Switch to RRC connected state

Abstract

A first apparatus 120a (Receiving gNB) receiving a first message 307 from a second apparatus 120b (Anchor gNB). The message indicating to request a user equipment 150 to switch to a RRC connected stat

Description

FIELD

[0001] Various example embodiments relate generally to wireless networks and, more particularly, to fast resumption from a small data transmission (SDT) state to a connected state. BACKGROUND

[0002] Small data transmission (SDT) is a procedure allowing data and / or signaling transmission while remaining in a radio resource control inactive (RRC IXACT1VE) state (e.g., without transitioning to an RRC connected state). SDT is enabled on a radio bearer basis and is initiated by a user equipment (UE) depending on a number of factors (e.g., less than a configured amount of uplink (UL) data awaits transmission across all radio bearers for which SDT is enabled, downlink reference signal received power (DL RSRP) is above a configured threshold, and / or a valid SDT resource is available. However, in situations, the UE may need to switch from the RRC inactive state to the RRC connected state for communications. SUMMARY

[0003] In an aspect of the present disclosure, a method includes receiving, by a first apparatus, a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus. The first apparatus generates an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state, and transmits the RRC setup message to the UE in the RRC inactive state

[0004] In an aspect of the method, the first message is an Xn application protocol (XnAP) retrieve UE context response message.

[0005] In an aspect of the method, the indicating that the UE is requested to switch to the RRC connected state includes at least one of the following: indicating an end to the SDT procedure, indicating that a downlink data size in a buffer exceeds a data size for SDT transmission, indicating that a non-SDT transmission is to be transmitted, or indicating a request or a need to switch to RRC connected state.

[0006] In an aspect of the method, the first message is received based on an amount of uplink SDT data exceeding a threshold or non-SDT data is to be transmitted.

[0007] In an aspect of the method, the first message is received based on an RRC message, from the user equipment to the second apparatus, indicating that an amount of uplink SDT data exceeding a threshold or uplink non-SDT data is to be transmitted.

[0008] In an aspect of the method, the non-SDT transmission is for transmission on a radio bearer not configured for SDT transmission.

[0009] In an aspect of the method, the first apparatus generates the RRC setup message including the indication received from the second apparatus.

[0010] In an aspect of the method, the first apparatus is a receiving gNodeB involved in an SDT procedure.

[0011] In an aspect of the method, the second apparatus is an anchor gNodeB involved in an SDT procedure.

[0012] In an aspect of the method, the method includes receiving, by the first apparatus, a third message from the UE after transmitting the RRC setup message to the UE.

[0013] In an aspect of the method, the third message is an RRC setup complete message.

[0014] In an aspect of the method, the method includes receiving, by the first apparatus, an RRC release message included in the first message, and determining at least one of: terminating the SDT transaction and transmitting the RRC release message to the UE, or switching the UE to RRC connected state and generating and transmitting an RRC setup message to the UE.

[0015] In an aspect of the method, the RRC setup message causes the UE to move into the RRC connected state.

[0016] In an aspect of the present disclosure, a method includes receiving, by a second apparatus, from a user equipment in an RRC message or from a first apparatus in an XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment. The second apparatus, based on the received message, determines to switch the user equipment from an RRC inactive state to an RRC connected state, and transmits a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.

[0017] In an aspect of the present disclosure, a first apparatus includes at least one processor, and at least one memory storing instructions which, when executed by the at least one processor, cause the first apparatus at least to perform any of the foregoing methods.

[0018] In an aspect of the present disclosure, a second apparatus includes at least one processor, and at least one memory storing instructions which, when executed by the at least one processor, cause the second apparatus at least to perform any of the foregoing methods.

[0019] In an aspect of the present disclosure, a processor-readable medium storing instructions which, when executed by at least one processor of an apparatus, cause the apparatus at least to perform any of the foregoing methods.

[0020] In an aspect of the present disclosure, a first apparatus includes a memory, and a processor operatively coupled with and in communication with the memory. The processor is configured to: receive a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus, generate an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state, and transmit the RRC setup message to the UE in the RRC inactive state.

[0021] In an aspect of the present disclosure, a second apparatus includes a memory, and a processor operatively coupled with and in communication with the memory. The processor is configured to: receive from a user equipment in an RRC message or from a first apparatus in an XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment, determine based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state, and transmit a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.

[0022] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Some example embodiments will now be described with reference to the accompanying drawings.

[0024] FIG. 1 is a diagram of an example embodiment of wireless networking between a network system and a user equipment (UE), according to one illustrated aspect of the disclosure;

[0025] FIG. 2 is a diagram of example components of a network system, according to one illustrated aspect of the disclosure;

[0026] FIG. 3 is a diagram of an example embodiment of signals and operations among a UE, a receiving gNB, an anchor gNB, and a UPF, according to one illustrated aspect of the disclosure; and

[0027] FIG. 4 is a diagram of an example embodiment of components of a UE or of a network apparatus, according to one illustrated aspect of the present disclosure. DETAILED DESCRIPTION

[0028] In the following description, certain specific details are set forth in order to provide a thorough understanding of disclosed aspects. However, one skilled in the relevant art will recognize that aspects may be practiced without one or more of these specific details or with other methods, components, materials, etc. In other instances, well-known structures associated with transmitters, receivers, or transceivers have not been shown or described in detail to avoid unnecessarily obscuring descriptions of the aspects.

[0029] Reference throughout this specification to “one aspect” or “an aspect” means that a particular feature, structure, or characteristic described in connection with the aspect is included in at least one aspect. Thus, the appearances of the phrases “in one aspect” or “in an aspect” in various places throughout this specification are not necessarily all referring to the same aspect. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more aspects.

[0030] Embodiments described in the present disclosure may be implemented in wireless networking apparatuses, such as, without limitation, apparatuses utilizing Worldwide Interoperability for Microwave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, enhanced LTE (eLTE), 5G New Radio (5G NR), 5G Advance, 6G (and beyond) and 802.11 ax (Wi-Fi 6), among other wireless networking systems. The term ‘eLTE’ here denotes the LTE evolution that connects to a 5G core. LTE is also known as evolved UMTS terrestrial radio access (EUTRA) or as evolved UMTS terrestrial radio access network (EUTRAN).

[0031] The present disclosure may use the term “serving network device” to refer to a network node or network device (or a portion thereof) that services a UE. As used herein, the terms “transmit to,” “receive from,” and “cooperate with,” (and their variations) include communications that may or may not involve communications through one or more intermediate devices or nodes. The term “acquire” (and its variations) includes acquiring in the first instance or reacquiring after the first instance. The term “connection” may mean a physical connection or a logical connection.

[0032] The present disclosure uses 5G NR as an example of a wireless network and may use smartphones and / or extended reality headsets as an example of UEs. It is intended and shall be understood that such examples are merely illustrative, and the present disclosure is applicable to other wireless networks and user equipment.

[0033] FIG. 1 is a diagram depicting an example of wireless networking between a network system 100 and a user equipment (UE) 150. The network system 100 may include one or more network nodes 120, one or more servers 110, and / or one or more network equipment 130 (e.g., test equipment). The network nodes 120 will be described in more detail below. As used herein, the term “network apparatus” may refer to any component of the network system 100, such as the server 110, the network node 120, the network equipment 130, any component(s) of the foregoing, and / or any other component(s) of the network system 100. Examples of network apparatuses include, without limitation, apparatuses implementing aspects of 5GNR, among others. The present disclosure describes embodiments related to 5G NR and embodiments that involve aspects defined by 3rd Generation Partnership Project (3GPP). However, it is contemplated that embodiments relating to other wireless networking technologies are encompassed within the scope of the present disclosure.

[0034] The following description provides further details of examples of network nodes. In a 5G NR network, a gNodeB (also known as gNB) may include, e.g., a node that provides new radio (NR) user plane and control plane protocol terminations towards the UE and that is connected via a NG interface to the 5G core (5GC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 3.2, which is hereby incorporated by reference herein.

[0035] A gNB supports various protocol layers, e.g., Layer 1 (LI) - physical layer. Layer 2 (L2), and Layer 3 (L3).

[0036] 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.: o The physical layer offers to the MAC sublayer transport channels; o The MAC sublayer offers to the RLC sublayer logical channels; o The RLC sublayer offers to the PDCP sublayer RLC channels; o The PDCP sublayer offers to the SDAP sublayer radio bearers; o The SDAP sublayer offers to 5GC quality of sendee (QoS) flows; o Control channels include broadcast control channel (BCCH) and physical control channel (PCCH).

[0037] Layer 3 (L3) includes, e.g., radio resource control (RRC), e.g., according to 3GPP TS 38.300 V16.6.0 (2021-06) section 6, which is hereby incorporated by reference herein.

[0038] A gNB central unit (gNB-CU) includes, e.g., a logical node hosting, e.g., radio resource control (RRC), service data adaptation protocol (SDAP), and packet data convergence protocol (PDCP) protocols of the gNB or RRC and PDCP protocols of the en-gNB, that controls the operation of one or more gNB distributed units (gNB-DUs). The gNB-CU terminates the Fl interface connected with the gNB-DU A gNB-CU may also be referred to herein as a CU, a central unit, a centralized unit, or a control unit.

[0039] A gNB Distributed Unit (gNB-DU) includes, e.g., a logical node hosting, e.g., radio link control (RLC), media access control (MAC), and physical (PHY) 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 Fl interface connected with the gNB-CU. A gNB-DU may also be referred to herein as DU or a distributed unit.

[0040] As used herein, the term “network node” may refer to any of a gNB, a gNB-CU, or a gNB-DU, or any combination of them. A RAN (radio access network) node or network node such as, e.g., a gNB, 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 processor-readable instructions (“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. Different functional splits between the central and distributed unit are possible. An example of such an apparatus and components will be described in connection with FIG. 4 below.

[0041] 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 baseband unit / radio equipment controller / cloud-RAN / virtual-RAN (BBU / REC / C-RAN / V-RAN), open-RAN (O-RAN), or part thereof. A distributed unit (DU) may also be called remote radio head / remote radio unit / radio equipment / radio unit (RRH / RRU / REZRU), or part thereof. Hereinafter, in various example embodiments of the present disclosure, a network node, which supports at least one of central unit functionality or a layer 3 protocol of a radio access network, may be, e.g., a gNB-CU Similarly, a network node, which supports at least one of distributed unit functionality or a layer 2 protocol of the radio access network, may be, e.g., a gNB-DU.

[0042] A gNB-CU may support one or multiple gNB-DUs. A gNB-DU may support one or multiple cells and, thus, could support a serving cell for a user equipment (UE) or support a candidate cell for handover, dual connectivity, and / or carrier aggregation, among other procedures.

[0043] The user equipment (LIE) 150 may be or 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, or a M2M device, among other types of user equipment. Such UE 150 may include: at least one processor; and at least one memory including program code; where the at least one memory7 and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform certain operations, such as, e.g., RRC connection to the RAN. An example of components of a UE will be described in connection with FIG. 4. In embodiments, the UE 150 may be 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). In embodiments, the UE 150 may generate and transmit and receive RRC messages containing one or more RRC PDUs (packet data units). Persons skilled in the art will understand RRC protocol as well as other procedures a UE may perform.

[0044] With continuing reference to FIG. 1, in the example of a 5G NR network, the network system 100 provides one or more cells, which define a coverage area of the network system 100. As described above, the network system 100 may include a gNB of a 5G NR network or may include any other apparatus configured to control radio communication and manage radio resources within a cell. As used herein, the term “resource” may refer to radio resources, such as a resource block (RB), a physical resource block (PRB), a radio frame, a subframe, a time slot, a sub-band, a frequency region, a sub-carrier, a beam, etc. In embodiments, the network node 120 may be called a base station.

[0045] FIG. 1 provides an example and is merely illustrative of a network system 100 and a UE 150. Persons skilled in the art will understand that the network system 100 includes components not illustrated in FIG. 1 and will understand that other user equipment may be in communication with the network system 100.

[0046] FIG. 2 is a block diagram of example components of the network system 100 of FIG. 1. A 5G NR network may be described as an example of the network system 100, and it is intended that aspects of the following description shall be applicable to other types of network systems, as well. The network system may operate in accordance with the signals and connections shown in FIG. 1 such that the UE 150 is in communication with the network system 100 through the radio access network 225. Additionally, the network system may be divided into user plane components and functions and control plane components and functions, as shown and described herein. Unless indicated otherwise, the terms “component”, “function”, and “service” may be used interchangeably herein, and they may refer to and be implemented by instructions executed by one or more processors.

[0047] Example functions of the components are described below. The example functions are merely illustrative, and it shall be understood that additional operations and functions may be performed by the components described herein. Additionally, the connections between components may be virtual connections over service-based interfaces such that any component may communicate with any other component. In this manner, any component may act as a service “producer,” for any other component that is a service “consumer,” to provide services for network functions.

[0048] For example, a core network 210 is described in the control plane of the network system. The core network 210 may include an authentication server function (AUSF) 211, an access and mobility function (AMF) 212, and a session management function (SMF) 213. The core network 210 may also include a network slice selection function (NSSF) 214, a network exposure function (NEF) 215, a network repository function (NRF) 216, and a unified data management function (UDM) 217, which may include a uniform data repository (UDR) 224.

[0049] Additional components and functions of the core network 210 may include an application function 218, policy control function (PCF) 219, network data analytics function (NWDAF) 220, analytics data repository function (ADRF) 221, management data analytics function (MDAF) 222, and operations and management function (0AM) 223.

[0050] The user plane includes the UE 150, a radio access network (RAN) 225, a user plane function (UPF) 226, and a data network (DN) 227. The RAN 225 may include one or more components described in connection with FIG. 1, such as one or more network nodes. However, the RAN 225 may not be limited to such components. The UPF 226 provides connection for data being transmitted over the RAN 225. The DN 226 identifies services from service providers, Internet access, and third party services, for example.

[0051] The AMF 212 processes connection and mobility tasks. The AUSF 211 receives authentication requests from the AMF 212 and interacts with UDM 217 to authenticate and validate network responses for determination of successful authentication. The SMF 213 conducts packet data unit (PDU) session management, as well as manages session context with the UPF 226.

[0052] The NSSF 214 may select a network slicing instance (NSI) and determine the allowed network slice selection assistance information (NSSAI). This selection and determination is utilized to set the AMF 212 to provide service to the UE 150. The NEF 215 secures access to network services for third parties to create specialized network services. The NRF 216 acts as a repository to store network functions to allow the functions to register with and discover each other.

[0053] The UDM 217 generates authentication vectors for use by the AUSF 211 and ADM 212 and provides user identification handling. The UDM 217 may be connected to the UDR 224 which stores data associated with authentication, applications, or the like. The AF 218 provides application services to a user (e.g., streaming services, etc.). The PCF 219 provides policy control functionality. For example, the PCF 219 may assist in network slicing and mobility management, as well as provide quality of service (QoS) and charging functionality.

[0054] The NWDAF 220 collects data (e.g., from the UE 150 and the network system) to perform network analytics and provide insight to functions that utilize the analytics in the providing of services. The ADRF 221 allows the storage, retrieval, and removal of data and analytics by consumers. The MDAF 222 provides additional data analytics services for network functions. The 0AM 223 provides provisioning and management processing functions to manage elements in or connected to the network (e.g., UE 150, network nodes, etc.).

[0055] FIG. 2 is merely an example of components of a network system, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the network system may include other components not illustrated in FIG. 2. In embodiments, the network system may not include every component illustrated in FIG. 2. In embodiments, the components and connections may be implemented with different connections than those illustrated in FIG. 2. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0056] Although further detail is provided below, as mentioned above, in various embodiments, a UE may transmit traffic using small data transmission (SDT) procedure or SDT procedures when operating in a radio resource control (RRC) inactive state. The UE operating in the RRC inactive statein accordance with the SDT procedures may transmit data over a radio bearer, or bearers, configured for SDT communications.

[0057] As mentioned above, SDT is a procedure allowing data and / or signaling transmission while remaining in an RRC inactive state without transitioning to an RRC connected state. In various embodiments, SDT may be enabled on a radio bearer basis and can be initiated either by the UE in case of mobile originated SDT (MO-SDT) or by the network in case of mobile terminated SDT (MT-SDT). In various embodiments, MO-SDT is initiated by the UE if less than a configured amount of UL data awaits transmission across all radio bearers for which SDT is enabled, the downlink reference signal received power (DL RSRP) is above a configured threshold, and / or a valid SDT resource is available. In various example embodiments, the valid SDT resource may be understood as specified in clause 5.27.1 of TS 38.321. In various embodiments, MT-SDT may be initiated by the network with an indication to the UE in a paging message when DL data awaits transmission for radio bearers configured for SDT. Based on the indication, the UE may initiate the MT-SDT only if the DL RSRP is above a configured threshold.

[0058] In various embodiments, the UE may be in communication with a serving gNB (e.g., anchor gNB) that is providing the SDT communication capability to the UE. In various embodiments, the anchor gNB may be a last serving gNB for the UE. In various embodiments, the UE may move and cause the UE to communicate with another gNB (e.g., receiving gNB). The anchor gNB in this case may transfer control of the UE to the receiving gNB and provide the full context information about the UE to the receiving gNB. In various embodiments, this may be referred to as “SDT with UE context relocation” in accordance with section 18.2 of TS 38.300. In various embodiments, the anchor gNB may retain control of the UE and only perform a partial transfer of context information about the UE. In various embodiments, this may be referred to as “SDT without UE context relocation” in accordance with section 18.3 of TS 38.300.

[0059] In various example embodiments, it may be necessary for the UE to transition from the RRC inactive state to the RRC connected state. For example, in various embodiments, the anchor gNB may receive non-SDT downlink data to transmit (i.e. on a radio bearer not configured for SDT). In various embodiments, the anchor gNB may detect a large amount of downlink SDT data in its buffer to transmit that may exceed a threshold for SDT communication (e.g. amount of downlink data to be transmitted to the UE exceeds a threshold for SDT communication). In various embodiments, the anchor gNB may receive an indication from the UE that non-SDT uplink data is to be transmitted by the UE. In various embodiments, the anchor gNB may receive an indication that a large uplink SDT data size is to be transmitted by the UE (e.g. amount of uplink data to be transmitted by the UE exceeds a threshold for SDT communication).

[0060] Accordingly, although further detail is provided below, provided herein is a process to request a UE involved in an ongoing SDT procedure to switch from an RRC inactive state to an RRC connected state. That is, SDT procedure may be ongoing for the UE which is in RRC inactive state. In various embodiments, the process herein may relate to a UE being serviced by a receiving gNB with partial context, wherein the anchor gNB retains control over the UE (referred to as SDT without UE context relocation).

[0061] As used herein, a communication with a radio access network (RAN) may refer to and mean a communication with a portion of a RAN, such as with a network node (e g., a DU and / or a CU), or another portion of a RAN. As used herein, a communication with a core network may refer to and mean a communication with one or more services / applications of the core network, such as AMF or another service of a core network.

[0062] As used herein, in various embodiments, the term “receiving gNB” may refer to a gNB that is currently providing communication to the UE, while the term “anchor gNB” may be refer to a gNB that is a servicing gNB in communication with the receiving gNB. In various example embodiments, the term “apparatus”, “first apparatus”, “second apparatus”, or the like, may refer to any apparatus performing functions of communicating with the UE or another apparatus. In various example embodiments, the term “first apparatus” may refer to a receiving gNB and the term “second apparatus” may refer to an anchor gNB, or vice versa. In various embodiments, the term “UE” may be interchangeable with the term “mobile station” or “MS”. For example, in various embodiments, the term user equipment, or UE, may be used to identify a mobile station, or MS, connected to a network, or the term mobile station, or MS, may be used to identify a user equipment, or UE, connected to a network.

[0063] In accordance with the brief description, FIG. 3 is a diagram of an example embodiment of signals and operations among a UE, a receiving gNB, an anchor gNB, and a UPF, according to one illustrated aspect of the disclosure. The following paragraphs will describe various signals and operations. It will be understood that a described signal may have associated operations and a described operation may have associated signals.

[0064] As shown in FIG. 3, the UE may include UE 150 as described in FIG. 1, the gNBs may include network nodes 120 (designated 120a for the receiving gNB and 120b for the anchor gNB in FIG. 3), and the UPF may include the UPF 226 described in FIG. 2.

[0065] At operation 301, the UE is in the RRC inactive state. In various example embodiments, the UE may be engaged in an SDT transaction (i.e. SDT procedure involving multiple SDT transmissions) wherein data is transmitted between the UE and the gNB (e.g., anchor gNB) as described above. In various embodiments, the SDT procedure may be ongoing. In various example embodiments, the UE is in communication with the receiving gNB while the anchor gNB retains control (e.g., servicing of) the UE.

[0066] Accordingly, at operation 302, in order to engage the SDT procedure, the receiving gNB has earlier transmitted an Xn retrieve UE context request message to the anchor gNB and the anchor gNB has received the Xn retrieve UE context request message. Upon receiving the Xn retrieve UE context request, the anchor gNB, desiring (e.g., having a need) to retain control over the UE, at operation 303, has transmitted an Xn partial UE context transfer message to the receiving gNB and the receiving gNB has received the Xn partial transfer message.

[0067] The Xn partial transfer message includes partial context information relating to communicating with the UE. Upon receiving the Xn partial transfer message, at operation 304, the receiving gNB has transmitted an Xn partial UE context transfer acknowledge message to the anchor gNB and the anchor gNB has received the Xn partial UE context transfer acknowledge message. Persons of skill in the art will understand the contents of the messages transmitted at operations 302-304 used in the engagement of an SDT procedure referred to as “without UE context relocation” as per section 18.3 of TS 38.300. In various embodiments, operations 302-304 may have been performed upon the movement of the UE, causing the UE to communicate with the receiving gNB, with the anchor gNB desiring to retain control and servicing of the UE.

[0068] Accordingly, at operation 305, the UE that has been engaged in an SDT procedure with the anchor gNB as described above, continues with the receiving gNB remaining in communication with the UE.

[0069] As mentioned above, the anchor gNB may need to request the UE to switch from the RRC inactive state to the RRC connected state. For example, the anchor gNB may determine to request the UE to switch from the RRC inactive state to RRC connected state. For example, in various embodiments, the anchor gNB may receive non-SDT downlink data to transmit (i.e., on a radio bearer not configured for SDT). In various embodiments, the anchor gNB may detect a large amount of downlink SDT data in its buffer to transmit that may exceed a threshold for SDT communication. In various embodiments, the anchor gNB may receive an indication from the UE that non-SDT uplink data is to be transmitted by the UE. In various embodiments, the anchor gNB may receive an indication that a large uplink SDT data size is to be transmitted by the UE. The anchor gNB may be configured to determine the need to request the switch based on one or more of the aforementioned triggers (e.g. based on receiving non-SDT downlink data to transmit).

[0070] As shown in FIG. 3, in an example embodiment, at operation 306 the UPF transmits non SDT data to the anchor gNB for the UE and the anchor gNB receives the non SDT data. The reception of the non SDT data triggers the anchor gNB to request the UE to switch from the RRC inactive state to the RRC connected state. The operation depicted at operation 306 is exemplary and other conditions may occur that would cause the anchor gNB to request the UE to switch into RRC connected state. As mentioned above, the anchor gNB may detect a large amount of downlink SDT data in its buffer to transmit that may exceed a threshold for SDT communication. In various embodiments, the anchor gNB may receive an indication from the UE that non-SDT uplink data is to be transmitted by the UE. In various embodiments, the anchor gNB may receive an indication that a large uplink SDT data size is to be transmitted by the UE. Accordingly, persons of skill in the art will appreciate that operation 306 encompasses an example of triggering a switch to RRC connected state, but other conditions may also trigger the switch.

[0071] At operation 307, the anchor gNB transmits an Xn retrieve UE context response message (e.g., Xn application protocol (XnAP) retrieve UE context response message) to the receiving gNB and the receiving gNB receives the Xn retrieve UE context response message. In various embodiments, the Xn retrieve UE context response message includes one or more of the following indications: an end to the SDT procedure, a downlink data size in a buffer exceeding a data size for SDT transmission (e.g., exceeds the threshold for SDT transmission), a non-SDT transmission is to be transmitted, or a request / desire to switch to RRC connected state. The Xn retrieve UE context response message may be one example of a first message as used in this disclosure.

[0072] Based on the message (e.g. Xn retrieve UE context response) received from the anchor gNB, the receiving gNB generates an RRC setup message to be transmitted to the UE. For example, the generating the RRC setup message may be based on the indication or indications included in the message received from the anchor gNB. In general, the receiving gNB may generate the RRC setup message based on determining that the UE is to be switched from the RRC inactive state to an RRC connected state. As an example, upon receipt (or in response to reception) of the Xn retrieve UE context response message at operation 307, the receiving gNB generates, at operation 308, an RRC setup message based on the indication included in the Xn retrieve UE context response message. That is, for example, the receiving gNB generates (builds) the RRC setup message to transmit to the UE and which will cause the UE to switch / transition from the RRC inactive state to the RRC connected state for communication.

[0073] In various embodiments, the anchor gNB may transmit an RRC release message to the receiving gNB and the gNB may determine to terminate the SDT transaction procedure and transmit an RRC release message to the UE. In various embodiments, the receiving gNB may determine to switch the UE to the RRC connected state and generate and transmit an RRC setup message to the UE.

[0074] Accordingly, in various embodiments, at operation 309, the receiving gNB transmits the RRC setup message to the UE and the UE receives the RRC setup message. As discussed, the UE may in RRC inactive state when receiving the RRC setup message. Upon receipt of the RRC setup message, at operation 310, the UE transmits an RRC setup complete message to the receiving gNB and the receiving gNB receives the RRC setup complete message.

[0075] Accordingly, at operation 311, the UE operates in the RRC connected state. Persons of skill in the art will appreciate the process for the UE operating in the RRC connected state. That is, the RRC setup message may cause the UE to switch from the RRC inactive state to the RRC connected state.

[0076] The operations of FIG. 3 are merely illustrative, and variations are contemplated to be within the scope of the present disclosure. In embodiments, the operations may include other operations not illustrated in FIG. 3. In embodiments, the operations may not include every operation illustrated in FIG. 3. In embodiments, the operations may be implemented in a different order than that illustrated in FIG. 3. Such and other embodiments are contemplated to be within the scope of the present disclosure. Persons of skill in the art will appreciate that, although various example components are described as perform various functions, other components may perform those functions described in the method 300.

[0077] The following describes operations from the perspective of the receiving gNB. From such a perspective, the method includes receiving, by a first apparatus (e.g., the receiving gNB), a first message from a second apparatus (e.g., the anchor gNB), the first message indicating that a UE is requested to switch to an RRC connected state, for which an SDT procedure is ongoing in an RRC inactive state involving the user equipment, the first apparatus and the second apparatus. The first apparatus generates an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state, and transmits the RRC setup message to the UE in the RRC inactive state.

[0078] The following describes operation from the perspective of the anchor gNB. From such a perspective, the method includes receiving, from a user equipment in an RRC message or from a first apparatus (e.g., the receiving gNB) in an Xn AP message, an indication that an amount of uplink SDT data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment, determining, based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state, and transmitting a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus (e.g., the anchor gNB).

[0079] According to an embodiment, the first message (from anchor gNB to the receiving gNB) includes (or is denoted as) RRC release message. In such case, the receiving gNB may determine to perform at least one of following operations: terminating the SDT transaction and transmitting the RRC release message to the UE, or switching the UE to RRC connected state and generating and transmitting an RRC setup message to the UE. In an embodiment, the receiving gNB transmits either the received RRC release message or the RRC setup message based on the determining. For example, the former case may be simpler solution as RRC setup message may not need to be generated whereas the latter case may enable the UE to be switched faster from RRC inactive to RRC connected state.

[0080] Referring now to FIG. 4, there is shown a block diagram of example components of a UE or a network apparatus (e.g., of a RAN or a core network). The apparatus includes an electronic storage 410, a processor 420, a network interface 440, and a memory 450. The various components may be communicatively coupled with each other. The processor 420 may be and may include any type of processor, such as a single-core central processing unit (CPU), a multi-core CPU, a microprocessor, a digital signal processor (DSP), a System-on-Chip (SoC), or any other type of processor. The memory 450 may be a volatile type of memory, e.g., RAM, or a non-volatile type of memory, e.g., NAND flash memory. The memory 450 includes processor-readable instructions that are executable by the processor 420 to cause the apparatus to perform various operations, including those mentioned herein, such as the operations of FIG. 3.

[0081] The electronic storage 410 may be and include any type of electronic storage used for storing data, such as hard disk drive, solid state drive, optical disc, and / or other non-transitory computer-readable mediums, among other types of electronic storage. The electronic storage 410 stores processor-readable instructions for causing or configured for causing the apparatus to perform its operations and also stores data associated with such operations, such as storing data relating to 5G NR standards, among other data. The network interface 440 may implement wireless networking technologies such as 5G NR and / or other wireless networking technologies.

[0082] The components shown in FIG. 4 are merely examples, and persons skilled in the art will understand that an apparatus includes other components not illustrated and may include multiples of any of the illustrated components. Such and other embodiments are contemplated to be within the scope of the present disclosure.

[0083] Further embodiments of the present disclosure include the following examples.

[0084] Example 1.1. A first apparatus, comprising: means for receiving a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus; means for generating an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state; and means for transmitting the RRC setup message to the UE in the RRC inactive state.

[0085] Example 1.2. The first apparatus of example 1.1, wherein the first message is an Xn application protocol (XnAP) retrieve UE context response message.

[0086] Example 1.3. The first apparatus of example 1.1, wherein the indicating that the UE is requested to switch to the RRC connected state comprises at least one of the following: indicating an end to the SDT procedure, indicating that a downlink data size in a buffer exceeds a data size for SDT transmission, indicating that a non-SDT transmission is to be transmitted, or indicating a request or a need to switch to RRC connected state.

[0087] Example 1.4. The first apparatus as in any of examples 1.1-1.3, wherein the first message is received based on an amount of uplink SDT data exceeding a threshold or non-SDT data is to be transmitted.

[0088] Example 1.5. The first apparatus as in any of examples 1.1-1.4, wherein the first message is received based on an RRC message, from the user equipment to the second apparatus, indicating that an amount of uplink SDT data exceeding a threshold or uplink non-SDT data is to be transmitted.

[0089] Example 1.6. The first apparatus as in any of examples 1.4-1.5, wherein the non-SDT transmission is for transmission on a radio bearer not configured for SDT transmission.

[0090] Example 1.7. The first apparatus as in any of examples 1.3-1.6, wherein the first apparatus is configured to generate the RRC setup message including the indication received from the second apparatus.

[0091] Example 1.8. The apparatus as in any of examples 1.1-1.7, wherein the first apparatus is a receiving gNodeB involved in an SDT procedure.

[0092] Example 1.9. The first apparatus as in any of examples 1.1-1.8, wherein the second apparatus is an anchor gNodeB involved in an SDT procedure.

[0093] Example 1.10. The apparatus of example 1.1, wherein the first apparatus is configured to receive a third message from the UE after transmitting the RRC setup message to the UE.

[0094] Examplel.il. The first apparatus of example 1.10, wherein the third message is an RRC setup complete message.

[0095] Example 1.12. The first apparatus of example 1.1, wherein the first apparatus is configured to receive an RRC release message included in the first message, and determining at least one of: terminating the SDT transaction and transmitting the RRC release message to the UE, or switching the UE to RRC connected state and generating and transmitting an RRC setup message to the UE.

[0096] Example 1.13. The first apparatus of example 1.1 wherein the RRC setup message causes the UE to move into the RRC connected state.

[0097] Example 2.1. A second apparatus, comprising: means for receiving from a user equipment in an RRC message or from a first apparatus in an XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment; means for determining based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state; and means for transmitting a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.

[0098] Example 3.1. A first apparatus (e.g. receiving gNB), comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the first apparatus at least to perform: receiving a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus; generating an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state; and transmitting the RRC setup message to the UE in the RRC inactive state.

[0099] Example 4.1. A second apparatus (e.g. anchor gNB), comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the second apparatus at least to perform: receiving from a user equipment in an RRC message or from a first apparatus in an XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment; determining based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state; and transmitting a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.

[00100] The embodiments and aspects disclosed herein are examples of the present disclosure and may be embodied in various forms. For instance, although certain embodiments herein are described as separate embodiments, each of the embodiments herein may be combined with one or more of the other embodiments herein. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

[00101] For example, in various embodiments, an anchor gNB involved in an SDT procedure may be split into a central unit control plane (gNB-CU CP) and a central unit user plane (gNB-CU UP) and the gNB-CU UP may detect the that downlink data size in a buffer exceeds a data size for SDT transmission, and inform the gNB-CU CP that downlink data size in a buffer exceeds a data size for SDT transmission. The gNB-CU CP may trigger sending the transmission of a first message (e.g., the Xn retrieve UE context message) and of the indicating of the UE to switch to RRC connected state.

[00102] In various embodiments, an anchor gNodeB involved in an SDT procedure and split into a gNB-CU CP and a gNB-CU UP may include detecting, by the gNB-CU UP, that downlink non-SDT data or downlink data is to be transmitted, and informing the gNB-CU CP that downlink non-SDT data or downlink data is to be transmitted. The gNB-CU CP may trigger sending the transmission of a first message (e.g., the Xn retrieve UE context message) and of the indicating of the UE to switch to RRC connected state.

[00103] The phrases “in an aspect,” “in aspects,” “in various aspects,” “in some aspects,” or “in other aspects” may each refer to one or more of the same or different aspects in accordance with this present disclosure. The phrase “a plurality of’ may refer to two or more.

[00104] The phrases “in an embodiment,” “in embodiments,” “in various embodiments,” “in some embodiments,” or “in other embodiments” may each refer to one or more of the same or different embodiments in accordance with the present disclosure. A phrase in the form “A or B” means “(A), (B), or (A and B).” A phrase in the form “at least one of A, B, or C” means “(A); (B); (C); (A and B); (A and C); (B and C); or (A, B, and C)”

[00105] Any of the herein described methods, programs, algorithms or codes may be converted to, or expressed in, a programming language or computer program. The terms “programming language” and “computer program,” as used herein, each include any language used to specify instructions to a computer, and include (but is not limited to) the following languages and their derivatives: Assembler, Basic, Batch files, BCPL, C, C+, C++, Delphi, Fortran, Java, JavaScript, machine code, operating system command languages, Pascal, Perl, PL1, Python, scripting languages, Visual Basic, metalanguages which themselves specify programs, and all first, second, third, fourth, fifth, or further generation computer languages. Also included are database and other data schemas, and any other metalanguages. No distinction is made between languages which are interpreted, compiled, or use both compiled and interpreted approaches. No distinction is made between compiled and source versions of a program. Thus, reference to a program, where the programming language could exist in more than one state (such as source, compiled, object, or linked) is a reference to any and all such states. Reference to a program may encompass the actual instructions and / or the intent of those instructions.

[00106] While aspects of the present disclosure have been shown in the drawings, it is not intended that the present disclosure be limited thereto, as it is intended that the present disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular aspects. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. A method, comprising:receiving, by a first apparatus, a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus;generating, by the first apparatus, an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state; andtransmitting, by the first apparatus, the RRC setup message to the UE in the RRC inactive state.

2. The method of claim 1, wherein the first message is an Xn application protocol (XnAP) retrieve UE context response message.

3. The method of claim 1, wherein the indicating that the UE is requested to switch to the RRC connected state comprises at least one of the following: indicating an end to the SDT procedure, indicating that a downlink data size in a buffer exceeds a data size for SDT transmission, indicating that a non-SDT transmission is to be transmitted, or indicating a request or a need to switch to RRC connected state.

4. The method of any preceding claim, wherein the first message is received based on an amount of uplink SDT data exceeding a threshold or non-SDT data is to be transmitted.

5. The method of any preceding claim, wherein the first message is received based on an RRC message, from the user equipment to the second apparatus, indicating that an amount of uplink SDT data exceeding a threshold or uplink non-SDT data is to be transmitted.

6. The method as in any of claims 4 to 5, wherein the non-SDT transmission is for transmission on a radio bearer not configured for SDT transmission.

7. The method as in any of claims 3 to 6, wherein the first apparatus generates the RRC setup message including the indication received from the second apparatus.

8. The method of any preceding claims, wherein the first apparatus is a receiving gNodeB involved in an SDT procedure.

9. The method of any preceding claims, wherein the second apparatus is an anchor gNodeB involved in an SDT procedure.

10. The method of claim 1, further comprising receiving, by the first apparatus, a third message from the UE after transmitting the RRC setup message to the UE.

11. The method of claim 10, wherein the third message is an RRC setup complete message.

12. The method of claim 1, further comprising:receiving, by the first apparatus, an RRC release message included in the first message, and determining at least one of: terminating the SDT transaction and transmitting the RRC release message to the UE, or switching the UE to RRC connected state and generating and transmitting an RRC setup message to the UE.

13. The method of claim 1 wherein the RRC setup message causes the UE to move into the RRC connected state.

14. A method compri sing:receiving, by a second apparatus, from a user equipment in an RRC message or from a first apparatus in an XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment;determining, by the second apparatus, based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state; andtransmitting, by the second apparatus, a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC connectedstate, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.

15. A first apparatus, comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the first apparatus at least to perform a method as in any of claims 1-13.

16. A processor-readable medium storing instructions which, when executed by at least one processor of a first apparatus, cause the first apparatus at least to perform a method as in any one of claims 1-13.

17. A second apparatus, comprising:at least one processor; andat least one memory storing instructions which, when executed by the at least one processor, cause the second apparatus at least to perform a method as in claim 14.

18. A processor-readable medium storing instructions which, when executed by at least one processor of a second apparatus, cause the second apparatus at least to perform a method as in claim 14.

19. A first apparatus, comprising:a memory; anda processor operatively coupled with and in communication with the memory, the processor configured to:receive a first message from a second apparatus, the first message indicating that a user equipment (UE) is requested to switch to an RRC connected state, for which a small data transmission (SDT) procedure is ongoing in a radio resource control (RRC) inactive state involving the user equipment, the first apparatus and the second apparatus, generate an RRC setup message based on the indicating that the UE is requested to switch to the RRC connected state, and transmit the RRC setup message to the UE in the RRC inactive state.

20. A second apparatus, comprising:a memory; anda processor operatively coupled with and in communication with the memory, the processor configured to:receive from a user equipment in an RRC message or from a first apparatus in an 5 XnAP message, an indication that an amount of uplink small data transmission (SDT) data exceeding a threshold or uplink non-SDT data is to be transmitted by the user equipment, determine based on the received message, to switch the user equipment from an RRC inactive state to an RRC connected state, and transmit a first message to the first apparatus, the first message indicating that the user equipment is requested to switch to the RRC 10 connected state, for which an SDT procedure is ongoing in the RRC inactive state involving the user equipment, the first apparatus and the second apparatus.Application No: GB2315339.8Claims searched: 1-20Examiner: NishanthMuraleedharanDate of search: 26 March 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance v A 1-20 WO 2023 / 000315 Al (LENOVO) See figure 2, paragraphs 73-74, 78,81- 82. X 1-20 WO 2023 / 154401 Al (GOOGLE LLC) See figure 5 A, paragraphs 112 and 113. X 1-20 US 2019 / 0289661 Al (CHEN) See figure 6 and paragraph 45. X 1-20 3GPP TSG-RAN3 Meeting #119, Athens, Greece, Feb 27th - March 3rd, 2023, Qualcomm Incorporated, "Signaling enhancements to enable MT-SDT for RRC INACTIVE UEs". See pages 5- 7. X 1-20 3GPP TS 38.300 V15.0.0 (2017-12), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NR-RAN Overall Description; Stage 2 (Release 15) See pages 37-38Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family J7 Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From H04W 0076 / 27 01 / 01 / 2018 H04W 0076 / 10 01 / 01 / 2018

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