Backoff mechanism for transmitting data over the control plane

Abstract

The various techniques and methods described herein may be applied to control congestion at a session management (SM) function (SMF) based on at least one backoff timer maintained at a user equipment (UE). In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE may be configured to establish a protocol data unit (PDU) session with the SMF. The UE may be configured to determine whether a backoff timer associated with the PDU session has expired. When the backoff timer has not expired, the UE may suppress sending data to the SMF via a control plane associated with the PDU session. When the backoff timer expires, the UE may send the data to the SMF via a control plane associated with the PDU session.

Description

background Technical Field

[0002] The present disclosure relates generally to communication systems, and more particularly to user equipment configured to transmit data over a control plane.

[0003] introduction

[0004] Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcast. 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.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide common protocols that enable different wireless devices to communicate at city, country, region, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is a part of the continuous mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5GNR includes services associated with enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). Some aspects of 5G NR can be based on 4G Long Term Evolution (LTE) standards. There is a need for further improvements to 5G NR technology. These improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies.

[0006] Overview

[0007] A brief summary of one or more aspects is given below to provide a basic understanding of such aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define 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 a more detailed description that will be presented later.

[0008] Various techniques and approaches described herein may be used to control congestion at a session management (SM) function (SMF) based on at least one back-off timer maintained at a user equipment (UE).

[0009] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE may be configured to establish a protocol data unit (PDU) session with an SMF. The UE may be configured to determine whether a backoff timer associated with the PDU session has expired. When the backoff timer has not expired, the UE may suppress sending data to the SMF via a control plane associated with the PDU session. When the backoff timer expires, the UE may send the data to the SMF via a control plane associated with the PDU session.

[0010] In another aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be an access and mobility management function (AMF). The AMF may receive a mobility management (MM) message from a UE, and the MM message may include data through a control plane associated with a PDU session established between the UE and an SMF. The AMF may determine whether the UE is allowed or prohibited from sending data to the SMF through the control plane for the PDU session. When the UE is prohibited from sending data to the SMF, the AMF may send a message including the duration of a backoff timer to the UE. When the UE is allowed to send the data to the SMF through the control plane, the AMF may send the data to the SMF through the control plane.

[0011] To achieve the foregoing and related ends, the one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and drawings set forth in detail certain illustrative features of the one or more aspects. However, these features are merely indicative of several of the various ways in which the principles of the various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0014] Figure 2A , 2B , 2C, and 2D are diagrams illustrating examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0015] Figure 3 is a diagram illustrating an example of a base station and a user equipment (UE) in an access network.

[0016] Figure 4 is a call flow diagram illustrating a wireless communication system.

[0017] Figure 5 is a flow chart of a wireless communication method.

[0018] Figure 6 is a flow chart of a wireless communication method.

[0019] Detailed Description

[0020] The detailed description set forth below in conjunction with the accompanying 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. This detailed description includes specific details to provide a thorough understanding of the 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 diluting such concepts.

[0021] 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 on the specific application and the design constraints imposed on the overall system.

[0022] As an example, an element, or any part of an element, or any combination of elements may be implemented as a "processing system" including 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 chip (SoCs), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gating logic, discrete hardware circuits, and other suitable hardware configured to perform various functionalities described throughout this disclosure. One or more processors in a processing system may execute software. Software should be broadly interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether it is described in software, firmware, middleware, microcode, hardware description languages, or other terms.

[0023] Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, each function may be stored or encoded on a computer-readable medium as one or more instructions or codes. Computer-readable media include computer storage media. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, a combination of computer-readable media of the above types, 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.

[0024] Figure 1 1 is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0025] 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 EPC 160 via a backhaul link 132 (e.g., an S1 interface). Base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with core network 190 via a backhaul link 184. Base stations 102 may perform one or more of the following functions, among other functions: delivery of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (eg, through the EPC 160 or the core network 190) via a backhaul link 134 (eg, an X2 interface). The backhaul link 134 may be wired or wireless.

[0026] Base stations 102 may communicate wirelessly with UEs 104. Each base station 102 may provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. A heterogeneous network may also include a home evolved Node B (eNB) (HeNB), which may provide services to a restricted group called a closed subscriber group (CSG). A communication link 120 between a base station 102 and a UE 104 may include an uplink (UL) (also known as a reverse link) transmission from the UE 104 to the base station 102 and / or a downlink (DL) (also known as a forward link) transmission from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may be over one or more carriers. The base station 102 / UE 104 may use spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.) bandwidth for each carrier allocated in a carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0027] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use 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). The D2D communication may be through a variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0028] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 in the 5 GHz unlicensed spectrum via a communication link 154. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether the channel is available prior to communication.

[0029] The small cell 102' may operate in a licensed and / or unlicensed spectrum. When operating in an unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum as used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may boost the coverage of the access network and / or increase the capacity of the access network.

[0030] Whether a small cell 102' or a large cell (e.g., a macro base station), the base station 102 may include an eNB, a gB node (gNB), or another type of base station. Some base stations (such as gNB 180) may operate in traditional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When gNB 180 operates in mmW or near mmW frequencies, gNB 180 may be referred to as a 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 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW can be extended down to 3 GHz frequencies with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands (e.g., 3 GHz–300 GHz) have extremely high path loss and 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.

[0031] Base station 180 may transmit beamformed signals to UE 104 in one or more transmit directions 182'. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182". UE 104 may also transmit beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may be the same or may be different. The transmit direction and receive direction of UE 104 may be the same or may be different.

[0032] The EPC 160 may include a mobility management (MM) 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 a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to 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 functionality for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmissions, 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 base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related charging information.

[0033] The core network 190 may include an 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 a control node that handles signaling between the UE 104 and the core network 190. In general, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are delivered through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0034] A base station may also be referred to as a gNB, a Node B, an evolved 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 transmission reception point (TRP), or some other suitable term. The base station 102 provides an access point to the EPC 160 or the core network 190 for the UE 104. Examples of UE 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., an MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a health care device, an implant, a sensor / actuator, a display, or any other similar functional device. Some UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, ovens, vehicles, heart monitors, etc.). 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 communication 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.

[0035] Although the present disclosure may refer to 5G New Radio (NR), the present disclosure may be applicable to other similar areas such as LTE, Advanced LTE (LTE-A), Code Division Multiple Access (CDMA), Global System for Mobile Communications (GSM), or other wireless / radio access technologies.

[0036] Refer again Figure 1 In certain aspects, the UE 104 and / or the AMF 192 may be configured to implement congestion control (198) for the SMF 194 based on one or more backoff timers maintained at the UE 104 and / or the AMF 192.

[0037] Figure 2A 200 is a diagram illustrating an example of a first subframe within a 5G / NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G / NR subframe. Figure 2C 250 is a diagram illustrating an example of a second subframe within a 5G / NR frame structure. Figure 2D280 is a diagram illustrating an example of an UL channel within a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , 2C In the example provided, the 5G / NR frame structure is assumed to be TDD, where subframe 4 is configured with slot format 28 (mostly DL) and subframe 3 is configured with slot format 34 (mostly UL), where D is DL, U is UL, and X is for flexible use between DL / UL. Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0-61. Slot formats 0 and 1 are full DL and full UL, respectively. Other slot formats 2-61 include a mixture of DL, UL, and flexible symbols. The UE is configured with a slot format (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling) through the received slot format indicator (SFI). Note that the following description also applies to the 5G / NR frame structure for TDD.

[0038] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 equally sized subframes (1ms). Each subframe may include one or more time slots. A subframe may also include mini-slots, which may include 7, 4, or 2 symbols. Each time slot may include 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also known as single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots within a subframe is based on the time slot configuration and parameter design. For slot configuration 0, different parameter designs μ of 0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter designs 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Accordingly, for slot configuration 0 and parameter design μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration vary depending on parameter design. The subcarrier spacing can be equal to 2 μ*15kHz, where μ is parameter design 0 to 5. Thus, parameter design μ=0 has a subcarrier spacing of 15kHz, while parameter design μ=5 has a subcarrier spacing of 480kHz. The symbol length / duration is inversely related to the subcarrier spacing. Figures 2A-2D An example of slot configuration 0 with 14 symbols per slot and parameter design μ=0 is provided, with 1 slot per subframe. The subcarrier spacing is 15 kHz and the symbol duration is about 66.7 μs.

[0039] A resource grid may be used to represent the frame structure. Each slot includes a resource block (RB) (also called a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a number of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0040] like Figure 2A As explained in the illustration, some REs carry reference (pilot) signals (RS) for UEs. RSs may include demodulation RSs (DM-RSs) for channel estimation at the UE (indicated as R for a particular configuration). x , where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0041] Figure 2B An example of various DL channels within a subframe of a frame is illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including 9 RE groups (REGs), each REG including 4 consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) may be within symbol 2 of a particular subframe of a frame. The PSS is used by the UE 104 to determine the subframe / symbol timing and the physical layer identity. The secondary synchronization signal (SSS) may be within symbol 4 of a particular subframe of a frame. The SSS is used by the UE to determine the physical layer cell identity group number and the radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE may determine the physical cell identifier (PCI). Based on the PCI, the UE may determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) may be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the number of RBs in the system bandwidth, as well as the 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.

[0042] As in Figure 2CAs illustrated in FIG, some REs carry DM-RSs for channel estimation at the base station (indicated as R for one particular configuration, but other DM-RS configurations are possible). The UE may transmit DM-RSs for the physical uplink control channel (PUCCH) and DM-RSs for the physical uplink shared channel (PUSCH). The PUSCH DM-RS may be transmitted in the first or first two symbols of the PUSCH. The PUCCH DM-RS may be transmitted in different configurations depending on whether a short PUCCH or a long PUCCH is transmitted and on the specific PUCCH format used. Although not shown, the UE may transmit a sounding reference signal (SRS). The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

[0043] Figure 2D An example of various UL channels within a subframe of an illustration frame. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), 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.

[0044] Figure 33 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 media access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), 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 of UE measurement reports; PDCP layer functionality associated with header compression / decompression, security (ciphering, cipher decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery 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.

[0045] The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, including the physical (PHY) layer, may include error detection on the transport channel, forward error correction (FEC) encoding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation 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 domain 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 generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine coding and modulation schemes and for spatial processing. The channel estimates may be derived from reference signals 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 corresponding spatial stream for transmission.

[0046] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a 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 can perform spatial processing on the information to recover any spatial stream destined for the UE 350. If there are multiple spatial streams destined for the UE 350, they can be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then transforms the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the signal constellation point most likely transmitted by the base station 310. These soft decisions can be based on the channel estimates calculated by the channel estimator 358. These soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by the base station 310. These data and control signals are then provided to the controller / processor 359 which implements layer 3 and layer 2 functionality.

[0047] The controller / processor 359 may 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 channels and logical channels, packet reassembly, cipher interpretation, 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 ACK and / or NACK protocols to support HARQ operations.

[0048] Similar to the functionality described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression, and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing MAC SDUs onto TBs, demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0049] Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by a 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 antennas 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0050] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality 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.

[0051] The controller / processor 375 may 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 channels and logical channels, packet reassembly, cipher decoding, header decompression, control signal processing to recover IP packets from the UE 350. The 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 ACK and / or NACK protocols to support HARQ operations.

[0052] In some systems, the AMF may be configured to apply congestion control to the SMF, such as 5GSM congestion control in a 5G system (5GS). For example, congestion control may be applied at a slice level, a data network name (DNN) level, or both a slice and a DNN level. When congestion control is applied to the SMF, the AMF may send a DL NAS transport message to the UE including a session management (SM) message (e.g., a 5GSM message) received from the UE and further including the duration of the backoff timer, as described in the present disclosure.

[0053] Illustratively, upon receiving a UL NAS transport message, if the payload container type information element (IE) is set to "N1 SM information": the request type IE is set to "initial request" or "existing PDU session"; or the request type IE is set to "modify request" and the PDU session is not an emergency PDU session; the UE is not configured for high priority access in the selected PLMN, and one of the following (a), (b) and (c) is true: (a) DNN-based congestion control may be activated for the DNN included in the UL NAS transport message, or DNN-based congestion control may be activated for the selected DNN in the case where the DNN is not included in the UL NAS transport message (e.g., configured by operation and maintenance), then the AMF may be configured to send back to the UE an unforwarded 5GSM message, a backoff timer value, and a reason indicating "congestion" (e.g., 5GMM reason code #22); (b) congestion control based on single network slice selection assistance information (S-NSSAI) and DNN may be activated for the UL (c) if the S-NSSAI and DNN included in the NAS transmission message are activated, or in the case where the DNN is not included in the UL NAS transmission message, congestion control based on S-NSSAI and DNN may be activated for the S-NSSAI and the selected DNN included in the UL NAS transmission message, or in the case where the S-NSSAI is not included in the UL NAS transmission message and the DNN is included in the UL NAS transmission message, congestion control based on S-NSSAI and DNN is activated for the selected S-NSSAI, or in the case where the S-NSSAI and DNN are not included in the UL NAS transmission message, congestion control based on S-NSSAI and DNN is activated for the selected S-NSSAI and the selected DNN (for example, configured by operation and maintenance), the AMF may send back to the UE a 5GSM message that is not forwarded, a backoff timer value, and a reason indicating "insufficient resources for a specific slice and DNN" (for example, 5GMM reason code #67); or (c) congestion control based only on S-NSSAI may be activated for the UL If the S-NSSAI included in the NAS transport message is activated, or if S-NSSAI-based congestion control is activated for the selected S-NSSAI in the case where the S-NSSAI is not included in the UL NAS transport message (e.g., configured by operation and maintenance), the AMF may send back to the UE a non-forwarded 5GSM message, the backoff timer value, and a reason indicating "insufficient resources for a specific slice" (e.g., 5GMM reason code #69).

[0054] When the UE receives a DL NAS transport message including a backoff timer IE, the UE may pass information indicating that the 5GSM message was not forwarded due to congestion control together with the 5GSM message and the time value from the backoff timer value IE to the 5GSM layer. In response, the UE may start a 5GSM backoff timer and refrain from sending mobile originated (MO) 5GSM signaling until the backoff timer expires or until a 5GSM message terminating the backoff timer is received.

[0055] In some other aspects, the SMF may also apply congestion control directly to the UE's 5GSM layer by including a backoff timer in a 5GSM message sent to the UE. For example, a PDU Session Modification Reject message may include a backoff timer value IE, which may be applied by the UE to the 5GSM layer of the UE. The 5GSM layer of the UE may be configured to operate similarly to the manner described herein with respect to the application of congestion control by the AMF.

[0056] In an overload condition, the AMF may limit requests from the UE for data transmission via control plane Cellular Internet of Things (CIoT) 5GS optimization. A control plane data backoff timer (e.g., timer T3448 in 5GS) may be returned to the UE by the AMF (e.g., in a registration accept message, a service reject message, and / or a service accept message). When the aforementioned control plane data backoff timer is running, the UE may suppress the initiation of any data transmission via control plane CIoT 5GS optimization (e.g., the UE may suppress sending any initial NAS message with uplink data). The AMF may store a corresponding control plane data backoff timer for each UE, and when the corresponding control plane data backoff timer for the UE is running, the AMF may suppress processing any further requests for data transmission via initial NAS messages from the UE (e.g., except for exception reports and paging responses).

[0057] In some further aspects, the concept of "service gap" may be defined for some systems (e.g., 5G CIoT), which may use a service gap timer to control the frequency of transitioning from an idle mode (e.g., 5GMM idle mode) to a connected mode (e.g., 5GMM connected mode). The UE and the network (e.g., 5G RAN) in which the UE is operating may negotiate the use of service gap control (SGC), based on which the network may provide a service gap timer (e.g., timer T3447 in 5G) to the UE. While the service gap timer is running, the UE may be allowed by the network to: (1) request emergency services; (2) request emergency fallback; (3) request high priority access; (4) perform registration procedures for initial registration; (5) perform registration procedures for mobility and periodic registration updates without including an UL data status IE; and / or (6) send a mobile terminated service request triggered by paging and subsequent MO signaling or MO data (if any) until the UE enters an idle mode (e.g., 5GMM idle mode).

[0058] Not all UEs support SGC. However, the network may apply SGC for these UEs based on the subscription information associated with these UEs. For example, when a UE that does not support SGC sends a 5GSM message: upon receiving a UL NAS transport message, if the payload container type IE is set to "N1 SM information": the request type IE is set to "initial request" or "existing PDU session"; or the request type IE is set to "modify request" and the PDU session is not an emergency PDU session; the UE is not configured for high priority access in the selected PLMN, and the service gap timer (e.g., timer T3447) is running and the UE does not support SGC: (1) the current NAS signaling connection is not triggered by paging; and (2) mobile terminated signaling has not been sent over the current NAS signaling connection, then the AMF may send a message back to the UE that was not forwarded, send information indicating the "congestion" reason (e.g., 5GMM reason code #22), and may include a backoff timer set to the remaining time of the service gap timer maintained for the UE at the network (e.g., AMF).

[0059] Various protocols (e.g., 5G CIoT) support data transmission over the control plane, which may also be referred to as data over NAS. When sending data over the control plane from an idle mode (e.g., 5GMM idle mode), the UE may send a control plane service request (CPSR) message including the data, and when the data is not short message service (SMS) data, may send a PDU session identifier (ID) associated with the PDU session for which the data is being sent. The AMF may forward the data and the PDU session ID to the SMF associated with the PDU session. When sending data over the control plane from a connected mode (e.g., 5GMM connected mode), the UE may use a different message (e.g., UL NAS transport message), but each message from a UE in connected mode may include data and a PDU session ID.

[0060] The aforementioned congestion control (e.g., 5GSM congestion control) may not restrict the sending of data for a PDU session through the control plane at an already congested SMF. When congestion control is applied for 5GSM (such as at the 5GMM layer and / or 5GSM layer of the UE), the UE may only be restricted from sending 5GSM messages - that is, the UE may suppress the sending of 5GSM signaling when the backoff timer is running. However, limiting only the UE's 5GSM signaling may allow the UE to continue to send data through the control plane for the same PDU session that has indicated SMF congestion (therefore limiting 5GSM signaling). When sending data through the control plane to an already congested SMF (e.g., as indicated by the restriction on 5GSM signaling), the UE may increase the congestion experienced by the SMF. Accordingly, the present disclosure may describe various techniques and methods for limiting the transmission of data through the control plane to a congested SMF.

[0061] In addition, the SMF may be separated from the AMF, and therefore congestion at one SMF does not necessarily mean that another SMF is also congested. If congestion control for the aforementioned user plane transmission is used due to congestion of one SMF, a UE having another PDU session (e.g., potentially established through a different SMF) will be restricted from sending any data (e.g., to other SMFs) for the other PDU session because the control plane data backoff timer (e.g., timer T3448 in 5GS) restricts the UE for all PDU sessions (e.g., at the UE's 5GMM layer). Therefore, the present disclosure may describe various techniques and methods for restricting data transmission through the control plane to a congested SMF while allowing the UE to send data through the control plane for another PDU session served by another non-congested SMF.

[0062] In addition, as described above with respect to SGC, when the AMF receives a 5GSM message from a UE that does not support SGC but the service gap timer for the UE (e.g., timer T3447 in 5GS) is running at the AMF, the AMF may send the 5GSM message and the backoff timer to the UE in the DL NAS transport message. However, the AMF may lack a similar mechanism to handle the reception of UL NAS transport messages for UEs that do not support SGC. Accordingly, the present disclosure may describe various techniques and methods for handling the reception of data from a UE by the AMF through the control plane, the UE does not support SGC and the service gap timer for the UE (e.g., timer T3447 in 5GS) is running at the AMF. Similarly, the present disclosure may describe various techniques and methods for a UE that does support SGC to still transmit UL NAS transport messages and data, because the service gap timer for a UE such as may only limit 5GSM messages.

[0063] Figure 4 4 is a call flow diagram of a wireless communication system 400. The wireless communication system 400 may include a UE 406 (eg, UE 104, UE 350), and may further include an AMF 404 (eg, AMF 192, other AMF 193) and an SMF 402 (eg, SMF 194).

[0064] The UE 406 may include multiple layers, including at least an SM layer 408b (e.g., a 5GSM layer) and an MM layer 408a (e.g., a 5GMM layer). The MM layer 408a may be configured to communicate with the AMF 404, and the SM layer 408b may be configured to communicate with the SMF 402. In some aspects, the UE 406 may send an SM message to the SMF 402 by generating an SM message at the SM layer 408b and passing the SM message to the MM layer 408a. The MM layer 408a may then encapsulate the SM message into an MM message and send the MM message to the AMF 404. The AMF 404 may then extract the SM message from the MM message and forward the SM message to the SMF 402.

[0065] In order to send an SM message to the SMF 402, the UE 406 may first establish a PDU session 422 with the SMF 402, for example, through the SM layer 408b of the UE 406. The PDU session 422 may be uniquely identified by an ID that separates the PDU session 422 from other PDU sessions, which may be established by one or more other SMFs. When establishing the PDU session 422, the UE 406 may select a slice associated with the SMF 402, or if the UE 406 does not select a slice, a slice may be assigned to the UE 406. In one aspect, the UE 406 may establish a PDU session 422 with the SMF for control plane CIoT 5GS optimization.

[0066] In some aspects, the UE 406 may be configured to send data via the control plane to the SMF 402. For example, when the UE 406 is in an idle mode (e.g., 5GMM idle mode), the UE 406 may include the data in a CPSR message, or when the UE 406 is in a connected mode (e.g., 5GMM connected mode), the UE 406 may include the data in another UL NAS message (e.g., UL NAS transport message).

[0067] In some other aspects, UE 406 may be configured to support SGC. SGC may use a service gap timer (e.g., timer T3447 in 5GS) to control the frequency at which the UE switches from idle mode to connected mode. For example, a back-off (BO) timer 410 may be implemented as a service gap timer. However, if UE 406 does not support SGC, AMF 404 may still manage SGC for UE 406. For example, AMF 404 may include a local timer 412 (e.g., timer T3447 in 5GS) associated with the SGC for UE 406. When the local timer 412 runs at AMF 404, UE 406 may be prohibited from switching to connected mode and / or may be prohibited from sending UL NAS messages in connected mode.

[0068] The SMF 402 may include limited resources and may therefore become congested. For example, the SMF 402 may lack sufficient resources to process all SM messages to be received and / or transmitted for all PDU sessions established through the SMF 402. The SMF 402 may become congested at one or more of a slice, a DNN, or a combination of both a slice and a DNN. Since communications with the SMF 402 may be configured through the AMF 404, the AMF 404 may apply congestion control for the SMF 402.

[0069] The SMF 402 may transmit a congestion indication 424 to the AMF 404, which may indicate that the SMF 402 is congested and / or lacks sufficient resources for further communication at one or more of a slice, a DNN, or a combination of both a slice and a DNN. The congestion indication 424 may include a reason code indicating the cause of the congestion, such as "congestion" (e.g., reason code #22 in 5GS), "insufficient resources for a particular slice and DNN" (e.g., reason code #67 in 5GS), or "insufficient resources for a particular slice" (e.g., reason code #69 in 5GS).

[0070] In response to the congestion indication 424, the AMF 404 may apply congestion control to the communication from the UE 406 to the SMF 402 through the AMF 404. At the UE 406, the congestion control for the SMF 402 may be applied through at least one BO timer 410 (e.g., one of the timers T3448, T3447, T3396, T3584, T3585 in 5G), which may be configured at the SM layer 408b of the UE 406. When the BO timer 410 is running, the UE 406 may be prohibited from sending data and requesting data for the PDU session 422. When the BO timer 410 expires, the UE 406 may resume sending SM messages and requesting data for the PDU session 422.

[0071] The UE 406 may determine whether the BO timer 410 that may be associated with the PDU session 422 is terminated. When the BO timer 410 is running, the BO timer 410 may not be terminated. When the UE 406 determines that the BO timer 410 is not terminated, the UE 406 may refrain from sending data to the SMF 402 and requesting data from the SMF 402 through the control plane associated with the PDU session 422. Accordingly, when the UE 406 determines that the BO timer 410 is terminated, the UE 406 may send data to the SMF 402 and request data from the SMF 402 through the control plane associated with the PDU session 422.

[0072] According to the first aspect, the UE 406 may be configured to apply the BO timer 410 at the SM layer 408b to limit the sending and requesting of data at the MM layer 408a. For example, when the BO timer 410 (e.g., the BO timer 410 may include at least one of the timer T3396 for DNN congestion, the timer T3584 for slice and DNN congestion, and / or the timer T3585 for slice congestion in the 5GS) is running, the SM layer 408b may be prohibited from sending SM signaling (e.g., control signaling). When the UE 406 may be configured to send data through the control plane for the PDU session 422, the UE 406 may be configured so that the BO timer 410 is extended to apply to data through the control plane for the PDU session 422, rather than only applying the BO timer 410 to the SM signaling (e.g., control signaling).

[0073] Furthermore, in such regards, when the BO timer 410 is running, the UE 406 may not send or request data over the control plane for the PDU session 422 established with the congested SMF 402 (e.g., unless the UE 406 is configured for high priority access in the selected PLMN or the PDU session 422 is an emergency PDU session). In fact, when the BO timer 410 is running, the SM layer 408b may be prohibited from initiating data transmission over the control plane and prohibited from requesting the MM layer 408a to send data over the control plane for the PDU session 422. For example, when the BO timer 410 is running and the UE 406 is in MM idle mode (e.g., 5G MM idle mode) for the PDU session 422, the UE 406 may be prohibited from sending data in a CPSR message over the control plane, the PDU session 422 correspondingly associated with the DNN and / or slice congested at the SMF 402. In another example, when the BO timer 410 is running and the UE 406 is in an MM connectivity mode (e.g., a 5GMM connectivity mode) for a PDU session 422, the UE 406 may be prohibited from sending data in a UL NAS transport message over the control plane, where the PDU session 422 is correspondingly associated with a DNN and / or slice that is congested at the SMF 402.

[0074] In some aspects, if the PDU session 422 is not the only control plane, the UE 406 may still be allowed to request establishment of user plane resources for the PDU session 422. For example, the UE 406 may request establishment of user plane resources for the PDU session 422 for control plane CIoT 5GS optimization even when the BO timer 410 is running.

[0075] When the BO timer 410 expires, the BO timer 410 may terminate. However, the BO timer 410 may be further terminated based on receiving data for the PDU session 422 at the SM layer 408b. When the BO timer 410 expires, the SM layer 408b may resume sending data and requesting data through the control plane for the PDU session 422 established with the SMF 402.

[0076] According to a second aspect, the AMF 404 may be configured to apply congestion control to a congested SMF 402 with which the UE 406 has established a PDU session 422. In such an aspect, the SM layer 408b may initially be unaware that the SMF 402 is congested, and thus the SM layer 408b may generate data 438 associated with the PDU session 422 to be sent to the SMF 402. The data 438 may be intended to be sent over the control plane and / or may be associated with an ID of the PDU session 422.

[0077] The SM layer 408b may provide the MM layer 408a with the data 438 and the ID of the PDU session 422 associated with the data 438. The MM layer 408a may encapsulate or group the SM message including the data 438 in a UL MM message 428. If the UE 406 is to send the UL MM message 428 in idle mode, the MM layer 408a may include the data 438 in a CPSR message. If the UE 406 is to send the UL MM message 428 in connected mode, the MM layer 408a may include the data 438 in a UL NAS transport message.

[0078] The MM layer 408a may include information indicating the ID of the PDU session 422 in the UL MM message 428. In some aspects, the UL MM message 428 may include a CIoT small data container IE, a payload container type IE, and / or a payload container IE, which may be inserted by the MM layer 408a based on the data 438. When sending data over the control plane, the MM layer 408a may include the data in the payload container IE and may set the payload container type IE to indicate "control plane data".

[0079] The AMF 404 may receive a UL MM message 438 for the congested SMF 402. In response, the AMF 404 may apply congestion control to the congested SMF 402. For example, the AMF 404 may generate a DL MM message 430, which may be a DL NAS transport message, a service rejection message, or a service acceptance message if the AMF 404 is only rejecting data for the PDU session 422 with the congested SMF 402 (e.g., because the AMF 404 may not reject all data for all PDU sessions).

[0080] In some aspects, if the UL MM message 428 includes a CIoT Small Data Container IE, the AMF 404 may include the same CIoT Small Data Container IE in the DL MM message 430. In such aspects, the AMF 404 may refrain from encrypting the value portion of the CIoT Small Data Container IE because the DL MM message 430 may be sent in an encrypted manner.

[0081] In some other aspects, if the UL MM message 428 includes a NAS message container IE having at least a payload container type IE, a payload container IE, and an ID of the PDU session 422, the AMF 404 may include at least the same payload container IE (e.g., including data 438), the ID of the PDU session 422, and / or the payload container type IE (e.g., indicating "control plane data") in the DL MM message 430.

[0082] In addition, the AMF 404 may include a value of the BO timer 410 in the DL MM message 430. In some aspects, the value may be based on a local timer 412 maintained at the AMF 404 (e.g., based on the congestion indication 424 from the SMF 402). For example, the local timer 412 may be a service gap timer (e.g., timer T3 447 in 5GS) maintained for the UE 406 (such as for a UE that does not support SGC).

[0083] In addition, the AMF 404 may include an indication of congestion experienced by the SMF 402, such as slice congestion, DNN congestion, or both slice and DNN congestion. To this end, the AMF 404 may include a cause code in the DL MM message 430. For example, the AMF 404 may include a cause code indicating "congestion" (e.g., 5GMM cause code #22), a cause code indicating "insufficient resources for a particular slice and DNN" (e.g., 5GMM cause code #67), or a cause code indicating "insufficient resources for a particular slice" (e.g., 5GMM cause code #69) in the DL MM message 430. These cause codes may be set by the policies of the operator of the AMF 404 and / or the SMF 402.

[0084] In some aspects, the AMF 404 may include a cause code in the DL MM message 430 that specifically indicates congestion of the SMF 402 with respect to data through the control plane. Such a cause code may be used to restrict data transmission by the UE 406 for the ID of the PDU session 422 through the control plane, but may not be related to SM signaling (e.g., control signaling). According to such a cause code, the UE 406 will still be able to send SM signaling for the PDU session 422 (assuming that the SMF 402 is not congested with respect to SM signaling). Thus, the BO timer 410 based on the DL MM message 430 indicating such a cause code may only prohibit the UE 406 from sending data for the PDU session 422 through the control plane.

[0085] Upon receipt of the DL MM message 430 by the UE 406, the MM layer 408a may identify the timer value included in the DL MM message 430. The MM layer 408a may pass the timer value to the SM layer 408b, and accordingly the SM layer 408b may set the BO timer 410 to the timer value indicated in the DL MM message 430. The SM layer 408b may then start the BO timer 410, which may limit data transmission and data requests associated with the PDU session 422 established with the congested SMF 402.

[0086] If the DL MM message 430 includes a payload container type IE indicating "control plane data", includes an ID of the PDU session 422, and / or includes a CIoT small data container IE, the MM layer 408a may return the data 438 included in the DL MM message 430 to the SM layer 408b.

[0087] Subsequently, the SM layer 408b may wait for the expiration of the BO timer 410. The BO timer 410 may be terminated upon expiration of the BO timer 410 and / or upon receipt of data from the SMF 402 through the control plane for the PDU session 422. When the BO timer 410 expires, the SM layer 410 may again pass the data 438, potentially together with the ID of the PDU session 422, to the MM layer 408a. The MM layer 408a may encapsulate or packetize the data 438 in a UL MM message 436 (e.g., a CPSR message or a UL NAS transport message), which may include the ID of the PDU session 422, and may send the UL MM message 436 to the AMF 404. In association with the PDU session 422, the AMF 404 may send the data 438 to the SMF 402, which may no longer be congested after the BO timer 410 expires.

[0088] Figure 5is a flow chart of a wireless communication method 500. The method 500 may be performed by a UE (e.g., UE 104, UE 350, UE 406, which may include memory 360 and may be the entire UE 350 or a component of the UE 350 (such as TX processor 368, RX processor 356 and / or controller / processor 359)). In various aspects, one or more of the illustrated operations may be omitted, swapped, and / or performed contemporaneously.

[0089] At 502, the UE may establish a PDU session with the SMF. The PDU session may be associated with an ID. For example, referring to Figure 4 , UE406 can establish a PDU session with SMF 402.

[0090] At 504, the UE may receive a message including the duration of the BO timer from the AMF. In some aspects, the message including the duration of the BO timer may be received based on a transmission of a CPSR or a UL NAS transport message by the UE to the AMF. One of the CPSR or the UL NAS transport message may indicate an ID associated with the PDU session. In addition, the received message including the duration of the BO timer may include at least one of an ID associated with the PDU session or a reason code associated with the BO timer. For example, the reason code may indicate that data passing through the control plane for the PDU session with the SMF is prohibited when the BO timer has not expired. In one aspect, the reason code may not be associated with SM signaling (e.g., control signaling), and therefore SM signaling may still be allowed when the BO has not expired. For example, referring to Figure 4 , the UE 406 may receive a DLMM message 430 indicating the duration of the BO timer 410 of the UE 406 .

[0091] At 506, the UE may set the BO timer to the duration indicated in the received message. According to various aspects, the BO timer may be associated with at least one of the DNN, the network slice, and / or the SGC (e.g., the timer may be one of the timers T3448, T3447, T3396, T3584, or T3585 of the 5GS). The BO timer may be configured at the SM layer of the UE (e.g., the 5GSM layer). For example, referring to Figure 4 , the UE 406 may set the BO timer 410 based on the duration indicated in the DL MM message 430.

[0092] At 508, the UE may determine whether the BO timer is terminated or not. The BO timer may be terminated based on at least one of expiration of the BO timer, receipt of an SM message (e.g., from the AMF or from the SMF) indicating that the BO timer will be terminated, and / or receipt of DL data via a control plane associated with the established PDU session. For example, referring to Figure 4 , UE 406 may determine whether BO timer 410 is expired or not.

[0093] If the BO timer has not expired, method 500 may proceed to 510. At 510, the UE may refrain from sending or requesting data via a control plane associated with the PDU session. Figure 4 , when the BO timer 410 has not expired, the UE 406 may refrain from sending a UL MM message associated with the PDU session 422.

[0094] If the BO timer expires, method 500 may proceed to 512. At 512, the UE may send or request data via a control plane associated with the PDU session. Figure 4 , UE 406 can send or request data via the control plane associated with PDU session 422.

[0095] Figure 6 6 is a flow chart of a wireless communication method 600. The method 600 may be performed by an AMF (e.g., AMF 192, other AMF 193, base station 310, AMF 404, which may include memory 376 and may be the entire base station 310 or a component of the base station 310 (such as TX processor 316, RX processor 370 and / or controller / processor 375)). In various aspects, one or more of the illustrated operations may be omitted, swapped, and / or performed concurrently.

[0096] At 602, the AMF may receive a message from the SMF indicating a congestion status associated with the SMF. The congestion status may indicate that at least one of the DNN, the network slice, and / or the control plane is congested at the SMF. For example, referring to Figure 4 , AMF404 can receive congestion indication 424 from SMF 402.

[0097] At 604, the AMF may maintain a local timer associated with the PDU session established between the SMF and the UE. The local timer may be associated with at least one of a DNN, a network slice, or an SGC associated with the UE and / or the PDU session. For example, referring to Figure 4 , the AMF 404 may maintain a local timer 412 in association with a PDU session 422 established between the UE 406 and the SMF 402.

[0098] At 606, the AMF may receive a UL MM message from the UE. The UL MM message may include data via a control plane associated with the PDU session. The UL MM message may be one of a CPSR message or a UL NAS transport message. For example, referring to Figure 4, AMF 404 may receive UL MM message 428 from UE 406.

[0099] At 608, the AMF may determine whether the UE is allowed or prohibited from sending data via a control plane associated with a PDU session established between the SMF and the UE. In one aspect, the AMF may make the determination based on a congestion status received from the SMF. In another aspect, the AMF may make the determination based on a local timer that may be associated with the SGC of the UE. When the local timer is running, the AMF may determine that the UE is prohibited from sending data via a control plane associated with the PDU session. For example, referring to Figure 4 , the AMF 404 may determine, for example, based on the congestion indication 424 and / or based on the local timer 412, whether the UE 406 is allowed or prohibited from sending data over the control plane associated with the PDU session 422.

[0100] If the AMF determines that the UE is prohibited from sending data to the SMF through the control plane associated with the PDU session, method 600 may proceed to 610. At 610, the AMF may send a DL message including the duration of the BO timer to the UE. The BO timer may be associated with at least one of the DNN, network slice, and / or SGC for the UE and / or for the PDU session. The DL message may be one of a service acceptance message, a service rejection message, or a DL NAS transport message. The AMF may include a cause code in the DL message. When the BO timer of the UE is not terminated, the cause code may indicate that the SM signaling (e.g., control signaling) associated with the PDU session is not affected and / or is allowed for the UE, that is, the cause code may be associated only with data through the control plane associated with the PDU session. In some aspects, the DL message may include at least one of an ID associated with the PDU session, data included in a UL MM message received from the UE, and / or a container type associated with the UL MM message. In some other aspects, the duration of the BO timer included in the DL message may be equal to a local timer maintained by the AMF, for example, the duration may be equal to a local SGC timer maintained by the AMF for the UE, such as when the UE does not support SGC. Figure 4 , the AMF may send a DL MM message 430 to the UE 406.

[0101] If the AMF determines that the UE is allowed to send data to the SMF via the control plane associated with the PDU session, the method 600 may proceed to 612. At 612, the AMF may send the data to the SMF via the control plane. Figure 4 , AMF 404 can send data 438 to SMF 402 through this control surface.

[0102] It should be understood that the specific order or hierarchy of each box in the disclosed process / flowchart is an illustration of an example approach. It should be understood that the specific order or hierarchy of each box in these process / flowcharts can be rearranged based on design preferences. In addition, some boxes can be combined or omitted. The attached method claims present the elements of various boxes in an exemplary order and are not meant to be limited to the specific order or hierarchy presented.

[0103] 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 easily understood by those skilled in the art, and the universal principles defined in this article can be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown in this article, but should be granted the full scope consistent with the claims in language, wherein the singular reference of the elements is not intended to represent "there is and only one", but "one or more", unless otherwise stated. The wording "exemplary" is used in this article to represent "used as an example, instance, or explanation". Any aspect described as "exemplary" herein does not have to be interpreted as being superior to or superior to other aspects. Unless otherwise stated, the term "some / certain" 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 multiple A, multiple B or multiple 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, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are currently or hereafter known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly stated in the claims. The terms "module," "mechanism," "element," "device," and the like may not be a substitute for the term "means." Thus, no claim element should be interpreted as a means-plus-function unless the element is explicitly stated using the phrase "means for..."

Claims

1. A method for wireless communication by a user equipment (UE), the method comprising: Establishing a protocol data unit (PDU) session with a session management (SM) function (SMF); receiving, from an access and mobility management function (AMF), a message including the duration of a back-off timer, wherein the message further includes an identifier (ID) associated with the PDU session, wherein the message is received based on transmission of one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message to the AMF, and wherein the one of the CPSR message or the uplink NAS transport message indicates the ID associated with the PDU session; Setting the backoff timer to the duration; Starting the backoff timer; determining whether the backoff timer associated with the PDU session has expired; When the backoff timer has not expired, suppressing sending data to the SMF through the control plane associated with the PDU session; as well as When the backoff timer expires, the data is sent to the SMF via the control plane associated with the PDU session.

2. The method of claim 1, wherein the message including the duration of the backoff timer further includes a reason code associated with the backoff timer.

3. The method of claim 2, wherein the cause code indicates that SM signaling associated with control information is allowed when the backoff timer has not expired.

4. The method of claim 1, wherein the backoff timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

5. The method of claim 1, wherein the back-off timer is configured at a SM layer of the UE.

6. The method of claim 1 , wherein the backoff timer is terminated based on at least one of expiration of the backoff timer, receipt of an SM message indicating that the backoff timer will terminate, or receipt of downlink data from the SMF via the control plane associated with the PDU session.

7. A method for wireless communication by an access and mobility management function (AMF), the method comprising: receiving a mobility management (MM) message from a user equipment (UE), wherein the MM message includes data over a control plane associated with a protocol data unit (PDU) session established between the UE and a session management (SM) function (SMF); determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session; When the UE is prohibited from sending the data to the SMF through the control plane, sending a first message including the duration of a first backoff timer to the UE, wherein the first message further includes an identifier (ID) associated with the PDU session; and When the UE is allowed to send the data to the SMF through the control plane, the UE sends the data to the SMF through the control plane.

8. The method of claim 7, wherein the MM message comprises one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transmission message.

9. The method of claim 7, wherein the first message comprises at least one of a service accept message, a service reject message, or a downlink non-access stratum (NAS) transmission message.

10. The method of claim 7, further comprising: receiving from the SMF a second message indicating a congestion status associated with the SMF, Wherein determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the congestion status.

11. The method of claim 10, wherein the congestion state is associated with at least one of a data network name (DNN) or a network slice.

12. The method of claim 10, wherein a reason code is included in the first message based on the congestion status.

13. The method of claim 12, wherein the cause code indicates that SM signaling associated with control information is allowed by the UE when the first backoff timer has not expired.

14. The method of claim 7, wherein the first message further includes at least one of the data included in the MM message, or a container type associated with the MM message.

15. The method of claim 7, wherein the first backoff timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

16. The method of claim 7, further comprising: maintaining a local back-off timer associated with the PDU session established between the UE and the SMF, The determination of whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the local backoff timer.

17. The method of claim 16, wherein the local back-off timer comprises a service gap control (SGC) timer, and wherein the duration of the first back-off timer included in the first message is based on the SGC timer when the UE does not support SGC.

18. A user equipment (UE), comprising: means for establishing a protocol data unit (PDU) session with a session management (SM) function (SMF); means for receiving a message including a duration of a back-off timer from an access and mobility management function (AMF), wherein the message further includes an identifier (ID) associated with the PDU session, wherein the message is received based on transmission of one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message to the AMF, and wherein the one of the CPSR message or the uplink NAS transport message indicates the ID associated with the PDU session; means for setting a backoff timer to said duration; means for starting the back-off timer; means for determining whether the backoff timer associated with the PDU session has expired; means for inhibiting, when the backoff timer has not expired, sending data to the SMF via a control plane associated with the PDU session; as well as Means for sending the data to the SMF via the control plane associated with the PDU session when the backoff timer expires.

19. The UE of claim 18, wherein the message including the duration of the back-off timer further includes a cause code associated with the back-off timer.

20. The UE of claim 19, wherein the cause code indicates that SM signaling associated with control information is allowed when the backoff timer has not expired.

21. The UE of claim 18, wherein the back-off timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

22. The UE of claim 18, wherein the back-off timer is configured at a SM layer of the UE.

23. The UE of claim 18, wherein the backoff timer is terminated based on at least one of expiration of the backoff timer, receipt of an SM message indicating that the backoff timer will terminate, or receipt of downlink data from the SMF through the control plane associated with the PDU session.

24. An access and mobility management function (AMF), comprising: means for receiving a mobility management (MM) message from a user equipment (UE), wherein the MM message comprises data over a control plane associated with a protocol data unit (PDU) session established between the UE and a session management (SM) function (SMF); means for determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session; means for sending a first message including a duration of a first backoff timer to the UE when the UE is prohibited from sending the data to the SMF through the control plane, wherein the first message further includes an identifier (ID) associated with the PDU session; and Means for sending the data to the SMF through the control plane when the UE is allowed to send the data to the SMF through the control plane.

25. The AMF of claim 24, wherein the MM message comprises one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message.

26. The AMF of claim 24, wherein the first message comprises at least one of a service accept message, a service reject message, or a downlink non-access stratum (NAS) transport message.

27. The AMF of claim 24, further comprising: means for receiving from said SMF a second message indicating a congestion status associated with said SMF, Wherein determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the congestion status.

28. The AMF of claim 27, wherein the congestion state is associated with at least one of a data network name (DNN) or a network slice.

29. The AMF of claim 27, wherein a reason code is included in the first message based on the congestion status.

30. The AMF of claim 29, wherein the cause code indicates that SM signaling associated with control information is allowed by the UE when the first backoff timer has not expired.

31. The AMF of claim 24, wherein the first message further includes at least one of the data included in the MM message, or a container type associated with the MM message.

32. The AMF of claim 24, wherein the first backoff timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

33. The AMF of claim 24, further comprising: means for maintaining a local back-off timer associated with the PDU session established between the UE and the SMF, The determination of whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the local backoff timer.

34. The AMF of claim 33, wherein the local back-off timer comprises a service gap control (SGC) timer, and wherein the duration of the first back-off timer included in the first message is based on the SGC timer when the UE does not support SGC.

35. A user equipment (UE), comprising: Memory; as well as at least one processor coupled to the memory and configured to: Establishing a protocol data unit (PDU) session with a session management (SM) function (SMF); receiving, from an access and mobility management function (AMF), a message including the duration of a back-off timer, wherein the message further includes an identifier (ID) associated with the PDU session, wherein the message is received based on transmission of one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message to the AMF, and wherein the one of the CPSR message or the uplink NAS transport message indicates the ID associated with the PDU session; Setting the backoff timer to the duration; Starting the backoff timer; determining whether the backoff timer associated with the PDU session has expired; When the backoff timer has not expired, suppressing sending data to the SMF through the control plane associated with the PDU session; as well as When the backoff timer expires, the data is sent to the SMF via a control plane associated with the PDU session.

36. The UE of claim 35, wherein the message including the duration of the back-off timer further includes a cause code associated with the back-off timer.

37. The UE of claim 36, wherein the cause code indicates that SM signaling associated with control information is allowed when the backoff timer has not expired.

38. The UE of claim 35, wherein the back-off timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

39. The UE of claim 35, wherein the back-off timer is configured at a SM layer of the UE.

40. The UE of claim 35, wherein the backoff timer is terminated based on at least one of expiration of the backoff timer, receipt of an SM message indicating that the backoff timer will terminate, or receipt of downlink data from the SMF via the control plane associated with the PDU session.

41. An access and mobility management function (AMF), comprising: Memory; as well as at least one processor coupled to the memory and configured to: receiving a mobility management (MM) message from a user equipment (UE), wherein the MM message includes data over a control plane associated with a protocol data unit (PDU) session established between the UE and a session management (SM) function (SMF); determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session; When the UE is prohibited from sending the data to the SMF through the control plane, sending a first message including the duration of a first backoff timer to the UE, wherein the first message further includes an identifier (ID) associated with the PDU session; and When the UE is allowed to send the data to the SMF through the control plane, the UE sends the data to the SMF through the control plane.

42. The AMF of claim 41, wherein the MM message comprises one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message.

43. The AMF of claim 41, wherein the first message comprises at least one of a service accept message, a service reject message, or a downlink non-access stratum (NAS) transport message.

44. The AMF of claim 41, wherein the at least one processor is further configured to: receiving from the SMF a second message indicating a congestion status associated with the SMF, Wherein determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the congestion status.

45. The AMF of claim 44, wherein the congestion state is associated with at least one of a data network name (DNN) or a network slice.

46. ​​The AMF of claim 44, wherein a reason code is included in the first message based on the congestion status.

47. The AMF of claim 46, wherein the cause code indicates that SM signaling associated with control information is allowed by the UE when the first backoff timer has not expired.

48. The AMF of claim 41, wherein the first message further includes at least one of the data included in the MM message, or a container type associated with the MM message.

49. The AMF of claim 41, wherein the first backoff timer is associated with at least one of a data network name (DNN), a network slice, or a service gap control (SGC).

50. The AMF of claim 41, wherein the at least one processor is further configured to: maintaining a local back-off timer associated with the PDU session established between the UE and the SMF, The determination of whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session is based on the local backoff timer.

51. The AMF of claim 50, wherein the local back-off timer comprises a service gap control (SGC) timer, and wherein the duration of the first back-off timer included in the first message is based on the SGC timer when the UE does not support SGC.

52. A computer readable medium storing computer executable code for wireless communication by a user equipment (UE), the computer executable code comprising code for: Establishing a protocol data unit (PDU) session with a session management (SM) function (SMF); receiving, from an access and mobility management function (AMF), a message including the duration of a back-off timer, wherein the message further includes an identifier (ID) associated with the PDU session, wherein the message is received based on transmission of one of a control plane service request message (CPSR) or an uplink non-access stratum (NAS) transport message to the AMF, and wherein the one of the CPSR message or the uplink NAS transport message indicates the ID associated with the PDU session; Setting the backoff timer to the duration; Starting the backoff timer; determining whether the backoff timer associated with the PDU session has expired; When the backoff timer has not expired, suppressing sending data to the SMF through the control plane associated with the PDU session; as well as When the backoff timer expires, the data is sent to the SMF via a control plane associated with the PDU session.

53. A computer readable medium storing computer executable code for wireless communications by an access and mobility management function (AMF), the computer executable code comprising code for: receiving a mobility management (MM) message from a user equipment (UE), wherein the MM message includes data over a control plane associated with a protocol data unit (PDU) session established between the UE and a session management (SM) function (SMF); determining whether the UE is allowed or prohibited from sending the data to the SMF through the control plane for the PDU session; When the UE is prohibited from sending the data to the SMF through the control plane, sending a first message including the duration of a first backoff timer to the UE, wherein the first message further includes an identifier (ID) associated with the PDU session; and When the UE is allowed to send the data to the SMF through the control plane, the UE sends the data to the SMF through the control plane.

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