WO2019196000A1

WO2019196000A1 - Methods and system for carrying out small data fast path communication

Info

Publication number: WO2019196000A1
Application number: PCT/CN2018/082439
Authority: WO
Inventors: Fei Lu; Jinguo Zhu
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2018-04-10
Filing date: 2018-04-10
Publication date: 2019-10-17
Anticipated expiration: 2020-10-10
Also published as: CN111869310A

Abstract

A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network involves the second radio access network: receiving small data fast path parameters and a connection resume identifier from the wireless communication device during a radio resource control connection establishment procedure; deriving the first radio access network from the resume identifier; transmitting, to the first radio access network, a connection request including the small data fast path parameters and a tunnel endpoint identifier for small data fast path downlink data; and receiving, from the first radio access network, a tunnel endpoint identifier for small data fast path uplink data.

Description

METHODS AND SYSTEM FOR CARRYING OUT SMALL DATA FAST PATH COMMUNICATION

TECHNICAL FIELD

The present disclosure is related generally to wireless networks and, more particularly, to methods and systems for establishing a fast path for small data transmission.

BACKGROUND

In many current wireless networks, particularly those having devices that communication using infrequent, small data transmissions, various techniques have been developed for allowing small, fast data transmissions to be sent efficiently. In the context of large wireless networks (such as fifth generation networks) , if a wireless device using such transmissions moves to a different radio access network, the new radio access network cannot connect to the user plane function (i.e., the radio access network is not in the serving area of the user plane function) .

DRAWINGS

While the appended claims set forth the features of the present techniques with particularity, these techniques, together with their objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawings of which:

FIG. 1 is a block diagram of a system in which various embodiments of the disclosure are implemented.

FIG. 2 shows an example hardware architecture of a communication device.

FIG. 3 is a block diagram of a network environment in which, according to various embodiments, the devices depicted in FIG. 1 and FIG. 2 may be deployed.

FIG. 4 is an example of how small data fast path communication is established using currently-existing techniques.

FIG. 5 and FIG. 6 are communication flow diagrams showing an example of a currently-existing procedure for establishing small data fast path communication in the context of the network environment of FIG. 3.

FIG. 7, FIG. 8, FIG. 9, and FIG. 10 are communication flow diagrams showing examples of procedures for establishing small data fast path communication in the context of the network environment of FIG. 3, according to different embodiments.

DESCRIPTION

In an embodiment, a method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network involves the second radio access network carrying out the following actions: receiving small data fast path parameters and a connection resume identifier from the wireless communication device during a radio resource control connection establishment procedure; deriving the first radio access network from the resume identifier; transmitting, to the first radio access network, a connection request including the small data fast path parameters and a tunnel endpoint identifier for small data fast path downlink data; and receiving, from the first radio access network, a tunnel endpoint identifier for small data fast path uplink data.

According to another embodiment, a method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network involves the second radio access network carrying out the following actions: receiving small data fast path parameters and a connection resume identifier from the wireless communication device during a radio resource control connection establishment procedure; deriving the first radio access network from the resume identifier; receiving small data fast path uplink data from the wireless communication device; and transmitting the small data fast path uplink data to the first radio access network.

According to yet another embodiment, a method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network involves the second radio access network carrying out the following actions: receiving small data fast path parameters from the wireless communication device during a radio resource control connection establishment procedure; identifying a user plane function based on the small data fast path parameters; transmitting, to the user plane function, a request for the establishment of a tunnel for a small data fast path connection, wherein the request includes the small data fast path parameters and a tunnel endpoint identifier for small data fast path downlink data; and receiving, from the user plane function, a tunnel establishment response message that includes a tunnel endpoint identifier for the user plane function to be used for small data fast path uplink data.

According to still another embodiment, a method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network involves the second radio access network carrying out the following actions: receiving small data fast path parameters from the wireless communication device during a radio resource control connection establishment procedure; identifying a first user plane function based on the small data fast path parameters; receiving small data fast path uplink data from the wireless communication device; transmitting the small data fast path uplink data, the small data fast path parameters, and a tunnel endpoint identifier for downlink data to the first user plane function. The method also involves the first user plane function deriving the second user plane function from the small data fast path parameters; and transmitting the small data fast path uplink data, the small data fast path parameters, and downlink tunnel information for a small data fast path session to the second user plane function.

FIG. 1 depicts a communication system 100 in which the various embodiments described herein may be implemented. The communication system 100 includes several wireless communication devices ( “wireless communication device” will sometimes be shortened herein to “communication device” or “device” for convenient reference) . The communication devices depicted are a first communication device 102 (depicted as a user equipment ( “UE” ) ) , a second communication device 104 (depicted as a base station) , and a third communication device 106 (depicted as a UE) . It is to be understood that there may be many other communication devices and that the ones represented in FIG. 1 are meant only for the sake of example. In an embodiment, the wireless communication system 100 has many other components that are not depicted in FIG. 1, including other base stations, other UEs, wireless infrastructure, wired infrastructure, and other devices commonly found in wireless networks. Possible implementations of the communication devices include any device capable of wireless communication, such as a smartphone, tablet, laptop computer, and non-traditional devices (e.g., household appliances or other parts of the “Internet of Things” ) . When operating as part of a wireless communication system (e.g., part of a radio access network) , a wireless communication device may be referred to as a “wireless network node. ” A wireless communication device communicates primarily by transmitting and receiving wireless signals.

The second communication device 104 operates as a node of a RAN (such as a “Node B” of a fourth generation or fifth generation RAN) 108. The RAN 108 is communicatively linked to a CN 110. The CN 110 carries are many functions in support of the RAN 108 and has many components.

The following description will sometimes refer to a node and a UE without specific reference to FIG. 1. It is to be understood, however, that all of the methods described herein may be carried out by the communication devices of FIG. 1, and that references to a node, base station, and UE in a general manner are merely for convenience. Also, for each of the procedures described, in an embodiment, the steps are carried out in the order that the language sets forth. In other embodiments, the steps are carried out in different orders.

FIG. 2 illustrates a basic hardware architecture implemented by each of the wireless communication devices of FIG. 1, according to an embodiment. The elements of FIG. 1 may have other components as well. The hardware architecture depicted in FIG. 2 includes logic circuitry 202, memory 204, transceiver 206, and one or more antennas represented by antenna 208 (including transmit antennas and/or receive antennas) . The memory 204 may be or include a buffer that, for example, holds incoming transmissions until the logic circuitry is able to process the transmission. Each of these elements is communicatively linked to one another via one or more data pathways 210. Examples of data pathways include wires, conductive pathways on a microchip, and wireless connections. The hardware architecture of FIG. 2 may also be referred to herein as a “computing device. ”

The term “logic circuitry” as used herein means a circuit (a type of electronic hardware) designed to perform complex functions defined in terms of mathematical logic. Examples of logic circuitry include a microprocessor, a controller, or an application-specific integrated circuit. When the present disclosure refers to a device carrying out an action, it is to be understood that this can also mean that logic circuitry integrated with the device is, in fact, carrying out the action.

Turning to FIG. 3, a network environment in which, according to various embodiments, the devices depicted in FIG. 1 and FIG. 2 may be deployed will now be described. The network environment includes the RAN 108, the wireless communication device 102, and the CN 110. The network environment further includes a data network ( “DN” ) 302.

Continuing with FIG. 3, the CN 110 includes a unified data management server ( “UDM” ) 304, an access and mobility management function ( “AMF” ) 306, a session management function ( “SMF” ) 308, and a user plane function ( “UPF” ) 310.

In an embodiment, the AMF 306 provides the following services: registration management, connection management, reachability management, and mobility management. The AMF also carries out access authentication and access authorization. The AMF 306 acts as the non-access stratum ( “NAS” ) security termination and relays the session management ( “SM” ) NAS between a UE and an SMF.

According to an embodiment, the SMF 308 provides the following services: session Management (e.g., session establishment, modify and release) , UE internet protocol ( “IP” ) address allocation and management (including optional authorization) , selection and control of user plane ( “UP” ) functions, and downlink ( “DL” ) data notification.

In an embodiment, the UPF 310 provides the following services: serving an anchor point for Intra-/Inter-radio access technology ( “RAT” ) mobility, packet routing and forwarding, traffic usage reporting, quality of service ( “QoS” ) handling for the user plane, DL packet buffering, and DL data notification triggering.

It is to be understood that, although the devices of FIG. 3 have names that end in “function” or “entity, ” they are, in fact, computing devices that carry out functions (e.g., under the control of software) . Thus, for example, the UPF 310 is a computing device (or multiple computing devices working in concert) that carries out functions described herein.

The various devices in FIG. 3 communicate with one another in various ways, including the well-known interfaces shown with the lines labeled ‘Nx’ . Also, each of the devices depicted in FIG. 3 are meant to be representative. For example, there may be many SMFs and UPFs in the CN 110, and there may be multiple RANs, which the device 102 may encounter when in moves from location to location.

In one embodiment, “small data” refers to a block of data that is less than 200 bytes in size. Furthermore, according to an embodiment, “fast path” refers to a data transmission technique in which certain intermediate steps are skipped as compared to regular data transmissions. For example, a regular data transmission procedure may involve a device (e.g., a UE) first sending a service request message to an AMF and requesting the network (e.g., RAN) to set up the user plane for the data transmission.

Turning to FIG. 4, an example of how small data fast path ( “SDFP” ) communication is established using currently-existing techniques will now be described. The SDFP is established by providing the relevant UPF (UPF 310 in this example) or protocol data unit ( “PDU” ) session related information to the wireless communication device (device 102 in this example) from the SMF, which the wireless communication device would later provide to the RAN (RAN 108 in this example) . The UPF or PDU session relevant information allows the RAN to derive the path (e.g., over interface N3) to the UPF. At uplink ( “UL” ) data arrival, the wireless communication device passes the data, together with the UPF or PDU session relevant information, to the RAN. The RAN forwards the data (e.g., on the N3 interface) . Since all info required to forward the data is received from the wireless communication device, the RAN does not need to signal to the AMF or have any context information regarding the wireless communication device (e.g., UE context) stored.

Turning to FIG. 5, an example of a currently-existing procedure for establishing SDFP communication will now be described in the context of the network environment of FIG. 3. At 501, the device 102 sends an UL NAS TRANSPORT message to the AMF 306. This message includes single network slice selection assistance information ( “S-NSSAI” ) , data network name ( “DNN” ) , PDU session identifier ( “ID” ) , request type, and an N1 SM container (PDU Session Establishment Request) . The request type indicates “initial request” if the PDU Session Establishment is a request to establish a new PDU Session. The device 102 should provide an indication that it wants to establish a SDFP PDU session in the UL NAS TRANSPORT message.

At 502, the AMF 306 selects an SMF that supports the SDFP (SMF 308 in this example) . The AMF 306 also generates a SDFP security context. The AMF 306 sends Nsmf_PDUSession_CreateSMContext Request (which includes a subscriber permanent identifier ( “SUPI” ) , DNN, S-NSSAI, PDU Session ID, AMF ID, request type, N1 SM container (PDU Session Establishment Request) , user location information, access type, and an SDFP indication) to the SMF 308.

At 503, the SMF 308 responds with the Nsmf_PDUSession_CreateSMContext Response (SMF context Identifier) message.

At 504, the SMF 308 selects a UPF that supports the SDFP (UPF 310 in this example) . The SMF 308 sends the N4 Session Establishment request message to the UPF 310 and provides packet detection, enforcement and reporting rules to be installed on the UPF 310 for this PDU Session. If CN Tunnel Info is allocated by the SMF 308, the CN Tunnel Info is provided to the UPF 310 in this step. Also during this step, the SMF 308 will set up the SDFP security context in the UPF 310.

At 505, the UPF 310 acknowledges that by sending an N4 Session Establishment/Modification Response. If CN Tunnel Info is allocated by the UPF 310, the CN Tunnel Info is provided to the SMF 308 in this step.

At 506, the SMF 308 transmits to the AMF 306: Namf_Communication_N1N2MessageTransfer (including PDU Session ID, access type, N2 SM information (PDU Session ID, QoS flow identifier (s) ( “QFI (s) ” ) , QoS profile (s) , CN Tunnel Info, S-NSSAI, Session-aggregate maximum bit-rate ( “AMBR” ) , PDU Session Type) , N1 SM container (PDU Session Establishment Accept (QoS Rule (s) , S-NSSAI, allocated IP address, Session-AMBR, and selected PDU Session Type) ) ) . The PDU session establishment accept will also include the UPF information for this PDU session.

At 507, the AMF 306 responds with the Namf_Communication_N1N2MessageTransfer ACK.

At 508, the AMF 306 transmits to the RAN 108: N2 PDU Session Request (N2 SM information, NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) ) . The AMF 306 sends the NAS message containing a PDU Session ID and PDU Session Establishment Accept targeted to the device 102 and the N2 SM information received from the SMF 308 within the N2 PDU Session Request to the RAN 108.

At 509, the RAN 108 and device 102 engage in access network ( “AN” ) specific signaling exchange that is related to the information received from SMF. The RAN 108 also allocates RAN N3 tunnel information ( “Info” ) for the PDU Session. The AN Tunnel Info includes a tunnel endpoint for the involved RAN node. Also, the RAN 108 forwards the NAS message (PDU Session ID, N1 SM container (PDU Session Establishment Accept) ) provided in step 508 to the device 102. The RAN 108 only provides the NAS message to the device 102 if the necessary RAN resources are established and the allocation of RAN tunnel information is successful.

At 510, the RAN 108 transmits to the AMF 306: N2 PDU Session Response (PDU Session ID, Cause, N2 SM information (PDU Session ID, AN Tunnel Info, List of accepted/rejected QFI (s) ) ) . The AN Tunnel Info corresponds to the access network address of the N3 tunnel corresponding to the PDU Session.

At 511, the AMF 306 transmits to the SMF 308: Nsmf_PDUSession_UpdateSMContext Request (N2 SM information, Request Type) . In this step, the AMF 306 forwards the N2 SM information received from RAN to the SMF 308. If the list of rejected QFI (s) is included in N2 SM information, the SMF 308 releases the rejected QFI (s) associated QoS profiles.

At 512, the SMF 308 initiates an N4 Session Modification procedure with the UPF 310. The SMF 308 provides AN Tunnel Info to the UPF 310 as well as the corresponding forwarding rules.

At 513, the UPF 310 provides an N4 Session Modification Response to the SMF 308.

At 514, the SMF 308 transmits to the AMF 306: Nsmf_PDUSession_UpdateSMContext Response (Cause) .

Turning to FIG. 6, an example of a currently-existing procedure for establishing SDFP communication will now be described in the context of the network environment of FIG. 3.

At 601, the device 102 establishes a radio resource control ( “RRC” ) connection for SDFP transfer. In doing so, the device 102 passes parameters for selection of a UPF for the PDU Session for the device 102 to the RAN 108.

At 602, the device 102 encrypts and integrity protects an UL data PDU and passes it to the RAN 108.

At 603, the RAN 108 forwards the UL data PDU to the selected UPF (UPF 310 in this case) . The RAN 108 selects the UPF based on the SDFP information provided by the device 102. The RAN 108 will also provide the UPF 310 with RAN N3 DL Tunnel Info for the SDFP session.

At 604, the UPF 310 checks integrity protection and decrypts the UL data PDU. If the check is passed, the UPF 310 forwards the UL data on the N6/N9 interface. In addition, the UPF 310 enables subsequent DL data transmissions to the RAN node it received the UP data PDU from.

An issue that arises with the aforementioned setup occurs when the wireless communication device moves to a new RAN in a fifth generation mobility management ( “MM” ) IDLE state. In that case, the device may have UL data to be sent, but the new RAN cannot connect to the UPF as shown in FIG. 5 and FIG. 6. This would trigger the RAN, AMF and SMF to select a new UPF. However, doing so would trigger a lot of control plane signalling.

In an embodiment, a method for carrying out small data fast path communication addresses these issues with the following procedure: When the wireless communication device (e.g., UE) moves from a first RAN to a second RAN, (1) The wireless communication device connects to the second RAN. (2) (a) This second RAN will establish the Xn connectivity for the SDFP with the first RAN and the first RAN will send the small data to the UPF; or (2) (b) the second RAN will connect to a new UPF (second UPF) and this new UPF will send the small data to the old UPF (first UPF) .

Turning to FIG. 7, a procedure carried for carrying out SDFP communication according to an embodiment will now be described in the context of the network environment of FIG. 3. In this example, it may be assumed that, when the device 102 had connected to the first RAN 108a, it carried out many of the procedures of FIG. 5, including step 509, and that the RAN 108a had given the device 102 a resume ID.

At 701, the wireless communication device establishes an RRC for SDFP transfer. In doing so, the device 102 passes parameters for selection of a UPF for the PDU Session for the device 102 to the second RAN 108b. The second RAN 108b cannot connect to the UPF, although it can derive the UPF address. The device 102 includes the resume ID in its communication to the second RAN 108b. Then, the device 102 derives the first RAN using the resume ID. It is to be noted that, in some implementations, the SDFP information includes an identifier of the first RAN. In such implementations, the first RAN can be derived from the SDFP information. If this method is used, then when the device 102 sends an UL NAS TRANSPORT message to the AMF 306 in step 501, the first RAN 108a will include its RAN ID in the message that it passes to the AMF 306, which the AMF 306 will forward to the SMF 308 in step 502. The SMF 308 will combine the RAN ID with the SDFP information that is sent to the device 102 as defined in the step 506 in the N1 SM container (PDU Session Establishment Accept) .

At 702, the second RAN 108 transmits a request to the first RAN 108a to establish Xn connectivity to the first RAN 108a. The second RAN 108b may use the resume ID and the SDFP information (or use just the SDFP information if it contains the RAN ID) to derive the first RAN 108a (e.g., determine the identity, etc. of the first RAN 108a) . In the request message, the second RAN 108b also includes the SDFP information and the tunnel endpoint identifier ( “TEID” ) for SDFP DL data.

At 703, the first RAN 108a responds with an Xn connectivity response. In the message, the first RAN 108a includes the old RAN TEID for SDFP UL data.

At 704. The device 102 encrypts and integrity protects an UL data PDU and transmits it to the second RAN 108b.

At 705, the second RAN 108b forwards the UL data PDU to the derived first RAN 108a.

At 706, the first RAN 108a forwards the UL data PDU to the selected UPF (UPF 310 in this example) . The first RAN 108a selects the UPF based on the SDFP information provided by the device 102. The first RAN 108a will also provide the UPF 310 with RAN N3 DL Tunnel Info for the SDFP session.

At 707, the UPF 310 checks integrity protection and decrypts the UL data PDU. If the check is passed, the UPF 310 forwards the UL data on the N6 interface. In addition, the UPF 310 enables subsequent DL data transmissions to the RAN node it received the UL data PDU from.

Turning to FIG. 8, a procedure carried for carrying out SDFP communication according to another embodiment will now be described in the context of the network environment of FIG. 3. As in the previous example, it may be assumed that, when the device 102 had connected to the first RAN 108a, it carried out many of the procedures of FIG. 5, including step 509, and that the RAN 108a had given the device 102 a resume ID.

At 801, the device 102 establishes an RRC for SDFP transfer. Parameters for selection of the UPF for the PDU Session for the device are passed to the second RAN 108b. The device 102 provides the resume ID to the second RAN 108b. Then, the device 102 derives the first RAN 108a using the resume ID.

At 802, the device 102 encrypts, and integrity protects an UL data PDU and passes it to the second RAN 108b. The second RAN 108b cannot connect to the UPF, although it can derive the UPF address. The device 102 includes the resume ID in its communication to the second RAN 108b. Then, the device 102 derives the first RAN using the resume ID.

At 803, the second RAN 108b derives the information of the first RAN 108a based on the SDFP information and forwards the UL data PDU to the first RAN 108a. In the data, the second RAN 108b also provides the first RAN 108a with Xn DL Tunnel Info for the SDFP session.

At 804, the first RAN 108a forwards the UL data PDU to the selected UPF (UPF 310 in this example) . The first RAN 108a selects the UPF based on the SDFP information provided by the device 102. The first RAN 108a will also provide the UPF 310 with RAN N3 DL Tunnel Info for the SDFP session.

At 805, the UPF 310 checks integrity protection and decrypts the UL data PDU. If the check is passed, the UPF 310 forwards the UL data on the N6 interface. In addition, the UPF 310 enables subsequent DL data transmissions to the RAN node it received the UP data PDU from.

Turning to FIG. 9, a procedure carried for carrying out SDFP communication according to yet another embodiment will now be described in the context of the network environment of FIG. 3, with the following addition: there is an initial UPF (first UPF 310a) and a new UPF (second UPF 310b) .

At 901, the device 102 establishes an RRC for SDFP transfer. Parameters for selection of a UPF for the PDU Session for the device 102 are passed to the second RAN 108b. The RAN 108 cannot connect to the UPF, although it can derive the UPF address.

At 902, the RAN 108 selects a UPF (UPF 310b in this example) and requests to establish an N3 Tunnel with the UPF. The RAN 108 may derive the second UPF 310b based on the SDFP information. In some embodiments, this UPF can also be a default UPF configured at the RAN 108 for SDFP transmissions) . In the request message to the second UPF 310b, the RAN 108 also includes the SDFP information and the RAN TEID for SDFP DL data.

At 903, the second UPF 310b responds with the N4 tunnel establishment response. In the message, the second UPF 310b includes its UPF TEID for SDFP UL data.

At 904, the second UPF 310b requests to establish an N9 Tunnel with the first UPF 310a. The second UPF 310b may use the SDFP information to derive the first UPF 310a. In the request message, the second UPF 310b also includes the SDFP information and the N9 UPF TEID for SDFP DL data.

At 905, the first UPF 310a responds with an N9 tunnel establishment response. In the message, the first UPF 310a includes the new UPF TEID for SDFP UL data.

At 906, the device 102 encrypts and integrity protects an UL data PDU and passes it to the RAN 108.

At 907, the RAN 108 forwards the UL data PDU to the derived new UPF (UPF 310b in this example) .

At 908, the second UPF 310b forwards the UL data PDU to the old UPF (first UPF 310a) . The second UPF 310b selects the first UPF based on the SDFP information provided by the device 102. The second UPF 310b will also provide the first UPF 310a with UPF N9 DL Tunnel Info for the SDFP session.

At 909, the first UPF 310a checks integrity protection and decrypts the UL data PDU. If the check is passed, the first UPF 310a forwards the UL data on the N6 interface. In addition, the first UPF 310a enables subsequent DL data transmissions to the RAN node it received the UP data PDU from.

Turning to FIG. 10, an example of how a wireless communication device establishes an RRC connection for SDFP transfer in accordance with an embodiment will now be described. The steps shown in FIG. 10 are depicted in the context of the networking environment of FIG. 3, with the following addition: there is an initial UPF (first UPF 310a) and a new UPF (second UPF 310b) . Parameters for selection of UPF for the PDU Session for the UE are passed to the RAN.

At the start, the RAN 108 cannot connect to the UPF, although it can derive the UPF address. At 1002, the device 102 encrypts and integrity protects an UL data PDU and passes it to RAN 108.

At 1003, the RAN 108 forwards the UL data PDU to the derived new UPF (the second UPF 310b) . In the message to the second UPF 310, the RAN will include the RAN N3 TEID for DL data. The RAN 108 derives the UPF based on the SDFP information provided by the device 102.

At 1004, the second UPF 310b forwards the UL data PDU to the old UPF (first UPF 310a) . The second UPF 310b derives the first UPF 310a based on the SDFP information provided by the device 1002. The second UPF 310b will also provide the first UPF 310a with UPF N9 DL Tunnel Info for the SDFP session.

At 1005, the first UPF 310a checks integrity protection and decrypts the UL data PDU. If the check is passed, the first UPF 310a forwards the UL data on the N6 interface. In addition, the first UPF 310a enables subsequent DL data transmissions to the RAN node it received the UP data PDU from.

Any and all of the methods described herein are carried out by or on one or more computing devices. Furthermore, instructions for carrying out any or all of the methods described herein may be stored on a non-transitory, computer-readable medium, such as any of the various types of memory described herein.

It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from their spirit and scope of as defined by the following claims. For example, the steps of the various methods can be reordered in ways that will be apparent to those of skill in the art.

Claims

A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network, the method comprising:

the second radio access network

receiving small data fast path parameters and a connection resume identifier from the wireless communication device during a radio resource control connection establishment procedure;

deriving the first radio access network from the resume identifier;

transmitting, to the first radio access network, a connection request including the small data fast path parameters and a tunnel endpoint identifier for small data fast path downlink data; and

receiving, from the first radio access network, a tunnel endpoint identifier for small data fast path uplink data.
The method of claim 1, further comprising receiving small data fast path uplink data from the wireless communication device.
The method of claim 2, further comprising transmitting the small data fast path uplink data to the first radio access network using the tunnel endpoint identifier received from the first radio access network.
The method of claim 2, further comprising the first radio access network:

selecting a user plane function based on the small data fast path parameters; and

transmitting, to the selected user plane function, downlink tunnel information for a small data fast path session.
The method of claim 4, further comprising the user plane function:

checking integrity protection on the small data fast path uplink data;

decrypting the small data fast path uplink data; and

forwarding the small data fast path uplink data.
A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network, the method comprising:

the second radio access network

receiving small data fast path parameters and a connection resume identifier from the wireless communication device during a radio resource control connection establishment procedure;

deriving the first radio access network from the resume identifier;

receiving small data fast path uplink data from the wireless communication device; and

transmitting the small data fast path uplink data to the first radio access network.
The method of claim 6, further comprising the first radio access network:

selecting a user plane function based on the small data fast path parameters; and

transmitting, to the selected user plane function, downlink tunnel information for a small data fast path session.
The method of claim 7, further comprising the user plane function:

checking integrity protection on the small data fast path uplink data;

decrypting the small data fast path uplink data; and

forwarding the small data fast path uplink data.
A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network, the method comprising:

the second radio access network

receiving small data fast path parameters from the wireless communication device during a radio resource control connection establishment procedure;

identifying a user plane function based on the small data fast path parameters;

transmitting, to the user plane function, a request for the establishment of a tunnel for a small data fast path connection, wherein the request includes the small data fast path parameters and a tunnel endpoint identifier for small data fast path downlink data; and

receiving, from the user plane function, a tunnel establishment response message that includes a tunnel endpoint identifier for the user plane function to be used for small data fast path uplink data.
The method of claim 9, wherein the user plane function is a first user plane function, the method further comprising the first user plane function transmitting, to a second user plane function, a request for the establishment of a tunnel for small data fast path data downlink.
The method of claim 10, further comprising the first user plane function deriving the second user plane function from the small data fast path parameters.
The method of claim 10, wherein the tunnel establishment request includes the small data fast path parameters and a tunnel endpoint identifier for downlink data.
The method of claim 10, further comprising the first user plane function receiving, from the second user plane function, a tunnel establishment response message that includes a tunnel endpoint identifier for small data fast path uplink data.
The method of claim 9, further comprising the second radio access network:

receiving uplink data from the wireless communication device; and

forwarding the received uplink data to the user plane function.
The method of claim 14, further comprising the first user plane function transmitting the uplink data to the second user plane function.
The method of claim 15, further comprising the second user plane function:

checking integrity protection on the small data fast path uplink data;

decrypting the small data fast path uplink data; and

forwarding the small data fast path uplink data.
A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network, the method comprising:

the second radio access network

receiving small data fast path parameters from the wireless communication device during a radio resource control connection establishment procedure;

identifying a first user plane function based on the small data fast path parameters;

receiving small data fast path uplink data from the wireless communication device;

transmitting the small data fast path uplink data, the small data fast path parameters, and a tunnel endpoint identifier for downlink data to the first user plane function;

the first user plane function

deriving the second user plane function from the small data fast path parameters;

transmitting the small data fast path uplink data, the small data fast path parameters, and downlink tunnel information for a small data fast path session to the second user plane function.
The method of claim 17, further comprising the second user plane function:

checking integrity protection on the small data fast path uplink data;

decrypting the small data fast path uplink data; and

forwarding the small data fast path uplink data.
A method for carrying out small data fast path communication for a wireless communication device moving from a first radio access network to a second radio access network, the method comprising:

the second radio access network

receiving small data fast path information from the wireless communication device during a protocol data unit session establishment procedure;

deriving the first radio access network from the small data fast path information;

transmitting, to the first radio access network, a connection request including the small data fast path information and a tunnel endpoint identifier for small data fast path downlink data; and

receiving, from the first radio access network, a tunnel endpoint identifier for small data fast path uplink data.
The method of claim 19, further comprising receiving small data fast path uplink data from the wireless communication device.
The method of claim 20, further comprising transmitting the small data fast path uplink data to the first radio access network using the tunnel endpoint identifier received from the first radio access network.
The method of claim 20, further comprising the first radio access network:

selecting a user plane function based on the small data fast path information; and

transmitting, to the selected user plane function, downlink tunnel information for a small data fast path session.
The method of claim 22, further comprising the user plane function:

checking integrity protection on the small data fast path uplink data;

decrypting the small data fast path uplink data; and

forwarding the small data fast path uplink data.
A system configured to carry out the method of any one of claims 1 through 23.
A non-transitory computer-readable medium having stored thereon computer-executable instructions for carrying out the method of any one of claims 1 through 23.