Radio nodes for radio access networks and methods

Abstract

A method of operating a first radio node to control a second radio node, which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network. The first radio node may include functions of a CU and a DU, so that there is no standardised interface between the CU and the DU. The second radio node may include physical layer functions including transceiver circuitry for transmitting or receiving, so that in combination the first radio node and the second radio node form a base station, access node or gNB of a radio access network of a wireless communications network. The method comprises transmitting, via a wired or point to point wireless interface between the first radio node and another first radio node, control information for supporting transmission and / or reception of radio signals via a wireless access interface by the one or more communications devices or receiving the control information from the other first radio node via the interface, or controlling the second radio node to transmit the control information to another second radio node via a wireless over-the-air, OTA, interface between the second radio node and the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface, which may be a point to multipoint interface. By providing a wireless OTA interface between second radio nodes of adjacent cells for example, in addition to an interface between first radio nodes which are controlling the second radio nodes, control information can be communicated between first radio nodes via the interface or the second radio nodes via the wireless OTA interface.

Description

[0001] RADIO NODES FOR RADIO ACCESS NETWORKS AND METHODS BACKGROUND

[0002] Field of Disclosure

[0003] The present disclosure relates to methods of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network. The present disclosure also relates to radio access nodes and radio access networks.

[0004] The present disclosure claims the Paris convention priority to European patent application EP25152639.8 filed on 17 January 2025, the content of which is incorporated herein by reference in its entirety.

[0005] Description of Related Art

[0006] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

[0007] Wireless communications networks can be generally thought of as a core network part and a radio network part. The radio network part includes radio access nodes which are generally referred to as base stations. As different applications and services evolve to support an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems, there is a need to involve correspondingly radio access networks to service this evolution. For example, it is expected future wireless communications networks will be expected efficiently to support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different consideration may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

[0008] In view of this there is expected to be a desire for future wireless communications networks to have a radio network part comprising radio access nodes such as base stations with improved capabilities in order to meet the requirements of future services and devices such as that which evolves from a 5G or new radio (NR) systems / new radio access technology (RAT) systems.

[0009] SUMMARY OF THE DISCEOSURE

[0010] The present disclosure can help address or mitigate at least some of the issues discussed above.Embodiments of the present technique can provide a method of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network. The first radio node may include functions of a CU and a DU, so that there is no standardised interface between the CU and the DU. The second radio node may include physical layer functions including transceiver circuitry for transmitting or receiving, so that in combination the first radio node and the second radio node form a base station, access node or gNB of a radio access network of a wireless communications network. The method comprises controlling the second radio node to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices. The method comprises either transmitting, via a wired or point to point wireless interface between the first radio node and another first radio node, control information for supporting the transmission and / or the reception of the radio signals via the wireless access interface by the one or more communications devices or receiving the control information from the other first radio node via the interface, or controlling the second radio node to transmit the control information to another second radio node via a wireless over-the-air, OTA, interface between the second radio node and the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface, which may be a point to multipoint interface. By providing a wireless OTA interface between second radio nodes of adjacent cells for example, in addition to an interface between first radio nodes which are controlling the second radio nodes, the first radio nodes can determine whether control information associated with a radio control function for example should be communicated between first radio nodes via the wired interface or the second radio nodes via the wireless OTA interface. The interface between first radio nodes may be an Xninterface, which may be a wired or wireless point to point interface.

[0011] Embodiments of the present technique can also provide a method of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network. The method comprises transmitting control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via an interface between a first radio node and another first radio node or receiving the control information from the other first radio node via the wired interface, the control information comprising a plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, and controlling the second radio node to transmit one or more indices indicating a selected value for one or more of the parameters via the wireless over-the-air, OTA, interface to the other second radio node or controlling the second radio node to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface, the one or indices indicating the selected value of the one or more parameters for the radio control function. By transmitting the plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, such as in a form of a table or mapping arrangement, only an index needs to be transmitted via the wireless OTA interface to identify the parameter which improves security and reduces a time for communicating the parameter.

[0012] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

[0014] Figure 1 schematically represents a wireless communications network illustrating architectural components which a radio access network part according new radio access technology (RAT) or 5G; Figure 2 is a schematic block diagram of parts forming a communications system of the wireless communications network of Figure 1 and which may also for part of certain embodiments of the present disclosure;

[0015] Figure 3A is a representation of a gNB DU and a gNB CU communicating via an Fl interface; Figure 3B is a schematic representation of a protocol stack operated respectively by the gNB DU and gNB CU shown in Figure 3A for communicating control plane data; and Figure 3C is a schematic representation of a protocol stack operated respectively by the gNB DU and gNB CU shown in Figure 3A for communicating user plane data;

[0016] Figure 4a schematically represents elements of a wireless communications system according to NR / 5G which are used to form a radio bearer for a communications device / UE, which include a virtual CU, a shared DU connected via a TRP, which forms a wireless access interface with the communications device / UE; and Figure 4b schematically represents functions of a protocol stack for each of the elements shown in Figure 4a and which includes an additional security measure to encrypt data at certain protocol layers according to a technique disclosed in EP21155607.1;

[0017] Figure 5 schematically represents functions forming part of protocol stack for a control plane within a control unit (CU-CP) and a user plane within a control unit (CU-UP) and a distributed unit (DU) when communicating with two communications devices / UEs, in which an adaptation is made to distribute some protocol functions between the CU and the DU;

[0018] Figure 6a schematically represents elements of a wireless communications system which are used to form a radio bearer for a communications device / UE according to example embodiments of the present technique, which include a combined CU and DU connected to a radio unit, which forms a wireless access interface with the communications device / UE; and Figure 6b schematically represents functions of a protocol stack for each of the elements shown in Figure 6a according to example embodiments;

[0019] Figure 7 is a schematic representation of a wireless communications network which includes a radio network part formed from radio network infrastructure equipment which include first radio nodes which include functions of a CU and DU of the wireless communications networks of Figures 1 to 5, and the second radio nodes which transmit and receive radio signals according to a wireless access interface provided by the radio access network according to example embodiments;

[0020] Figure 8 is a schematic representation of a parts of the wireless communications network shown in Figure 7 which illustrate a wireless interface forming an over-the-air (OTA) communications facility between second radio nodes, and an interface (Xntype) between the first radio nodes according example embodiments;

[0021] Figure 9 is an example message flow diagram illustrating a process in which communications parameters and / or information are exchanged via either the wireless interface (OTA) of second radio nodes or the interface between first radio nodes according to an example embodiment;

[0022] Figure 10 is a schematic flow diagram illustrating a process in which information, parameters and operations are performed to control radio communications by communicating different parameters and information via either the interface between first radio nodes or the wireless / OTA interface between the second radio nodes of a radio access network according to example embodiments; andFigure 11 is an example message flow diagram illustrating a process in which communications parameters and / or information are exchanged via a wireless interface (OTA) of second radio nodes and an interface between first radio nodes according to another example embodiment.

[0023] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] As explained above, embodiments of the present technique can provide arrangements in which functionality of a gNB or base station are improved in order to support wireless communications between communications devices more efficiently. More particularly, embodiments provide enhancement to a 5G architecture, which may find application with other generations of a radio access network part of a mobile wireless communications system such as 6G. In order to get a better appreciation of advantages and aspects of the present technology, a more detailed description will be provided of current techniques using 5G technology.

[0025] New Radio Access Technology (5G)

[0026] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 1. In Figure 1 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 40 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 40 are connected to a central unit (CU) 44 (which may be referred to as a controlling node) via an interface 46. The central unit 44 is then connected to the core network 20 via a connection interface 60, which may contain all other functions required to transmit data for communicating to and from the wireless communications devices or user equipment 14 and the core network 20 may be connected to other networks.

[0027] As will be appreciated by those acquainted with the wireless communications network according to 5G standard shown in Figure 1, the CU 44, DU 40 and TRPs 10 collectively perform functions which are conventionally performed by a network base station or, in accordance with 5G terminology, a gNB. According to the 5G architecture and a split of functions between the CU 44 and the DU 40, the terms CU and DU may be respectively referred to as a “gNB-CU” and a “gNB-DU” when it is appropriate to emphasise that the CU and the DU form part of a gNB. Similarly, the TRPs 10 of Figure 1 may in part have a corresponding functionality to a base station or eNodeB of an LTE network.

[0028] Also shown in Figure 1 and pertinent to the present technology is an interface 64 between CU’s 44. This interface 64 is known as the Xninterface and was introduced as part of 4G / LTE for gNB used to communicate with each other for example to exchange signalling information in respect of handover between UEs because typically the gNB’s using the Xninterface will be neighbouring cells. The present technology envisages the presence of an Xninterface between gNB functionality for future networks. The communications devices 14 may be referred to mobile terminals, terminals or user equipment (UE), which encompasses chip sets and have a functionality corresponding to the UE devices known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE, 5G or other known variations and releases of these mobile telecommunications standards.As explained in more detail below, depending on the application, the responsibility for scheduling transmissions on the radio interface between the respective DUs 44 and the communications devices 14 may lie with the controlling node / central unit (CU) and / or the distributed units (DU) / TRPs. A communications device 14 is represented in Figure 1 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with a CU 44 in one cell 12 via one of the distributed units 40 / TRPs 10 associated with the cell 12.

[0029] Figure 2 provides detail of some of the components of the network shown in Figure 1. In Figure 2, a TRP 10 as shown in Figure 1 comprises, as a simplified representation, a wireless transmitter circuitry 30, a wireless receiver circuitry 72 and a controller or controlling processor 74 which may operate to control the transmitter circuitry 30 and the wireless receiver circuitry 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 2, an example communications device 14 (such as a UE) is shown to include a corresponding transmitter circuitry 76, a receiver circuitry 78 and a controller circuitry 80 which is configured to control the transmitter circuitry 76 and the receiver circuitry 78 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter circuitry 70 and received by the receiver circuitry 72 in accordance with the conventional operation.

[0030] The transmitter circuitry 70, 76 and the receiver circuitry 72, 78 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency filters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G / NR standard. The controller processor / circuitry 74, 80 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 2 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

[0031] As shown in Figure 2, the TRP 10 also includes a network interface, which connects to the DU 42 via a physical interface 16 to provide a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 44 to the core network 20.

[0032] The interface 46 between the DU 40 and the CU 44 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with specifications [1] and [2], and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 and the connection between the interface of the TRP 10 to the DU 40 and the Fl interface 46 from the DU 40 to the CU 44.As will be appreciated by those acquainted with 5G architecture, the CU 44 is a logical node which hosts Radio Resource Control (RRC) protocols, Service Data Adaptation Protocols (SDAP) and Packet Data Convergence Protocols (PDCP) of a gNB. The CU 44 partly controls the operation of one or more DUs 40 and terminates the Fl interface 46 for the DUs that it controls. The DU 40 is a logical node which hosts Radio Uink Control (RLC), Medium Access Control (MAC) and Physical (PHY) layers of a gNB or en-gNB. The operation of the DU 40 is partly controlled by the CU 44 for which the DU 40 terminates the Fl interface 46.

[0033] Although not shown in Figures 1 or 2, it will be familiar to those acquainted with 5G architecture that the CU 44 may be further split into a CU-CP which performs the control plane functions of the CU 44 and a CU-UP which performs the user plane functions of the CU 44 (see for example, [3]). In more detail, the CU-CP is a logical node hosting an RRC protocol and a control plane part of a PDCP protocol of the CU 40 for the gNB or en-gNB. The CU-CP terminates an El interface connected with the CU-UP and an Fl-C interface connected with the DU 40. As will be appreciated, the Fl-C interface carries control plane signalling of the Fl interface 46.

[0034] The CU-UP is a logical node, which hosts a user plane part of a PDCP protocol of the CU 40 for an en-gNB. Alternatively, the CU-UP is a logical node, which hosts a user plane part of the PDCP protocol and an SDAP protocol of the CU 44 for a gNB. The CU-UP terminates an El interface connected with the CU-CP and an Fl-U interface connected with the DU 40. As will be appreciated, the Fl-U interface carries user plane signalling of the Fl interface 46.

[0035] In order to appreciate example embodiments, a protocol stack for forming a conventional Fl interface shown in Figure 1 and 2 will be explained with reference to Figure 3.

[0036] In respect of a protocol stack, Figures 3a, 3b and 3c provide an illustration of processing performed by the elements shown in Figures 1 and 2 which form the packet data communications path 46 between the gNB-DU 40 and the gNB-CU 44 via the Fl interface 46. Control plane communications are considered separately to user plane data although in practice they form the same interface and are processed and transmitted by the same hardware equipment. As shown in Figure 3A communication is formed between the gNB DU 40 and a gNB CU 44 for the Fl interface 46. However, the control plane protocol stack to form this interface is shown in Figure 3B, and the user plane protocol stack for communicating the user data between the gNB-CU 44 and gNB-DU 40 is shown in Figure 3C. As shown in Figure 3B at the radio network layer, the control plane is formed by Fl Application Protocols (APs) 301a in the gNB-CU 44 and by Fl APs 301b in the gNB DU 40. As will be understood by those acquainted with the 5G Architecture, communication between a gNB-CU and a gNB DU is by IPv6 or IPv4 Internet protocols as specified in [4], This is shown in Figure 3B as an IP layer 302a in the gNB-CU 40 and an IP layer 302b in the gNB-DU 42 forming an IP communication interface 302c. A Stream Control Transmission Protocol (SCTP) layer of the protocol stack 304a, 304b, 304c controls end to end communication via the IP layer 302 including flow control and quality of service. The IP data is communicated between the gNB DU and gNB CU via logical data link layer 306a, 306b, 306c and the physical layer 308a, 308b, 308c.

[0037] In the user plane, the radio network layer is formed by RLC layer 320a, 320b to form the Fl interface for communicating use plane data 46. The protocol stack in the transport layer comprises a GPRS Tunnelling Protocol for user plane data (GTP-U) 322a, 322b, 322c, which controls communication of user plane data for roaming and home subscribers via a UDP layer 324a, 324b, 324c which controls communication of user plane data via an IP layer 326a, 326b, 326c. As with the control plane, the IP data is communicated between the gNB DU and gNB CU via logical data link layer 328a, 328b, 328c and the physical layer 330a, 330b, 330c.Functionally respective layers in the CU and the DU for both the control plane and the user plane may be collectively referred to as a transport network layer 350a, 350b and radio network layer 352a, 352b respectively, which are typically represented together.

[0038] CU-DU Split Functions

[0039] As indicated above, the CU 40 and DU 42 are configured to execute gNB functionality. The allocation or splitting of gNB functions between the CU 40 and the DU 42 is discussed in [5], [6] and [7], Further Developments of Radio Network Architecture

[0040] As indicated above, the present technology concerns enhancement of the radio network architecture of a wireless communications network such as those which may be deployed in a 6G or further generations of wireless communications networks. As observed in our co-pending European patent application number EP21155607.1 a CU may be deployed with a plurality of DUs, (as shown in Figure 1), which may be operating to serve separate networks and may be deployed from different operators. That is to say, a mobile network operator (MNO) may wish to procure services from different entities which may themselves acquire network components from different sources / operators / implementers.

[0041] One proposal for a new architecture is to remove the CU - DU split. This may be achieved by not specifying the interface between CUs and DUs as it is currently specified to form the Fl interface, although the CU and DU functionality may be the same or similar to that which is currently proposed for 5G. This is because there are some issues with splitting the architecture of the functionality performed by the CU and DU and standardising the interface between the CU and the DU, which may have some disadvantages. For example, as identified in our co-pending European patent application number EP21155607.1 filed 5 February 2021, the contents of which are incorporated herein by reference, a vertical stack which requires a split of the DU may create some security problems. It was envisaged that the CU and DU spits may result in the virtualised CU and DU being hosted physically by different service providers and hence our co-pending European patent application EP21155607.1 provided a new security in that if there is a DU, which is hosted separately for a common CU, then some proprietary protocol aspects such as radio resource management performed by the CU may be open to an operator of a different mobile network or infrastructure equipment, and therefore security may be compromised.

[0042] According to this example, security is introduced for MAC and physical layer signalling at the DU as illustrated by the diagram of Figures 4a and 4b. This technology is explained in more detail in EP21155607.1. However, to appreciate advantages and improvements provided by example embodiments of the present technique, a brief explanation is provided below.

[0043] Figure 4a represents some components of a radio access network, which are configured to form a connection with a communications device / UE. That is to say that these components operate to support a radio bearer across the radio access network to the UE. As shown in Figure 4a, a virtual CU 44 is connected to a shared DU, which is connected to a TRP 10. The TRP 10 forms provides a wireless access interface for transmitting and receiving data to a UE 14. Figure 4b shows these components in more detail in respect of the functions of a protocol stack as these are implemented in each of these components.

[0044] As shown in Figure 4b, a scheduler 462 along with algorithms which provide a function for Radio Resource Management (RRM) can be considered as the “brain” of a base station or radio network access node. The scheduler 462 is normally one of the main distinguishing factors between the offerings from different network vendors and operators. However, if the scheduler or RRM algorithms of a base station are shared with another operator or service provider then the operators may lose their competitiveadvantage. In respect of a protocol stack, Figure 4b provides an illustration of processing performed by the elements shown in Figures 3b and 3c which form the packet data communications path (radio bearer) 400 to and from the UE 14. As will be understood by those acquainted with the 5G Architecture, PDCP is a sublayer 402a, 402b in the protocol stack for communicating data between entities which receives / transmits network layer traffic (TCP / IP traffic). A Data Radio Bearer (DRB) is a logical connection used inside a 5G protocol stack to carry data packet data units (PDUs). A Service Data Adaptation Protocol (SDAP) 404a, 404b, maps a quality of service (QoS) flow to and from a DRB at the PDCP sublayer 402a, 402b, in both downlink and uplink directions. As shown in Figure 4 therefore SDAP entities 404a, 404b in the UE 14 and the CU 44 respectively form an SDAP layer supported PDCP entities 402a, 402b forming the PDCP layer. Both the SDAP and the PDCP layers 404, 402 communicate data at these layers between the UE 14 and the CU 44. These layers 404, 402 are supported by operations of the TRP 10 and the DU 40. A transport layer 350a, 350b is formed by transport processors between the Shared DU 40 and the CU 44.

[0045] A radio link control (RLC) layer 406a, 406b controls communication via the radio link 406 between the shared DU 40 and the UE 14, which is supported by a MAC sub-layer 408a, 408b. Data is communicated using the RLC and MAC sub-layers 406, 408 via a physical (PHY) layer 410a, 410b, 410c and a transport layer 412a, 412b formed in the shared DU 40 and the TRP 10 as a wired connection 415 and between the TRP 10 and the UE 14 as a radio connection 410 according to established techniques of for example a 5G radio access network.

[0046] As will be appreciated the TRP 10 includes a RRH as mentioned above and therefore includes antennas forming a part of the PHY layer 410 to transmit / receive RF signals and the rest of PHY layer including baseband processing, resource allocation etc. will be implemented in the DU 40. Transport between the TRP 10 and the shared DU 40 could be based on traditional interfaces like CPRI or e-CPRI or ethemet or similar. The RLC sub-layer 406, MAC sub-layer 408, and part of the PHY layer 410, the scheduler, and the RRM algorithms therefore virtually reside in the DU 40. The PDCP 404 and the SDAP 402 entities reside in the CU 44 and the UE 14.

[0047] In order to obviate a security problem for proprietary information associated with RRM messages produced by the scheduler 462 caused by the CU - DU split the technique disclosed in EP proposes that the baseband processing forming the elements of the protocol stack in the shared DU 40, which form a gNB with the TRP 10 are encrypted as represented by a shaded box 460. That is to say that all of the processing / processors forming the RLC sublayer 406b, the MAC sublayer 408b and the PHY layer 412b are encrypted, although note that the transport layer 412b may have its own encryption and 3GPP does not define transport. Correspondingly in the TRP 10, the PHY layer de-crypt messages and data received from the PHY layer 412a, 412b and the transport layer 415, and between the physical layer 410a, 410b as represented by a shaded box 470. Optionally therefore PDUs communicated between the TRP 10 may be encrypted according a security tunnel 470, which may be implemented for example using IPSec.

[0048] Furthermore, encryption or ciphering may be performed at the PHY layer 410 between the TRP 10 and the UE 14 as represented by a security tunnel 470.

[0049] According to the example illustrated by Figures 4a and 4b, encryption of the functions shown serves to secure sensitive information whilst allowing processes according to a protocol stack which may be used to implement functions of a gNB to be hosted on another operator’s or networks infrastructure equipment such as a DU. However, the need to encrypt these functions results from a split of the CU DU architecture. More generally an infrastructure equipment of a radio access network may be shared between network operators. Processors or processing which provides functions of a scheduler of RRM algorithms may be hosted on a shared infrastructure equipment. Accordingly, the encryption of thephysical and transport layer 470 is required because of the split of the architecture between the DU and the CU for a radio access base station of the radio access network.

[0050] A similar technique, which mitigates a problem of the CU - DU split is disclosed in European patent application number EP22165697.8 fded on 30 March 2022, the contents of which are incorporated herein by reference in their entirety. The technique disclosed in EP22165697.8, also addresses a technical disadvantage of a CU - DU split. According to this arrangement communication between neighbouring TRPs is proposed in order to coordinate radio resource management and interference mitigation in a radio access network. Figure 5 provides an example illustration of this technique with more detail found in EP22165697.8.

[0051] Figure 5 schematically illustrates a proposed allocation of gNB functions in a CU and a DU for a plurality of UEs showing corresponding functions to those of Figure 5. As shown in Figure 5, a CU-CP 514 is configured to perform a set of functions including RRM-1 functions 502, RRC-1 functions 503, PDCP-CP functions 504, Security- 1 functions 506, NAS functions 508, UE context functions 510 and QoS functions 512. A CU-UP 518 is configured to perform PDCP-UP functions 516. A DU is configured to perform a set of functions RRM-2 functions 520, RRC-2 functions 522, Security-2 functions 524, RLC functions 526, MAC functions 528 and PHY functions 530. The RRM-1 functions 502 and the RRM-2 functions 520 may each represent a sub-set of the RRM functions 402 in CU-CP 40a. In other words, the RRM functions 502 are split into RRM-1 functions 502 and the RRM-2 functions 520, with the RRM-1 functions 502 being performed by the CU-CP 514 and the RRM-2 functions 520 being performed by the DU 532. Similarly, the RRC-1 functions 503 and the RRC-2 functions 522 may each represent a sub-set of the RRC functions 403 in CU-CP 40a. In other words, the RRC functions 403 are split into RRC-1 functions 503 and the RRC-2 functions 522, with the RRC-1 functions 503 being performed by the CU-CP 514 and the RRC-2 functions 522 being performed by the DU 532. Similarly, the Security- 1 functions 506 and the Security-2 functions 524 may each represent a sub-set of the Security functions in the CU-CP 44a. In other words, the Security functions are split into the Security- 1 functions 506 and the Security-2 functions 524, with the Security-1 functions 506 being performed by the CU-CP 514 and the Security-2 functions 524 being performed by the DU 532.

[0052] The splitting of RRM functions between the CU-CP 514 and the DU 532 can enable a more efficient management of communications resources. The splitting of RRC functions CU-CP 514 and the DU 532 may enable reduced latency communications by reducing message exchanges between the CU-CP 514 and the DU 532. The splitting of security functions between the CU-CP 514 and the DU 532 can provide improved security communications between the CU-CP 514 and the DU 532, or between two DUs over an air interface.

[0053] The NAS functions 508, the UE context functions 510 and the QoS functions 512 performed by the CU-CP-514 may broadly correspond to the NAS functions 408, the UE context functions 410 and the QoS functions 412 performed by the CU-CP 40a. The PDCP-UP functions 516 in the CU-UP 518 may broadly correspond to the PDCP functions-UP 414 in the CU-UP 40b. The RLC functions 526, the MAC functions 528 and the PHY functions 530 performed by the DU 532 may broadly correspond to the RLC functions 416, the MAC functions 418 and the PHY functions 420 performed by the DU 42.

[0054] As will be appreciated, the above allocation of gNB functions among the CU-CP 514 and the DU 532 provides a delegation of at least some CU functionality to a DU. The delegation of RRC functions to a DU may reduce the number of exchanges between a CU and a DU required to control communications with a communications device such as when a configuration change is required.Although the above has been described for the transmission of a downlink control message from the CU-CP 514 to a UE, example embodiments can be applied to an uplink control message transmitted from the UE to the CU-CP 514. For example, the DU 532 may receive a control message from the UE for transmission to the CU-CP 514. In one example, the control message may include an RRC message such as a measurement report. The DU 532 may execute the RRC -2 functions 522 based on the RRC message to extract a part of the RRC message. Based on the extracted part of the RRC message, the DU 532 may determine that it can respond to the UE directly. For example, the DU 532 may prepare a configuration (such as a measurement configuration) based on the control message and transmit the configuration to the UE or use this information in RRM-2 522 or exchange this information with another DU 542. The DU 532 may determine that the control message should be forwarded to the CU for the CU to extract a remaining part of the RRC message. In some embodiments, the DU 532 may transmit the configuration to the UE and forward the control message to the CU. Upon receiving the control message, the CU may extract a remaining part of the RRC message from the control message. Based on the extracted remaining part of the RRC message, the CU may decide to change a configuration (such as a measurement configuration) of the UE based on the extracted remaining part of the message. When the CU changes a configuration of the UE, the process may follow the same steps as explained above for the transmission of the control message from the CU to the UE.

[0055] Figure 5 illustrates a set of functions for a first communications device 540 in the CU-CP 514, the CU-UP 518 and a first DU 532a. Furthermore, Figure 5 illustrates a set of functions for a second communications device 542 in the CU-CP 514, the CU-UP 518 and a second DU 532b.

[0056] The first DU 540 and the second DU 542 may be physically separate nodes. As such, there is provided between the first DU 532a and the second DU 532b an air interface 550 configured for the exchange of information for interference management. The air interface may utilise communications resources of the physical layer. In other words, communications resources are shared between the first communications device 540, the second communications device 542, the first DU 532a and the second DU 532b. The first communications device 540 may be located in a cell provided by the first DU 532a and the second communications device is located in a cell provided by the second DU 532b. In other words, the first DU 532a is configured to control the first communications device 540 and the second DU 532b is configured to control the second communications device 542?. Therefore, if any communications resource management is required to manage inter-cell interference between the cell containing the first communications device 540 and the cell containing the second communications device 542, such information can be exchanged over the air interface 550 between the first DU 532a and the second DU 532b. In the example shown in Figure 5, the first DU 532a and the second DU 532a are physically separate nodes. Therefore, the air interface 550 may be referred to as a “physical DU-DU interface”. Alternatively, due to the presence of the RRM-2 functions 520, the RRC -2 functions 522 and the Security functions 524 in the first DU 532a and the second DU 532b, the air interface 550 may be referred to as a “logical CU-CU interface”. In other words, the air interface 550 may be regarded as a logical CU-CU interface due to the presence of CU functions in the first DU 532a and the second DU 532b.

[0057] The configuration described in Figure 5 can improve interference management, particularly in the context of dense cell deployment. For example, the RRM-2 functions 522 may include measurement and reporting functions. Accordingly, the first DU 532a and the second DU 532b may utilise the RRM-2 functions 520 to respectively collect a measurement report from the first communications device 540 and the second communications device 542 respectively. Then, by exchanging information about the measurement reports over the air interface 550, the first DU 532a and the second DU 532b can determine whether additional measurement configurations are required for interference management and in addition if any action is required based on received measurement reports. Therefore, the provision of a RRCfunctions in a DU can reduce latency in communications for controlling a communications device compared with conventional architectures as explained above. Furthermore, the CU-CP 514 may execute the RRM-1 functions 502 and the DU 532 may execute the RRM-2 functions 520. The execution of the RRM functions 502, 520 may impact the contents of the RRC message based on, for example, an interference management / communications resource management decision. Furthermore, the CU-CP 514 may execute the Security-1 functions 506 and the DU 532 may execute the Security-2 functions 524 to provide for a secure transmission of the RRC message.

[0058] Improved Radio Network Architecture

[0059] With the above-mentioned disadvantages of the CU-DU split, it has been proposed for future radio access networks that there should not be a CU-DU standardised interface (Fl). Instead, it has been proposed that there should be a split between remote radio head (RRH) or Radio Unit (RU) and the rest of the gNB functionality, so that mobile network operators will still require multi-vendor deployments. Here, the RRH or RU can be a component of a device which has a functionality of the TRP(s). The RRH or RU disclosed herein can be also denoted as Remote Radio Unit (RRU), Remote Unit (RU), Edge Unit (EU). Figures 6a and 6b illustrate an example of functions with examples of a 5G / NR architecture explained above reference to Figures 1 to 5 adapted to remove a split CU-DU architecture to a new architecture where CU-DU split is not specified.

[0060] Figures 6a and 6b provides a corresponding presentation of radio network architectural components to the example shown in Figures 4a and 4b and so the same parts have corresponding numerical designations. As shown in Figure 4b, gNB functionality is formed as from a CU, a DU and a TRP which may include an RRH. In contrast, in Figure 6b, the gNB functionality without radio communication transmission and reception functions is formed as a unit 602, in which there is no split between the DU 604 and the CU 606 within this unit 602. Although functionality of a CU and a DU is still be present in the gNB, the interface between the CU 606 and the DU 604 is not specified and therefore may vary between implementations. As shown in Figure 6b, the CU 606 and the DU 604 represent respective functionalities of a CU and a DU. However, these are contained within the unit 602 which forms functional processing of a gNB but does not include transmission and / or reception of radio signals via a wireless access interface. Transmission and reception of radio signals forming a wireless access interface provided by the radio access network are made by physical components in a RRH or Radio Unit (RU) 600.

[0061] In the following explanation, the term first radio node is used to refer to functionality contained within a protocol stack and processing elements shown in Figures 6a and 6b which form the CU 606 and DU 604 functionality. The unit 602 is therefore referred to as a first radio node 602 whereas the RRH or RU 600 will be referred to as a second radio node. As will be appreciated, terminology used in respect of infrastructure equipment forming a radio access networks has varied between generations of wireless communications technologies so that the term base station was used for 2G, a NodeB was used for 3G, whereas an eNodeB was used in a 4G, which became a gNB for 5G. The infrastructure equipment forming a radio access networks in 6G can be denoted as 6G Node B or 6G RAN node. Hence in the following description radio network infrastructure equipment comprising functionality associated with the physical layer and above for the protocol stack associated with the functionality of scheduling and security of the combined CU and DU will be referred to as a first radio node whereas the radio network transmission and reception at the physical layer forming a wireless access interface for transmitting and receiving data to communications devices / UEs will be referred to as the RU or second radio node.

[0062] As shown in Figures 6a and 6b, the first radio node 602 has functionality associated both the CU 606 and the DU 604 corresponding to the functionality of the CU and DU of the gNB shown in Figures 4a and 4b. However, these functions may be adapted in accordance with a rationalisation and simplification resultingfrom removal of a formalised split between the CU and the DU. For example, transport processing may be formed by transport processes 605b and 605a, although in practice these may be the same unit. Correspondingly, the physical layer and transport layer functionality 612b may be formed and may be adapted with respect to the DU functionality shown in Figure 4, although there may be some adaptation in accordance with the merged functionality within the first radio node 602. Corresponding to the example shown in Figure 4, the SDAP 402b and PDCP 404b and the RUC 406b and MAC 408b will be largely unchanged because these communicate with corresponding components within the UE 14. Eikewise, in the radio unit or second radio node 600, the physical layer components 410b will be the same as that shown in Figure 4b although there may be some adaptation of the physical layer and transport functions 610c, 612a. Correspondingly, the interfaces between the physical and transport functions with the second radio node and the first radio node 614, 615 may be adapted in accordance with a change in the architecture shown in Figures 6a and 6b to remove the DU-CU split. However, in other examples this functionality may be the same as that shown in Figures 4a and 4b.

[0063] As will be appreciated, one of the advantages of removing a CU-DU split is to obviate requirements to provide a second or separate security level by encrypting of different layers shown in Figure 4b, which would normally be performed by the DU, which would otherwise be required as explained above for European patent application EP21155607.1. This is because according to the architecture illustrated by Figure 6, with no formalised split between the DU and a CU, components forming corresponding file functionality of a CU and DU would be hosted or implemented by the same operator and produced by the same vendor. Similarly, a more complicated arrangement for controlling mobility as disclosed in EP22165697.8, requiring a split in some functionality between the CU and the DU is as a result of the CU-DU split.

[0064] The interface 610 between the RU or second radio node 600 and the physical layer 410a of the UE 14 corresponds to and will be the same as the CPRI interface.

[0065] According to the arrangement shown in Figure 6, an interface between CU 606 and DU 604 functionality is open in the sense that this is not specified. That is to say, the interface between the CU and the DU functionality is not specified and standardised. 5G standards provide a CU-CU interface for coordination between gNB vendors. That is to say, that is a specified interface between CUs which can be used to provide cooperation between different gNB vendors. This can be seen to correspond to an inter gNB interface like Xninterface for coordination between multi-vendor deployments in 6G. However, for a 6G architecture, gNB functions may spread across different geographical areas. Therefore, both higher layer (i.e., Xninterface) and lower layer coordination may be necessary between second radio nodes / RUs. Here the term “interface” between first radio nodes, which can be an inter 6G base station interface is not limited to "Xn interface". A new term for the inter 6G base station interface can be defined. In other words, the term "Xn interface" disclosed herein can be replaced to other inter base station interface (including inter 6G base station interface).

[0066] Two split options are possibilities, which may be used according to example embodiments:

[0067] • Upper MAC in CU-DU - lower MAC in Radio Unit (RU) (Remote Radio Head (RRH) / TxRx Point (TRP))

[0068] • Upper PHY in CU-DU - lower PHY in RU (RRH / TRP)

[0069] Figure 7 provides a schematic representation of a wireless communications network configured with a radio access network part which is adapted according to the present technique to remove a split between the CU and the DU which is illustrated in Figures 1 to 5. As shown in Figure 7, first radio nodes 602.1, 602.2 are connected to respective second radio nodes 600.1, 600.2 via an interface 615, whichcorresponds to the interface 16 between the DU and the TRP which may have similar or the same functionality. As shown in Figure 7, each of the second radio nodes / RUs 600 forms a cell 12 of the radio access network which corresponds to the arrangement shown in Figure 1. As shown in Figure 7, there is an interface 764 between the first radio nodes 602.1, 602.2 which is the Xninterface 764 and corresponds to the arrangement shown in Figure 1. Therefore Figure 7 illustrates an adapted arrangement for the wireless communications network illustrated in Figure 1 to remove a split between the CU and the DU so that the first radio nodes 602.1, 602.2 form functionality performed by the CU and the DU as illustrated in Figure 6.

[0070] Embodiments of the present technique can provide a method of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network. The method comprises controlling the second radio node to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices. The method comprises either transmitting, via a wired or point to point wireless interface between the first radio node and another first radio node, control information for supporting the transmission and / or the reception of the radio signals via the wireless access interface by the one or more communications devices or receiving the control information from the other first radio node via the interface, or controlling the second radio node to transmit the control information to another second radio node via a wireless over-the-air, OTA, interface between the second radio node and the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface, which may be a point to multipoint interface. The interface between first radio nodes may be an Xninterface, which may be a wired or wireless point to point interface.

[0071] According to example embodiments of the present technique, a wireless interface is provided between respective second radio nodes / RUs 600.1, 600.2 in addition to the interface between the first radio nodes 602.1, 602.2, which is the Xninterface 764. This arrangement is illustrated in Figure 8, which provides a simplified representation of Figure 7, to support an explanation of a wireless interface between respective second radio nodes 600.1, 600.2, shown in Figure 8, comprising an outward part 700 and a return part 702. For clarity, to distinguish this interface 700, 702 from the wireless access interface formed by the second radio nodes 600.1, 600.2 for communicating with UEs 14, the wireless interface between respective second radio nodes 600.1, 600.2 will be referred to as over-the-air (OTA) communication. The second radio nodes 600.1, 600.2 are controlled by different first radio nodes 602.1, 602.2. The second radio nodes 600.1, 600.2 form respective cells 12 to support and to provide a wireless access interface for the UEs 14.1, 14.2. According to this arrangement, an assumption is that the interface Xn764 between the first radio nodes 602.1, 602.2, may be used to exchange an initial configuration and delay agnostic configuration updates between base stations / gNBs belonging to different vendors. However, for delay critical information, over the air (OTA) updates between the second radio nodes 600.1, 600.2 can be defined via the wireless interface 700, 702. This delay critical information cannot be exchanged or preferably should not be exchanged over Xninterface due to its latency.

[0072] As shown in Figures 7 and 8, a first of the second radio nodes 600.1 communicates with a second of the second radio nodes 600.2 over the air 700, 702, based on some predefined resources. The predefined resources can be identified as part of an initial configuration via Xn interface. The initial configuration via Xnmay comprise the following:

[0073] a) Xninterface elementary procedures and global procedures as defined in TS 38.423 including node discovery, Xninterface setup, neighbour cell relations and gNB configuration, resource configuration exchange, handover signaling etc.b) Authorisation of one second radio node / RU to communicate with one or more nearby second radio node / RU (s).

[0074] c) second radio node / RU ID that will be used for the OTA communication similar to RNTI (i.e., to detect and verify the second radio node / RU).

[0075] d) Initial physical resource configurations / allocations of the wireless OTA interface formed between the second radio nodes 600.1, 600.1.

[0076] Examples of information which may be exchanged via the interface over the air 600, 602 may include:

[0077] ■ Resource coordination between second radio nodes / RUs 600.1, 600.2;

[0078] ■ An interference level between second radio nodes / RUs 600.1, 600.2;

[0079] ■ A predicted user mobility from a second radio node / RU 600.1, 600.2 belong to one vendor to a second radio node / RU 600.1, 600.2 belonging to another vendor;

[0080] ■ A blind handover request;

[0081] ■ Eower Eayer Mobility.

[0082] These examples are explained in more detail below:

[0083] Resource Coordination between Second radio Nodes / RUs

[0084] Examples of resource coordination between second radio nodes / RUs 600.1, 600.2 can include Resource Status Request / Response and Update procedures, which are already defined over Xninterface as defined in TS 38.423. The following measurements can be reported between peers using a bitmap: First Bit = PRB Periodic, Second Bit = TNL Capacity Ind Periodic, Third Bit = Composite Available Capacity Periodic, Fourth Bit =Number of Active UEs Periodic, Fifth Bit =RRC connections Periodic, Sixth Bit = NR-U Channel List Periodic. These measurements can be reported with a periodicity of 500ms, 1000ms, 2000ms, 5000ms, 10000ms. The minimum duration is 500 msec and this may not be sufficient going forward where there may be a need for quicker updates. There are limitations over Xndue to latency, so that second radio nodes / RUs 600.1, 600.2 may exchange such information over the air.

[0085] The exact resource details may not be shared over the air between second radio nodes / RUs 600.1, 600.2, in principle, due to security concerns resulting from this information being discovered by a maleficent party. For this reason, indices representing resources can be exchanged over the Xninterface which is considered as secure, and this index value can be shared between second radio nodes / RUs 600.1, 600.2 over the air. The index itself cannot be used to determine resources without knowledge of the corresponding mapping between the index and the resources. According to this approach, an exchange of exact resource details over the air can be avoided.

[0086] An example illustration of such an exchange of information between second radio nodes / RUs 600.1, 600.2 is presented by a message flow diagram shown in Figure 9, which shows a proposed message sequence including an existing resource status over Xninterface and a newly proposed resource status over-the-air between second radio nodes / RUs 600.1, 600.2. As shown in Figure 9, as a first operation, initial configuration information or node capability to support OTA interface is exchange as an Xninterface setup 900 between first radio nodes 602.1 602.2. This Xninterface setup 900 can provide configuration information which establishes procedures on the wireless OTA interface 700, 702. The first of the first radio nodes 602.1 may transmit a resource status request message 902 to the second of the first radio nodes 602.2. The first of the first radio nodes 602.1 may also transmit a resource status request message 904 to the first of the second radio nodes 600.1 which it controls. The message 904 establishes a periodicity of transmission, resource status reporting and a configuration of the wireless interface of the first of the second radio nodes 600.1. The second of the first radio nodes 602.2 also transmits a resource status request message 906 to the second of the second radio nodes 600.2 which it controls, which also establishes a periodicity of transmission and resource status reporting and a configuration of the wireless interface so that this can be established between the first and the second radio nodes 600.1, 600.2. Having establishedthe resources between the second radio nodes 600.1, 600.2, the second of the first radio nodes 602.1 transmits a resource status response message 908 comprising an indication of the resources shared between the respective second radio nodes 600.1, 600.2. Thereafter, the second radio nodes may exchange resource status information between them which may also be communicated to the first radio nodes 602.1, 602.2. In general, gNBs can exchange an average of their resource usage with their peer gNBs. One of such measurements is a percentage of resources of the wireless access interface being allocated for Guaranteed Bit Rate bearers (e.g. voice) with respect to a total capacity. This could be averaged over a sampling period and then a percentage value is exchanged with a peer gNB via the Xninterface. Accordingly, this example XnResource Status exchange can provide a percentage of physical resource blocks (PRB) being allocated for GBR bearers compared to a total of PRBs etc. This information is not time sensitive and so can be exchanged over the Xninterface. If a resource needs to be reserved for a UE, then an amount of time that it should be reserved before being released can be exchanged. The Xnresource status information is not designed to carry per UE information. However, example embodiments can be arranged to provide an exchange of signalling information about individual UEs on a UE-per-UE basis between the first radio nodes 602.1 602.2 via the Xninterface along with a mapping table. This signalling information can be used during congestion and information can be exchanged between second radio nodes / RUs 600.1, 600.2 using index from the table shared earlier. This can revert to the Xninterface when congestion begins to ease. Resource status information can be indicated using physical layer signalling, which is terminated in the second radio node 600.1, 600.2, which can be provided with an additional protocol stack for communicating with other second radio nodes 600.1, 600.2 (e.g. encrypted MAC-CE) or it could be a new interface designed to communicate between second radio nodes / RUs provided it is secure and has a low latency. Interference level between Second Radio Nodes / RUs

[0087] Similar to resource coordination, interference level or RSSI measurements may be exchanged between second radio nodes / RUs 600.1, 600.2. Furthermore, in other examples a list of used / unused physical resources may be exchanged directly between second radio nodes / RUs 600.1, 600.2. However, for security concerns, it would be preferable not to exchange this information directly between second radio node 600.1, 600.2. According to example embodiments therefore, an index or mapping table can be exchanged between the first radio nodes 602.1, 602.2 which provides a mapping between actual values and a placeholder in the index / mapping table is initially exchanged over Xninterface and then only this index or mapping table entry number is exchanged later between second radio nodes 600.1, 600.2.

[0088] Exchange of Predicted Mobility Information Between Second Radio Nodes / RUs

[0089] Example embodiments can also be arranged to exchange information between second radio nodes / RUs 610.1, 610.2 which is associated with predicted measurements or mobility information such as for example a predicted handover. Techniques associated with Life-Cycle-Management (LCM) utilise machine learning or artificial intelligence (ML / AI) which is used to generate predictions based on measurements received so that for example a handover prediction can be made, or a prediction of future measurements can be derived based on existing measurements fed to a trained model for ML / AI.

[0090] According to example embodiments such information may predict parameters or mobility decisions based on an accuracy of an AI / ML model which may be activated or deactivated in accordance with whether or not a current status of prediction is accurate or not. Such information to disable or enable an AI / ML model for use in prediction such as for mobility can be exchanged via the wireless OTA interface between second radio nodes 600.1, 600.2. Similarly, interference determination for handover prediction can be enabled / disabled and reported via the over the air interface.RRC signalling is by design not time critical. An RRC layer can use RRC signalling for configuring nondelay critical configuration and information for Life Cycle Management purposes. However, time critical information using lower layer signalling or the information exchanged at the time of handover can be exchanged directly between second radio nodes / RUs 600.1, 600.2. For example, if an applicable functionality was applicable in the source second radio node 600.1, 600.2 but then becomes non-applicable in the target second radio node 600.1, 600.2 then one option is that this information is exchanged like handover signalling i.e. target second radio node 600.1, 600.2 sends RRC signalling via target CU to the UE. Alternatively, a target second radio node 600.1, 600.2 can exchange this information with a source second radio node 600.1, 600.2 and the source second radio node 600.1, 600.2 can deactivate in the UE before handover is actually triggered. Similarly, any change in AI / ML status can be exchanged directly between second radio nodes 600.1, 600.2 over the air.

[0091] Blind Handover Request

[0092] If communication between second radio nodes / RUs 600.1, 600.2 is available then an improvement can be provided for handover failure / radio link failure detection and procedures. Normally, a UE declares RLF and then performs a cell selection and then perform RRC re-establishment procedure. According to example embodiments, a second radio nodes / RUs 600.1, 600.2 can send a signal / message when a UE has lost the connection with the hope that another second radio nodes / RUs 600.1, 600.2 in the vicinity will pick up this UE.

[0093] • This blind handover request needs to be transmitted on certain beams / directions only. Later coordination happens via Xndue to overall security.

[0094] • A temp ID, pre-allocated to the UE, is broadcast by a serving second radio node / RU and received by one or more target second radio nodes / RUs. A UE, if it has lost connection move to a channel / resource to listen to this temp ID. Alternatively, UE uses RACH with new temp ID. This procedure only works for neighbours using the OTA interface having the same frequency or alternatively OTA transmission / reception switches to the same frequency (i.e. either target cell listens at source frequency or source cell transmit at target cell frequency or both switch to a common frequency for OTA for the case of inter frequency neighbours). This can be signalled using the PHY / MAC layer or a new interface signalling between second radio nodes / RUs 600.1, 600.2.

[0095] Lower Layer Mobility

[0096] In lower layer triggered mobility (LTM), some configurations are RRC configured about the target cells / TRPs known as LTM candidate configurations. However, some configurations can be dynamically allocated when a UE is moving to the target cell. These dynamic configurations can be exchanged between the serving second radio nodes / RUs 600.1, 600.2 and the target second radio nodes / RUs 600.1, 600.2 via the wireless OTA communications. For example, RACH preamble index for the UE to synchronise with target second radio nodes / RUs 600.1, 600.2 can be exchanged between the serving second radio nodes / RUs 600.1, 600.2 and the target TRP via OTA communications, and then the serving cell informs / signals to the UE. Similarly, initial UL configured grant (CG) resource configuration and or activation of the CG resource for the UE on the target second radio nodes / RUs 600.1, 600.2 can be exchanged between the serving second radio nodes / RUs 600.1, 600.2 and the target second radio nodes / RUs 600.1, 600.2 via OTA communications, and then the serving second radio nodes / RUs 600.1, 600.2 informs / signals to the UE. Hence, these dynamically allocated resources will reduce the resource consumption (i.e., Resource preallocations for a period of time) and speed up for the UE to switch to the target cell / second radio nodes / RUs 600.1, 600.2.

[0097] According to the embodiments explained above, in one example, a vendor may supply both parts of a functional split of a gNB i.e. both CU / DU as well as RRH / RU part. However, if the interface betweensecond radio node / RU 600.1, 600.2 and the rest of the gNB functions is standardised too then, a CU may also control second radio nodes / RUs 600.1, 600.2 belonging to different vendors as well.

[0098] Figure 10 provides an example flow diagram illustrating one example in which control information is transmitted either via the interface between first radio nodes or via the wireless OTA interface between 2ndradio nodes. Figure 10 is summarized as follows:

[0099] As a first step, SI, a first of the first radio nodes (CU / DU) controls a second radio node (600.1, 600.2) to transmit radio signals via a wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices. This represents a conventional operation in which a base station or gNB forms a cell of a radio network part of a wireless communications network within which radio signals can be transmitted or received via the wireless access interface. As a second step, S2, the first of the first radio nodes (CU / DU) determines whether control information determining for supporting transmission and / or reception of the radio signals by the one or more communications devices via the wireless access interface in step SI, should be transmitted from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) or received from the other first radio node via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2). Alternatively, the first radio nodes determines whether the control information should be transmitted from the second radio node (600.1, 600.2) to the other second radio node (600.1, 600.2) or received from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712) between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2). At a decision point S3, the first radio node determines whether the control information is to be transmitted via the interface between first radio node or via the wireless OTA interface between second radio nodes. If via the interface, then processing proceeds to step S4 and the control information is transmitted via the interface between the first and second first radio nodes. If however, the control information is to be transmitted via the wireless OTA interface, then the first radio node controls the second radio node to transmit or receive the control information via the wireless OTA interface.

[0100] In respect of the aspect of the technology relating to the use of indices to identify values of parameters in a table so that whilst the table is exchanged by the interface between first radio nodes, only the indices required to select parameters need be transmitted via the wireless OTA interface between the second radio nodes to improve security. Figure 11 provides a message flow diagram illustrating this aspect. As shown in Figure 11, as a first operation 1101, the first radio node 1 / CU1 602.1 generates a table of values for one or more parameters with corresponding indices for a radio control function. The parameters are used as part of the radio control function which may be operated between second radio nodes each of which forms a cell of the radio access network and therefore the control information controls parameters of the cells formed by each second radio node to perform the radio control function. The first radio node 1 / CU 1 602.1 then shares the table 1102 with the second first radio node 2 / CU 602.2 via the interface between the first nodes radio nodes 602.1, 602.2. At further operations 1103, 1104, the first and second first radio nodes 602.1, 602.2 then share the table of values with the second radio nodes 600.1, 600.2. As such, in further operations 1105, 1106, as part of the radio control function, only an index identifying a parameter need to be shared between the second radio nodes 600.1, 600.2. As such, the first radio nodes 602.1, 602.2 control the second radio nodes 600.1, 600.1 to transmit or to receive an index of the table identifying a parameter of the radio control function. Therefore, at operation 1107, only the index of the table is transmitted or received by respective second radio nodes 600.1, 600.2. Accordingly, an advantage is provided in improving both a speed at which control parameters can be communicated as part of a radio control function and a security of those parameters since only the index is shared and unless the mapping table is known, the index alone cannot be used to determine the value of the parameter being communicated.Those skilled in the art would further appreciate that such infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure.

[0101] The following numbered paragraphs provide further example aspects and features of the present technique:

[0102] Paragraph 1. A method of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprising

[0103] controlling the second radio node to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices, and either

[0104] transmitting control information for supporting the transmission and / or reception of the radio signals via the wireless access interface by the one or more communications devices via an interface from the first radio node to the other first radio node or receiving the control information from the other first radio node via the interface, or

[0105] controlling the second radio node to transmit the control information to another second radio node via a wireless over-the-air, OTA, interface between the second radio node and the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface.

[0106] Paragraph 2. A method of paragraph 1, comprising

[0107] determining, by the first radio node whether the control information for supporting transmission and / or reception of the radio signals by the one or more communications devices via the wireless access interface should be transmitted from the first radio node to the other first radio node via the interface or received from the other first radio node via the interface or transmitted from the second radio node to the other second radio node or received by the second radio node from the other second radio node via the wireless OTA interface between the second radio node and the other second radio node , and according to the determination either

[0108] transmitting the control information via the interface from the first radio node to the other first radio node or receiving the control information from the other first radio node via the interface, or controlling the second radio node to transmit the control information via the wireless OTA interface to the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface.

[0109] Paragraph 3. A method of paragraph 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node via the interface between the first radio node and the other first radio node or transmitted or received by the second radio node to or from the other second radio node via the wireless over-the-air, OTA, interface comprises

[0110] identifying whether the control information is delay intolerant or delay tolerant, and

[0111] if the control information is identified as being delay intolerant, determining that the control information should be transmitted via the wireless OTA interface between the second radio node and the other second radio node , or

[0112] if the control information is identified as being delay intolerant, determining that the control information can be transmitted via the interface between the first radio node and the other first radio node. Paragraph 4. A method of paragraph 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprisesdetermining a type of the control information and using predetermined rules to identify whether the control information is delay tolerant or delay intolerant based on type of the control information. Paragraph 5. A method of paragraph 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprises

[0113] identifying a radio control function for which the control information is being communicated and using predetermined rules to identify whether the control information is delay tolerant or delay intolerant based on the radio control function for which the control information is being communicated.

[0114] Paragraph 6. A method of paragraph 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprises

[0115] identifying that the control information is delay intolerant if the control information must be communicated within a predetermined time and otherwise identifying that the control information is delay tolerant.

[0116] Paragraph 7. A method of paragraph 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node via the interface between the first radio node and the other first radio node or transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface comprises

[0117] identifying a radio control function for which the control information is being communicated and using predetermined rules to identify whether the control information should be transmitted to or received from the other first radio node via the interface or transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface.

[0118] Paragraph 8. A method of paragraph 7, wherein the radio control function includes radio resource management.

[0119] Paragraph 9. A method of paragraph 7 or 8, wherein the control information coordinates a use of radio resources between the second radio node and the other second radio node and the predetermined rules identify that the control information coordinating the use of radio resource should be transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface. Paragraph 10. A method of paragraph 7, wherein the radio control function includes interference management.

[0120] Paragraph 11. A method of paragraph 7 or 10, wherein the control information includes information for reducing interference for coordinating a use of radio resources between the second radio node and the other second radio node to reduce interference between the one or more communications devices, which should be transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface.

[0121] Paragraph 12. A method of paragraph 7, wherein the radio control function is a life-cycle management, LCM of one or more of the communications devices.

[0122] Paragraph 13. A method of paragraph 7 or 12, wherein the control information includes information indicating whether an artificial intelligence or machine learning, AI / ML model for LCM which should be transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface.

[0123] Paragraph 14. A method of paragraph 7, wherein the radio control function includes radio link failure recovery.

[0124] Paragraph 15. A method of paragraph 7 or 14, wherein the control information includes information for a handover of a communications device following radio link failure so that the communications device, having suffered a radio link failure, can be handed over to either the second radio node or the other second radio node by transmitting the control information to the other second radio node or receiving the control information from the other second radio node via the wireless OTA interface.

[0125] Paragraph 16. A method of paragraph 15, comprising

[0126] transmitting, in response to receiving the control information, a temporary ID for the handover of the communications device.Paragraph 17. A method of paragraph 15, comprising

[0127] receiving, in response to transmitting the temporary ID a random access channel preamble which includes the temporary ID.

[0128] Paragraph 18. A method of paragraph 7, wherein the radio control function includes lower layer triggered mobility.

[0129] Paragraph 19. A method of paragraph 7 or 16, wherein the control information includes information for mobility management of a communications device triggered by a lower layer transmitted to or received from the other second radio node via the wireless OTA interface.

[0130] Paragraph 20. A method of paragraph 19, wherein the information for mobility management includes a dynamic allocation of resources on either the second radio node as a handover target or the other second radio node as the handover target.

[0131] Paragraph 21. A method of paragraph 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node via the interface between the first radio node and the other first radio node or transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface comprises

[0132] exchanging signalling information between the first radio node and the at least one other first radio node via the Xninterface identifying a resource allocation for each communications device as a mapping table identifying the resource as an index,

[0133] determining a level of congestion for transmitting to the one or more communications devices or receiving from the one or more communications devices via the wireless access interface , depending on the level of congestion, transmitting or receiving one or more indices via the wireless OTA interface to indicate the level of congestion between the second radio node and the other second radio node via the wireless OTA interface, or

[0134] transmitting or receiving an indication of resources or level of congestion via the interface between the first radio node and the other first radio node.

[0135] Paragraph 22. A method of paragraph 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node via the interface between the first radio node and the other first radio node or transmitted or received by the second radio node to or from the other second radio node via the wireless OTA interface comprises

[0136] based on whether the control information is for a higher layer function or a lower layer function, determining to transmit or to receive the control information via the interface for the higher layer function or determining to transmit or to receive the control information via the wireless OTA interface for the lower layer function.

[0137] Paragraph 23. A method of any of paragraphs 1 to 22, wherein the second radio node comprises a functional part of a base station together with the first radio node, the second radio node including at least a part of a layer 1 function, and does not include at least a part of a layer 2 and a higher layer functions, and the first radio node hosts at least a part of the layer 2 and the higher layer function and does not host at least a part of the layer 1 function.

[0138] Paragraph 24. A method of any of paragraphs 1 to 22, wherein the interface between the first radio node and the other first radio node is a point to point wired or wireless interface.

[0139] Paragraph 25. A method of paragraph 24, wherein the interface is an Xninterface.

[0140] Paragraph 26. A method of operating a first radio node to control a second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprising

[0141] transmitting control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via an interface between a first radio node and another first radio node or receiving the control information from the other first radio node via the interface, the control information comprising a plurality of values for one or more parameters for aradio control function, and an index identifying each of the plurality of values for each of the one or more parameters, and

[0142] controlling the second radio node to transmit one or more indices indicating a selected value for one or more of the parameters via the wireless over-the-air, OTA, interface to the other second radio node or controlling the second radio node to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface, the one or indices indicating the selected value of the one or more parameters for the radio control function.

[0143] Paragraph 27. A method of paragraph 26, wherein the radio control function includes radio resource management, one of the parameters representing radio resources and one of the indices selecting one or more radio resources.

[0144] Paragraph 28. A method of paragraph 26, wherein the radio control function includes interference management, one of the parameters representing an interference level for one or more radio resources and one of the indices selecting one or more interference levels of the radio resources.

[0145] Paragraph 29. A method of paragraph 26, wherein the radio control function is a life-cycle management, LCM for one or more of the communications devices, one or more of the indices indicating whether to enable or disable one or more artificial intelligence or machine learning, AI / ML models / fiinctionalities for LCM.

[0146] Paragraph 30. A method of paragraph 26, wherein the radio control function includes radio link failure recovery, the indices representing one of more the parameter values for recovering from radio link failure. Paragraph 31. A method of paragraph 26, wherein the radio control function includes lower layer triggered mobility, and one of the parameters represents radio resources and one of the indices selecting one or more of the radio resources.

[0147] Paragraph 32. A method of paragraph 26, wherein the radio control function includes a blind handover, and one of the indices selecting one or more radio resources for the blind handover.

[0148] Paragraph 33. A first radio node comprising

[0149] a first interface with another first radio node,

[0150] a second interface with a second radio node ,

[0151] a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitry

[0152] to control the second radio node which in combination with the first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network, to control the second radio node to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices, and either

[0153] to transmit control information for supporting the transmission and / or reception of the radio signals via the wireless access interface by the one or more communications devices via the first interface from the first radio node to the other first radio node or receiving the control information from the other first radio node via the interface, or

[0154] to control the second radio node to transmit the control information to another second radio node via a wireless over-the-air, OTA, interface between the second radio node and the other second radio node or controlling the second radio node to receive the control information from the other second radio node via the wireless OTA interface.

[0155] Paragraph 34. A first radio node comprising

[0156] a first interface with another first radio node,

[0157] a second interface with a second radio node ,

[0158] a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitry

[0159] to transmit control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via the first interface between afirst radio node and the other first radio node or receiving the control information from the other first radio node via the first interface, the control information comprising a plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, and

[0160] to control the second radio node via the second interface to transmit one or more indices indicating a selected value for one or more of the parameters via a wireless over-the-air, OTA, interface to the other second radio node or controlling the second radio node via the second interface to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface, the one or indices indicating the selected value of the one or more parameters for the radio control function.

[0161] Paragraph 35. A method of operating a second radio node which in combination with a first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprising

[0162] transmitting, under control of the first radio node, radio signals via the wireless access interface to one or more communications devices or receiving radio signals transmitted via the wireless access interface from the one or more communications devices,

[0163] transmitting one or more indices indicating a selected value for one or more parameters via a wireless over-the-air, OTA, interface to another second radio node or receiving one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface from the other second radio node, the one or indices indicating the selected value of the one or more parameters for a radio control function for supporting a transmission and / or a reception of radio signals via the wireless access interface to or from the one or more communications devices, wherein an index identifying each of the plurality of values for each of the one or more parameters is transmitted by the first radio node to another first radio node via an interface between the first radio node and the other first radio node or received by the first radio node from the other first radio node via the interface.

[0164] Paragraph 36. A second radio node which in combination with a first radio node provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the second radio node comprising

[0165] transceiver circuitry for transmitting, under control of the first radio node (602.1, radio signals via the wireless access interface to one or more communications devices and for receiving radio signals transmitted via the wireless access interface from the one or more communications devices, and for transmitting one or more indices indicating a selected value for one or more parameters via a wireless over-the-air, OTA, interface to another second radio node or receiving one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface from the other second radio node , the one or indices indicating the selected value of the one or more parameters for a radio control function for supporting a transmission and / or a reception of radio signals via the wireless access interface to or from the one or more communications devices, wherein an index identifying each of the plurality of values for each of the one or more parameters is transmitted by the first radio node to another first radio node via an interface between the first radio node and the other first radio node or received by the first radio node from the other first radio node via the interface.

[0166] Paragraph 37. A non-transitory computer-readable storage medium storing a computer program according to any of paragraphs 1 to 32 and 35.

[0167] Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.References

[0168] [1] 3GPP document, TS 38.470.

[0169] [2] 3GPP document TS 38.473.

[0170] [3] 3GPP document TS 38.401.

[0171] [4] 3GPP document TS 138472 - V15.2.0.

[0172] [5] 3GPP document TS38.300.

[0173] [6] 3GPP document TS 23.501.

[0174] [7] 3GPP document TS 36.300.

[0175] [8] European patent application number EP21155607.1

[0176] [9] European patent application number EP22165697.8

[0177]

[0010] TS 38.423 Xn interface specification

[0178]

[0011] TR 38.843 - TR for AIML PHY Rel-18

[0179]

[0012] O-RAN specification: https: / / specifications.o-ran.org / specifications 0-RAN Control, User and Synchronization Plane Specification 16.01

Claims

CLAIMS1. A method of operating a first radio node (602.1, 602.2) to control a second radio node (600.1, 600.2) which in combination with the first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprising controlling the second radio node (600.1, 600.2) to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices, and eithertransmitting control information for supporting the transmission and / or reception of the radio signals via the wireless access interface by the one or more communications devices via an interface (Xn, 764) from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the interface (Xn, 764), or controlling the second radio node (600.1, 600.2) to transmit the control information to another second radio node (600.1, 600.2) via a wireless over-the-air, OTA, interface (700, 712) between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) to receive the control information from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712).

2. A method of claim 1, comprisingdetermining, by the first radio node whether the control information for supporting transmission and / or reception of the radio signals by the one or more communications devices via the wireless access interface should be transmitted from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) via the interface (Xn, 764) or received from the other first radio node via the interface (Xn, 764) or transmitted from the second radio node (600.1, 600.2) to the other second radio node (600.1, 600.2) or received by the second radio node (600.1, 600.2) from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712) between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2), and according to the determination eithertransmitting the control information via the interface (Xn, 764) from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the interface (Xn, 764), orcontrolling the second radio node (600.1, 600.2) to transmit the control information via the wireless OTA interface (700, 712) to the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) to receive the control information from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712).

3. A method of claim 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node (602.1, 602.2) via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless over-the-air, OTA, interface (700, 712) comprisesidentifying whether the control information is delay intolerant or delay tolerant, andif the control information is identified as being delay intolerant, determining that the control information should be transmitted via the wireless OTA interface between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2), orif the control information is identified as being delay intolerant, determining that the control information can be transmitted via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2).

4. A method of claim 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprisesdetermining a type of the control information and using predetermined rules to identify whether the control information is delay tolerant or delay intolerant based on type of the control information.

5. A method of claim 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprisesidentifying a radio control function for which the control information is being communicated and using predetermined rules to identify whether the control information is delay tolerant or delay intolerant based on the radio control function for which the control information is being communicated.

6. A method of claim 3, wherein the identifying whether the control information is delay intolerant or delay tolerant, comprisesidentifying that the control information is delay intolerant if the control information must be communicated within a predetermined time and otherwise identifying that the control information is delay tolerant.

7. A method of claim 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node (602.1, 602.2) via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712) comprisesidentifying a radio control function for which the control information is being communicated and using predetermined rules to identify whether the control information should be transmitted to or received from the other first radio node (602.1, 602.2) via the interface (Xn, 764) or transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface.

8. A method of claim 7, wherein the radio control function includes radio resource management.

9. A method of claim 7, wherein the control information coordinates a use of radio resources between the second radio node and the other second radio node and the predetermined rules identify that the control information coordinating the use of radio resource should be transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface.

10. A method of claim 7, wherein the radio control function includes interference management.

11. A method of claim 7, wherein the control information includes information for reducing interference for coordinating a use of radio resources between the second radio node and the other second radio node to reduce interference between the one or more communications devices, which should be transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface.

12. A method of claim 7, wherein the radio control function is a life-cycle management, LCM of one or more of the communications devices.

13. A method of claim 7, wherein the control information includes information indicating whether an artificial intelligence or machine learning, AI / ML model for LCM which should be transmitted orreceived by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface.

14. A method of claim 7, wherein the radio control function includes radio link failure recovery.

15. A method of claim 7, wherein the control information includes information for a handover of a communications device following radio link failure so that the communications device, having suffered a radio link failure, can be handed over to either the second radio node or the other second radio node by transmitting the control information to the other second radio node or receiving the control information from the other second radio node via the wireless OTA interface (700, 702).

16. A method of claim 15, comprisingtransmitting, in response to receiving the control information, a temporary ID for the handover of the communications device.

17. A method of claim 15, comprisingreceiving, in response to transmitting the temporary ID a random access channel preamble which includes the temporary ID.

18. A method of claim 7, wherein the radio control function includes lower layer triggered mobility.

19. A method of claim 7, wherein the control information includes information for mobility management of a communications device triggered by a lower layer transmitted to or received from the other second radio node via the wireless OTA interface (700, 702).

20. A method of claim 19, wherein the information for mobility management includes a dynamic allocation of resources on either the second radio node as a handover target or the other second radio node as the handover target.

21. A method of claim 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node (602.1, 602.2) via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or transmitted or received by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712) comprisesexchanging signalling information between the first radio node (602.1) and the at least one other first radio node (602.2) via the Xninterface identifying a resource allocation for each communications device as a mapping table identifying the resource as an index,determining a level of congestion for transmitting to the one or more communications devices or receiving from the one or more communications devices via the wireless access interface , depending on the level of congestion, transmitting or receiving one or more indices via the wireless OTA interface to indicate the level of congestion between the second radio node and the other second radio node via the wireless OTA interface, ortransmitting or receiving an indication of resources or level of congestion via the interface between the first radio node and the other first radio node.

22. A method of claim 2, wherein the determining whether the control information should be transmitted to or received from the other first radio node (602.1, 602.2) via the interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or transmitted orreceived by the second radio node (600.1, 600.2) to or from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712) comprisesbased on whether the control information is for a higher layer function or a lower layer function, determining to transmit or to receive the control information via the interface for the higher layer function or determining to transmit or to receive the control information via the wireless OTA interface for the lower layer function.

23. A method of claim 1, wherein the second radio node comprises a functional part of a base station together with the first radio node, the second radio node including at least a part of a layer 1 function, and does not include at least a part of a layer 2 and a higher layer functions, and the first radio node hosts at least a part of the layer 2 and the higher layer function and does not host at least a part of the layer 1 function.

24. A method of claim 1, wherein the interface between the first radio node and the other first radio node is a point to point wired or wireless interface.

25. A method of claim 24, wherein the interface is an Xninterface.

26. A method of operating a first radio node (602.1, 602.2) to control a second radio node (600.1, 600.2) which in combination with the first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprising transmitting control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via an interface (Xn, 764) between a first radio node (602.1, 602.2) and another first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the interface (Xn, 764), the control information comprising a plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, and controlling the second radio node (600.1, 600.2) to transmit one or more indices indicating a selected value for one or more of the parameters via the wireless over-the-air, OTA, interface (700, 712) to the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712), the one or indices indicating the selected value of the one or more parameters for the radio control function.

27. A method of claim 26, wherein the radio control function includes radio resource management, one of the parameters representing radio resources and one of the indices selecting one or more radio resources.

28. A method of claim 26, wherein the radio control function includes interference management, one of the parameters representing an interference level for one or more radio resources and one of the indices selecting one or more interference levels of the radio resources.

29. A method of claim 26, wherein the radio control function is a life-cycle management, LCM for one or more of the communications devices, one or more of the indices indicating whether to enable or disable one or more artificial intelligence or machine learning, AI / ML models / fimctionalities for LCM.

30. A method of claim 26, wherein the radio control function includes radio link failure recovery, the indices representing one of more the parameter values for recovering from radio link failure.

31. A method of claim 26, wherein the radio control function includes lower layer triggered mobility, and one of the parameters represents radio resources and one of the indices selecting one or more of the radio resources.

32. A method of claim 26, wherein the radio control function includes a blind handover, and one of the indices selecting one or more radio resources for the blind handover.

33. A first radio node (602.1, 602.2) comprisinga first interface with another first radio node,a second interface with a second radio node (600.1, 600.2),a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitryto control the second radio node (600.1, 600.2) which in combination with the first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network,to control the second radio node (600.1, 600.2) to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices, and eitherto transmit control information for supporting the transmission and / or reception of the radio signals via the wireless access interface by the one or more communications devices via the first interface (Xn, 764) from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the interface (Xn, 764), or to control the second radio node (600.1, 600.2) to transmit the control information to another second radio node (600.1, 600.2) via a wireless over-the-air, OTA, interface (700, 712) between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) to receive the control information from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712).

34. A first radio node (602.1, 602.2) comprisinga first interface with another first radio node,a second interface with a second radio node (600.1, 600.2),a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitryto transmit control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via the first interface (Xn, 764) between a first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the first interface (Xn, 764), the control information comprising a plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, andto control the second radio node (600.1, 600.2) via the second interface to transmit one or more indices indicating a selected value for one or more of the parameters via a wireless over-the-air, OTA, interface (700, 712) to the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) via the second interface to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712), the one or indices indicating the selected value of the one or more parameters for the radio control function.

35. A method of operating a second radio node (600.1, 600.2) which in combination with a first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the method comprisingtransmitting, under control of the first radio node (602.1, radio signals via the wireless access interface to one or more communications devices or receiving radio signals transmitted via the wireless access interface from the one or more communications devices,transmitting one or more indices indicating a selected value for one or more parameters via a wireless over-the-air, OTA, interface (700, 712) to another second radio node (600.1, 600.2) or receiving one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712) from the other second radio node (600.1, 600.2), the one or indices indicating the selected value of the one or more parameters for a radio control function for supporting a transmission and / or a reception of radio signals via the wireless access interface to or from the one or more communications devices, wherein an index identifying each of the plurality of values for each of the one or more parameters is transmitted by the first radio node (602.1, 602.2) to another first radio node (602.1, 602.2) via an interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or received by the first radio node (602.1, 602.2) from the other first radio node (602.1, 602.2) via the interface.

36. A second radio node (600.1, 600.2) which in combination with a first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the second radio node comprisingtransceiver circuitry for transmitting, under control of the first radio node (602.1, radio signals via the wireless access interface to one or more communications devices and for receiving radio signals transmitted via the wireless access interface from the one or more communications devices, and for transmitting one or more indices indicating a selected value for one or more parameters via a wireless over-the-air, OTA, interface (700, 712) to another second radio node (600.1, 600.2) or receiving one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712) from the other second radio node (600.1, 600.2), the one or indices indicating the selected value of the one or more parameters for a radio control function for supporting a transmission and / or a reception of radio signals via the wireless access interface to or from the one or more communications devices, wherein an index identifying each of the plurality of values for each of the one or more parameters is transmitted by the first radio node (602.1, 602.2) to another first radio node (602.1, 602.2) via an interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or received by the first radio node (602.1, 602.2) from the other first radio node (602.1, 602.2) via the interface.

37. Circuitry for a first radio node (602.1, 602.2) comprisinga first interface with another first radio node,a second interface with a second radio node (600.1, 600.2),a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitryto control the second radio node (600.1, 600.2) which in combination with the first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network,to control the second radio node (600.1, 600.2) to transmit radio signals via the wireless access interface to one or more communications devices or to receive radio signals transmitted via the wireless access interface from the one or more communications devices, and eitherto transmit control information for supporting the transmission and / or reception of the radio signals via the wireless access interface by the one or more communications devices via the first interface(Xn, 764) from the first radio node (602.1, 602.2) to the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the interface (Xn, 764), or to control the second radio node (600.1, 600.2) to transmit the control information to another second radio node (600.1, 600.2) via a wireless over-the-air, OTA, interface (700, 712) between the second radio node (600.1, 600.2) and the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) to receive the control information from the other second radio node (600.1, 600.2) via the wireless OTA interface (700, 712).

38. Circuitry for a first radio node (602.1, 602.2) comprisinga first interface with another first radio node,a second interface with a second radio node (600.1, 600.2),a processor circuitry and a store for storing program code, which when executed by the processor circuitry configures the processor circuitryto transmit control information for supporting a transmission and / or a reception of radio signals via the wireless access interface by one or more communications devices via the first interface (Xn, 764) between a first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or receiving the control information from the other first radio node (602.1, 602.2) via the first interface (Xn, 764), the control information comprising a plurality of values for one or more parameters for a radio control function, and an index identifying each of the plurality of values for each of the one or more parameters, andto control the second radio node (600.1, 600.2) via the second interface to transmit one or more indices indicating a selected value for one or more of the parameters via a wireless over-the-air, OTA, interface (700, 712) to the other second radio node (600.1, 600.2) or controlling the second radio node (600.1, 600.2) via the second interface to receive one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712), the one or indices indicating the selected value of the one or more parameters for the radio control function.

39. Circuitry for a second radio node (600.1, 600.2) which in combination with a first radio node (602.1, 602.2) provides a wireless access interface for a cell of a radio access network part of a wireless communications network, the circuitry comprisingtransceiver circuitry for transmitting, under control of the first radio node (602.1, radio signals via the wireless access interface to one or more communications devices and for receiving radio signals transmitted via the wireless access interface from the one or more communications devices, and for transmitting one or more indices indicating a selected value for one or more parameters via a wireless over-the-air, OTA, interface (700, 712) to another second radio node (600.1, 600.2) or receiving one or more indices indicating a selected value for one or more of the parameters via the wireless OTA interface (700, 712) from the other second radio node (600.1, 600.2), the one or indices indicating the selected value of the one or more parameters for a radio control function for supporting a transmission and / or a reception of radio signals via the wireless access interface to or from the one or more communications devices, wherein an index identifying each of the plurality of values for each of the one or more parameters is transmitted by the first radio node (602.1, 602.2) to another first radio node (602.1, 602.2) via an interface (Xn, 764) between the first radio node (602.1, 602.2) and the other first radio node (602.1, 602.2) or received by the first radio node (602.1, 602.2) from the other first radio node (602.1, 602.2) via the interface.

40. A non-transitory computer-readable storage medium storing a computer program according to any of claims 1 to 32 and 35.

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