Baseband node selection for radio unit

Description

[0001] BASEBAND NODE SELECTION FOR RADIO UNIT

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to methods, a radio network node, a donor network node, computer programs, and a computer program product for connecting a radio unit to a baseband node. Further embodiments presented herein relate to a method, a server device, a computer program, and a computer program product for selecting a baseband node for a radio unit.

[0004] BACKGROUND

[0005] Many modern wireless communication systems rely on advanced beamforming techniques and power-efficient wideband transceivers implementing orthogonal frequency-division multiplexing (OFDM) based communication over multiple frequency bands that can be aggregated to provide ubiquitous high-bandwidth low-latency access.

[0006] Radio site densification (both outdoors and indoors) can be used as part of increasing the area capacity (e.g., expressed in terms of bits per second per area) in dense urban environments. In this respect, the functionality of traditional radio access network nodes, or base stations, is split between radio units and baseband units. This enables more than one distributed unit to be connected to one and the same central unit.

[0007] With an increased deployment of radio sites also follows an increase of the density of both fronthaul networks and backhaul networks. Today in dense urban environment, the communication interface between the fronthaul and the backhaul is mainly provided via fiber-optical communication, free space optical communication, or microwave links. Existing alternatives based on wireless communication for providing fronthaul transport solely rely on proprietary interfaces.

[0008] With low layer split deployments, the fronthaul connection between the radio units and the baseband units is mainly provided using wired connections. However, given an assumption of a need of ultra-dense deployment of radio units it might be both costly and sometimes infeasible to install wired connections everywhere. The degree of infrastructure work required for digging cables are sometime not even allowed (e.g., in historical areas of some cities). An alternative to use wired connections for connecting the radio units to the baseband units is thus needed. In this respect, the wireless part of the fronthaul link is traditionally based on proprietary technologies. This requires specific non-standard technologies for both the connection and operation. In turn, this implies single-vendor equipment for most of the components in the (radio) access network and thus prevents interconnecting some radio units with some baseband units.

[0009] Hence, there is still a need for an improved communication interface between distributed units and centralized units. SUMMARY

[0010] An object of embodiments herein is to address the above issues and provide a communication interface between radio units and baseband units that does not suffer from the above issues, or where the above issues at least are mitigated or reduced.

[0011] One advantages of lower layer split deployments is that radio units can be deployed after the baseband units have been deployed. A particular object is therefore to enable discovery of which baseband units are available, and suitable, for a newly deployed radio unit.

[0012] According to a first aspect there is presented a method for connecting a radio unit to a baseband node. The method is performed by a radio network node. The radio network node comprises an MT interface and hosts the radio unit. The method comprises establishing a wireless connection between the MT interface and a UPF of a donor network node. The method comprises connecting to the baseband node paired with the radio unit upon providing information about capabilities of the radio unit and parameters of the wireless connection to a server device, and upon obtaining information from the server device about the baseband node. The method comprises transporting fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and the UPF of the donor network node.

[0013] According to a second aspect there is presented a radio network node for connecting a radio unit to a baseband node. The radio network node comprises an MT interface and hosts the radio unit. The radio network node comprises processing circuitry. The processing circuitry is configured to cause the radio network node to establish a wireless connection between the MT interface and a UPF of a donor network node. The processing circuitry is configured to cause the radio network node to connect to the baseband node paired with the radio unit upon providing information about capabilities of the radio unit and parameters of the wireless connection to a server device, and upon obtaining information from the server device about the baseband node. The processing circuitry is configured to cause the radio network node to transport fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and the UPF of the donor network node.

[0014] According to a third aspect there is presented a computer program for connecting a radio unit to a baseband node. The computer program comprises computer program code which, when run on processing circuitry of a radio network node, that comprises an MT interface and hosts the radio unit, causes the radio network node to perform actions. One action comprises the radio network node to establish a wireless connection between the MT interface and a UPF of a donor network node. One action comprises the radio network node to connect to the baseband node paired with the radio unit upon providing information about capabilities of the radio unit and parameters of the wireless connection to a server device, and upon obtaining information from the server device about the baseband node. One action comprises the radio network node to transport fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and the UPF of the donor network node.

[0015] According to a fourth aspect there is presented a method for selecting a baseband node for a radio unit. The method is performed by a server device. The method comprises receiving information from a radio network node hosting the radio unit about capabilities of the radio unit and parameters of a wireless connection established between an MT interface of the radio network node and a donor network node. The wireless connection is to be used for transporting fronthaul traffic between the radio unit and the baseband node. The method comprises selecting the baseband node from a set of baseband nodes based on the capabilities of the radio unit and the parameters of a wireless connection. The method comprises sending information to the radio network node about the selected baseband node.

[0016] According to a fifth aspect there is presented a server device for selecting a baseband node for a radio unit. The server device comprises processing circuitry. The processing circuitry is configured to cause the server device to receive information from a radio network node hosting the radio unit about capabilities of the radio unit and parameters of a wireless connection established between an MT interface of the radio network node and a donor network node. The wireless connection is to be used for transporting fronthaul traffic between the radio unit and the baseband node. The processing circuitry is configured to cause the server device to select the baseband node from a set of baseband nodes based on the capabilities of the radio unit and the parameters of a wireless connection. The processing circuitry is configured to cause the server device to send information to the radio network node about the selected baseband node.

[0017] According to a sixth aspect there is presented a computer program for selecting a baseband node for a radio unit. The computer program comprises computer program code which, when run on processing circuitry of a server device, causes the server device to perform actions. One action comprises the server device to receive information from a radio network node hosting the radio unit about capabilities of the radio unit and parameters of a wireless connection established between an MT interface of the radio network node and a donor network node. The wireless connection is to be used for transporting fronthaul traffic between the radio unit and the baseband node. One action comprises the server device to select the baseband node from a set of baseband nodes based on the capabilities of the radio unit and the parameters of a wireless connection. One action comprises the server device to send information to the radio network node about the selected baseband node.

[0018] According to a seventh aspect there is presented a method for connecting a radio unit to a baseband node. The method is performed by a donor network node. The method comprises establishing a wireless connection between the donor network node and an MT interface of a radio network node that hosts the radio unit. The method comprises transporting fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and a UPF of the donor network node, thereby connecting the radio unit to the baseband node. According to an eighth aspect there is presented a donor network node for connecting a radio unit to a baseband node. The donor network node comprises processing circuitry. The processing circuitry is configured to cause the donor network node to establish a wireless connection between the donor network node and an MT interface of a radio network node that hosts the radio unit. The processing circuitry is configured to cause the donor network node to transport fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and a UPF of the donor network node, thereby connecting the radio unit to the baseband node.

[0019] According to a ninth aspect there is presented a computer program for connecting a radio unit to a baseband node, the computer program comprising computer program code which, when run on processing circuitry of a donor network node, causes the donor network node to perform actions. One action comprises the donor network node to establish a wireless connection between the donor network node and an MT interface of a radio network node that hosts the radio unit. One action comprises the donor network node to transport fronthaul traffic between the radio unit and the baseband node over the wireless connection, and in a PDU session between the MT interface and a UPF of the donor network node, thereby connecting the radio unit to the baseband node.

[0020] According to a tenth aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect, the sixth aspect, and the ninth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium can be a non-transitory computer readable storage medium.

[0021] Advantageously, these aspects enable a standard radio protocol to be used for establishing connectivity for the fronthaul traffic from the radio unit to the baseband node where part of the fronthaul link is transported over a wireless link.

[0022] Advantageously, these aspects enable a suitable baseband node to be selected, and operatively connected to, the radio unit.

[0023] Advantageously, these aspects for wireless fronthaul can be combined with wireless self-backhauling.

[0024] Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0025] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0027] Fig. 1 is a schematic block diagram for a 5G system architecture according to embodiments;

[0028] Figs. 2, 3, and 4 are flowcharts of methods according to embodiments;

[0029] Fig. 5 is a schematic illustration of PDU sessions according to embodiments;

[0030] Fig. 6 is a schematic illustration of selection of a baseband node for a radio unit according to embodiments;

[0031] Fig. 7 is a schematic illustration of a protocol stack according to embodiments;

[0032] Fig. 8 is a schematic illustration of communication between a donor network node, radio network nodes, and UEs according to embodiments;

[0033] Figs. 9 and 10 are signaling diagrams of methods according to embodiments;

[0034] Fig. 11 is a schematic diagram showing structural units of a radio network node according to an embodiment;

[0035] Fig. 12 is a schematic diagram showing structural units of a server device according to an embodiment;

[0036] Fig. 13 is a schematic diagram showing structural units of a donor network node according to an embodiment; and

[0037] Fig. 14 shows one example of a computer program product comprising computer readable means according to an embodiment.

[0038] DETAILED DESCRIPTION

[0039] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0040] Some (radio) access network architectures define network nodes (or gNBs) comprising multiple component parts or nodes, such as one or more radio units that can be connected to one or more baseband units. This is what above is referred to as low layer split deployments. Accordingly, the protocol layer stack of the network node can be divided between the baseband units and the radio units, with one or more lower layers of the stack implemented in the radio units, and one or more higher layers of the stack implemented in the baseband units. The radio units are connected to the baseband units via a fronthaul lower-layer split (LLS) network. A communication link for communication of user data messages or packets between the RU and the baseband unit, CU, or DU is referred to as a fronthaul network or interface. Messages or packets may be transmitted from the network node 200 in the downlink (i.e., from the CU to the RU) or received by the network node 200 in the uplink (i.e., from the RU to the CU).

[0041] An alternative to lower the cost of deployment and increase spectrum utilization is for operators to use self- backhauling radio access technologies, such as Integrated Access and Backhaul (IAB) where the main principle is the use of wireless links for the backhaul communication to enable flexible and very dense deployment of cells without the need for densifying the wired transport network. Accordingly, a so-called donor network node, which is a radio access node with a wired connection to the core network, is providing a wireless backhaul connection to one or more other radio access nodes, which in turn might provide wireless backhaul connections to one or more further radio access nodes, etc. The donor network node and the other radio access nodes are also configured to provide network access to ordinary pieces of user equipment (UEs).

[0042] At least some of the herein disclosed embodiments are based on combining principles of lower layer split deployments with the principles of IAB.

[0043] According to at least some of the herein disclosed embodiments there is disclosed techniques for a lower-layer split implementation of a radio network node where some part of the link between a baseband node and a radio unit is transmitted over a standardized wireless air interface. The baseband node could be a traditional baseband unit (e.g., responsible for parts of the physical layer processing, including baseband signal processing, for performing scheduling and layers 2 and 3 processing functions) with dedicated hardware or a cloud-based virtualized baseband unit whose functionality is distributively implemented by one or several servers in a computational cloud. A macro radio network node, hereinafter referred to as a donor network node, can be used to transport fronthaul traffic from the baseband node to its associated radio unit. This fronthaul traffic can be transported over a radio bearer toward a micro or pico radio network node, hereinafter referred to as a child network node, which hosts a UE / MT functionality that terminates the NR Uu radio protocol between the donor network node and the UE / MT and then forwards the fronthaul traffic to a radio unit also hosted in the child network node.

[0044] According to at least some of the herein disclosed embodiments there is disclosed techniques for selecting which radio unit to be paired with which baseband node and over which type of fronthaul interface the selected radio unit and baseband node are to communicate with each other. According to at least some of the herein disclosed embodiments there is disclosed techniques for load balancing being performed for the donor network node to at the same time serve both its own user equipment (UE) and act as a donor network node for one or more child network nodes.

[0045] In Fig. 1 is shown different blocks in a fifth-generation (5G) system architecture. A core network (CN) 170 is connected to a (radio) access network ((R)AN), as represented by a donor network node (DNN) 120. The N3 interface is using the General Packet Radio Service (GPRS) Tunnelling Protocol (GTP) protocol towards the (R)AN. According to at least some of the herein disclosed embodiments, a donor network node 120 in the (R)AN is used for transporting fronthaul traffic from a baseband node (BBN) 130 to a radio unit (RU) 112 in a child network node (as represented by a radio network node (RNN) 110). The UPF 180a and the baseband node 130 are operatively connected to a server device (SD) 190.

[0046] In Fig. 1, the baseband node 130 is configured to transmit fronthaul traffic towards a user plane function (UPF) 180a of the donor network node 120. The UPF itself could be implemented in a separate node or be provided as a component in the donor network node 120. The radio network node 110 is configured to transparently forward the fronthaul traffic to / from the radio unit 112. In this respect, the radio network node 110 can be implemented as a static UE, so there is no need for the radio network node 110 to implement any features enabling mobility.

[0047] Hence, in this architecture, a mobile termination (MT) interface 114 in the radio network node 110 connects to the donor network node 120 like an ordinary UE. According to at least some of the herein disclosed embodiments, the donor network node 120 is further configured to act as donor for a wireless self-backhauling RNN 150. Here, the data carried between the self-backhauling RNN 150 and the donor network node 120 is backhaul traffic. This backhaul traffic could be transported over the NR Uu interface between the self-backhauling RNN 150 and the donor network node 120. The donor node 120 is further configured to serve UEs, as represented by UE 160. A data network DN 140 represents the connection to the internet. From the DN's point of view, UPF 180b can be seen as an Internet Protocol (IP) router, since the N6 interface is simply an IP link.

[0048] Reference is next made to Fig. 2 illustrating a method for connecting a radio unit 112 to a baseband node 130 as performed by the radio network node 110 according to an embodiment. The radio network node 110 comprises an MT interface 114 and hosts the radio unit 112. With respect to the architecture in Fig. 1, in some embodiments, the radio network node 110 is a child network node with respect to the donor network node 120.

[0049] S102: The radio network node 110 establishes a wireless connection between the MT interface 114 and a UPF of a donor network node 120.

[0050] In some examples the wireless connection is established over a New Radio (NR) air interface or a Long Term Evolution (LTE) air interface between the MT interface 114 and the donor network node 120.

[0051] S104: The radio network node 110 connects to the baseband node 130 paired with the radio unit 112 upon having provided information about capabilities of the radio unit 112 and parameters of the wireless connection to a server device 190, and upon having obtained information from the server device 190 about the baseband node 130.

[0052] The radio network node 110 might find the server device 190 using suitable mechanism, such as a configured IP address, or resolve a configured domain name in a domain name system (DNS), or using service based architectures discovery service for finding the server device 190. The information might in step S104 be sent by a baseband discovery client (referred to as DC 620 in Fig. 6) in the radio network node 110. Further, the information might be sent from the MT interface 114 to donor network node 120 that will route the message containing the information route to the UPF of the donor network node 120 and then further to the server device 190.

[0053] S112: The radio network node 110 transports fronthaul traffic between the radio unit 112 and the baseband node 130 over the wireless connection, and in a protocol data unit (PDU) session between the MT interface 114 and the UPF of the donor network node 120.

[0054] When the baseband node has been selected, the attachment process of the radio unit 112 can start either from the baseband node 130 or from the radio unit 112, assuming that the server device 190 sends an acknowledgment of the selected baseband node 130 and the fronthaul identification, e.g. IP address, to be used by the radio unit 112 when transmitting fronthaul packets upstream (i.e., in the direction towards the baseband node 130).

[0055] Embodiments relating to further details of connecting a radio unit 112 to a baseband node 130 as performed by the radio network node 110 will now be disclosed with continued reference to Fig. 2.

[0056] Further aspects of establishing the wireless connection between the MT interface 114 and the UPF in step S102 will be disclosed next.

[0057] In some aspects, the radio network node 110 connects to the donor network node 120 in the same way as a traditional UE, thus going through the steps of random access messages for enabling the radio network node 110 to perform a radio resource control (RRC) connection procedure. The final step in the RRC connection procedure is for the radio network node 110 to transmit a RRCSetupComplete message. Hence, in some embodiments, the radio network node 110 is configured to perform (optional) step S102-2 as part of establishing the wireless connection in step S102.

[0058] S102-2: The radio network node 110 sends an RRCSetupComplete message to the donor network node 120. The RRCSetupComplete message comprises information that the MT interface 114 is used for transporting fronthaul traffic to and from the radio unit 112. In some aspects, the RRCSetupComplete message is piggy-backed with initial non-access stratum (NAS) message for the registration request to the core network. That is, in some embodiments, the information is comprised in a NAS message carried by the RRCSetupComplete message.

[0059] In general terms, the initial registration procedure toward the core network also comprises authentication, authorization and access stratum (AS) security procedures.

[0060] When the registration is complete, the radio network node 110 sends a registration complete message followed up with a PDU session establishment request. The PDU type in the request could be an IPv6 session.

[0061] In some aspects, the radio network node 110 will then request at least one IP address for allocating an identification to the radio unit 112. Therefore, in some embodiments, the radio network node 110 is configured to perform (optional) steps S102-4, S102-6, S102-8 as part of establishing the wireless connection in step S102.

[0062] S102-4: The radio network node 110 requests IP addresses from the UPF.

[0063] In some examples, the request is for IPv6 prefix delegation from the UPF.

[0064] S102-6: The radio network node 110 receives set of IP addresses from the UPF.

[0065] In case the request was for IPv6 prefix delegation, the radio network node 110 will receive up to 64 IP addresses.

[0066] S102-8: The radio network node 110 assigns at least one of the IP addresses to the radio unit 112.

[0067] Further aspects of the selection of the baseband node 130 to pair with the radio unit 112 will be disclosed next.

[0068] The capabilities of the radio unit 112 can be read using the management plane (M-Plane) Yet Another Next Generation (YANG), or Netconf, functionality used in the Open Radio Access Network (O-RAN) Control, User, and Synchronization (CUS) plane specification. Alternatively, a proprietary handshake protocol as implemented between the radio unit 112 and the baseband node 130 could be used for this purpose. In some embodiments, the capabilities of the radio unit 112 comprise information of supported fronthaul interfaces, supported communication capabilities, and supported communication protocols of the radio unit 112. In this respect, in some non-limiting examples, the fronthaul interfaces are one or more of: the Common Public Radio Interface (CPRI), the enhanced CPRI (eCPRI), an interface compliant with the IEEE 1914 standard, the Next Generation Fronthaul Interface (NGFI), and a proprietary interface. In some non-limiting examples, the supported communication capabilities pertain to any of: supported radio access technologies (RATs) such as the New Radio (NR) air interface or the Long Term Evolution (LTE) interface or the IEEE 802.11 suite of standards or Bluetooth, supported bandwidth ranges, supported power ranges, supported O-RAN versions, etc.

[0069] In some embodiments, the information provided to the server device 190 further comprises identity information of the radio unit 112. The identity information might be provided in terms of (unique) hardware identifier of the radio unit 112, public cryptography key of the radio unit 112, serial number of the radio unit 112, etc. This information can then be used by the server device 190 when selecting the baseband node 130 to pair with the radio unit 112.

[0070] In some aspects, the server device 190 sends an IP address to be used by the radio unit 112 when transmitting fronthaul packets upstream. Hence, in some embodiments, the information from the server device 190 about the baseband node 130 comprises an IP address of the baseband node 130, and the fronthaul traffic is addressed to the IP address of the baseband node 130.

[0071] In some aspects not only the baseband node 130 to pair with the radio unit 112 is selected, but also the type of fronthaul to be used for transporting the fronthaul traffic between the radio unit 112 and the baseband node 130. Therefore, in some embodiments, the radio network node 110 is configured to perform (optional) step S106.

[0072] S106: The radio network node 110 receives information from the server device 190 about a type of fronthaul interface to be used for transporting the fronthaul traffic between the radio unit 112 and the baseband node 130.

[0073] A selection of fronthaul interface can be made in case each of the radio unit 112 and the baseband node 130 supports communication over more than one fronthaul interface.

[0074] Further, the server device 190 might also relay configuration information of the selected fronthaul interface so that the radio unit 112 can be configured accordingly. Hence, in some embodiments, the radio network node 110 is configured to perform (optional) step S108.

[0075] S108: The radio network node 110 receives configuration data of the radio unit 112 from the baseband node 130. The configuration data is to be used by the radio unit 112 when transporting fronthaul traffic between the radio unit 112 and the baseband node 130.

[0076] The type of configuration data could be what RAT (e.g., NR, LTE) to use, antenna calibration, information about equivalent isotropic radiated power (EIRP) restrictions, which cell sectors to be activated, etc.

[0077] The radio unit 112 is then configured accordingly. That is, in some embodiments, the radio network node 110 is configured to perform (optional) step S110.

[0078] S110: The radio network node 110 configures the radio unit 112 with the configuration data.

[0079] Reference is now made to Fig. 3 illustrating a method for selecting a baseband node 130 for a radio unit 112 as performed by the server device 190 according to an embodiment. In some aspects, the server device 190 is a baseband discovery server.

[0080] As disclosed above, the radio network node 110 in step S104 provides information about capabilities of the radio unit 112 and parameters of the wireless connection to the server device 190. It is assumed that this information is received by the server device 190, as in step S202. S202: The server device 190 receives information from a radio network node 110 hosting the radio unit 112 about capabilities of the radio unit 112 and parameters of a wireless connection established between an MT interface 114 of the radio network node 110 and a donor network node 120. The wireless connection is to be used for transporting fronthaul traffic between the radio unit 112 and the baseband node 130.

[0081] S204: The server device 190 selects the baseband node 130 from a set of baseband nodes 130 based on the capabilities of the radio unit 112 and the parameters of a wireless connection.

[0082] S206: The server device 190 sends information to the radio network node 110 about the selected baseband node 130.

[0083] Embodiments relating to further details of selecting a baseband node 130 for a radio unit 112 as performed by the server device 190 will now be disclosed with continued reference to Fig. 3.

[0084] Further aspects of the selection of the baseband node 130 to pair with the radio unit 112 will be disclosed next.

[0085] As disclosed above, in some embodiments, the capabilities of the radio unit 112 comprise information of supported fronthaul interfaces, supported communication capabilities, and supported communication protocols of the radio unit 112.

[0086] Then, the selection in S204 can also take this information into account when selecting the baseband node 130. In particular, in some embodiments, the server device 190 has access to information of capacities and capabilities of the set of baseband nodes 130, and the baseband node 130 further is selected based on the capacities and capabilities of the set of baseband nodes 130. In general terms, a baseband node 130 is selected that has at least one matching supported fronthaul interface, at least one matching supported communication capability, and at least one matching supported communication protocol. Examples of fronthaul interfaces, communication capabilities, and communication protocols have been provided above and apply here as well.

[0087] As disclosed above, in some aspects, the information received from the radio network node 110 further comprises identity information of the radio unit 112. The server device 190 can then access a database where characteristics of the radio unit 112 are stored. The server device 190 can then select a baseband node 130 that matches these characteristics. Additionally or alternatively, the identity information of the radio unit 112 can be provided to the baseband node 130 for verification by the baseband node 130 that the radio unit 112 is allowed to connect to the baseband node 130 (i.e., for the baseband node 130 to verify that is services are to be made available to the radio unit 112).

[0088] As further disclosed above, also the type of fronthaul to be used for transporting the fronthaul traffic between the radio unit 112 and the baseband node 130 is selected. In particular, in some embodiments, the radio network node 110 is configured to perform (optional) steps S208 and S210. S208: The server device 190 selects a type of fronthaul interface to be used for transporting the fronthaul traffic between the radio unit 112 and the baseband node 130 based on the information of supported fronthaul interfaces of the radio unit 112 and based on capacities and capabilities of the selected baseband node 130.

[0089] S210: The server device 190 sends information to the radio network node 110 about the selected type of fronthaul interface.

[0090] As further disclosed above, the server device 190 might also relay configuration information of the selected fronthaul interface so that the radio unit 112 can be configured accordingly.

[0091] As further disclosed above, in some aspects, the server device 190 sends an IP address to be used by the radio unit 112 when transmitting fronthaul packets upstream. This information is then provided to the baseband unit 130. That is, in some embodiments, the radio network node 110 is configured to perform (optional) step S212.

[0092] S212: The server device 190 sends the IP address of the radio unit 112 to the selected baseband node 130.

[0093] Reference is now made to Fig. 4 illustrating a method for connecting a radio unit 112 to a baseband node 130 as performed by the donor network node 120 according to an embodiment.

[0094] As disclosed above, the radio network node 110 establishes a wireless connection between the MT interface 114 and a UPF of a donor network node 120. Hence, the donor network node 120 is configured to perform step S302.

[0095] S302: The donor network node 120 establishes a wireless connection between the donor network node 120 and an MT interface 114 of a radio network node 110 that hosts the radio unit 112.

[0096] As further disclosed above, in some examples the wireless connection is established over a New Radio (NR) air interface or a Long Term Evolution (LTE) air interface between the MT interface 114 and the donor network node 120.

[0097] As further disclosed above, fronthaul traffic between the radio unit 112 and the selected baseband node 130 is then transported over the wireless connection. Hence, the donor network node 120 is configured to perform step S306.

[0098] S306: The donor network node 120 transports fronthaul traffic between the radio unit 112 and the baseband node 130 over the wireless connection, and in a PDU session between the MT interface 114 and a UPF of the donor network node 120, thereby connecting the radio unit 112 to the baseband node 130.

[0099] Embodiments relating to further details of connecting a radio unit 112 to a baseband node 130 as performed by the donor network node 120 will now be disclosed with continued reference to Fig. 4. Further aspects of establishing the wireless connection between the MT interface 114 and the UPF in step S302 will be disclosed next.

[0100] As disclosed above, in some aspects, the radio network node 110 connects to the donor network node 120 in the same way as a traditional UE and transmit a RRCSetupComplete message. Hence, in some embodiments, the donor network node 120 is configured to perform (optional) step S302-2 as part of establishing the wireless connection in step S302.

[0101] S302-2: The donor network node 120 receives an RRCSetupComplete message from the radio network node 110. The RRCSetupComplete message comprises information that the MT interface 114 is used for transporting fronthaul traffic to and from the radio unit 112.

[0102] As disclosed above, in some aspects, the RRCSetupComplete message is piggy-backed with initial non-access stratum (NAS) message for the registration request to the core network. That is, in some embodiments, the information is comprised in a NAS message carried by the RRCSetupComplete message.

[0103] That is, in some aspects, the NAS message carried in the RRCSetupComplete provides information that the MT interface 114 that is connecting is used for fronthaul traffic to / from the radio unit 112. This information can be used by the donor network node 120 to select the proper access and mobility management function (AMF). Hence, in some embodiments, the donor network node 120 is configured to perform (optional) step S304.

[0104] S304: The donor network node 120 selects an AMF for the radio network node 110 based on the information that the MT interface 114 is used for transporting fronthaul traffic to and from the radio unit 112.

[0105] Here, an AMF can be selected that supports a radio unit 112 having an MT interface 114 used for transporting fronthaul traffic to and from the radio unit 112.

[0106] As disclosed above, the donor network node 120 could also support backhaul functionality. In particular, let radio network node 110 be referred to as a first radio network node 110. The donor network node 120 can then provide backhaul support for a second radio network node 150. In particular, in some embodiments, the donor network node 120 is configured to perform (optional) steps S308 and S310.

[0107] S308: The donor network node 120 establishes a wireless backhaul connection between the donor network node 120 and a second radio network node 150.

[0108] S310: The donor network node 120 transports backhaul traffic of the second radio network node 150 between the second radio network node 150 and a core network node and on the wireless backhaul connection.

[0109] In some aspects, the donor network node 120 implements a routing mechanism according to which fronthaul traffic, self-backhauling and UE user access can be allocated to different radio bearers. In particular, in some embodiments, the fronthaul traffic is transported on a first radio bearer, the backhaul traffic is transported on a second radio bearer, and the donor network node 120 serves at least one UE on a third radio bearer.

[0110] Further aspects of the UPF as belonging to the donor network node 120 will be disclosed next. In some embodiments, the UPF is hosted by the donor network node 120. In some aspects, the donor network node 120 further hosts one or more further UPFs. therefore, in some embodiments, the UPF is a first UPF, the donor network node 120 further hosts a second UPF, and the fronthaul traffic is transported between the second radio network node 150 and the second UPF.

[0111] Reference is next made to Fig. 5 in which the relevant PDU sessions are illustrated. A first PDU session is established between the MT interface in the radio network node and a UPF (denoted "UPF A”) of the donor network node for transporting fronthaul traffic between the radio unit in the radio network node and a baseband node. Further, a second PDU session is established between a UE served by the radio network node and a UPF (denoted "UPF B”) for transporting application data between the UE and a data network.

[0112] As illustrated in Fig. 6, the UPF denoted "UPF A” will route messages to the server device 190. The server device 190 will, via a switch router (SWR) 610, select a suitable baseband node to pair with the radio unit 112 in the radio network node 110 in accordance with the herein disclosed embodiments.

[0113] Fig. 7 schematically illustrates the system architecture for an implementation where the IP address of the radio unit is determined from the source address in the message so the selected baseband node 130 will get this address from the server device 190. The architecture is illustrated together with an Ethernet frame 710 as provided at the eCPRI interface of the baseband node 130. Furthermore, Fig. 7 also shows that the UPF 180a of the donor network node is attached close to the fronthaul of the baseband node 130. It is also illustrated how the IP address of the radio unit given by the server device 190 is used as destination address in an assembled fronthaul packet. The UPF will route the IP packet in a GPT tunnel toward the donor network node.

[0114] In Fig. 8 is illustrated a scenario where the donor network node 120 serves as donor network node for a fronthaul wireless link and also for a wireless self-backhauling link. The donor network node 120 also takes the role as a normal base station for one of the UEs 160. The UPF denoted "UPF A” is used for the fronthaul traffic where the input is the IP header from the baseband node and where the payload is the fronthaul traffic. The UPF denoted "UPF B” is used for the backhaul link.

[0115] Signaling diagrams for establishment of a fronthaul connection and configuration of a radio unit and a baseband node will be described next with references to Figs. 9 and 10.

[0116] In Fig. 9 is provided a signaling diagram for a procedure for setting up a fronthaul connection to between a radio unit 112 in a radio network node 110 and a baseband node 130.

[0117] S401. The radio network node 110 is powered up. 5402. The MT interface 114 in the radio network node 110 starts a cell search procedure to find a cell to camp on. The MT interface 114 connects the radio network node 110 to the donor network node as a normal UE, thus going through the steps of random access messages for enabling the radio network node 110 to perform a RRC connection procedure.

[0118] 5403. The radio network node 110 is registered and authorized / authenticated towards the core network.

[0119] 5404. The MT interface 114 starts a PDU session.

[0120] 5405. The MT interface 114 requests IPv6 prefix delegation.

[0121] 5406. The MT interface 114 provides (at least) one IP address to the radio unit 112.

[0122] 5407. The provision of the (at least one) IP address to the radio unit 112 triggers a baseband discovery client to be started in the radio network node 110.

[0123] 5408. The baseband discovery client performs the steps in Fig. 10 for pairing the radio unit 112 with a baseband node 130.

[0124] 5409. The server device 190 uses information provided from the radio network node 110 to select a baseband node 130 and fronthaul interface that is feasible for the paired radio unit 112 and baseband node 130.

[0125] 5410. The baseband node 130 starts to send data that will configure and initialize the radio unit 112.

[0126] 5411 . When the radio unit 112 is configured and initialized, fronthaul traffic is transported between the baseband node 130 and the radio unit 112.

[0127] Reference is next made to Fig. 10 illustrating a procedure for baseband node pairing as performed by the baseband discovery client.

[0128] 5501. The baseband discovery client reads out the capabilities of the radio unit 112.

[0129] 5502. The baseband discovery client sends a pairing request to the server device 190. The request comprises the capabilities and identity information of the radio unit 112 and is sent via the MT interface 114.

[0130] 5503. The baseband discovery client starts a timer to monitor any response from the server device 190.

[0131] 5504. If an acknowledgement is received from the server device 190, the baseband discovery client concludes the pairing to be successful and the procedure is ended. If not, step S505 is entered.

[0132] S505. If the response timer expires without any acknowledgement being received, step S506 is entered. If the response timer has not expired, step S504 is entered again. S506. The counter of pairing attempts is incremented and step S507 is entered.

[0133] 5507. If the maximum number of attempts is reached, step S508 is entered. Else, proceed step S502 is entered again.

[0134] 5508. The baseband discovery client informs the core network about the failed pairing. A mechanism to achieve this is to use a NAS message that is sent from the MT interface to the AMF to inform the RAN management system of the failed pairing.

[0135] Fig. 11 schematically illustrates, in terms of a number of structural units, the components of a radio network node 1110 according to an embodiment. Processing circuitry 1110 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1410a (as in Fig. 14), e.g. in the form of a storage medium 1130. The processing circuitry 1110 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0136] Particularly, the processing circuitry 1110 is configured to cause the radio network node 1110 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 1130 may store the set of operations, and the processing circuitry 1110 may be configured to retrieve the set of operations from the storage medium 1130 to cause the radio network node 1110 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 1110 is thereby arranged to execute methods as herein disclosed.

[0137] The storage medium 1130 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0138] The radio network node 1110 may further comprise a communications (comm.) interface 1120 for communications with other entities, functions, nodes, and devices, as in Fig. 1 . As such the communications interface 1120 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0139] The processing circuitry 1110 controls the general operation of the radio network node 1110 e.g. by sending data and control signals to the communications interface 1120 and the storage medium 1130, by receiving data and reports from the communications interface 1120, and by retrieving data and instructions from the storage medium 1130. Other components, as well as the related functionality, of the radio network node 1110 are omitted in order not to obscure the concepts presented herein.

[0140] Fig. 12 schematically illustrates, in terms of a number of structural units, the components of a server device 1200 according to an embodiment. Processing circuitry 1210 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1410b (as in Fig. 14), e.g. in the form of a storage medium 1230. The processing circuitry 1210 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0141] Particularly, the processing circuitry 1210 is configured to cause the server device 1200 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 1230 may store the set of operations, and the processing circuitry 1210 may be configured to retrieve the set of operations from the storage medium 1230 to cause the server device 1200 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 1210 is thereby arranged to execute methods as herein disclosed.

[0142] The storage medium 1230 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0143] The server device 1200 may further comprise a communications interface 1220 for communications with other entities, functions, nodes, and devices, as in Fig. 1. As such the communications interface 1220 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0144] The processing circuitry 1210 controls the general operation of the server device 1200 e.g. by sending data and control signals to the communications interface 1220 and the storage medium 1230, by receiving data and reports from the communications interface 1220, and by retrieving data and instructions from the storage medium 1230. Other components, as well as the related functionality, of the server device 1200 are omitted in order not to obscure the concepts presented herein.

[0145] Fig. 13 schematically illustrates, in terms of a number of structural units, the components of a donor network node 1300 according to an embodiment. Processing circuitry 1310 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 1410c (as in Fig. 14), e.g. in the form of a storage medium 1330. The processing circuitry 1310 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0146] Particularly, the processing circuitry 1310 is configured to cause the donor network node 1300 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 1330 may store the set of operations, and the processing circuitry 1310 may be configured to retrieve the set of operations from the storage medium 1330 to cause the donor network node 1300 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 1310 is thereby arranged to execute methods as herein disclosed. The storage medium 1330 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0147] The donor network node 1300 may further comprise a communications interface 1320 for communications with other entities, functions, nodes, and devices, as in Fig. 1 . As such the communications interface 1320 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0148] The processing circuitry 1310 controls the general operation of the donor network node 1300 e.g. by sending data and control signals to the communications interface 1320 and the storage medium 1330, by receiving data and reports from the communications interface 1320, and by retrieving data and instructions from the storage medium 1330. Other components, as well as the related functionality, of the donor network node 1300 are omitted in order not to obscure the concepts presented herein.

[0149] Fig. 14 shows one example of a computer program product 1410a, 1410b, 1410c comprising computer readable means 1430. On this computer readable means 1430, a computer program 1420a can be stored, which computer program 1420a can cause the processing circuitry 1110 and thereto operatively coupled entities and devices, such as the communications interface 1120 and the storage medium 1130, to execute methods according to embodiments described herein. The computer program 1420a and / or computer program product 1410a may thus provide means for performing any steps of the radio network node 1100 as herein disclosed. On this computer readable means 1430, a computer program 1420b can be stored, which computer program 1420b can cause the processing circuitry 1210 and thereto operatively coupled entities and devices, such as the communications interface 1220 and the storage medium 1230, to execute methods according to embodiments described herein. The computer program 1420b and / or computer program product 1410b may thus provide means for performing any steps of the server device 1200 as herein disclosed. On this computer readable means 1430, a computer program 1420c can be stored, which computer program 1420c can cause the processing circuitry 1310 and thereto operatively coupled entities and devices, such as the communications interface 1320 and the storage medium 1330, to execute methods according to embodiments described herein. The computer program 1420c and / or computer program product 1410c may thus provide means for performing any steps of the donor network node 1300 as herein disclosed.

[0150] In the example of Fig. 14, the computer program product 1410a, 1410b, 1410c is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 1410a, 1410b, 1410c could also be embodied as a memory, such as a random access memory (RAM), a readonly memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 1420a, 1420b, 1420c is here schematically shown as a track on the depicted optical disk, the computer program 1420a, 1420b, 1420c can be stored in any way which is suitable for the computer program product 1410a, 1410b, 1410c.

[0151] The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1. A method for connecting a radio unit (112) to a baseband node (130), wherein the method is performed by a radio network node (110), wherein the radio network node (110) comprises a mobile termination, MT, interface (114) and hosts the radio unit (112), and wherein the method comprises: establishing (S102) a wireless connection between the MT interface (114) and a user plane function, UPF, of a donor network node (120); connecting (S104) to the baseband node (130) paired with the radio unit (112) upon providing information about capabilities of the radio unit (112) and parameters of the wireless connection to a server device (190), and upon obtaining information from the server device (190) about the baseband node (130); and transporting (S112) fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and the UPF of the donor network node (120).

2. The method according to claim 1, wherein establishing the wireless connection comprises: sending (S102-2) an RRCSetupComplete message to the donor network node (120), wherein the RRCSetupComplete message comprises information that the MT interface (114) is used for transporting fronthaul traffic to and from the radio unit (112).

3. The method according to claim 2, wherein the information is comprised in a non-access stratum, NAS, message carried by the RRCSetupComplete message.

4. The method according to any preceding claim, wherein establishing the wireless connection comprises: requesting (S102-4) Internet Protocol, IP, addresses from the UPF; receiving (S102-6) a set of IP addresses from the UPF; and assigning (S102-8) at least one of the IP addresses to the radio unit (112).

5. The method according to any preceding claim, wherein the capabilities of the radio unit (112) comprise information of supported fronthaul interfaces, supported communication capabilities, and supported communication protocols of the radio unit (112).

6. The method according to claim 5, wherein the method further comprises: receiving (S106) information from the server device (190) about a type of fronthaul interface to be used for transporting the fronthaul traffic between the radio unit (112) and the baseband node (130).

7. The method according to any preceding claim, wherein the information provided to the server device (190) further comprises identity information of the radio unit (112).

8. The method according to any preceding claim, wherein the information from the server device (190) about the baseband node (130) comprises an Internet Protocol, IP, address of the baseband node (130), and wherein the fronthaul traffic is addressed to the IP address of the baseband node (130).

9. The method according to any preceding claim, wherein the method further comprises: receiving (S108) configuration data of the radio unit (112) from the baseband node (130), wherein the configuration data is to be used by the radio unit (112) when transporting fronthaul traffic between the radio unit (112) and the baseband node (130); and configuring (S110) the radio unit (112) with the configuration data.

10. The method according to any preceding claim, wherein the radio network node (110) is a child network node with respect to the donor network node (120).11 . The method according to any preceding claim, wherein the wireless connection is over a New Radio, NR, air interface or a Long Term Evolution, LTE, air interface between the MT interface (114) and the donor network node (120).

12. A method for selecting a baseband node (130) for a radio unit (112), wherein the method is performed by a server device (190), and wherein the method comprises: receiving (S202) information from a radio network node (110) hosting the radio unit (112) about capabilities of the radio unit (112) and parameters of a wireless connection established between a mobile termination, MT, interface (114) of the radio network node (110) and a donor network node (120), wherein the wireless connection is to be used for transporting fronthaul traffic between the radio unit (112) and the baseband node (130); selecting (S204) the baseband node (130) from a set of baseband nodes (130) based on the capabilities of the radio unit (112) and the parameters of a wireless connection; and sending (S206) information to the radio network node (110) about the selected baseband node (130).

13. The method according to claim 12, wherein the capabilities of the radio unit (112) comprise information of supported fronthaul interfaces, supported communication capabilities, and supported communication protocols of the radio unit (112).

14. The method according to claim 12 or 13, wherein the server device (190) has access to information of capacities and capabilities of the set of baseband nodes (130), and wherein the baseband node (130) further is selected based on the capacities and capabilities of the set of baseband nodes (130).

15. The method according to claim 13 and 14, wherein the method further comprises: selecting (S208) a type of fronthaul interface to be used for transporting the fronthaul traffic between the radio unit (112) and the baseband node (130) based on the information of supported fronthaul interfaces of the radio unit (112) and based on capacities and capabilities of the selected baseband node (130); and sending (S210) information to the radio network node (110) about the selected type of fronthaul interface.

16. The method according to any of claims 12 to 15, wherein the information received from the radio network node (110) further comprises and IP address of the radio unit (112), and wherein the method further comprises: sending (S212) the IP address of the radio unit (112) to the selected baseband node (130).

17. The method according to any of claims 12 to 16, wherein the information about the selected baseband node (130) comprises an Internet Protocol, IP, address of the selected baseband node (130).

18. A method for connecting a radio unit (112) to a baseband node (130), wherein the method is performed by a donor network node (120), and wherein the method comprises: establishing (S302) a wireless connection between the donor network node (120) and a mobile termination, MT, interface (114) of a radio network node (110) that hosts the radio unit (112); and transporting (S306) fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and a user plane function, UPF, of the donor network node (120), thereby connecting the radio unit (112) to the baseband node (130).

19. The method according to claim 18, wherein establishing the wireless connection comprises: receiving (S302-2) an RRCSetupComplete message from the radio network node (110), wherein the RRCSetupComplete message comprises information that the MT interface (114) is used for transporting fronthaul traffic to and from the radio unit (112).

20. The method according to claim 19, wherein the information is comprised in a non-access stratum, NAS, message carried by the RRCSetupComplete message.

21. The method according to claim 19 or 20, wherein the method further comprises:selecting (S304) an access and mobility management function, AMF, for the radio network node (110) based on the information that the MT interface (114) is used for transporting fronthaul traffic to and from the radio unit (112).

22. The method according to any of claims 18 to 21, wherein the radio network node (110) is a first radio network node (110), and wherein the method further comprises: establishing (S308) a wireless backhaul connection between the donor network node (120) and a second radio network node (150); and transporting (S310) backhaul traffic of the second radio network node (150) between the second radio network node (150) and a core network node and on the wireless backhaul connection.

23. The method according to claim 22, wherein the fronthaul traffic is transported on a first radio bearer, wherein the backhaul traffic is transported on a second radio bearer, and wherein the donor network node (120) serves at least one user equipment, U E, on a third radio bearer.

24. The method according to claim 22 or 23, wherein the UPF is hosted by the donor network node (120), wherein the UPF is a first UPF, wherein the donor network node (120) further hosts a second UPF, and wherein the fronthaul traffic is transported between the second radio network node (150) and the second UPF.

25. The method according to any of claims 18 to 24, wherein the wireless connection is over a New Radio, NR, air interface or a Long Term Evolution, LTE, air interface between the donor network node (120) and the MT interface (114).

26. A radio network node (110) for connecting a radio unit (112) to a baseband node (130), wherein the radio network node (110) comprises a mobile termination, MT, interface (114) and hosts the radio unit (112), the radio network node (110) comprising processing circuitry (1110), the processing circuitry being configured to cause the radio network node (110) to: establish a wireless connection between the MT interface (114) and a user plane function, UPF, of a donor network node (120); connect to the baseband node (130) paired with the radio unit (112) upon providing information about capabilities of the radio unit (112) and parameters of the wireless connection to a server device (190), and upon obtaining information from the server device (190) about the baseband node (130); and transport fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and the UPF of the donor network node (120).

27. The radio network node (110) according to claim 26, wherein the processing circuitry further is configured to cause the radio network node (110) to perform a method according to any of claims 2 to 11 .

28. A server device (190) for selecting a baseband node (130) for a radio unit (112), the server device (190) comprising processing circuitry (1210), the processing circuitry being configured to cause the server device (190) to: receive information from a radio network node (110) hosting the radio unit (112) about capabilities of the radio unit (112) and parameters of a wireless connection established between a mobile termination, MT, interface (114) of the radio network node (110) and a donor network node (120), wherein the wireless connection is to be used for transporting fronthaul traffic between the radio unit (112) and the baseband node (130); select the baseband node (130) from a set of baseband nodes (130) based on the capabilities of the radio unit (112) and the parameters of a wireless connection; and send information to the radio network node (110) about the selected baseband node (130).

29. The server device (190) according to claim 28, wherein the processing circuitry further is configured to cause the server device (190) to perform a method according to any of claims 13 to 17.

30. A donor network node (120) for connecting a radio unit (112) to a baseband node (130), the donor network node (120) comprising processing circuitry (1310), the processing circuitry being configured to cause the donor network node (120) to: establish a wireless connection between the donor network node (120) and a mobile termination, MT, interface (114) of a radio network node (110) that hosts the radio unit (112); and transport fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and a user plane function, UPF, of the donor network node (120), thereby connecting the radio unit (112) to the baseband node (130).31 . The donor network node (120) according to claim 30, wherein the processing circuitry further is configured to cause the server device (190) to perform a method according to any of claims 19 to 25.

32. A computer program (1420a) for connecting a radio unit (112) to a baseband node (130), the computer program comprising computer code which, when run on processing circuitry (1110) of a radio network node (110), wherein the radio network node (110) comprises a mobile termination, MT, interface (114) and hosts the radio unit (112), causes the radio network node (110) to: establish (S102) a wireless connection between the MT interface (114) and a user plane function, UPF, of a donor network node (120);connect (S104) to the baseband node (130) paired with the radio unit (112) upon providing information about capabilities of the radio unit (112) and parameters of the wireless connection to a server device (190), and upon obtaining information from the server device (190) about the baseband node (130); and transport (S112) fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and the UPF of the donor network node (120).

33. A computer program (1420b) for selecting a baseband node (130) for a radio unit (112), the computer program comprising computer code which, when run on processing circuitry (1210) of a server device (190), causes the server device (190) to: receive (S202) information from a radio network node (110) hosting the radio unit (112) about capabilities of the radio unit (112) and parameters of a wireless connection established between a mobile termination, MT, interface (114) of the radio network node (110) and a donor network node (120), wherein the wireless connection is to be used for transporting fronthaul traffic between the radio unit (112) and the baseband node (130); select (S204) the baseband node (130) from a set of baseband nodes (130) based on the capabilities of the radio unit (112) and the parameters of a wireless connection; and send (S206) information to the radio network node (110) about the selected baseband node (130).

34. A computer program (1420c) for connecting a radio unit (112) to a baseband node (130), the computer program comprising computer code which, when run on processing circuitry (1310) of a donor network node (120), causes the donor network node (120) to: establish (S302) a wireless connection between the donor network node (120) and a mobile termination, MT, interface (114) of a radio network node (110) that hosts the radio unit (112); and transport (S306) fronthaul traffic between the radio unit (112) and the baseband node (130) over the wireless connection, and in a protocol data unit, PDU, session between the MT interface (114) and a user plane function, UPF, of the donor network node (120), thereby connecting the radio unit (112) to the baseband node (130).

35. A computer program product (1410a, 1410b, 1410c) comprising a computer program (1420a, 1420b, 1420c) according to at least one of claims 32, 33 and 34, and a computer readable storage medium (1430) on which the computer program is stored.

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