Patent Description:
The current <NUM>th Generation <NUM> system architecture is described in <NPL> <FIG> provides an illustration of the <NUM> system architecture from 3GPP TS <NUM> v1. The Next Generation NG application layer protocol used over the N2 interface for the control plane is called NG AP. In this document, the N2 interface in <FIG> will also be referred to as NG-C (NG control plane) interface, while the N3 interface will also be referred to as NG-U (NG user plane) interface.

In <NUM> and in Long Term Evolution LTE it may be possible to move a UE (also referred to as a wireless device) to the so-called inactive state. In this state, Access Stratum (AS) resources are removed. However, a UE context is kept/maintained in the Radio Access Network RAN. Also, to the Core Network CN, the UE is treated as active. Namely, the N2 and N3 interfaces (S1-C and S1-U for LTE) pertinent to UE communication are maintained. The UE, however, may behave as if it was in Idle mode, namely, the UE will not signal to the RAN except in specific cases, to denote special mobility events.

It is currently specified that the core network CN is not aware of whether a UE is in Inactive mode. Note that Inactive State and Inactive Mode are equivalently used to indicate a UE that is inactive. Therefore, the transition from inactive to active state in the RAN will be transparent to the CN.

In the downlink (DL), this means for the default solution that DL packets will be sent to the last node where the UE was connected (anchor RAN node). That node will then be responsible for initiating UE paging within the paging area that the UE is allowed to move in without notifying the network.

In the uplink (UL), this means that the UE may need to perform a RAN-level procedure to transition to active state to transmit data. In case the UE has moved to a different RAN node, this RAN node will most likely need to fetch the UE context from another RAN node, and if needed, notify the CN that the UE has moved to a new node.

If the UE moves outside the paging area, it may need to notify the network about the mobility so that the paging area can be updated. This procedure could trigger a RAN node relocation, or the RAN node can be kept.

The following RAN functions are envisioned:.

In order for these mechanisms to be enabled, the UE may need to be allocated a RAN identifier uniquely identifying the UE context in the RAN. In case there is any failure where it is not possible to retrieve the UE RAN context, it may be assumed that the RAN context can be rebuilt as would happen in the case of a new connection setup.

<FIG> illustrate principles involved in management of inactive state/mode UEs. In the inactive state shown in <FIG>, the UE is in a low power mode with discontinuous reception DRX (e.g., for milliseconds ms to hours), and a CN/RAN connection is kept/maintained between the CN and the anchor RAN node for the UE. In this state, the UE is allowed to move around in the local area without telling the network.

There may currently exist certain challenges with Inactive Mode UEs. In current LTE and <NUM> systems, the CN may need to deliver a Non-Access Stratum (NAS) packet to the UE while the UE is in Inactive mode. Upon reception of the NAS Packet Data Unit (PDU), the RAN would start paging the UE in Inactive mode, as shown in <FIG>.

However, the UE may not respond to the RAN paging, for example, because the UE is not in coverage of the paging RAN. This may mean that for a certain time the RAN will not be able to page the UE, i.e., the UE may not be able to move to active state to receive the NAS PDU.

As the CN is unaware of the fact the UE is inactive, it may start re-sending the NAS PDU. However, this may be inefficient because the RAN may still be in the process of paging the UE. If paging eventually succeeds, the RAN may be able to send the very first instance of the NAS PDU and also the re-sent NAS PDU(s) from the CN, and this may create unnecessary signalling and may complicate handling at the UE side.

Another problem could be that the RAN, after attempting in vain to contact the UE via paging, may send a NAS Non-Delivery Message to the CN. Such a message may be present both on the S1 Application Protocol (S1AP) and NG Application Protocol (NGAP). In this case, the CN may trigger removal of the RAN-CN interfaces for the UE (e.g., NG-U, NG-C). This, however, may be an inefficient decision because the UE may re-emerge from lack of coverage and it may reconnect to the network, in which case the network may need to re-establish the interfaces that were previously removed.

"<NPL> discusses new procedures relating to the RRC_INACTIVE state for <NUM> systems.

According to some embodiments of inventive concepts, a method of operating a radio access network (RAN) node may be provided. A packet data unit (PDU) may be received for a wireless device that is in an inactive state. Moreover, the PDU may be received from a core network (CN) node. The wireless device may be paged in
response to receiving the PDU, and a non-delivery message may be sent to the CN node in response to failure of the paging for the wireless device. Moreover, the non-delivery message may include an indication that the wireless device is in the inactive state.

According to some embodiments, by providing a non-delivery message including an indication that the wireless device is in the inactive state, the CN node may more efficiently handle PDU procedures when paging fails.

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in a constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings:.

Other embodiments, however, are contained within the scope of the subject matter disclosed herein, and the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

A problem triggering behaviours discussed above may be that the CN, in cases of delayed or failed delivery of NAS PDUs, is not aware of whether the UE is inactive or not. According to some embodiments, knowledge of whether the UE is inactive or not may enable the CN to adopt smart procedures, for example, aimed at better handling retransmissions, interface removal, and/or other communication processing.

The claimed invention corresponds to <FIG>, <FIG> and to the related text in the description. The remaining figures and the text of the description are intended to better explain the invention.

Certain aspects of the present disclosure and their embodiments may provide solutions to these and/or other challenges. In this disclosure, upon failure in contacting the UE for the delivery of a NAS PDU, the RAN may inform the CN of the fact that the NAS PDU was not delivered and that the UE is in an Inactive state. According to certain embodiments, the RAN may also indicate if the CN shall refrain from sending the NAS PDU delivery (including re-sending) for a certain period in case the RAN considers the paging load is high or the paging shall not be re-tried in a certain period of time after several times of paging failure at RAN side.

There are, proposed herein, various embodiments which may address one or more of the issues disclosed herein. Certain embodiments may provide one or more of the following technical advantages. Some embodiments may allow the radio access network RAN node 460a (e.g., gNB) to remove a radio leg that is unstable (e.g., subject to frequent outages) while reducing/minimizing cases when the wireless device UE <NUM> is left without connectivity. Some embodiments may also provide a way for the RAN node 460a to convey useful/necessary information to the CN node 460b to make a proper decision on handling of NAS PDU procedure, when RAN paging fails. Other technical advantages may also be provided, and certain embodiments may provide some, none, or all of the advantages listed above.

According to certain embodiments, when a wireless device UE <NUM> is in the Inactive state and the CN node 460b needs to contact the wireless device UE <NUM> by sending to it a NAS PDU, the CN node 460a will forward the NAS PDU to the RAN node 460a. At this point the RAN node 460a will attempt to contact the wireless device UE <NUM> and let the wireless device UE <NUM> move to Active state.

As part of this embodiment, the CN node 460b may not re-send the NAS PDU until the RAN node 460a has responded to the CN node 460b in a specific manner, including, but not limited to the following:.

According to certain embodiments, the RAN node 460a will try to reach the wireless device UE <NUM> for a preconfigured time. If the wireless device UE <NUM> is not reachable (e.g., the wireless device UE <NUM> does not respond to RAN paging and the RAN node 460a cannot send the NAS PDU to the wireless device UE <NUM>), the RAN node 460a will generate a NAS Non-Delivery message that is transmitted towards the CN node 460b. Such a NAS Non-Delivery Message will contain an indication that the wireless device UE <NUM> is in an inactive state.

The CN node 460b receiving the NAS Non-Delivery message may take into account the Inactive State notification to make an appropriate decision, including, but not limited to the following:.

A Message sequence chart illustrating a method according to some embodiments is provided in <FIG>.

Operation <NUM>. Wireless device UE <NUM> enters CM-CONNECTED and RRC Inactive state. Access and Mobility Function (AMF) CN node 460b maintains wireless device UE <NUM> at CM-CONNECTED state and is unaware that the wireless device UE <NUM> is in the inactive state (i.e., treats the wireless device UE <NUM> as being active). The RAN node 460a maintains the wireless device UE <NUM> context after the wireless device UE <NUM> enters the inactive state.

Operation <NUM>. AMF CN node 460b sends a DL NAS PDU for the inactive state wireless device UE <NUM> on the existing NG-C connection for the inactive state wireless device UE <NUM> towards RAN node 460b.

Operation <NUM>. RAN node 460b initiates paging the inactive state wireless device UE <NUM> based on a local formulated paging profile.

Operation <NUM>. Due to whatever reason, the inactive state wireless device UE <NUM> may fail to respond to the RAN paging.

Operation <NUM>. When RAN node 460a considers that paging has failed after paging timeout and no wireless device UE <NUM> response is received, RAN node 460a sends a NAS Non-Delivery Message (also referred to as a NAS Non-Delivery Indication) to AMF CN node 460b indicating the failure and may also include the current wireless device UE <NUM> RRC state info and an indication if NAS PDU shall be refrained for a certain time.

Operation <NUM>. AMF CN node 460b may take different actions based on the info received from RAN node 460a, as described above.

It will be appreciated that the message sequence shown in <FIG> is for purposes of example, and other embodiments may modify the steps and/or order of the steps without deviating from the scope of inventive concepts. Furthermore, it will be appreciated that the RAN Node 460a and AMF CN node 460b may be embodied in any suitable network node (e.g., gNB, MME, etc.) as described in more detail below.

Operations of RAN node 460a (e.g., a base station, eNB, gNB, etc.) of a wireless communication network will now be discussed with reference to the flow chart of <FIG>. For example, RAN node 460a may be implemented using structure of network node <NUM> from <FIG> with instructions stored in device readable medium <NUM> of RAN node 460a so that when instructions of device readable medium <NUM> of RAN node 460a are executed by processing circuitry <NUM> of RAN node 460a, processing circuitry <NUM> of RAN node 460a performs respective operations discussed below with respect to <FIG>. Processing circuitry <NUM> of RAN node 460a may thus transmit and/or receive communications to/from one or more other network nodes/entities/servers of a wireless communication network (e.g., CN node 460b) through interface <NUM> of RAN node 460a (e.g., using port(s)/terminal(s) <NUM>). In addition, processing circuitry <NUM> of RAN node 460a may transmit and/or receive communications to/from one or more wireless devices (e.g., wireless device UE <NUM>) through interface <NUM> of RAN node 460a (e.g., using RF transceiver circuitry <NUM>, baseband circuitry <NUM>, and/or radio front end circuitry <NUM>).

At block <NUM>, processing circuitry <NUM> of RAN node 460a may maintain a context for wireless device <NUM> in the inactive state as discussed above, for example, with respect to operation <NUM> of <FIG>. The inactive state may be a Radio Resource Control RRC inactive state, and wireless device <NUM> may be in a CM-Connected and RRC inactive state.

At block <NUM>, processing circuitry <NUM> of RAN node 460a may receive a packet data unit PDU (e.g., a non-access stratum NAS PDU) for wireless device <NUM> that is in the inactive state as discussed above, for example, with respect to operation <NUM> of <FIG>. For example, processing circuitry <NUM> of RAN node 460a may receive the PDU from core network CN node 460b through interface <NUM> of RAN node 460a (e.g., using port(s)/terminal(s) <NUM>). CN node 460b, for example, may be an Access and Mobility Function AMF node.

At block <NUM>, processing circuitry <NUM> of RAN node 460a may page wireless device <NUM> in response to receiving the PDU as discussed above, for example, with respect to operation <NUM> of <FIG>. For example, processing circuitry <NUM> of RAN node 460a may transmit one or more pages for wireless device <NUM> through interface <NUM> of RAN node 460a (e.g., using baseband circuitry <NUM>, RF transceiver circuitry <NUM>, and/or radio front end circuitry <NUM>).

At block <NUM>, processing circuitry <NUM> of RAN node 460a may send a non-delivery message (e.g., a NAS non-delivery message) to CN node 460b in response to failure of the paging for wireless device <NUM> as discussed above, for example, with respect to operation <NUM> of <FIG>. Moreover, the non-delivery message may include an indication that wireless device <NUM> is in the inactive state. For example, processing circuitry <NUM> of RAN node 460a may send the non-delivery message to CN node 460b through interface <NUM> of RAN node 460a (e.g., using port(s)/terminal(s) <NUM>). The non-delivery message may indicate that the PDU was not delivered to wireless device <NUM>.

The non-delivery message may include an instruction for CN node 460b to refrain from resending the PDU for wireless device <NUM>. For example, the instruction for CN node 460b to refrain from resending may be an instruction for CN node 460b to refrain from resending the PDU for wireless device <NUM> for a period of time following the non-delivery message. Moreover, the non-delivery message may include the instruction for the node of the CN to refrain from resending the PDU for wireless device <NUM> in response to a high paging load and/or in response to multiple failures of paging for wireless device <NUM>.

The failure of the paging may be determined in response to failure to receive a response from wireless device <NUM> at RAN node 460a after initiating the paging. For example, the failure of the paging may be determined in response to failure to receive a response from wireless device <NUM> at RAN node 460a for a preconfigured time after initiating the paging.

Various operations of <FIG> may be optional with respect to some embodiments. For example, operations of block <NUM> of <FIG> may be optional according to some embodiments.

Operations of CN node 460b (e.g., an AMF node) of a wireless communication network will now be discussed with reference to the flow chart of <FIG>. For example, CN node 460b may be implemented using structure of network node <NUM> from <FIG> with instructions stored in device readable medium <NUM> of CN node 460b so that when instructions of device readable medium <NUM> of CN node 460b are executed by processing circuitry <NUM> of CN node 460b, processing circuitry <NUM> of CN node 460b performs respective operations discussed below with respect to <FIG>. Processing circuitry <NUM> of CN node 460b may thus transmit and/or receive communications to/from one or more other network nodes/entities/servers of a wireless communication network (e.g., RAN node 460a) through interface <NUM> of CN node 460b (e.g., using port(s)/terminal(s) <NUM>). Because CN node 460b may communicate indirectly with wireless devices through one or more RAN nodes, RF transceiver circuitry <NUM>, baseband circuitry <NUM>, and/or radio front end circuitry <NUM> of <FIG> may be omitted from CN node 460b.

At block <NUM>, processing circuitry <NUM> of CN node 460b may send a packet data unit PDU (e.g., a non-access stratum NAS PDU) for wireless device <NUM> to radio access network RAN node 460a (e.g., a base station) as discussed above, for example, with respect to operation <NUM> of <FIG>. Processing circuitry <NUM> of CN node 460b may send the PDU for wireless device <NUM> to RAN node 460a through interface <NUM> of CN node 460b (e.g., using port(s)/terminal(s) <NUM>).

At block <NUM>, processing circuitry <NUM> of CN node 460b may receive a non-delivery message (e.g., a NAS non-delivery message) from RAN node 460a after sending the PDU for wireless device <NUM> as discussed above, for example, with respect to operation <NUM> of <FIG>. Processing circuitry <NUM> of CN node 460b may receive the non-delivery message from RAN node 460a through interface <NUM> of CN node 460b (e.g., using port(s)/terminal(s) <NUM>). Moreover, the non-delivery message may include an indication that wireless device <NUM> is in an inactive state (e.g., a CM-connected and Radio Resource Control RRC inactive state). Moreover, the non-delivery message may indicate that the PDU was not delivered to wireless device <NUM>.

The non-delivery message may include an instruction for CN node 460b to refrain from resending the PDU for wireless device <NUM>. For example, the instruction for CN node 460b to refrain from resending may be an instruction for CN node 460b to refrain from resending the PDU for wireless device <NUM> for a period of time following the non-delivery message.

At block <NUM>, processing circuitry <NUM> of CN node 460b may act responsive to the non-delivery message as discussed above, for example with respect to operation <NUM> of <FIG>.

According to some embodiments at block <NUM>, processing circuitry <NUM> of CN node 460b may remove an interface for wireless device <NUM> between RAN node 460a and the core network in response to the non-delivery message. Removing an interface, for example, may include removing at least one of a Next Generation Control Plane (NG-C) interface and an NG User Plane (NG-U) interface for wireless device <NUM> in response to the non-delivery message.

According to some other embodiments at block <NUM>, processing circuitry <NUM> of CN node 460b may refrain from resending the PDU for wireless device <NUM> in response to the non-delivery message. Processing circuitry <NUM> of CN node 460b may refrain from resending the PDU by refraining from resending the PDU for a period of time following the non-delivery message, and then resending the PDU after the period of time following the non-delivery message.

According to still other embodiments at block <NUM>, processing circuitry <NUM> of CN node 460b may send a request to RAN node 460a in response to the non-delivery message, and the request may include a request for at least one parameter regarding wireless device <NUM> when wireless device <NUM> communicates with the radio access network. For example, the at least one parameter regarding wireless device <NUM> may include at least one of a parameter regarding a location of wireless device <NUM> and a parameter regarding a state of wireless device <NUM>.

<FIG> is a diagram illustrating a wireless network in accordance with some embodiments of inventive concepts.

Although the subject matter described herein may be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a wireless network, such as the example wireless network illustrated in <FIG>. For simplicity, the wireless network of <FIG> only depicts network <NUM>, network nodes <NUM> and 460b, and WDs <NUM>, 410b, and 410c. In practice, a wireless network may further include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or end device. Of the illustrated components, network node <NUM> and wireless device (WD) <NUM> are depicted with additional detail. The wireless network may provide communication and other types of services to one or more wireless devices to facilitate the wireless devices' access to and/or use of the services provided by, or via, the wireless network.

Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, and evolved Node Bs (eNBs)).

It is to be understood that a network node comprises any suitable combination of hardware and/or software used/needed to perform the tasks, features, functions and methods disclosed herein.

Alternative embodiments of network node <NUM> may include additional components beyond those shown in <FIG> that may be responsible for providing certain aspects of the network node's functionality, including any of the functionality described herein and/or any functionality useful/necessary to support the subject matter described herein.

As used herein, wireless device (WD) refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other wireless devices. Unless otherwise noted, the term WD may be used interchangeably herein with user equipment (UE). Communicating wirelessly may involve transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information through air. In some embodiments, a WD may be configured to transmit and/or receive information without direct human interaction. For instance, a WD may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the network. Examples of a WD include, but are not limited to, a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless cameras, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer-premise equipment (CPE), a vehicle-mounted wireless terminal device, etc. A WD may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, and may in this case be referred to as a D2D communication device. As yet another specific example, in an Internet of Things (IoT) scenario, a WD may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another WD and/or a network node. The WD may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the WD may be a UE implementing the 3GPP narrow band internet of things (NB-loT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances (e.g. refrigerators, televisions, etc.) personal wearables (e.g., watches, fitness trackers, etc.). In other scenarios, a WD may represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation. A WD as described above may represent the endpoint of a wireless connection, in which case the device may be referred to as a wireless terminal. Furthermore, a WD as described above may be mobile, in which case it may also be referred to as a mobile device or a mobile terminal.

<FIG> is a diagram illustrating a user Equipment in accordance with some embodiments of inventive concepts.

Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user. A UE may also comprise any UE identified by the <NUM>rd Generation Partnership Project (3GPP), including a NB-loT UE that is not intended for sale to, or operation by, a human user.

Network connection interface <NUM> may be configured to provide a communication interface to network 543a. Network 543a may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 543a may comprise a Wi-Fi network.

In <FIG>, processing circuitry <NUM> may be configured to communicate with network 543b using communication subsystem <NUM>. Network 543a and network 543b may be the same network or networks or different network or networks. Communication subsystem <NUM> may be configured to include one or more transceivers used to communicate with network 543b.

Network 543b may encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 543b may be a cellular network, a Wi-Fi network, and/or a near-field network.

<FIG> is a diagram illustrating a virtualization environment in accordance with some embodiments of inventive concepts.

<FIG> is a diagram illustrating a
telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments of inventive concepts.

Access network <NUM> comprises a plurality of base stations 712a, 712b, 712c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 713a, 713b, 713c. Each base station 712a, 712b, 712c is connectable to core network <NUM> over a wired or wireless connection <NUM>. A first UE <NUM> located in coverage area 713c is configured to wirelessly connect to, or be paged by, the corresponding base station 712c. A second UE <NUM> in coverage area 713a is wirelessly connectable to the corresponding base station 712a.

<FIG> is a diagram illustrating a host computer communicating via a base station with a user equipment over a partially wireless connection in accordance with some embodiments of inventive concepts.

It is noted that host computer <NUM>, base station <NUM> and UE <NUM> illustrated in <FIG> may be similar or identical to host computer <NUM>, one of base stations 712a, 712b, 712c and one of UEs <NUM>, <NUM> of <FIG>, respectively.

Wireless connection <NUM> between UE <NUM> and base station <NUM> is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to UE <NUM> using OTT connection <NUM>, in which wireless connection <NUM> forms the last segment. More precisely, the teachings of these embodiments may improve the latency and power consumption and thereby provide benefits such as reduced signaling, reduced user waiting time, better responsiveness, and extended battery lifetime.

<FIG> is a flow chart illustrating methods implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments of inventive concepts.

<FIG> methods implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments of inventive concepts.

Claim 1:
A method of operating a radio access network, RAN, node (460a), the method comprising:
receiving (<NUM>, <NUM>) a packet data unit, PDU, for a wireless device (<NUM>) that is in an inactive state, wherein the PDU is received from a core network, CN, node (460b);
paging (<NUM>, <NUM>) the wireless device (<NUM>) in response to receiving the PDU; and characterized in sending (<NUM>, <NUM>) a non-delivery message to the CN node in response to failure of the paging for the wireless device, wherein the non-delivery message includes an indication that the wireless device is in the inactive state, wherein the PDU is a non-access stratum, NAS, PDU, and wherein the non-delivery message is a NAS non-delivery message.