Patent Description:
In the 3rd Generation Partnership Project (3GPP), which is a standardization project of a cellular communication system, a study is underway to introduce a new relay node referred to as an Integrated Access and Backhaul (IAB) node. One or more relay nodes are involved in communication between a base station and user equipment, and perform relay for the communication.

In the 3GPP, a study is underway to introduce a private network called a Non-Public Network (NPN). However, a method for communication control in a case that an NPN and an IAB node co-exist is not established.

"<NPL>, discloses a Radio Resource Control protocol for the radio interface between UE and NG-RAN.

"<NPL>, discloses a change to TS <NUM> to introduce IAB.

The present invention provides a communication control method according to claim <NUM>, a chipset according to claim <NUM>, a relay node according to claim <NUM>, a base station according to claim <NUM>, a computer program according to claim <NUM>, and a system according to claim <NUM>. Further embodiments of the present invention are disclosed in the dependent claims.

A cellular communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference signs.

First, a configuration of the cellular communication system according to an embodiment will be described. <FIG> is a diagram illustrating a configuration of a cellular communication system <NUM> according to an embodiment.

The cellular communication system <NUM> is a fifth generation (<NUM>) cellular communication system based on the 3GPP standard. Specifically, a radio access scheme in the cellular communication system <NUM> is New Radio (NR) being a radio access scheme of the <NUM>. Note that Long Term Evolution (LTE) may be at least partially applied to the cellular communication system <NUM>.

As illustrated in <FIG>, the cellular communication system <NUM> includes a <NUM> core network (5GC) <NUM>, user equipment (UE) <NUM>, a base station (referred to as a gNB) <NUM>, and an IAB node <NUM>. The IAB node <NUM> is an example of a relay node. An embodiment mainly describes an example in which the base station is an NR base station. However, the base station may be an LTE base station (specifically, an eNB).

The 5GC <NUM> includes an Access and Mobility Management Function (AMF) <NUM> and a User Plane Function (UPF) <NUM>. The AMF <NUM> is an apparatus that performs various types of mobility control and the like for the UE <NUM>. By communicating with the UE <NUM> by using Non-Access Stratum (NAS) signaling, the AMF <NUM> manages information of an area in which the UE <NUM> exists. The UPF <NUM> is an apparatus that performs transfer control of user data and the like.

Each gNB <NUM> is a fixed wireless communication node that manages one or more cells. The cell is used as a term denoting a minimum unit of a wireless communication area. The cell may be used as a term denoting a function or a resource for performing wireless communication with the UE <NUM>. One cell belongs to one carrier frequency.

Each gNB <NUM> is connected to the 5GC <NUM> via an interface referred to as an NG interface. <FIG> illustrates two gNBs, a gNB <NUM>-<NUM> and a gNB <NUM>-<NUM> that are connected to the 5GC <NUM>.

Each gNB <NUM> is connected to another gNB <NUM> in an adjacency relationship via an inter-base station interface referred to as an Xn interface. <FIG> illustrates an example in which the gNB <NUM>-<NUM> is connected to the gNB <NUM>-<NUM>.

Each gNB <NUM> may be divided into a central unit (CU) and a distributed unit (DU). The CU and the DU are connected to each other via an interface referred to as an F1 interface. The F1 protocol is a communication protocol between the CU and the DU, and includes an F1-C protocol corresponding to a protocol for a control plane and an F1-U protocol corresponding to a protocol for a user plane.

The cellular communication system <NUM> supports an IAB that uses NR for the backhaul to enable wireless relay of NR access. The donor gNB <NUM>-<NUM> is a gNB <NUM> corresponding to a terminal node of the NR backhaul on the network side and including additional functions that support the IAB. The backhaul is capable of multi-hop via a plurality of hops (i.e., a plurality of IAB nodes <NUM>).

Each IAB node <NUM> includes a DU corresponding to a first function unit and a Mobile Terminal (MT) corresponding to a second function unit.

The MT is connected to the DU of an upper node (upper IAB node or a donor gNB <NUM>-<NUM>). The MT is connected to the CU of the donor gNB <NUM>-<NUM> by using RRC, and establishes, with the donor gNB <NUM>-<NUM>, a signaling radio bearer (SRB) that carries an RRC message and an NAS message. An adjacent node on an NR Uu wireless interface of the MT (i.e., an upper node) may be referred to as a "parent node". A radio link between the MT of the IAB node <NUM> and the upper node is referred to as a backhaul link (BH link).

The DU manages cells similarly to the gNB <NUM>. The DU terminates the NR Uu wireless interface to the UE <NUM> and a lower IAB node. The DU supports the F1 protocol for the CU of the donor gNB <NUM>-<NUM>. An adjacent node on an NR access interface of the DU (i.e., lower node) may be referred to as a "child node".

All IAB nodes <NUM> connected to the donor gNB <NUM>-<NUM> via one or more hops form a Directed Acyclic Graph (DAG) topology rooted in the donor gNB <NUM>-<NUM>. The DAG topology may be referred to as an IAB topology. In the DAG topology, a direction of the parent node may be referred to as "upstream" or "upper", and a direction of the child node may be referred to as "downstream" or "lower".

An example is illustrated in <FIG> in which an IAB node <NUM>-<NUM> is wirelessly connected to the donor gNB <NUM>-<NUM>, an IAB node <NUM>-<NUM> is wirelessly connected to the IAB node <NUM>-<NUM>, and the F1 protocol is transmitted via two backhaul hops.

The UE <NUM> is a mobile wireless communication apparatus that performs wireless communication with cells. The UE <NUM> may be any type of apparatus as long as the UE <NUM> is an apparatus that performs wireless communication with the gNB <NUM> or the IAB node <NUM>. For example, the UE <NUM> is a mobile phone terminal, a tablet terminal, a notebook PC, a sensor or an apparatus provided in the sensor, and/or a vehicle or an apparatus provided in the vehicle. The UE <NUM> is wirelessly connected to an upper node (IAB node <NUM> or gNB <NUM>) via an access link.

<FIG> illustrates an example in which the UE <NUM> is wirelessly connected to the IAB node <NUM>-<NUM>. The UE <NUM> indirectly communicates with the donor gNB <NUM>-<NUM> via the IAB node <NUM>-<NUM> and the IAB node <NUM>-<NUM>. Specifically, the IAB node <NUM>-<NUM> and the IAB node <NUM>-<NUM> relay uplink data from the UE <NUM> to the donor gNB <NUM>-<NUM> and relay downlink data from the gNB <NUM>-<NUM> to the UE <NUM>.

A configuration of the gNB <NUM>, corresponding to a base station according to an embodiment, will be described. <FIG> is a diagram illustrating a configuration of the gNB <NUM>. As illustrated in <FIG>, the gNB <NUM> includes a wireless communicator <NUM>, a network communicator <NUM>, and a controller <NUM>.

The wireless communicator <NUM> performs wireless communication with the UE <NUM> and performs wireless communication with the IAB node <NUM>. The wireless communicator <NUM> includes a receiver <NUM> and a transmitter <NUM>. The receiver <NUM> performs various types of receptions under control of the controller <NUM>. The receiver <NUM> includes an antenna, and converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the controller <NUM>. The transmitter <NUM> performs various types of transmissions under control of the controller <NUM>. The transmitter <NUM> includes an antenna, and converts a baseband signal (transmission signal) output by the controller <NUM> into a radio signal and transmits the radio signal from the antenna.

The network communicator <NUM> performs wired communication (or wireless communication) with the 5GC <NUM> and performs wired communication (or wireless communication) with another neighboring gNB <NUM>. The network communicator <NUM> includes a receiver <NUM> and a transmitter <NUM>. The receiver <NUM> performs various types of receptions under control of the controller <NUM>. The receiver <NUM> receives a signal from the outside and outputs the received signal to the controller <NUM>. The transmitter <NUM> performs various types of transmissions under control of the controller <NUM>. The transmitter <NUM> transmits a transmission signal output by the controller <NUM> to the outside.

The controller <NUM> performs various types of control for the gNB <NUM>. The controller <NUM> includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used for processing by the processor. The processor may include a baseband processor and a Central Processing Unit (CPU). The baseband processor performs modulation and demodulation, and coding and decoding of a baseband signal, and the like. The CPU executes the programs stored in the memory to perform various types of processes. The processor executes processing of layers described below.

A configuration of the IAB node <NUM>, corresponding to a relay node according to an embodiment will be described. <FIG> is a diagram illustrating a configuration of the IAB node <NUM>. As illustrated in <FIG>, the IAB node <NUM> includes a wireless communicator <NUM> and a controller <NUM>. The IAB node <NUM> may include a plurality of wireless communicators <NUM>.

The wireless communicator <NUM> performs wireless communication (BH link) with the gNB <NUM> and performs wireless communication (access link) with the UE <NUM>. The wireless communicator <NUM> for the BH link communication and the wireless communicator <NUM> for the access link communication may be provided separately.

The wireless communicator <NUM> includes a receiver <NUM> and a transmitter <NUM>. The receiver <NUM> performs various types of receptions under control of the controller <NUM>. The receiver <NUM> includes an antenna, and converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the controller <NUM>. The transmitter <NUM> performs various types of transmissions under control of the controller <NUM>. The transmitter <NUM> includes an antenna, and converts a baseband signal (transmission signal) output by the controller <NUM> into a radio signal and transmits the radio signal from the antenna.

The controller <NUM> performs various types of control for the IAB node <NUM>. The controller <NUM> includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, and coding and decoding of a baseband signal, and the like. The CPU executes the programs stored in the memory to perform various types of processes. The processor executes processing of the layers described below.

A configuration of the UE <NUM>, corresponding to user equipment according to an embodiment, will be described. <FIG> is a diagram illustrating a configuration of the UE <NUM>. As illustrated in <FIG>, the UE <NUM> includes a wireless communicator <NUM> and a controller <NUM>.

The wireless communicator <NUM> performs wireless communication in the access link, specifically, wireless communication with the gNB <NUM> and wireless communication with the IAB node <NUM>. The wireless communicator <NUM> may perform wireless communication in the sidelink, in other words, wireless communication with another UE <NUM>. The wireless communicator <NUM> includes a receiver <NUM> and a transmitter <NUM>. The receiver <NUM> performs various types of receptions under control of the controller <NUM>. The receiver <NUM> includes an antenna, and converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the controller <NUM>. The transmitter <NUM> performs various types of transmissions under control of the controller <NUM>. The transmitter <NUM> includes an antenna, and converts a baseband signal (transmission signal) output by the controller <NUM> into a radio signal and transmits the radio signal from the antenna.

The controller <NUM> performs various types of controls for the UE <NUM>. The controller <NUM> includes at least one memory and at least one processor electrically connected to the memory. The memory stores programs to be executed by the processor and information to be used for processing by the processor. The processor may include a baseband processor and a CPU. The baseband processor performs modulation and demodulation, and coding and decoding of a baseband signal, and the like. The CPU executes the programs stored in the memory to perform various types of processes. The processor executes processing of the layers described below.

An example of a protocol stack in the cellular communication system <NUM> according to an embodiment will be described. <FIG> and <FIG> are diagrams illustrating examples of a protocol stack in the cellular communication system <NUM> according to an embodiment.

In <FIG> and <FIG>, illustration of a Medium Access Control (MAC) layer and a Physical layer (PHY) layer being lower layers of a Radio Link Control (RLC) layer are omitted. Note that the PHY layer is a layer that performs coding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Between the PHY layers, data and control information are transmitted via a physical channel. The MAC layer performs preferential control of data, retransmission processing through a hybrid ARQ (HARQ) and other processing. Between the MAC layers, data and control information are transmitted via a transport channel. The MAC layer of the DU includes a scheduler. By performing scheduling processing, the scheduler determines transport formats (transport block sizes, modulation and coding schemes (MCSs)) in the uplink and the downlink and resource blocks (allocation radio resources) to be allocated to the UE <NUM>.

As illustrated in <FIG>, the donor gNB <NUM>-<NUM> is divided into the CU and the DU, and includes an F1-C interface (Intra-donor F1-C) between the CU and the DU. A Packet Data Convergence Protocol (PDCP) layer of the CU and a PDCP layer of the UE <NUM> communicate with each other via the IAB nodes <NUM>-<NUM> and <NUM>-<NUM>. The PDCP layer is a layer that performs header compression and decompression, and encryption and decryption. A Radio Resource Control (RRC) layer of the CU and an RRC layer of the UE <NUM> communicate with each other via the IAB nodes <NUM>-<NUM> and <NUM>-<NUM>. The RRC layer transmits RRC signaling for various configurations. The RRC layer controls a logical channel, a transport channel, and a physical channel according to establishment, reestablishment, and release of a radio bearer. When there is RRC connection between the RRC layers, the UE <NUM> is in an RRC connected state. When there is no RRC connection between the RRC layers, the UE <NUM> is in an RRC idle state.

In the DU and the MT, a Backhaul Adaptation Protocol (BAP) layer is provided as an upper layer of the RLC layer. The BAP layer is a layer that performs routing processing and bearer mapping and demapping processing. Note that the UE <NUM> and the DU of the IAB node <NUM>-<NUM> do not include a BAP layer.

As illustrated in <FIG>, an F1 Application Protocol (F1-AP) layer of the CU and an F1-AP layer of the DU of the IAB node <NUM>-<NUM> communicate with each other via the IAB node <NUM>-<NUM>. The RRC layer of the CU and the RRC layer of the MT of the IAB node <NUM>-<NUM> communicate with each other via the IAB node <NUM>-<NUM>. The PDCP layer of the CU and the PDCP layer of the MT of the IAB node <NUM>-<NUM> communicate with each other via the IAB node <NUM>-<NUM>.

Note that, although illustration is omitted in <FIG>, the F1-AP layer of the CU and the F1-AP layer of the DU of the IAB node <NUM>-<NUM> communicate with each other. The RRC layer of the CU and the RRC layer of the MT of the IAB node <NUM>-<NUM> communicate with each other. The PDCP layer of the CU and the PDCP layer of the MT of the IAB node <NUM>-<NUM> communicate with each other.

<FIG> is a diagram illustrating an example of a system information block type <NUM> (hereinafter, referred to as an "SIB1") broadcast by the donor gNB <NUM>-<NUM>. The donor gNB <NUM>-<NUM> broadcasts (specifically, transmits on the broadcast channel) the SIB1 for each cell managed by the donor gNB <NUM>-<NUM> itself. In other words, the SIB1 is cell-specific information.

As illustrated in <FIG>, the SIB1 broadcast in the cell includes cell access related information (CellAccessRelatedInfo) related to access to the cell.

The cell access related information (CellAccessRelatedInfo) includes a Public Land Mobile Networks (PLMN) identifier information list (PLMN-Identity InfoList). The PLMN identifier information list includes one or more PLMN identifier information elements (PLMNIdentityInfo). The PLMN identifier information elements include a PLMN identifier list (PLMNIdentityList) containing one or more PLMN identifiers (PLMNIdentity).

The PLMN identifier information list includes IAB support information (iab-Support) associated with the PLMN identifier. The IAB support information is an example of relay node support information. The IAB support information (= true) is information indicating that the cell (the PLMN to which the cell belongs) supports the IAB node <NUM>. Supporting the IAB node <NUM> means that the cell has capability to handle the IAB node <NUM> and is an access candidate for the IAB node <NUM>.

Upon receiving the SIB1 in the cell, if the received SIB1 includes the IAB support information (= true), the IAB node <NUM> regards the cell (the PLMN belonging to the cell) as an access candidate. On the other hand, if the received SIB1 does not include the IAB support information (= true), the IAB node <NUM> determines that access to the cell (the PLMN belonging to the cell) is prohibited, and does not regard the cell as an access candidate.

The non-public cellular network (Non-Public Network (NPN)) according to an embodiment will be described. The NPN is a small-scale cellular network that can be used by a specific subscriber. The NPN is, for example, used for the purpose of private wireless communication in a factory. The NPN may be referred to as a private network.

A public cellular network (Public Land Mobile Network (PLMN)), which is a general cellular network, is operated by a telecommunications carrier. For example, a telecommunications carrier operating the PLMN is licensed on a national basis.

On the other hand, the NPN can be flexibly constructed and used by various entities depending on local needs or industrial field-specific needs. The NPN with the <NUM> cell communication system may be referred to as local <NUM>. For example, general companies or organization/individuals can receive frequency assignments to operate the NPN by themselves. A license for the NPN may be issued to only a local area, such as in a general company facility.

The NPN includes two types, specifically a stand-alone NPN and a non-stand-alone NPN. The stand-alone NPN is referred to as the Standalone NPN (SNPN), and the non-stand-alone NPN is referred to as a Public Network Integrated NPN (PNI-NPN). The SNPN and the PNI-NPN are hereinafter simply referred to as the NPN unless otherwise distinguished.

<FIG> is a diagram illustrating the SNPN and the PNI-NPN according to an embodiment.

As illustrated in <FIG>, the SNPN is independent of the PLMN and does not depend on a network function of the PLMN. On the other hand, the PNI-NPN is configured as part of the PLMN and is capable of network cooperation with the PLMN.

Note that each of the PLMN and the NPN may have an NG-RAN <NUM> and a 5GC <NUM>. It is assumed that one or more frequencies (frequency bands, carrier frequencies) are allocated to one NPN. One frequency may be allocated to a plurality of geographically separated NPNs. By separating the geographical areas of the NPNs using one frequency, the same frequency can be shared by the plurality of NPNs.

In a case of the SNPN, a network identifier (NID) for identifying the NPN is allocated to the NPN. An NPN cell (gNB <NUM>) broadcasts the NID of the NPN to which the NPN cell belongs (or the NPN for which the NPN cell provides service, or the NPN for which the NPN cell gives permission to access). Specifically, the NPN cell (gNB <NUM>) belonging to the SNPN broadcasts an SNPN identifier as the NPN identifier by the SIB1. The SNPN identifier is configured by a combination of the PLMN identifier and the NID.

In a case of the PNI-NPN, a Closed Access Group (CAG) identifier as an identifier for identifying the NPN is allocated to the NPN. The NPN cell (gNB <NUM>) broadcasts the CAG identifier of the NPN to which the NPN cell belongs (or the NPN for which the NPN cell provides service, or the NPN for which the NPN cell gives permission to access). Note that the CAG identifier is also an identifier of a group including some specific users that can access the NPN out of subscriber users of the PLMN. Specifically, the NPN cell (gNB <NUM>) belonging to the PNI-NPN broadcasts a PNI-NPN identifier as the NPN identifier by the SIB1. The PNI-NPN identifier is configured by a combination of the PLMN identifier and the CAG identifier.

<FIG> is a diagram illustrating an example of the SIB1 broadcast in the NPN cell. The gNB <NUM> broadcasts (specifically, transmits, on the broadcast channel) the SIB1 for each cell managed by the gNB <NUM> itself.

As illustrated in <FIG>, the SIB1 broadcast in the NPN cell includes cell access related information (CellAccessRelatedInfo) related to access to the cell.

The cell access related information (CellAccessRelatedInfo) includes a PLMN identifier information list (PLMN-IdentityInfoList) and an NPN identifier information list (NPN-IdentityInfoList).

The NPN identifier information list includes one or more NPN identifier information elements (NPN-IdentityInfo). The NPN identifier information elements include an NPN identifier list (Npn-IdentityList) containing one or more NPN identifiers (NPNIdentity).

Upon receiving the SIB1 in the cell, if the received SIB1 includes the NPN identifier information list and the NPN identifier information list includes the NPN identifier of the NPN in which the UE <NUM> has an access right (i.e., the NPN selected by the UE <NUM>), the UE <NUM> regards the cell as an access candidate. If not the above case, the UE <NUM> determines that access to the cell is prohibited, and does not regard as an access candidate.

A communication control method according to an embodiment will be described. In an embodiment, assume a scenario where the IAB node <NUM> accesses the NPN cell under co-existence of the NPN and IAB nodes.

A configuration of the SIB1 as illustrated in <FIG> does not support the IAB node <NUM>. Thus, on receiving the SIB1 like that illustrated in <FIG> in the cell, the IAB node <NUM> determines that the access to the cell is prohibited because the IAB support information is not included in the SIB1. As a result, the IAB node <NUM> cannot access the NPN cell.

The communication control method for enabling the IAB node <NUM> to appropriately access the NPN cell is described below. <FIG> is a flow chart illustrating a communication control method according to an embodiment. The communication control method is used in the cellular communication system <NUM>. The cellular communication system <NUM> includes the IAB node <NUM> for relaying communication between the gNB <NUM> and the UE <NUM>.

As illustrated in <FIG>, the communication control method according to an embodiment includes step S1 in which the gNB <NUM> managing the cell belonging to the NPN broadcasts the SIB1 including the NPN identifier for identifying the NPN, step S2 in which the IAB node <NUM> receives the SIB1 from the gNB <NUM>, and step S3 in which the IAB node <NUM> determines, based on the SIB1, whether access to the cell from the IAB node <NUM> (hereinafter, referred to as "IAB access") is permitted. Step S3 includes a step of determining whether the IAB access is permitted, depending on whether the SIB1 further includes the IAB support information indicating that the cell supports the IAB node <NUM>.

An operation pattern <NUM> according to an embodiment will be described. In the operation pattern <NUM>, the IAB support information is included in the NPN identifier information list.

In other words, in the operation pattern <NUM>, the SIB1 includes the NPN identifier information list. The NPN identifier information list includes one or more NPN identifiers each indicating the corresponding NPN among one or more NPNs to which the cell belongs, and the IAB support information associated with the one or more NPN identifiers included in the NPN identifier information list. Step S3 includes a step of determining whether the IAB access is permitted for the NPN indicated by the NPN identifier, based on the IAB support information included in the NPN identifier information list. This allows the IAB node <NUM> to appropriately determine whether the IAB access is permitted for each NPN.

<FIG> is a diagram illustrating an example of the NPN identifier information list in the SIB1 in the operation pattern <NUM>.

As illustrated in <FIG>, the NPN identifier information list (NPN-Identity InfoList) in the SIB1 in the operation pattern <NUM> includes one or more NPN identifier information elements (NPN-IdentityInfo). The NPN identifier information elements include an NPN identifier list (Npn-IdentityList) containing one or more NPN identifiers (NPNIdentity).

In the operation pattern <NUM>, the NPN identifier information list includes the IAB support information (iab-Support) associated with the NPN identifier. The IAB support information (= true) is information indicating that the cell (the NPN to which the cell belongs) supports the IAB node <NUM>.

To make the IAB access to the selected NPN, first, the IAB node <NUM> determines whether the NPN identifier of the selected NPN is included in the NPN identifier information list included in the SIB1 broadcast in the cell. If the NPN identifier of the selected NPN is not included in the NPN identifier information list, the IAB node <NUM> excludes the cell from the access candidate.

Second, if the NPN identifier of the selected NPN is included in the NPN identifier information list, the IAB node <NUM> determines whether the IAB support information (= true) is associated with the NPN identifier.

Third, if the IAB support information (= true) is associated with the selected NPN identifier, the IAB node <NUM> determines that the IAB access to the cell is permitted, and regards the cell as an access candidate. On the other hand, if the IAB support information (= true) is not associated with the selected NPN identifier, the IAB node <NUM> determines that the IAB access to the cell (the NPN to which the cell belongs) is prohibited, and does not regard the cell as an access candidate.

An operation pattern <NUM> according to an embodiment will be described. In the operation pattern <NUM>, the IAB support information is included in the PLMN identifier information list.

In an operation pattern 2a, the SIB1 includes the PLMN identifier information list. The PLMN identifier information list includes one or more PLMN identifiers each indicating the corresponding Public Land Mobile Network (PLMN) among one or more PLMNs to which the cell belongs and the IAB support information associated with the one or more PLMN identifiers included in the PLMN identifier information list. Step S3 includes a step of determining whether the IAB access is permitted for the NPN indicated by the NPN identifier, based on the IAB support information included in the PLMN identifier information list.

<FIG> is a diagram illustrating an example of cell access related information (CellAccessRelatedInfo) in the SIB1 in the operation pattern 2a.

As illustrated in <FIG>, the cell access related information (CellAccessRelatedInfo) in the operation pattern 2a is configured by a combination of the PLMN identifier information list (PLMN-IdentityInfoList) illustrated in <FIG> and the NPN identifier information list (NPN-Identity InfoList) illustrated in <FIG>.

In the operation pattern 2a, the IAB support information (iab-Support) is assumed to be cell-specific information for the NPN. Specifically, for PLMN, the IAB support information is PLMN-specific information (i.e., information notified for each PLMN), but for NPN, the IAB support information is regarded as cell-specific information. The IAB node <NUM> to make the IAB access to the NPN ignores the PLMN identifier for the IAB support information.

Second, if the NPN identifier of the selected NPN is included in the NPN identifier information list, the IAB node <NUM> determines whether the IAB support information (= true) is included in the PLMN identifier information list. Here, the IAB node <NUM> ignores the PLMN identifier in the PLMN identifier information list. However, the IAB node <NUM> may check only the first entry of the PLMN identifier list (plmn-IdentityList) in the PLMN identifier information list.

Third, if the IAB support information (= true) is included in the PLMN identifier information list, the IAB node <NUM> determines that the IAB access to the cell is permitted, and regards the cell as an access candidate. On the other hand, if the IAB support information (= true) is not included in the PLMN identifier information list, the IAB node <NUM> determines that the IAB access to the cell (the NPN to which the cell belongs) is prohibited, and does not regard the cell as an access candidate.

In the operation pattern 2a (and an operation pattern 2b described below), the IAB support information may include information indicating whether the IAB support information is applicable to the NPN. In such a case, step S3 includes a step of determining whether the IAB access is permitted for the NPN indicated by the NPN identifier, depending on whether the IAB support information included in the PLMN identifier information list is applicable to the NPN.

<FIG> is a diagram illustrating a variation of IAB support information in the operation patterns 2a (and the operation pattern 2b described below).

As illustrated in <FIG>, the IAB support information includes any one of information (plmn-only-applicable) indicating that the IAB support information is applicable only to the PLMN, information (npn-only-applicable) indicating that the IAB support information is applicable only to the NPN, or information (true) indicating that the IAB support information is applicable to both the PLMN and the NPN.

If the NPN identifier of the selected NPN is included in the NPN identifier information list, the IAB node <NUM> determines whether the IAB support information applicable to the NPN (npn-only-applicable or true) is included in the PLMN identifier information list. Then, if the IAB support information applicable to the NPN (npn-only-applicable or true) is included in the PLMN identifier information list, the IAB node <NUM> determines that the IAB access to the cell is permitted, and regards the cell as an access candidate. On the other hand, if the IAB support information applicable to the NPN (npn-only-applicable or true) is not included in the PLMN identifier information list, in other words, if the IAB support information is not present or the IAB support information is "plmn-only-applicable", the IAB node <NUM> determines that the IAB access to the cell (the NPN to which the cell belongs) is prohibited, and does not regard the cell as an access candidate.

A configuration of cell access related information (CellAccessRelatedInfo) in the operation pattern 2b is similar to that in the operation pattern 2a. However, the IAB node <NUM> ignores the PLMN identifier in the PLMN identifier information list in the operation pattern 2a, but in the operation pattern 2b, the IAB node <NUM> considers the PLMN identifier in the PLMN identifier information list.

As illustrated in <FIG>, the NPN identifier includes a first part containing the PLMN identifier and a second part containing the CAG identifier or the network identifier (NID). Step S3 includes a step of determining whether the IAB access is permitted for the NPN indicated by the NPN identifier, based on the IAB support information associated with the PLMN identifier matching the first part of the NPN identifier in the PLMN identifier information list. Specifically, if the PLMN identifier information list includes a PLMN identifier matching a PLMN identifier part of the NPN identifier of the NPN ("PLMN identifier + CAG Identifier" or "PLMN identifier + NID"), the IAB node <NUM> interprets the IAB support information corresponding to the PLMN identifier in the PLMN identifier information list, as the IAB support information for the NPN.

Second, if the NPN identifier of the selected NPN is included in the NPN identifier information list, the IAB node <NUM> identifies the PLMN identifier in the PLMN identifier information list matching with the PLMN identifier included in the NPN identifier of the selected NPN.

Third, the IAB node <NUM> determines whether the IAB support information (= true) is associated with the identified PLMN identifier in the PLMN identifier information list. Note that, if the configuration of the IAB support information as illustrated in <FIG> is employed, the IAB node <NUM> may determine whether the IAB support information is applicable to the NPN, as described above.

Fourth, if the IAB support information (= true) is associated with the identified PLMN identifier in the PLMN identifier information list, the IAB node <NUM> determines that the IAB access to the cell is permitted, and regards the cell as an access candidate. On the other hand, if the IAB support information (= true) is not associated with the identified PLMN identifier in the PLMN identifier information list, the IAB node <NUM> determines that the IAB access to the cell (the NPN to which the cell belongs) is prohibited, and does not regard the cell as an access candidate.

In an operation pattern 2c, the PLMN identifier information list is configured to include the NPN identifier. Specifically, in the operation pattern 2c, the PLMN identifier information list includes the IAB support information associated with at least one of the PLMN identifier or the NPN identifier included in the PLMN identifier information list. In this manner, moving the NPN identifier to the PLMN identifier information list makes it possible to achieve the IAB access control similar to the PLMN identifier.

<FIG> is a diagram illustrating an example of the PLMN identifier information list in the SIB1 in the operation pattern 2c.

As illustrated in <FIG>, the PLMN identifier information list (PLMN-Identity InfoList) in the SIB1 in the operation pattern 2c includes one or more PLMN identifier information elements (PLMN-IdentityInfo). The PLMN identifier information elements include an identifier list (PLMN-IdentityList) containing PLMN-NPN-Identity as one or more PLMN identifiers and/or one or more NPN identifiers.

In the operation pattern 2c, PLMN-IdentityList includes the IAB support information (iab-Support) associated with the PLMN identifier or the NPN identifier.

To make the IAB access to the selected NPN, first, the IAB node <NUM> determines whether the NPN identifier of the selected NPN is included in PLMN-IdentityList included in the SIB1 broadcast in the cell. If the NPN identifier of the selected NPN is not included in PLMN-IdentityList, the IAB node <NUM> excludes the cell from the access candidate.

Second, if the NPN identifier of the selected NPN is included in PLMN-IdentityList, the IAB node <NUM> determines whether the IAB support information (= true) is associated with the NPN identifier.

Variations of the embodiment described above will be described.

The SIB1 may include access control information to prohibit access to the cell. Such access control information includes at least one of cellReservedForOtherUse, cellReservedForOperatorUse, or cellReservedForFutureUse. As illustrated in <FIG> and <FIG>, these pieces of information are information elements included in CellAccessRelatedInfo.

cellReservedForOtherUse is cell-specific information. cellReservedForOtherUse is, for example, information used for access restrictions when the cell (gNB <NUM>) is under maintenance. If cellReservedForOtherUse is "true", the UE <NUM> of release <NUM> of the 3GPP standard determines that access to the cell is prohibited, and does not regard the cell as an access candidate.

cellReservedForOtherUse is an information element introduced at release <NUM> of the 3GPP standard. The NPN described above is a technique that is introduced at release <NUM> of the 3GPP standard, and the UE <NUM> not supporting release <NUM> (i.e., the UE <NUM> of release <NUM>) cannot utilize the NPN. Therefore, in order to prohibit access of the UE <NUM> of release <NUM>, the NPN cell configures cellReservedForOtherUse with "true". Note that the UE <NUM> of release <NUM> of the 3GPP standard, specifically, the UE <NUM> supporting the NPN ignores cellReservedForOtherUse.

cellReservedForOperatorUse is PLMN-specific or NPN-specific information. cellReservedForOperatorUse is, for example, information used for access restrictions when the cell (gNB <NUM>) is used by an operator. If cellReservedForOperatorUse is "reserved", the UE <NUM> determines that access to the cell is prohibited, and does not regard the cell as an access candidate. On the other hand, if cellReservedForOperatorUse is "notReserved", the UE <NUM> determines that access to the cell is permitted, and regards the cell as an access candidate. cellReservedForOperatorUse is the information element introduced at release <NUM> of the 3GPP standard.

cellReservedForFutureUse is cell-specific information. cellReservedForFutureUse is, for example, information used for access restrictions when the cell (gNB <NUM>) is under maintenance. In a case that cellReservedForFutureUse is "true", the UE <NUM> determines that access to the cell is prohibited, and does not regard the cell as an access candidate.

cellReservedForFutureUse is the information element introduced at release <NUM> of the 3GPP standard. The NPN cell configures cellReservedForOtherUse to "true" as described above, so cellReservedForOtherUse cannot be used in the original application (e.g., application for indicating whether under maintenance). Therefore, cellReservedForFutureUse is introduced as a new information element in place of cellReservedForOtherUse. The UE <NUM> of release <NUM> of the 3GPP standard cannot interpret cellReservedForFutureUse, but the UE <NUM> of release <NUM> of the 3GPP standard can interpret cellReservedForFutureUse.

On such an assumption, the IAB node <NUM> may be considered as an infrastructure-side apparatus, and thus the IAB node <NUM> may possibly ignore cellReservedForOtherUse and cellReservedForOperatorUse. Note that IAB is a technique that is introduced at release <NUM> of the 3GPP standard. In an embodiment, the IAB node <NUM> may also possibly ignore cellReservedForFutureUse. In the following, cellReservedForFutureUse is primarily assumed as an example of the access control information, but the access control information may be at least one of cellReservedForOtherUse or cellReservedForOperatorUse.

<FIG> is a flow chart illustrating a communication control method according to the modification example.

As illustrated in <FIG>, in step S11, the gNB <NUM> managing the NPN cell broadcasts, in the NPN cell, the SIB1 including the CellAcessRelatedInfo as illustrated in <FIG>. CellAccessRelatedInfo includes the NPN identifier information list (NPN-IdentityInfoList) and the access control information (cellReservedForFutureUse). The access control information may be associated with the NPN identifier included in the SIB1.

In step S12, the IAB node <NUM> receives the SIB1 from the gNB <NUM>.

In step S13, the IAB node <NUM> determines whether a predetermined condition is met. If the access control information is associated with the NPN identifier, it may be determined whether access is permitted for the NPN indicated by the NPN identifier, based on the access control information associated with the NPN identifier.

The predetermined condition includes at least one of the following conditions. Specifically, the IAB node <NUM> may determine that the predetermined condition is met when one of the following conditions is met, or may determine that the predetermined condition is met when a combination of two or more conditions of the following conditions is met.

If YES in step S13, in other words, if the predetermined condition is met, the IAB node <NUM> ignores the access control information included in the SIB1. This allows the IAB node <NUM> to determine that the IAB access to the NPN cell is permitted even when cellReservedForFutureUse (= true) is included in the SIB1 broadcast in the NPN cell, for example.

On the other hand, if NO in step S13, in other words, if the predetermined condition is not met, the IAB node <NUM> applies the access control information included in the SIB1. This allows the IAB node <NUM> to determine that the IAB access to the NPN cell is prohibited when cellReservedForFutureUse (= true) is included in the SIB1 broadcast in the NPN cell, for example.

In the above-described embodiment, an example in which the relay node is the IAB node <NUM> is described. However, the relay node may be relay UE. <FIG> is a diagram illustrating a variation of the cellular communication system <NUM>. As illustrated in <FIG>, the cellular communication system <NUM> includes the 5GC <NUM>, the gNBs <NUM>-<NUM> and <NUM>-<NUM>, remote UE <NUM>-<NUM>, and relay UE <NUM>-<NUM>. The relay UE <NUM>-<NUM> is an example of the relay node. The remote UE <NUM>-<NUM> is an example of a lower node, and the gNB <NUM>-<NUM> is an example of an upper node. The remote UE <NUM>-<NUM> communicates with the relay UE <NUM>-<NUM> via a PC5 interface (sidelink) that is an inter-UE interface. The relay UE <NUM>-<NUM> communicates with the gNB <NUM>-<NUM> via an NR Uu wireless interface. As a result, the remote UE <NUM>-<NUM> indirectly communicates with the gNB <NUM>-<NUM> via the relay UE <NUM>-<NUM>.

In the embodiment described above, an example has been mainly described, in which the cellular communication system <NUM> is a <NUM> cellular communication system. However, the base station in the cellular communication system <NUM> may be an eNB that is an LTE base station. The core network in the cellular communication system <NUM> may be an Evolved Packet Core (EPC). The gNB can be connected to the EPC, the eNB can be connected to the 5GC, and the gNB and the eNB may be connected via an inter-base station interface (Xn interface, X2 interface).

A program may be provided to cause a computer to execute the processing operations according to the embodiments described above. The program may be recorded in a computer-readable medium. Use of the computer readable medium enables the program to be installed on a computer. Here, the computer readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM, a DVD-ROM, or the like. A chip set may be provided that includes a memory that stores a program for executing each of the processing operations performed by the UE <NUM>, the gNB <NUM>, or the IAB node <NUM> and a processor that executes the program stored in the memory.

In a work item for the Integrated Access and Backhaul (IAB), defined are new entities, an IAB donor and an IAB node to enable NR multi-hop and topological networking. Since these entities are considered as network nodes, special processing of the access restrictions is agreed.

Another new wave of <NUM> deployment is to support a private network or the non-public network (NPN). This allows the NPN cell to be identified either by the PLMN ID and NID (for the SNPN) or the PLMN ID and CAG ID (for the PNI-NPN). It is agreed that these network identifiers are broadcast in the SIB1 as external to a legacy PLMN ID information list.

Rel-<NUM> supporting an IAB function even in the NPN deployment may be considered to be very important in a use case of smart factory that is rapidly growing, for example. Accordingly, this Supplementary Note discusses basic problems in the current agreement between two work items.

One of the primary requirements of Rel-<NUM> is to support various virtual domains, and one of the strong demands for the <NUM> deployment is coming from the smart factories. Therefore, a very large number of Rel-<NUM> WIs are intended to meet strict requirements for industrial use cases such as eURLLC and IIoT. In general, industrial users will require private networks for their own facilities to ensure specific security and performance requirements. This is deployed by private network, private slices, or the like. In our opinions, the IAB functions are also very useful in such industrial use cases using the private networks. For example, in the smart factories, the IAB can be deployed quickly with an efficient radio backhaul in an already operating facility, i.e., a retrofit. Consequently, RAN2 should agree to ensure the IAB support in the NPN deployment.

Proposal <NUM>: RAN2 should agree to ensure the IAB function even for the non-public network deployment.

In the approved CR for the IAB, the iab-SupportIE is provided in PLMN-IdentityInfoList in the SIB1, as follows.

PLMN-IdentityInfoList ::= SEQUENCE (SIZE (<NUM>. maxPLMN)) OF
PLMN-IdentityInfo
PLMN-IdentityInfo ::= SEQUENCE {
plmn-IdentityList SEQUENCE (SIZE (<NUM>. maxPLMN)) OF PLMN-
Identity,
trackingAreaCode OPTIONAL, -- Need R
ranac RAN-AreaCode OPTIONAL, -- Need R
cellIdentity,
cellReservedForOperatorUse ENUMERATED {reserved, notReserved},. ,
[[
iab-Support-r16 ENUMERATED {true} OPTIONAL -- Need R
]]
}.

The IAB-MT regards the cell as being barred unless the iab-Support IE is provided in the selected PLMN or the like.

Upon receiving the SIB1, the UE shall:
[.

On the other hand, PRN WI adds npn-IdentityInfoList to support the SNPN (Standalone NPN) and the Public Network Integrated NPN (PNI-NPN). However, because RAN2 agrees to "NPN information is outside PLMN-Identity InfoList as a new Rel-<NUM> IE for NPN-only cell and PLMN + NPN cell (the total number of network IDs is still <NUM>)", npn-IdentityInfoList is outside the known plmn-IdentityInfoList, as follows.

CellAccessRelatedInfo ::= SEQUENCE {
plmn-IdentityList PLMN-IdentityInfoList,
cellReservedForOtherUse ENUMERATED {true} OPTIONAL, -- Need
R. ,
[[
cellReservedForFutureUse-r16 ENUMERATED {true} OPTIONAL, --
Need R
npn-IdentityInfoList-r16 OPTIONAL -- Need R
]]
}.

Of course, new npn-IdentityInfoList is currently not included in iab-SupportIE, as follows.

NPN-IdentityInfoList-r16 ::= SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF
NPN-IdentityInfo-r16
NPN-IdentityInfo-r16 ::= SEQUENCE {
npn-IdentityList-r16 SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF NPN-
Identity-r16,
trackingAreaCode-r16 TrackingAreaCode,
ranac-r16 RAN-AreaCode OPTIONAL, -- Need R
cellIdentity-r16 CellIdentity, cellReservedForOperatorUse-r16
ENUMERATED {reserved, notReserved},. }
NPN-Identity-r16 ::= CHOICE {
pni-npn-r16 SEQUENCE {
plmn-Identity-r16 PLMN-Identity,
cag-IdentityList-r16 SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF CAG-
Identity-r16
},
snpn-r16 SEQUENCE {
plmn-Identity PLMN-Identity,
nid-List-r16 SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF NID-r16
}
}
CAG-Identity-r16 ::= BIT STRING (SIZE (<NUM>))
NID-r16 ::= BIT STRING (SIZE (<NUM>)).

Accordingly, the IAB-MT selecting the NPN regards the NPN cell as being always barred. This means that the IAB is not supported by the NPN deployment until now, but we believe that this is not an intended operation.

Finding <NUM>: The IAB-MT cannot access the NPN cell that is always regarded as being barred because there is no IAB support indication in an NPN identification information list.

In order to enable the IAB in the NPN, iab-Support IE should be added in npn-Identity InfoList. Further, the text of the procedure should be adapted to the case of the selected NPN. These changes are very simple, but large gain is obtained to broadly support various deployment scenarios of Rel-<NUM> NR.

Proposal <NUM>: RAN2 should agree to add iab-Support IE in npn-Identity InfoList.

Proposal <NUM>: RAN2 should agree to add the case of NPN in the text of the procedure of SIB1 reception for the iab-Support processing.

An example of implementing the proposals <NUM> and <NUM> in TS <NUM> is described in Appendix.

RAN2 agrees to "IAB-MT ignores cellBarred, cellReservedForOtherUse, and cellReservedForOperatorUse of the IE. Any problem, if defined, will be discussed in the next meeting. " On the other hand, PRN WI agrees to "cellReservedForOtherUse is used to prevent Rel-<NUM> UE from accessing the cell" and "a new Rel-<NUM> IE with a role similar to the role of cellReservedForOtherUse for Rel-<NUM> UE is cell specific. " As such, RAN2 created cellReservedForFutureUse, which is a new IE, for Cell AccessRelatedInfo. Therefore, in order to notify the UE of being the NPN cell, as follows, the NPN cell is considered to possibly broadcast the SIB1 along with cellReservedForOtherUse configured with "true" and npn-Identity InfoList.

The NPN cell, and also the PLMN cell depending on circumstances, may possibly broadcast cellReservedForFutureUse = "true" for some reason such as network maintenance. In this case, it is not clear how the IAB-MT operates. One interpretation is, because the IAB-MT is in agreement with the original usage of cellReservedForOtherUse in Rel-<NUM>, regarding the cell as being barred. On the other hand, because RAN2 agrees to "IAB-MT is not under UAC control", another interpretation may be taken that the IAB should also ignore cellReservedForFutureUse. In this case, the IAB-MT is a network node, and thus, may access any cell. From our perspective, any operation is acceptable, but should be made clear in this release for future calibration.

Proposal <NUM>: RAN2 should clarify whether the IAB-MT ignores cellReservedForFutureUse.

A variation for TS <NUM> for supporting the IAB in the NPN deployment is as follows.

NPN-IdentityInfoList-r16 ::= SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF
NPN-IdentityInfo-r16
NPN-IdentityInfo-r16 ::= SEQUENCE {
npn-IdentityList-r16 SEQUENCE (SIZE (<NUM>. maxNPN-r16)) OF NPN-
Identity-r16,
trackingAreaCode-r16 TrackingAreaCode,
ranac-r16 RAN-AreaCode OPTIONAL, -- Need R
cellIdentity-r16 CellIdentity,
cellReservedForOperatorUse-r16 ENUMERATED {reserved,
notReserved},. [[
iab-Support-r16 ENUMERATED {true} OPTIONAL -- Need R
]]
}.

Claim 1:
A communication control method used in a cellular communication system (<NUM>), the cellular communication system (<NUM>) comprising an IAB node (<NUM>) for relaying communication between a base station (<NUM>) and user equipment (<NUM>), the communication control method comprising:
broadcasting, by the base station (<NUM>) managing a cell belonging to a Non-Public Network, NPN, a system information block comprising an NPN identifier identifying the NPN to the cell;
receiving, by the IAB node (<NUM>), the system information block from the base station (<NUM>); and
determining, by the IAB node (<NUM>), whether an access from the IAB node (<NUM>) to the cell is permitted, based on the system information block, wherein
the system information block comprises an NPN identifier information list,
wherein the NPN identifier information list comprises the NPN identifier,
the determining comprises determining whether the access is permitted, based on whether the NPN identifier information list further comprises IAB node support information associated with the NPN identifier, wherein
the IAB node support information indicates that the cell supports the IAB node (<NUM>),
the system information block further comprises access control information cellReservedForOtherUse,
the communication control method further comprises:
ignoring the cellReservedForOtherUse by the IAB node (<NUM>), in response to satisfying, by the IAB node, a predetermined condition related to support of the NPN by the IAB node; and
using the cellReservedForOtherUse by the IAB node (<NUM>), in response to not satisfying, by the IAB node, the predetermined condition.