WO2021151256A1

WO2021151256A1 - Radio access technology downgrading

Info

Publication number: WO2021151256A1
Application number: PCT/CN2020/074132
Authority: WO
Inventors: Venkata Durga Vinod CHIKKALA; Naga Chandan Babu Gudivada; Rajendra Prasad NELUROUTH; Phani Pradeep Kumar KOTHAPALLI VENKATA; Jian Li; Meng Liu
Original assignee: Qualcomm Incorporated
Priority date: 2020-02-01
Filing date: 2020-02-01
Publication date: 2021-08-05

Abstract

A user equipment (UE) determines that a trigger has occurred. The trigger indicates that a primary radio access technology should not be utilized. The UE enters into an RRC connected state with a base station utilizing a secondary radio access technology without accessing data related to the primary radio access technology upon determining that the trigger has occurred. The UE enters into an RRC connected state with the base station utilizing the primary radio access technology upon determining that the trigger event has not occurred.

Description

RADIO ACCESS TECHNOLOGY DOWNGRADING

BACKGROUND Technical Field

The present disclosure relates generally to communication systems, and more particularly, to a user equipment.

Introduction

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. 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, and time division synchronous code division multiple access (TD-SCDMA) systems.

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR) . 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT) ) , and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB) , massive machine type communications (mMTC) , and ultra reliable low latency communications (URLLC) . Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

SUMMARY

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

Transitioning (e.g., upgrading) a mobile communication network from a first radio access technology (RAT) to a second RAT may happen over time. During the process, the mobile communication network may be partially deployed for the first RAT. A user equipment (UE) utilizing the first RAT to communicate with the mobile communication network may be exposed to security risks, may experience poor service, or may experience power drain from transitioning between the first RAT and the second RAT.

A UE determines that a trigger has occurred. The trigger indicates that a primary radio access technology should not be utilized. The UE enters into an RRC connected state with a base station utilizing a secondary radio access technology without accessing data related to the primary radio access technology upon determining that the trigger has occurred, and does not access the base station utilizing the primary radio access technology. The UE enters into an RRC connected state with the base station utilizing the primary radio access technology upon determining that the trigger event has not occurred.

In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus determines whether a trigger has occurred, the trigger indicating that a primary radio access technology should not be utilized, enters into an RRC connected state with a base station utilizing a secondary radio access technology without accessing data related to the primary radio access technology upon determining that the trigger has occurred, and enters into an RRC connected state with the base station utilizing the primary radio access technology upon determining that the trigger event has not occurred.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network.

FIGs. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a first 5G/NR frame, DL channels within a 5G/NR subframe, a second 5G/NR frame, and UL channels within a 5G/NR subframe, respectively.

FIG. 3 is a diagram illustrating an example of a base station and user equipment (UE) in an access network.

FIG. 4 is a diagram illustrating a UE communicating with a base station in a mobile communication network.

FIG. 5 is a communication diagram illustrating a UE downgrading to a secondary RAT for communication with a base station.

FIG. 6 is a flowchart of a method of wireless communication.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements” ) . These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs) , central processing units (CPUs) , application processors, digital signal processors (DSPs) , reduced instruction set computing (RISC) processors, systems on a chip (SoC) , baseband processors, field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM) , a read-only memory (ROM) , an electrically erasable programmable ROM (EEPROM) , optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

FIG. 1 is a diagram illustrating an example of a wireless communications system and an access network 100. The wireless communications system (also referred to as a wireless wide area network (WWAN) ) includes base stations 102, UEs 104, an Evolved Packet Core (EPC) 160, and another core network 190 (e.g., a 5G Core (5GC) ) . The base stations 102 may include macrocells (high power cellular base station) and/or small cells (low power cellular base station) . The macrocells include base stations. The small cells include femtocells, picocells, and microcells.

The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN) ) may interface with the EPC 160 through first backhaul links 132 (e.g., S1 interface) . The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN) ) may interface with core network 190 through second backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity) , inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS) , subscriber and equipment trace, RAN information management (RIM) , paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or core network 190) with each other over third backhaul links 134 (e.g., X2 interface) . The third backhaul links 134 may be wired or wireless.

The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102' may have a coverage area 110' that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macrocells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs) , which may provide service to a restricted group known as a closed subscriber group (CSG) . The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations 102 /UEs 104 may use spectrum up to Y MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL than for UL) . The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell) .

Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH) , a physical sidelink discovery channel (PSDCH) , a physical sidelink shared channel (PSSCH) , and a physical sidelink control channel (PSCCH) . D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs 152 /AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.

The small cell 102' may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP 150. The small cell 102', employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network.

A base station 102, whether a small cell 102' or a large cell (e.g., macro base station) , may include and/or be referred to as an eNB, gNodeB (gNB) , or another type of base station. Some base stations, such as gNB 180 may operate in a traditional sub 6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW /near mmW radio frequency band (e.g., 3 GHz –300 GHz) has extremely high path loss and a short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range. The base station 180 and the UE 104 may each include a plurality of antennas, such as antenna elements, antenna panels, and/or antenna arrays to facilitate the beamforming.

The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182'. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182”. The UE 104 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180 /UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180 /UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.

The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN) , and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network 190 may include a Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the core network 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS) , a PS Streaming Service, and/or other IP services.

The base station may include and/or be referred to as a gNB, Node B, eNB, an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , a transmit reception point (TRP) , or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or core network 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA) , a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player) , a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc. ) . The UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

Referring again to FIG. 1, in certain aspects, the UE 104 may be configured to downgrade from a primary RAT to a secondary RAT (198) . Although the following description may be focused on downgrading from 5G to 4G, the concepts described herein may be applicable to other similar areas, such as transitioning between any other two RATs (or other communication protocols) , such as LTE, LTE-A, CDMA, GSM, and other wireless technologies. In some aspects, the concepts described herein may be applicable from downgrading from a future RAT (e.g., 6G) to a previous generation RAT (e.g., 5G, 4G, etc. )

FIG. 2A is a diagram 200 illustrating an example of a first subframe within a 5G/NR frame structure. FIG. 2B is a diagram 230 illustrating an example of DL channels within a 5G/NR subframe. FIG. 2C is a diagram 250 illustrating an example of a second subframe within a 5G/NR frame structure. FIG. 2D is a diagram 280 illustrating an example of UL channels within a 5G/NR subframe. The 5G/NR frame structure may be FDD in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for either DL or UL, or may be TDD in which for a particular set of subcarriers (carrier system bandwidth) , subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by FIGs. 2A, 2C, the 5G/NR frame structure is assumed to be TDD, with subframe 4 being configured with slot format 28 (with mostly DL) , where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe 3 being configured with slot format 34 (with mostly UL) . While

subframes

3, 4 are shown with slot formats 34, 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0, 1 are all DL, UL, respectively. Other slot formats 2-61 include a mix of DL, UL, and flexible symbols. UEs are configured with the slot format (dynamically through DL control information (DCI) , or semi-statically/statically through radio resource control (RRC) signaling) through a received slot format indicator (SFI) . Note that the description infra applies also to a 5G/NR frame structure that is TDD.

Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms) . Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission) . The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2 ^μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2 ^μ*15 kHz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing. FIGs. 2A-2D provide an example of slot configuration 0 with 14 symbols per slot and numerology μ=2 with 4 slots per subframe. The slot duration is 0.25 ms, the subcarrier spacing is 60 kHz, and the symbol duration is approximately 16.67 μs.

A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs) ) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs) . The number of bits carried by each RE depends on the modulation scheme.

As illustrated in FIG. 2A, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include demodulation RS (DM-RS) (indicated as R _x for one particular configuration, where 100x is the port number, but other DM-RS configurations are possible) and channel state information reference signals (CSI-RS) for channel estimation at the UE. The RS may also include beam measurement RS (BRS) , beam refinement RS (BRRS) , and phase tracking RS (PT-RS) .

FIG. 2B illustrates an example of various DL channels within a subframe of a frame. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs) , each CCE including nine RE groups (REGs) , each REG including four consecutive REs in an OFDM symbol. A primary synchronization signal (PSS) may be within symbol 2 of particular subframes of a frame. The PSS is used by a UE 104 to determine subframe/symbol timing and a physical layer identity. A secondary synchronization signal (SSS) may be within symbol 4 of particular subframes of a frame. The SSS is used by a UE to determine a physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine a physical cell identifier (PCI) . Based on the PCI, the UE can determine the locations of the aforementioned DM-RS. The physical broadcast channel (PBCH) , which carries a master information block (MIB) , may be logically grouped with the PSS and SSS to form a synchronization signal (SS) /PBCH block. The MIB provides a number of RBs in the system bandwidth and a system frame number (SFN) . The physical downlink shared channel (PDSCH) carries user data, broadcast system information not transmitted through the PBCH such as system information blocks (SIBs) , and paging messages.

As illustrated in FIG. 2C, some of the REs carry DM-RS (indicated as R for one particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may transmit DM-RS for the physical uplink control channel (PUCCH) and DM-RS for the physical uplink shared channel (PUSCH) . The PUSCH DM-RS may be transmitted in the first one or two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether short or long PUCCHs are transmitted and depending on the particular PUCCH format used. The UE may transmit sounding reference signals (SRS) . The SRS may be transmitted in the last symbol of a subframe. The SRS may have a comb structure, and a UE may transmit SRS on one of the combs. The SRS may be used by a base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

FIG. 2D illustrates an example of various UL channels within a subframe of a frame. The PUCCH may be located as indicated in one configuration. The PUCCH carries uplink control information (UCI) , such as scheduling requests, a channel quality indicator (CQI) , a precoding matrix indicator (PMI) , a rank indicator (RI) , and HARQ ACK/NACK feedback. The PUSCH carries data, and may additionally be used to carry a buffer status report (BSR) , a power headroom report (PHR) , and/or UCI.

FIG. 3 is a block diagram of a base station 310 in communication with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to a controller/processor 375. The controller/processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller/processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIBs) , RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release) , inter radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression /decompression, security (ciphering, deciphering, integrity protection, integrity verification) , and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs) , error correction through ARQ, concatenation, segmentation, and reassembly of RLC service data units (SDUs) , re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs) , demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK) , quadrature phase-shift keying (QPSK) , M-phase-shift keying (M-PSK) , M-quadrature amplitude modulation (M-QAM) ) . The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT) . The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.

The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression /decompression, and security (ciphering, deciphering, integrity protection, integrity verification) ; RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.

At least one of the TX processor 368, the RX processor 356, and the controller/processor 359 may be configured to perform aspects in connection with 198 of FIG. 1.

FIG. 4 is a diagram 400 illustrating a UE 402 communicating with a base station 404 in a mobile communication network. The UE 402 may be configured to operate utilizing a primary RAT (e.g., 5G) and may also be configured to operate utilizing a secondary RAT (e.g., 4G) . The base station 404 may also be configured to operate utilizing the primary RAT (e.g., 5G) and may also be configured to operate utilizing the secondary RAT (e.g., 4G) . The UE 402 may include data or files that are related to the primary RAT, but that are not related to the secondary RAT. For example, the UE 402 may include a subscription permanent identifier (SUPI) or a subscription concealed identifier (SUCI) . The SUPI may be a unique identifier for the UE 402. The SUCI may be the SUPI encoded based on a scheme configured for the mobile communication network, and may be transmitted to the base station 404 to allow the base station 404 to determine the SUPI for the UE 402 without transmitting the unprotected SUPI.

In some aspects, as shown at 408, the primary RAT may only be partially deployed for the mobile communication network. For example, a mobile network operator may be upgrading the mobile communication network from 4G to 5G, but the mobile communication network may only be partially upgraded. The mobile network operator may be limited by the capital or operational expenditures associated with upgrading and/or maintaining the mobile communication network on the primary RAT. The mobile communication network may be upgraded for the primary RAT but not fully configured. For example, the mobile communication network may be upgraded to 5G, but non-NULL SUCI protection schemes (e.g., Scheme A, Scheme B, proprietary Scheme) may not be implemented. Additionally or alternatively, in some aspects, the mobile communication network may have poor coverage for the primary RAT.

A UE communicating with a base station utilizing a primary RAT where the primary RAT is only partially deployed for the mobile communication network may present security risks. For example, where the mobile communication network is not configured with any non-NULL SUCI protection schemes, a UE transmitting a SUCI based on the NULL protection scheme may expose the SUPI of the UE over the air. Further, where the primary RAT is only partially deployed for the mobile communication network in a region, the UE may have poor network coverage for the primary RAT in that region resulting in poor service, and frequent switching between the primary RAT and the secondary RAT may consume power from the battery of the UE.

In some aspects, even where the primary RAT is fully deployed for the mobile communication network, a UE may have a problematic file configuration for the primary RAT. For example, files for the primary RAT (e.g., files of a 5G subscriber identity module (SIM) card) may have been configured prior to a change in a standard associated with the primary RAT, resulting in the UE having incomplete information for the primary RAT.

In some aspects, as illustrated at 406, the UE 402 may be configured to downgrade to the secondary RAT. The UE 402 may be configured to determine when it is communicating with the mobile communication network (e.g., the base station 404) that is partially deployed for the primary RAT, may be configured to determine when it is communication with the mobile communication network with poor coverage for the primary RAT, and/or may be configured to determine when it has a problematic file configuration for the primary RAT. The UE 402 may then communicate with the mobile communication network (e.g., the base station 404) utilizing the secondary RAT (e.g., may camp on the secondary RAT) . In some aspects, the UE 402 may not access data or files of the UE 402 associated with the primary RAT (e.g., the SUPI or the SUCI) and may block access to the files associated with the primary RAT.

FIG. 5 is a communication diagram 500 illustrating a UE 502 downgrading to a secondary RAT for communication with a base station 504. The UE 502 may be the UE 402 described above, and the base station 504 may be the base station 404 described above. The UE 502 and the base station 504 may be part of the same mobile communication network.

As illustrated at 506, the UE 502 may determine that a trigger has occurred. Occurrence of the trigger may indicate that the primary RAT should not be utilized. For example, occurrence of the trigger may indicate that the primary RAT is not fully deployed on the mobile communication network, may indicate that the mobile communication network has poor coverage for the primary RAT, and/or may indicate that the UE 502 has a problematic file configuration for the primary RAT.

In some aspects, the UE 502 may determine whether the trigger has occurred when the UE 502 powers up. In some aspects, the UE 502 may determine whether the trigger has occurred when a universal integrated circuit card (UICC) (e.g., a SIM card) hotswap has occurred. In some aspects, the UE 502 may determine whether the trigger has occurred when APM is turned on or turned off. In some aspects, the UE 502 may determine whether the trigger has occurred upon receiving a trigger over the air.

In some aspects, the trigger may be matching an identifier for the mobile communication network to a value in a list of identifiers. The UE 502 may be configured with a list of identifiers of mobile communication networks for which the primary RAT should not be utilized. For example, the UE 502 may be configured with a mobile country code (MCC) and/or a mobile network code (MNC) . The UE 502 may read the MCC and/or the MNC from a SIM card of the UE 502. The MCC, the MNC, or the combination of the MCC and the MNC may be the identifier, and may be compared to a list of MCCs and/or MNCs of mobile communication networks for which the primary RAT should not be utilized.

In some aspects, the list of identifiers may be preconfigured on the UE 502. In some aspects, the base station 504 may transmit an identifier list configuration message 510 to the UE 502. The identifier list configuration message 510 may configure or may be re-configure the list of identifiers. The UE 502 may receive the identifier list configuration message 510 and may update or replace its list of identifiers based on the message. In some aspects, the UE 502 may determine whether the trigger has occurred when the list of identifiers is configured or reconfigured.

In some aspects, a database 511 may include the list of identifiers. The database 511 may be a cloud database, such as one maintained by the original equipment manufacturer of the UE 502. The UE 502 may communicate with the database 511 to configure or reconfigure the list of identifiers on the UE 502. In some aspects, the database 511 may transmit the list of identifiers 512 to the UE 502. In some aspects, the UE 502 may determine whether the identifier for the mobile communication network matches a value stored on the list of identifiers on the database by transmitting the identifier for the mobile communication network to the database 511 and receiving a response from the database 511 (e.g., instead of retaining the list of identifiers at the UE 502) . In some aspects, the UE 502 may determine whether the trigger has occurred when the list of identifiers is configured or reconfigured.

In some aspects, the trigger may be matching a geographic identifier indicating a current geographic region where the UE is located to a value in a list of geographic identifiers where the primary RAT should not be utilized (e.g., a geographic region with poor coverage for the primary RAT) . The geographic identifier may be a location area identity or a tracking area identity. The list of geographic identifiers may be preconfigured or may be dynamically configured as described above with respect to the list of identifiers of mobile communication networks described above. In some aspects, the list of geographic identifiers may be dynamically configured utilizing firmware over-the-air (FOTA) .

In some aspects, the trigger may be based on operator deployment or security. For example, where the calculation of the SUCI based on the SUPI is performed at the UE 502, the trigger may be determining that the SUCI calculation is performed based on a NULL protection scheme. In some aspects, the trigger may be determining that the UE 502 has incomplete files, or that the mobile communication network is partially deployed for the primary RAT.

In some aspects, the trigger may be any combination of the above. For example, in some aspects, the trigger may be determining that a network identifier (e.g., an MCC and/or an MNC) of the UE 502 is present in a list of network identifiers and determining that a geographic identifier is present in a list of geographic identifiers for that network identifier, indicating that the primary RAT should not be utilized in the current geographic region of the UE 502 for the mobile communication network of the UE 502.

In some aspects, as illustrated at 507, upon determining that the trigger has occurred, the UE 502 may disable access to data or files related to the primary RAT (e.g., may disable read access for files associated with the primary RAT) . For example, where the primary RAT is 5G and the secondary RAT is 4G, the UE 502 may disable read access to the SUPI and/or SUCI.

Upon determining that the trigger has occurred, as illustrated at 508, the UE 502 may enter into an RRC connected state with the base station 504 utilizing the secondary RAT (e.g., may camp on the secondary RAT) . In some aspects, the UE 502 may not access data or files associated with the primary RAT when entering into the RRC connected state with the base station 504. For example, where the primary RAT is 5G and the secondary RAT is 4G, the UE 502 may not access the SUPI and/or SUCI.

In some aspects, the UE 502 may perform a proactive refresh with Reset mode to reset the UE 502 to camp to the secondary RAT (e.g., may send a refresh message with a reset mode to allow the UE 502 to enter the RRC connected state utilizing the secondary RAT) . For example, a typical refresh may involve a refresh message may be sent from the SIM card of the UE 502 to a processor of the UE 502 (e.g., controller/processor 359 described with respect to FIG. 3) indicating that the UE 502 should refresh the SIM card data, and the UE 502 may read the data contained on the SIM card (e.g., and store the data on memory 360) . Here, the UE 502 may send a proactive refresh message to itself, may reset the SIM card, and may limit the UE’s capabilities for the primary RAT on the next SIM card power up to support utilizing the secondary RAT. For example, where the primary RAT is 5G and the secondary RAT is 4G, the bits in the terminal profile related to support for 5G may be set to zero, and the 5G elementary files may not be read from the 5G enabled SIM card.

FIG. 6 is a flowchart 600 of a method of wireless communication. method may be performed by a UE (e.g., the

UE

350, 402, 502, which may include the memory 360 and which may be the entire UE or a component of the UE, such as the TX processor 368, the RX processor 356, and/or the controller/processor 359) .

At 602, the UE determines that a trigger has occurred. The trigger indicates that a primary RAT should not be utilized. The UE may include a subscriber identification module (SIM) card, and determining that the trigger has occurred may include reading a mobile country code and a mobile network code from the SIM card and determining if the mobile country code and mobile network code are present in a configured set of mobile country codes and mobile network codes. Determining that the trigger has occurred may include determining that a SUCI for the UE will be calculated based on a NULL protection scheme, Determining that the trigger has occurred may include determining a geographic identifier indicating a current geographic region where the UE is located and determining if the geographic identifier is present in a configured set of geographic identifiers. The UE may include a SIM card, and determining that the trigger has occurred may include determining that the SIM card contains incomplete files for the primary RAT.

At 604, upon determining at 602 that the trigger has occurred, the UE enters into an RRC connected state with a base station utilizing a secondary RAT. The UE may enter into the RRC connected state without accessing data related to the primary RAT. The primary RAT may be 5G and the secondary RAT may be a pre-5G RAT (e.g., 4G) . The data related to the primary RAT may be a subscription permanent identifier or a subscription concealed identifier.

At 606, upon determining at 602 that the trigger has not occurred, the UE enters into an RRC connected state with the base station utilizing the primary RAT.

Further disclosure is included in the Appendix.

It is understood that the specific order or hierarchy of blocks in the processes /flowcharts disclosed is an illustration of example approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes /flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C, ” “one or more of A, B, or C, ” “at least one of A, B, and C, ” “one or more of A, B, and C, ” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module, ” “mechanism, ” “element, ” “device, ” and the like may not be a substitute for the word “means. ” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for. ”

Claims

A method of wireless communication at a user equipment (UE) , comprising:

determining whether a trigger has occurred, the trigger indicating that a primary radio access technology should not be utilized;

entering into an RRC connected state with a base station utilizing a secondary radio access technology without accessing data related to the primary radio access technology upon determining that the trigger has occurred; and

entering into an RRC connected state with the base station utilizing the primary radio access technology upon determining that the trigger event has not occurred.
The method of claim 1, wherein the primary radio access technology is 5G and the secondary radio access technology is a pre-5G radio access technology.
The method of claim 1, wherein the UE comprises a subscriber identification module (SIM) card, and wherein determining that the trigger has occurred comprises reading a mobile country code and a mobile network code from the SIM card and determining if the mobile country code and mobile network code are present in a configured set of mobile country codes and mobile network codes.
The method of claim 1, wherein determining that the trigger has occurred comprises determining that a subscription concealed identifier for the UE will be calculated based on a NULL protection scheme.
The method of claim 1, wherein determining that the trigger has occurred comprises determining a geographic identifier indicating a current geographic region where the UE is located and determining if the geographic identifier is present in a configured set of geographic identifiers.
The method of claim 1, wherein the UE comprises a subscriber identification module (SIM) card, and wherein determining that the trigger has occurred comprises determining that the SIM card contains incomplete files for the primary radio access technology.
The method of claim 1, wherein the data related to the primary radio access technology is a subscription permanent identifier or a subscription concealed identifier.
The method of claim 1, wherein the UE does not does not access the base station utilizing the primary radio access technology upon determining that the trigger event has occurred.