this context, registration can comprise a registration management procedure as described in 3GPP Technical Specification 4.2.2. This can also be managed by the host child node 300.

[0055] According to one example, broadcast signaling is sent from the host control layer 300C (e.g. an RRC implemented in the host child node 300), and down the protocol stack thereof to the LL-DU 200 for transmission out in an SSB (synchronization signal block). The LL-DU 200 is controlled by the host control layer 300C over the Fy interface. The host control layer 300C is controlled by the operations and management (O&M) of the host network (i.e. for the operator controlling and owning the right to use the spectrum for radio communication), whereas other control layers (RRCs) in the higher layer child nodes of the respective slave network (such as the control layer 301C in the higher layer child node 301) are partly controlled by the host control layer 300C (hereinafter mainly referred to as the host RRC 300C). Thus, the control layer 300C (e.g. an RRC) implemented by the host child node can be configured to control broadcast signaling for any higher layer child node of the access node arrangement 20.

[0056] ​In some examples, the master RRC 300C is implemented in a higher layer child node of the operator with traffic, i.e. the master RRC 300C is comprised in a higher layer child node 300 of the master network which also handles data traffic and comprises a data buffer. However, in alternative examples, the protocol stack of the master network is configured for the purpose of controlling access nodes for other (slave) networks only and without any UE camping, which means that UEs monitor the relevant system information and the paging channel of the cell on this channel, e.g. as defined in 3GPP Technical Specification 38.304 clause 5.2.5. In this example, the master child node 300 can not be configured to buffer any data to be transmitted on a data channel, such as a PDSCH (Physical Downlink Shared Channel).

[0057] The functions of the master RRC 300C are configured to handle broadcast information and random access reception at least for unregistered UEs. In some examples, random access messages received from registered UEs will be forwarded through the configured Fz interface to the corresponding RRC (e.g. 301C) in the higher layer child node (e.g. 301) of the network to which the UE belongs.

[0058] Once registered to one of the active operators connected with the access node arrangement 20, RRC signaling, mobility, etc. is handled in a dedicated RRC in the higher layer child node connected with the core network of the associated operator. By way of example, once a UE belonging to the slave network 1 is connected to this network through the access node arrangement 20, the RRC signaling with this UE is handled by the RRC 301C of the higher layer child node 301.

[0059] The master RRC 300C thus handles broadcast signaling as well as at least the initial steps of initial access and connection (e.g. through a random access procedure) of UEs belonging to any network connected with the access node arrangement 20 through the respective higher layer child node 300, 301. The master RRC 33OC can thus be configured to control random access signaling for any higher layer child node connected with the LL-DU 200. The master RRC and its associated / connected master CN define the common configuration of the RAN HW, e.g. information related to supported QoS (Quality of Service) flows, and the common RRC 300C and core network can thus communicate the configuration and limitations of the LL-DU node to the dedicated higher layer child nodes 301, e.g. through the configured Fz interface.

[0060] With reference to the traditional 5G standard, the proposed solution can identify the addition of a new lower layer sub-node 200 LL-DU containing the lower layers (PHY and optionally MAC). The LL-DU 200 also comprises a radio unit configured to transmit physical channels for the network of any connection, so the LL-DU 200 handles all transmissions and receptions over the air for the access node arrangement 20 for the core network of any connection. In some examples, a common scheduler 214 is included in the LL-DU 200.

[0061] With respect to mobility, the idle mode (also including RRC_Inactive) mobility is handled by the UE based on the PLMN the UE uses to identify the cell it can camp in. For the connected mode, it is beneficial for different operators to handle mobility separately, as one operator can share some access nodes with other operators, among others. Thus, the neighboring cells can be different for different operators. For the example of 5G, 3GPP refers to RRC_Connected (in the RAN) and CM-Connected (in the CN) to identify the connected mode.

[0062] Based on the architecture described herein, and as shown for example in Figures 2A to 2C the UE sees only one access node, where several PLMNs are listed in the broadcast information (provided by the master RRC 300C). Thus, the master RRC 300C of the higher layer sub-node 300 of the master network can be configured to control the LL-DU 200 to broadcast information identifying the network identity associated with the higher layer sub-node 300, 301 of any connection. From the UE’s perspective, in this context, the broadcast can appear as corresponding to a Multi-Operator Radio Access Network (MORAN) broadcast, which is a system concept where the same RAN is shared by two core networks of different operators with its own separate frequencies in the spectrum.

[0063] Figure 3 A lower layer sub-node 200 (also referred to herein simply as LL-DU 200) representing a lower layer entity is schematically illustrated according to various examples of the proposed solution, which can be commonly used by multiple operators and networks in the access node of the RAN.

[0064] The LL-DU 200 comprises logic circuitry 210 configured to control the operations. This can include data and signal transmission between one or more core networks and the air interface.

[0065] The logic circuitry 210 can include a processing device 211 comprising one or more processors, microprocessors, data processors, co-processors, and / or some other type of component that interprets and / or executes instructions and / or data. The processing device 211 can be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system-on-chip (SoC), an application-specific integrated circuit (ASIC), etc.). The processing device 211 can be configured to perform one or more operations based on an operating system and / or various applications or programs.

[0066] The logic circuitry 210 can also include a memory 212, which can include one or more memories and / or one or more other types of storage media. For example, the memory 312 can include random access memory (RAM), dynamic random access memory (DRAM), cache, read only memory (ROM), programmable read only memory (PROM), flash memory, and / or some other type of memory. The memory 212 can include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid-state disk, etc.). The memory 212 is configured to hold computer program code that can be executed by the processing device 211, where the logic 210 is configured to control the LL-DU 200 to perform any of the steps as provided herein. The software defined by this computer program code can include applications or programs that provide functionality and / or processes. The software can include device firmware, an operating system (OS), or various applications that can be executed in the logic circuitry 210.

[0067] The LL-DU 200 can implement lower layers 213 of a radio protocol stack (specifically, PHY and optionally MAC) that are used to carry data and support the higher layers of the radio protocol stack. This is handled by the program code and instructions of the logic circuitry 210 and in communication with the higher layers of the protocol stack supported in one or more separate higher layer sub-nodes, specifically in communication with the higher layer (primary) sub-node 300 of the primary network of the access node arrangement 20, as described. Thus, the LL-DU 200 is configured to provide connectivity with separate associated core networks CN-1, CN-M through each connected higher layer sub-node. In this context, each core network (e.g., CN-1) has a connection with one associated higher layer sub-node 301 of the access node arrangement 20, where the higher layer sub-node 301 is connected to the LL-DU 200 to implement the entire radio protocol stack in combination.

[0068] In various examples, the LL-DU 200 can further comprise a scheduler 214 configured to manage the allocation of resources for data transfer between the air interface and one or more connected networks. The allocation of resources to different networks can be made based on agreements between operators, QoS of data, priority of connections, signal quality to UEs, etc. In particular, the scheduler 214 can be configured with control information by the host or common RRC 300C of the higher layer child node of the connection to manage the allocation of resources for data transfer depending on the associated core network involved in the data transfer, as described.

[0069] The LL-DU 200 can further comprise a radio unit 215 comprising one or more radio transceivers for wireless communication with other sub-nodes of the radio communication network 100, such as UEs 10. Thus, the radio unit 215 can comprise a radio receiver and transmitter for communication over at least the air interface. The LL-DU 200 can implement the coverage of one cell of the wireless network of any connection. In other words, the LL-DU 200 can be configured with a cell identity shared by any connected higher layer child node of the access node arrangement 20.

[0070] The LL-DU 200 further comprises various interfaces 216 for data and control signaling, as described.

[0071] The Fx interface 216A is configured for the connected higher layer child node (and, by extension, for the respective associated core network). The Fx interface is particularly useful for receiving DL data from data buffers in the connected higher layer child node under the control of the scheduler 214. The Fx interface can also be used for transmitting UL data received from the UE over the air interface (Uu) to the associated higher layer child node 300, 301 and for control signaling.

[0072] The Fy interface 216B is configured for the host RRC 300C to configure and control the LL-DU 200 through a control network, such as the host network of the operator owning or managing the LL-DU 200. Thus, the interface Fy is a control interface configured to connect to one higher layer child node configured as a host sub-node to receive configurations for controlling signaling for the connected higher layer child node of any connection.

[0073] An interface 216C for connecting to an antenna for over-the-air communication can be included.

[0074] Figure 4A higher layer sub-node 300 representing a higher layer entity according to various examples of the proposed solution is schematically illustrated, which is operated by one single operator and thus associated with one network (e.g. a PLMN - Public Land Mobile Network). The higher layer sub-node 300 is configured to be used with the LL-DU 200 for forming an individual base station (e.g. a gNB) of a RAN for the associated network.

[0075] It can be noted that, Figure 4 The higher layer sub-node of the main network is indicated by reference sign 300, which is mainly used herein to identify the higher layer sub-node of the main network. However, the corresponding functionality and structure can be used in any higher layer sub-node of a secondary network (e.g. higher layer sub-node 301) unless specifically pointed out below.

[0076] The higher layer sub-node 300 can be configured exclusively in software code, which is configured to be run by logic circuitry to implement layers of a radio stack for communication with other entities such as the associated core network and the LL-DU 200. However, it will be described below as comprising logic circuitry. In some examples, the higher layer sub-node 300 can be co-located with one or more entities of the core network of the associated network, such as in a data center or in the cloud.

[0077] The higher layer sub-node 300 can comprise logic circuitry 310 configured to control operations. This can include data and signal transmission between one or more core networks and the air interface.

[0078] The logic circuitry 310 can comprise a processing apparatus 311 comprising one or more processors, microprocessors, data processors, co-processors, and / or some other type of component that interprets and / or executes instructions and / or data. The processing apparatus 311 can be implemented as hardware (e.g., a microprocessor, etc.) or a combination of hardware and software (e.g., a system-on-chip (SoC), an application-specific integrated circuit (ASIC), etc.). The processing apparatus 311 can be configured to perform one or more operations based on an operating system and / or various applications or programs.

[0079] The logic circuitry 310 can also include a memory 312, which can include one or more memories and / or one or more other types of storage media. For example, the memory 312 can include random access memory (RAM), dynamic random access memory (DRAM), cache, read only memory (ROM), programmable read only memory (PROM), flash memory, and / or some other type of memory. The memory 312 can include a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, a solid state disk, etc.). The memory 312 is configured to hold computer program code that can be executed by the processing device 311, with the logic circuitry 310 being configured to control the higher layer child node 300 to perform any of the steps as provided herein. The software defined by this computer program code can include applications or programs that provide functionality and / or processes. The software can include device firmware, an operating system (OS), or various applications that can be executed in the logic circuitry 310.

[0080] The higher layer child node 300 can implement higher layers 313 of the radio protocol stack (specifically RLC, SDAP, and PDCP) as well as RRC for the control plane. In case the higher layer child node is the master child node 300, the RRC can be configured as a master or common RRC 300C as described herein to at least partially control other higher layer child nodes 301 from the network. In case the higher layer child node is a slave child node 301, the RRC can be configured as a dedicated RRC 301C for that network. The higher layer implementation 313 is handled by program code and instructions of the logic circuitry 310 and operates in communication with lower layers of the protocol stack supported in the LL-DU 200.

[0081] In some examples, the higher layer child node 300 further includes a data buffer for buffering DL data.

[0082] In various examples, as indicated in Figure 2C The higher layer child node 300 can also include a scheduler 214 configured to manage allocation of resources configured by the LL-DU 200 for data transfer between the higher layer child node 300 and the air interface, in various examples. Specifically, the scheduler 214 can be configured with control information by the master RRC 300C to manage allocation of resources for data transfer depending on the core network of the associated connection involved in the data transfer, as described.

[0083] The higher layer subnode 300 is configured to operate in combination with the LL-DU 200 implementing the complementary part of the radio protocol stack, such that the combined higher layer subnode and LL-DU 200 implement a complete radio protocol stack, wherein the implementation layer of the LL-DU 200 carries data of the implementation layer of the higher layer subnode, and wherein the LL-DU 200 further comprises a radio unit for communication over at least an air interface.

[0084] The higher layer subnode 300 further comprises various interfaces 316 for data and control signaling, as described.

[0085] The Fx interface 316A is configured to be connected to the LL-DU 200. The Fx interface is especially useful for receiving data from the LL-DU 200 in the UL, and for feeding data from a data buffer 31 (which is comprised in the higher layer subnode 300) under control of a scheduler 214 (comprised in the higher layer subnode 300 or in the LL-DU 200), wherein such data buffer is comprised in the higher layer subnode 300. The Fx interface can also be used for control signaling.

[0086] The Fy interface 316B is comprised in a higher layer child node operating as master child node 300. The Fy interface is configured to connect the RRC 300C of the master child node 300 to the LL-DU 200 and can be used to configure the LL-DU 200. This can include transmitting a configuration to the LL-DU 200, which, when a scheduler 214 is comprised in the LL-DU 200, is used to manage the resource allocation, including scheduling, of any higher layer child node 300, 301 connected to the LL-DU 200. Thus, the master child node 300 can be configured to control the scheduler 214 to manage the allocation for higher layer child nodes 300, 301 connected with the LL-DU 200 in the access node arrangement 20. By means of the interface Fy, the LL-DU 200 can receive a configuration for controlling the signaling for the allocation of any connected higher layer child node. Based on the received configuration, the LL-DU 200, when comprising a scheduler 214, can be configured to control the scheduler 214 to manage the allocation for any connected higher layer child node. As exemplified herein, this control by the master child node 300 can include transmitting control information that controls the resource allocation depending on the core network association of the respective connected higher layer child node 300, 301. Thus, the scheduler can be configured by the control information to manage the allocation based on the core network the UE is associated with, i.e. based on or depending on the originating core network for the DL and the terminating core network for the UL. In this context, the control information can be configured depending on operator agreements, such as between the operator of the master network and the operator of the slave network, which set ranges and limits for e.g. bandwidth and latency. In this context, the control information can configure the scheduler to prioritize the resource allocation based on which core network the data to be scheduled is associated with, where the data originates from or where it is destined to. In other words, the scheduler can be configured to manage the allocation with priority based on the requesting core network.

[0087] A Fz interface 316C can also be comprised. The Fz interface is configured to connect the RRC of a higher layer child node with the RRC of other higher layer child nodes. In case the higher layer child node is a master child node 300, the Fz interface can connect its master RRC 300C to one or more RRCs 301c of respective slave networks. In case the higher layer child node is a slave child node 301, the Fy interface can connect its RRC 301C to the master RRC 300C of the master child node 300. Thus, the interface Fy is used for configuration and control between higher layer child nodes by a controlling network, such as the master network of the operator owning or managing the master child node 300.

[0088] Also comprised is an interface 316D configured for connection with a core network (CN), such as a single CN, which can be the core network CN-M of the master network or the core network CN-1 of the slave network 1, for example. In other words, in the architecture of the access node arrangement 20, each higher layer subnode comprises an interface 316D configured to provide a connection with a separate core network.

[0089] In some examples, as indicated by the dashed lines in Figure 4 and as indicated in Figure 2B and Figure 2C , the access node arrangement 20 can be configured such that (here exemplified for the master network) the higher layer subnode 300 comprises a CU 300A (CU_M) and an RLC of at least a DU (DU_M). In this context, the higher layer subnode 300 comprises a first part of a CU and a DU of a traditional CU-DU split. Thus, the higher layer subnode 300 is connectable to a LL-DU 200 implementing a second lower layer part common to multiple DU parts of different higher layer subnodes 300, 301. In examples maintaining this traditional CU-DU split, as shown by the example in Figure 2B , the access node arrangement 20 thus comprises multiple CUs CU_1, CU_M and multiple DUs DU_1, DU_M. The respective higher layer subnode 300, 301 implements one of these CUs 300A, 201A and a first DU part 300B, 301B of one of these DUs, respectively. The LL-DU 200 implements a second lower layer DU part 213 common to multiple DUs. In this context, the first DU part 300B, 301B and the second lower layer DU part 213 provide a combined implementation of layers of one DU. For the example of the slave network 1, the access node arrangement 20 is configured with a CU (CU_1) 301A and a DU part (DU_1) 301B in the higher layer subnode 301 and a second lower layer DU part 213 implemented in the LL-DU 200. Figure 5 A signaling diagram of the proposed solution is shown, which schematically shows signals and configurations between the various subnodes.

[0090] Two different UEs 1 and 2 are indicated, of which at least UE 2 is initially not registered to its network.

[0091] A LL-DU (lower layer subnode) 200 is shown, which is being configured by a higher layer subnode 300 of a master network to connect to the master network and at least one additional slave network comprising a higher layer subnode 301. The higher layer subnodes 300, 301 are here shown with two subparts 300A, 300B and 301A, 301B, respectively, similar to Figure 2B and Figure 2CAnd as referenced Figure 4 As described.

[0092] The higher-layer child node 300 of the main network includes a sub-part 301A labeled gNB-CU (primary). This sub-part 301A supports and processes SDAP, PDCP, and primary RRC 300C, and is specifically operated to configure other connected higher-layer child nodes 301 and lower-layer child nodes 200. The higher-layer child node 300 of the main network also includes a sub-part 300B labeled gNB-DU (primary), which includes a sub-part with conventional DU functions as described. This sub-part 300B implements and processes RLC for the main network and may also include a data buffer.

[0093] Correspondingly, a higher-level child node 301 of the slave network that does not own or control the lower-level child node 200 includes a sub-part 301A labeled gNB-CU1, which includes CU functionality. This sub-part 301A implements and handles the slave network's SDAP, PDCP, and network-specific RRC 301C. The higher-level child node 301 of the slave network also includes a sub-part 301B labeled gNB-DU1, which includes a sub-part of the conventional DU functionality as described. This sub-part 301B implements and handles the RLC for the slave network and includes a data buffer. As described above, interfaces F1, Fx, Fy, and Fz are indicated at the top of the graph between cooperating entities.

[0094] Based on the following, various aspects and examples of the proposed solution are illustrated in the diagram:

[0095] -501 indicates that an Fl interface is established between the main CU part (CU_M) 300A and the main DU part (DU_M) 300B in the main-child node 300.

[0096] - At 502, using the Fl interface, perform configuration steps between sub-section 300A (CU_M) and sub-section 300B (DU_M).

[0097] -503 indicates the establishment of the Fy interface between the master-slave node 300 (specifically its CU part 300A) and the LL-DU 200.

[0098] - At 504, using the FY interface, perform the radio configuration steps between subsection 300A and LL-DU 200.

[0099] -505 indicates the establishment of the Fz interface between the master child node 300 and the higher-level child node 301. Specifically, the interface Fz is established between the master RRC 300C of the master CU section 300A and the RRC 301C of the slave CU section 301A.

[0100] - At 506, using the Fz interface, configuration steps of the cell are performed between the master CU 300A and the slave CU 301 A (each).

[0101] - 507 indicates the establishment of the Fx interface between the master subnode 300 (in particular its DU part 300B) and the LL-DU 200.

[0102] - 508 indicates the configuration of the FX, further indicated, performed by the master subnode 300, here exemplified by the master DU 300B

[0103] - 509 indicates the establishment of the Fl interface in the slave subnode 301 between the slave CU part (CU_1) 301 A and the slave DU subpart (DU_1) 301 B. This corresponds to step 501.

[0104] - At 510, using the Fl interface, configuration steps are performed between the subpart 301 A (CU_1) and the subpart 301 B (DU_1), corresponding to step 502.

[0105] - 511 indicates the establishment of the Fx interface between the slave subnode 301 (in particular its DU part 301 B) and the LL-DU 200. This corresponds to step 507.

[0106] - 512 indicates the configuration of the FX, further indicated, performed by the slave subnode 301, here exemplified by the slave DU 301 B. This corresponds to step 508.

[0107] - 513 indicates that the broadcast channel is transmitted from the master subnode 300, from the master CU 300A through the master DU 300B to the LL-DU 200, to be transmitted over the air by radio on a physical channel. In step 506, information related to the slave network such as the PLMN identity to be included in the broadcast signaling can be obtained in the master CU 300A from the slave CU 301a. The access node arrangement 20 comprising the LL-DU 200 as well as the higher layer entities 300 and 301 provides individual base station (e.g. gNB) functionality for both the master network and the slave network. The broadcast signal and SSB can be received by UEs in the area such as UE1 and UE2.

[0108] -514 indicates a first step in a random access procedure (RACH) for connecting the UE 2 to its associated network, using the access node arrangement 20 as a slave network. The RACH procedure is also referred to as initial access and involves a series of procedures between the UE 2 and the access node arrangement 20 in order for the UE to acquire uplink synchronization and obtain a designated ID for radio access communication. The random access procedure includes a random access transmission (e.g. Msg. 1) from the UE 2, which is received in the LL-DU 200. The random access transmission can be referred to as a preamble, which can constitute a random access request (such as a random access channel (RACH) request). In one example, the master subnode 300 is configured to handle the initial step of the RACH also for UEs belonging to the slave network, as will be described below. In such example, the random access message is transferred from the LL-DU 200 to the master CU 300A.

[0109] -515 indicates that the master CU 300A responds with a random access response message through the LL-DU 200.

[0110] -516 indicates that the UE 2 transmits a Msg. 3 including the ID of the UE 2, which is received in the LL-DU 200 and transmitted up to the master CU 300A. The master CU 300A forwards or reports the message to the slave CU 301A of the network associated with the UE 2 based on network information included in or determined based on the Msg. 3. This can lead to the conclusion that the master subnode 300 is involved in the RACH procedure. In other words, the master RRC 300C in the master CU can be configured to forward messages received from the UE 2 after receiving the random access request. Forwarding to the RRC (301C) of the higher layer entity corresponding to the network association based on a subsequent message (e.g. Msg. 3) received from the UE indicating the network association. Thus, the RRC 301C of the slave subnode (i.e. the slave CU 301A) is configured to receive messages (e.g. Msg. 3) from the master subnode 300A over the RRC interface Fz (which originate from the UE 2) following the random access request (e.g. Msg. 1).

[0111] -517 the UE 2 performs connection setup with the correct network (i.e. via the slave DU 301B with the slave CU 301A) through the LL-DU 200. The slave CU 301A is also connected to the relevant slave core network CN-1 (not shown here).

[0112] - 518 indicates a DL transmission of data from the core network CN-1. The data is transmitted from the CU 301 A to a buffer 314 in the slave node 301 B with support of the protocol layers. From there, the data is scheduled and communicated to the UE 2 by the LL-DU 200. As mentioned, the scheduler 214 can be comprised in the LL-DU 200 or in the master DU 300B. Figure 5 The remaining steps relate to the example where the scheduler 214 is comprised in the LL-DU 200. An alternative example where the scheduler 214 is comprised in the master DU 300B will be briefly described further.

[0113] - 519 indicates a transmission of a DL buffer status report (BSR) from the slave node 301 B to the scheduler 214 comprised in the LL-DU 200, the BSR indicating the data received at 518. For the alternative example where the scheduler 214 is comprised in the master DU 300B, the BSR is transmitted to the master DU 300B.

[0114] The resource allocation and scheduling can be performed by the scheduler 214 based on control information obtained in or from the master node 300. In case the scheduler 214 is comprised in the LL-DU, the control information can be obtained using the Fy interface. Obtaining the control information in the LL-DU 200 can occur at step 504 or later corresponding to step 504, such as after the Fz setup and configuration of steps 505 and 506 has been established. The control information can determine, for example, an indication of allowed bandwidth or latency and / or priority to obtain resource allocation in relation to other networks using the access node arrangement 20.

[0115] - 520 indicates that the scheduler (in the LL-DU 200) sends a DL data request to the slave node 301 B, the request indicating the scheduling determined by the scheduler 214. The DL data request informs the slave node 301 B using the radio unit 215 how much data to send to the LL-DU 200 for data transmission and when to send it.

[0116] - At 521, data from the buffer in the slave DU 301 B is transmitted by the LL-DU 200 to the UE 2 according to the resource allocation determined by the scheduler 214 based on the DL data request of 520.

[0117] - 522 indicates an UL transmission of data from the UE 2 in connected mode, where the data is received in the LL-DU 200 and communicated to the associated higher layer node 301 for further transfer to its core network CN-1.

[0118] According to what is described herein, the scheduler 214 can be configured by the master subnode 300 to allocate with priority management based on the requesting core network. This way, the master network, which owns or manages the spectrum in the cell, can keep control of the data traffic. Moreover, this allows the operator of the master network to schedule based on different agreements with the operators of the slave networks, such as by controlling the scheduler 214 to manage resource allocation for different high layer subnodes 3001 based on different requirements on e.g. latency and / or bandwidth.

[0119] According to an aspect of the proposed solution previously described and exemplified, a common RAN node architecture is provided for an access node arrangement 20 with split layer functionality, wherein the access node arrangement comprises:

[0120] at least two higher layer subnodes 300, 301, wherein each higher layer subnode is configured to implement higher layers 313 of a radio protocol stack for an individual core network connection;

[0121] a lower layer subnode 200 shared by the higher layer subnodes 300, 301, comprising a radio unit 215 and configured to implement lower layers 213 supporting the higher layers of the at least two higher layer subnodes 300, 301 and to communicate lower layer data using the radio unit 215;

[0122] wherein the higher layer subnodes have respective communication interfaces Fx for parallel connection with the lower layer subnode, whereby each higher layer subnode 300, 301 obtains full support of the radio protocol stack. In this context, parallel connection means that each higher layer subnode 300, 301 is individually and independently connected to the lower layer subnode 200 for in / out data communication to / from the individual core network the respective higher layer subnode 300, 301 is connected to. Thus, the higher layer subnodes are associated with separate core networks but share the lower layer subnode 200.

[0123] Hence, when connected to operate with the lower layer subnode 200, each higher layer subnode 300, 301 will form an individual base station, such as a gNB, wherein each base station can be individually operated, e.g. by different operators. In this context, the access node arrangement comprises a single lower layer subnode 200 connectable to multiple higher layer subnodes 300, 301.

[0124] The proposed solution also provides the benefit that the actual HW required at the air interface as well as the spectrum can be conveniently shared, while the functionality of the base stations, which can be configured by logical circuitry operating on software, can be configured elsewhere and separately for each operator, such as in connection with the associated core network. This provides a way of reusing HW, which saves at least material and energy required.

[0125] According to another aspect, the proposed solution provides a lower layer sub-node 200 of an access node arrangement 20 with split-layer functionality for operation in a RAN, wherein the lower layer sub-node 200 comprises:

[0126] a radio unit 215;

[0127] a communication interface Fx configured to provide a parallel connection with a plurality of higher layer sub-nodes 300, 301 of the access node arrangement, which are each configured to implement higher layers of a radio protocol stack for an individual core network connection; and

[0128] a logic circuitry 210 configured to implement lower layers 213 of a radio protocol stack supporting the higher layers of the at least two higher layer sub-nodes 300, 301 and to use the radio unit 215 for communicating lower layer data.

[0129] Hence, the lower layer sub-node 200 forms a base station sub-unit of a complete base station, such as a gNB, configured by connecting the lower layer sub-node 200 to higher layer sub-nodes. In particular, a plurality of individual base stations sharing the common lower layer sub-node 200 can be configured, wherein each base station can be individually operated, e.g. by different operators. The proposed solution also provides the benefit that the actual HW required at the air interface can be conveniently shared, while the functionality of the base station, which can be configured by logic circuitry operating on software, can be configured elsewhere and separately for each operator, such as in connection with the associated core network. This provides a way of reusing HW, which saves at least material and energy required. In addition, a host operator, i.e. the operator of the host network, owning or managing the right to the radio spectrum and controlling the lower layer sub-node 200, can allow other operators to connect to the lower layer sub-node and obtain scheduling and resource allocation under the control of the host operator or by agreement with the host operator.

[0130] According to another aspect, the proposed solution provides a higher layer sub-node 300 (or 301) for use in an access node arrangement 20 with split-layer functionality for operation in a radio access network, wherein the higher layer sub-node comprises:

[0131] an interface 316D configured to provide a connection with one core network CN-1, CN-M;

[0132] a logic circuitry 310 configured to implement higher layers 313 of a radio protocol stack; and

[0133] a communication interface Fx configured for connection 200 with a lower layer child node configured to implement a lower layer 213 of a higher layer supporting in parallel a plurality of higher layer child nodes, the lower layer child node comprising a radio unit 215 configured to communicate lower layer data.

[0134] wherein the higher layer child nodes use the communication interface to obtain full support of a radio protocol stack.

[0135] Thus, the higher layer child nodes 300, 301 form base station sub-units of a complete base station, such as a gNB, configured by connection to the lower layer child node 200. The proposed solution provides for a split of the interface Fx to the lower layer unit comprising the HW required for radio communication at the air interface, which can conveniently be shared with other higher layer child nodes. On the other hand, the functionality of the base station, which can be configured by logical circuitry operating in software, can be configured elsewhere and separately for each operator. This provides greater flexibility for the operators in terms of computing infrastructure by, for example, providing the ability to configure the higher layer child nodes in conjunction with the associated core network. In addition, an operator that does not own its own spectrum can connect to the lower layer child node 200 of the main network and obtain scheduling and resource allocation under the control of or by agreement with the operator that owns or manages the spectrum.

[0136] According to another aspect, the proposed solution provides an access node arrangement 20 with split layer functionality for operation in a radio access network, wherein the access node arrangement comprises:

[0137] at least two higher layer child nodes 300, 301, wherein each higher layer child node is configured to implement a higher layer 313 of a radio protocol stack for an individual core network connection 316D;

[0138] a lower layer child node 200 shared by the higher layer child nodes 300, 301, comprising a radio unit 215 and configured to implement a lower layer 213 of a higher layer supporting the at least two higher layer child nodes 300, 301 and to communicate lower layer data using the radio unit 215; and

[0139] a scheduler 214;

[0140] wherein one of the higher layer child nodes is a master child node configured to control the scheduler to manage allocation of resources for data communication of any of some of the higher layer child nodes connected with the lower layer child node.

[0141] Thus, the proposed access node arrangement 20 provides an architecture in which the higher layer sub-nodes 300, 301 each form a base station sub-unit of a complete base station (such as a gNB) configured by connecting to a lower layer sub-node 200, and in which a master network controls the resource allocation and scheduling of all base stations of the access node arrangement 20. This provides the additional benefit that the resource allocation and scheduling for data traffic can be configured differently depending on the originating (or terminating) network. This allows an operator that does not own its own spectrum rights to conveniently connect its higher layer sub-nodes 301 to the lower layer sub-nodes 200 of a master network and obtain a reasonable level of resource allocation based on an agreement with the operator of the master operator that owns or manages the spectrum. At the same time, the proposed solution allows the master operator to retain control both in terms of scheduling and by controlling and performing broadcast signaling.

[0142] The various aspects of the proposed solution have been outlined in the foregoing. Any of the details and examples provided herein can be combined in any way or form, or according to any combination of the features of the following clauses.

[0143] Clause 1. An access node arrangement (20) with split layer functionality for operation in a radio access network, the access node arrangement comprising:

[0144] at least two higher layer sub-nodes (300, 301), wherein each higher layer sub-node is configured to implement a higher layer (313) of a radio protocol stack for an individual core network connection;

[0145] a lower layer sub-node (200) comprising a radio unit (215) and a communication interface (Fx) for parallel connection with the higher layer sub-nodes, and configured to implement a lower layer (213) supporting the higher layer of the higher layer sub-nodes (300, 301), and to transmit lower layer data using the radio unit (215), whereby each higher layer sub-node (300, 301) obtains full support of the radio protocol stack; and

[0146] a scheduler (214, 315) configured to manage allocation of radio resources for the respective higher layer sub-node, wherein the scheduler is configured to manage allocation of downlink data transmission from respective data buffers in the higher layer sub-nodes.

[0147] Clause 2. The access node arrangement according to clause 1, wherein the higher layer sub-nodes are associated with separate core networks.

[0148] Clause 3. The access node arrangement according to clause 1 or 2, wherein the scheduler (214) is comprised in one of the higher layer sub-nodes (300).

[0149] Item 4. The access node arrangement according to item 1 or 2, wherein the scheduler (214) is comprised in the lower layer subnode.

[0150] Item 5. The access node arrangement according to any preceding item, wherein the scheduler is configured to manage the allocation in dependence of the core network association of the respective higher layer subnode.

[0151] Item 6. The access node arrangement according to any preceding item, wherein the scheduler is configured to manage the allocation with priority based on the requesting core network.

[0152] Item 7. The access node arrangement according to any preceding item, wherein one of the higher layer subnodes is a master subnode configured to control signalling for the higher layer subnode.

[0153] Item 8. The access node arrangement according to item 7, wherein the master subnode is configured to control the scheduler to manage the allocation for the higher layer subnode.

[0154] Item 9. The access node arrangement according to item 7 or 8, wherein the master subnode does not comprise a data buffer.

[0155] Item 10. The access node arrangement according to any of items 7 to 9, wherein the master subnode implements a radio resource control layer, RRC (300C), configured to control broadcast signalling for the higher layer subnodes.

[0156] Item 11. The access node arrangement according to item 10, wherein the RRC is configured to control the lower layer subnode to broadcast information identifying a network identity associated with any connected higher layer subnode.

[0157] Item 12. The access node arrangement according to item 10 or 11, wherein the RRC is configured to control random access signalling for the higher layer subnodes.

[0158] Item 13. The access node arrangement according to any preceding item, wherein the lower layer subnode is configured with a cell identity shared by the higher layer subnodes.

[0159] Item 14. The access node arrangement according to any preceding item, wherein each higher layer subnode comprises a radio link control, RLC, layer of a radio protocol stack.

[0160] Item 15. The access node arrangement according to item 14, wherein the split between the respective higher layer subnode and the lower layer subnode is configured between the RLC and a physical layer, PHY, of the radio protocol stack.

[0161] Item 16. The access node arrangement according to item 14, wherein the partitioning between a respective higher layer sub-node and a lower layer sub-node is configured between the RLC and the medium access control layer, MAC, of the radio protocol stack.

[0162] Item 17. The access node arrangement according to any of items 14 to 16, wherein each higher layer sub-node comprises at least the RLC of a central unit, CU, (CU_1, CU_M) and a distributed unit, DU, (DU_1, DU_M) of the access node arrangement.

[0163] Item 18. The access node arrangement according to any preceding item, comprising a plurality of central units, CUs, (CU_1, CU_M) and a plurality of distributed units, DUs, (DU_1, DU_M),

[0164] wherein the respective higher layer sub-node (300) implements:

[0165] one of the CUs (300A), and

[0166] a first layer DU part of one of the DUs (300B); and

[0167] wherein the lower layer sub-node (200) implements a second lower layer DU part common to the plurality of DU parts.

[0168] Item 19. The access node arrangement according to any preceding item, wherein the lower layer sub-node comprises an antenna interface (216C).

[0169] Item 20. A higher layer sub-node 300 for use in an access node arrangement (20) having a split layer functionality operating in a radio access network, the higher layer sub-node comprising:

[0170] an interface (316D) configured to provide a connection with one core network (CN-M);

[0171] logic circuitry (310) configured to implement a higher layer (313) of a radio protocol stack; and

[0172] a communication interface (Fx) configured for connection (200) with a lower layer sub-node configured to implement a lower layer (213) of the higher layer supporting in parallel a plurality of higher layer sub-nodes, wherein the higher layer sub-node uses the communication interface to obtain full support of the radio protocol stack, the lower layer sub-nodes comprising a radio unit (215) configured to communicate lower layer data,

[0173] wherein the higher layer child node is configured as a master child node and is configured to control a scheduler to manage allocation of downlink data transmissions from respective data buffers in any other higher layer child node connected with the lower layer child node.

[0174] Item 21. The higher layer child node according to item 20, further comprising:

[0175] a data buffer configured to provide data to the lower layer child node via the communication interface (Fx).

[0176] Item 22. The higher layer child node according to item 20, wherein the master child node does not comprise a data buffer.

[0177] Item 23. The higher layer child node according to any of items 20 to 22, wherein the master child node comprises the scheduler.

[0178] Item 24. The higher layer child node according to any of items 20 to 23, wherein the logic circuitry is configured to implement a radio link control, RLC, layer of a radio protocol stack.

[0179] Item 25. The higher layer child node according to any of items 20 to 24, wherein the scheduler is comprised in the lower layer child node, the higher layer child node further comprising:

[0180] a control interface (Fy) connected to the lower layer child node to transmit configuration and control signals to control resource allocation by the scheduler.

[0181] Item 26. The higher layer child node according to any of items 20 to 25, wherein the scheduler is configured to manage allocation dependent on core network association of the respective higher layer child node.

[0182] Item 27. The higher layer child node according to any of items 20 to 26, wherein the scheduler is configured to manage allocation with priority based on requesting core network.

[0183] Item 28. The higher layer child node according to any of items 20 to 27, wherein the logic circuitry implements a radio resource control layer, RRC (300C), configured to control broadcast signaling for any higher layer child node connected with the lower layer child node.

[0184] Item 29. The higher layer child node according to item 28, wherein the RRC is configured to control the lower layer child node to broadcast information identifying a network identity associated with any connected higher layer child node.

[0185] Item 30. The higher layer child node of item 28 or 29, further comprising:

[0186] an RRC interface (Fz) connected to the RRC layer (301C) of any higher layer child node connected with the lower layer child node.

[0187] Item 31. The higher layer child node of any one of items 28 to 30, wherein the RRC of the master child node is configured to control random access signaling to any higher layer child node connected with the lower layer child node.

[0188] Item 32. The higher layer child node of claim 31, wherein the RRC of the master child node is configured to:

[0189] in response to a random access request from a user equipment, UE, and

[0190] forward a subsequent message received from the UE indicating a network association to the RRC of the higher layer entity corresponding to the network association.

[0191] Item 33. A higher layer child node (300) for use in an access node arrangement (20) having split layer functionality operating in a radio access network, the higher layer child node comprising:

[0192] an interface (316D) configured to provide a connection with one core network (CN-1);

[0193] logic circuitry (310) configured to implement a higher layer (313) of a radio protocol stack;

[0194] a communication interface (Fx) configured for connection (200) with a lower layer child node configured to implement a lower layer (213) of a higher layer supporting a plurality of higher layer child nodes in parallel, wherein the higher layer child node uses the communication interface to obtain full support of the radio protocol stack, the lower layer child node comprising a radio unit (215) configured to communicate lower layer data; and

[0195] a data buffer configured to provide data to the lower layer child node through the communication interface (Fx),

[0196] an interface to a scheduler that controls the scheduler to manage allocation of downlink data transmissions from at least the data buffer under control of other higher layer child nodes operating as master child nodes, wherein the higher layer child node is configured as a slave child node of the master child nodes.

[0197] Item 34. The higher-layer child node of item 33, configured to transmit data from the data buffer over the communication interface in accordance with a resource allocation determined by the scheduler.

[0198] Item 35. A lower-layer child node (200) of an access node arrangement (20) with split-layer functionality for operation in a radio access network, the lower-layer child node comprising:

[0199] a radio unit (215);

[0200] a communication interface (Fx) configured to provide a parallel connection with a plurality of higher-layer child nodes (300, 301) of the access node arrangement, the higher-layer child nodes each configured to implement higher layers of a radio protocol stack for an individual core network connection;

[0201] a logic circuitry (210) configured to implement lower layers (213) of a radio protocol stack supporting the higher layers of the at least two higher-layer child nodes (300, 301) and to use the radio unit (215) for transmitting lower-layer data;

[0202] wherein the lower-layer child node is configured to receive data from respective data buffers in any connected higher-layer child node for transmission by the radio unit in accordance with a resource allocation determined by the scheduler.

[0203] Item 36. The lower-layer child node of item 35, wherein the scheduler is comprised in a single higher-layer child node operating as a master child node.

[0204] Item 37. The lower-layer child node of item 35, comprising the scheduler.

[0205] Item 38. The lower-layer child node of item 37, comprising:

[0206] a control interface (Fy) connected to the single higher-layer child node operating as a master child node, wherein the control interface is configured for obtaining configuration and control signals for controlling the resource allocation by the scheduler for the any connected higher-layer child node.

[0207] Item 39. The lower-layer child node of any of items 35 to 38, wherein the scheduler is configured to manage the allocation in dependence of core network associations of the connected higher-layer child nodes.

[0208] Item 40: The lower-layer child node of any of items 35 to 40, wherein the scheduler is configured to manage the allocation of downlink data transmissions from respective data buffers in the connected higher-layer child nodes.

Claims

1. An access node arrangement (20) with split-layer functionality for operation in a radio access network, the access node arrangement comprising: at least two higher-layer sub-nodes (300, 301), wherein each higher-layer sub-node is configured to implement a higher layer (313) of a radio protocol stack for an individual core network connection; a lower-layer sub-node (200) comprising a radio unit (215) and a communication interface (Fx) for a parallel connection with the higher-layer sub-nodes, and configured to implement a lower layer (213) supporting the higher layer of the higher-layer sub-nodes (300, 301), and to transmit lower-layer data using the radio unit (215), whereby each higher-layer sub-node (300, 301) obtains full support of the radio protocol stack; and a scheduler (214, 315) configured to manage allocation of radio resources for a respective higher-layer sub-node, wherein the scheduler is configured to manage allocation of downlink data transmission from respective data buffers in the higher-layer sub-nodes.

2. The access node arrangement according to claim 1, wherein, The higher-layer sub-nodes are associated with separate core networks.

3. The access node arrangement according to claim 1 or 2, wherein, The scheduler (214) is comprised in one of the higher-layer sub-nodes (300).

4. The access node arrangement according to claim 1 or 2, wherein, The scheduler (214) is comprised in the lower-layer sub-node.

5. An access node arrangement according to any preceding claim, wherein, The scheduler is configured to manage allocation dependent on core network association of a respective higher-layer sub-node.

6. An access node arrangement according to any preceding claim, wherein, The scheduler is configured to manage allocation based on a requesting core network with a priority.

7. An access node arrangement according to any preceding claim, wherein, One of the higher-layer sub-nodes is a master sub-node configured to control signalling for the higher-layer sub-nodes.

8. The access node arrangement according to claim 7, wherein, The master sub-node is configured to control the scheduler to manage allocation for the higher-layer sub-nodes.

9. The access node arrangement according to claim 7 or 8, wherein, The master sub-node does not comprise a data buffer.

10. A higher-layer sub-node (300) for use in an access node arrangement (20) with split-layer functionality for operation in a radio access network, the higher-layer sub-node comprising: an interface (316D) configured to provide a connection with one core network (CN-M); logic circuitry (310) configured to implement a higher layer (313) of a radio protocol stack; and a communication interface (Fx) configured for connection with a lower-layer sub-node (200) configured to implement a lower layer (213) supporting the higher layer of multiple higher-layer sub-nodes in parallel, wherein the higher-layer sub-node obtains full support of the radio protocol stack using the communication interface, the lower-layer sub-node comprising a radio unit (215) configured to transmit lower-layer data, wherein the higher-layer sub-node is configured as a master sub-node and configured to control a scheduler to manage allocation of downlink data transmission from respective data buffers in any other higher-layer sub-node connected with the lower-layer sub-node.

11. The higher-layer sub-node of claim 10, further comprising: a data buffer configured to provide data to the lower layer child node through the communication interface (Fx).

12. The higher layer child node of claim 10, wherein, The master child node does not comprise a data buffer.

13. The higher layer child node of any of claims 10 to 12, wherein, The master child node comprises the scheduler.

14. The higher layer child node of any of claims 10 to 13, wherein, The scheduler is comprised in the lower layer child node, the higher layer child node further comprising: a control interface (Fy) connected to the lower layer child node to transmit configuration and control signals to control resource allocation by the scheduler.

15. The higher layer child node of any of claims 10 to 14, wherein, The scheduler is configured to manage allocation depending on core network association of the respective higher layer child node.

16. The higher layer child node of any of claims 10 to 15, wherein, The scheduler is configured to manage allocation based on requested core network utilization priority.

17. A higher layer child node (300) for use in an access node arrangement (20) with split layer functionality operating in a radio access network, the higher layer child node comprising: an interface (316D) configured to provide connectivity to one core network (CN-1); logic circuitry (310) configured to implement a higher layer (313) of a radio protocol stack; a communication interface (Fx) configured for connectivity with a lower layer child node (200) configured to implement a lower layer (213) of the higher layer supporting multiple higher layer child nodes in parallel, wherein the higher layer child node uses the communication interface to obtain full support of the radio protocol stack, the lower layer child node comprising a radio unit (215) configured to communicate lower layer data; and a data buffer configured to provide data to the lower layer child node through the communication interface (Fx), an interface to a scheduler, the interface controlling the scheduler to manage allocation of downlink data transmission from at least the data buffer under control of another higher layer child node operating as a master child node, wherein the higher layer child node is configured as a slave child node of the master child node.

18. The higher layer child node of claim 17, configured to transmit data from the data buffer through the communication interface according to resource allocation determined by the scheduler.

19. A lower layer child node (200) for use in an access node arrangement (20) with split layer functionality operating in a radio access network, the lower layer child node comprising: a radio unit (215); a communication interface (Fx) configured to provide parallel connectivity with multiple higher layer child nodes (300, 301) of the access node arrangement, the higher layer child nodes each configured to implement a higher layer of a radio protocol stack for an individual core network connection; logic circuitry (210) configured to implement a lower layer (213) of the radio protocol stack supporting the higher layer of at least two higher layer child nodes (300, 301) and to communicate lower layer data using the radio unit (215); wherein the lower layer sub-nodes are configured to receive data from respective data buffers in any of the connected higher layer sub-nodes for transmission by the radio unit according to resource allocation determined by a scheduler.

20. The lower tier child node of claim 19, wherein, The scheduler is comprised in a single higher layer sub-node operating as a master sub-node.

21. The lower layer sub-node according to claim 19, comprising the scheduler.

22. The lower layer sub-node according to claim 21, comprising: a control interface (Fy) connected to a single higher layer sub-node operating as a master sub-node, wherein the control interface is configured for obtaining configuration and control signals for controlling resource allocation by the scheduler for the any of the connected higher layer sub-nodes.

23. The lower tier child node of any of claims 19-22, wherein, The scheduler is configured to manage allocation dependent on core network association of the connected higher layer sub-nodes.

24. The lower tier child node of any one of claims 19 to 23, wherein, The scheduler is configured to manage allocation of downlink data transmission from respective data buffers in the connected higher layer sub-nodes. The scheduler is configured to manage allocation of downlink data transmission from respective data buffers in the connected higher layer sub-nodes.

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