Apparatus for communication, user equipment (UE), and method implemented by UE

Abstract

This document generally describes a method for low-latency PRACH design in unlicensed spectrum. An exemplary apparatus of a user equipment (UE) includes: a memory; and a processing circuit, the processing circuit being configured to: perform a listen-before-talk (LBT) procedure on one or more channels of the unlicensed spectrum. The processing circuit is further configured to: encode a first message for a first transmission associated with a low-latency random access (RA) procedure on the unlicensed spectrum in response to a clear channel assessment (CCA). The first message includes a physical random access channel (PRACH) preamble and a message portion. The message portion includes at least one of a cell radio network temporary identifier (C‑RNTI), a buffer status report (BSR) information, UE capabilities, and / or an identification of the UE. The processing circuit is further configured to: encode UL data for transmission in response to receiving an uplink (UL) grant based on the first step of the low-latency RA procedure.

Description

[0001] This application is a divisional application of the patent application with application number 201680081168.7 filed on September 29, 2016, and invention name “Device for communication, user equipment (UE) and method implemented by UE”.

[0002] Priority Declaration

[0003] This patent application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 62 / 307,202, filed on March 11, 2016, and U.S. Provisional Patent Application Serial No. 62 / 302,398, filed on March 2, 2016, which are hereby incorporated by reference in their entireties. Technical Field

[0004] Embodiments relate to cellular networks. Some embodiments relate to carrier aggregation in 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) networks and LTE-Advanced (LTE-A) networks, as well as fourth generation (4G) networks and fifth generation (5G) networks. Background Art

[0005] Enhancements to LTE in 3GPP Release 13 are used to enable operation in unlicensed spectrum through Licensed Assisted Access (LAA), which extends system bandwidth by leveraging a flexible carrier aggregation (CA) framework. Potential LTE operation in unlicensed spectrum can include LTE operation in unlicensed spectrum via dual connectivity (DC), or a standalone LTE system in unlicensed spectrum (e.g., MuLTEfire). BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A wireless telecommunications network 100 is shown for performing a low-latency RA procedure according to some embodiments of the present disclosure.

[0007] Figure 2 A block diagram illustrating components of a user equipment (UE) device 1000 according to an embodiment of the present disclosure is shown.

[0008] Figure 3 A signal diagram for a low-latency two-step RA procedure according to some embodiments of the present disclosure is shown.

[0009] Figure 4A A signal diagram of a low-latency, single-step RA procedure for failure is shown according to some embodiments of the present disclosure.

[0010] Figure 4B A signal diagram is shown for a successful low-latency single-step RA procedure according to some embodiments of the present disclosure.

[0011] Figure 5A flowchart of a method for performing a low-latency RA procedure according to some embodiments of the present disclosure is shown.

[0012] Figure 6 A flowchart of a method for performing a low-latency RA procedure according to some embodiments of the present disclosure is shown.

[0013] Figure 7 A flowchart of a method for performing a low-latency RA procedure according to some embodiments of the present disclosure is shown.

[0014] Figure 8 A block diagram is shown of a machine in the example form of a computer system according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0015] The following description and accompanying drawings sufficiently illustrate the specific embodiments to enable those skilled in the art to practice them. Other embodiments may have structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in other embodiments, or may be substituted for portions and features of other embodiments. The embodiments set forth in the claims encompass all available equivalents of those claims.

[0016] Embodiments provide systems and methods for low-latency physical random access channel (PRACH) signaling in unlicensed spectrum via licensed assisted access (LAA) or MulteFire. PRACH can be used for scheduling requests (SR), uplink (UL) synchronization, and power control for initial UL transmissions. Typically, SR may include a contention-based four-step random access procedure, which includes: the UE provides a PRACH preamble signal; the eNodeB responds with a random access request (RAR) signal; the UE provides a message 3 signal with a cell radio network temporary identifier (C-RNTI) or a temporary C-RNTI; and the eNodeB responds with a contention resolution message (e.g., message 4). When operating in unlicensed spectrum, the RA procedure of a radio transmitter may be complicated by a listen-before-talk (LBT) protocol, which is a process in which the radio transmitter first senses the medium and only transmits when the medium is sensed to be idle, also known as clear channel assessment (CCA). CCA utilizes at least energy detection (ED) to determine the presence of a signal on the channel. With LBT employed, both the UE and the eNodeB may perform the LBT procedure before sending their corresponding messages associated with the RACH, which may add significant delay to the random access procedure and may limit UL transmissions.

[0017] Figure 1A wireless telecommunications network 100 is shown for performing a low-latency random access (RA) procedure according to some embodiments of the present disclosure. In some embodiments, the wireless telecommunications network 100 may implement a 3rd Generation Partnership Project (3GPP) fifth generation (5G) wireless network or a 3rd Generation Partnership Project (3GPP) long term evolution advanced (LTE-A) wireless network.

[0018] The illustrative telecommunications network includes an evolved NodeB (eNodeB) 120, which can operate in a corresponding coverage area or cell 122, and a UE 104, which is located within the coverage area of ​​the cell 122. The telecommunications network 100 may include more eNodeBs and / or UEs. The coverage area 122 of the eNodeB 120 may be further divided into three sectors. In some examples, each sector of the eNodeB 120 may also be considered a cell.

[0019] UE 170 may provide transmissions to and receive transmissions from eNodeB 120 in licensed spectrum, unlicensed spectrum, or a combination thereof. Operations in both the licensed spectrum and the unlicensed spectrum may include dual connectivity (DC). Operations in only the unlicensed spectrum may use MuLTEfire. In some examples, operations in the unlicensed spectrum may be via LAA, which may extend the available bandwidth by utilizing a flexible carrier aggregation (CA) framework. To ensure coexistence with incumbent systems and other LAA / MuLTEfire systems, transmissions in the unlicensed spectrum may include performing an LBT procedure and reserving transmissions until CCA is completed and the channel is sensed to be idle.

[0020] In operation, the wireless telecommunications network 100 may include the ability for the eNodeB 120 and the UE 104 to communicate over unlicensed spectrum. To provide UL data to the eNodeB 120, the UE 104 may initiate a SR including a PRACH signal transmission. In addition to the SR, the PRACH signal may be used for uplink (UL) synchronization and power control for initial UL transmissions. Due to the implementation of LBT, the RA process may experience significant delays and may limit UL transmissions.

[0021] In one embodiment supporting a low-latency RA procedure in unlicensed spectrum, the UE 104 and the eNodeB 120 may support a low-latency two-step RA procedure (e.g., in addition to the LBT procedure). In the first step of the low-latency two-step RA procedure, in response to a CCA indicating that the channel is idle (e.g., according to the LBT procedure), the UE 104 may provide a first transmission on the allocated PRACH resources. In one example, the first transmission may include a PRACH preamble and a message portion including a (e.g., temporary or allocated) C-RNTI, buffer status report (BSR) information, capabilities of the UE 104, and message 3, which may include an identity of the UE 104. In some examples, the message portion may also include a common control channel (CCCH) subheader. The message portion may include a medium access control (MAC) portion including possible C-RNTI, BRS information, and layer 1 (L1) / MAC UE capabilities, and a radio resource control (RRC) portion including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity may be included in the MAC part.

[0022] In response to receiving the first transmission, the eNodeB 120 may provide a second transmission including the RAR and / or Message 4, the second transmission being scheduled via a physical downlink control channel (PDCCH) or an evolved PDCCH (ePDCCH) using one of the C-RNTI received from the UE 104 in the first transmission, or a common random access RNTI (RA-RNTI) calculated based on the time-frequency resources used by the preamble of the first transmission.

[0023] The C-RNTI or RA-RNTI included in the second transmission may be based on a contention resolution result of the eNodeB 120. Contention resolution may be performed based on one of the PDCCH / ePDCCH, or either the MAC part or the RRC part (e.g., whichever one was provided by the UE 104 in the first transmission). In the case of being based on the PDCCH / ePDCCH, contention resolution may be considered successful if the PDCCH / ePDCCH includes the UE's assigned C-RNTI. In the case of being based on the MAC part, contention resolution may be considered successful if the MAC part includes the UE 104's assigned C-RNTI, or the UE 104 identity provided in the first transmission. In the case of being based on the RRC part, contention resolution may be considered successful if the RRC message of the RRC part provided in the first transmission includes the UE 104 identity provided in the first transmission.

[0024] The UL grant allocation may be included in the message portion of the RAR, a PDCCH / ePDCCH with the assigned C-RNTI of the UE 104, or a PDCCH / ePDCCH with the assigned RA-RNTI. If included in the PDCCH / ePDCCH with the assigned C-RNTI of the UE 104, the UE 104 may decode the downlink (DL) control information (DCI) for scheduling the RAR / Message 4 and the UL grant masked with the assigned C-RNTI of the UE 104. If included in the PDCCH / ePDCCH with the RA-RNTI, the UE 104 may decode the DL grant for scheduling the RAR / Message 4 and the UL grant for scheduling the PUSCH masked with the assigned RA-RNTI.

[0025] In another embodiment supporting a low-latency RA procedure in unlicensed spectrum, the UE 104 and the eNodeB 120 may support a low-latency single-step RA procedure (e.g., in addition to the LBT procedure). In the first step of the low-latency single-step RA procedure, in response to a CCA indicating that the channel is idle (e.g., according to the LBT procedure), the UE 104 may provide a first transmission on the allocated PRACH resources. The first transmission may include a PRACH preamble and a message portion including a (e.g., temporary or allocated) C-RNTI, BSR information, a CCCH subheader, and / or Message 3, which may include an identity of the UE 104 (e.g., which may be used for contention resolution). The message portion may include a medium access control (MAC) portion including the C-RNTI, BRS information, CCCH subheader, Layer 1 (L1) / MAC UE capabilities, and an RRC portion including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC portion. The first transmission may use a physical uplink control channel (PUCCH) waveform, where the first portion (e.g., n symbols) may be used for a PRACH preamble and the remaining portion (e.g., the remaining m symbols) may be used for a message portion. The duration of the low-latency PUCCH (sPUCCH) may be up to 4 symbols. The sPUCCH may have an interlace structure with 10 physical resource blocks (PRBs) per interlace in a 20 MHz system. One or more interlaces may be assigned to a UE 104 for UL transmissions.

[0026] If an UL grant is received within a predetermined amount of time (e.g., within k subframes, or before the MAC contention resolution timer for the C-RNTI (indicating successful contention resolution) has expired), the UE 104 may transmit UL data normally. The UL grant may be included in a message scheduled via PDCCH / ePDCCH using the C-RNTI received from the UE 104 for the UL grant. Otherwise, the UE 104 may transmit another first transmission with a new random preamble index at a configured PRACH subframe. The time window of k subframes may be counted based on absolute time (e.g., Key Management Service (KMS) time) or based on valid DL subframes (e.g., subframes with DL transmissions).

[0027] For the first transmission of UE 104 in a two-step RA process or a single-step RA process, the first N symbols can be used to send the PRACH preamble. The PRACH preamble can also be used for channel estimation after detection. The remaining M symbols can be used for data transmission (e.g., C-RNTI, BSR information, CCCH subheader, message 3, etc.). For example, when the first PRACH transmission is performed on the sPUCCH resource, N and M can be equal to 2, which is the last 4 SC-FDMA symbols of the special subframe. If one interlace is allocated for the first transmission, in a 20MHz system, there are 20 PRBs available for data transmission on 2 symbols. Using quadrature phase shift keying (QPSK) modulation, each interlace can carry up to 480 bits. In one example, the required payload size for initial access and BSR is 56 bits, with an additional 24 cyclic redundancy check (CRC) bits. With a code rate of 1 / 3, the number of coded bits can be 240, which is much smaller than 480 bits. If the payload size increases beyond 480 bits, additional interlaces may be assigned to the UE 104, or the coding rate may be reduced to allow for a higher density of transmissions.

[0028] When the PRACH preamble requires four symbols on the PUCCH resource, the physical uplink shared channel (PUSCH) subframe following the PUCCH resource can be used to carry the message portion of the first transmission (e.g., C-RNTI, BSR information, CCCH subheader, and Message 3). One or more interlaces of the PUSCH subframe can be allocated for the first transmission, and multiple UEs can be multiplexed in the frequency domain and / or code domain. To reduce the probability of collision, fewer users can be allocated to transmit via the PUSCH subframe. The PRACH preamble sequence can be used for channel estimation. The same structure as for conventional PUSCH transmission can be used, where the demodulation reference signal (DMRS) symbol can be used for channel estimation. If the message portion of the first transmission (e.g., C-RNTI, BSR information, Message 3, and CCCH subheader) sent simultaneously on the allocated PRACH resource cannot be correctly detected, but the PRACH preamble sequence is correctly detected, the two-step / single-step PRACH can fall back to the traditional RA process.

[0029] In systems where the eNodeB 120 and UE 104 support more than one RA procedure (e.g., a combination of a legacy RA procedure, a two-step RA procedure, and a one-step RA procedure), the eNodeB 120 and / or UE 104 may indicate which methods they support or intend to use. In a UE-specific example, the eNodeB 120 may indicate to the UE 104 which RA procedure to use when the UE 104 is in RRC connected mode.

[0030] In a cell-specific procedure, the eNodeB 120 may indicate (e.g., via RRC signaling) which RA procedures it supports, among the traditional RA procedure, the two-step RA procedure, and / or the single-step RA procedure, and the UE 104 may determine which RA procedure to use. One example of a method by which the UE 104 indicates the selected RA procedure to the eNodeB 120 may include using a PRACH preamble signature associated with the selected RA procedure. For example, the eNodeB 120 may specify a set of specific preamble signatures for each supported RA procedure. The UE 104 may use a preamble signal of the set of preamble signatures associated with the selected RA procedure, and the eNodeB 120 may detect the selected RA procedure by detecting the preamble signature.

[0031] Another example of a method by which UE 104 indicates the selected RA procedure to eNodeB 120 may include using specific resources (e.g., time or frequency subcarriers) associated with the selected RA procedure. For example, eNodeB 120 may specify a set of specific resources for each supported RA procedure. UE 104 may use resources from the set of resources associated with the selected RA procedure, and eNodeB 120 may detect the selected RA procedure by the resources on which Message 1 is sent.

[0032] The eNodeB 120 may provide an indication of the selected RA procedure in a master information block (MIB) to the UE 104. The eNodeB 120 may set the PRACH indication in the MIB to a specific value associated with the selected or supported RA procedure. In one example, the eNodeB 120 may indicate the selected RA procedure by setting one or more reserved bits in the payload of the MIB block, or one or more additional bits in the updated MIB payload, to a specific value associated with the selected RA procedure.

[0033] Another example of a method by which the eNodeB 120 may provide an indication of the selected or supported RA procedure to the UE 104 is to indicate it in a system information block (SIB) or an extended SIB (eSIB). The eNodeB 120 may set the selected RA procedure indication in the SIB / eSIB to a specific value associated with the selected RA procedure, and the UE 104 may detect the selected RA procedure based on the selected RA procedure indication in the SIB / eSIB. In one example, the PRACH configuration index parameter of SIB2 / eSIB2 may be extended to include support for one or both of the two-step RA procedure and the single-step RA procedure. The eNodeB 120 may indicate the selected RA procedure by setting the extended PRACH configuration index parameter in SIB2 / eSIB2 to a specific value associated with the selected RA procedure. In another example, new parameters may be added to the SIB / eSIB (e.g., in the PRACH configuration field of SIB2 / eSIB2) for one or both of the two-step RA procedure and the single-step RA procedure. The eNodeB 120 may indicate the selected RA procedure by setting parameters associated with the selected RA procedure in the PRACH configuration field of SIB2 / eSIB2.

[0034] Another example may include providing an indication of the selected RA procedure in higher layer signaling (e.g., RRC signaling). In one example, when the UE 104 is in RRC connected (RRC_CONNECTED) mode, the RRC signaling may configure the RA procedure type for the UE 104. This indication method may be limited to the case where the UE 104 has completed initial access and may not be applicable to the indication of the selected RA procedure for initial access. For example, when the UE 104 is in RRC connected mode and needs to perform the selected RA procedure for UL synchronization and / or scheduling requests, the selected PRACH indication method may be used. The selected PRACH indication method may also be used in handover situations when contention-based PRACH has been issued. The selected PRACH indication method may also be used for RRC reconnection in a situation where the UE 104 attempts to recover from a radio link failure.

[0035] The embodiments described herein may be implemented in a system using any suitably configured hardware and / or software. Figure 2 FIG2 is a block diagram showing components of a user equipment (UE) device 200 according to an embodiment of the present disclosure. The UE 200 may be Figure 1 In some embodiments, the UE device 200 may include application circuitry 202, baseband circuitry 204, radio frequency (RF) circuitry 206, front-end module (FEM) circuitry 208, and one or more antennas 210 coupled together as shown.

[0036] The application circuitry 202 may include one or more application processors. For example, the application circuitry 202 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The processor(s) may include any combination of general-purpose processors and specialized processors (e.g., graphics processors, application processors, etc.). The processor(s) may be coupled to and / or include a memory / storage device and may be configured to execute instructions stored in the memory / storage device to enable various applications and / or operating systems to run on the system.

[0037] The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. The baseband circuitry 204 may include one or more baseband processors and / or control logic to process baseband signals received from the receive signal path of the RF circuitry 206 and generate baseband signals for the transmit signal path of the RF circuitry 206. The baseband processing circuitry 204 may interface with the application circuitry 202 for baseband signal generation and processing, and control the operation of the RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a second-generation (2G) baseband processor 204a, a third-generation (3G) baseband processor 204b, a fourth-generation (4G) baseband processor 204c, and / or one or more other baseband processors 204d for other current generations, generations in development, or generations to be developed in the future (e.g., fifth-generation (5G), 6G, etc.). Baseband circuitry 204 (e.g., one or more of baseband processors 204a-d) may handle various radio control functions that enable communication with one or more radio networks via RF circuitry 206. Radio control functions may include, but are not limited to, signal modulation / demodulation, encoding / decoding, radio frequency shifting, and the like. In some embodiments, the modulation / demodulation circuitry of baseband circuitry 204 may include fast Fourier transform (FFT), precoding, and / or constellation mapping / demapping functions. In some embodiments, the encoding / decoding circuitry of baseband circuitry 204 may include convolution, tail-biting convolution, turbo, Viterbi, and / or low-density parity check (LDPC) encoder / decoder functions. Embodiments of the modulation / demodulation and encoder / decoder functions are not limited to these examples and may include other suitable functions in other embodiments.

[0038] In some embodiments, the baseband circuitry 204 may include elements of a protocol stack, such as elements of the Evolved Universal Terrestrial Radio Access Network (EUTRAN) protocol, including, for example, physical (PHY) elements, medium access control (MAC) elements, radio link control (RLC) elements, packet data convergence protocol (PDCP) elements, and / or radio resource control (RRC) elements. The central processing unit (CPU) 204e of the baseband circuitry 204 may be configured to execute elements of the protocol stack for signaling at the PHY, MAC, RLC, PDCP, and / or RRC layers. In some embodiments, the baseband circuitry may include one or more audio digital signal processors (DSPs) 204f. The audio DSP(s) 204f may be or include elements for compression / decompression and echo cancellation, and in other embodiments may include other suitable processing elements. In some embodiments, the components of the baseband circuitry may be appropriately combined in a single chip or chipset, or arranged on the same circuit board. In some embodiments, some or all of the components of the baseband circuitry 204 and the application circuitry 202 may be implemented together, for example, on a system-on-chip (SOC).

[0039] In some embodiments, baseband circuitry 204 can provide communications compatible with one or more radio technologies. For example, in some embodiments, baseband circuitry 204 can support communications with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) and / or other wireless metropolitan area networks (WMANs), wireless local area networks (WLANs), and wireless personal area networks (WPANs). Embodiments in which baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multimode baseband circuitry.

[0040] RF circuitry 206 can enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, RF circuitry 206 can include switches, filters, amplifiers, etc. to facilitate communication with the wireless network. RF circuitry 206 can include a receive signal path, which can include circuitry for down-converting RF signals received from FEM circuitry 208 and providing a baseband signal to baseband circuitry 204. RF circuitry 206 can also include a transmit signal path, which can include circuitry for up-converting baseband signals provided by baseband circuitry 204 and providing an RF output signal to FEM circuitry 208 for transmission.

[0041] In some embodiments, RF circuitry 206 may include a receive signal path and a transmit signal path. The receive signal path of RF circuitry 206 may include mixer circuitry 206a, amplifier circuitry 206b, and filter circuitry 206c. The transmit signal path of RF circuitry 206 may include filter circuitry 206c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206d for synthesizing frequencies for use by mixer circuitry 206a in the receive signal path and the transmit signal path. In some embodiments, mixer circuitry 206a in the receive signal path may be configured to downconvert an RF signal received from FEM circuitry 208 based on the synthesized frequency provided by synthesizer circuitry 206d. Amplifier circuitry 206b may be configured to amplify the downconverted signal, and filter circuitry 206c may be a low-pass filter (LPF) or a band-pass filter (BPF) configured to remove unwanted signals from the downconverted signal to generate an output baseband signal. The output baseband signal may be provided to baseband circuitry 204 for further processing. In some embodiments, the output baseband signal may be a zero-frequency baseband signal, but this is not a requirement. In some embodiments, mixer circuitry 206a of the receive signal path may include a passive mixer, but the scope of the embodiments is not limited in this respect.

[0042] In some embodiments, mixer circuit 206a of the transmit signal path can be configured to upconvert an input baseband signal based on a synthesized frequency provided by synthesizer circuit 206d to generate an RF output signal for FEM circuit 208. The baseband signal can be provided by baseband circuit 204 and can be filtered by filter circuit 206c. Filter circuit 206c can include a low-pass filter (LPF), but the scope of the embodiments is not limited in this respect.

[0043] In some embodiments, the mixer circuit 206a of the receive signal path and the mixer circuit 206a of the transmit signal path may include two or more mixers and may be arranged to be used for quadrature down conversion and / or quadrature up conversion, respectively. In some embodiments, the mixer circuit 206a of the receive signal path and the mixer circuit 206a of the transmit signal path may include two or more mixers and may be arranged to be used for image rejection (e.g., Hartley image rejection). In some embodiments, the mixer circuit 206a of the receive signal path and the mixer circuit 206a of the transmit signal path may be arranged to be used for direct down conversion and / or direct up conversion, respectively. In some embodiments, the mixer circuit 206a of the receive signal path and the mixer circuit 206a of the transmit signal path may be configured for superheterodyne operation.

[0044] In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, but the scope of the embodiments is not limited in this respect. In some alternative embodiments, the output baseband signal and the input baseband signal may be digital baseband signals. In these alternative embodiments, RF circuitry 206 may include analog-to-digital converter (ADC) circuitry and digital-to-analog converter (DAC) circuitry, and baseband circuitry 204 may include a digital baseband interface to communicate with RF circuitry 206.

[0045] In some dual-mode embodiments, separate radio IC circuitry may be provided to process signals for each spectrum, although the scope of the embodiments is not limited in this respect.

[0046] In some embodiments, synthesizer circuit 206 d may be a fractional-N synthesizer or a fractional-N / N+1 synthesizer, but the scope of the embodiments is not limited in this respect, as other types of frequency synthesizers may be suitable. For example, synthesizer circuit 206 d may be a delta-sigma synthesizer, a frequency multiplier, or a synthesizer including a phase-locked loop with a frequency divider.

[0047] Synthesizer circuit 206d may be configured to synthesize an output frequency based on the frequency input and the divider control input for use by mixer circuit 206a of RF circuit 206. In some embodiments, synthesizer circuit 206d may be a fractional-N / N+1 synthesizer.

[0048] In some embodiments, the frequency input may be provided by a voltage-controlled oscillator (VCO), but this is not required. The divider control input may be provided by baseband circuitry 204 or application processor 202 based on the desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a lookup table based on the channel indicated by application processor 202.

[0049] The synthesizer circuit 206d of the RF circuit 206 may include a frequency divider, a delay-locked loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the frequency divider may be a dual-modulus frequency divider (DMD), and the phase accumulator may be a digital phase accumulator (DPA). In some embodiments, the DMD may be configured to divide the input signal by N or N+1 (e.g., based on a carry out) to provide a fractional division ratio. In some example embodiments, the DLL may include a set of cascaded tunable delay elements, a phase detector, a charge pump, and a D-type flip-flop. In these embodiments, the delay elements may be configured to decompose the VCO cycle into Nd equal phase groups, where Nd is the number of delay elements in the delay line. In this manner, the DLL provides negative feedback to help ensure that the total delay through the delay line is one VCO cycle.

[0050] In some embodiments, synthesizer circuit 206d can be configured to generate a carrier frequency as an output frequency, while in other embodiments, the output frequency can be a multiple of the carrier frequency (e.g., twice the carrier frequency, four times the carrier frequency) and used in conjunction with a quadrature generator and divider circuit to generate multiple signals with multiple different phases at the carrier frequency. In some embodiments, the output frequency can be the LO frequency (fLO). In some embodiments, RF circuit 206 can include an IQ / polarity converter. In some embodiments, RF circuit 206 can include a MIMO transceiver.

[0051] FEM circuitry 208 may include a receive signal path that may include circuitry configured to operate on RF signals received from one or more antennas 210, amplify the received signals, and provide the amplified versions of the received signals to RF circuitry 206 for further processing. FEM circuitry 208 may also include a transmit signal path that may include circuitry configured to amplify signals provided for transmission by RF circuitry 206 for transmission by one or more of one or more antennas 210.

[0052] In some embodiments, the FEM circuitry 208 may include a TX / RX switch to switch between transmit and receive modes of operation. The FEM circuitry may include a receive signal path and a transmit signal path. The receive signal path of the FEM circuitry may include a low noise amplifier (LNA) to amplify a received RF signal and provide the amplified received RF signal as an output (e.g., to the output of the RF circuitry 206). The transmit signal path of the FEM circuitry 208 may include a power amplifier (PA) to amplify an input RF signal (e.g., provided by the RF circuitry 206) and may include one or more filters to generate an RF signal for subsequent transmission (e.g., by one or more of the one or more antennas 210).

[0053] In some embodiments, the UE device 200 may include additional elements, such as memory / storage, a display, a camera, sensors, and / or input / output (I / O) interfaces.

[0054] In operation, the UE device 200 can communicate over both the licensed spectrum and the unlicensed spectrum (e.g., via the baseband circuitry 204, the RF circuitry 206, and the FEM circuitry 208). In some examples, the UE device 200 can support simultaneous transmission over the licensed spectrum (e.g., PCell) and the unlicensed spectrum (e.g., SCell). To provide UL data to the eNodeB, the UE device 200 can initiate a SR via PRACH signaling (e.g., via the FEM circuitry 208). In addition to SR, the PRACH signal can be used for uplink (UL) synchronization and power control for initial UL transmissions. Because LBT is implemented, the RA process may incur significant delays and may limit UL transmissions. It should be understood that the LBT process and the PRACH transmission can be performed by at least a combination of the baseband circuitry 204, the RF circuitry 206, and the FEM circuitry 208.

[0055] In one embodiment of supporting a low latency RA procedure in an unlicensed spectrum, the UE device 200 may support a low latency two-step RA procedure (e.g., in addition to the LBT procedure). In the first step of the low latency two-step RA procedure, in response to a CCA indicating that the channel is idle (e.g., according to the LBT procedure), the UE device 200 may provide a first transmission on the allocated PRACH resources. In one example, the first transmission may include a PRACH preamble and a message portion including a (e.g., temporary or allocated) C-RNTI, BSR information, capabilities of the UE device 200, and message 3, which may include an identifier of the UE device 200 (e.g., which may be used for contention resolution). In some examples, the message portion may also include a CCCH subheader. The message portion may include a MAC portion including possible C-RNTI, BRS information, and L1 / MAC UE capabilities, and an RRC portion including an RRC message with a UE identifier for contention resolution. Alternatively, the UE identifier for contention resolution may be included in the MAC portion. In a second step, the UE device 200 may receive a second transmission including the RAR and / or message 4, which is scheduled via PDCCH / ePDCCH using one of the C-RNTI received from the UE 104 in the first transmission or a common random access RNTI (RA-RNTI) calculated based on the time-frequency resources used by the preamble of the first transmission.

[0056] The UL grant allocation may be included in the message portion of the RAR, a PDCCH / ePDCCH with the allocated C-RNTI of the UE device 200, or a PDCCH / ePDCCH with the allocated RA-RNTI. If included in the PDCCH / ePDCCH with the allocated C-RNTI of the UE device 200, the UE device 200 may decode the downlink DL DCI for scheduling the RAR / Message 4 and the UL grant masked with the allocated C-RNTI of the UE. If included in the PDCCH / ePDCCH with the RA-RNTI, the UE device 200 may decode the DL grant for scheduling the RAR / Message 4 and the UL grant for scheduling the PUSCH masked with the allocated RA-RNTI.

[0057] In another embodiment of supporting a low-latency RA procedure in an unlicensed spectrum, the UE device 200 may support a low-latency single-step RA procedure (e.g., in addition to the LBT procedure). For example, in response to a CCA indicating that the channel is idle (e.g., according to the LBT procedure), the UE device 200 may provide a first transmission on the allocated PRACH resources. The first transmission may include a PRACH preamble and a message portion including a (e.g., temporary or allocated) C-RNTI, BSR information, a CCCH subheader, and message 3, which may include an identity of the UE device 200 (e.g., which may be used for contention resolution at the eNodeB). The message portion may include a medium access control (MAC) portion including a temporary C-RNTI, BRS information, a CCCH subheader, and layer 1 (L1) / MAC UE capabilities, and an RRC portion including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC portion. The first transmission may use a physical uplink control channel (PUCCH) waveform, where the first n symbols may be used for a PRACH preamble and the remaining m symbols may be used for data (e.g., BSR, Message 3) transmission. The duration of the sPUCCH may be up to 4 symbols. The sPUCCH may have an interleaving structure, where there are 10 physical resource blocks (PRBs) per interlace in a 20 MHz system. One or more interlaces may be assigned to the UE device 200 for UL transmission.

[0058] If an UL grant is received within a predetermined amount of time (e.g., within k subframes, or before the MAC contention resolution timer for the C-RNTI (indicating successful contention resolution) has expired), the UE device 200 may transmit UL data normally. The UL grant may be included in a message scheduled via the PDCCH / ePDCCH using the C-RNTI received from the UE device 200 for the UL grant. Otherwise, the UE device 200 may transmit another first transmission with a new random preamble index at a configured PRACH subframe. The time window of k subframes may be counted based on absolute time (e.g., Key Management Service (KMS) time) or based on valid DL subframes (e.g., subframes with DL transmissions).

[0059] For the first transmission of the UE device 200 in a two-step process or a single-step process, the first N symbols can be used to send the PRACH preamble. The PRACH preamble can also be used for channel estimation after detection. The remaining M symbols can be used for data transmission (e.g., C-RNTI, BSR information, CCCH subheader, message 3, etc.). In one embodiment, when sending PRACH over sPUCCH resources, N and M can be equal to 2, which can occupy the last 4 SC-FDMA symbols of the special subframe. If the payload size increases beyond the available payload of a single interlace, additional interlaces can be assigned to the UE device 200, or the coding rate can be reduced to allow for higher density transmissions.

[0060] When the PRACH preamble requires four symbols on the PUCCH, the physical uplink shared channel (PUSCH) subframe following the PUCCH can be used to carry the message portion of the first transmission (e.g., C-RNTI, BSR information, CCCH subheader, and Message 3). One or more interlaces of the PUSCH subframe can be allocated for the first transmission, and multiple UEs can be multiplexed in the frequency domain and / or code domain. To reduce the probability of collision, fewer users can be allocated to transmit over the PUSCH subframe. The PRACH preamble sequence can be used for channel estimation. The same structure as for conventional PUSCH transmission can be used, where the demodulation reference signal (DMRS) symbols can be used for channel estimation. If the message portion of the first transmission (e.g., C-RNTI, BSR information, Message 3, and CCCH subheader) sent simultaneously on the allocated PRACH resources cannot be correctly detected, but the PRACH preamble sequence is correctly detected, the two-step / single-step PRACH can fall back to the traditional RA process.

[0061] In a system where the UE device 200 supports more than one RA procedure (e.g., a combination of a traditional RA procedure, a two-step RA procedure, and a single-step RA procedure), the eNodeB and / or the UE device 200 may indicate which methods they support or intend to use. In a UE-specific example, the UE device 200 may receive an assignment of an RA procedure from the eNodeB when the UE device 200 is in RRC mode.

[0062] In a cell-specific procedure, the UE device 200 may receive an indication from the eNodeB as to which RA procedures, among the traditional RA procedure, the two-step RA procedure, and / or the single-step RA procedure, the eNodeB supports, and the UE device 200 may determine which RA procedure to use. One example of a method by which the UE device 200 indicates the selected RA procedure to the eNodeB may include using a PRACH preamble signature associated with the selected RA procedure. For example, the eNodeB may specify a set of specific preamble signatures for each supported RA procedure. The UE device 200 may use a preamble signal of a set of preamble signatures associated with the selected RA procedure, and the eNodeB may detect the selected RA procedure by detecting the preamble signature.

[0063] The UE device 200 may receive an indication of the selected RA procedure in a master information block (MIB). The eNodeB may set the PRACH indication in the MIB to a specific value associated with the selected or supported RA procedure. In one example, the eNodeB 120 may indicate the selected RA procedure by setting one or more reserved bits in the payload of the MIB block, or one or more additional bits in the payload of an updated MIB block, to a specific value associated with the selected RA procedure.

[0064] Another example of a method in which the UE device 200 receives an indication of a selected or supported RA procedure is receiving it in a system information block (SIB) or an extended SIB (eSIB). The eNodeB may set the selected RA procedure indication in the SIB / eSIB to a specific value associated with the selected RA procedure, and the UE device 200 may detect the selected RA procedure based on the selected RA procedure indication in the SIB / eSIB. In one example, the PRACH configuration index parameter of SIB2 / eSIB2 may be extended to include support for one or both of a two-step RA procedure and a single-step RA procedure. The eNodeB may indicate the selected RA procedure by setting the extended PRACH configuration index parameter in SIB2 / eSIB2 to a specific value associated with the selected RA procedure. In another example, a new parameter may be added to the SIB / eSIB (e.g., in the PRACH configuration field of SIB2 / eSIB2) for one or both of the two-step RA procedure and the single-step RA procedure. The eNodeB may indicate the selected RA procedure by setting parameters associated with the selected RA procedure in the PRACH configuration field of SIB2 / eSIB2.

[0065] Another example of a method of indicating the selected RA procedure to the eNodeB by the UE device 200 may include the selected RA procedure indication associated with the SIB / eSIB (eg, a PRACH configuration parameter or additional parameter in a PRACH configuration field of an extended SIB2 / eSIB2).

[0066] Another example may include providing an indication of the selected RA procedure in higher layer signaling (e.g., RRC signaling). In one example, when the UE device 200 is in RRC connected mode, the RRC signaling may configure the RA procedure type for the UE device 200. This indication method may be limited to the case where the UE device 200 has completed initial access and may not be applicable to the indication of the selected RA procedure for initial access.

[0067] Figure 3 A signal diagram 300 for a low-latency two-step RA procedure according to some embodiments of the present disclosure is shown. In an example, a low-latency two-step RA procedure may be established between a UE 304 and an eNodeB 320. The UE 304 may use Figure 1 UE104, Figure 2 UE device 200, or a combination thereof. eNodeB 320 can be used Figure 1 This is achieved by the eNodeB 120.

[0068] UE 304 may communicate with the eNodeB using unlicensed spectrum. Initially, UE 304 may perform an LBT procedure. In response to a CCA, UE 304 may provide a first transmission [1] to eNodeB 320. In one example, the first transmission [1] may include a PRACH preamble and a message portion including a (e.g., temporary or assigned) C-RNTI, buffer status report (BSR) information, capabilities of UE 304, and message 3, which may include an identity of UE 304 (e.g., which may be used for contention resolution). In some examples, the message portion may also include a common control channel (CCCH) subheader. The message portion may include a medium access control (MAC) portion including possible C-RNTI, BRS information, and layer 1 (L1) / MAC UE capabilities, and a radio resource control (RRC) portion including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC portion.

[0069] In a second step, in response to the CCA (e.g., according to the LBT procedure), the eNodeB 320 may provide a second transmission [2] including the RAR and / or message 4, which is scheduled via the PDCCH / ePDCCH using the C-RNTI received from the UE 304 in the first transmission, or a common random access RNTI (RA-RNTI) calculated based on the time-frequency resources used by the preamble of the first transmission.

[0070] Contention resolution may be performed based on one of the PDCCH / ePDCCH, or either the MAC part or the RRC part (e.g., whichever was provided by the UE 304 in the first transmission). In the case of PDCCH / ePDCCH based, contention resolution may be considered successful if the PDCCH / ePDCCH includes the UE's assigned C-RNTI. In the case of MAC based, contention resolution may be considered successful if the MAC part includes the UE 304's assigned C-RNTI or the UE 304 identity provided in the first transmission. In the case of RRC based, contention resolution may be considered successful if the RRC message of the RRC part provided in the first transmission includes the UE 304's assigned C-RNTI or the UE 304 identity provided in the first transmission.

[0071] The UL grant allocation may be included in the message portion of the RAR, a PDCCH / ePDCCH with the assigned C-RNTI of the UE 304, or a PDCCH / ePDCCH with the assigned RA-RNTI. If included in the PDCCH / ePDCCH with the assigned C-RNTI of the UE 304, the UE 304 may decode the downlink DL DCI for scheduling the RAR / Message 4 and the UL grant masked with the assigned C-RNTI of the UE 304. If included in the PDCCH / ePDCCH with the RA-RNTI, the UE 304 may decode the DL grant for scheduling the RAR / Message 4 and the UL grant for scheduling the PUSCH masked with the assigned RA-RNTI.

[0072] Figure 4A A signal diagram 400 is shown for a low-latency, single-step RA procedure for a failure, according to some embodiments of the present disclosure. Figure 4B A signal diagram 401 for a successful low-latency single-step RA procedure according to some embodiments of the present disclosure is shown. In an example, a low-latency single-step RA procedure may be established between a UE 404 and an eNodeB 420. The UE 404 may use Figure 1 UE104, Figure 2 UE device 200, or a combination thereof. eNodeB 420 can be implemented with Figure 1 This is achieved by the eNodeB 120.

[0073] UE 404 may communicate with the eNodeB using unlicensed spectrum. Initially, UE 404 may perform an LBT procedure. In response to CCA, UE 404 may provide a first transmission on the allocated PRACH resources [1]. The first transmission may include a PRACH preamble and a message portion including a (e.g., temporary or allocated) C-RNTI, BSR information, CCCH subheader, and message 3, which may include an identity of UE 404 (e.g., which may be used for contention resolution). The message portion may include a MAC portion including a temporary C-RNTI, BRS information, CCCH subheader, and L1 / MAC UE capabilities, and an RRC portion including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC portion. The first transmission may use a PUCCH waveform, where the first n symbols may be used for the PRACH preamble and the remaining m symbols may be used for data (e.g., BSR, message 3) transmission. The duration of the sPUCCH can be up to 4 symbols. The sPUCCH can have an interleaving structure with 10 physical resource blocks (PRBs) per interlace in a 20 MHz system. One or more interlaces can be assigned to a UE 404 for UL transmission.

[0074] Contention resolution may be performed based on the PDCCH / ePDCCH, or one of the MAC part or the RRC part (e.g., whichever was provided by the UE 404 in the first transmission). In the case of being based on the PDCCH / ePDCCH, contention resolution may be considered successful if the PDCCH / ePDCCH includes the UE's assigned C-RNTI. In the case of being based on the MAC part, contention resolution may be considered successful if the MAC part includes the UE 404's assigned C-RNTI, or the UE 404 identity provided in the first transmission. In the case of being based on the RRC part, contention resolution may be considered successful if the RRC message of the RRC part provided in the first transmission includes the UE 404's assigned C-RNTI, or the UE 404 identity provided in the first transmission.

[0075] The UL grant allocation may be included in the message portion of the RAR, a PDCCH / ePDCCH with the assigned C-RNTI of the UE 404, or a PDCCH / ePDCCH with the assigned RA-RNTI. If included in the PDCCH / ePDCCH with the assigned C-RNTI of the UE 404, the UE 404 may decode the downlink DL DCI for scheduling the RAR / Message 4 and the UL grant masked with the assigned C-RNTI of the UE 404. If included in the PDCCH / ePDCCH with the RA-RNTI, the UE 404 may decode the DL grant for scheduling the RAR / Message 4 and the UL grant for scheduling the PUSCH masked with the assigned RA-RNTI.

[0076] If an UL grant is received within a predetermined amount of time (e.g., within k subframes, or before the MAC contention resolution timer for the C-RNTI (indicating successful contention resolution) has expired), the UE 404 may transmit UL data normally. The UL grant may be included in a message scheduled via PDCCH / ePDCCH with the C-RNTI received from the UE 104 for the UL grant. Otherwise, the UE 404 may transmit another first transmission with a new random preamble index at a configured PRACH subframe [4], as shown in signal diagram 400. The time window of k subframes may be counted based on absolute time (e.g., Key Management Service (KMS) time) or based on valid DL subframes (e.g., subframes with DL transmissions).

[0077] Figure 5 A flow chart of a method 500 for performing a low-latency RA process according to some embodiments of the present disclosure is shown. The method 500 may be performed in Figure 1 UE 104, Figure 2 UE device 200, Figure 3 UE 304, Figure 4A and Figure 4B 404, or a combination thereof.

[0078] The method 500 may include, at 510, performing a listen-before-talk (LBT) procedure on one or more channels of an unlicensed spectrum.

[0079] Method 500 may also include, at 520, encoding a first message associated with a low-latency random access (RA) procedure for a first transmission on unlicensed spectrum in response to a clear channel assessment (CCA). The first message may include a PRACH preamble and a message portion. The message portion may include at least one of a C-RNTI, BSR information, UE capabilities, and a UE identifier. In some examples, the message portion includes a MAC portion, which includes a MAC message. The MAC message may include at least one of the C-RNTI, BSR information, and UE capabilities. The MAC message may also include a UE identifier. In some examples, the message portion may also include an RRC portion, which includes an RRC message. The RRC message may include a UE identifier. The UE capabilities may include one of Layer 1 UE capabilities or MAC UE capabilities. The message portion may also include a CCCH subheader. The first transmission may use a shortened physical uplink control channel (sPUCCH) waveform, wherein a first portion includes a PRACH preamble and a remaining portion includes a message portion. In some examples, the first portion includes the first two symbols of message 3, and the remaining portion includes the next two symbols after the first two symbols of message 3.

[0080] In some examples, the service eNodeB (e.g., Figure 1 eNodeB120, Figure 4A and Figure 4B eNodeB 420, and / or Figure 5 The first message is encoded with an indication that the eNodeB 520 supports or has selected a low-latency RA procedure (eg, via MIB, SIB / eSIB, or RRC signaling).

[0081] The method 500 may also include decoding a second message received in a second transmission associated with a low-latency RA procedure scheduled via a physical downlink control channel (PDCCH). The second message may include a physical downlink shared channel (PDSCH) transmission that includes an UL grant and includes at least one of a random access response or message 4. In some examples, the DCI used to schedule the second message is scrambled via one of a C-RNTI or a RA-RNTI.

[0082] The low-latency RA procedure may further include, in response to receiving the UL grant based on the first transmission, scheduling the UL transmission.

[0083] The method may also include, in response to not receiving an UL grant based on the first transmission within a predetermined time length after the first transmission, encoding a second message for the second transmission on the unlicensed spectrum. The second message may include a second PRACH preamble and a message portion. The predetermined time length may be based on one of an absolute time, a count of valid downlink subframes, or a MAC contention resolution timer. The method 500 may also include, at 530, encoding UL data for transmission in response to receiving an uplink (UL) grant based on the first step of the low-latency RA procedure.

[0084] Figure 6 A flow chart of a method 600 for performing a low-latency RA process according to some embodiments of the present disclosure is shown. The method 600 may be performed in Figure 1 UE 104, Figure 2 UE device 200, Figure 3 UE 304, Figure 4A and Figure 4B 404, or a combination thereof.

[0085] The method 600 may include, at 610, receiving an indication that the serving eNodeB supports low-latency RA procedures and legacy RA procedures.

[0086] The method 600 may also include, at 620, encoding a first message for a first transmission associated with a low-latency RA procedure, the first message comprising a PRACH preamble and a message portion. The method 600 may also include providing an indication to the serving eNodeB of selecting the low-latency RA procedure. In some examples, providing the indication may include selecting a preamble from a set of PRACH preambles designated for the low-latency RA procedure. In some examples, providing the indication may include selecting a time and / or frequency resource for transmitting the PRACH preamble. The time and / or frequency resource may be dedicated to the low-latency RA procedure. The method 600 may also include receiving, from the serving eNodeB, the time and / or frequency resource dedicated to transmitting the PRACH preamble.

[0087] In some examples, method 600 may include receiving an indication of selection of a low-latency RA procedure from a serving eNodeB. In some examples, method 600 may include receiving an indication of selection of a low-latency RA procedure from a serving eNodeB. For example, receiving an indication of selection of a low-latency RA procedure from a serving eNodeB may include determining the selection of the low-latency RA procedure based on a PRACH_ConfigIndex parameter in a system information block 2 (SIB2) or an extended SIB2 (eSIB2). In another example, receiving an indication of selection of a low-latency RA procedure from a serving eNodeB may include determining the selection of the low-latency RA procedure based on a PRACH configuration field in the SIB2 or eSIB2. In some examples, receiving an indication of selection of a low-latency RA procedure from a serving eNodeB may include determining the selection of the low-latency RA procedure based on a value of one or more reserved bits in a master information block. In some examples, receiving an indication of selection of a low-latency RA procedure from a serving eNodeB may include receiving the selected RA procedure in radio resource control signaling.

[0088] Figure 7 A flow chart of a method 700 for performing a low-latency RA process according to some embodiments of the present disclosure is shown. The method 700 may be performed in Figure 1 eNodeB 120, Figure 3 eNodeB 320, Figure 4A and Figure 4B The method may be implemented in any one of the eNodeBs 420 or a combination thereof.

[0089] Method 700 may include, at 710, decoding a first message received from a UE in a first transmission associated with a low-latency RA procedure on an unlicensed spectrum. The first message may include a PRACH preamble and a message portion. The message portion may include at least one of a cell radio network temporary identifier (C-RNTI), a buffer status report (BSR) information, capabilities of the UE, or an identification of the UE. The message portion may include a medium access control (MAC) portion, the MAC portion including a MAC message. The MAC message may include at least one of the C-RNTI, the BSR information, or capabilities of the UE, wherein performing contention resolution includes processing circuitry determining whether the MAC portion includes the C-RNTI. In some examples, the message portion may also include a radio resource control (RRC) portion, the RRC portion including an RRC message. The RRC message may include an identification of the UE. In some examples, the message portion may also include a common control channel (CCCH) subheader.

[0090] The method 700 may also include, at 720, performing a listen-before-talk (LBT) procedure on one or more channels of the unlicensed spectrum. The method 700 may also include, at 730, encoding a second message of a second transmission associated with a low-latency RA procedure in response to the clear channel assessment. The second message may include at least one of a RAR or message 4. The second message may be scheduled via a physical downlink control channel (PDCCH), and / or the second message includes an uplink (UL) grant. In some examples, the second message PDSCH may be scheduled via downlink control information (DCI) scrambled by one of a C-RNTI or a random access RNTI (RA-RNTI).

[0091] In some examples, method 700 may further include determining, based on a comparison of the PRACH preamble with a set of PRACH preambles designated for low-latency RA procedures, a UE selection of a low-latency RA procedure. In some examples, determining the selection of the low-latency RA procedure may include determining the selection based on a set of time and / or frequency resources used for the first transmission. In some examples, method 700 may further include indicating the selection of the low-latency RA procedure based on one or more bits in a master information block or a system information block.

[0092] Figure 8 An example of a block diagram of a machine 800 is generally shown on which any one or more of the techniques (e.g., methods) discussed herein can be performed according to some embodiments. In alternative embodiments, the machine 800 can operate as a standalone device or can be connected (e.g., networked) to other machines. In a networked deployment, the machine 800 can operate as a server machine, a client machine, or both in a server-client network environment. In an example, the machine 800 can function as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 800 can be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile phone, a web appliance, a network router, a switch or bridge, or any machine capable of executing instructions (sequentially or otherwise) specifying actions to be taken by the machine. Furthermore, although only a single machine is shown, the term "machine" should also be construed to include any collection of machines that individually or collectively execute a set (or multiple sets) of instructions to perform any one or more of the methods discussed herein, such as cloud computing, software as a service (SaaS), or other computer cluster configurations.

[0093] Examples as described herein may include logic or multiple components, modules, or mechanisms, or may operate on logic or multiple components, modules, or mechanisms. A module is a tangible entity (e.g., hardware) that can perform a specified operation when in operation. A module includes hardware. In an example, the hardware may be specifically configured to perform a specific operation (e.g., hardwired). In an example, the hardware may include a configurable execution unit (e.g., a transistor, a circuit, etc.) and a computer-readable medium including instructions, wherein the instructions configure the execution unit to perform a specific operation when in operation. Configuration may be performed under the guidance of an execution unit or a loading mechanism. Therefore, when the device is in operation, the execution unit is communicatively coupled to the computer-readable medium. In this example, the execution unit may be a member of more than one module. For example, in operation, the execution unit may be configured by a first set of instructions to implement a first module at a point in time, and reconfigured by a second set of instructions to implement a second module.

[0094] The machine (e.g., a computer system) 800 may include a hardware processor 802 (e.g., a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 804, and a static memory 806, some or all of which may communicate with each other via an interconnection (e.g., a bus) 808. The machine 800 may also include a display unit 810, an alphanumeric input device 812 (e.g., a keyboard), and a user interface (UI) navigation device 814 (e.g., a mouse). In an example, the display unit 810, the alphanumeric input device 812, and the UI navigation device 814 may be a touch screen display. The machine 800 may also include a storage device (e.g., a drive unit) 816, a signal generating device 818 (e.g., a speaker), a network interface device 820, and one or more sensors 821, such as a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensors. The machine 800 may include an output controller 828, for example, a serial (e.g., Universal Serial Bus (USB)), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate with or control one or more peripheral devices (e.g., printer, card reader, etc.).

[0095] The storage device 816 may include a non-transitory machine-readable medium 822 having stored thereon one or more sets of data structures or instructions 824 (e.g., software) that embody or are utilized by any one or more of the techniques or functions described herein. The instructions 824 may also reside, completely or at least partially, within the main memory 804, within the static storage 806, or within the hardware processor 802 during execution by the machine 800. In an example, one or any combination of the hardware processor 802, the main memory 804, the static storage 806, or the storage device 816 may constitute a machine-readable medium.

[0096] Although the machine-readable medium 822 is illustrated as a single medium, the term “machine-readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store one or more instructions 824.

[0097] The term "machine-readable medium" may include any medium that can store, encode, or carry instructions executed by the machine 800 and cause the machine 800 to perform any one or more of the techniques of the present disclosure, or that can store, encode, or carry data structures used by or associated with such instructions. Non-limiting examples of machine-readable media may include solid-state memory, and optical and magnetic media. In an example, a bulk machine-readable medium includes a machine-readable medium having a plurality of particles with a constant (e.g., stationary) mass. Therefore, a bulk machine-readable medium is not a transient propagating signal. Specific examples of bulk machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable hard disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

[0098] Instructions 824 may also be sent or received over a communication network 826 using a transmission medium via a network interface device 820 utilizing any of a number of transmission protocols, such as Frame Relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Hypertext Transfer Protocol (HTTP), etc. Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), a mobile telephone network (e.g., a cellular network), a plain old telephone (POTS) network, and a wireless data network (e.g., a wireless network known as a Wi-Fi network). The Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards, known as .16 family of standards), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, and the like. In an example, the network interface device 820 may include one or more physical jacks (e.g., Ethernet, coaxial, or telephone jacks) or one or more antennas to connect to the communication network 826. In an example, the network interface device 820 may include multiple antennas to enable wireless communication using at least one of the following: single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) technology. The term "transmission medium" shall be taken to include any intangible medium capable of storing, encoding, or carrying instructions to be executed by the machine 800, and includes digital or analog communication signals or other intangible media to facilitate communication of such software.

[0099] As used herein, the term "circuitry" may refer to, may be part of, or may include an application specific integrated circuit (ASIC), an electronic circuit, a (shared, dedicated, or group) processor and / or (shared, dedicated, or group) memory that executes one or more software or firmware programs, combinational logic circuitry, and / or other appropriate hardware components that provide the described functionality. In some embodiments, the circuit may be implemented in one or more software or firmware modules, or functionality associated with the circuit may be implemented by one or more software or firmware modules. In some embodiments, the circuit may include logic that is at least partially operable in hardware.

[0100] In some embodiments, the UE device 1000 may include additional elements, such as memory / storage, a display, a camera, sensors, and / or input / output (I / O) interfaces.

[0101] Additional notes and examples:

[0102] Example 1 is a device of a user equipment (UE), the device comprising: a memory; and a processing circuit, the processing circuit being used to: perform a listen-before-talk (LBT) process on one or more channels of an unlicensed spectrum; and in response to a clear channel assessment (CCA), encode a first message for a first transmission associated with a low-latency random access (RA) process on the unlicensed spectrum, wherein the first message includes a PRACH preamble code and at least one of a message part, wherein the message part includes at least one of a cell radio network temporary identifier (C-RNTI), a buffer status report (BSR) information, UE capabilities, and / or an identification of the UE; and in response to receiving an uplink (UL) authorization based on the low-latency RA process, encode UL data for transmission.

[0103] In Example 2, the subject matter of Example 1 optionally includes, wherein the message portion includes a medium access control (MAC) portion, the MAC portion includes at least one MAC message, wherein the MAC message includes at least one of a C-RNTI, BSR information, or UE capabilities.

[0104] In Example 3, the subject matter of Example 2 optionally includes, wherein the MAC message further includes an identifier of the UE.

[0105] In Example 4, the subject matter of any one or more of Examples 2-3 optionally includes, wherein the message part further includes a radio resource control (RRC) part, the RRC part includes an RRC message, wherein the RRC message includes an identifier of the UE.

[0106] In Example 5, the subject matter of any one or more of Examples 2-4 may optionally include, wherein the UE capabilities include one of layer 1 UE capabilities, or MAC UE capabilities.

[0107] In Example 6, the subject matter of any one or more of Examples 1-5 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0108] In Example 7, the subject matter of Example 6 optionally includes, wherein the processing circuit is used to: in response to not receiving an UL grant based on the first transmission within a predetermined time length after the first transmission, encode a second message of the second transmission on the unlicensed spectrum, wherein the second message includes a second PRACH preamble code and a message portion.

[0109] In Example 8, the subject matter of Example 7 may optionally include, wherein the predetermined length of time is based on one of an absolute time, a count of valid downlink subframes, or a MAC contention resolution timer.

[0110] In Example 9, the subject matter of any one or more of Examples 1-8 optionally includes, wherein the first transmission uses a shortened physical uplink control channel (sPUCCH) waveform, wherein the first portion includes a PRACH preamble and the remaining portion includes a message portion.

[0111] In Example 10, the subject matter of Example 9 may optionally include, wherein the first portion includes first two symbols of message 3, and wherein the remainder includes next two symbols after the first two symbols of message 3.

[0112] In Example 11, the subject matter of any one or more of Examples 1-10 optionally includes, wherein the first transmission includes sending a PRACH preamble code via one or more symbols of a first shortened physical uplink control channel (sPUCCH) subframe, and sending a message portion via a second sPUCCH subframe.

[0113] In Example 12, the subject matter of any one or more of Examples 1-11 optionally includes, wherein the processing circuit is used to: decode a second message received in a second transmission associated with a low latency RA process scheduled via a physical downlink control channel (PDCCH), wherein the second message includes a physical downlink shared channel (PDSCH) transmission, the PDSCH transmission including an UL grant and including at least one of a random access response or a contention resolution message.

[0114] In Example 13, the subject matter of Example 12 may optionally include, wherein downlink control information (DCI) used to schedule the second message is scrambled via one of a C-RNTI or a random access RNTI (RA-RNTI).

[0115] In Example 14, the subject matter of any one or more of Examples 1-13 may optionally include, wherein the processing circuit initiating the low-latency RA procedure is based on receiving an indication that a serving evolved Node B (eNodeB) supports the low-latency RA procedure.

[0116] In Example 15, the subject matter of Example 14 may optionally include, wherein the processing circuit is to indicate selection of the low latency RA procedure to the eNodeB based on selecting the PRACH preamble from a set of PRACH preambles specified for the low latency RA procedure.

[0117] In Example 16, the subject matter of any one or more of Examples 14-15 may optionally include, wherein the processing circuit is to: indicate selection of the low-latency RA procedure to the eNodeB based on selecting time and / or frequency resources for PRACH preamble transmission dedicated to the low-latency RA procedure.

[0118] In Example 17, the subject matter of any one or more of Examples 1-16 may optionally include, wherein the processing circuit is to: in response to a size of the first message exceeding a size allocated to a single PRACH interlace, encode the first message for transmission on multiple PRACH interlaces.

[0119] In Example 18, the subject matter of any one or more of Examples 1-17 may optionally include, wherein the processing circuit is to: encode the message portion for transmission on a plurality of PRACH interlaces.

[0120] In Example 19, the subject matter of any one or more of Examples 1-18 may optionally include, wherein the processing circuit is to: reduce the size of the first message in response to the size of the first message exceeding a size allocated to a single PRACH interlace.

[0121] Example 20 is a device of a user equipment (UE), comprising: a memory; and a processing circuit, the processing circuit being used to: receive an indication that a serving evolved Node B (eNodeB) supports a low-latency random access (RA) process and a traditional RA process; and encode a first message of a first transmission associated with the low-latency RA process, the first message comprising a PRACH preamble code and a message portion.

[0122] In Example 21, the subject matter of Example 20 may optionally include, wherein the processing circuit is to provide an indication to the serving eNodeB to select the low latency RA procedure.

[0123] In Example 22, the subject matter of Example 21 may optionally include, wherein providing the indication to the serving eNodeB to select the low-latency RA procedure comprises the processing circuit being configured to select the preamble from a set of PRACH preambles designated for the low-latency RA procedure.

[0124] In Example 23, the subject matter of any one or more of Examples 21-22 optionally includes, wherein providing an indication to the serving eNodeB to select a low-latency RA procedure includes the processing circuit being configured to: select time and / or frequency resources for PRACH preamble transmission, wherein the time and / or frequency resources are dedicated to the low-latency RA procedure.

[0125] In Example 24, the subject matter of Example 23 may optionally include, wherein the processing circuit is to: receive time and / or frequency resources dedicated for PRACH preamble transmission from a serving eNodeB.

[0126] In Example 25, the subject matter of any one or more of Examples 20-24 may optionally include, wherein the processing circuit is to: receive an indication of selection of a low-latency RA procedure from the serving eNodeB.

[0127] In Example 26, the subject matter of Example 25 optionally includes, wherein receiving an indication of selection of a low latency RA procedure from a serving eNodeB includes the processing circuit being operable to: determine selection of the low latency RA procedure based on a PRACH_ConfigIndex parameter in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0128] In Example 27, the subject matter of any one or more of Examples 25-26 optionally includes, wherein receiving an indication of selection of a low latency RA procedure from a serving eNodeB includes the processing circuit being configured to determine selection of the low latency RA procedure based on a PRACH configuration field in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0129] In Example 28, the subject matter of any one or more of Examples 25-27 optionally includes, wherein receiving an indication of selection of a low-latency RA procedure from the serving eNodeB includes the processing circuit being configured to determine selection of the low-latency RA procedure based on a value of one or more reserved bits in a master information block.

[0130] In Example 29, the subject matter of any one or more of Examples 25-28 may optionally include, wherein receiving an indication of selection of the low-latency RA procedure from the serving eNodeB comprises the processing circuit being configured to receive the selection of the low-latency RA procedure via radio resource control signaling.

[0131] Example 30 is an evolved Node B (eNodeB) apparatus, the apparatus comprising: a memory; and a processing circuit, the processing circuit being configured to: decode a first message received in a first transmission associated with a low-latency random access (RA) procedure on an unlicensed spectrum from a user equipment (UE), wherein the first message comprises a physical random access channel (PRACH) preamble and a message portion, wherein the message portion comprises at least one of a cell radio network temporary identifier (C-RNTI), buffer status report (BSR) information, UE capabilities, or an identifier of the UE; perform a listen-before-talk (LBT) procedure on one or more channels of the unlicensed spectrum; and in response to a clear channel assessment, encode a second message in a second transmission associated with the low-latency RA procedure, wherein the second message comprises at least one of a random access response (RAR) or a contention resolution message, wherein the second message is scheduled via a physical downlink control channel (PDCCH) and / or the second message comprises an uplink (UL) authorization.

[0132] In Example 31, the subject matter of Example 30 optionally includes, wherein the message portion includes a medium access control (MAC) portion, the MAC portion includes a MAC message, wherein the MAC message includes at least one of a C-RNTI, BSR information, or capabilities of the UE.

[0133] In Example 32, the subject matter of Example 31 optionally includes, wherein the message portion further includes a radio resource control (RRC) portion, the RRC portion includes an RRC message, wherein the RRC message includes an identity of the UE.

[0134] In Example 33, the subject matter of any one or more of Examples 30-32 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0135] In Example 34, the subject matter of any one or more of Examples 30-33 optionally includes, wherein the second message PDSCH is scheduled via downlink control information (DCI) scrambled by one of a C-RNTI or a random access RNTI (RA-RNTI).

[0136] In Example 35, the subject matter of any one or more of Examples 30-34 may optionally include, wherein the processing circuit is to provide indication signaling for supporting the low latency RA procedure via radio resource control (RRC) signaling.

[0137] In Example 36, the subject matter of Example 35 can optionally include, wherein the processing circuit is to determine the UE's selection of the low-latency PRACH procedure based on a comparison of the PRACH preamble with a set of PRACH preambles specified for the low-latency PRACH procedure.

[0138] In Example 37, the subject matter of Example 36 can optionally include, wherein the processing circuit is to determine the UE's selection of a low-latency PRACH process based on a set of time and / or frequency resources used for the first transmission.

[0139] In Example 38, the subject matter of any one or more of Examples 36-37 optionally includes, wherein the processing circuit is to: allocate corresponding frequency resources and / or code regions to each UE of the plurality of UEs to allow transmissions from the plurality of UEs to be multiplexed.

[0140] In Example 39, the subject matter of any one or more of Examples 35-38 may optionally include, wherein the processing circuit is to: indicate the selection of the low latency RA procedure based on one or more bits in a master information block or a system information block.

[0141] In Example 40, the subject matter of any one or more of Examples 30-39 may optionally include, wherein the processing circuit is to: perform channel estimation based on the first subset of symbols of the PRACH preamble.

[0142] In Example 41, the subject matter of any one or more of Examples 30-40 may optionally include, wherein the processing circuit is to: perform channel estimation based on the first subset of symbols of the PRACH preamble.

[0143] In Example 42, the subject matter of any one or more of Examples 30-41 optionally includes, wherein the processing circuit is to: perform channel estimation based on a PRACH preamble code transmitted via a previously shortened physical uplink control channel (sPUCCH) subframe.

[0144] In Example 43, the subject matter of Example 42 optionally includes, wherein the processing circuit is to: decode a UL subframe for message transmission following a previous sPUCCH subframe lacking a demodulation reference signal.

[0145] In Example 44, the subject matter of any one or more of Examples 30-43 may optionally include, wherein the processing circuit is to: in response to the message portion of the first message being erroneously detected, revert to a conventional RA procedure.

[0146] Example 45 is at least one machine-readable medium comprising instructions for performing a physical random access channel (PRACH) process in an unlicensed spectrum, the instructions, when executed by the machine, causing the machine to perform the following operations: perform a listen-before-talk (LBT) process on one or more channels of the unlicensed spectrum; in response to a clear channel assessment (CCA), encode a first message for a first transmission associated with a low latency random access (RA) process on the unlicensed spectrum, wherein the first message includes at least one of a PRACH preamble and a message portion, wherein the message portion includes at least one of a cell radio network temporary identifier (C-RNTI), a buffer status report (BSR) information, UE capabilities, or an identification of the UE; and in response to receiving an uplink (UL) grant based on the low latency RA process, encode UL data for transmission.

[0147] In Example 46, the subject matter of Example 45 optionally includes, wherein the message portion comprises a medium access control (MAC) portion, the MAC portion comprises a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or capabilities of the UE.

[0148] In Example 47, the subject matter of Example 46 optionally includes, wherein the MAC message further includes an identification of the UE.

[0149] In Example 48, the subject matter of any one or more of Examples 46-47 optionally includes, wherein the message portion further includes a radio resource control (RRC) portion, the RRC portion includes an RRC message, wherein the RRC message includes an identification of the UE.

[0150] In Example 49, the subject matter of any one or more of Examples 46-48 may optionally include, wherein the UE capabilities include one of layer 1 UE capabilities, or MAC UE capabilities.

[0151] In Example 50, the subject matter of any one or more of Examples 45-49 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0152] In Example 51, the subject matter of Example 50 optionally includes instructions that, when executed by the machine, cause the machine to encode a second message for the second transmission on the unlicensed spectrum in response to not receiving an UL grant based on the first transmission within a predetermined length of time after the first transmission, wherein the second message includes a second PRACH preamble and a message portion.

[0153] In Example 52, the subject matter of Example 51 may optionally include, wherein the predetermined length of time is based on one of an absolute time, a count of valid downlink subframes, or a MAC contention resolution timer.

[0154] In Example 53, the subject matter of any one or more of Examples 45-52 optionally includes, wherein the first transmission uses a shortened physical uplink control channel (sPUCCH) waveform, wherein the first portion includes a PRACH preamble and the remaining portion includes a message portion.

[0155] In Example 54, the subject matter of Example 53 may optionally include, wherein the first portion includes first two symbols of message 3, and wherein the remainder includes next two symbols after the first two symbols of message 3.

[0156] In Example 55, the subject matter of any one or more of Examples 45-54 optionally includes instructions that, when executed by a machine, cause the machine to decode a second message received in a second transmission associated with a low latency RA procedure scheduled via a physical downlink control channel (PDCCH), wherein the second message comprises a physical downlink shared channel (PDSCH) transmission, the PDSCH transmission comprising an UL grant and comprising at least one of a random access response or a contention resolution message.

[0157] In Example 56, the subject matter of Example 55 may optionally include, wherein downlink control information (DCI) used to schedule the second message is scrambled via one of a C-RNTI or a random access RNTI (RA-RNTI).

[0158] In Example 57, the subject matter of any one or more of Examples 45-56 may optionally include, wherein the first message is encoded based on receiving an indication that a serving evolved Node B (eNodeB) supports a low latency RA procedure.

[0159] In Example 58, the subject matter of Example 57 may optionally include instructions, when executed by the machine, causing the machine to indicate selection of the low latency RA procedure to the eNodeB based on selecting time and / or frequency resources for PRACH preamble transmission dedicated to the low latency RA procedure.

[0160] Example 59 is at least one machine-readable medium comprising instructions for performing a physical random access channel (PRACH) process in an unlicensed spectrum, which instructions, when executed by a machine, cause the machine to perform the following operations: receive an indication that a serving evolved Node B (eNodeB) supports a low-latency random access (RA) process and a legacy RA process; and encode a first message for a first transmission associated with the low-latency RA process, the first message comprising a PRACH preamble and a message portion.

[0161] In Example 60, the subject matter of Example 59 may optionally include instructions, when executed by the machine, causing the machine to provide an indication to the serving eNodeB to select a low latency RA procedure.

[0162] In Example 61, the subject matter of Example 60 may optionally include, wherein providing the indication to the serving eNodeB to select the low latency RA procedure comprises instructions that, when executed by the machine, cause the machine to select the preamble from a set of PRACH preambles specified for the low latency RA procedure.

[0163] In Example 62, the subject matter of any one or more of Examples 60-61 may optionally include, wherein providing the indication to the serving eNodeB to select the low latency RA procedure comprises instructions that, when executed by the machine, cause the machine to select time and / or frequency resources for PRACH preamble transmission, wherein the time and / or frequency resources are dedicated to the low latency RA procedure.

[0164] In Example 63, the subject matter of Example 62 may optionally include instructions, when executed by the machine, causing the machine to receive time and / or frequency resources dedicated for PRACH preamble transmission from a serving eNodeB.

[0165] In Example 64, the subject matter of any one or more of Examples 59-63 may optionally include instructions, when executed by the machine, causing the machine to receive an indication of selection of a low latency RA procedure from the serving eNodeB.

[0166] In Example 65, the subject matter of Example 64 optionally includes, wherein receiving the indication of selection of the low latency RA procedure from the serving eNodeB comprises instructions that, when executed by the machine, cause the machine to determine the selection of the low latency RA procedure based on a PRACH_ConfigIndex parameter in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0167] In Example 66, the subject matter of any one or more of Examples 64-65 optionally includes, wherein receiving an indication of selection of a low latency RA procedure from a serving eNodeB comprises instructions that, when executed by the machine, cause the machine to determine selection of the low latency RA procedure based on a PRACH configuration field in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0168] In Example 67, the subject matter of any one or more of Examples 64-66 optionally includes, wherein receiving an indication of selection of a low latency RA procedure from the serving eNodeB includes instructions that, when executed by the machine, cause the machine to determine selection of the low latency RA procedure based on a value of one or more reserved bits in a master information block.

[0169] In Example 68, the subject matter of any one or more of Examples 59-67 optionally includes, wherein receiving an indication of selection of a low-latency RA procedure from the serving eNodeB includes instructions that, when executed by the machine, cause the machine to receive the selection of the low-latency RA procedure via radio resource control signaling.

[0170] Example 69 is at least one machine-readable medium comprising instructions for performing a physical random access channel (PRACH) procedure in an unlicensed spectrum, the instructions, when executed by the machine, causing the machine to perform the following operations: decoding a first message received in a first transmission associated with a low-latency random access (RA) procedure on the unlicensed spectrum from a user equipment (UE), wherein the first message includes a PRACH preamble and a message portion, wherein the message portion includes at least one of a cell radio network temporary identifier (C-RNTI), a buffer status report (BSR) information, UE capabilities, or an identification of the UE; performing a listen-before-talk (LBT) procedure on one or more channels of the unlicensed spectrum; and in response to a clear channel assessment, encoding a second message of a second transmission associated with the low-latency RA procedure, wherein the second message includes at least one of a random access response (RAR) or a contention resolution message, wherein the second message is scheduled via a physical downlink control channel (PDCCH) and / or includes an uplink (UL) authorization.

[0171] In Example 70, the subject matter of Example 69 optionally includes, wherein the message portion comprises a medium access control (MAC) portion, the MAC portion comprises a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or capabilities of the UE.

[0172] In Example 71, the subject matter of Example 70 optionally includes, wherein the message portion further includes a radio resource control (RRC) portion, the RRC portion includes an RRC message, wherein the RRC message includes an identity of the UE.

[0173] In Example 72, the subject matter of any one or more of Examples 69-71 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0174] In Example 73, the subject matter of any one or more of Examples 69-72 optionally includes that the second message PDSCH is scheduled via downlink control information (DCI) scrambled by one of a C-RNTI or a random access RNTI (RA-RNTI).

[0175] In Example 74, the subject matter of any one or more of Examples 69-73 may optionally include instructions that, when executed by the machine, cause the machine to provide indication signaling for supporting a low latency RA procedure via radio resource control (RRC) signaling.

[0176] In Example 75, the subject matter of Example 74 may optionally include instructions that, when executed by the machine, cause the machine to determine selection of a low-latency PRACH process by the UE based on a comparison of the PRACH preamble with a set of PRACH preambles specified for the low-latency PRACH process.

[0177] In Example 76, the subject matter of Example 75 may optionally include instructions, when executed by the machine, causing the machine to determine the UE's selection of a low-latency PRACH process based on a set of time and / or frequency resources used for the first transmission.

[0178] In Example 77, the subject matter of any one or more of Examples 74-76 may optionally include instructions, when executed by a machine, causing the machine to indicate selection of a low latency RA procedure based on one or more bits in a master information block or a system information block.

[0179] Example 78 is a device comprising: a device for performing a listen-before-talk (LBT) procedure on one or more channels of an unlicensed spectrum; a device for encoding a first message for a first transmission associated with a low latency random access (RA) procedure on the unlicensed spectrum in response to a clear channel assessment (CCA), wherein the first message comprises a PRACH preamble and at least one of a message portion, wherein the message portion comprises at least one of a cell radio network temporary identifier (C-RNTI), a buffer status report (BSR) information, UE capabilities, and / or an identification of the UE; and a device for encoding UL data for transmission in response to receiving an uplink (UL) authorization based on the low latency RA procedure.

[0180] In Example 79, the subject matter of Example 78 optionally includes, wherein the message portion includes a medium access control (MAC) portion, the MAC portion includes a MAC message, wherein the MAC message includes at least one of a C-RNTI, BSR information, or capabilities of the UE.

[0181] In Example 80, the subject matter of Example 79 optionally includes, wherein the MAC message further includes an identification of the UE.

[0182] In Example 81, the subject matter of any one or more of Examples 79-80 optionally includes, wherein the message portion further includes a radio resource control (RRC) portion, the RRC portion includes an RRC message, wherein the RRC message includes an identification of the UE.

[0183] In Example 82, the subject matter of any one or more of Examples 79-81 may optionally include, wherein the UE capabilities include one of layer 1 UE capabilities, or MAC UE capabilities.

[0184] In Example 83, the subject matter of any one or more of Examples 78-82 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0185] In Example 84, the subject matter of Example 83 optionally includes an apparatus for encoding a second message for a second transmission on an unlicensed spectrum in response to not receiving an UL grant based on the first transmission within a predetermined length of time after the first transmission, wherein the second message includes a second PRACH preamble and a message portion.

[0186] In Example 85, the subject matter of Example 84 may optionally include, wherein the predetermined length of time is based on one of an absolute time, a count of valid downlink subframes, or a MAC contention resolution timer.

[0187] In Example 86, the subject matter of any one or more of Examples 78-85 optionally includes, wherein the first transmission uses a shortened physical uplink control channel (sPUCCH) waveform, wherein the first portion includes a PRACH preamble and the remaining portion includes a message portion.

[0188] In Example 87, the subject matter of Example 86 optionally includes, wherein the first portion includes first two symbols of message 3, and wherein the remainder includes next two symbols after the first two symbols of message 3.

[0189] In Example 88, the subject matter of any one or more of Examples 78-87 optionally includes an apparatus for decoding a second message received in a second transmission associated with a low latency RA process scheduled via a physical downlink control channel (PDCCH), wherein the second message includes a physical downlink shared channel (PDSCH) transmission, the PDSCH transmission including a UL grant and including at least one of a random access response or a contention resolution message.

[0190] In Example 89, the subject matter of Example 88 may optionally include, wherein downlink control information (DCI) used to schedule the second message is scrambled via one of a C-RNTI or a random access RNTI (RA-RNTI).

[0191] In Example 90, the subject matter of any one or more of Examples 78-89 may optionally include, wherein the first message is encoded based on receiving an indication that a serving evolved Node B (eNodeB) supports a low latency RA procedure.

[0192] In Example 91, the subject matter of Example 90 may optionally include means for indicating selection of the low delay RA procedure to the eNodeB based on selecting time and / or frequency resources for PRACH preamble transmission dedicated to the low delay RA procedure.

[0193] Example 92 is a device comprising: a device for receiving an indication that a serving evolved Node B (eNodeB) supports a low-latency random access (RA) process and a traditional RA process; and a device for encoding a first message sent first associated with the low-latency RA process, the first message comprising a PRACH preamble and a message portion.

[0194] In Example 93, the subject matter of Example 92 may optionally include means for providing an indication to the serving eNodeB to select the low latency RA procedure.

[0195] In Example 94, the subject matter of Example 93 optionally includes, wherein the means for providing an indication to the serving eNodeB to select the low-latency RA procedure further comprises means for selecting a preamble from a set of PRACH preambles specified for the low-latency RA procedure.

[0196] In Example 95, the subject matter of any one or more of Examples 93-94 optionally includes, wherein the apparatus for providing an indication to the serving eNodeB of selecting a low-latency RA procedure further includes, apparatus for selecting time and / or frequency resources for PRACH preamble transmission, wherein the time and / or frequency resources are dedicated to the low-latency RA procedure.

[0197] In Example 96, the subject matter of Example 95 may optionally include means for receiving time and / or frequency resources for PRACH preamble transmission from a serving eNodeB.

[0198] In Example 97, the subject matter of any one or more of Examples 92-96 may optionally include means for receiving an indication of selection of a low-latency RA procedure from a serving eNodeB.

[0199] In Example 98, the subject matter of Example 97 optionally includes, wherein the means for receiving an indication of selection of a low latency RA procedure from a serving eNodeB further comprises means for determining selection of a low latency RA procedure based on a PRACH_ConfigIndex parameter in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0200] In Example 99, the subject matter of any one or more of Examples 97-98 optionally includes, wherein the apparatus for receiving an indication of selection of a low latency RA procedure from a serving eNodeB further comprises apparatus for determining selection of a low latency RA procedure based on a PRACH configuration field in a system information block 2 (SIB2) or an extended SIB2 (eSIB2).

[0201] In Example 100, the subject matter of any one or more of Examples 97-99 optionally includes, wherein the apparatus for receiving an indication of selection of a low-latency RA procedure from a serving eNodeB further includes apparatus for determining selection of a low-latency RA procedure based on a value of one or more reserved bits in a master information block.

[0202] In Example 101, the subject matter of any one or more of Examples 92-100 optionally includes, wherein the means for receiving an indication of selection of a low-latency RA procedure from a serving eNodeB further comprises means for receiving selection of a low-latency RA procedure via radio resource control signaling.

[0203] Example 102 is a device comprising: an apparatus for decoding a first message received in a first transmission associated with a low latency random access (RA) procedure on an unlicensed spectrum from a user equipment (UE), wherein the first message comprises a PRACH preamble and a message portion, wherein the message portion comprises at least one of a cell radio network temporary identifier (C-RNTI), buffer status report (BSR) information, UE capabilities, or an identification of the UE; an apparatus for performing a listen-before-talk (LBT) procedure on one or more channels of the unlicensed spectrum; and an apparatus for encoding a second message in a second transmission associated with the low latency RA procedure in response to a clear channel assessment, wherein the second message comprises at least one of a random access response (RAR) or a contention resolution message, and wherein the second message is scheduled via a physical downlink control channel (PDCCH) and / or comprises an uplink (UL) authorization.

[0204] In Example 103, the subject matter of Example 102 optionally includes, wherein the message portion includes a medium access control (MAC) portion, the MAC portion includes a MAC message, wherein the MAC message includes at least one of a C-RNTI, BSR information, or capabilities of the UE.

[0205] In Example 104, the subject matter of Example 103 optionally includes, wherein the message portion further includes a radio resource control (RRC) portion, the RRC portion includes an RRC message, wherein the RRC message includes an identity of the UE.

[0206] In Example 105, the subject matter of any one or more of Examples 102-104 may optionally include, wherein the message portion further includes a common control channel (CCCH) subheader.

[0207] In Example 106, the subject matter of any one or more of Examples 102-105 may optionally include that the second message PDSCH is scheduled via downlink control information (DCI) scrambled by one of a C-RNTI or a random access RNTI (RA-RNTI).

[0208] In Example 107, the subject matter of any one or more of Examples 102-106 may optionally include means for providing indication signaling for supporting a low latency RA procedure via radio resource control (RRC) signaling.

[0209] In Example 108, the subject matter of Example 107 may optionally include means for determining the UE's selection of the low-latency RA procedure based on a comparison of the PRACH preamble with a set of PRACH preambles designated for the low-latency RA procedure.

[0210] In Example 109, the subject matter of Example 108 may optionally include means for determining the UE's selection of a low-latency PRACH procedure based on a set of time and / or frequency resources used for the first transmission.

[0211] In Example 110, the subject matter of any one or more of Examples 107-109 may optionally include means for indicating selection of the low latency RA procedure based on one or more bits in a master information block or a system information block.

[0212] The above detailed description includes reference to the accompanying drawings, which form a part of the detailed description. The accompanying drawings illustrate specific embodiments that can be implemented by way of illustration. These embodiments are also referred to as "examples" in this article. Such examples may include elements other than those shown or described. However, examples including shown or described elements are also contemplated. In addition, for the specific examples (or one or more aspects thereof) shown or described herein or for other examples (or one or more aspects thereof) shown or described herein, examples using any combination or arrangement of those shown or described elements (or one or more aspects thereof) are also contemplated.

[0213] The publications, patents, and patent documents mentioned in this document are incorporated herein by reference in their entirety, as if individually incorporated by reference. If there are inconsistent usages between those documents incorporated by reference and this document, the usage in the incorporated reference(s) supplements that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0214] In this document, as is common in patent documents, the terms "a" or "an" are used to include one or more, independent of any other instance or usage of "at least one" or "one or more". In this document, unless otherwise indicated, the term "or" is used to refer to a non-exclusive or, i.e., "A or B" includes "A but not B", "B but not A", and "A and B". In the appended claims, the terms "include" and "in which" are used as the plain English equivalents of the corresponding terms "comprise" and "in which". In addition, in the appended claims, the terms "include" and "comprising" are open-ended, i.e., systems, devices, articles, or processes that include elements other than those listed after such terms are still considered to fall within the scope of protection of the claim. In addition, in the appended claims, the terms "first", "second", and "third" etc. are used merely as labels and are not intended to imply a numerical ordering of their objects.

[0215] The above description is intended to be illustrative and not restrictive. For example, the examples described above (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be used by a person of ordinary skill in the art after reading the above description. The abstract is intended to enable the reader to quickly determine the nature of the technical disclosure, for example, in order to comply with 37 CFR § 1.72 (b) of the United States. The submission of the abstract should be understood as not being used to interpret or limit the scope or meaning of the claims. In addition, in the above detailed description, various features may be combined together to simplify the disclosure. However, the claims do not set forth every feature disclosed herein, as the embodiments may characterize a subset of the features. In addition, the embodiments may include fewer features than those disclosed in the specific examples. Therefore, the appended claims are incorporated into the detailed description, with each claim existing independently as a separate embodiment. The scope of the embodiments disclosed herein is determined with reference to the appended claims together with the full scope of equivalents to which such claims are entitled.

Claims

1. A method for communication, comprising: By user equipment UE: receiving cell-specific information including an indication of whether the cell supports a 2-step random access (RA) procedure, wherein the cell-specific information includes two groups of RA preambles, wherein a first group of the two groups of RA preambles is used for the 2-step RA procedure and a second group of the two groups of RA preambles is used for the 4-step RA procedure; Confirm use of the 2-step RA process described; sending a first message for a first transmission to the cell using the 2-step RA procedure over unlicensed spectrum, wherein the first message includes an RA preamble from the first group and a message part, wherein the message part includes at least one of a cell radio network temporary identifier (C-RNTI), buffer status report (BSR) information, and an identity of the UE; and After the first transmission, a second transmission received on a Physical Downlink Control Channel (PDCCH) is decoded.

2. The method according to claim 1, further comprising: A listen-before-talk (LBT) process is performed on one or more channels of the unlicensed spectrum.

3. The method according to any one of claims 1 to 2, wherein In response to a clear channel assessment (CCA), transmitting the first message for the first transmission to the cell using the 2-step RA procedure on the unlicensed spectrum is performed.

4. The method according to any one of claims 1 to 2, wherein The message part includes a medium access control (MAC) part, and the MAC part includes at least one MAC message, wherein the MAC message includes at least one of the C-RNTI, the BSR information, or the capability of the UE.

5. The method according to claim 4, wherein The MAC message also includes the identifier of the UE.

6. The method according to claim 4, wherein: The message part further includes a radio resource control (RRC) part, and the RRC part includes an RRC message, wherein the RRC message includes the identity of the UE.

7. The method according to claim 4, wherein: The UE capability includes one of layer 1 UE capability or MAC UE capability.

8. The method according to any one of claims 1-2 and 5-7, wherein The message portion also includes a common control channel (CCCH) subheader.

9. The method according to any one of claims 1-2 and 5-7, further comprising: In response to not receiving an UL grant based on the first transmission within a predetermined time length after the first transmission, sending a second message of a second transmission on the unlicensed spectrum, wherein the second message includes a physical random access channel (PRACH) preamble and the message part.

10. The method according to claim 9, wherein: The predetermined length of time is based on one of an absolute time, a count of valid downlink subframes, or a MAC contention resolution timer.

11. The method according to any one of claims 1-2, 5-7 and 10, wherein The second transmission includes the C-RNTI.

12. The method according to any one of claims 1-2, 5-7 and 10, wherein The second sending schedules a random access response RAR, wherein the RAR includes the C-RNTI and the non-temporary C-RNTIT-CRNTI.

13. A method for communication, comprising: By base station BS: sending cell-specific information including an indication of whether the cell supports a 2-step random access (RA) procedure to a user equipment (UE), wherein the cell-specific information includes two groups of RA preambles, wherein a first group of the two groups of RA preambles is used for the 2-step RA procedure and a second group of the two groups of RA preambles is used for the 4-step RA procedure; receiving, as part of a 2-step RA procedure performed by the UE, a first message in a first transmission from the UE, wherein the first message comprises an RA preamble from the first group and a message part, wherein the message part comprises at least one of a cell radio network temporary identifier (C-RNTI), buffer status report (BSR) information, and an identity of the UE; and The second message for the second transmission is sent on a physical downlink control channel (PDCCH).

14. The method according to claim 13, further comprising: A listen-before-talk (LBT) process is performed on one or more channels of the unlicensed spectrum.

15. The method according to claim 13, wherein: Transmitting the second message for the second transmission on the PDCCH is performed in response to a clear channel assessment (CCA).

16. The method according to claim 13, further comprising: Indication signaling for supporting a low-latency RA procedure is provided through radio resource control RRC signaling.

17. The method according to claim 13, further comprising: A corresponding frequency resource and / or code region is allocated to each of a plurality of UEs to allow transmissions from the plurality of UEs to be multiplexed.

18. An apparatus for communication, comprising: At least one processor is configured to cause a user equipment (UE) to execute the steps of the method according to any one of claims 1 to 12.

19. An apparatus for communication, comprising: At least one processor is configured to cause the base station to perform the steps of the method according to any one of claims 13 to 17.

20. A computer program product comprising computer instructions, which, when executed by one or more processors, perform the steps of the method according to any one of claims 1 to 17.

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