CN111034329A - Uplink early data transmission - Google Patents

Abstract

A method of wireless communication by a User Equipment (UE) without a Radio Resource Control (RRC) connection to a base station includes receiving system information from the base station and transmitting data communication on a control plane to the base station without establishing an RRC connection with the base station. A UE in an RRC suspended state may transmit data communications to a base station on a user plane without resuming an RRC connection with the base station. The data communication may include data as well as UE identity information and/or a cause indication. The base station may indicate resources for transmitting data communication information in the system information and receive data communication on the control plane without establishing an RRC connection with the UE or on the user plane without resuming the RRC connection with the RRC-suspended UE.

Description

Uplink early data transmission

Cross Reference to Related Applications

The present application claims U.S. application S/N.15/964,523 entitled "Uplink Small Data Transmission for Enhanced Machine Type Communication (EMTC) And Internet Of Things (IOT) Communication" filed on 27.4.2018 And U.S. provisional patent application No.62/544,703 entitled "Uplink Early Data Transmission for Cellular Internet Of Things (IOT) Communication" filed on 11.8.2017, and U.S. patent application No.16/024,421 entitled Uplink Early Data Transmission filed on 29.6.2018, the contents of each of which are expressly incorporated herein by reference in their entirety.

Background

Technical Field

The present disclosure relates generally to communication systems, and more particularly to early uplink data transmission for enhanced machine type communication (eMTC) and internet of things (IoT) communication.

Introduction to the design reside in

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple-access techniques capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access techniques 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 techniques have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate on a city, country, region, and even global level. An example telecommunication standard is the 5G New Radio (NR). The 5G NR is part of 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 IoT), and other requirements. Some aspects of the 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There is a need for further improvements in the 5G NR technology. These improvements are also applicable to other multiple access techniques and telecommunications standards employing these techniques.

Machine Type Communication (MTC) generally refers to communication characterized by automatic data generation, exchange, processing, and actuation between machines with little or no human intervention.

IoT is an interconnected network of physical devices, vehicles (sometimes referred to as "connected devices" and/or "smart devices"), buildings, and other items that may be embedded in network connectivity of electronic devices, software, sensors, actuators, and the like that enable these objects to collect and exchange data and other information.

Many MTC and IoT applications may involve relatively infrequent exchanges of small amounts of data (e.g., one uplink packet). For example, metering, alarms, etc. are expected to produce small amounts of Uplink (UL) data. Similarly, queries, notifications of updates, and commands to actuators, for example, generate small Downlink (DL) data transmissions.

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.

When the user equipment is in an idle state, a large amount of overhead is required in order to set up or resume a Radio Resource Control (RRC) connection. Accordingly, for MTC or IoT applications, there may be significant consumption of resources for small data transmissions (e.g., 1 uplink packet or 1 Media Access Control (MAC) block). Therefore, it is desirable to minimize the amount of resources used in MTC and IoT communications.

Aspects of the present disclosure relate to reducing overhead for setting up or resuming an RRC connection to communicate small data transmissions. When the RRC connection of the UE is in an idle state or a suspended state, a large amount of overhead is required to set up or resume the RRC connection for data transmission. When data transmission is for MTC or IoT applications, this may require a large consumption of resources for small data transmissions (e.g., 1 Media Access Control (MAC) block). For example, in conventional techniques, numerous communication steps are performed by the UE and/or the base station to establish an RRC connection or to resume an RRC connection before data can be transmitted. Furthermore, after the data transmission, an additional step is performed to release the RRC connection. In contrast, aspects of the present disclosure provide for data transmission (e.g., uplink data transmission) from a UE having an RRC connection in an idle state or a suspended state without transitioning to an RRC connected state. Data transmission without performing the RRC establishment procedure or without recovering the RRC connection may be referred to as Early Data Transmission (EDT) or data transmission in RRC connectionless mode.

In an aspect of the disclosure, a method, computer-readable medium, and apparatus for wireless communication at a User Equipment (UE) are provided. The apparatus includes a memory and one or more processors coupled to the memory. The apparatus receives system information from a base station and transmits data communication on a control plane to the base station without establishing an RRC connection with the base station, wherein the data communication includes data and at least one of: UE identity information and a cause indication.

In another aspect of the disclosure, a method, computer-readable medium, and apparatus for wireless communication at a base station are provided. The apparatus includes a memory and one or more processors coupled to the memory. The apparatus indicates resources in system information and receives data communication from a UE on a control plane without establishing an RRC connection with the UE, wherein the data communication includes data and at least one of: UE identity information and a cause indication.

In another aspect of the disclosure, a method, computer-readable medium, and apparatus for wireless communication at a UE (e.g., in an RRC suspended state) are provided. The apparatus includes a memory and one or more processors coupled to the memory. The apparatus receives system information from a base station and transmits a data communication to the base station on a user plane without restoring an RRC connection with the base station, wherein the data communication includes data and at least one of: UE identity information and a cause indication.

In an aspect of the disclosure, a method, computer-readable medium, and apparatus for wireless communication at a base station are provided. The apparatus includes a memory and one or more processors coupled to the memory. The apparatus indicates resources in system information and receives a data communication from a UE on a user plane without restoring an RRC connection with the UE, wherein the data communication includes data and at least one of: UE identity information and a cause indication.

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 the present description is intended to include all such aspects and their equivalents.

Brief Description of Drawings

Fig. 1 is a diagram illustrating an example of a wireless communication system and an access network.

Fig. 2A, 2B, 2C, and 2D are diagrams illustrating examples of a DL frame structure, DL channels within the DL frame structure, an UL frame structure, and UL channels within the UL frame structure, respectively.

Fig. 3 is a diagram illustrating an example of a base station and a User Equipment (UE).

Fig. 4 is a diagram illustrating an example communication system including a base station and a UE.

Fig. 5 and 6 are example call flow diagrams in accordance with aspects of the present disclosure.

Fig. 7 is a flow chart of a method of wireless communication.

Fig. 8 is a conceptual data flow diagram illustrating the data flow between different devices/components in an example apparatus.

Fig. 9 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

Fig. 10 is a flow chart of a method of wireless communication.

Fig. 11 is a conceptual data flow diagram illustrating the data flow between different devices/components in an example apparatus.

Fig. 12 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

Fig. 13 is a flow chart of a method of wireless communication.

Fig. 14 is a conceptual data flow diagram illustrating the data flow between different devices/components in an example apparatus.

Fig. 15 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

Fig. 16 is a flow chart of a method of wireless communication.

Fig. 17 is a conceptual data flow diagram illustrating the data flow between different devices/components in an example apparatus.

Fig. 18 is a diagram illustrating an example of a hardware implementation of an apparatus employing a processing system.

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 to provide a thorough understanding of the various concepts. It will be apparent, however, to one 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 a telecommunications system will now be presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and are 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.

As an 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: a microprocessor, a microcontroller, a Graphics Processing Unit (GPU), a Central Processing Unit (CPU), an application processor, a Digital Signal Processor (DSP), a Reduced Instruction Set Computing (RISC) processor, a system-on-chip (SoC), a baseband processor, a Field Programmable Gate Array (FPGA), a Programmable Logic Device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionalities described throughout this disclosure. One or more processors in the processing system may execute software. Software should be construed broadly to mean instructions, instruction sets, code segments, program code, programs, subprograms, software components, applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to in software, firmware, middleware, microcode, hardware description language, or other terminology.

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 or encoded as one or more instructions or code on a computer-readable medium. Computer readable media includes computer storage media. A 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 Random Access Memory (RAM), Read Only Memory (ROM), electrically erasable programmable ROM (eeprom), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the preceding 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 and that can be accessed by a computer.

Aspects of the present disclosure relate to MTC and/or IoT communications in which a UE is in an idle mode or a suspended mode when data transmission is initiated. When the UE is in idle mode or suspended mode when a data transmission is initiated, conventional techniques perform a full radio resource control connection establishment procedure prior to the data transmission. A full Radio Resource Control (RRC) connection establishment procedure for an idle User Equipment (UE) involves a Random Access (RA) procedure. The RA procedure may be used to initiate data transfer, but with large overhead costs and delay times. For example, in conventional techniques, the RA procedure may include a series of messages including: msg1 (physical random access channel PRACH preamble), Msg2 (random access request (RAR)), Msg3(RRC connection request, RRC connection reestablishment request, RRC connection resume request, etc. depending on the reason of the RA procedure), Msg4 (early contention resolution, RRC connection setup, etc.), and finally Msg5 (which can be used for UL data (unless SR/BSR is required before actual payload transmission). This involves 5 or more messages for UL data before the actual payload transmission. This is a large overhead for applications transmitting uplink data adapted to one Transport Block Size (TBS).

After completion of the RA procedure, DL/UL transmission may be performed. As such, conventional approaches perform a large number of message exchanges before the actual payload transmission (even very small and/or infrequent payloads).

To address these and other issues, aspects of the present disclosure provide early uplink data transmission and other enhancements for MTC and/or IoT communications. That is, rather than scheduling the first UL data transmission in Msg5 or a later message as in conventional techniques, the data transmission in UL may convey data (e.g., payload) in Msg1 or Msg3, for example. In some aspects, enhancements may be applicable to Control Plane (CP)/User Plane (UP) cellular IoT evolved packet system. By providing early uplink data transmission for UEs in idle or suspended mode for MTC and IoT, power consumption, latency, and system overhead may be beneficially reduced.

In one example aspect, the data transmission information may be included in Msg3 and transmitted to a base station (e.g., an enodeb). As used herein, data transmission may refer to user data. The transmission of Msg3 may be performed on an initial UL grant provided by a Random Access Request (RAR). Msg3 may also convey a non-access stratum (NAS) UE identifier without a NAS message (e.g., a mobility management message) for initial access. Msg3 transmission may be performed using a separate Msg3 buffer, which may have higher priority than the UL buffer. Msg3 may use hybrid automatic repeat request (HARQ). In addition, the UE Medium Access Control (MAC) layer includes a HARQ entity and may retransmit the message if the UE does not receive a MAC layer response from the base station. For example, if the UE does not receive Msg4 (which may result in a failure of contention resolution), the UE (mac) layer may reattempt access from the idle state.

As presented herein, the RA procedure may be enhanced to support UL data transmission in Msg 3. In one example, a payload (e.g., a Service Data Unit (SDU)) can be included as a Common Control Channel (CCCH) SDU.

Fig. 1 is a diagram illustrating an example of a wireless communication system and an access network 100. A wireless communication system, also referred to as a Wireless Wide Area Network (WWAN), includes a base station 102, a UE 104, and an Evolved Packet Core (EPC) 160. Base station 102 may include macro cells (high power cellular base stations) and/or small cells (low power cellular base stations). The macro cell includes a base station. Small cells include femtocells, picocells, and microcells.

The base stations 102, collectively referred to as the evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), interface with the EPC160 over a backhaul link 132 (e.g., the S1 interface). Among other functions, the base station 102 may perform one or more of the following functions: communication 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 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 over the backhaul link 134 (e.g., the X2 interface), either directly or indirectly (e.g., through the EPC 160). The backhaul link 134 may be wired or wireless.

The base station 102 may communicate wirelessly with the UE 104. Each base station 102 may provide communication coverage for a respective 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 areas 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. The heterogeneous network may also include a home evolved node B (eNB) (HeNB), which may provide services to a restricted group referred to as a Closed Subscriber Group (CSG). The communication link 120 between the base station 102 and the UE 104 may include UL (also referred to as reverse link) transmissions from the UE 104 to the base station 102 and/or DL (also referred to as forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna techniques including spatial multiplexing, beamforming, and/or transmit diversity. These communication links may be over one or more carriers. For each carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) for transmission in each direction, the base station 102/UE 104 may use a spectrum of up to Y MHz (e.g., 5, 10, 15, 20, 100MHz) bandwidth. These 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 than 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).

Certain UEs 104 may communicate with each other using a device-to-device (D2D) communication link 192. The D2D communication link 192 may use DL/UL WWAN spectrum. The D2D communication link 192 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 over a variety of wireless D2D communication systems such as, for example, FlashLinQ, WiMedia, bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

The wireless communication system may further include a Wi-Fi Access Point (AP)150 in communication with a Wi-Fi Station (STA)152 via a communication link 154 in a 5GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152/AP 150 may perform a Clear Channel Assessment (CCA) prior to the communication to determine whether the channel is available.

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

g B node (gNB)180 may operate in 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 the portion of the RF in the electromagnetic spectrum. The EHF has a range of 30GHz to 300GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in this frequency band may be referred to as millimeter waves. Near mmW can extend down to frequencies of 3GHz and wavelengths of 100 mm. The ultra-high frequency (SHF) band extends between 3GHz to 30GHz, which is also known as a centimeter wave. Communications using the mmW/near mmW radio frequency band have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 184 with the UE 104 to compensate for the very high path loss and short range.

The EPC160 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. MME 162 may be in communication with Home Subscriber Server (HSS) 174. MME 162 is a control node that handles signaling between UE 104 and EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are passed through the serving gateway 166, which serving gateway 166 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 BM-SC 170 are connected to an IP service 176. IP services 176 may include the internet, intranets, IP Multimedia Subsystem (IMS), PS streaming services, and/or other IP services. The BM-SC 170 may provide functionality for MBMS user service provisioning and delivery. The BM-SC 170 may be used 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 broadcasting a particular service and may be responsible for session management (start/stop) and for collecting eMBMS-related charging information.

A base station may also be called a gbb, 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), or some other suitable terminology. The base station 102 provides an access point for the UE 104 to the EPC 160. 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 gaming console, a tablet device, a smart device, a wearable device, a vehicle, an electricity meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a display, or any other similar functioning device. The UE 104 may be referred to as an IoT device (e.g., a parking meter, a gas pump, an oven, a vehicle, a heart monitor, 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 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.

Referring again to fig. 1, in certain aspects, the UE 104/base station 180 may be configured to send and receive data communication information, respectively, without establishing an RRC connection (198).

Fig. 2A is a diagram 200 illustrating an example of a DL frame structure. Fig. 2B is a diagram 230 illustrating an example of channels within a DL frame structure. Fig. 2C is a diagram 250 illustrating an example of a UL frame structure. Fig. 2D is a diagram 280 illustrating an example of channels within a UL frame structure. Other wireless communication technologies may have different frame structures and/or different channels. A frame (10ms) may be divided into 10 equally sized subframes. Each subframe may include two consecutive slots. A resource grid may be used to represent the two slots, each slot including one or more time-concurrent Resource Blocks (RBs) (also known as physical RBs (prbs)). The resource grid is divided into a plurality of Resource Elements (REs). For a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols in the time domain (OFDM symbols for DL; SC-FDMA symbols for UL), for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

As illustrated in fig. 2A, some REs carry DL reference (pilot) signals (DL-RSs) used for channel estimation at the UE. The DL-RS may include cell-specific reference signals (CRS) (also sometimes referred to as common RS), UE-specific reference signals (UE-RS), and channel state information reference signals (CSI-RS). Fig. 2A illustrates CRSs (indicated as R, respectively) for antenna ports 0, 1, 2, and 3₀、R₁、R₂And R₃) UE-RS (indicated as R) for antenna port 5₅) And CSI-RS (indicated as R) for antenna port 15.

Fig. 2B illustrates an example of various channels within the DL subframe of a frame. The Physical Control Format Indicator Channel (PCFICH) is within symbol 0 of slot 0 and carries a Control Format Indicator (CFI) indicating whether the Physical Downlink Control Channel (PDCCH) occupies 1, 2, or 3 symbols (fig. 2B illustrates a PDCCH occupying 3 symbols). The PDCCH carries Downlink Control Information (DCI) within one or more Control Channel Elements (CCEs), each CCE includes nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. The UE may be configured with a UE-specific enhanced pdcch (epdcch) that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs (fig. 2B shows 2 RB pairs, each subset including 1 RB pair). A physical hybrid automatic repeat request (ARQ) (HARQ) indicator channel (PHICH) is also within symbol 0 of slot 0 and carries HARQ Indicators (HIs) indicating HARQ Acknowledgement (ACK)/negative ACK (nack) feedback based on a Physical Uplink Shared Channel (PUSCH). The Primary Synchronization Channel (PSCH) may be within symbol 6 of slot 0 within subframes 0 and 5 of the frame. The PSCH carries a Primary Synchronization Signal (PSS) that is used by the UE 104 to determine subframe/symbol timing and physical layer identity. The Secondary Synchronization Channel (SSCH) may be within symbol 5 of slot 0 within subframes 0 and 5 of the frame. The SSCH carries a Secondary Synchronization Signal (SSS) that is used by the UE to determine the 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 may determine a Physical Cell Identifier (PCI). Based on the PCI, the UE may determine the location of the aforementioned DL-RS. A Physical Broadcast Channel (PBCH) carrying a Master Information Block (MIB) may be logically grouped with PSCHs and SSCHs to form a Synchronization Signal (SS) block. The MIB provides the number of RBs in the DL system bandwidth, PHICH configuration, and System Frame Number (SFN). The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information, such as System Information Blocks (SIBs), which are not transmitted through the PBCH, and a paging message.

As illustrated in fig. 2C, some REs carry demodulation reference signals (DM-RS) used for channel estimation at the base station. The UE may additionally transmit a Sounding Reference Signal (SRS) in a last symbol of the subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of comb teeth (comb). The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling on the UL.

Fig. 2D illustrates an example of various channels within the UL subframe of a frame. A Physical Random Access Channel (PRACH) may be within one or more subframes within a frame based on a PRACH configuration. The PRACH may include 6 consecutive RB pairs within a subframe. The PRACH allows the UE to perform initial system access and achieve UL synchronization. The Physical Uplink Control Channel (PUCCH) may be located at the edge of the UL system bandwidth. The PUCCH carries Uplink Control Information (UCI) such as scheduling request, 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 Buffer Status Reports (BSRs), Power Headroom Reports (PHR), and/or UCI.

Fig. 3 is a block diagram of a base station 310 in communication with a UE350 in an access network. In the DL, IP packets from EPC160 may be provided to 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 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 broadcast 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 of UE measurement reports; PDCP layer functionality associated with header compression/decompression, security (ciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer Packet Data Units (PDUs), error correction by ARQ, concatenation, segmentation, and reassembly of RLC Service Data Units (SDUs), re-segmentation of RLC data PDUs, and re-ordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing MAC SDUs onto Transport Blocks (TBs), demultiplexing MAC SDUs from TBs, scheduling information reporting, error correction by 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 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 onto the physical channel, modulation/demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 processes 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 OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM stream is spatially precoded to produce a plurality of spatial streams. The channel estimates from channel estimator 374 may be used to determine coding and modulation schemes and 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 318 TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE350, 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 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 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 UE350, they may be combined into a single OFDM symbol stream by the RX processor 356. 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 most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by channel estimator 358. These 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. These data and control signals are then provided to a controller/processor 359 that implements layer 3 and layer 2 functionality.

The controller/processor 359 can be associated with 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, 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.

Similar to the functionality described in connection with the DL transmission by base station 310, 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 (ciphering, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction by ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and re-ordering 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 by HARQ, priority handling, and logical channel prioritization.

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

UL transmissions are processed at the base station 310 in a manner similar to that described in connection with 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 RX processor 370.

The controller/processor 375 can be associated with a memory 376 that stores program codes and data. 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, cipher interpretation, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from controller/processor 375 may be provided to EPC 160. The controller/processor 375 is also responsible for error detection using ACK and/or NACK protocols to support HARQ operations.

In one example aspect, one or both of the base station 310 and the UE350 may have logic, software, firmware, configuration files, etc. to allow MCT/IoT communications as described herein.

Fig. 4 is a diagram 400 illustrating a communication system in accordance with aspects of the present disclosure. Fig. 4 includes a node 402 and a plurality of UEs 404, 406. The UEs 404 may include MTC UEs, IoT UEs, reduced bandwidth low complexity (BL) UEs, and the like. The UE406 may also include an MTC UE, IoT UE, or BL UE, or the UE406 may communicate with a base station in a different manner than MTC, IoT, BL. The node 402 may be a macro node (e.g., a base station), a femto node, a pico node, or similar base station, a mobile base station, a relay, a UE (e.g., communicating with another UE in a peer-to-peer or ad hoc mode), a portion thereof, and/or substantially any component that communicates control data in a wireless network. UE404 and UE406 may each be a mobile terminal, a stationary terminal, a modem (or other tethered device), a portion thereof, and/or substantially any device that receives control data in a wireless network.

As shown in fig. 4, the UE404 receives a DL transmission 410 from the base station 402 and sends a UL transmission 408 to the base station 402. In an aspect, DL transmission 410 and UL transmission 408 may include MTC/IoT/BL control information or MTC/IoT/BL data. The UE406 receives a DL transmission 412 from the base station 402 and sends a UL transmission 414 to the base station 402. The communication between the UE404 and the base station 402 may include, for example, a cellular iot (ciot) Evolved Packet System (EPS) optimization procedure that includes early data transmission during a random access procedure without transitioning to an RRC connected state. The early data transmission may include UL and/or DL data.

Fig. 5 is an example call flow diagram 500 in accordance with aspects of the present disclosure. Referring to fig. 5, a call flow diagram 500 illustrates communications between a UE502, a base station 504, an MME506, and an SGW 508. The UE502 may include an NB-IoT UE, a BL UE, an eMTCUE, or a CE UE. In some aspects, the UE502 may be in an idle state 501 (e.g., RRC idle). At block 510, a resource determination may be made by the base station 504. The base station determines the resources to be used by the UE502 for the PRACH attempt. The PRACH resources determined at 510 may include PRACH resources associated with early data transmission, e.g., PRACH resources allocated for early data transfer without an RRC connection being established. For example, the base station may allow transmission of small data packet sizes (e.g., 10 bytes to 50 bytes) without establishing a full RRC connection. For example, the early data transmission may comprise a single data packet. The PRACH resources associated with early data transmissions may be different from those allocated by the base station for data transmissions after RRC connection establishment. In addition, the allocated PRACH resources may be different for different Coverage Enhancement (CE) levels. Thus, for early data transmission, the UE may select from a set of PRACH resources associated with early data transfer for the selected enhanced coverage level.

Enhanced early data Transfer (TX) modes may include data transfer in Msg1 (e.g., transfer with RACH preamble) or Msg3 (e.g., transfer after RAR), while other data transfer modes may require data to be transferred after RRC connection establishment.

The base station 504 may announce the allocated PRACH resources via System Information Broadcast (SIB) (512). As illustrated in fig. 5, the SIB may indicate a separate PRACH resource for early data transmission (e.g., data transfer prior to RRC connection establishment or without RRC connection establishment). In addition, the SIB announcement may also indicate a Transport Block Size (TBS) that can be used for early data transmission, which may be used by the UE to make a determination whether to use early data transmission.

At block 514, the UE502 selects PRACH/NPRACH resources based on the resources announced in the SIB and the amount of data to be transmitted. In some aspects, the resource selection may be based on a random selection or a dedicated allocation from a corresponding PRACH pool. The UE may indicate an intention to perform early data transfer to the network (e.g., base station 504) through the UE's selection of PRACH/NPRACH resources. For example, when a UE intends to transmit data before/without establishing an RRC connection with a base station, the UE may select PRACH resources from a separate pool allocated for enhanced early data transmission. The UE may determine whether to transmit data using enhanced early data transmission based on an amount of data to be transmitted to the base station. For example, when a UE has a single uplink packet to be transmitted to a base station (which can be adapted in a single MAC block transmission based on SIB announcement of TBS size), the UE may select from among PRACH resources allocated for early data transmission. Otherwise, the UE may select from among other PRACH resources. In another example, upon comparison to the information provided in the SIB, the UE may determine whether to perform an early data transmission based on the number of bytes of data to be transmitted. For example, the size may be limited to a single MAC block. For example, when the number of bytes is less than 50 bytes, the UE may select from among PRACH resources allocated for early data transmission. Otherwise, the UE may select from among other PRACH resources. Thus, the selection of PRACH resources may be based on the amount of data to be transmitted.

The UE502 transmits a PRACH preamble 516 as a first communication message to the base station 504 using the selected PRACH/NPRACH resources (516). In one example, the PRACH preamble may be referred to as Msg 1. The PRACH/NPRACH preamble selected by the UE may be based on PRACH resources associated with early data transmissions. In one example, the UE may include data in a first transmission to the base station. For example, Msg1 may optionally include a PRACH preamble and a NAS PDU.

The base station 504 sends (at 518) an RA response (RAR) to the UE in a second communication message that includes an uplink grant for the UE to perform early data transmission. In one example, the RAR may be referred to as Msg 2. In communications requiring establishment of an RRC connection prior to data transmission, the RAR may contain an uplink grant for transmission of an RRC connection setup/reestablishment/recovery message. The RAR may also include a Timing Advance (TA) (and temporary C-RNTI, etc.). To enable early data transmission prior to establishing the RRC connection, the RAR 518 may include an uplink grant for the early data transmission in addition to one or more of timing advance, temporary C-RNTI, power control information, and the like. If the power control information is not included, the UE502 may alternatively use open loop power control in which the UE determines the transmit power.

At 520, the UE502 may transmit data to the base station using the initial UL grant indicated in the RAR 518. In one example, the message may be referred to as an RRC early data request message. In another example, the message may be referred to as an RRC connectionless request. The payload may be included in a message 520 on the CCCH, e.g., as a CCCH SDU. The data may be transmitted on the control plane as NAS Protocol Data Units (PDUs). The transmission at 520 is performed during a random access procedure and without establishing an RRC connection. Transmission 520 is illustrated as a third communication message to base station 504 and may be referred to as Msg 3. The transmission 520 may further include a UE identification (UE id). In some aspects, the ue id may include a temporary mobile subscriber identity (e.g., system architecture evolution TMSI (S-TMSI)). In some aspects, the UE ID may include a resume ID if the UE has been previously suspended. As illustrated in fig. 5, the message 520 may also include an indication of the reason. The reason may indicate RRC connectionless mode. The cause may be referred to as a "cause code," and the code included in the message may indicate whether the message 520 includes data for transmission in RRC connectionless mode. The indication of the cause may also be referred to as an establishment cause. The UE502 may take into account power control information from the RAR (if included in the RAR). The UE502 may start a contention resolution timer after this step. For example, the contention resolution timer may be implemented using the controller/processor 359 of the example UE350 of fig. 3. The contention resolution timer value for early data transmissions may be different than the contention resolution timer value for communications that require establishment of an RRC connection prior to data transmission.

Message 520 may include data stored in a separate early data transfer buffer (which may be referred to as a Msg3 buffer, for example). The buffer may have a higher priority than the UL buffer used for transmission after the RRC connection.

In some aspects, the message 520 may further include an indication of RRC connectionless early UL data transmission. The indication may enable the base station 504 to distinguish between the UE requesting early data transmission before or after RRC connection establishment. As a result, the base station 504 may provide an additional message that includes a fast UL grant for connectionless UL transmissions (e.g., provide a UL grant to the UE without the UE transitioning to an RRC connected state). The UE may then respond with a data transfer without transitioning to the RRC connected state.

Further, in some aspects, the message 520 may include a NAS PDU and an indication that further UL data is pending at the UE. As such, the base station may respond to the message by providing further UL grants for transmissions using RRC connectionless mode.

At 522, the base station selects the MME506 based on the UE identification information (e.g., S-TMSI) in message 520 and forwards the NAS PDU to the MME 506. The base station 504 may also provide an indication to the MME506 that there is only one uplink NAS PDU. This may be done, for example, by including a cause code (e.g., "RRC connectionless mode") in the message 522 to the MME.

At 524, if DL data is available to the UE502, the SGW 508 provides the DL data to the MME506, and the MME506 forwards the DL data as a NAS PDU to the base station 504 to be delivered to the UE 502. If the base station 504 has indicated that there is only one ul NAS PDU, the MME506 may in response close the S1 application protocol (S1-AP) connection after forwarding any downlink NAS PDUs. As illustrated, the message 524 may include a DL NAS PDU and a release command. In addition, the base station indication for one UL NAS PDU may also be used by the MME506 to prioritize processing of UL data and to speed up or prioritize transmission of DL data by the SGW 508 to the MME 506.

At 526, base station 504 may transmit a message acknowledging receipt of the data in message 520. In one example, message 526 may be referred to as an RRC early data complete message. In another example, the message may be referred to as an RRC connectionless acknowledgement message. In some examples, the message may include a fourth message between the UE and the base station, and may be referred to as Msg 4. If the UE502 receives the message 526, the early data transmission may be considered successfully completed and the contention may be considered resolved. The message 526 may include a DL NAS PDU. If a NAS PDU is included, the NAS can confirm that it is communicating with a valid network. If DL data is included in the message 526, the UE may respond with HARQ 528 to include the received DL data. If the UE does not receive a response (e.g., a MAC level response) from the base station, the UE may retransmit message 520. Failure to receive the response within the contention resolution timer indicates a contention resolution failure, which results in the UE reattempting access from the idle state. Message 526 may only provide an acknowledgement of receipt of UL data if there is no DL data for the UE. After message 526 or message 528, the UE may continue in RRC idle state 530. Thus, UL data may be transmitted, for example, at 516 or 520 during the random access procedure without establishing an RRC connection and without the UE transitioning to an RRC connected state.

In some aspects, message 524 may be missing (e.g., the base station sends data to MME506, but for some reason MME506 does not respond). In such a case, the base station 504 may start a timer, for example, after the message 522. Upon expiration of the timer, base station 504 can proceed to message 526 with a positive ACK for successful receipt of message 520. In another example, the base station 504 can start a timer after the message 522. Upon expiration of such a timer, the base station 504 may proceed to message 526 with a positive ACK for successfully receiving the message 520, and with a further indication that the base station 504 failed to receive an ACK from the MME 506. In this example, the absence of a NAS PDU in message 524 may be indicated by the UE502 to the upper layers of the protocol stack. At 530, the UE returns to idle.

Further, in some aspects, instead of or in addition to acknowledging receipt of the NAS PDU from the base station 504, the MME506 may also indicate in message 524 that the UE502 is to transition from the idle state to the RRC connected state, rather than completing the RRC connectionless transmission session. In such a case, the S1-AP may not be immediately turned off, and the base station may send an indication to the UE502 to transition to an RRC connected state (e.g., RRC connection establishment) in message 526.

In the example call flow 500, a Dedicated Radio Bearer (DRB), as well as a Packet Data Convergence Protocol (PDCP) layer and a radio link control layer RLC, are not established for early data transmission. This is because early data transmission can be performed without establishing an RRC connection and instead using control plane RRC messaging. As such, the UE502 remains in an RRC _ IDLE state.

Fig. 6 is an example call flow diagram 600 in accordance with aspects of the present disclosure. Referring to fig. 6, a call flow diagram 600 illustrates communications between a UE602, a base station 604, an MME606, and an SGW 608. The UE602 may include an NB-IoT UE, a BL UE, an eMTC UE, or a CE UE. In some aspects, the UE602 may be in an idle state 601 (e.g., an RRC suspended state). At block 610, a resource determination may be made by a base station. The determination may be similar to the determination described in connection with 510 in fig. 5. For example, the base station 604 may allow transmission of a small data packet size (e.g., 10 bytes to 50 bytes) without establishing a full RRC connection (e.g., without the UE transitioning from an RRC suspended state to an RRC connected state during random access). The data transmission in fig. 6 may be performed on the user plane, and the data transmission in fig. 5 may be performed on the control plane. The base station may determine resources to be used by the UE602 for PRACH attempt. In some aspects, the base station 604 may allocate PRACH resources for this purpose. The PRACH resources determined at 610 may include PRACH resources associated with enhanced early data transmission, e.g., PRACH resources allocated for data transfer prior to RRC connection establishment or without RRC connection establishment. The PRACH resources allocated for early data transmission may be different from those allocated by the base station for data transmission after RRC connection establishment. In addition, the allocated PRACH resources may be different for different CE levels. Thus, for early data transmission, the UE may select from a set of PRACH resources associated with early data transfer for the selected enhanced coverage level.

In some aspects, the enhanced early data transmission may include a data transmission in Msg1 (e.g., a transmission with a RACH preamble) or Msg3 (e.g., a transmission after RAR), rather than being transmitted after RRC connection recovery is complete. The UE may indicate to the network (e.g., base station 604) the intention to perform early data transmission without resuming the RRC connection by selecting PRACH/NPRACH resources from a separate pool allocated for such RRC connectionless early data transfer. Base station 604 may announce the resource pool via a System Information Broadcast (SIB) (612).

At block 614, the UE602 selects PRACH/NPRACH resources based on the resources announced in the SIB and the amount of data to be transmitted. For example, if the size of the data to be transmitted satisfies the size limit received from the base station, the UE may select PRACH/NPRACH resources from a pool associated with early data transfer. As described in connection with the example in fig. 5, the UE may determine whether to transmit uplink data using RRC connectionless early data transmission based on the amount of data to be transmitted. Thus, if the size of the data exceeds the limit, the UE may select a different PRACH/NPRACH resource for performing random access. In some aspects, the resource selection may be based on a random selection or a dedicated allocation from a corresponding PRACH pool.

The UE602 transmits the selected PRACH/NPRACH preamble to the base station 604 in a first communication message (616). The first communication message may be referred to as Msg1 and may initiate an early data transfer. The PRACH/NPRACH preamble selected by the UE may be based on PRACH resources associated with early data transmissions. In one example, data for the early transmission may be included in a first message to the base station.

The base station 604 sends a RAR to the UE in a second communication message (e.g., which may be referred to as Msg2) (at 618). The RAR may contain an uplink grant for early data transmission. The RAR may also include timing advance (and temporary C-RNTI, etc.). To enable data transmission without the UE502 resuming the RRC connection, the RAR may also include power control information. Alternatively, the UE502 may use open loop power control (e.g., the UE decides the transmit power).

At 620, the UE602 may transmit data to the base station based on the uplink grant indicated in the RAR 618. This data may be included in a message 620 on the CCCH. Message 620 may be a third communication message destined for the base station and may be referred to as Msg 3. The data may be transmitted as data PDUs on the user plane. The transmission at 620 may be performed during a random access procedure and without resuming a previously suspended RRC connection. The message 620 may include a UE identifier. Since the UE is in the RRC suspended state 601, the UE identifier may include a resume ID of the UE. Because UE602 has been previously suspended, Msg3 may include a message similar to an RRC connection resume request that includes the UE's resume ID and includes application data. The message may also indicate a reason, for example, indicating an early data transmission as the reason for the message. This indication of the cause may be referred to as a "recovery cause" or an "establishment cause". For example, only a subset of the cause values may be applicable for early data transmission. Alternatively, a new recovery cause value may be defined for an earlier transmission of data in message 620. If the new cause value is signaled, the base station may forward the data to the MME606 without recovering RRC. Alternatively, a new message may be defined to carry a combination of unencrypted and encrypted payloads.

The UE602 can apply security to the data PDUs carried by the message 620. Thus, message 620 may also include an authentication token. Fig. 6 illustrates a message including an example authentication token referred to as a short recovery MAC-I. Authentication tokens may also be referred to by other names. Integrity may also be applied to the entire message 620. While in the RRC suspended state, the UE602 stores security keys for integrity that can be restored for use. In some aspects, the UE602 may also store keys for encryption. Thus, user data on both the uplink and downlink may be encrypted. The UE602 may be provided with a next hop chain count (NextHopChainingCount) and a resume ID during the suspension (e.g., provided from a previous session at 601 or provided with the next hop chain count and resume ID for the current session for the next session at 634).

In some aspects, a copy of the PDUs (e.g., data) may be left in the PDCP stack for possible duplicate transmission attempts in the event of a transmission failure of message 620.

The UE602 may also use security parameters based on the next hop chain count provided during the most recent suspension, e.g., in an RRC connection release message from a previous RRC connection (at 620). Thus, the data may be encrypted based on a count (such as a next hop chain count). The UE602 can cipher the data PDU and calculate the integrity key (e.g., over the entire RRC connectionless recovery request message). For example, in some aspects, an evolved node B base key (KeNB), an integrity key for RRC signaling (KRRCint), a ciphering key for RRC (KRRCenc), or other security parameters may be used for MAC calculation and optional ciphering. The security parameters may be based on information previously provided to the UE (e.g., during a previous suspension). The recovery ID, recovery cause, and short recovery MAC-I may be transmitted without encryption.

Base station 604 may optionally decode the RRC message, obtain the UE context and verify integrity, at block 622. If the integrity is successfully verified, the base station decrypts the data.

At 624, the base station transmits an S1-AP UE context resume request to the MME606, which S1-AP UE context resume request triggers the MME606 to resume the suspended connection. Thus, the base station initiates an S1-AP context restoration procedure to restore the S1 user plane external interface (S1-U) bearer. In some aspects, the base station 604 may signal to the MME606 that there is only one uplink NAS PDU. This may be done, for example, by including a cause code (e.g., "RRC connectionless mode"). This indication may also be used by MME606 to prioritize processing of UL data and to speed up or prioritize sending acknowledgements for recovery. At 626, the MME606 configures/restores the bearer, e.g., requests the S-GW to reactivate the S1-U bearer for the UE. At 628, the MME transmits an S1-AP UE context restoration response to the base station 604 to confirm configuration and restoration of the bearer, e.g., to confirm UE context restoration to the base station.

In some aspects, the UE context may be retrievable/unrecoverable (e.g., the base station is a new base station and there is no X2 interface). As such, at 628, the MME606 may indicate a failure in the context restoration response.

In some aspects, the UE context restoration response may be missing (e.g., the base station 604 sends a UE context restoration request to the MME, but the MME does not respond for various reasons). In such a case, the UE602 can revert to the full RRC connection by the base station 604 sending an indication to establish/resume the RRC connection.

At 630, the base station forwards the data PDU to the SGW 608. Similar to the example described in connection with fig. 5, if downlink data is available for the UE, the S-GW may send the downlink data to the base station after receiving uplink data at 630. As illustrated in fig. 6, the early data transmission may include a single uplink data transmission (e.g., 620). The early data transmission may also include a single downlink data transmission as described in connection with fig. 6.

If there is only one UL NAS PDU, at 632 the context of S1 may be released after the data has been forwarded. For example, when no further data is expected, the S1 connection may be suspended and the S1-U bearer may be deactivated. The UE may return to the RRC idle, suspended state. As illustrated, the base station may send a message 634 indicating early data transmission completion, and the UE may return to the RRC idle, suspended state 638. Message 634 may include a contention resolution message. Message 634 may be integrity protected and may include a count (such as a next hop chain count) and a recovery ID for the UE. The order of messages 630 and 634 may be adjusted such that an acknowledgement message 634 is sent to the UE before the base station forwards the data 630 to the SGW.

In some aspects, the UE602 may transmit HARQ after having passed AS security for received Access Stratum (AS) messages.

In some aspects, instead of or in addition to acknowledging receipt of the NAS PDU from the base station 606, the MME606 may also indicate that the UE602 is to transition from the idle state to the RRC connected state, rather than completing the RRC connectionless transport session. In such a case, the S1 context may not be released, may not be immediately turned off, and the base station may send an indication to the UE602 to transition to an RRC connected state (e.g., RRC connection establishment).

Fig. 7 is a flow chart 700 of a wireless communication method for early data transmission without an RRC connection to a base station. The UE may be in an RRC idle state as described in connection with fig. 5. Dashed lines are used to illustrate optional aspects. The method may be performed by a UE (e.g., UE 104, 350, 502, 602, equipment 802/802'). The UE may include an NB-IoTUE, BL UE, eMTC UE, or CE UE.

At 702, the UE receives SI from the base station. Fig. 5 and 6 illustrate examples of SI 512, 612 received by a UE. The SI may indicate PRACH resources to the UE. The PRACH resources may include a set of PRACH resources used for early data transmission (e.g., data transmitted without establishing an RRC connection). The SI may also indicate a maximum size of UL data that can be transmitted by using early data transmission. These indications may be separate for different CE levels of different NPRACH resources.

As illustrated at 704, the UE may select an RRC connected mode to transmit data communications, e.g., select between an active RRC connected transmission mode and an RRC connectionless transmission mode. The selection may be based on any of several factors, including the size of the data to be transmitted. At 706, the UE may send an indication of an RRC connected mode for sending the data communication to the base station. The indication may include a selection of PRACH resources from a PRACH resource pool associated with early data transfer. The PRACH resource may include NPRACH. The selected PRACH resources may also indicate an intention to perform connectionless early data transmission. The SI may be broadcast from the base station and may indicate PRACH resources associated with early data transmission in the event that the UE does not transition to the RRC connected state. The UE may select a resource based at least in part on an amount of data to be transmitted in the data communication.

The data communication may be transmitted to the base station during a random access procedure in which the UE does not establish an RRC connection. At 708, the UE may transmit a random access preamble to the base station. The random access preamble may be based on a selection from PRACH resources associated with early data transfer at 706. At 710, the UE may receive a grant for an uplink transmission without establishing an RRC connection.

At 712, the UE may transmit data communications to the base station over the control plane without establishing an RRC connection with the base station. At 712, the data communication may be transmitted to the base station based on the grant received at 710. The data communication includes data and an indication of a reason for the data communication. In some aspects, the cause indication may inform the base station to receive the data communication included in the message without establishing an RRC connection. For example, the cause indication may be referred to as a cause code, an establishment cause, and the like. In some aspects, the cause indication may indicate to the base station that the UE intends to perform early data transmission without establishing an RRC connection. The data communication may be transmitted on the CCCH (e.g., in a NAS message). Thus, the data communication can be transmitted to the base station without the UE transitioning to the RRC connected state. The data communication may include a single uplink data transmission. The size of the data included in a single uplink data transmission may be less than the size limit indicated by the base station. The data may include NAS PDUs transmitted on the control plane, as described in connection with fig. 5.

The data communication may also include UE identity information, e.g., S-TMSI for the UE.

The early data transfer may further include a small amount of downlink data received from the network. Thus, at 714, the UE may receive downlink data communications from the base station over the control plane without establishing an RRC connection with the base station. The downlink data communication may be received in an RRC message indicating early data transfer completion. The UE may receive a single downlink data transmission, e.g., as illustrated in fig. 5. Additional aspects described in connection with fig. 5 or 6 may be performed by the UE in connection with the method of fig. 7. The UE may continue in the RRC idle state after transmitting and/or receiving the early data transmission.

Fig. 8 is a conceptual data flow diagram 800 illustrating the data flow between different devices/components in an example apparatus 802. The apparatus may be a UE (e.g., UE 104, 350, 502, 602). The UE may include an NB-IoT UE, a BL UE, an eMTC UE, or a CE UE, among others. The apparatus includes a receiving component 804 for receiving downlink communications from a base station 850, and a transmitting component 806 for transmitting uplink communications to the base station 850. The apparatus comprises a system information component 808 that receives system information from a base station 850, and a data communication component 810 that transmits a data communication to the base station on a control plane without establishing an RRC connection with the base station, wherein the data communication comprises data and an indication of a reason for the data communication. The apparatus can include an RRC mode component 812 for selecting an RRC connected mode to communicate data communications, and an indication component 814 for sending an indication of the RRC connected mode to send the data communications to a base station. The indication may be based on PRACH resources associated with early data transfer. The apparatus can include a preamble component 816 for transmitting a random access preamble to a base station. The apparatus may include a RAR component 818 for receiving a RAR from a base station, the RAR may include a grant for an uplink transmission without establishing an RRC connection. The apparatus can include a downlink data component 820 for receiving downlink data communications from a base station over a control plane without establishing an RRC connection with the base station.

The apparatus may include additional components that perform each block of the algorithm in the aforementioned flow diagrams of fig. 5, 6, and 7. As such, each block in the aforementioned flow diagrams of fig. 5, 6, and 7 may be performed by a component and the apparatus may include one or more of those components. These components may be one or more hardware components specifically configured to perform the described processes/algorithms, implemented by a processor configured to perform the described processes/algorithms, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 9 is a diagram 900 illustrating an example of a hardware implementation of an apparatus 902' employing a processing system 914. The processing system 914 may be implemented with a bus architecture, represented generally by the bus 924. The bus 924 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 914 and the overall design constraints. The bus 924 links together various circuits including one or more processors and/or hardware components (represented by the processor 904, the components 804, 806, 808, 810, 812, 814, 816, 818, 820, and the computer-readable medium/memory 906). The bus 924 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 914 may be coupled to the transceiver 910. The transceiver 910 is coupled to one or more antennas 920. The transceiver 910 provides a means for communicating with various other apparatus over a transmission medium. Transceiver 910 receives a signal from one or more antennas 920, extracts information from the received signal, and provides the extracted information to processing system 914 (and in particular, to receiving component 804). In addition, transceiver 910 receives information from processing system 914 (and in particular transmission component 810) and generates a signal to be applied to one or more antennas 920 based on the received information. The processing system 914 includes a processor 904 coupled to a computer-readable medium/memory 906. The processor 904 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 906. The software, when executed by the processor 904, causes the processing system 914 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 906 may also be used for storing data that is manipulated by the processor 904 when executing software. Processing system 914 further includes at least one of components 804, 806, 808, 810, 812, 814, 816, 818, 820. These components may be software components running in the processor 904, resident/stored in the computer readable medium/memory 906, one or more hardware components coupled to the processor 904, or some combination thereof. Processing system 914 can be a component of base station 310 and can include memory 376 and/or at least one of the following: TX processor 316, RX processor 370, and controller/processor 375. The processing system 914 may be a component of the UE350 and may include the memory 360 and/or at least one of: TX processor 368, RX processor 356, and controller/processor 359.

In one configuration, the apparatus 802/802' for wireless communication includes: means for receiving system information from a base station; means for transmitting a data communication to the base station on a control plane without establishing an RRC connection with the base station, wherein the data communication includes data and an indication of a cause for the data communication, means for selecting an RRC connected mode for transmitting the data communication, means for sending an indication of the RRC connected mode for sending the data communication to the base station, means for transmitting a random access preamble to the base station, means for receiving a grant for an uplink transmission without establishing an RRC connection, wherein the data communication is transmitted to the base station based on the grant; and means for receiving downlink data communications from the base station without establishing an RRC connection with the base station. The aforementioned means may be the aforementioned component of the apparatus 802 and/or one or more components of the processing system 914 of the apparatus 802' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 914 may include the TX processor 368, the RX processor 356, and the controller/processor 359. As such, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller/processor 359 configured to perform the functions recited by the aforementioned means.

Fig. 10 is a flow chart 1000 of a wireless communication method for early data reception without RRC connection to a UE. The method may be performed by a base station (e.g., base station 102, 180, 310, 504, 604, 850, apparatus 1102, 1102'). Dashed lines are used to illustrate optional aspects.

At 1002, the base station indicates resources in system information. Fig. 5 and 6 illustrate examples of SIs 512, 612 transmitted by a base station. The SI may indicate PRACH resources to the UE. The PRACH resources may include a set of PRACH resources used for early data transmission (e.g., data transmitted without establishing an RRC connection). The SI may also indicate a maximum size of UL data that can be transmitted by using early data transmission. These indications may be separated by different CE levels corresponding to different NPRACH resources.

At 1012, the base station receives a data communication from the UE without establishing an RRC connection with the UE, wherein the data communication includes data and a cause indication. The cause indication may inform the base station to receive the data communication included in the RRC connection resume message without resuming the RRC connection. For example, the cause indication may be referred to as a cause code, an establishment cause, and the like. The reason indication may indicate to the base station that the UE intends to perform early data transmission without establishing an RRC connection. The data communication may be included in an RRC message indicating an intention to perform a connectionless early data transfer. The data communication may be received on the CCCH (e.g., in a NAS message). Thus, at 1014, the data communication can be received from the UE and forwarded to the core network component without establishing an RRC connected state with the UE (e.g., without the UE transitioning to an RRC connected state). The data communication may include a single uplink data transmission. The data may include NAS PDUs received at the control plane, as described in connection with fig. 5. The data may comprise data PDUs received on the user plane, as described in connection with fig. 6.

The data communication may further include UE identity information, e.g., including S-TMSI when data is received on the control plane, or including a recovery ID for the UE when data is received on the user plane. The data communication may further include an authentication token, for example, when the data is received on the user plane. The data may be received on the user plane, e.g., when the UE starts from an RRC idle, suspended state. In this example, the data communication may be received in an RRC connection resume message, and the cause indication may inform the base station to receive the data communication included in the RRC connection resume message without resuming the RRC connection. The data communication may further include an authentication token.

The data communication may be received from the UE during a random access procedure, as illustrated in the examples in fig. 5 and 6. For example, at 1006, the base station may receive a random access preamble from the UE based on PRACH resources (e.g., NPRACH resources) associated with early data transfer. Different resources may be associated with different CE levels. In response, at 1008, the base station may transmit a RAR to the UE that includes an uplink grant for early data transmission without establishing an RRC connection with the UE. Subsequently, at 1012, the data communication may be received from the UE based on the uplink grant.

The early data transfer may further include a small amount of downlink data transmitted to the UE. Thus, at 1016, the base station can transmit downlink data communications from the base station without establishing an RRC connection with the UE. The downlink data communication may be transmitted to the UE in an RRC message indicating early data transfer completion to the UE. The base station may transmit a single downlink data transmission, e.g., as illustrated in fig. 5. Additional aspects described in connection with fig. 5 or 6 may be performed by a base station in connection with the method of fig. 10.

Fig. 11 is a conceptual data flow diagram 1100 illustrating the data flow between different apparatuses/components in an exemplary apparatus 1102. The apparatus may be a base station (e.g., base stations 102, 180, 310, 504, 604, 850). The apparatus includes a receiving component 1104 for receiving uplink communications from a UE1150, and a downlink component 1106 for transmitting downlink communications to the UE and/or for communicating with a core network 1155. The apparatus includes an SI component 1108 for indicating resources in system information; and a data communication component 1110 for receiving a data communication from the UE without establishing an RRC connection with the UE, wherein the data communication includes the data and a cause indication. The apparatus may include a preamble component 1112 for receiving a random access preamble from a UE based on PRACH resources associated with early data transfer, and a RAR component 1114 for transmitting a random access response to the UE including an uplink grant for an early data transmission without establishing an RRC connection with the UE. The apparatus may include a core network component 1116 for forwarding data to a core network without establishing an RRC connection with the UE. The apparatus may include a downlink data component 1118 for transmitting downlink data communications to the UE without establishing an RRC connection with the UE.

The apparatus may include additional components that perform each block of the algorithm in the aforementioned flow diagrams of fig. 5, 6, and 10. As such, each block in the aforementioned flow diagrams of fig. 5, 6, and 10 may be performed by a component and the apparatus may include one or more of those components. These components may be one or more hardware components specifically configured to perform the described processes/algorithms, implemented by a processor configured to perform the described processes/algorithms, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 12 is a diagram 1200 illustrating an example of a hardware implementation of an apparatus 1102' employing a processing system 1214. The processing system 1214 may be implemented with a bus architecture, represented generally by the bus 1224. The bus 1224 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1214 and the overall design constraints. The bus 1224 links together various circuits including one or more processors and/or hardware components (represented by the processor 1204, the components 1104, 1106, 1108, 1110, 1112, 1114, 1116, 1118, and the computer-readable medium/memory 1206). The bus 1224 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1214 may be coupled to a transceiver 1210. The transceiver 1210 is coupled to one or more antennas 1220. The transceiver 1210 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1210 receives a signal from the one or more antennas 1220, extracts information from the received signal, and provides the extracted information to the processing system 1214, and in particular the receiving component 1104. Additionally, the transceiver 1210 receives information from the processing system 1214 (and in particular the transmission component 1106) and generates a signal to be applied to the one or more antennas 1220 based on the received information. The processing system 1214 includes a processor 1204 coupled to a computer-readable medium/memory 1206. The processor 1204 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1206. The software, when executed by the processor 1204, causes the processing system 1214 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1206 may also be used for storing data that is manipulated by the processor 1204 when executing software. The processing system 1214 further includes at least one of the components 1104, 1106, 1108, 1110, 1112, 1114, 1116, 1118. These components may be software components running in the processor 1204, resident/stored in the computer readable medium/memory 1206, one or more hardware components coupled to the processor 1204, or some combination thereof. The processing system 1214 may be a component of the base station 310 and may include the memory 376 and/or at least one of the following: TX processor 316, RX processor 370, and controller/processor 375.

In one configuration, the apparatus 1102/1102' for wireless communication includes: the apparatus generally includes means for indicating resources in system information, means for receiving a data communication from a UE without establishing an RRC connection with the UE, wherein the data communication includes data and a cause indication, means for receiving a random access preamble from the UE based on PRACH resources associated with early data transfer, means for transmitting a random access response to the UE, the random access response including an uplink grant for early data transmission without establishing the RRC connection with the UE, means for forwarding the data to a core network without establishing the RRC connection with the UE, and means for transmitting a downlink data communication to the UE without establishing the RRC connection with the UE. The aforementioned means may be the aforementioned components of the apparatus 1102 and/or one or more components of the processing system 1214 of the apparatus 1102' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1214 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 13 is a flow diagram 1300 of a wireless communication method for early data transmission without restoring RRC connection to a base station. For example, the UE may be in an RRC suspended state, e.g., as described in connection with fig. 6. Dashed lines are used to illustrate optional aspects. The method may be performed by a UE (e.g., UE 104, 350, 502, 602, equipment 1402/1402'). The UE may include an NB-IoT UE, a BL UE, an eMTC UE, or a CE UE.

At 1302, the UE receives SI from the base station. Fig. 6 illustrates an example of SI 612 received by a UE. The SI may indicate PRACH resources to the UE. The PRACH resources may include a set of PRACH resources used for early data transmission (e.g., data transmitted without resuming an RRC connection). The SI may also indicate the maximum size of UL data that can be transmitted without resuming the RRC connection, e.g., by using early data transmission on the user plane. These indications may be separate for different CE levels of different NPRACH resources.

As illustrated at 1304, the UE may select an RRC connected mode in which to communicate data communications, e.g., between an active RRC connected transmission mode and an RRC connectionless transmission mode in which the UE does not resume an RRC connection. The selection may be based on any of several factors, including the size of the data to be transmitted. At 1306, the UE may send an indication to the base station of an RRC connected mode for sending the data communication. The indication may include a selection of PRACH resources from a PRACH resource pool associated with early data transfer. The PRACH resource may include NPRACH. The selected PRACH resources may also indicate an intention to perform connectionless early data transmission. The SI may be broadcast from the base station and may indicate PRACH resources associated with early data transmission in the event that the UE does not transition to the RRC connected state. The UE may select a resource based at least in part on an amount of data to be transmitted in the data communication.

The data communication may be transmitted to the base station during a random access procedure in which the UE does not resume the RRC connection. At 1308, the UE may transmit a random access preamble to the base station. The random access preamble may be based on a selection at 1306 from PRACH resources associated with early data transfer. At 1310, the UE may receive a grant for an uplink transmission without resuming the RRC connection.

At 1312, the UE may transmit data communications to the base station on a user plane without resuming the RRC connection with the base station. At 1312, the data communication may be transmitted to the base station based on the grant received at 1310. The data communication may include data as well as a cause indication. The data communication may comprise an RRC message. For example, the data may be multiplexed in, e.g., the same transmission along with the RRC message. This may be contrasted with the example in fig. 7, where the data is included in an RRC message and sent on the control plane. In an example, the cause indication may be included in an RRC message. In another example, the cause indication may be separate from the RRC message, but still included in the same data communication transmission. The RRC message may include an RRC connection recovery request along with a reason indication for the data communication. The data communication may also include a UE ID, which may be included in the RRC message. Thus, user data may be multiplexed with RRC messages including a cause indication and/or UE ID and sent together in the same transmission on the user plane. In another example, the data and the cause may be included in an RRC message. In some aspects, the data may be transmitted with an RRC connection recovery message, and the cause indication may inform the base station to receive the data multiplexed with the RRC connection recovery message without recovering the RRC connection. For example, the cause indication may be referred to as a cause code, a recovery cause, and the like. The data communication may be transmitted on the CCCH (e.g., in a NAS message). Thus, the data communication can be transmitted to the base station without the UE transitioning to the RRC connected state. The data communication may include a single uplink data transmission. The size of the data included in a single uplink data transmission may be less than or equal to the size limit indicated by the base station. The data may comprise data PDUs transmitted on the user plane, as described in connection with fig. 6.

The data communication may further include UE identity information (e.g., a recovery ID included in the RRC message) for the UE to transmit data on the user plane. The data communication may further include an authentication token. The data may be transmitted on the user plane, e.g., while the UE is in an RRC idle, suspended state.

The early data transfer may further include a small amount of downlink data received from the network. Thus, at 1314, the UE can receive downlink data communications from the base station over the user plane without resuming the RRC connection with the base station. The downlink data communication may include an RRC message indicating early data transfer completion. The UE may receive a single downlink data transmission, e.g., as illustrated in fig. 6. Additional aspects described in connection with fig. 5 or 6 may be performed by the UE in connection with the method of fig. 13. The UE may remain in an RRC idle, suspended state after transmitting and/or receiving early data transmissions.

Fig. 14 is a conceptual data flow diagram 1400 illustrating the data flow between different devices/components in an example apparatus 1402. The equipment may be a UE (e.g., UE 104, 350, 502, 602) in an RRC suspended state with the base station 1450. The UE may include an NB-IoT UE, a BL UE, an eMTC UE, or a CE UE, among others. The apparatus includes a receiving component 1404 for receiving downlink communications from the base station 1450, and a transmitting component 1406 for transmitting uplink communications to the base station 1450. The apparatus includes a system information component 1408 for receiving system information from a base station 1450, and a data communication component 1410 for transmitting a data communication to the base station on a user plane without resuming an RRC connection with the base station, wherein the data communication includes data and an indication of a reason for the data communication. The apparatus can include an RRC mode component 1412 for selecting an RRC connected mode to communicate the data communication, and an indication component 1414 for sending an indication of the RRC connected mode for sending the data communication to the base station. The indication may be based on PRACH resources associated with early data transfer. The apparatus may include a preamble component 1416 for transmitting a random access preamble to a base station. The apparatus may include a RAR component 1418 for receiving a RAR from a base station, the RAR may include a grant for an uplink transmission without resuming an RRC connection. The apparatus may include a downlink data component 1420 for receiving downlink data communications from a base station on a user plane without establishing an RRC connection with the base station. The apparatus may further include a token component 1422 configured to include the authentication token with the data transmitted to the base station.

The apparatus may include additional components to perform each block of the algorithm in fig. 6, 13 and the aforementioned flow charts of fig. 5 and 7. As such, each block in the aforementioned flow diagrams of fig. 5, 6, 7, and 13 may be performed by a component and the apparatus may include one or more of those components. These components may be one or more hardware components specifically configured to perform the described processes/algorithms, implemented by a processor configured to perform the described processes/algorithms, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 15 is a diagram 1500 illustrating an example of a hardware implementation of an apparatus 1402' employing a processing system 1514. The processing system 1514 may be implemented with a bus architecture, represented generally by the bus 1524. The bus 1524 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1514 and the overall design constraints. The bus 1524 links together various circuits that include one or more processors and/or hardware components, represented by the processor 1504, the components 1404, 1406, 1408, 1410, 1412, 1414, 1416, 1418, 1420, 1422, and the computer-readable medium/memory 1506. The bus 1524 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1514 may be coupled to a transceiver 1510. The transceiver 1510 is coupled to one or more antennas 1520. The transceiver 1510 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1510 receives a signal from the one or more antennas 1520, extracts information from the received signal, and provides the extracted information to the processing system 1514 (and in particular, the receiving component 1404). Additionally, the transceiver 1510 receives information from the processing system 1514 (and in particular the transmission component 1410) and generates signals to be applied to one or more antennas 1520 based on the received information. The processing system 1514 includes a processor 1504 coupled to a computer-readable medium/memory 1506. The processor 1504 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1506. The software, when executed by the processor 1504, causes the processing system 1514 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1506 may also be used for storing data that is manipulated by the processor 1504 when executing software. The processing system 1514 further includes at least one of the components 1404, 1406, 1408, 1410, 1412, 1414, 1416, 1418, 1420, 1422. These components may be software components running in the processor 1504, resident/stored in the computer readable medium/memory 1506, one or more hardware components coupled to the processor 1504, or some combination thereof. The processing system 1514 may be a component of the base station 310 and may include memory 376 and/or at least one of: TX processor 316, RX processor 370, and controller/processor 375. The processing system 1514 may be a component of the UE350 and may include the memory 360 and/or at least one of: TX processor 368, RX processor 356, and controller/processor 359.

In one configuration, the apparatus 1402/1402' for wireless communication includes: means for receiving system information from a base station while in an RRC suspended state, means for transmitting data communications to the base station on a user plane without resuming an RRC connection with the base station, wherein the data communication includes data and an indication of a cause of the data communication, means for selecting an RRC connected mode for communicating the data communication, means for transmitting an indication of an RRC connected mode used to transmit the data communication to the base station, means for transmitting a random access preamble to the base station, means for receiving a grant for an uplink transmission without recovering an RRC connection, wherein the data communication is transmitted to the base station based on the grant, and means for receiving a downlink data communication from the base station on the user plane without restoring the RRC connection with the base station. The aforementioned means may be the aforementioned components of the apparatus 1402 and/or one or more components of the processing system 1514 of the apparatus 1402' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1514 may include the TX processor 368, the RX processor 356, and the controller/processor 359. As such, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller/processor 359 configured to perform the functions recited by the aforementioned means.

Fig. 16 is a flow chart 1600 of a wireless communication method for early data reception without restoration of RRC connection to the UE. The method may be performed by a base station (e.g., base station 102, 180, 310, 504, 604, 850, apparatus 1702, 1702'). The base station may be in an RRC suspended state as described in connection with fig. 6. Dashed lines are used to illustrate optional aspects.

At 1602, the base station indicates resources in system information. Fig. 6 illustrates an example of SI 612 transmitted by a base station. The SI may indicate PRACH resources to the UE. The PRACH resources may include a set of PRACH resources used for early data transmission (e.g., data transmitted without establishing an RRC connection). The SI may also indicate a maximum size of UL data that may be transmitted by using early data transmission. These indications may be separated by different CE levels corresponding to different NPRACH resources.

At 1612, the base station receives a data communication from the UE on a user plane without restoring the RRC connection with the UE, wherein the data communication includes the data and the cause indication. The data communication may comprise an RRC message. For example, the data may be multiplexed in, e.g., the same transmission along with the RRC message. In an example, the cause indication can be included in the RRC message. In another example, the cause indication may be separate from the RRC message, but still included in the same data communication transmission. The RRC message may include an RRC connection recovery request along with a reason indication for the data communication. The data communication may also include a UE ID, which may be included in the RRC message, for example. Thus, user data may be multiplexed with RRC messages including a cause indication and/or UE ID and sent together in the same transmission on the user plane. In another example, the data and the cause may be included in an RRC message. The cause indication may inform the base station to receive data multiplexed with the RRC connection recovery message without recovering the RRC connection. For example, the cause indication may be referred to as a cause code, a recovery cause, and the like. The reason indication may indicate to the base station that the UE intends to perform early data transmission without resuming the RRC connection. The data may be sent (e.g., multiplexed) in a single transmission with an RRC message indicating an intention to perform a connectionless early data transmission (e.g., without recovering the RRC connection). The data communication may be received on the CCCH (e.g., in a data PDU). Thus, at 1614, the data may be received from the UE and forwarded to the core network component without resuming the RRC connected state with the UE (e.g., without the UE transitioning from the RRC suspended state to the RRC connected state). The data communication may include a single uplink data transmission. The data may comprise data PDUs received on the user plane, as described in connection with fig. 6.

The data communication (e.g., RRC message) may further include UE identity information, e.g., a recovery ID for the UE. The data communication may further include an authentication token, as illustrated in message 620 in fig. 6. The data may be received on the user plane, e.g., while the UE is in an RRC idle, suspended state. In this example, the data communication may include an RRC connection recovery message, and the cause indication may inform the base station to receive data included with the RRC connection recovery message in the data communication without recovering the RRC connection. The data communication may further include an authentication token.

The data communication may be received from the UE during a random access procedure, as illustrated in the examples in both fig. 5 and 6. For example, at 1606, the base station may receive a random access preamble from the UE based on PRACH resources (e.g., NPRACH resources) associated with early data delivery. Different PRACH resources may be associated with different CE levels. In response, at 1608, the base station may transmit a RAR to the UE that includes an uplink grant for early data transmission without restoring the RRC connection with the UE. Subsequently, at 1612, the data communication can be received from the UE based on the uplink grant. Fig. 6 illustrates an example message 620 as a transmission.

The early data transfer may further include a small amount of downlink data transmitted to the UE. Thus, at 1616, the base station may transmit downlink data communications from the base station over the user plane without establishing an RRC connection with the UE. The downlink data communication may be transmitted to the UE in an RRC message indicating early data transfer completion to the UE. The base station may transmit a single downlink data transmission, e.g., as illustrated in fig. 6. Additional aspects described in connection with fig. 5 or 6 may be performed by a base station in connection with the method of fig. 16.

Fig. 17 is a conceptual data flow diagram 1700 illustrating the data flow between different apparatuses/components in an exemplary apparatus 1702. The apparatus may be a base station (e.g., base stations 102, 180, 310, 504, 604, 850). The apparatus includes a receiving component 1704 for receiving uplink communications from a UE1750 and a downlink component 1706 for transmitting downlink communications to the UE and/or for communicating with a core network 1755. The apparatus includes an SI component 1708 for indicating resources in system information, and a data communication component 1710 for receiving data communication from a UE on a user plane without resuming an RRC connection with the UE, wherein the data communication includes data and a cause indication. The data communication may be included in Msg3 from the UE. The apparatus may include a preamble component 1712 for receiving a random access preamble from a UE based on PRACH resources associated with early data transfer, and a RAR component 1714 for transmitting a random access response to the UE, the random access response including an uplink grant for early data transmission without resuming an RRC connection with the UE. The apparatus may include a core network component 1716 to forward data to the core network without resuming an RRC connection with the UE. The apparatus can include a downlink data component 1718 for transmitting downlink data communications to the UE on a user plane without resuming an RRC connection with the UE. The apparatus may include a token component 1720 for authenticating the UE based on an authentication token included in the data communication.

The apparatus may include additional components that perform each block of the algorithm in the aforementioned flow diagrams of fig. 5, 6 and 10, and 16. As such, each block in the aforementioned flow diagrams of fig. 5, 6 and 10, and 16 may be performed by a component and the apparatus may include one or more of those components. These components may be one or more hardware components specifically configured to perform the described processes/algorithms, implemented by a processor configured to perform the described processes/algorithms, stored in a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 18 is a diagram 1800 illustrating an example of a hardware implementation of an apparatus 1702' employing a processing system 1814. The processing system 1814 may be implemented with a bus architecture, represented generally by the bus 1824. The bus 1824 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1814 and the overall design constraints. The bus 1824 links together various circuits including one or more processors and/or hardware components (represented by the processor 1804, the components 1704, 1706, 1708, 1710, 1712, 1714, 1716, 1718, 1720, and the computer-readable medium/memory 1806). The bus 1824 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1814 may be coupled to a transceiver 1810. The transceiver 1810 is coupled to one or more antennas 1820. The transceiver 1810 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1810 receives a signal from the one or more antennas 1820, extracts information from the received signal, and provides the extracted information to the processing system 1814 (and in particular the receive component 1704). Additionally, transceiver 1810 receives information from processing system 1814 (and in particular transmission component 1706) and generates a signal to be applied to one or more antennas 1820 based on the received information. The processing system 1814 includes a processor 1804 coupled to a computer-readable medium/memory 1806. The processor 1804 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1806. The software, when executed by the processor 1804, causes the processing system 1814 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1806 may also be used for storing data that is manipulated by the processor 1804 when executing software. The processing system 1814 further includes at least one of the components 1704, 1706, 1708, 1710, 1712, 1714, 1716, 1718, 1720. These components may be software components running in the processor 1804, resident/stored in the computer readable medium/memory 1806, one or more hardware components coupled to the processor 1804, or some combination thereof. The processing system 1814 may be a component of the base station 310 and may include the memory 376 and/or at least one of: TX processor 316, RX processor 370, and controller/processor 375.

In one configuration, the apparatus 1702/1702' for wireless communication includes: means for indicating resources in system information, means for receiving data communication from a UE on a user plane without resuming an RRC connection with the UE, wherein the data communication includes data and a cause indication; means for receiving a random access preamble from the UE based on PRACH resources associated with early data transmission; means for forwarding the data to a core network without resuming the RRC connection with the UE; and means for transmitting downlink data communications to the UE on the user plane without resuming the RRC connection with the UE. The aforementioned means may be the aforementioned components of apparatus 1702 and/or one or more components of processing system 1814 of apparatus 1702' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1814 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

It should be understood that the specific order or hierarchy of blocks in the processes/flow diagrams disclosed is an illustration of example approaches. It will be appreciated that the specific order or hierarchy of blocks in the processes/flow diagrams may be rearranged based on design preferences. 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 term "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. The term "a" or "an" refers to one or more, unless specifically stated otherwise. 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 a plurality of a, B, or C. In particular, 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, A and B, A and C, B and C only, 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 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 terms "module," mechanism, "" element, "" device, "and the like may not be a substitute for the term" means. As such, no claim element should be construed as a means-plus-function unless the element is explicitly recited using the phrase "means for … …".

Claims (57)

1. A method of wireless communication by a User Equipment (UE) without a Radio Resource Control (RRC) connection to a base station, comprising:

receiving system information from the base station; and

transmitting, by a UE, data communications to the base station on a control plane without establishing the RRC connection with the base station,

wherein the data communication comprises data and an indication of a reason for the data communication.

2. The method of claim 1, wherein the data communication is transmitted to the base station during a random access procedure.

3. The method of claim 1, wherein the data communication further comprises UE identity information.

4. The method of claim 3, wherein the UE identity information comprises a system architecture evolution (TMSI) (S-TMSI) for the UE.

5. The method of claim 1, wherein the data communication is included in an RRC message indicating an intention to perform an RRC connectionless early data transmission.

6. The method of claim 1, wherein the data communication is transmitted in a non-access stratum (NAS) message on a Common Control Channel (CCCH).

7. The method of claim 1, wherein the data communication is transmitted to the base station without the UE transitioning to an RRC connected state.

8. The method of claim 1, wherein the data communication comprises a single uplink data transmission.

9. The method of claim 8, wherein a size of the data included in the single uplink data transmission is less than a size limit indicated by the base station.

10. The method of claim 1, further comprising:

selecting, by the UE, an RRC connected mode to transmit the data communication, wherein the RRC connected mode is an active RRC connected transport mode or an RRC connectionless transport mode.

11. The method of claim 1, further comprising:

transmitting an RRC mode indication of an RRC connected mode used to transmit the data communication to the base station.

12. The method of claim 11, wherein the RRC mode indication comprises a selection of a Physical Random Access Channel (PRACH) resource from a PRACH resource pool associated with early data transmissions.

13. The method of claim 12, wherein the PRACH resource comprises a narrowband PRACH (nprach).

14. The method of claim 1, further comprising:

transmitting a random access preamble to the base station; and

receiving a grant for an uplink transmission without establishing the RRC connection, wherein the data communication is transmitted to the base station based on the grant.

15. The method of claim 1, wherein the system information is broadcast from the base station and indicates Physical Random Access Channel (PRACH) resources associated with early data transmission without the UE transitioning to an RRC connected state.

16. The method of claim 15, wherein the UE selects resources based at least in part on an amount of data to be transmitted in the data communication.

17. The method of claim 1, further comprising:

receiving downlink data communications from the base station over the control plane without establishing the RRC connection with the base station.

18. The method of claim 17, wherein the downlink data communication is received in an RRC message indicating early data transfer completion.

19. An apparatus for wireless communications by a User Equipment (UE) without a Radio Resource Control (RRC) connection to a base station, comprising:

means for receiving system information from the base station; and

means for transmitting, by a UE, data communications to the base station on a control plane without establishing the RRC connection with the base station,

wherein the data communication comprises data and an indication of a reason for the data communication.

20. The apparatus of claim 19, wherein the data communication is transmitted to the base station during a random access procedure.

21. The apparatus of claim 19, further comprising:

means for selecting, by the UE, an RRC connected mode to transmit the data communication, wherein the RRC connected mode is an active RRC connected transport mode or an RRC connectionless transport mode.

22. The apparatus of claim 19, further comprising:

means for transmitting an RRC mode indication of an RRC connected mode used to transmit the data communication to the base station.

23. The apparatus of claim 19, further comprising:

means for transmitting a random access preamble to the base station; and

means for receiving a grant for an uplink transmission without establishing the RRC connection, wherein the data communication is transmitted to the base station based on the grant.

24. The apparatus of claim 19, further comprising:

means for receiving downlink data communications from the base station on the control plane without establishing the RRC connection with the base station.

25. An apparatus for wireless communications by a User Equipment (UE) without a Radio Resource Control (RRC) connection to a base station, comprising:

a memory; and

at least one processor coupled to the memory and configured to:

receiving system information from the base station; and

transmitting, by a UE, data communications to the base station on a control plane without establishing the RRC connection with the base station,

wherein the data communication comprises data and an indication of a reason for the data communication.

26. The apparatus of claim 25, wherein the data communication is transmitted to the base station during a random access procedure.

27. The apparatus of claim 25, wherein the at least one processor is further configured to:

selecting, by the UE, an RRC connected mode to transmit the data communication, wherein the RRC connected mode is an active RRC connected transport mode or an RRC connectionless transport mode.

28. The apparatus of claim 25, wherein the at least one processor is further configured to:

transmitting an RRC mode indication of an RRC connected mode used to transmit the data communication to the base station.

29. The apparatus of claim 25, wherein the at least one processor is further configured to:

transmitting a random access preamble to the base station; and

receiving a grant for an uplink transmission without establishing the RRC connection, wherein the data communication is transmitted to the base station based on the grant.

30. The apparatus of claim 25, wherein the at least one processor is further configured to:

receiving downlink data communications from the base station over the control plane without establishing the RRC connection with the base station.

31. A computer-readable medium storing computer executable code for wireless communications by a User Equipment (UE) without a Radio Resource Control (RRC) connection to a base station, comprising code to:

receiving system information from the base station; and

transmitting, by a UE, data communications to the base station on a control plane without establishing the RRC connection with the base station,

wherein the data communication comprises data and an indication of a reason for the data communication.

32. The computer-readable medium of claim 31, wherein the data communication is transmitted to the base station during a random access procedure.

33. A method of wireless communication by a base station without a Radio Resource Control (RRC) connection to a User Equipment (UE), comprising:

indicating a resource in the system information; and

receiving data communication on a control plane from the UE without establishing the RRC connection with the UE,

wherein the data communication comprises data and a cause indication.

34. The method of claim 33, wherein the data communication is received from the UE during a random access procedure.

35. The method of claim 33, wherein the data communication is included in Msg3 from the UE.

36. The method of claim 33, wherein the data communication further comprises UE identity information, and wherein the UE identity information comprises a system architecture evolution, TMSI (S-TMSI), for the UE.

37. The method of claim 33, wherein the data communication is included in an RRC message, and the cause indication indicates an intention to perform an RRC connectionless early data transmission.

38. The method of claim 33, wherein the data communication is received in a non-access stratum (NAS) message on a Common Control Channel (CCCH).

39. The method of claim 33, wherein the data communication is received from the UE and forwarded to a core network component without establishing an RRC connected state with the UE.

40. The method of claim 33, wherein the data communication comprises a single uplink data transmission.

41. The method of claim 33, wherein the resources indicated in the system information comprise Physical Random Access Channel (PRACH) resources associated with early data transmissions.

42. The method of claim 41, wherein the PRACH resource comprises a Narrowband PRACH (NPRACH).

43. The method of claim 42, wherein different NPRACH resources are associated with different coverage enhancement levels.

44. The method of claim 41, further comprising:

receiving a random access preamble from the UE based on the PRACH resource associated with the early data transmission.

45. The method of claim 44, further comprising:

transmitting a random access response to the UE, the random access response comprising an uplink grant for the early data transmission without establishing the RRC connection with the UE, wherein the data communication is received from the UE based on the uplink grant.

46. The method of claim 33, wherein the data comprises a non-access stratum (NAS) Protocol Data Unit (PDU) received at the control plane.

47. The method of claim 33, further comprising:

forwarding the data to a core network without establishing the RRC connection with the UE.

48. The method of claim 33, further comprising:

transmitting downlink data communications to the UE on the control plane without establishing the RRC connection with the UE.

49. The method of claim 48, wherein the downlink data communication is transmitted in an RRC message indicating early data transmission completion.

50. An apparatus for wireless communications by a base station without a Radio Resource Control (RRC) connection to a User Equipment (UE), comprising:

means for indicating a resource in system information; and

means for receiving data communications from the UE over a control plane without establishing the RRC connection with the UE,

wherein the data communication comprises data and a cause indication.

51. The apparatus of claim 50, further comprising:

means for forwarding the data to a core network without establishing the RRC connection with the UE.

52. An apparatus for wireless communications by a base station without a Radio Resource Control (RRC) connection to a User Equipment (UE), comprising:

a memory; and

at least one processor coupled to the memory and configured to:

indicating a resource in the system information; and

receiving data communication on a control plane from the UE without establishing the RRC connection with the UE,

wherein the data communication comprises data and a cause indication.

53. The apparatus of claim 52, wherein the resources indicated in the system information comprise Physical Random Access Channel (PRACH) resources associated with early data transmission, wherein the at least one processor is further configured to:

receiving a random access preamble from the UE based on the PRACH resource associated with the early data transmission.

54. The apparatus of claim 53, wherein the at least one processor is further configured to:

transmitting a random access response to the UE, the random access response comprising an uplink grant for the early data transmission without establishing the RRC connection with the UE, wherein the data communication is received from the UE based on the uplink grant.

55. The apparatus of claim 52, wherein the at least one processor is further configured to:

forwarding the data to a core network without establishing the RRC connection with the UE.

56. The apparatus of claim 52, wherein the at least one processor is further configured to:

transmitting downlink data communications to the UE on the control plane without establishing the RRC connection with the UE.

57. A computer-readable medium storing computer executable code for wireless communications by a base station without a Radio Resource Control (RRC) connection to a User Equipment (UE), comprising code to:

indicating a resource in the system information; and

receiving data communication on a control plane from the UE without establishing the RRC connection with the UE,

wherein the data communication comprises data and a cause indication.

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