Split architecture communication network

Abstract

A base station may have multiple entities such as a control plane apparatus and a distributed apparatus. The distributed apparatus provides radio coverage to user equipment via at least one cell and handles a physical layer of a radio protocol stack of the base station, while the control plane apparatus handles a radio resource control layer of the radio protocol stack of the base station. The base station is configured so that the distributed apparatus sends information regarding its characteristics or capabilities in an unsolicited message to the control plane apparatus. This allows the control plane apparatus to assign to the distributed apparatus and to the user equipment, a physical layer configuration required for communication between the user equipment and the distributed apparatus in response to a user equipment service request using the capabilities information and information in the service request.

Description

[0001] SPLIT ARCHITECTURE COMMUNICATION NETWORK

[0002] TECHNOLOGICAL FIELD

[0003] Various example embodiments relate to radio communication networks where logical functions and responsibilities are split between multiple entities that form a base station.

[0004] BACKGROUND

[0005] In modern radio communication network architecture such as in 5G, base stations may be formed of several entities each configured to handle different logical functions and responsibilities. These entities or nodes may comprise a central unit CU, which may host the higher radio protocol stack layers and in some cases be located in the cloud and distributed units DU which may host the lower layer radio protocol stack and which provide radio coverage via cells. A CU may manage multiple DUs which can lead to hardware efficiencies. A potential drawback is that signalling between the entities may increase latency.

[0006] BRIEF SUMMARY

[0007] The scope of protection sought for various example embodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0008] According to various, but not necessarily all, example embodiments of the disclosure there is provided a control plane apparatus of a base station comprising: at least one processor; and at least one memory storing instructions that when executed by said at least one processor cause said control plane apparatus at least to perform: receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being configured to provide radio coverage to user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus is configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; storing said configuration characteristics in said at least one memory of said control plane apparatus; in response to receipt of a service request from the user equipment, retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

[0009] In some example embodiments, the control plane apparatus is caused to perform said step of receiving configuration characteristics from the distributed apparatus prior to receiving the service request from the user equipment.

[0010] In some example embodiments, the physical layer configurations comprise layer 1 and layer 2 configurations.

[0011] In some example embodiments, the assigned configurations comprise all resources required for the UE distributed apparatus communication.

[0012] In some example embodiments, said configuration characteristics comprise an indication of radio resources available to said distributed apparatus.

[0013] In some example embodiments, said step of assigning said physical layer configuration comprises selecting radio resources for communication between the distributed apparatus and the user equipment from said radio resources indicated as being currently available to said distributed apparatus by said stored configuration characteristics.

[0014] In some example embodiments, said control plane apparatus is further caused to update said at least one memory storing said configuration characteristics based on allocated resources of said distributed apparatus.

[0015] In some example embodiments, said configuration characteristics are received during a network setup procedure.

[0016] In some example embodiments, said configuration characteristics are received as an unsolicited message.

[0017] In some example embodiments, said network setup procedure, comprises a procedure performed when setting up the network or a procedure performed when configuring an interface or a procedure performed during an interface configuration update. In some example embodiments, said control plane apparatus is caused in response to receipt of a further user equipment service request, to determine whether there is configuration information stored in said at least one memory for a distributed apparatus being configured to provide radio coverage to said further user equipment; and where so: to retrieve said information regarding configuration characteristics of said distributed apparatus and to assign at least a physical layer configuration required for communication between said further user equipment and said distributed apparatus in dependence upon said configuration characteristics and said user equipment service request; and where not: to generate a message for transmission to the distributed apparatus requesting configuration information from said distributed apparatus.

[0018] In some example embodiments, said control plane apparatus being further caused to perform: causing transmission of an indication of said assigned physical layer configuration to said distributed apparatus.

[0019] In some example embodiments, said transmission is sent as a distributed apparatus configuration command.

[0020] In some example embodiments, said control plane apparatus is further caused to perform: causing transmission of an indication of said assigned physical layer configuration to said user equipment.

[0021] In some example embodiments, said transmission is sent as a radio resource control RRC set up signal.

[0022] In some example embodiments, said transmission is sent transparently via the distributed apparatus

[0023] In some example embodiments, said at least one memory is configured to store configuration characteristics of a plurality of distributed apparatuses each being configured to provide radio coverage via at least one cell.

[0024] In some example embodiments, said control plane apparatus is further caused to select a distributed apparatus for providing radio coverage for said user equipment and to retrieve from said data store information regarding configuration characteristics of said selected distributed apparatus for use in said assigning of said physical layer configuration.

[0025] In some example embodiments, said assigned physical layer configuration associates the distributed apparatus with the endpoint of a radio resource bearer.

[0026] In some example embodiments, said assigned physical layer configuration includes a transport network layer TNL address.

[0027] In some example embodiments, said assigning of said physical layer configuration comprises allocating an IP tunnel for radio bearers from TNL to the radio network layer RNL.

[0028] In some example embodiments, said control plane apparatus comprises a gNB-Cll node.

[0029] In some example embodiments, said control plane apparatus comprises a gNB-CU-CP node.

[0030] In some example embodiments, said control plane apparatus is configured to host the control plane part of the packet data convergence protocol PDCP, the base station comprising a corresponding user plane control apparatus configured to host the user plane part of the PDCP protocol.

[0031] In some example embodiments, said user plane control apparatus comprises a gNB- CU-UP node.

[0032] In some example embodiments, said control plane apparatus is further caused to transmit said TNL address to said corresponding user plane control apparatus.

[0033] According to various, but not necessarily all, example embodiments of the disclosure there is provided a control plane apparatus of a base station, the control plane apparatus comprising: means for receiving signals from a distributed apparatus of the base station; means for storing data; and means for assigning resources; wherein said means for receiving is for receiving from the distributed apparatus of the base station, configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, wherein said distributed apparatus is configured to provide radio coverage to user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus is configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; said means for storing is for storing said configuration characteristics of said control plane apparatus; and wherein in response to receipt of a service request from the user equipment, said means for assigning retrieves from said at least one memory information regarding configuration characteristics of said distributed apparatus and assigns, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

[0034] In some example embodiments said apparatus may further comprise one or more of a means for transmitting, means for updating said means for storing, means for generating messages, and means for selecting a distributed apparatus.

[0035] The means may perform the optional features set out in relation to the apparatus mentioned above.

[0036] According to various, but not necessarily all, example embodiments of the disclosure there is provided a control plane apparatus of a base station, the control plane apparatus comprising: circuitry configured to perform receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being configured to provide radio coverage to user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; circuitry configured to perform storing said configuration characteristics in said at least one memory of said control plane apparatus; circuitry configured to perform receiving a service request from a user equipment; circuitry configured to perform retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and circuitry configured to perform assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

[0037] The circuitry may be configured to perform the optional features set out in relation to the apparatus mentioned above.

[0038] According to various, but not necessarily all, example embodiments of the disclosure there is provided a method performed at a control plane apparatus of a base station, said method comprising: receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus providing radio coverage to user equipment via at least one cell, wherein said distributed apparatus handles at least a physical layer of a radio protocol stack of the base station and said control plane apparatus handles at least a part of a radio resource control layer of the radio protocol stack of the base station; storing said configuration characteristics in said at least one memory of said control plane apparatus; receiving a service request from a user equipment; retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

[0039] In some example embodiments, said method further comprises: in response to receipt of a further user equipment service request, to determine whether there is configuration information stored in said at least one memory for a distributed apparatus providing radio coverage to said further user equipment; and where so: to retrieve said information regarding configuration characteristics of said distributed apparatus and to assign at least a physical layer configuration required for communication between said further user equipment and said distributed apparatus in dependence upon said configuration characteristics and said user equipment service request; and where not: to generate a message for transmission to the distributed apparatus requesting configuration information from said distributed apparatus. In some example embodiments, said method performs said step of receiving configuration characteristics from the distributed apparatus prior to receiving the service request from the user equipment.

[0040] In some example embodiments, said step of assigning said physical layer configuration comprises selecting radio resources for communication between the distributed apparatus and the user equipment from said radio resources indicated as being currently available to said distributed apparatus by said stored configuration characteristics.

[0041] In some example embodiments, said method further comprises: updating said at least one memory storing said configuration characteristics based on allocated resources of said distributed apparatus.

[0042] In some example embodiments, said method further comprises: causing transmission of an indication of said assigned physical layer configuration to said distributed apparatus.

[0043] In some example embodiments, said method further comprises: causing transmission of an indication of said assigned physical layer configuration to said user equipment.

[0044] In some example embodiments, said method comprises storing configuration characteristics of a plurality of distributed apparatuses each providing radio coverage via at least one cell.

[0045] In some example embodiments, said method further comprises: selecting a distributed apparatus for providing radio coverage for said user equipment and retrieving from said data store information regarding configuration characteristics of said selected distributed apparatus for use in said assigning of said physical layer configuration.

[0046] In some example embodiments, said step of assigning of said physical layer configuration comprises allocating an IP tunnel for radio bearers from TNL to the radio network layer RNL.

[0047] In some example embodiments, said method further comprises transmitting said TNL address to said corresponding user plane control apparatus.

[0048] According to various, but not necessarily all, example embodiments of the disclosure there is provided a computer program comprising computer readable instructions which when executed by a processor on a control plane apparatus of a base station are operable to control said control plane apparatus to: receive, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being for providing radio coverage to the user equipment via at least one cell and for handling at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; store said configuration characteristics; in response to receipt of a service request from the user equipment, retrieve information regarding configuration characteristics of said distributed apparatus; and assign, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

[0049] The computer program may be for causing performance of the optional steps set out in relation to the method mentioned above.

[0050] According to various, but not necessarily all, example embodiments of the disclosure there is provided a non-transitory computer readable medium comprising program instructions stored thereon for causing a control plane apparatus of a base station to perform at least the following: receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; storing said configuration characteristics in said at least one memory of said control plane apparatus; receiving a service request from a user equipment; retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request. The instructions may be for performing the optional features set out in relation to the method mentioned above.

[0051] According to various, but not necessarily all, example embodiments of the disclosure there is provided a distributed apparatus of a base station, said distributed apparatus comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the distributed apparatus at least to perform: generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus of the base station, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus is configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; causing transmission of said message to said control plane apparatus.

[0052] In some example embodiments, said message generated by said distributed apparatus comprises configuration characteristics of said distributed apparatus, said configuration characteristics comprising information required for physical layer configuration for said communication between said distributed apparatus and said user equipment.

[0053] In some example embodiments, said configuration characteristics comprise information indicative of radio resources available to said distributed apparatus.

[0054] In some example embodiments, said configuration characteristics comprise an indication of at least one of: physical uplink shared channel PLISCH resources, random access channel RACH configurations, or a range of cell network temporary identifiers C-RNTIs, and additionally at least some further assistance information; wherein said further assistance information comprises: capability indicators indicating support for particular functions, explicit configuration of radio resources, frequency capabilities, frequency band(s), Bandwidth Part, Bandwidth capabilities, channel capabilities, cell information, cell identifiers, beams configuration, synchronisation signal block SSB, channel state information reference signal CSI-RS, scheduling capabilities such as maximum number of simultaneously supported UEs, timing restrictions, measurement gaps information, cell Group Config, Reference signal config, time domain table, cell-specific operations, HW information such as antennas configurations, carrier aggregation support, native carrier aggregation, (de)modulation mode, maximum capabilities. In some example embodiments, said distributed apparatus is caused to transmit said configuration characteristics during a network setup procedure.

[0055] In some example embodiments, said network setup procedure comprises a procedure performed when setting up the network or a procedure performed when configuring an interface or a procedure performed during an interface configuration update.

[0056] In some example embodiments, said transmission of said configuration characteristics is an unsolicited transmission.

[0057] In some example embodiments, said distributed apparatus is caused to transmit said configuration characteristics independently of any user equipment service requests.

[0058] In some example embodiments, said distributed apparatus is configured to transmit said configuration characteristics as a notification message - not requiring an ack.

[0059] In some example embodiments, said apparatus is further caused to: receive a network configuration command from said control plane apparatus, the command comprising at least a physical layer configuration required for communication between said user equipment and said distributed apparatus; configure resources based on said network configuration command; and communicate with said user equipment using said configured resources.

[0060] According to various, but not necessarily all, example embodiments of the disclosure there is provided a distributed apparatus of a base station, said distributed apparatus comprising: means for generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus of the base station, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell, and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; means for transmitting said message to said control plane apparatus.

[0061] In some example embodiments, said distributed apparatus further comprises means for receiving a network configuration command from said control plane apparatus, the command comprising at least a physical layer configuration required for communication between said user equipment and said distributed apparatus; means for configuring resources based on said network configuration command; and means for communicating with said user equipment using said configured resources.

[0062] The means may perform the optional features set out in relation to the apparatus mentioned above.

[0063] According to various, but not necessarily all, example embodiments of the disclosure there is provided a distributed apparatus of a base station, said distributed apparatus comprising: circuitry configured to perform generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus of the base station, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; circuitry configured to perform transmitting said message to said control plane apparatus.

[0064] In some example embodiments, said distributed apparatus further comprises circuitry configured to perform: receiving a network configuration command from said control plane apparatus, the command comprising at least a physical layer configuration required for communication between said user equipment and said distributed apparatus; circuitry configured to perform configuring resources based on said network configuration command; and circuitry configured to perform communicating with said user equipment using said configured resources.

[0065] The circuitry may be configured to perform the optional features set out in relation to the apparatus mentioned above.

[0066] According to various, but not necessarily all, example embodiments of the disclosure there is provided a method performed at a distributed apparatus of a base station, the distributed apparatus providing radio coverage to a user equipment via at least one cell, and handling at least a physical layer of a radio protocol stack while a control plane apparatus of the base station handles at least a part of a radio resource control layer of the radio protocol stack, said method comprising: generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus; transmitting said message to said control plane apparatus.

[0067] In some example embodiments, said method further comprises: receiving a network configuration command from said control plane apparatus; configuring resources indicated by said network configuration command; and transmitting a message to said user equipment using said configured resources.

[0068] According to various, but not necessarily all, example embodiments of the disclosure there is provided a computer program comprising computer readable instructions which when executed by a processor on a distributed apparatus of a base station, the distributed apparatus being configured to provide radio coverage to a user equipment via at least one cell, and to handle at least a physical layer of a radio protocol stack while a control plane apparatus of the base station is configured to handle at least a part of a radio resource control layer of the radio protocol stack, are operable to control said distributed apparatus to: generate a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus; transmit said message to said control plane apparatus; and provide radio coverage to the user equipment via at least one cell.

[0069] The computer program may be for causing performance of the optional steps set out in relation to the method mentioned above.

[0070] According to various, but not necessarily all, example embodiments of the disclosure there is provided a non-transitory computer readable medium comprising program instructions stored thereon for causing a distributed apparatus of a base station, the distributed apparatus being configured to provide radio coverage to a user equipment via at least one cell, and to handle at least a physical layer of a radio protocol stack while a control plane apparatus of the base station is configured to handle at least a part of a radio resource control layer of the radio protocol stack, to perform at least the following: generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus; transmitting said message to said control plane apparatus.

[0071] The instructions may be for performing the optional features set out in relation to the method mentioned above. According to various, but not necessarily all, example embodiments of the disclosure there is provided user plane apparatus of a base station, said user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station; comprising: at least one processor; and at least one memory storing instructions that when executed by said at least one processor cause said user plane apparatus at least to perform: receiving a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus handling at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and based on said bearer context request and said TNL address, setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

[0072] In some example embodiments, the user plane apparatus is further caused to perform: transmission of an indication that said bearer context setup is performed as a bearer context setup response.

[0073] According to various, but not necessarily all, example embodiments of the disclosure there is provided a user plane apparatus of a base station being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, the user plane apparatus comprising: means for receiving a bearer context setup request from a control plane apparatus of the base station, said bearer context set up request comprising a transport network layer TNL address; and means for setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station based on said bearer context request and said TNL address.

[0074] The means may perform the optional features set out in relation to the apparatus mentioned above.

[0075] According to various, but not necessarily all, example embodiments of the disclosure there is provided a user plane apparatus of a base station, the user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, the user plane apparatus comprising: circuitry configured to perform receiving a bearer context setup request from a control plane apparatus of the base station, said bearer context set up request comprising a transport network layer TNL address; and circuitry configured to perform setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station based on said bearer context request.

[0076] The circuitry may be configured to perform the optional features set out in relation to the apparatus mentioned above.

[0077] According to various, but not necessarily all, example embodiments of the disclosure there is provided a method performed at a user plane apparatus of a base station the user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, said method comprising: receiving a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus handling at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and, based on said bearer context request, setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

[0078] In some example embodiments, the method further comprises transmitting an indication that said bearer context setup is performed as a bearer context setup response.

[0079] According to various, but not necessarily all, example embodiments of the disclosure there is provided a computer program comprising computer readable instructions which when executed by a processor on a user plane apparatus of a base station the user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, are operable to control said user plane apparatus to: receive a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus handling at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and, based on said bearer context request, set up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

[0080] The computer program may be for causing performance of the optional steps set out in relation to the method mentioned above.

[0081] According to various, but not necessarily all, example embodiments of the disclosure there is provided a non-transitory computer readable medium comprising program instructions stored thereon for causing a user plane apparatus of a base station the user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, to perform at least the following: receiving a bearer context setup request from a control plane apparatus of the base station, said bearer context set up request comprising a transport network layer TNL address; and, based on said bearer context request, setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

[0082] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0083] The instructions may be for performing the optional features set out in relation to the method mentioned above.

[0084] Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.

[0085] BRIEF DESCRIPTION

[0086] Some example embodiments will now be described with reference to the accompanying drawings in which:

[0087] FIG. 1 illustrates an initial access procedure involving E1 and F1 signalling according to the prior art;

[0088] Fig. 2 schematically illustrates different entities and signalling between entities in a distributed 6G network according to an embodiment;

[0089] Fig. 3 schematically illustrates the signalling of DU capabilities according to an embodiment;

[0090] Fig. 4 schematically illustrates the signalling of DU capabilities according to an embodiment having multiple Dus under one CU;

[0091] Fig. 5 schematically illustrates the signalling of updated DU capabilities according to an embodiment;

[0092] Fig. 6 schematically illustrates DU configuration following UE service request according to an embodiment;

[0093] Fig. 7 schematically illustrates the bearer context setup according to an embodiment; and Fig. 8 schematically illustrates simplified bearer modification with DU configuration command embedded with RRC configuration sent to the UE.

[0094] DETAILED DESCRIPTION

[0095] Before discussing the example embodiments in any more detail, first an overview will be provided.

[0096] Latency is one of the key KPIs (key performance indicators) for 5G and is envisioned to be even more strict for 6G technology. In 5G network architecture there is an NG-RAN split in context of logical functions and responsibilities, CU (central unit) tasks (configuring higher layers) and DU (distributed unit) tasks (configuring lower layers) are performed at separate entities. Thus, a single UE request (and configuration) is not possible to be processed without several messages being exchanged back and forth between involved NG-RAN entities (CU and DU). The DU, as the distributed entity, by definition and function is the Network Entity to which the UE sends the message. It is, however, not able to understand the message and identity the UE (because it does not host the RRC protocol). It can blindly forward the message to the CU. The CU after processing the message needs to receive information from the DU regarding the configuration of the lower layers so as to be able to construct a response message for the UE. This protocol and functional split increases latency as all requests require some input from both CU and DU before being finally delivered to the UE.

[0097] It is proposed to provide coordination between the network’s logical entities that share control of lower and higher layer resources. The procedure proposes sharing the lower layer network entity’s (DU) configuration characteristics or capabilities with its associated higher layer network entity (CU) to thereby reduce the time required for synchronization of the lower layer capabilities and available resources. In particular, the DU may independently and without waiting for a UE connection or service request generate and transmit a ‘capability message’ providing information on the DU’s supported functionalities and available radio resources. This allows the CU to allocate radio resources in response to receipt of a user equipment service request and to configure the DU and UE without the need to exchange information with the DU first. This reduces the amount of signalling required and the latency of the procedure.

[0098] In effect the DU message provides an indication to the CU that the DU can be configured for communication with a user equipment by the CU. The message also provides the required information to allow this to happen. This information may include the radio resources available to the distributed apparatus prior to allocation of resources, so in effect an indication of the capabilities of the DU. The indication that the DU can be configured by the CU may be in the content of the message sent or in the format of the message. For example, the indication may be provided simply by receipt at the CU of an unsolicited message from the DU indicating configuration characteristics of the DU. The message may be received before receiving UE service request from the UE. Receipt of such an unsolicited message indicates to the CU that it may remotely or centrally configure the DU for communication with the UE.

[0099] The distributed apparatus DU may be configured to transmit said configuration characteristics as a notification message that does not require an ack.

[0100] The UE service request may be a connection request, or a communication service request related to a UE (e.g., bearer context setup / modification request).

[0101] By providing this information in advance, i.e. before receipt of the UE service request, the latency when responding to a UE service request is reduced as the message transfers between the CU and DU to negotiate suitable configuration is avoided or at least reduced.

[0102] Where there are separate user plane and control plane control entities then the DU providing these configuration characteristics may enable the control plane entity to configure the transport network layer without communicating with the DU.

[0103] In some embodiments, the DU provides the DU configuration characteristics or capabilities to the CU upon connection establishment to the CU (during setup) or it may do so during a network update procedure upon request during operation. The DU configuration characteristics may include amount of available resources and / or type of resources. In some embodiments, DU defines and provides a “default lower layer configuration” to CU.

[0104] The network update procedure may be in response to distributed apparatus having a software update, or waking from or entering a low power mode, or one or more of the following: frequency / cell shut down status or energy savings status change, frequency / cell sleep or waking up event, RF channel disablement, base band processor switching on or off. The configuration characteristics of the DU, that are sometimes referred to as DU capabilities in this disclosure, may include reference signal resources and reporting resources and allocation of UP addresses for the user plane, an indication of physical uplink shared channel PUSCH resources, random access channel RACH configurations, and a range of cell network temporary identifiers C-RNTIs and at least some further assistance information; wherein said further assistance information may comprise: capability indicators indicating support for particular functions, explicit configuration of radio resources, frequency capabilities, frequency band(s), Bandwidth Part, Bandwidth capabilities, channel capabilities, cell information, cell identifiers, beams configuration, synchronisation signal block SSB, channel state information reference signal CSI-RS, scheduling capabilities such as maximum number of simultaneously supported UEs, timing restrictions, measurement gaps information, cell Group Config, Reference signal config, time domain table, cell-specific operations, HW information such as antennas configurations, carrier aggregation support, native carrier aggregation, (de)modulation mode, maximum capabilities.

[0105] The CU maintains a data store comprising information on connected DUs and their DU configuration characteristics or capabilities and updates the stored available resources as resources are allocated. The CU allocates / reserves lower layer resources of DU from available resources and adds further higher layer / UE specific resources to generate a complete configuration for the UE and DU. The storage of this configuration information is an indication that the distributed apparatus is capable of remote or centralised configuration.

[0106] The distributed apparatus may be a distributed unit of a distributed apparatus gNB- DU.

[0107] The distributed apparatus may be configured to host physical layers or lower layers of the radio protocol stack. Lower layers may be layer 1 and in some cases layer 1 and layer 2.

[0108] The control plane apparatus may be configured to host layer 3 of the radio protocol stack.

[0109] The DU will provide the required configuration characteristic information / DU capabilities to the CU about its resources independently of any UE service request, these may include lower layer radio resources and transport network layer (TNL) resources and other resources that enable the CU to perform radio resources allocation and the allocation of TNL addresses for each UE service request “in one step”, ie. , without asking the DU for the information on lower layer radio and TNL resources. In effect the DU outsources bookkeeping of its radio, transport network resources to the CU, but double checks and executes the resource allocations / assignments.

[0110] Triggered by a communication service request related to a UE (eg., bearer context setup / modification request) received at the CU, the CU determines the affected DU and then allocates, assigns, determines resources of the affected DU (radio, transport layer) which are needed to support the communication service request of the UE and updates the bookkeeping of the DU resources in CU; CU relates those DU resources to the resources (higher layer radio) of the CU and generates a first configuration for the DU which it then transmits to the DU. This configuration command may include all assigned DU resources plus the related CU resources which are required to setup / modify the communication service of the UE between DU and CU and CNN; and generates a second configuration for the UE, including all assigned resources of the DU and CU to setup / modify the communication service of the UE between DU and CU and CNN.

[0111] In some embodiments, the CU may be split into CU-CP and CU-UP according to 5G RAN. In such embodiments the DU may inform the CU-CP of its configuration characteristics or capabilities and the CU-CP then may seek to share this information to align / synchronize with CU-UP to thereby reduce latency.

[0112] For example, the DL TNL address may be conveyed to the CU-UP / RAN-UP (from CU- CP via the E1 interface). DU and DL tunnel endpoint of DU are not known when CU-CP and CU-UP establish their connection; However, this address may be conveyed by the CU-CP without waiting for the DU to provide the same, because CU-CP introduces an association of the DL TNL address at the DU with the radio bearer ID.

[0113] In particular, for split architecture such as that seen for 6G RAN, embodiments provide:

[0114] A “DU capability message” that brings certain assistance information on available resources and supported functionalities to the CU. The assistance information is provided in advance before any service request from the UEs.

[0115] The information elements lEs in the DU capability message (i.e. the message carrying configuration characteristics) contain information from the DU on a cell-level that can be used by the CU for immediate configuration of the UE, once the service request from the UE arrives. This information serves as a “baseline” to allocate resources upon receipt of the service request from the UE. The CU manages the resource allocation by configuring the DU and the UE.

[0116] The DU capability message contains information which the CU can use for initial / baseline configuration for the UEs. This removes or at least reduces the need for fetching this information (via back-and-forth messages) for each UE arrival / service request as done previously and thereby should significantly improve the control plane latency.

[0117] Fig. 1 schematically illustrates signalling between the CU and DU nodes with the associated latency implications in a UE initial access procedure to a network. This involves both E1 (between CU-CP and CU-UP and F1 (between CUs and DUs) signalling.

[0118] As specified in TS38.401 , steps 9-15 define the transport layer address and needs gNB- CU-UP involvement and multiple signalling between CU-CP and CU -UP:

[0119] 9. The gNB-CU-CP sends the BEARER CONTEXT SETUP REQUEST message to establish the bearer context in the gNB-CU-UP.

[0120] 10 The gNB-CU-UP sends the BEARER CONTEXT SETUP RESPONSE message to the gNB-CU-CP, including F1-U UL TEID and transport layer address allocated by the gNB-CU-UP.

[0121] 11. The gNB-CU sends the UE CONTEXT SETUP REQUEST message to establish the UE context in the gNB-DU. In this message, it may also encapsulate the SecurityModeCommand message. In case of NG-RAN sharing, the gNB-CU includes the serving PLMN ID (for SNPNs the serving SNPN ID).

[0122] 12. The gNB-DU sends the SecurityModeCommand message to the UE.

[0123] 13. The gNB-DU sends the UE CONTEXT SETUP RESPONSE message to the gNB-CU.

[0124] 14. The gNB-CU-CP sends the BEARER CONTEXT MODIFICATION REQUEST message to the gNB-CU-UP, including F1-U DL TEID and transport layer address allocated by the gNB-DU.

[0125] 15. The gNB-CU-UP sends the BEARER CONTEXT MODIFICATION RESPONSE message to the gNB-CU-CP. [...]

[0126] As can be seen defining the transport layer address requires multiple signals to be sent between the CU-CP and CU-UP.

[0127] In one embodiment, see Fig. 2, the 6G RAN network node 20 comprises gNB-CU-CP 22, multiple gNB-CU-UP 24 and multiple gNB-DU 26A, 26B entities, where the CU entities host higher layers of the radio protocol stack, such as RRC, with all the related functions of the Control Plane and radio resources, and the DU hosts the lower layers protocol stack, such as PHY and MAC. The CU entity is responsible for Radio Resources allocation, UE 50 context management and communication with the Core Network 30.

[0128] In the split 6G RAN architecture, specific features of 6G CU contain:

[0129] Control Plane Configuration Management (RRC) and Radio Resource Management

[0130] The 6G DU function contains:

[0131] User Plane handling.

[0132] The internal network entities have an established interface (e.g., F1-type as in 5G) for the sake of communication between each other. 6G specific behaviour would be that the interface is used to exchange information on DU associated status and resources regardless of the UE status, to let the CU configure and manage Radio Resources configuration. Fig. 2 depicts an example of such a generic procedure:

[0133] In this embodiment the CU-CP comprises a data store 23 for storing DU capability or configuration characteristic data received from the DU. It also comprises radio resource allocation circuitry 21 , which may take the form of a processor, for allocating radio resources to a UE in response to a request and based on the relevant DU’s available resources determined from the data store 23.

[0134] The DUs 26 are configured to transmit DU configuration characteristic (e.g. including or also known as capability information) to the CU or where there is a split CU as in this case, to the CU-CP, which is then stored by the CU-CP 22 in data store 23. The DUs 26 may transmit this information without waiting for a UE service request, for example, they may do it during a network setup, or network update procedure.

[0135] In this way the CU or CU-CP 22 is notified about the DU 26 capabilities before any initiation from the UE 50, accelerating the process of replying to the UE when it does send an RRC Service Request.

[0136] Fig. 3 shows signalling between a UE 50, DU 26 and CU 25 where the CU is a single node not a node split into control plane and user plane entities.

[0137] The DU 26 signals its DU capabilities or configuration characteristics - signalling 31 and this may happen during or after Network setup without any users currently connected to the Network (e.g. UE in RRC IDLE state). If the CU 25 controls several Dlls 26, they can each provide their own capabilities in the initial phase of Network Setup, providing the CU with a complete setup of resources for all DUs under CU control (e.g. surrounding DUs or DUs in CU reach). The DU capability may be a one-directional message (accelerating the Network operations), or in some scenarios can be followed by the CU response in a form of DU configuration (of the DU layers, e.g., RLC, MAC, PHY). However, the response message to the DU can be deferred until there is any change in the resources required, usually based on a new service request from the UE signalling 32, whereupon the CU 25 performs the configuration and the configuration signal 34 is sent. In some embodiments, the DU capability may be queried by the CU, so that DU Capability is provided as a reply message to CU request message.

[0138] Fig. 4. shows a related embodiment with multiple DUs 26A - C under one CU 25. In this case each DU transmits its configuration characteristics or capabilities in signals, 41 , 42 and 43 during the DU setup procedure and this information is stored in a data store within CU 25. This information can then be used in response to receipt of UE service request for example to generate a configuration for communication between the DU and the UE at the CU.

[0139] Additionally and / or alternatively, the DU capability can be updated from the DU, if its resource status changes, see message 55 Fig. 5. In this embodiment, the DU capability or configuration characteristics are sent as an unsolicited message 51 from the DU to the CU and are stored at the CU. Then in response to a user service request 52 the CU configures the UE and DU using the stored DU capability information and sends a configuration command 53 to the DU and a RRC service setup to the UE 54. If there is later a change to the DU resource status, perhaps the DU has a software update, or the DU enters a different low or high power mode, then the DU may transmit a DU capability update message 55 to the CU allowing it to update its store information and to use the update information to configure the UE and DU in response to a UE service request.

[0140] Fig. 6. Shows DU configuration upon UE Service Request 62.

[0141] The radio resources allocation and configuration performed in the CU entity are based on the provided DU capabilities or configuration characteristics 61 , that are provided before the UE service request in message 62. The format of the DU capabilities or configuration characteristics assumes information elements that provides overall radio resources of the DU: required for L1 and L2 configuration:

[0142] PUSCH resources, RACH configurations (Random Access preambles, set or range of preambles), range of C-RNTIs, other set of assistance information (such as capability bits on support for particular functions), or explicit configuration of radio resources (such as a list of parameters with their values),

[0143] Frequency capabilities, frequency band(s), Bandwidth Part, Bandwidth capabilities, channel capabilities, cell information, cell identifiers, beams configuration, SSB, CSI-RS, scheduling capabilities like maximum number of simultaneously supported UEs, timing restrictions, measurement gaps information, cell Group Config, Reference signal config, time domain table, cell-specific operations, HW information such as antennas configurations, carrier aggregation support, native carrier aggregation, (de)modulation mode, maximum capabilities, etc.

[0144] The DU capabilities or configuration characteristics are further stored in the CU and used to build content of a reply message:

[0145] 1. To the DUs 63, 63a, 63b a. The DU configuration: o Set of RRC configurations built based on the assistance information provided in the DU capability.

[0146] 2. To the UE 64, 64a, 64b a. User specific RRC configuration, e.g.:

[0147] (L1 / L2 configurations, cell information, cell identifiers, beams configuration, SSB, CSI-RS, scheduling capabilities like maximum number of simultaneously supported UEs, timing restrictions, measurement gaps information, cell Group Config, Reference signal config, time domain table, cell-specific operation).

[0148] It is assumed that, in contrast to 5G, the DU conveys certain “capabilities / information” or configuration characteristics to the CU before any UE service request. With this concept of a “light DU” in 6G, with the DU being responsible for lower layer and user plane handling, it is assumed that the DU will provide the required information to the CU about its resources to enable the CU to perform radio resources allocation and the allocation of TNL addresses for each UE service request, without asking the DU for the information. After radio bearer setup (or addition) request for the UE, the CU configures the DU and UE with configurations associated in two domains: the RNL and the TNL as shown in Fig. 7

[0149] The method proposed can also apply in a 6G RAN split architecture (Fig. 2 and 8), which inherits the 5G RAN split i.e. , the RAN node is split into CLI-CP, CU-LIP and DU nodes. The network interfaces may be the same as in 5G (i.e., the NG, the E1 , and the F1 interfaces. Also in this case, it is assumed that the DU will provide the above-mentioned information to the CU on its resources before any UE service request. In such a deployment, that, in particular, can be expected during migration from 5G to 6G networks, the method can still apply with a modification. In more detail, the DL TNL address needs to be conveyed to the CU-UP / RAN-UP over the E1 interface. However, this address is conveyed by the CU-CP without waiting for the DU to provide the same. This involves changes in messages for the association of the DU TNL address with the radio bearer ID.

[0150] The detailed procedure for allocating session address to a radio bearer identifier can have the following steps as shown in Fig. 8:

[0151] 1. When UE context setup or modification is triggered (e.g., due to setup or addition of PDU session), the Network Entity that hosts Control Plane (e.g., RAN CU or gNB-CU- CP) needs to establish a bearer context in TNL and RNL for the UE. a. The trigger implies that the CU makes the association by allocating radio resources (at DU) to the requested session address; b. The CU generates the DU configuration and the UE configuration;

[0152] 2. The RAN CU or gNB-CU-CP can communicate in this phase the bearer DL TNL address in a message towards the RAN Network entity supporting user plane handling (RAN DU); a. For simplistic architecture (RAN split to DU and CU) this implies assignment of radio bearer ID and association to DU TNL address in RAN CU; b. Alternatively, for architecture with reuse of 5G interfaces and messages, the gNB-CU-CP sends the BEARER CONTEXT SETUP REQUEST to gNB-CU-UP. Even though, the messaging is not avoided, the gNB-CU-CP can communicate already in this phase the bearer DL TNL address as the outcome of the association. BEARER CONTEXT SETUP REQUEST and RESPONSE to and from gNB-CU-UP is to allocate the endpoint for a radio bearer that is setup, instead of requesting and awaiting the address (as in 5G);

[0153] 3. DU CONFIGURATION message is sent from CU to DU with DL TNL address as the Information Element in the message; a. If the RAN CU hosts RRC it can send the message directly to the UE (without embedded RRC configuration to the DU to be passed to the UE) (as in Fig. 7)

[0154] 4. Alternatively (as in Fig. 8), the UE CONTEXT MODIFICATION COMMAND including the DU CONFIGURATION (with TNL address) and the RRC reconfiguration message for the UE with new bearer configuration (with bearer id) is sent to the gNB-DU from the gNB-CU-CP; a. The gNB-DU does not need to acknowledge the configuration (as received in DU CONFIGURATION), which accelerates the establishment of the overall connection . The acknowledgment may come later with a UE reply to RRC Reconfiguration message, after the bearer context is established in the E2E perspective.

[0155] 5. RRC configuration with associated radio bearer ID for the UE is sent to the UE.

[0156] 6. In architecture reusing 5G procedures and interfaces, UL RRC MESSAGE TRANSFER including RRC reconfiguration complete is forwarded by the gNB-DU to the CU

[0157] 7. RRC reconfiguration complete from the UE confirms the allocation of the tunnel in RNL; a. Alternatively, UL RRC MESSAGE TRANSFER including RRC reconfiguration complete confirms the allocation of the tunnel in TNL

[0158] Embodiments may provide a solution that maximizes or at least increases reuse of the 5G split architecture (by keeping the same logical split, protocol layers in CU and DU as in 5G, responsibility in the CU to handle the UE configuration) but reduces connection delays. It may reduce DU responsibility, minimize or at least reduce its interaction at service setup and simplify the F1 interface.

[0159] In a conventional split architecture system, a single UE request in UL may not be able to be processed without several messages being exchanged back and forth between involved NG-RAN entities (CU and DU). DU, as the distributed entity, by definition and function is the Network Entity to which the UE sends the message. The DU is not, however, able to understand the message and identity the UE (because it does not host RRC protocol). It can blindly forward the message to the CU-CP. The CU-CP after processing the message needs to receive the information from the DU on lower layers configuration to construct a response message in DL to the UE.

[0160] From E2E system perspective to setup a data path for the UE, a radio bearer context in Radio Network Layer (RNL) needs to be linked to an IP tunnel in Transport Network Layer (TNL). To establish radio bearer context in RAN, the CU-CP needs to communicate with DU to know available radio resources and with CU-UP (in case the CU is further split) to link the radio resources with PDU session resources. This implies association of IP tunnel address for a UE associated radio bearer (as indicated by step 14 and 15 in Fig. 1).

[0161] Note that the logical nodes in the disaggregated architecture can be physically separated over long distances (e.g., the distance between the CU and the DU can be of the order of hundreds of kilometres). Therefore, any information exchange between the two is subject to relatively long propagation delay. Latency has been one of the key KPIs that is envisioned to be even more strict for 6G technology than 5G.

[0162] The existing 5G CU and DU coordination is neither optimal nor useful for 6G RAN, as this is actually maximizing or at least increasing latency as all requests need to be always performed in both CU and in DU to finally setup a connection. As re-design for 6G RAN is foreseen, the redundant messages should be identified and then possibly excluded from the overall connection setup framework.

[0163] A smart solution to the information exchange problem is that the DU capabilities are provided to the 6G CU-CP in advance. In this case the messages that setup the association (14. and 15. of Fig. 1) introduce additional hops in the overall procedure and become redundant. There is no need to negotiate bearer context setup, in case CU owns the information about capabilities of the DU. Therefore, latency cannot be reduced by a more efficient information exchange (than in 5G) alone. The protocol must be redesigned to complement new smart solutions. Embodiments therefore, address this change in the overall bearer setup / modification procedure.

[0164] Embodiments propose an efficient bearer context setup / modification procedure by reducing the effort (signalling) in allocating DU resources and in some embodiments required TNL addresses when the procedure is triggered by, e.g., a UE service request, or for some other reason. Embodiments may be applied to two likely variants of a RAN split architecture in 6G. Particularly, embodiments propose the allocation of IP tunnels for radio bearers from transport network layer TNL to the radio network layer RNL in such a way that the involved procedure, i.e. , the radio bearer association to the endpoint (i.e. , a TNL address), is done by a single network entity (i.e., the CU-CP or the “RAN CP”) without needing to request information from the DU first, as done previously in 5G each time this procedure is required (e.g., in UE service requests). The CU-CP / RAN-CP then configures the involved and assisting network entities (i.e., the DU and possibly the RAN-UP / CU-UP), and the UE with the immediate outcome of the association (i.e., identifiers of the allocated bearers and tunnel addresses).

[0165] As a result, upon receiving a trigger in RAN (e.g., user service request, Core Network signalling), the CU-CP / RAN-CP selects the DU for handling radio resources of the user, associates the DU with the endpoint of a radio resource bearer (i.e., a TNL address) without first acquiring it from the DU, associates the radio bearer identifiers with the session addresses (i.e., a TNL address), and communicates the TNL address to the RAN-UP / CU-UP in the case that the CU is split in the CP and the UP nodes (split variant two).

[0166] The advantage of embodiments is that the entire procedure which is triggered by every UE service request or modification is accelerated (in contrast to 5G). Keeping in mind the stringent 6G latency requirements, this shall go a long way in reducing the overall CP latency which is a drawback of the existing 5G CP.

[0167] The concept assumes a RAN split architecture which can have two variants. For 6G, the split architecture in its simplest form assumes the split of a RAN node in a CU and a DU, whereby the CU, in particular, hosts the C-Plane functionality (RAN-CP / CU-CP) and it is able to communicate directly with the UE (which requires the CU to host the RRC protocol).

[0168] In this regard, a base station may have multiple entities such as a control plane apparatus and a distributed apparatus. The distributed apparatus provides radio coverage to user equipment via at least one cell and handles a physical layer of a radio protocol stack of the base station, while the control plane apparatus handles a radio resource control layer of the radio protocol stack of the base station. The base station is configured so that the distributed apparatus sends information regarding its characteristics or capabilities in an unsolicited message to the control plane apparatus. This allows the control plane apparatus to assign to the distributed apparatus and to the user equipment, a physical layer configuration required for communication between the user equipment and the distributed apparatus in response to a user equipment service request using the capabilities information and information in the service request.

[0169] The following description may provide further details of alternatives, modifications and variances: a gNB comprises e.g. a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC, e.g. according to 3GPP standard specifications.

[0170] A gNB Central Unit (gNB-CU) comprises e.g. a logical node hosting e.g. RRC (radio resource control), SDAP (service data adaptation protocol) and PDCP (packet data convergence protocol) protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected with the gNB-DU.

[0171] A gNB Distributed Unit (gNB-DU) comprises e.g. a logical node hosting e.g. RLC (radio link control), MAC (medium access control) and PHY (physical) layers of the gNB or en- gNB, and its operation is partly controlled by the gNB-CU. One gNB-DU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected with the gNB-CU.

[0172] A gNB-CU-Control Plane (gNB-CU-CP) comprises e.g. a logical node hosting e.g. the RRC and the control plane part of the PDCP protocol of the gNB-CU for an en-gNB or a gNB. The gNB-CU-CP terminates the E1 interface connected with the gNB-CU-UP and the F1-C interface connected with the gNB-DU.

[0173] A gNB-CU-User Plane (gNB-CU-UP) comprises e.g. a logical node hosting e.g. the user plane part of the PDCP protocol of the gNB-CU for an en-gNB, and the user plane part of the PDCP protocol and the SDAP protocol of the gNB-CU for a gNB. The gNB-CU- UP terminates the E1 interface connected with the gNB-CU-CP and the F1-U interface connected with the gNB-DU, e.g. according to 3GPP standard specifications.

[0174] Different functional splits between the central and distributed unit are possible, e.g. called options:

[0175] Option 1 (1 A-like split):

[0176] The function split in this option is similar to the 1A architecture in DC. RRC is in the central unit. PDCP, RLC, MAC, physical layer and RF are in the distributed unit.

[0177] Option 2 (3C-like split):

[0178] The function split in this option is similar to the 3C architecture in DC. RRC and PDCP are in the central unit. RLC, MAC, physical layer and RF are in the distributed unit.

[0179] Option 3 (intra RLC split): Low RLC (partial function of RLC), MAC, physical layer and RF are in the distributed unit. PDCP and high RLC (the other partial function of RLC) are in the central unit.

[0180] Option 4 (RLC-MAC split):

[0181] MAC, physical layer and RF are in the distributed unit. PDCP and RLC are in the central unit.

[0182] Or else, e.g. according to 3GPP TR 38.801 V14.0.0 (2017-03) section 11 incorporated by reference.

[0183] A gNB supports different protocol layers, e.g. Layer 1 (L1) - physical layer.

[0184] The layer 2 (L2) of NR is split into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP), where e.g.:

[0185] The physical layer offers to the MAC sublayer transport channels;

[0186] The MAC sublayer offers to the RLC sublayer logical channels; The RLC sublayer offers to the PDCP sublayer RLC channels; The PDCP sublayer offers to the SDAP sublayer radio bearers; The SDAP sublayer offers to 5GC QoS flows;

[0187] Comp, refers to header compression and Segm. to segmentation;

[0188] Control channels include (BCCH, PCCH).

[0189] A RAN (Radio Access Network) node or network node or central node or distributed node like e.g. a gNB, base station, gNB CU or gNB DU or parts thereof may be implemented using e.g. an apparatus with at least one processor and / or at least one memory (with computer-readable instructions (computer program)) configured to support and / or provision and / or process CU and / or DU related functionality and / or features, and / or at least one protocol (sub-)layer of a RAN (Radio Access Network), e.g. layer 2 and / or layer 3. They may also be implemented using specific means configured to perform respective specific tasks, e.g. layer 3 means to perform layer 3 operations, layer 2 means to perform layer 2 operations, etc. A central node may e.g. implement CU-CP and / or CP-UP functionality.

[0190] The gNB CU and gNB DU parts may e.g. be co-located or physically separated. The gNB DU may even be split further, e.g. into two parts, e.g. one including processing equipment and one including an antenna. A Central Unit (CU) may also be called BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or part thereof. A Distributed Unit (DU) may also be called RRH / RRU / RE / RU, or part thereof.

[0191] A gNB-DU supports one or multiple cells, and could thus serve as e.g. a serving cell for a user equipment (UE).

[0192] A user equipment (UE) may include a wireless or mobile device, an apparatus with a radio interface to interact with a RAN (Radio Access Network), a smartphone, an in- vehicle apparatus, an loT device, a M2M device, or else. Such UE or apparatus may comprise: at least one processor; and at least one memory including computer program code; wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform certain operations, like e.g. RRC connection to the RAN. A UE is e.g. configured to generate a message (e.g. including a cell ID) to be transmitted via radio towards a RAN (e.g. to reach and communicate with a serving cell). A UE may generate and transmit and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0193] A UE is e.g. either in RRC_CONNECTED state or in RRCJNACTIVE state when an RRC connection has been established.

[0194] In RRC_CONNECTED state a UE may: store the AS context; transfer unicast data to / from the UE; monitor control channels associated with the shared data channel to determine if data is scheduled for the data channel; provide channel quality and feedback information; perform neighboring cell measurements and measurement reporting;

[0195] The RRC protocol includes e.g. the following main functions:

[0196] RRC connection control; measurement configuration and reporting; establishment / modification / release of measurement configuration (e.g. intrafrequency, inter-frequency and inter-RAT measurements); setup and release of measurement gaps;

[0197] - measurement reporting. A list of some abbreviations used:

[0198] CP Control Plane

[0199] CU Central Unit

[0200] DL Downlink

[0201] DU Distributed Unit

[0202] E2E End-to-end

[0203] MAC Medium Access Control

[0204] PDCP Protocol Data Convergence Protocol

[0205] PDU Packet Data Unit

[0206] RAN Radio Access Network

[0207] RLC Radio Link Control

[0208] RNL Radio Network Layer

[0209] RRC Radio Resource Control

[0210] TNL Transport Network Layer

[0211] UE User Equipment

[0212] UL Uplink

[0213] UP User Plane

[0214] A person of skill in the art would readily recognize that steps of various above-described methods can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machine-executable or computerexecutable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods. The tern non-transitory as used herein, is a limitation of the medium itself (i.e. , tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

[0215] As used in this application, the term “circuitry” may refer to one or more or all of the following:

[0216] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0217] (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and

[0218] (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0219] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0220] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0221] Although example embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

[0222] Features described in the preceding description may be used in combinations other than the combinations explicitly described.

[0223] Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

[0224] Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

[0225] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and / or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. A control plane apparatus of a base station comprising: at least one processor; and at least one memory storing instructions that when executed by said at least one processor cause said control plane apparatus at least to perform: receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell, and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; storing said configuration characteristics in said at least one memory of said control plane apparatus; in response to receipt of a service request from the user equipment, retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

2. The control plane apparatus of claim 1 , wherein the control plane apparatus is caused to perform said step of receiving configuration characteristics from the distributed apparatus prior to receiving the service request from the user equipment.

3. The control plane apparatus according to claim 1 or 2, wherein said configuration characteristics comprise an indication of radio resources available to said distributed apparatus.

4. The control plane apparatus according to claim 3, wherein said step of assigning said physical layer configuration comprises selecting radio resources for communication between the distributed apparatus and the user equipment from said radio resources indicated as being currently available to said distributed apparatus by said stored configuration characteristics.

5. The control plane apparatus according to claim 3 or 4, said control plane apparatus being further caused to update said at least one memory storing said configuration characteristics based on allocated resources of said distributed apparatus.

6. The control plane apparatus according to any preceding claim, wherein said configuration characteristics are received during a network setup procedure.

7. The control plane apparatus according to claim 6, wherein said network setup procedure, comprises a procedure performed when setting up the network or a procedure performed when configuring an interface or a procedure performed during an interface configuration update.

8. The control plane apparatus according to any preceding claim, said control plane apparatus being caused in response to receipt of a further user equipment service request, to determine whether there is configuration information stored in said at least one memory for a distributed apparatus providing radio coverage to said further user equipment; and where so: to retrieve said information regarding configuration characteristics of said distributed apparatus and to assign at least a physical layer configuration required for communication between said further user equipment and said distributed apparatus in dependence upon said configuration characteristics and said user equipment service request; and where not: to generate a message for transmission to the distributed apparatus requesting configuration information from said distributed apparatus.

9. The control plane apparatus according to any preceding claim, said control plane apparatus being further caused to perform: causing transmission of an indication of said assigned physical layer configuration to said distributed apparatus.

10. The control plane apparatus according to any preceding claim, said control plane apparatus being further caused to perform: causing transmission of an indication of said assigned physical layer configuration to said user equipment.

11. The control plane apparatus according to any preceding claim, wherein said at least one memory is configured to store configuration characteristics of a plurality of distributed apparatuses each providing radio coverage via at least one cell.

12. The control plane apparatus according to any preceding claim, said control plane apparatus being further caused to select a distributed apparatus for providing radio coverage for said user equipment and to retrieve from said data store information regarding configuration characteristics of said selected distributed apparatus for use in said assigning of said physical layer configuration.

13. The control plane apparatus according to any preceding claim, wherein said assigned physical layer configuration includes a transport network layer TNL address.

14. The control plane apparatus according to claim 13, wherein said assigning of said physical layer configuration comprises allocating an IP tunnel for radio bearers from TNL to the radio network layer RNL.

15. The control plane apparatus according to any preceding claim, wherein said control plane apparatus comprises a gNB-Cll node.

16. The control plane apparatus according to claim 15, wherein said control plane apparatus is configured to host the control plane part of the packet data convergence protocol PDCP, the base station comprising a corresponding user plane control apparatus configured to host the user plane part of the PDCP protocol.

17. The control plane apparatus according to claim 16, when dependent upon claim 13 or 14, said control plane apparatus being further caused to transmit said TNL address to said corresponding user plane control apparatus.

18. A method performed at a control plane apparatus of a base station, said method comprising: receiving, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus providing radio coverage to the user equipment via at least one cell, wherein said distributed apparatus handles at least a physical layer of a radio protocol stack of the base stationand said control plane apparatus handles at least a part of a radio resource control layer of the radio protocol stack of the base station; storing said configuration characteristics in said at least one memory of said control plane apparatus; receiving a service request from a user equipment; retrieving from said at least one memory information regarding configuration characteristics of said distributed apparatus; and assigning, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

19. A computer program comprising computer readable instructions which when executed by a processor on a control plane apparatus of a base station are operable to control said control plane apparatus to: receive, from a distributed apparatus of the base station configuration characteristics of said distributed apparatus, said configuration characteristics providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus, said distributed apparatus being for providing radio coverage to the user equipment via at least one cell and for handling at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; store said configuration characteristics; in response to receipt of a service request from the user equipment, retrieve information regarding configuration characteristics of said distributed apparatus; and assign, to the distributed apparatus and to the user equipment, at least a physical layer configuration required for communication between said user equipment and said distributed apparatus in dependence upon said retrieved information regarding the configuration characteristics and said service request.

20. A distributed apparatus of a base station, said distributed apparatus comprising: at least one processor; and at least one memory storing instructions that when executed by the at least one processor cause the distributed apparatus at least to perform: generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus ofthe base station, said distributed apparatus being configured to provide radio coverage to the user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack of the base station and said control plane apparatus being configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station; causing transmission of said message to said control plane apparatus.

21. The distributed apparatus according to claim 20, wherein said message generated by said distributed apparatus comprises configuration characteristics of said distributed apparatus, said configuration characteristics comprising information required for physical layer configuration for said communication between said distributed apparatus and said user equipment.

22. The distributed apparatus according to claim 21 , wherein said configuration characteristics comprise information indicative of radio resources available to said distributed apparatus.

23. The distributed apparatus according to claim 21 or 22, wherein said configuration characteristics comprise an indication of at least one of: physical uplink shared channel PLISCH resources, random access channel RACH configurations, or a range of cell network temporary identifiers C-RNTIs, and additionally at least some further assistance information; wherein said further assistance information comprises: capability indicators indicating support for particular functions, explicit configuration of radio resources, frequency capabilities, frequency band(s), Bandwidth Part, Bandwidth capabilities, channel capabilities, cell information, cell identifiers, beams configuration, synchronisation signal block SSB, channel state information reference signal CSI-RS, scheduling capabilities such as maximum number of simultaneously supported UEs, timing restrictions, measurement gaps information, cell Group Config, Reference signal config, time domain table, cell-specific operations, HW information such as antennas configurations, carrier aggregation support, native carrier aggregation, (de)modulation mode, maximum capabilities.

24. The distributed apparatus according to any one of claims 20 to 22, wherein said distributed apparatus is caused to transmit said configuration characteristics during a network setup procedure.

25. The distributed apparatus according to claim 24, wherein said network setup procedure comprises a procedure performed when setting up the network or a procedure performed when configuring an interface or a procedure performed during an interface configuration update.

26. The distributed apparatus according to any one of claims 20 to 25, wherein said transmission of said configuration characteristics is an unsolicited transmission.

27. The distributed apparatus according to any one of claims 20 to 26, said apparatus being further caused to: receive a network configuration command from said control plane apparatus, the command comprising at least a physical layer configuration required for communication between said user equipment and said distributed apparatus; configure resources based on said network configuration command; and communicate with said user equipment using said configured resources.

28. A method performed at a distributed apparatus of a base station, the distributed apparatus providing radio coverage to the user equipment via at least one cell and handling at least a physical layer of a radio protocol stack of the base station, wherein a control plane apparatus of the base station is configured to handle at least a part of a radio resource control layer of the radio protocol stack of the base station, said method comprising: generating a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by said control plane apparatus; and transmitting said message to said control plane apparatus.

29. A method according to claim 28, said method further comprising: receiving a configuration command from said control plane apparatus; configuring resources indicated by said configuration command; and transmitting a message to said user equipment using said configured resources.

30. A computer program comprising computer readable instructions which when executed by a processor on a distributed apparatus of a base station, the distributed apparatus being configured to provide radio coverage to a user equipment via at least one cell and to handle at least a physical layer of a radio protocol stack, and wherein a control plane apparatus of the base station is configured to handle at least a part of aradio resource control layer of the radio protocol stack, are operable to control the distributed apparatus at least to: generate a message providing an indication that said distributed apparatus can be configured for communication with a user equipment by a control plane apparatus; and transmit said message to said control plane apparatus..31 A user plane apparatus of a base station, said user plane apparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station; comprising: at least one processor; and at least one memory storing instructions that when executed by said at least one processor cause said user plane apparatus at least to perform: receiving a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus being configured to handle at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and based on said bearer context request and the TNL address, setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

32. A user plane apparatus according to claim 31 , said user plane apparatus being further caused to perform a transmission of an indication that said bearer context setup is performed as a bearer context setup response.

33. A method performed at a user plane apparatus of a base station, said user plane apparatus handling at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, said method comprising: receiving a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus handling at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and based on said bearer context request and the TNL address, setting up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

34. A computer program comprising computer readable instructions which when executed by a processor on a user plane apparatus of a base station said user planeapparatus being configured to handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, causes said user plane apparatus at least to: handle at least a user plane part of a radio resource control layer of the radio protocol stack of the base station, are operable to control said user plane apparatus to: receive a bearer context setup request from a control plane apparatus of the base station, said control plane apparatus being configured to handle at least a control plane part of a radio resource control layer of the radio protocol stack of the base station, said bearer context set up request comprising a transport network layer TNL address; and based on said bearer context request and the TNL address, set up a bearer for a user equipment to communicate with a distributed apparatus of the base station.

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