Internet protocol multimedia subsystem signaling during fallback to legacy cell

Abstract

Various aspects of the disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) can receive an Internet Protocol Multimedia Subsystem (IMS) configuration message from a New Radio (NR) cell. The UE can receive an instruction from the NR cell to fallback to a legacy cell. The UE can store a response to the IMS configuration message based at least in part on receiving the instruction to fallback. The UE can transmit the response to the IMS configuration message to the legacy cell prior to transmitting another IMS message. Numerous other aspects are described.

Description

Technical Field

[0001] In summary, various aspects of this disclosure relate to wireless communications, and particularly to technologies and apparatus for Internet Protocol Multimedia Subsystem signaling during fallback to a legacy cell. Background Technology

[0002] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / Improved LTE is an enhanced set of the Universal Mobile Telecommunications System (UMTS) mobile standard released by the 3rd Generation Partnership Project (3GPP).

[0003] A wireless network may include multiple base stations (BSs) capable of supporting communication for multiple user equipments (UEs). UEs can communicate with base stations (BSs) via downlinks and uplinks. A downlink (or forward link) refers to the communication link from the BS to the UE, and an uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, gNB, Access Point (AP), Radio Headend, Transmit / Receive Point (TRP), New Radio (NR) BS, 5G Node B, etc.

[0004] The above multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different user equipment to communicate at the city, country, region, and even global levels. New Radio (NR) (also known as 5G) is an enhancement set of the LTE mobile standard released by the 3rd Generation Partnership Project (3GPP). NR is designed to better integrate with other open standards by improving spectrum efficiency, reducing costs, improving service, utilizing new spectrum, and using Orthogonal Frequency Division Multiplexing (OFDM) with Cyclic Prefix (CP) (CP-OFDM) on the downlink (DL) and CP-OFDM and / or SC-FDM (e.g., also known as Discrete Fourier Transform Spread Spectrum OFDM (DFT-s-OFDM)) on the uplink (UL), thereby better supporting mobile broadband internet access, as well as beamforming, multiple-input multiple-output (MIMO) antenna technologies, and carrier aggregation. As the demand for mobile broadband access continues to grow, further improvements to LTE, NR, and other radio access technologies remain useful. Summary of the Invention

[0005] A user equipment (UE) for wireless communication includes: a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors being configured to: receive an Internet Protocol Multimedia Subsystem (IMS) configuration message from a New Radio (NR) cell; receive an instruction from the NR cell for falling back to a legacy cell; store a response to the IMS configuration message based at least in part on receiving the instruction for falling back; and send the response to the IMS configuration message to the legacy cell before sending another IMS message.

[0006] In some aspects, a base station for wireless communication includes: a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors being configured to: receive a connection request from a UE, wherein the connection request is at least partially based on an instruction for fallback from an NR cell; and receive from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message.

[0007] In some aspects, a method of wireless communication performed by a UE includes: receiving an IMS configuration message from an NR cell; receiving an instruction from the NR cell for falling back to a legacy cell; storing a response to the IMS configuration message based at least in part on receiving the instruction for falling back; and sending the response to the IMS configuration message to the legacy cell before sending another IMS message.

[0008] In some aspects, a method of wireless communication performed by a base station includes: receiving a connection request from a UE, wherein the connection request is at least partially based on an instruction for fallback from an NR cell; and receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message.

[0009] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to: receive an IMS configuration message from an NR cell; receive instructions from the NR cell for falling back to a legacy cell; store a response to the IMS configuration message based at least in part on receiving the instructions for falling back; and send the response to the IMS configuration message to the legacy cell before sending another IMS message.

[0010] In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a base station, cause the base station to: receive a connection request from a UE, wherein the connection request is at least in part based on instructions for fallback from an NR cell; and receive a response from the UE to an IMS configuration message sent by the NR cell before receiving another IMS message.

[0011] In some aspects, an apparatus for wireless communication includes: a unit for receiving an IMS configuration message from an NR cell; a unit for receiving an instruction for falling back to a legacy cell from the NR cell; a unit for storing a response to the IMS configuration message based at least in part on receiving the instruction for falling back; and a unit for sending the response to the IMS configuration message to the legacy cell before sending another IMS message.

[0012] In some aspects, an apparatus for wireless communication includes: a unit for receiving a request for connection from a UE, wherein the request for connection is at least partially based on an instruction for fallback from an NR cell; and a unit for receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message.

[0013] In general, the aspects include methods, apparatus, systems, computer program products, non-transitory computer-readable media, user equipment, base stations, wireless communication equipment and / or processing systems as fully described herein with reference to the accompanying drawings and description and as shown by the accompanying drawings and description.

[0014] The foregoing has provided a fairly broad overview of the features and technical advantages of examples according to this disclosure in order to better understand the following detailed description. Additional features and advantages will be described below. The disclosed concepts and specific examples can be readily used as the basis for modifying or designing other structures for achieving the same purpose as this disclosure. Such equivalent constructions do not depart from the scope of the appended claims. The characteristics of the concepts disclosed herein (both their organization and manner of operation) and their associated advantages will be better understood when considered in conjunction with the accompanying drawings, based on the following description. Each drawing in the accompanying drawings is provided for illustrative and descriptive purposes and is not intended to define a limitation of the claims. Attached Figure Description

[0015] To gain a full understanding of the foregoing features of this disclosure, a more specific description of the invention, briefly summarized above, can be obtained by referring to various aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only certain typical aspects of this disclosure and are therefore not intended to limit the scope of the disclosure, as other equally valid aspects are permissible under this description. The same reference numerals in different drawings may identify the same or similar elements.

[0016] Figure 1 This is a diagram illustrating examples of wireless networks according to various aspects of this disclosure.

[0017] Figure 2 This is a diagram illustrating an example of communication between a base station and a UE in a wireless network according to various aspects of this disclosure.

[0018] Figure 3 This is a diagram illustrating an example of a voice call failure during an Evolved Packet System (EPS) fallback, according to various aspects of this disclosure.

[0019] Figure 4 This is a diagram illustrating examples of Internet Protocol (IP) Multimedia Subsystem (IMS) signaling associated with various aspects of this disclosure during fallback to a traditional cell.

[0020] Figure 5-6 This is a diagram illustrating an example process associated with IMS signaling during fallback to a legacy cell, according to various aspects of this disclosure.

[0021] Figure 7-8 This is a block diagram of an example device for wireless communication according to various aspects of this disclosure. Detailed Implementation

[0022] The various aspects of this disclosure are described more fully below with reference to the accompanying drawings. However, this disclosure may be embodied in many different forms and should not be construed as limited to any particular structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art will understand that the scope of this disclosure is intended to cover any aspect of this disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of this disclosure. For example, an apparatus or a method may be implemented using any number of the aspects set forth herein. Furthermore, the scope of this disclosure is intended to cover such apparatuses or methods implemented using structures, functions, or structures and functions other than or different from the aspects of this disclosure set forth herein. It should be understood that any aspect of this disclosure disclosed herein may be embodied by one or more elements of the claims.

[0023] Several aspects of a telecommunications system will now be described with reference to various devices and techniques. These devices and techniques will be described in detail below and illustrated in the accompanying drawings, through various frames, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be implemented using hardware, software, or a combination thereof. Whether such an element is implemented as hardware or software depends on the specific application and the design constraints imposed on the entire system.

[0024] It should be noted that while this document may use terms commonly associated with 5G or NR radio access technology (RAT) to describe aspects, aspects of this disclosure may be applied to other RATs, such as 3G RAT, 4G RAT and / or RATs after 5G (e.g., 6G).

[0025] Figure 1This is a diagram illustrating an example of a wireless network 100 according to various aspects of this disclosure. Wireless network 100 may be or may include elements of a 5G (NR) network and / or an LTE network, as well as other examples. Wireless network 100 may include multiple base stations 110 (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A base station (BS) is an entity that communicates with a user equipment (UE) and may also be referred to as an NR BS, Node B, gNB, 5G Node B (NB), access point, Transmit / Receive Point (TRP), etc. Each BS can provide communication coverage for a specific geographic area. In 3GPP, the term "cell" may refer to the coverage area of ​​a BS and / or the BS subsystem serving that coverage area, depending on the context in which the term is used.

[0026] A BS can provide communication coverage for macrocells, picocells, femtocells, and / or another type of cell. A macrocell can cover a relatively large geographic area (e.g., a radius of several kilometers) and can allow unrestricted access by UEs with service subscriptions. A picocell can cover a relatively small geographic area and can allow unrestricted access by UEs with service subscriptions. A femtocell can cover a relatively small geographic area (e.g., a residential area) and can allow restricted access by UEs associated with that femtocell (e.g., UEs in a Closed User Group (CSG)). A BS used for macrocells can be referred to as a macro BS. A BS used for picocells can be referred to as a pico BS. A BS used for femtocells can be referred to as a femtocell BS or a home BS. Figure 1 In the examples shown, BS 110a can be a macro BS for macro cell 102a, BS 110b can be a pico BS for pico cell 102b, and BS 110c can be a femto BS for femto cell 102c. A BS can support one or more (e.g., three) cells. The terms “eNB,” “base station,” “NR BS,” “gNB,” “TRP,” “AP,” “Node B,” “5G NB,” and “cell” are used interchangeably herein.

[0027] In some respects, the cell may not be stationary, and the geographical area of ​​the cell may move depending on the location of the mobile BS. In some respects, BSs may be interconnected with each other and / or with one or more other BSs or network nodes (not shown) in the wireless network 100 using any suitable transport network via various types of backhaul interfaces (such as direct physical connections or virtual networks).

[0028] The wireless network 100 may also include a relay station. A relay station is an entity that can receive data transmissions from an upstream station (e.g., a BS or a UE) and transmit the data transmissions to a downstream station (e.g., a UE or a BS). A relay station can also be a UE capable of relaying transmissions for other UEs. Figure 1 In the example shown, relay BS 110d can communicate with macro BS 110a and UE 120d to facilitate communication between BS 110a and UE 120d. A relay BS can also be referred to as a relay station, relay base station, repeater, etc.

[0029] Wireless network 100 can be a heterogeneous network comprising different types of Base Stations (BSs) such as macro BSs, pico BSs, femto BSs, relay BSs, etc. These different types of BSs can have different transmit power levels, different coverage areas, and different effects on interference in wireless network 100. For example, macro BSs can have high transmit power levels (e.g., 5 to 40 watts), while pico BSs, femto BSs, and relay BSs can have lower transmit power levels (e.g., 0.1 to 2 watts).

[0030] Network controller 130 can be coupled to a group of base stations (BSs) and can provide coordination and control for these BSs. Network controller 130 can communicate with the BSs via backhaul. BSs can also communicate with each other via wireless or wired backhaul (e.g., directly or indirectly).

[0031] UE 120 (e.g., 120a, 120b, 120c) may be distributed throughout the wireless network 100, and each UE may be stationary or mobile. UE may also be referred to as an access terminal, terminal, mobile station, user unit, station, etc. UE may be a cellular phone (e.g., a smartphone), personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop computer, cordless phone, wireless local loop (WLL) station, tablet device, camera, gaming device, netbook, smartbook, ultrabook, medical device or apparatus, biometric sensor / device, wearable device (smartwatch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet, etc.)), entertainment device (e.g., music or video device, or satellite radio unit, etc.), vehicle component or sensor, smart meter / sensor, industrial manufacturing equipment, GPS device, or any other suitable device configured to communicate via wireless or wired media.

[0032] Some UEs can be considered Machine-Type Communication (MTC) or Evolved or Enhanced Machine-Type Communication (eMTC) UEs. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, and / or location tags, which can communicate with a base station, another device (e.g., a remote device), or some other entity. Wireless nodes can provide connectivity to or to a network (e.g., a wide area network such as the Internet or cellular networks) via wired or wireless communication links, for example. Some UEs can be considered Internet of Things (IoT) devices, and / or can be implemented as NB-IoT (Narrowband Internet of Things) devices. Some UEs can be considered Customer Premises Equipment (CPE). UE 120 can be included within a housing housing the components of UE 120, such as processor components and / or memory components. In some aspects, the processor components and memory components can be coupled together. For example, the processor components (e.g., one or more processors) and memory components (e.g., memory) can be operatively coupled, communicatively coupled, electronically coupled, and / or electrically coupled.

[0033] Typically, any number of wireless networks can be deployed in a given geographical area. Each wireless network can support a specific RAT and can operate on one or more frequencies. A RAT can also be referred to as a radio technology, air interface, etc. A frequency can also be referred to as a carrier, channel, etc. Each frequency can support a single RAT in a given geographical area to avoid interference between wireless networks using different RATs. In some cases, NR or 5G RAT networks can be deployed.

[0034] In some respects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., without using base station 110 as an intermediary for communication with each other). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.) and / or mesh networks. In this case, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described herein as being performed by base station 110.

[0035] Devices in the wireless network 100 can communicate using the electromagnetic spectrum, which can be subdivided into various categories, bands, channels, etc., based on frequency or wavelength. For example, devices in the wireless network 100 can communicate using an operating band with a first frequency range (FR1) (spanning from 410 MHz to 7.125 GHz), and / or can communicate using an operating band with a second frequency range (FR2) (spanning from 24.25 GHz to 52.6 GHz). The frequencies between FR1 and FR2 are sometimes referred to as intermediate frequencies (IFs). Although a portion of FR1 is greater than 6 GHz, FR1 is generally referred to as the "below 6 GHz" band. Similarly, FR2 is generally referred to as the "millimeter wave" band, although it is different from the extremely high frequency (EHF) band (30 GHz–300 GHz) designated as the "millimeter wave" band by the International Telecommunication Union (ITU). Therefore, unless otherwise explicitly stated, it should be understood that the terms "below 6 GHz" and the like (if used herein) can broadly refer to frequencies below 6 GHz, frequencies within FR1, and / or intermediate frequencies (e.g., above 7.125 GHz). Similarly, unless otherwise explicitly stated, it should be understood that the terms "millimeter wave" and the like (if used herein) can broadly refer to frequencies within the EHF band, frequencies within FR2, and / or intermediate frequencies (e.g., below 24.25 GHz). It is anticipated that the frequencies included in FR1 and FR2 may be modified, and the techniques described herein are applicable to those modified frequency ranges.

[0036] As pointed out above, Figure 1 This is provided as an example. Other examples may differ from the one provided. Figure 1 The example described.

[0037] Figure 2 This is a diagram illustrating an example of communication between a base station 110 and a UE 120 in a wireless network 100 according to various aspects of this disclosure. The base station 110 may be equipped with T antennas 234a to 234t, and the UE 120 may be equipped with R antennas 252a to 252r, wherein generally, T ≥ 1 and R ≥ 1.

[0038] At base station 110, transmitting processor 220 can receive data for one or more UEs from data source 212, select one or more modulation and coding schemes (MCS) for each UE based at least in part on channel quality indicators (CQI) received from each UE, process (e.g., code and modulate) the data for each UE based at least in part on the MCS selected for each UE, and provide data symbols for all UEs. Transmitting processor 220 can also process system information (e.g., semi-static resource allocation information (SRPI)) and control information (e.g., CQI requests, permission, and / or upper-layer signaling), and provide overhead symbols and control symbols. Transmitting processor 220 can also generate reference symbols for reference signals (e.g., cell-specific reference signals (CRS) or demodulation reference signals (DMRS)) and synchronization signals (e.g., primary synchronization signal (PSS) or secondary synchronization signal (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 can perform spatial processing (e.g., precoding, if applicable) on data symbols, control symbols, overhead symbols, and / or reference symbols, and can provide T output symbol streams to T modulators (MODs) 232a to 232t. Each modulator 232 can (e.g., for OFDM) process its corresponding output symbol stream to obtain an output sample stream. Each modulator 232 can further process (e.g., convert to analog, amplify, filter, and up-convert) the output sample stream to obtain a downlink signal. The T downlink signals from modulators 232a to 232t can be transmitted via T antennas 234a to 234t respectively.

[0039] At UE 120, antennas 252a to 252r can receive downlink signals from base station 110 and / or other base stations, and can provide the received signals to demodulators (DEMODs) 254a to 254r respectively. Each demodulator 254 can adjust (e.g., filter, amplify, down-convert, and digitize) the received signal to obtain an input sample. Each demodulator 254 can further process the input sample (e.g., for OFDM) to obtain a received symbol. MIMO detector 256 can obtain the received symbols from all R demodulators 254a to 254r, perform MIMO detection on the received symbols (if applicable), and provide the detected symbols. Receive processor 258 can process (e.g., demodulate and decode) the detected symbols, provide decoded data for UE 120 to data sink 260, and provide decoded control information and system information to controller / processor 280. The term "controller / processor" can refer to one or more controllers, one or more processors, or a combination thereof. The channel processor can determine the Reference Signal Received Power (RSRP) parameter, the Received Signal Strength Indicator (RSSI) parameter, the Reference Signal Received Quality (RSRQ) parameter, and / or the Channel Quality Indicator (CQI) parameter, as well as other examples. In some aspects, one or more components of the UE 120 may be included in the housing 284.

[0040] Network controller 130 may include communication unit 294, controller / processor 290, and memory 292. Network controller 130 may include one or more devices, such as those in a core network. Network controller 130 may communicate with base station 110 via communication unit 294.

[0041] Antennas (e.g., antennas 234a to 234t and / or antennas 252a to 252r) may include or be included within the following: one or more antenna panels, antenna groups, antenna element sets, and / or antenna arrays, and other examples. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include one or more antenna elements. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include coplanar antenna element sets and / or non-coplanar antenna element sets. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include antenna elements within a single housing and / or multiple antenna elements within housings. Antenna panels, antenna groups, antenna element sets, and / or antenna arrays may include antenna elements coupled to one or more transmitting and / or receiving components (such as...) Figure 2 One or more antenna elements (one or more components).

[0042] On the uplink, at UE 120, the transmitting processor 264 can receive and process data from data source 262 and control information from controller / processor 280 (e.g., for reporting RSRP, RSSI, RSRQ, and / or CQI). The transmitting processor 264 can also generate reference symbols for one or more reference signals. Symbols from the transmitting processor 264 can be pre-coded (if applicable) by TX MIMO processor 266, further processed by modulators 254a to 254r (e.g., for DFT-s-OFDM or CP-OFDM), and transmitted to base station 110. In some aspects, the modulator and demodulator (e.g., MOD / DEMOD 254) of UE 120 can be included in the modem of UE 120. In some aspects, UE 120 includes a transceiver. The transceiver may include any combination of antenna 252, modulator and / or demodulator 254, MIMO detector 256, receive processor 258, transmit processor 264 and / or TX MIMO processor 266. The transceiver may be used by a processor (e.g., controller / processor 280) and memory 282 to perform aspects of any of the methods described herein (e.g., as referenced). Figure 4-6 (Described).

[0043] At base station 110, uplink signals from UE 120 and other UEs can be received by antenna 234, processed by demodulator 232, detected by MIMO detector 236 (if applicable), and further processed by receiver processor 238 to obtain decoded data and control information transmitted by UE 120. Receiver processor 238 can provide decoded data to data sink 239 and decoded control information to controller / processor 240. Base station 110 may include communication unit 244 and communicate with network controller 130 via communication unit 244. Base station 110 may include scheduler 246 to schedule UE 120 for downlink and / or uplink communication. In some aspects, modulators and demodulators (e.g., MOD / DEMOD 232) of base station 110 may be included in the modem of base station 110. In some aspects, base station 110 includes a transceiver. The transceiver may include any combination of antenna 234, modulator and / or demodulator 232, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver may be used by a processor (e.g., controller / processor 240) and memory 242 to perform aspects of any of the methods described herein (e.g., as referenced). Figure 4-6 (Described).

[0044] The controller / processor 240 of base station 110, the controller / processor 280 of UE 120 and / or Figure 2 Any other components may perform one or more techniques associated with IMS signaling during fallback to a legacy cell, as described in more detail elsewhere herein. For example, the controller / processor 240 of base station 110, the controller / processor 280 of UE 120, and / or Figure 2 Any other component can perform or direct, for example Figure 5 Process 500 Figure 6 The operation of process 600 and / or other processes as described herein. Memory 242 and 282 may store data and program code for base station 110 and UE 120, respectively. In some aspects, memory 242 and / or memory 282 may include a non-transitory computer-readable medium storing one or more instructions (e.g., code and / or program code) for wireless communication. For example, one or more instructions, when executed by one or more processors of base station 110 and / or UE 120 (e.g., directly, or after compilation, translation, and / or interpretation), may cause one or more processors, UE 120, and / or base station 110 to perform or instruct, for example... Figure 5 Process 500 Figure 6 The operation of process 600 and / or other processes as described herein. In some aspects, execution instructions may include run instructions, translation instructions, compilation instructions and / or interpretation instructions, and other examples.

[0045] In some aspects, UE (e.g., Figure 7 The apparatus 700 and / or UE 120 may include: a unit for receiving an IMS configuration message from an NR cell; a unit for receiving an instruction for backing up to a legacy cell from an NR cell; a unit for storing a response to the IMS configuration message based at least in part on receiving the instruction for backing up; and / or a unit for sending a response to the IMS configuration message to a legacy cell before sending another IMS message. The unit for the UE to perform the operations described herein may include, for example, one or more of antenna 252, demodulator 254, MIMO detector 256, receive processor 258, transmit processor 264, TX MIMO processor 266, modulator 254, controller / processor 280, or memory 282.

[0046] In some aspects, the UE may further include: a unit for determining that a protocol data unit (PDU) including a response is associated with a 5QI mapped to a stored 5G Quality of Service (QoS) identifier (5QI) value, and the response is stored at least in part based on this determination. Additionally, the UE may include a unit for discarding one or more additional PDUs associated with one or more 5QI values ​​not mapped to a stored 5QI value.

[0047] In some aspects, the UE may also include a unit for sending an IMS ringing message to the legacy cell after sending a response. Alternatively, the UE may include a unit for establishing a radio resource control (RRC) connection with the legacy cell before sending a response.

[0048] In some aspects, base stations (e.g., Figure 8 The device 800 and / or base station 110 may include: for receiving signals from the UE (e.g., Figure 7 The apparatus 700 and / or UE 120 may receive a connection request, wherein the connection request is at least in part based on an instruction for backing up from the NR cell; and / or a unit for receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message. The unit for the base station to perform the operations described herein may include, for example, one or more of the following: a transmit processor 220, a TX MIMO processor 230, a modulator 232, an antenna 234, a demodulator 232, a MIMO detector 236, a receive processor 238, a controller / processor 240, a memory 242, or a scheduler 246.

[0049] In some aspects, the base station may also include a unit for receiving an IMS ringing message from the UE after receiving a response. Alternatively, the base station may include a unit for establishing an RRC connection with the UE before receiving a response.

[0050] Although Figure 2 The boxes in the diagram are shown as different components, but the functions described above with respect to these boxes can be implemented in a single hardware, software, or combined component, or in various combinations of components. For example, the functions described with respect to transmit processor 264, receive processor 258, and / or TX MIMO processor 266 can be performed by or under the control of controller / processor 280.

[0051] As pointed out above, Figure 2 This is provided as an example. Other examples may differ from the one provided. Figure 2 The example described.

[0052] Figure 3This is a diagram illustrating example 300 of a voice call failure during EPS rollback according to various aspects of this disclosure. Figure 3 As shown, the UE can communicate with NR cells (e.g., via NR base stations) and legacy cells (e.g., via legacy base stations). NR cells can be part of a standalone (SA) 5G network or a non-standalone (NSA) 5G network using the same core network as the legacy network that includes legacy cells. NR cells and legacy cells can share the IMS architecture, enabling NR cells to initiate finalization and conduct IMS sessions on legacy cells, as described in further detail below.

[0053] In Example 300, the UE can connect to an NR cell and request a voice call. As shown in conjunction with reference numeral 305, the NR base station can initiate an IMS session with the UE. For example, the NR base station can send an INVITE message as defined in Request for Comments (RFC) 3312 of the Network Working Group and / or another standard. Additionally, after reserving one or more resources on the IMS architecture, the NR base station can send an UPDATE message as defined in RFC 3312 and / or another standard. The IMS session allows the NR base station to deliver IP multimedia services to the UE to process the requested voice call using IP packet switching. For example, both Voice over New Radio (VoNR) and Voice over LTE (VoLTE) can rely on IMS.

[0054] As shown in conjunction with reference to reference numeral 310 in the accompanying drawings, the NR base station can also initiate EPS backoff. For example, the NR base station can send an RRC Connection Reconfiguration message as defined in 3GPP specifications and / or another standard. EPS backoff allows the UE to use the LTE network or other legacy networks to complete the requested voice call. For example, where NR coverage may be less reliable in the UE's location, the NR base station may initiate EPS backoff to reduce the risk that the requested voice call will be dropped. Alternatively, the UE and / or the NR base station may not be configured for VoNR service.

[0055] As shown in conjunction with reference numeral 315 in the accompanying drawings, the UE can establish a connection with a legacy network (e.g., via a legacy base station, which may be the same as or different from the NR base station). For example, the UE can initiate an RRC connection with a legacy base station, which may include establishing a Random Access Channel (RACH) with the legacy base station. However, before establishing a connection with the legacy network, the UE may not be able to send a response to an UPDATE message from the NR base station. For example, the UE may not be able to send a 200 OK message as defined in RFC 3312 and / or another standard. Additionally, establishing a connection with the legacy network completes a handover initiated by EPS backoff, which causes the UE to release the PDCP entity associated with the NR network (e.g., according to 3GPP specification 38.331 and / or another standard) and discard all PDUs, including previously generated 200 OK messages (e.g., according to 3GPP specification 38.323 and / or another standard).

[0056] Therefore, as shown in conjunction with reference numeral 320 in the attached figure, the UE can continue to ring the traditional base station. For example, the UE can send a 180 ring message as defined in RFC 3312 and / or another standard. Because any pending 200 OK messages have been discarded, the UE attempts to initiate an IMS session. However, the NR cell does not receive the 200 OK message, and therefore the IMS architecture cannot confirm any preconditions included in the UPDATE message. For example, preconditions may include a QoS indicator, an indicator regarding the UE being configured as an EPS bearer, and / or another precondition for initiating an IMS session.

[0057] Therefore, as shown in conjunction with reference numeral 325, a legacy base station can attempt to retransmit the UPDATE message. However, as shown in conjunction with reference numeral 330, the UE can send a 200 OK message that still does not meet the preconditions included in the UPDATE message. For example, the UE can send the 200 OK message at least in part based on the expectation of a provisional response acknowledgment (PRACK) from the legacy base station rather than a retransmission of the UPDATE message. Therefore, as shown in conjunction with reference numeral 335, an IMS session will not be established, and the voice call will fail.

[0058] As pointed out above, Figure 3 This is provided as an example. Other examples may differ from the one provided. Figure 3 The example described.

[0059] Some of the technologies and apparatus described herein enable a UE (e.g., UE 120) to retain a PDU including an IMS response (e.g., a 200 OK message as defined in RFC 3312 and / or another standard) during a fallback to a legacy network (e.g., EPS fallback to an LTE network). Furthermore, after the UE completes the handover from the NR network to the legacy network, the UE can deliver an IMS response to the legacy network. Therefore, an IMS session will be successfully established, and voice calls will not fail. This improves the reliability and quality of voice calls, and enhances the user experience.

[0060] Figure 4 This is a diagram illustrating example 400 associated with IMS signaling during fallback to a legacy cell, according to various aspects of this disclosure. Figure 4 As shown, Example 400 includes communication between base station 110a and UE 120, and between base station 110b and UE 120. In some aspects, base station 110a and UE 120 may be included in a wireless network (such as wireless network 100). For example, base station 110a may be included in an NR cell of a 5G network. Similarly, base station 110b and UE 120 may be included in another wireless network. For example, base station 110b may be included in a legacy cell of a legacy network (e.g., an LTE network and / or another legacy network). In some aspects, NR cells and legacy cells may share an IMS architecture, enabling NR cells to initiate finalization and conduct IMS sessions on legacy cells, as described in further detail below.

[0061] In Example 400, UE 120 can connect to base station 110a and request a voice call. Therefore, as shown in conjunction with reference numeral 405, base station 110a can send, and UE 120 can receive, IMS configuration messages. For example, base station 110a can send an INVITE message as defined in RFC 3312 and / or another standard. Additionally, after reserving one or more resources on the IMS architecture, base station 110a can send an UPDATE message as defined in RFC 3312 and / or another standard. The IMS session can allow base station 110a to deliver IP multimedia services to UE 120 to handle the requested voice call using IP packet switching. For example, both VoNR and VoLTE can rely on IMS.

[0062] As shown in conjunction with reference numeral 410, base station 110a can send, and UE 120 can receive, instructions for fallback to a legacy cell. For example, base station 110a can send an RRC Connection Reconfiguration message as defined in 3GPP specifications and / or another standard. EPS fallback allows UE 120 to use a legacy cell to complete the requested voice call. For example, where UE 120 is located, NR coverage may be unreliable, causing base station 110a to initiate EPS fallback to reduce the risk that the requested voice call will be dropped. Alternatively, UE 120 and / or base station 110a may not support VoNR.

[0063] As shown in conjunction with reference numeral 415, UE 120 may store the response to the IMS configuration message at least in part based on receiving instructions for rollback. For example, UE 120 may generate a 200 OK message (e.g., as defined in RFC 3312 and / or another standard) at least in part based on receiving the IMS configuration message. However, UE 120 may receive instructions for rollback before sending the response. Therefore, UE 120 may alternatively store the response. For example, UE 120 may store the response as a PDU within a PDCP entity.

[0064] In some respects, UE 120 may determine that the PDU including the response is associated with a 5QI mapped to a stored 5QI value. For example, the response may be associated with a 5QI mapped to a 5QI value 5 according to 3GPP Technical Specification 23.501 and / or another standard. Therefore, UE 120 may store the response based at least in part on this determination.

[0065] In some respects, UE 120 may also discard one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to the stored 5QI values. For example, UE 120 may release PDCP entities associated with the 5G network (e.g., according to 3GPP Technical Specification 38.331 and / or another standard) and discard all PDUs except those stored, including the response PDUs.

[0066] As shown in conjunction with reference numeral 420 in the accompanying drawings, UE 120 can establish an RRC connection with base station 110b. For example, UE 120 can establish an RRC connection at least in part based on instructions for fallback. In some aspects, UE 120 can establish an RRC connection at least in part by establishing a RACH with base station 110b.

[0067] As shown in conjunction with reference numeral 425, UE 120 can send a response to the IMS configuration message before another IMS message, and base station 110b can receive this response. Therefore, the IMS architecture can acknowledge one or more preconditions included in the UPDATE message. For example, preconditions may include a QoS indicator, an indicator regarding UE 120 being configured as an EPS bearer, and / or another precondition for starting an IMS session. Because UE 120 is now configured as an EPS bearer on a legacy network and / or because the legacy network should provide sufficient QoS to UE 120, UE 120 can acknowledge one or more preconditions in the response.

[0068] As shown in conjunction with reference numeral 430 in the accompanying drawings, UE 120 may send an IMS ringing message after a response, and base station 110b may receive the IMS ringing message. For example, the UE may send a 180 ringing message as defined in RFC 3312 and / or another standard.

[0069] Therefore, as shown in conjunction with reference numeral 435, UE 120 and base station 110b can successfully establish the requested voice call. By using the combination... Figure 4 The described technology allows UE 120 to retain a PDU including an IMS response (e.g., a 200 OK message as defined in RFC 3312 and / or another standard) during fallback to a legacy network. Furthermore, after UE 120 completes the handover from the 5G network to the legacy network, UE 120 can send an IMS response to the legacy network. Therefore, an IMS session will be successfully established, and voice calls will not fail, improving the reliability and quality of voice calls and enhancing the user experience.

[0070] As pointed out above, Figure 4 This is provided as an example. Other examples may differ from the one provided. Figure 4 The example described.

[0071] Figure 5 This is a diagram illustrating, for example, an example process 500 performed by a UE according to various aspects of this disclosure. Example process 500 is where the UE (e.g., Figure 7 Examples of devices 700 and / or UE 120 performing operations associated with IMS signaling during fallback to a legacy cell.

[0072] like Figure 5 As shown, in some aspects, process 500 may include: receiving an IMS configuration message from an NR cell (block 510). For example, the UE (e.g., using...) Figure 7 The receiving component 702 described herein can receive IMS configuration messages from the NR cell, as described above.

[0073] like Figure 5 As further shown, in some aspects, process 500 may include receiving instructions from an NR cell for backing up to a legacy cell (block 520). For example, the UE (e.g., using receiving component 702) may receive instructions from an NR cell for backing up to a legacy cell, as described above.

[0074] like Figure 5 As further shown, in some aspects, process 500 may include: storing a response to an IMS configuration message based at least in part on receiving an instruction for rollback (box 530). For example, the UE (e.g., using...) Figure 7 The storage component 708 described herein can store responses to IMS configuration messages, as described above.

[0075] like Figure 5 As further shown, in some aspects, process 500 may include: sending a response to the IMS configuration message to the legacy cell before sending another IMS message (box 540). For example, the UE (e.g., using...) Figure 7 The transmitting component 704 described herein can send a response to the IMS configuration message to the traditional cell before sending another IMS message, as described above.

[0076] Process 500 may include additional aspects, such as any single aspect or any combination thereof described below and / or in conjunction with one or more other process descriptions elsewhere described herein.

[0077] In the first aspect, the UE does not support VoNR.

[0078] In the second aspect, either alone or in combination with the first aspect, process 500 further includes: determining (e.g., using...) Figure 7 The determining component 710 depicted includes a response PDU associated with a 5QI mapped to a stored 5QI value, and the response is stored at least in part based on the determining.

[0079] In the third aspect, either alone or in combination with one or more of the first and second aspects, process 500 further includes: discarding (e.g., using storage component 708) one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to storage.

[0080] In the fourth aspect, either alone or in combination with one or more of the first to third aspects, process 500 further includes: sending an IMS ringing message to the traditional cell (e.g., using the sending component 704) after sending a response.

[0081] In the fifth aspect, either alone or in combination with one or more of the first to fourth aspects, process 500 includes: establishing an RRC connection with a traditional cell (e.g., using a receiving component 702 and / or a transmitting component 704) prior to transmitting a response.

[0082] In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the RRC connection is established at least in part by establishing a RACH with a traditional cell (e.g., using the receive component 702 and / or the transmit component 704).

[0083] In the seventh aspect, either alone or in combination with one or more of the first to sixth aspects, the response is stored as a PDU within the PDCP entity.

[0084] Although Figure 5 An example box of process 500 is shown, but in some aspects, process 500 may include... Figure 5 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 500 may be executed in parallel.

[0085] Figure 6 This is a diagram illustrating, for example, an example process 600 performed by a base station according to various aspects of this disclosure. Example process 600 is where a base station (e.g., Figure 8 An example of the device 800 and / or base station 110 performing operations associated with IMS signaling during fallback to a legacy cell.

[0086] like Figure 6 As shown, in some aspects, process 600 may include: from the UE (e.g., Figure 7 The device 700 and / or UE120) receives a connection request (box 610). For example, the base station (e.g., using...) Figure 8 The receiving component 802 depicted can receive a connection request from the UE, as described above. In some aspects, the connection request is at least in part based on instructions for backing up from the NR cell.

[0087] like Figure 6 As further shown, in some aspects, process 600 may include receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message (block 620). For example, the base station (e.g., using receiving component 802) may receive from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message, as described above.

[0088] Process 600 may include additional aspects, such as any single aspect or any combination thereof described below and / or in conjunction with one or more other process descriptions elsewhere described herein.

[0089] In the first aspect, base stations are associated with traditional cells.

[0090] In the second aspect, either alone or in combination with the first aspect, the response PDU is associated with a 5QI value mapped to the storage.

[0091] In the third aspect, either alone or in combination with one or more of the first and second aspects, process 600 further includes: receiving an IMS ringing message from the UE (e.g., using receiving component 802) after receiving a response.

[0092] In the fourth aspect, either alone or in combination with one or more of the first to third aspects, process 600 further includes: establishing (e.g., using...) an agreement with the UE before receiving a response. Figure 8 The receiving component 802 and / or transmitting component 804 depicted in the diagram are connected via RRC.

[0093] In the fifth aspect, either alone or in combination with one or more of the first to fourth aspects, the RRC connection is established at least in part by establishing a RACH with the UE (e.g., using the receiving component 802 and / or the transmitting component 804).

[0094] In the sixth aspect, either alone or in combination with one or more of the first to fifth aspects, the response is included in the PDU within the PDCP entity.

[0095] Although Figure 6 An example box of process 600 is shown, but in some aspects, process 600 may include... Figure 6 The boxes depicted in the diagram are compared to additional boxes, fewer boxes, different boxes, or boxes arranged in a different manner. Alternatively, two or more boxes in process 600 may be executed in parallel.

[0096] Figure 7This is a block diagram of an example device 700 for wireless communication. Device 700 may be a UE, or a UE may include device 700. In some aspects, device 700 includes a receiving component 702 and a transmitting component 704, which can communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, device 700 can use the receiving component 702 and the transmitting component 704 to communicate with another device 706 (such as a UE, a base station, or another wireless communication device). As further shown, device 700 may include one or more of a storage component 708 or a determining component 710, and other examples.

[0097] In some respects, device 700 can be configured to perform the functions described herein. Figure 4 One or more operations described herein. Alternatively or concurrently, the apparatus 700 may be configured to perform one or more processes described herein, such as... Figure 5 The process 500 or a combination thereof. In some respects, Figure 7 The device 700 and / or one or more components shown may include the elements described above. Figure 2 One or more components of the UE as described. Alternatively or in addition, Figure 7 One or more components shown can be combined with the above. Figure 2 The description refers to implementation within one or more components. Alternatively, one or more components in the set of components may be implemented, at least partially, as software stored in memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or processor to perform the function or operation of the component.

[0098] Receiver 702 may receive communications from device 706, such as reference signals, control information, data communications, or combinations thereof. Receiver 702 may provide the received communications to one or more other components of device 700. In some aspects, receiver 702 may perform signal processing on the received communications (e.g., filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, demapping, equalization, interference cancellation, or decoding, and other examples), and may provide the processed signal to one or more other components of device 706. In some aspects, receiver 702 may include the elements described above. Figure 2 The described UE includes one or more antennas, demodulators, MIMO detectors, receiver processors, controllers / processors, memory, or combinations thereof.

[0099] Transmitting component 704 can transmit communications, such as reference signals, control information, data communications, or combinations thereof, to device 706. In some aspects, one or more other components of device 706 can generate communications and provide the generated communications to transmitting component 704 for transmission to device 706. In some aspects, transmitting component 706 can perform signal processing on the generated communications (e.g., filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, and other examples), and can transmit the processed signal to device 706. In some aspects, transmitting component 704 can include the combinations described above. Figure 2 The described UE includes one or more antennas, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof. In some aspects, the transmit component 704 may be co-located with the receive component 702 in a transceiver.

[0100] In some aspects, receiving component 702 can receive IMS configuration messages from an NR cell (e.g., via device 706). Additionally, receiving component 702 can receive instructions for fallback to a legacy cell from an NR cell (e.g., via device 706). Therefore, storage component 708 can store responses to IMS configuration messages based at least in part on the fallback instructions received by receiving component 702. In some aspects, storage component 708 may include the above-described combinations... Figure 2 The described UE includes a transmitting processor, a receiving processor, a controller / processor, a memory, or a combination thereof. Additionally, the transmitting component 704 can send a response to the IMS configuration message to the legacy cell before transmitting another IMS message.

[0101] In some aspects, determining component 710 may determine that the PDU including the response is associated with a 5QI value mapped to storage. In some aspects, determining component 710 may include the above-described combination of... Figure 2 The described UE includes a transmitting processor, a receiving processor, a controller / processor, a memory, or a combination thereof. Therefore, the storage component 708 can store responses based at least in part on the output from the determining component 710.

[0102] In some respects, storage component 708 may discard one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to storage.

[0103] In some aspects, the transmitting component 704 may send an IMS ringing message to the legacy cell after sending a response. Alternatively, the receiving component 702 and / or the transmitting component 704 may establish an RRC connection with the legacy cell before the transmitting component 704 sends a response.

[0104] Figure 7The number and arrangement of components shown are provided as an example. In reality, they can exist in combination with... Figure 7 The components shown are compared to additional components, fewer components, different components, or components arranged in a different way. Furthermore, Figure 7 The two or more components shown can be implemented within a single component, or Figure 7 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 7 The set (one or more) components shown can perform actions described by Figure 7 The other set of components shown performs one or more functions.

[0105] Figure 8 This is a block diagram of an example device 800 for wireless communication. Device 800 may be a base station, or a base station may include device 800. In some aspects, device 800 includes a receiving component 802 and a transmitting component 804, which can communicate with each other (e.g., via one or more buses and / or one or more other components). As shown, device 800 can use the receiving component 802 and the transmitting component 804 to communicate with another device 806 (such as a UE, a base station, or another wireless communication device). As further shown, device 800 may include an IMS component 808 and other examples.

[0106] In some respects, device 800 can be configured to perform the functions described herein. Figure 4 One or more operations described herein. Alternatively or concurrently, the apparatus 800 may be configured to perform one or more processes described herein, such as... Figure 6 The process 600 or a combination thereof. In some respects, Figure 8 The device 800 and / or one or more components shown may include the elements described above. Figure 2 One or more components of the described base station. Alternatively, Figure 8 One or more components shown can be combined with the above. Figure 2 The description refers to implementation within one or more components. Alternatively, one or more components in the set of components may be implemented, at least partially, as software stored in memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or processor to perform the function or operation of the component.

[0107] Receiver 802 may receive communications from device 806, such as reference signals, control information, data communications, or combinations thereof. Receiver 802 may provide the received communications to one or more other components of device 800. In some aspects, receiver 802 may perform signal processing on the received communications (e.g., filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, demapping, equalization, interference cancellation, or decoding, and other examples), and may provide the processed signal to one or more other components of device 806. In some aspects, receiver 802 may include the elements described above. Figure 2 The described base station includes one or more antennas, demodulators, MIMO detectors, receiver processors, controllers / processors, memory, or combinations thereof.

[0108] Transmitting component 804 can transmit communications, such as reference signals, control information, data communications, or combinations thereof, to device 806. In some aspects, one or more other components of device 806 can generate communications and provide the generated communications to transmitting component 804 for transmission to device 806. In some aspects, transmitting component 806 can perform signal processing (e.g., filtering, amplification, modulation, digital-to-analog conversion, multiplexing, interleaving, mapping, or encoding, and other examples) on the generated communications and can transmit the processed signal to device 806. In some aspects, transmitting component 804 can include the combinations described above. Figure 2 The described base station includes one or more antennas, a modulator, a transmit MIMO processor, a transmit processor, a controller / processor, a memory, or a combination thereof. In some aspects, the transmit component 804 may be co-located with the receive component 802 in a transceiver.

[0109] In some aspects, receiving component 802 may receive a connection request from device 806. In some aspects, the connection request is at least partially based on instructions for fallback from the NR cell. Additionally, receiving component 802 may receive a response to an IMS configuration message sent by the NR cell from device 806 before receiving another IMS message. For example, IMS component 808 may have already received information from the IMS architecture regarding an IMS session initiated by the NR cell. In some aspects, IMS component 808 may include the above-described combinations... Figure 2 The described base station includes one or more antennas, demodulators, MIMO detectors, receiver processors, modulators, transmit MIMO processors, transmit processors, controllers / processors, memory, or combinations thereof.

[0110] In some aspects, receiving component 802 may also receive IMS ringing messages from device 806 after receiving a response. Alternatively or additionally, receiving component 802 and / or transmitting component 804 may establish an RRC connection with device 806 before receiving component 802 receives a response.

[0111] Figure 8 The number and arrangement of components shown are provided as an example. In reality, they can exist in combination with... Figure 8 The components shown are compared to additional components, fewer components, different components, or components arranged in a different way. Furthermore, Figure 8 The two or more components shown can be implemented within a single component, or Figure 8 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 8 The set (one or more) components shown can perform actions described by Figure 8 The other set of components shown performs one or more functions.

[0112] The following provides a summary of some aspects of this disclosure:

[0113] Aspect 1: A method of wireless communication performed by a user equipment (UE), comprising: receiving an Internet Protocol Multimedia Subsystem (IMS) configuration message from a new radio (NR) cell; receiving an instruction from the NR cell for falling back to a legacy cell; storing a response to the IMS configuration message based at least in part on receiving the instruction for falling back; and sending the response to the IMS configuration message to the legacy cell before sending another IMS message.

[0114] Aspect 2: According to the method of aspect 1, wherein the UE does not support NR-based voice (VoNR).

[0115] Aspect 3: The method according to any one of Aspects 1 to 2 further includes: determining that a Protocol Data Unit (PDU) including the response is associated with a 5QI mapped to a stored 5G Quality of Service (QoS) Identifier (5QI) value, wherein the response is stored at least in part based on the determination.

[0116] Aspect 4: The method according to aspect 3 further includes: discarding one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to the stored 5QI values.

[0117] Aspect 5: The method according to any one of Aspects 1 to 4 further includes: sending an IMS ringing message to the conventional cell after sending the response.

[0118] Aspect 6: The method according to any one of Aspects 1 to 5 further includes: establishing a Radio Resource Control (RRC) connection with the conventional cell before sending the response.

[0119] Aspect 7: According to the method of aspect 6, wherein the RRC connection is established at least in part by establishing a random access channel (RACH) with the traditional cell.

[0120] Aspect 8: The method according to any one of Aspects 1 to 7, wherein the response is stored as a Protocol Data Unit (PDU) within a Packet Data Convergence Protocol (PDCP) entity.

[0121] Aspect 9: A method of wireless communication performed by a base station, comprising: receiving a request for connection from a UE, wherein the request for connection is at least partially based on an instruction for fallback from an NR cell; and receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another IMS message.

[0122] Aspect 10: According to the method of aspect 9, wherein the base station is associated with a conventional cell.

[0123] Aspect 11: The method according to any one of Aspects 9 to 10, wherein the PDU including the response is associated with a 5QI mapped to a stored 5QI value.

[0124] Aspect 12: The method according to any one of Aspects 9 to 11 further includes: receiving an IMS ringing message from the UE after receiving the response.

[0125] Aspect 13: The method according to any one of Aspects 9 to 12 further includes: establishing an RRC connection with the UE before receiving the response.

[0126] Aspect 14: The method according to aspect 13, wherein the RRC connection is established at least in part by establishing a RACH with the UE.

[0127] Aspect 15: The method according to any one of Aspects 9 to 14, wherein the response is included in a PDU within the PDCP entity.

[0128] Aspect 16: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to one or more of aspects 1-8.

[0129] Aspect 17: An apparatus for wireless communication, comprising a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to perform the method according to one or more of aspects 1-8.

[0130] Aspect 18: An apparatus for wireless communication, comprising at least one unit for performing the method according to one or more of aspects 1-8.

[0131] Aspect 19: A non-transitory computer-readable medium storing code for wireless communication, said code including instructions executable by a processor to perform the methods described in one or more of aspects 1-8.

[0132] Aspect 20: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform the method according to one or more aspects of aspects 1-8.

[0133] Aspect 21: An apparatus for wireless communication at a device, comprising: a processor; a memory coupled to the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform the method according to one or more of aspects 9-15.

[0134] Aspect 22: An apparatus for wireless communication, comprising a memory and one or more processors coupled to the memory, the memory and the one or more processors being configured to perform the method according to one or more of aspects 9-15.

[0135] Aspect 23: An apparatus for wireless communication, comprising at least one unit for performing the method according to one or more of aspects 9-15.

[0136] Aspect 24: A non-transitory computer-readable medium storing code for wireless communication, said code including instructions executable by a processor to perform the methods described in one or more of aspects 9-15.

[0137] Aspect 25: A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising one or more instructions which, when executed by one or more processors of a device, cause the device to perform the method according to one or more aspects of aspects 9-15.

[0138] The foregoing disclosure provides explanations and descriptions, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made based on the foregoing disclosure, or modifications and variations may be derived from practice in the aspects.

[0139] As used herein, the term "component" is intended to be interpreted broadly as hardware and / or a combination of hardware and software. Whether referred to as software, firmware, middleware, microcode, hardware description language, or other names, "software" should be interpreted broadly as instructions, instruction sets, code, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures and / or functions, and other examples. As used herein, processors are implemented using hardware and / or a combination of hardware and software. It will be apparent that the systems and / or methods described herein can be implemented using various forms of hardware and / or combinations of hardware and software. The actual specialized control hardware or software code used to implement these systems and / or methods is not a limitation in any respect. Therefore, while the operation and behavior of systems and / or methods are described herein without reference to specific software code, it is to be understood that software and hardware can be designed to implement systems and / or methods, at least in part, based on the descriptions herein.

[0140] As used in this article, depending on the context, satisfying the threshold can refer to a value greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, etc.

[0141] Even if a specific combination of features is recited in the claims and / or disclosed in the specification, such combinations are not intended to limit the disclosure of the aspects. In fact, many of these features can be combined in ways that are not specifically recited in the claims and / or specifically disclosed in the specification. While each dependent claim listed below may directly depend on only one claim, the disclosure of an aspect includes a combination of each dependent claim with every other claim in the claim set. As used herein, the phrase “at least one of” in the list of items refers to any combination of those items, including individual members. For example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination of multiples of the same element (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other ordering of a, b, and c).

[0142] None of the elements, actions, or instructions used herein should be construed as critical or necessary unless explicitly stated otherwise. Furthermore, as used herein, the articles “a” and “an” are intended to include one or more items and are interchangeable with “one or more.” Furthermore, as used herein, the article “the” is intended to include one or more items referenced in combination with the article “the” and is interchangeable with “one or more.” Furthermore, as used herein, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items) and are interchangeable with “one or more.” Where only one item is anticipated, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “has,” “have,” “having,” etc., are intended to be open-ended terms. Furthermore, unless explicitly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.” Furthermore, as used herein, the term “or” is intended to be inclusive when used in a series and may be used interchangeably with “and / or” unless otherwise expressly stated (e.g., if used in conjunction with “any” or “only one of”).

Claims

1. A user equipment (UE) for wireless communication, comprising: Memory; as well as One or more processors are operatively coupled to the memory, and the memory and the one or more processors are configured to: Receive Internet Protocol Multimedia Subsystem (IMS) configuration messages from a New Radio (NR) cell, wherein the IMS configuration messages include UPDATE messages; Receive instructions from the NR cell for backing up to a traditional cell; The response to the IMS configuration message is stored at least in part based on receiving the instruction for rollback; and The response to the IMS configuration message is sent to the traditional cell before sending another IMS message.

2. The UE according to claim 1, wherein, The UE does not support NR-based voice (VoNR).

3. The UE according to claim 1 or claim 2, wherein, The memory and the one or more processors are further configured to: The protocol data unit (PDU) including the response is determined to be associated with a 5QI that is mapped to a stored 5G quality of service (QoS) identifier (5QI) value, wherein the response is stored at least in part based on the determination.

4. The UE according to claim 3, wherein, The memory and the one or more processors are further configured to: Discard one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to the stored 5QI values.

5. The UE according to claim 1, wherein, The memory and the one or more processors are further configured to: After sending the response, an IMS ringing message is sent to the traditional cell.

6. The UE according to claim 1, wherein, The memory and the one or more processors are further configured to: Before sending the response, a radio resource control (RRC) connection is established with the traditional cell.

7. The UE according to claim 6, wherein, The RRC connection is established, at least in part, by establishing a random access channel (RACH) with the traditional cell.

8. The UE according to claim 1, wherein, The response is stored as a Protocol Data Unit (PDU) within the Packet Data Convergence Protocol (PDCP) entity.

9. A base station for wireless communication, comprising: Memory; as well as One or more processors are operatively coupled to the memory, and the memory and the one or more processors are configured to: Receive a connection request from a user equipment (UE), wherein the connection request is at least in part based on instructions for backing up from a new radio (NR) cell; and Before receiving another Internet Protocol Multimedia Subsystem (IMS) message, the UE receives a response to an IMS configuration message sent by the NR cell, wherein the IMS configuration message includes an UPDATE message.

10. The base station according to claim 9, wherein, The base station is associated with a traditional cell.

11. The base station according to claim 9 or claim 10, wherein, The Protocol Data Unit (PDU) including the response is associated with a 5QI that is mapped to a stored 5G Quality of Service (QoS) Identifier (5QI) value.

12. The base station according to claim 9, wherein, The memory and the one or more processors are further configured to: After receiving the response, an IMS ringing message is received from the UE.

13. The base station according to claim 9, wherein, The memory and the one or more processors are further configured to: A radio resource control (RRC) connection is established with the UE before receiving the response.

14. The base station according to claim 13, wherein, The RRC connection is established, at least in part, by establishing a random access channel (RACH) with the UE.

15. The base station according to claim 9, wherein, The response is included in a Protocol Data Unit (PDU) within the Packet Data Convergence Protocol (PDCP) entity.

16. A method for wireless communication performed by a user equipment (UE), comprising: Receive Internet Protocol Multimedia Subsystem (IMS) configuration messages from a New Radio (NR) cell, wherein the IMS configuration messages include UPDATE messages; Receive instructions from the NR cell for backing up to a traditional cell; The response to the IMS configuration message is stored at least in part based on receiving the instruction for rollback; and The response to the IMS configuration message is sent to the traditional cell before sending another IMS message.

17. The method according to claim 16, wherein, The UE does not support NR-based voice (VoNR).

18. The method according to claim 16 or claim 17, further comprising: The protocol data unit (PDU) including the response is determined to be associated with a 5QI that is mapped to a stored 5G quality of service (QoS) identifier (5QI) value, wherein the response is stored at least in part based on the determination.

19. The method of claim 18, further comprising: Discard one or more additional PDUs associated with one or more 5QI values ​​that are not mapped to the stored 5QI values.

20. The method of claim 16, further comprising: After sending the response, an IMS ringing message is sent to the traditional cell.

21. The method of claim 16, further comprising: Before sending the response, a radio resource control (RRC) connection is established with the traditional cell.

22. The method according to claim 21, wherein, The RRC connection is established, at least in part, by establishing a random access channel (RACH) with the traditional cell.

23. The method according to claim 16, wherein, The response is stored as a Protocol Data Unit (PDU) within the Packet Data Convergence Protocol (PDCP) entity.

24. A method for wireless communication performed by a base station, comprising: Receive a connection request from a user equipment (UE), wherein the connection request is at least in part based on instructions for backing up from a new radio (NR) cell; and Before receiving another Internet Protocol Multimedia Subsystem (IMS) message, the UE receives a response to an IMS configuration message sent by the NR cell, wherein the IMS configuration message includes an UPDATE message.

25. The method according to claim 24, wherein, The base station is associated with a traditional cell.

26. The method according to claim 24 or claim 25, wherein, The Protocol Data Unit (PDU) including the response is associated with a 5QI that is mapped to a stored 5G Quality of Service (QoS) Identifier (5QI) value.

27. The method of claim 24, further comprising: After receiving the response, an IMS ringing message is received from the UE.

28. The method of claim 24, further comprising: A radio resource control (RRC) connection is established with the UE before receiving the response.

29. The method according to claim 28, wherein, The RRC connection is established, at least in part, by establishing a random access channel (RACH) with the UE.

30. The method according to claim 24, wherein, The response is included in a Protocol Data Unit (PDU) within the Packet Data Convergence Protocol (PDCP) entity.

31. A non-transitory computer-readable medium storing an instruction set for wireless communication, the instruction set comprising: One or more instructions, which, when executed by one or more processors of a user equipment (UE), cause the UE to perform the following operations: Receive Internet Protocol Multimedia Subsystem (IMS) configuration messages from a New Radio (NR) cell, wherein the IMS configuration messages include UPDATE messages; Receive instructions from the NR cell for backing up to a traditional cell; The response to the IMS configuration message is stored at least in part based on receiving the instruction for rollback; and The response to the IMS configuration message is sent to the traditional cell before sending another IMS message.

32. A non-transitory computer-readable medium storing a set of instructions for wireless communication, the set of instructions comprising: One or more instructions, which, when executed by one or more processors of the base station, cause the base station to perform the following operations: Receive a connection request from a user equipment (UE), wherein the connection request is at least in part based on instructions for backing up from a new radio (NR) cell; and Before receiving another Internet Protocol Multimedia Subsystem (IMS) message, the UE receives a response to an IMS configuration message sent by the NR cell, wherein the IMS configuration message includes an UPDATE message.

33. An apparatus for wireless communication, comprising: A unit for receiving Internet Protocol Multimedia Subsystem (IMS) configuration messages from a New Radio (NR) cell, wherein the IMS configuration messages include UPDATE messages; A unit for receiving instructions from the NR cell for backing up to a legacy cell; A unit for storing a response to the IMS configuration message based at least in part on receiving the instruction for rollback; and A unit for sending the response to the IMS configuration message to the traditional cell before sending another IMS message.

34. An apparatus for wireless communication, comprising: A unit for receiving a connection request from a user equipment (UE), wherein the connection request is at least in part based on instructions for backing up from a new radio (NR) cell; and A unit for receiving from the UE a response to an IMS configuration message sent by the NR cell before receiving another Internet Protocol Multimedia Subsystem (IMS) message, wherein the IMS configuration message includes an UPDATE message.

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