CN115209562A - Apparatus for communication, user Equipment (UE) and method implemented by UE - Google Patents

Abstract

Methods for low latency PRACH design in unlicensed spectrum are generally described herein. An exemplary apparatus of a User Equipment (UE) includes: a memory; and a processing circuit to: a Listen Before Talk (LBT) procedure is performed on one or more channels of an unlicensed spectrum. The processing circuit is further to: a first transmitted first message associated with a low-latency Random Access (RA) procedure is encoded on an 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 part includes at least one of a cell radio network temporary identifier (C-RNTI), buffer Status Report (BSR) information, a capability of the UE, and/or an identity of the UE. The processing circuit is further to: in response to receiving an Uplink (UL) grant based on a first step of a low-latency RA procedure, UL data is encoded for transmission.

Description

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

The present application is a divisional application of patent applications filed on 9/29/2016 under the name of 201680081168.7 and entitled "apparatus for communication, user Equipment (UE), and method implemented by UE".

Priority declaration

This patent application claims priority to U.S. provisional patent application serial No. 62/307,202 filed on day 11/3/2016 and U.S. provisional patent application serial No. 62/302,398 filed on day 2/3/2016, which are hereby incorporated by reference in their entirety.

Technical Field

Embodiments relate to cellular networks. Some embodiments relate to carrier aggregation in third generation partnership project long term evolution (3 GPP LTE) networks and LTE-advanced (LTE-a) networks, as well as fourth generation (4G) networks and fifth generation (5G) networks.

Background

Enhancements to LTE in 3GPP release 13 are used to enable operation in unlicensed spectrum through Licensed Assisted Access (LAA), which extends the system bandwidth by utilizing a flexible Carrier Aggregation (CA) framework. Potential LTE operation in unlicensed spectrum may include LTE operation in unlicensed spectrum via Dual Connectivity (DC), or standalone LTE systems (e.g., muLTEfire) in unlicensed spectrum.

Drawings

Fig. 1 illustrates a wireless telecommunications network 100 for performing a low-latency RA procedure in accordance with some embodiments of the present disclosure.

Fig. 2 shows a block diagram of components of a User Equipment (UE) device 1000 in accordance with an embodiment of the present disclosure.

Fig. 3 illustrates a signal diagram for a low-latency two-step RA procedure, according to some embodiments of the present disclosure.

Fig. 4A illustrates a signal diagram for a failed low latency single step RA procedure, according to some embodiments of the present disclosure.

Fig. 4B illustrates a signal diagram for a successful low latency single step RA procedure, according to some embodiments of the present disclosure.

Fig. 5 illustrates a flow diagram of a method for performing a low-latency RA procedure in accordance with some embodiments of the present disclosure.

Fig. 6 illustrates a flow diagram of a method for performing a low-latency RA procedure in accordance with some embodiments of the present disclosure.

Fig. 7 illustrates a flow diagram of a method for performing a low latency RA procedure in accordance with some embodiments of the present disclosure.

FIG. 8 shows a block diagram of a machine in the example form of a computer system, according to some embodiments of the present disclosure.

Detailed Description

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

Embodiments provide systems and methods for low latency Physical Random Access Channel (PRACH) signaling in unlicensed spectrum via Licensed Assisted Access (LAA) or MulteFire. The PRACH may be used for Scheduling Request (SR), uplink (UL) synchronization, and power control for initial UL transmission. In general, the SR may include a contention-based four-step random access procedure including: 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 procedure in which the radio transmitter first senses the medium and transmits only when it is sensed that the medium is idle, also referred to as Clear Channel Assessment (CCA). CCA utilizes at least Energy Detection (ED) to determine the presence of a signal on a channel. With LBT, both the UE and the eNodeB may perform LBT procedures before transmitting their respective messages associated with the RACH, which may add a significant amount of delay to the random access procedure and may limit UL transmissions.

Fig. 1 illustrates a wireless telecommunications network 100 for performing a low-latency Random Access (RA) procedure in accordance with some embodiments of the present disclosure. In some embodiments, the wireless telecommunications network 100 may implement a third generation partnership project (3 GPP) fifth generation (5G) wireless network or a third generation partnership project (3 GPP) long term evolution advanced (LTE-a) wireless network.

The illustrative telecommunications network includes an evolved node B (eNodeB) 120 and UEs 104, the eNodeB 120 being operable on a respective coverage area or cell 122, and the UEs 104 being located within the coverage area of the cell 122. The telecommunications network 100 may comprise further enodebs and/or UEs. The coverage area 122 of eNodeB 120 may be further divided into three sectors. In some examples, each sector of eNodeB 120 may also be considered a cell.

UE 170 may provide transmissions to eNodeB 120 and receive transmissions from eNodeB 120 in a licensed spectrum, an unlicensed spectrum, or a combination thereof. Operations in licensed and unlicensed spectrum may include Dual Connectivity (DC). Only operations in the unlicensed spectrum may use MuLTEfire. In some examples, operation in 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 and other LAA/MuLTEfire systems, transmissions in the unlicensed spectrum may include performing LBT procedures and reserving transmissions before CCA is completed and channel clear is sensed.

In operation, the wireless telecommunications network 100 may include the capability of the enodebs 120 and UEs 104 to communicate over unlicensed spectrum. To provide UL data to eNodeB 120, UE 104 may initiate an SR that includes PRACH signaling. In addition to SR, PRACH signals may be used for Uplink (UL) synchronization and power control for initial UL transmissions. Due to the implementation of LBT, the RA procedure may incur large delays and may limit UL transmissions.

In one embodiment that supports low latency RA procedures in unlicensed spectrum, the UE 104 and eNodeB 120 may support low latency two-step RA procedures (e.g., in addition to LBT procedures). In a first step of the low-latency two-step RA procedure, the UE 104 may provide a first transmission on the allocated PRACH resources in response to the CCA indicating that the channel is clear (e.g., according to the LBT procedure). 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 message 3 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 part may include a Medium Access Control (MAC) part including a possible C-RNTI, BRS information, and layer 1 (L1)/MAC UE capabilities, and a Radio Resource Control (RRC) part including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity may be included in the MAC part.

In response to receiving the first transmission, eNodeB 120 may provide a second transmission including the RAR and/or message 4 that is scheduled via a Physical Downlink Control Channel (PDCCH) or an evolved PDCCH (ePDCCH) using one of the C-RNTI received from UE 104 in the first transmission, or a common random access RNTI (RA-RNTI) calculated based on time-frequency resources used by the preamble of the first transmission.

The C-RNTI or RA-RNTI included in the second transmission may be based on a contention resolution result of eNodeB 120. Contention resolution may be performed based on one of the PDCCH/ePDCCH, or either the MAC portion or the RRC portion (e.g., any one provided by the UE 104 in the first transmission). In the PDCCH/ePDCCH based case, contention resolution may be considered successful if the PDCCH/ePDCCH includes the allocated C-RNTI of the UE. In the MAC portion based case, contention resolution may be considered successful if the MAC portion includes the allocated C-RNTI of the UE 104, or the UE 104 identity provided in the first transmission. In the RRC portion based case, contention resolution may be considered successful if the RRC portion RRC message provided in the first transmission includes the UE 104 identification provided in the first transmission.

The UL grant assignment may be included in a message part of the RAR, a PDCCH/ePDCCH with an assigned C-RNTI for the UE 104, or a PDCCH/ePDCCH with an assigned RA-RNTI. If included in the PDCCH/ePDCCH with the allocated C-RNTI of the UE 104, the UE 104 can decode Downlink (DL) control information (DCI) for scheduling RAR/message 4 and UL grants masked with the allocated C-RNTI of the UE 104. If included in the PDCCH/ePDCCH with RA-RNTI, the UE 104 can decode the DL grant masked with the allocated RA-RNTI for scheduling RAR/message 4 and the UL grant for scheduling PUSCH.

In another embodiment that supports low latency RA procedures in unlicensed spectrum, the UE 104 and eNodeB 120 may support low latency single step RA procedures (e.g., in addition to LBT procedures). In a first step of the low latency single step RA procedure, the UE 104 may provide a first transmission on the allocated PRACH resource in response to the CCA indicating that the channel is clear (e.g., according to the LBT procedure). The first transmission may include a PRACH preamble and a message portion including a C-RNTI (e.g., temporary or allocated), BSR information, a CCCH subheader, and/or a message 3, which message 3 may include an identity of the UE 104 (e.g., may be used for contention resolution). The message portion may include a Medium Access Control (MAC) portion including a 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 a first portion (e.g., n symbols) may be used for the PRACH preamble and a remaining portion (e.g., the remaining m symbols) may be used for the message portion. The duration of the low-delay PUCCH (sPUCCH) may be up to 4 symbols. The sPUCCH may have an interlace structure with 10 Physical Resource Blocks (PRBs)/interlaces in a 20MHz system. One or more interlaces may be allocated to the UE 104 for UL transmission.

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

For the first transmission by the UE 104 in the two-step RA procedure or the single-step RA procedure, the first N symbols may be used to transmit the PRACH preamble. The PRACH preamble may also be used for channel estimation after detection. The remaining M symbols may be used for data transmission (e.g., C-RNTI, BSR information, CCCH subheader, message 3, etc.). For example, when the first step PRACH transmission is on sPUCCH resources, N and M may 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, 20 PRBs are available for data transmission on 2 symbols in a 20MHz system. With 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. In the case of a code rate of 1/3, the number of coded bits may be 240, which is much smaller than 480 bits. If the payload size increases beyond 480 bits, additional interlaces may be allocated to the UE 104, or the coding rate may be reduced to allow for higher density transmissions.

When the PRACH preamble requires four symbols on the PUCCH resource, a Physical Uplink Shared Channel (PUSCH) subframe following the PUCCH resource may 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 PUSCH subframes may be allocated for the first transmission, and multiple UEs may be multiplexed in the frequency and/or code domain. To reduce the collision probability, fewer users may be allocated to transmit over the PUSCH subframe. The PRACH preamble sequence may be used for channel estimation. The same structure as a conventional PUSCH transmission may be used, where demodulation reference signal (DMRS) symbols may be used for channel estimation. If the first transmitted message portion (e.g., C-RNTI, BSR information, message 3, and CCCH subheader) transmitted simultaneously on the allocated PRACH resources is not correctly detected, but the PRACH preamble sequence is correctly detected, the two-step/one-step PRACH may fall back to the conventional RA procedure.

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

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

Another example of a method of indicating, by the UE 104, the selected RA procedure to the eNodeB 120 may include using a particular resource (e.g., time or frequency subcarriers) associated with the selected RA procedure. For example, eNodeB 120 may specify a particular set of resources for each supported RA procedure. UE 104 may use resources from a set of resources associated with the selected RA procedure, and eNodeB 120 may detect the selected RA procedure over the resources on which message 1 was sent.

eNodeB 120 may provide an indication of the selected RA procedure to UE 104 in a Master Information Block (MIB). eNodeB 120 may set the PRACH indication in the MIB to a particular value associated with the selected or supported RA procedure. In one example, eNodeB 120 can indicate the selected RA procedure by setting one or more reserved bits in a payload of a MIB block, or one or more additional bits in an updated MIB payload, to a particular value associated with the selected RA procedure.

Another example of a method by which eNodeB 120 provides UE 104 with an indication of selected or supported RA procedures is that may be indicated in a System Information Block (SIB) or extended SIB (eSIB). eNodeB 120 can set the selected RA procedure indication in the SIB/eSIB to a particular value associated with the selected RA procedure, and UE 104 can detect the selected RA procedure based on the selected RA procedure indication in the SIB/eSIB. In one example, the PRACH configuration index parameters 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. eNodeB 120 may indicate the selected RA procedure by setting the extended PRACH configuration index parameter in SIB2/eSIB2 to a particular 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/eSIB 2) for one or both of the two-step RA procedure and the single-step RA procedure. eNodeB 120 may indicate the selected RA procedure by setting parameters associated with the selected RA procedure in the PRACH configuration field of SIB2/eSIB 2.

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 an RRC CONNECTED (RRC _ CONNECTED) mode, RRC signaling may configure an RA procedure type for the UE 104. This indication method may be limited to the case where the UE 104 has completed the initial access and may not be applicable to the indication of the selected RA procedure for the initial access. For example, the selected PRACH indication method may be used 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 also be used in handover situations when a contention based PRACH has been issued. The selected PRACH indication method may also be used for RRC reconnection in case the UE 104 attempts to recover from a radio link failure.

The embodiments described herein may be implemented in a system using any suitably configured hardware and/or software. Fig. 2 shows a block diagram of components of a User Equipment (UE) device 200 according to an embodiment of the disclosure. The UE 200 may be implemented in the UE 104 of fig. 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 at least as shown.

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 special-purpose processors (e.g., graphics processors, application processors, etc.). The processor may be coupled with and/or may include memory/storage and may be configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems to run on the system.

The baseband circuitry 204 may include circuitry such as, but not limited to, one or more single-core or multi-core processors. 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 RF circuitry 206 and to generate baseband signals for the transmit signal path of RF circuitry 206. Baseband processing circuitry 204 may interface with application circuitry 202 for the generation and processing of baseband signals and control the operation of RF circuitry 206. For example, in some embodiments, the baseband circuitry 204 may include a second generation (2G) baseband processor 204a, a third (3G) baseband processor 204b, a fourth generation (4G) baseband processor 204c, and/or other baseband processor(s) 204d for other existing generations, generations in development, or generations to be developed in the future (e.g., fifth generation (5G), 6G, etc.). The baseband circuitry 204 (e.g., one or more of the baseband processors 204 a-d) may process various radio control functions that enable communication with one or more radio networks via the RF circuitry 206. The radio control functions may include, but are not limited to: signal modulation/demodulation, encoding/decoding, radio frequency shifting, etc. In some embodiments, the modulation/demodulation circuitry of the 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 (Viterbi), and/or Low Density Parity Check (LDPC) encoder/decoder functionality. Embodiments of modulation/demodulation and encoder/decoder functions are not limited to these examples, and may include other suitable functions in other embodiments.

In some embodiments, the baseband circuitry 204 may include elements of a protocol stack, e.g., elements of an 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. A Central Processing Unit (CPU) 204e of the baseband circuitry 204 may be configured to run elements of a protocol stack for signaling of 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 may include other suitable processing elements in other embodiments. In some embodiments, components of the baseband circuitry may be combined in a single chip or a single chipset, or arranged on the same circuit board, as appropriate. In some embodiments, some or all of the constituent components of the baseband circuitry 204 and the application circuitry 202 may be implemented together, for example, on a system on a chip (SOC).

In some embodiments, the baseband circuitry 204 may provide communications compatible with one or more radio technologies. For example, in some embodiments, baseband circuitry 204 may support communication with an Evolved Universal Terrestrial Radio Access Network (EUTRAN) and/or other Wireless Metropolitan Area Networks (WMANs), wireless Local Area Networks (WLANs), wireless Personal Area Networks (WPANs). Embodiments in which the baseband circuitry 204 is configured to support radio communications of more than one wireless protocol may be referred to as multi-mode baseband circuitry.

The RF circuitry 206 may enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry 206 may include switches, filters, amplifiers, and the like to facilitate communication with the wireless network. RF circuitry 206 may include a receive signal path that may include circuitry to down-convert RF signals received from FEM circuitry 208 and provide baseband signals to baseband circuitry 204. RF circuitry 206 may also include a transmit signal path that may include circuitry to up-convert baseband signals provided by baseband circuitry 204 and provide RF output signals to FEM circuitry 208 for transmission.

In some embodiments, RF circuitry 206 may include a receive signal path and a transmit signal path. The receive signal path of the RF circuitry 206 may include mixer circuitry 206a, amplifier circuitry 206b, and filter circuitry 206c. The transmit signal path of the RF circuitry 206 may include filter circuitry 206c and mixer circuitry 206a. RF circuitry 206 may also include synthesizer circuitry 206d, which synthesizer circuitry 206d is used to synthesize frequencies for use by mixer circuitry 206a of the receive signal path and the transmit signal path. In some embodiments, the mixer circuitry 206a of the receive signal path may be configured to down-convert the RF signal received from the FEM circuitry 208 based on the synthesized frequency provided by the synthesizer circuitry 206 d. The amplifier circuit 206b may be configured to amplify the downconverted signal, and the filter circuit 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 circuit 206a of the receive signal path may comprise a passive mixer, although the scope of the embodiments is not limited in this respect.

In some embodiments, the mixer circuitry 206a of the transmit signal path may be configured to upconvert the input baseband signal based on a synthesis frequency provided by the synthesizer circuitry 206d to generate an RF output signal for the FEM circuitry 208. The baseband signal may be provided by the baseband circuitry 204 and may be filtered by the filter circuitry 206c. The filter circuit 206c may include a Low Pass Filter (LPF), although the scope of the embodiments is not limited in this respect.

In some embodiments, mixer circuitry 206a of the receive signal path and mixer circuitry 206a of the transmit signal path may comprise two or more mixers and may be arranged 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 for image rejection (e.g., hartley (Hartley) image rejection). In some embodiments, the mixer circuitry 206a of the receive signal path and the mixer circuitry 206a of the transmit signal path may be arranged 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.

In some embodiments, the output baseband signal and the input baseband signal may be analog baseband signals, although 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.

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.

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

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

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 the baseband circuitry 204 or the application processor 202 according to a desired output frequency. In some embodiments, the divider control input (e.g., N) may be determined from a look-up table based on the channel indicated by the application processor 202.

Synthesizer circuit 206d of RF circuit 206 may include a frequency divider, a Delay Locked Loop (DLL), a multiplexer, and a phase accumulator. In some embodiments, the divider may be a dual-mode divider (DMD) and the phase accumulator may be a Digital Phase Accumulator (DPA). In some embodiments, the DMD may be configured to divide an input signal by N or N +1 (e.g., carry out based) to provide a fractional division ratio. In some example embodiments, a 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 period 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.

In some embodiments, synthesizer circuit 206d may be configured to generate a carrier frequency as the output frequency, while in other embodiments the output frequency may 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 at the carrier frequency having multiple phases that are different from each other. In some embodiments, the output frequency may be the LO frequency (fLO). In some embodiments, the RF circuitry 206 may include an IQ/polarity converter. In some embodiments, RF circuitry 206 may include a MIMO transceiver.

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

In some embodiments, FEM circuitry 208 may include TX/RX switches to switch between transmit mode and receive mode 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 the received RF signal and provide the amplified received RF signal as an output (e.g., to the output of RF circuitry 206). The transmit signal path of FEM circuitry 208 may include a Power Amplifier (PA) to amplify an input RF signal (e.g., provided by 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 one or more antennas 210).

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.

In operation, the UE device 200 may 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 may support simultaneous transmission over licensed spectrum (e.g., PCell) and unlicensed spectrum (e.g., SCell). To provide UL data to the eNodeB, the UE device 200 may initiate SR via PRACH signaling (e.g., via the FEM circuitry 208). In addition to SR, PRACH signals may be used for Uplink (UL) synchronization and power control for initial UL transmissions. Because LBT is implemented, the RA procedure may incur large delays and may limit UL transmissions. It should be appreciated that the LBT procedure and PRACH transmission may be performed by at least one combination of the baseband circuitry 204, the RF circuitry 206, and the FEM circuitry 208.

In one embodiment supporting a low-latency RA procedure in unlicensed spectrum, the UE device 200 may support a low-latency two-step RA procedure (e.g., in addition to the LBT procedure). In a first step of the low-latency two-step RA procedure, in response to the CCA indicating that the channel is clear (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 a message 3, which message 3 may include an identity 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 part may include a MAC part including possible C-RNTIs, BRS information, and L1/MAC UE capabilities, and an RRC part including RRC messages with UE identities for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC portion. In a second step, the UE device 200 may receive a second transmission comprising a RAR and/or message 4, the second transmission being 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 time-frequency resources used by the preamble of the first transmission.

The UL grant allocation may be included in a message part of the RAR, a PDCCH/ePDCCH with an allocated C-RNTI for the UE device 200, or a PDCCH/ePDCCH with an 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 RAR/message 4 masked with the allocated C-RNTI of the UE, as well as the UL grant. If included in the PDCCH/ePDCCH with the RA-RNTI, the UE device 200 may decode the DL grant for scheduling RAR/message 4 and the UL grant for scheduling PUSCH masked with the allocated RA-RNTI.

In another embodiment supporting a low-latency RA procedure in 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 the CCA indicating that the channel is clear (e.g., according to an LBT procedure), the UE device 200 may provide a first transmission on the allocated PRACH resource. The first transmission may include a PRACH preamble and a message portion including a C-RNTI (e.g., temporary or allocated), BSR information, a CCCH subheader, and a message 3, which message 3 may include an identity of the UE device 200 (e.g., may be used for contention resolution at the eNodeB). The message part may include a Medium Access Control (MAC) part including a temporary C-RNTI, BRS information, CCCH subheader, and layer 1 (L1)/MAC UE capabilities, and an RRC part including an RRC message with a UE identity for contention resolution. Alternatively, the UE identity for contention resolution may be included in the MAC part. The first transmission may use a Physical Uplink Control Channel (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 sPUCCH may be up to 4 symbols. The sPUCCH may have an interlace structure with 10 Physical Resource Blocks (PRBs)/interlaces in a 20MHz system. One or more interlaces may be allocated to the UE device 200 for UL transmission.

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

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

When the PRACH preamble requires four symbols on the PUCCH, a Physical Uplink Shared Channel (PUSCH) subframe following the PUCCH may 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 PUSCH subframes may be allocated for the first transmission, and multiple UEs may be multiplexed in the frequency and/or code domain. To reduce the collision probability, fewer users may be allocated to transmit over the PUSCH subframe. The PRACH preamble sequence may be used for channel estimation. The same structure as a conventional PUSCH transmission may be used, where demodulation reference signal (DMRS) symbols may be used for channel estimation. If the first transmitted message portion (e.g., C-RNTI, BSR information, message 3, and CCCH subheader) transmitted simultaneously on the allocated PRACH resource is not correctly detected, but the PRACH preamble sequence is correctly detected, the two-step/single-step PRACH may fall back to the conventional RA procedure.

In systems where the UE device 200 supports more than one RA procedure (e.g., a combination of a conventional 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 for an RA procedure from an eNodeB while the UE device 200 is in RRC mode.

In cell-specific procedures, the UE device 200 may receive an indication from the eNodeB of which of the legacy RA procedures, two-step RA procedures, and/or single-step RA procedures the eNodeB supports, and the UE device 200 may determine which RA procedure to use. One example of a method of indicating, by the UE device 200, 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 set of preamble signed preamble signals associated with the selected RA procedure, and the eNodeB may detect the selected RA procedure by detecting the preamble signature.

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, eNodeB 120 can indicate the selected RA procedure by setting one or more reserved bits in a payload of the MIB block, or one or more additional bits in an updated MIB block payload, to a particular value associated with the selected RA procedure.

Another example of a method for the UE device 200 to receive an indication of a selected or supported RA procedure is 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 particular 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 parameters 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, new parameters may be added to the SIB/eSIB (e.g., in the PRACH configuration field of SIB2/eSIB 2) 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/eSIB 2.

Another example of a method of indicating, by the UE device 200, the selected RA procedure to the eNodeB may include a selected RA procedure indication associated with the SIB/eSIB (e.g., a PRACH configuration parameter or additional parameters in a PRACH configuration field of an extended SIB2/eSIB 2).

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

Fig. 3 illustrates a signal diagram 300 for a low-latency two-step RA procedure, in accordance with some embodiments of the present disclosure. In an example, a low latency two-step RA procedure can be established between the UE 304 and the eNodeB 320. The UE 304 may be implemented with the UE 104 of fig. 1, the UE device 200 of fig. 2, or a combination thereof. eNodeB 320 may be implemented with eNodeB 120 of fig. 1.

The UE 304 may communicate with the eNodeB using unlicensed spectrum. Initially, the UE 304 may perform an LBT procedure. In response to the CCA, the UE 304 may provide the eNodeB 320 with a first transmission [1]. In one example, the first transmission [1] 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 304, and a message 3, which message 3 may include an identification of the 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 a 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 part.

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] comprising the RAR and/or message 4, the second transmission [2] being scheduled via 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 time-frequency resources used by the preamble of the first transmission.

Contention resolution may be performed based on one of the PDCCH/ePDCCH, or either the MAC portion or the RRC portion (e.g., any one provided by the UE 304 in the first transmission). In the PDCCH/ePDCCH based case, contention resolution may be considered successful if the PDCCH/ePDCCH includes the allocated C-RNTI of the UE. In the case of a MAC portion, contention resolution may be considered successful if the MAC portion includes the allocated C-RNTI of the UE 304 or the UE 304 identity provided in the first transmission. In the RRC portion based case, contention resolution may be considered successful if the RRC message of the RRC portion provided in the first transmission includes the allocated C-RNTI of the UE 304 or the UE 304 identity provided in the first transmission.

The UL grant allocation may be included in a message part of the RAR, a PDCCH/ePDCCH with an allocated C-RNTI for the UE 304, or a PDCCH/ePDCCH with an allocated RA-RNTI. If included in the PDCCH/ePDCCH with the allocated C-RNTI for the UE 304, the UE 304 can decode the downlink DL DCI for scheduling RAR/message 4 masked with the allocated C-RNTI for the UE 304, as well as the UL grant. If included in the PDCCH/ePDCCH with RA-RNTI, the UE 304 can decode the DL grant for scheduling RAR/message 4 and the UL grant for scheduling PUSCH masked with the allocated RA-RNTI.

Fig. 4A illustrates a signal diagram 400 of a low latency single step RA procedure for failure, in accordance with some embodiments of the present disclosure. Fig. 4B illustrates a signal diagram 401 for a successful low latency single step RA procedure in accordance with some embodiments of the present disclosure. In an example, a low latency single step RA procedure can be established between the UE 404 and the eNodeB 420. The UE 404 may be implemented with the UE 104 of fig. 1, the UE device 200 of fig. 2, or a combination thereof. eNodeB 420 may be implemented with eNodeB 120 of fig. 1.

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

Contention resolution may be performed based on PDCCH/ePDCCH, or one of the MAC portion or RRC portion (e.g., any one provided by UE 404 in the first transmission). In the PDCCH/ePDCCH based case, contention resolution may be considered successful if the PDCCH/ePDCCH includes the allocated C-RNTI of the UE. In the case of a MAC portion, contention resolution may be considered successful if the MAC portion includes the allocated C-RNTI of the UE 404, or the UE 404 identity provided in the first transmission. In the RRC portion based case, contention resolution may be considered successful if the RRC portion RRC message provided in the first transmission includes the allocated C-RNTI of the UE 404, or the UE 404 identity provided in the first transmission.

The UL grant assignment may be included in a message part of the RAR, a PDCCH/ePDCCH with an assigned C-RNTI for the UE 404, or a PDCCH/ePDCCH with an assigned RA-RNTI. If included in the PDCCH/ePDCCH with the allocated C-RNTI for the UE 404, the UE 404 can decode the downlink DL DCI for scheduling RAR/message 4 masked with the allocated C-RNTI for the UE 404, as well as the UL grant. If included in the PDCCH/ePDCCH with RA-RNTI, the UE 404 can decode the DL grant for scheduling RAR/message 4 and the UL grant for scheduling PUSCH masked with the allocated RA-RNTI.

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

Fig. 5 illustrates a flow diagram of a method 500 for performing a low-latency RA procedure in accordance with some embodiments of the present disclosure. The method 500 may be implemented in any one of the UE 104 of fig. 1, the UE apparatus 200 of fig. 2, the UE 304 of fig. 3, the UE 404 of fig. 4, or a combination thereof.

Method 500 may include, at 510, performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum.

The method 500 may also include, at 520, encoding a first transmitted first message associated with a low latency Random Access (RA) procedure over an unlicensed spectrum in response to a Clear Channel Assessment (CCA). The first message may include a PRACH preamble and a message portion. The message part may include at least one of a C-RNTI, BSR information, a capability of the UE, and an identity of the UE. In some examples, the message part includes a MAC part, the MAC part including a MAC message. The MAC message may include at least one of C-RNTI, BSR information, and capabilities of the UE. The MAC message may also include an identification of the UE. In some examples, the message portion may also include an RRC portion, the RRC portion including RRC messages. The RRC message may include an identification of the UE. The capability of the UE may include one of a layer 1UE capability, or a MAC UE capability. The message portion may also include a CCCH subheader. The first transmission may use a shortened physical uplink control channel (sPUCCH) waveform, where the first portion includes a PRACH preamble and the 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.

In some examples, the first message may be encoded based on receiving an indication that a serving eNodeB (e.g., eNodeB 120 of fig. 1, eNodeB 420 of fig. 4, and/or eNodeB 520 of fig. 5) supports or has selected a low-latency RA procedure (e.g., through MIB, SIB/eSIB, or RRC signaling).

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 including a UL grant and including at least one of a random access response or message 4. In some examples, the DCI for scheduling the second message is scrambled via one of the C-RNTI or the RA-RNTI.

The low-latency RA procedure may also include scheduling a UL transmission in response to receiving a UL grant based on the first transmission.

The method may also include, in response to not receiving the UL grant based on the first transmission within a predetermined length of time after the first transmission, encoding a second message of a second transmission over the unlicensed spectrum. The second message may include a second PRACH preamble and a message portion. The predetermined length of time 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, in response to receiving an Uplink (UL) grant based on the first step of the low-latency RA procedure, encoding UL data for transmission.

Fig. 6 illustrates a flow diagram of a method 600 for performing a low-latency RA procedure in accordance with some embodiments of the present disclosure. The method 600 may be implemented in any one of the UE 104 of fig. 1, the UE apparatus 200 of fig. 2, the UE 304 of fig. 3, the UE 404 of fig. 4, or a combination thereof.

The method 600 can include, at 610, receiving an indication that a serving eNodeB supports a low latency RA procedure and a legacy RA procedure.

The method 600 may also include, at 620, encoding a first transmitted first message associated with the 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 to select the low-latency RA procedure. In some examples, providing the indication may include selecting a preamble from a set of PRACH preambles specified for the low-latency RA procedure. In some examples, providing the indication may include selecting time and/or frequency resources for PRACH preamble transmission. Time and/or frequency resources may be dedicated to the low-latency RA procedure. The method 600 may also include receiving time and/or frequency resources dedicated to PRACH preamble transmission from a serving eNodeB.

In some examples, the method 600 may include receiving an indication of a selection of a low latency RA procedure from a serving eNodeB. In some examples, the method 600 may include receiving an indication of a selection of a low latency RA procedure from a serving eNodeB. For example, receiving the indication of the selection of the low-latency RA procedure from the 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 (SIB 2) or an extended SIB2 (eSIB 2). In another example, receiving the indication of the selection of the low latency RA procedure from the serving eNodeB may include determining the selection of the low latency RA procedure based on a PRACH configuration field in SIB2 or eSIB 2. In some examples, receiving the indication of the selection of the low latency RA procedure from the 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 the indication of the selection of the low latency RA procedure from the serving eNodeB may include receiving the selected RA procedure in radio resource control signaling.

Fig. 7 illustrates a flow diagram of a method 700 for performing a low latency RA procedure in accordance with some embodiments of the present disclosure. The method 700 may be implemented in any one of the enodebs 120 of fig. 1, 320 of fig. 3, 420 of fig. 4, or a combination thereof.

The method 700 may include, at 710, decoding a first message received in a first transmission associated with a low latency RA procedure over an unlicensed spectrum from a UE. The first message may include a PRACH preamble and a message portion. The message part may include at least one of a cell radio network temporary identifier (C-RNTI), buffer Status Report (BSR) information, capabilities of the UE, or an identity of the UE. The message part may include a Medium Access Control (MAC) part, the MAC part including a MAC message. The MAC message may include at least one of C-RNTI, BSR information, or capabilities of the UE, wherein performing contention resolution comprises the 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.

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 can further include, at 730, encoding a second transmitted second message associated with the low latency RA procedure in response to the clear channel assessment. The second message may comprise at least one of the RAR or message 4. The second message may be scheduled via a Physical Downlink Control Channel (PDCCH), and/or the second message comprises 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).

In some examples, the method 700 may further include determining a selection of a low latency RA procedure by the UE based on a comparison of the PRACH preamble to a set of PRACH preambles specified for the 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 for the first transmission. In some examples, the 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.

Fig. 8 generally illustrates an example of a block diagram of a machine 800 on which any one or more of the techniques (e.g., methods) discussed herein may be executed, according to some embodiments. In alternative embodiments, the machine 800 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 800 may operate in the capacity of a server machine, a client machine, or both, in server-client network environments. In an example, the machine 800 may operate as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 800 may be a Personal Computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

Examples as described herein may include, or may operate on, logic or multiple components, modules, or mechanisms. A module is a tangible entity (e.g., hardware) capable of performing specified operations when operated on. The modules include hardware. In an example, the hardware may be specifically configured to perform certain operations (e.g., hardwired). In an example, the hardware may include configurable execution units (e.g., transistors, circuits, etc.) and a computer-readable medium that includes instructions that, when operated, configure the execution units to perform particular operations. Configuration may be under the direction of an execution unit or loading mechanism. Thus, the execution unit is communicatively coupled to the computer-readable medium when the device is operating. In this example, an execution unit may be a member of more than one module. For example, under operation, an execution unit may be configured by a first set of instructions to implement a first module at one point in time and reconfigured by a second set of instructions to implement a second module.

The machine (e.g., 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 interlink (e.g., 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., drive unit) 816, a signal generation 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, compass, accelerometer, or other sensor. The machine 800 may include an output controller 828, such as 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.).

The storage device 816 may include a non-transitory machine-readable medium 822 having one or more sets of data structures or instructions 824 (e.g., software) stored thereon, the one or more sets of data structures or instructions 824 embodying or being 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 static memory 806, or within the hardware processor 802 during execution thereof by the machine 800. In an example, one or any combination of the hardware processor 802, the main memory 804, the static memory 806, or the storage device 816 may constitute machine-readable media.

While the machine-readable medium 822 is shown to be a single medium, the term "machine-readable medium" can include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) configured to store the one or more instructions 824.

The term "machine-readable medium" may include any medium that is capable of storing, encoding or carrying instructions for execution by the machine 800 and that cause the machine 800 to perform any one or more of the techniques of this disclosure, or that is capable of storing, encoding or carrying 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 high capacity machine-readable medium includes a machine-readable medium having a plurality of particles with a constant (e.g., static) mass. Thus, the mass machine-readable medium is not a transitory propagating signal. Specific examples of the mass machine-readable medium may include: non-volatile memories, 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, e.g., internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions 824 may also be sent or received over a communication network 826 using a transmission medium via the network interface device 820 utilizing any one of a number of transmission protocols (e.g., frame relay, internet Protocol (IP), transmission Control Protocol (TCP), user Datagram Protocol (UDP), hypertext transfer protocol (HTTP), etc.). An example communication network may include: local Area Network (LAN), wide Area Network (WAN), packet data network (e.g., internet), mobile telephone network (e.g., cellular network)Networks), plain Old Telephone (POTS) networks, and wireless data networks (e.g., known as

Of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards, referred to as

IEEE 802.16 family of standards), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, and so forth. 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 wirelessly communicate using at least one of: single Input Multiple Output (SIMO), multiple Input Multiple Output (MIMO), or Multiple Input Single Output (MISO) techniques. The term "transmission medium" shall be taken to include any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine 800, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

As used herein, the term "circuitry" may refer to, may be part of, or may include the following: an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable hardware components that provide the described functionality. In some embodiments, the circuitry may be implemented in, or functions associated with, one or more software or firmware modules. In some embodiments, the circuitry may comprise logic that is at least partially operable in hardware.

In some embodiments, the UE device 1000 may include additional elements, such as memory/storage, a display, a camera, a sensor, and/or an input/output (I/O) interface.

Supplement to explainDescription and examples:

example 1 is an apparatus of a User Equipment (UE), the apparatus comprising: a memory; and a processing circuit to: performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; and in response to a Clear Channel Assessment (CCA), encode a first transmitted first message associated with a low-latency Random Access (RA) procedure over an 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), buffer Status Report (BSR) information, a capability of the UE, and/or an identity of the UE; and in response to receiving an Uplink (UL) grant based on the low-latency RA procedure, encode UL data for transmission.

In example 2, the subject matter of example 1 optionally includes, wherein the message part comprises a Medium Access Control (MAC) part, the MAC part comprising at least one MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or capabilities of the UE.

In example 3, the subject matter of example 2 can optionally include, wherein the MAC message further includes an identification of the UE.

In example 4, the subject matter of any one or more of examples 2-3 optionally includes, wherein the message portion further includes a Radio Resource Control (RRC) portion, the RRC portion including an RRC message, wherein the RRC message includes an identification of the UE.

In example 5, the subject matter of any one or more of examples 2-4 optionally includes wherein the capability of the UE comprises one of a layer 1UE capability, or a MAC UE capability.

In example 6, the subject matter of any one or more of examples 1-5 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

In example 7, the subject matter of example 6 optionally includes, wherein the processing circuitry is to: in response to not receiving the UL grant based on the first transmission within a predetermined length of time after the first transmission, encoding a second message of a second transmission on the unlicensed spectrum, wherein the second message includes a second PRACH preamble and a message portion.

In example 8, the subject matter of example 7 optionally includes 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.

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 comprises a PRACH preamble and the remaining portion comprises a message portion.

In example 10, the subject matter of example 9 can optionally include wherein the first portion includes the first two symbols of message 3, and wherein the remaining portion includes the next two symbols after the first two symbols of message 3.

In example 11, the subject matter of any one or more of examples 1-10 optionally includes, wherein the first transmitting comprises transmitting the PRACH preamble over one or more symbols of a first shortened physical uplink control channel (sPUCCH) subframe and transmitting the message portion over a second sPUCCH subframe.

In example 12, the subject matter of any one or more of examples 1-11 optionally includes, wherein the processing circuitry is to: decoding 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 comprising a UL grant and comprising at least one of a random access response or a contention resolution message.

In example 13, the subject matter of example 12 can optionally include, wherein the Downlink Control Information (DCI) for scheduling the second message is scrambled via one of a C-RNTI, or a random access RNTI (RA-RNTI).

In example 14, the subject matter of any one or more of examples 1-13 optionally includes, wherein the processing circuitry is to initiate the low latency RA procedure is based on receiving an indication that a serving evolved node B (eNodeB) supports the low latency RA procedure.

In example 15, the subject matter of example 14 optionally includes, wherein the processing circuitry is to: the selection of the low latency RA procedure is indicated to the eNodeB based on selecting a PRACH preamble from a set of PRACH preambles specified for the low latency RA procedure.

In example 16, the subject matter of any one or more of examples 14-15 optionally includes, wherein the processing circuitry is to: the selection of the low-latency RA procedure is indicated to the eNodeB based on selecting time and/or frequency resources for PRACH preamble transmission dedicated to the low-latency RA procedure.

In example 17, the subject matter of any one or more of examples 1-16 optionally includes, wherein the processing circuitry is to: in response to a size of the first message exceeding a size allocated to a single PRACH interlace, encoding the first message for transmission on multiple PRACH interlaces.

In example 18, the subject matter of any one or more of examples 1-17 optionally includes, wherein the processing circuitry is to: the message portion is encoded for transmission on multiple PRACH interlaces.

In example 19, the subject matter of any one or more of examples 1-18 optionally includes, wherein the processing circuitry is to: the size of the first message is reduced in response to the size of the first message exceeding a size allocated to a single PRACH interlace.

Example 20 is an apparatus of a User Equipment (UE), the apparatus comprising: a memory; and a processing circuit to: receiving an indication that a serving evolved node B (eNodeB) supports a low-latency Random Access (RA) procedure and a legacy RA procedure; and encoding a first transmitted first message associated with the low latency RA procedure, the first message comprising a PRACH preamble and a message portion.

In example 21, the subject matter of example 20 optionally includes, wherein the processing circuitry is to: an indication to select a low latency RA procedure is provided to a serving eNodeB.

In example 22, the subject matter of example 21 optionally includes, wherein the providing the indication of the selection of the low-latency RA procedure to the serving eNodeB comprises the processing circuitry to: a preamble is selected from a set of PRACH preambles specified for a low latency RA procedure.

In example 23, the subject matter of any one or more of examples 21-22 optionally includes, wherein the providing the indication of selection of the low latency RA procedure to the serving eNodeB comprises the processing circuitry to: selecting time and/or frequency resources for PRACH preamble transmission, wherein the time and/or frequency resources are dedicated to low latency RA procedures.

In example 24, the subject matter of example 23 optionally includes, wherein the processing circuitry is to: time and/or frequency resources dedicated to PRACH preamble transmission are received from a serving eNodeB.

In example 25, the subject matter of any one or more of examples 20-24 optionally includes, wherein the processing circuitry is to: an indication of a selection of a low latency RA procedure is received from a serving eNodeB.

In example 26, the subject matter of example 25, wherein receiving the indication of the selection of the low latency RA procedure from the serving eNodeB comprises the processing circuitry to: the selection of the low-delay RA procedure is determined based on the PRACH _ ConfigIndex parameter in the system information block 2 (SIB 2) or the extended SIB2 (eSIB 2).

In example 27, the subject matter of any one or more of examples 25-26 optionally includes, wherein receiving the indication of the selection of the low latency RA procedure from the serving eNodeB comprises the processing circuitry to: the selection of the low latency RA procedure is determined based on a PRACH configuration field in system information block 2 (SIB 2) or extended SIB2 (eSIB 2).

In example 28, the subject matter of any one or more of examples 25-27 optionally includes, wherein receiving the indication of the selection of the low latency RA procedure from the serving eNodeB comprises the processing circuitry to: the selection of the low latency RA procedure is determined based on a value of one or more reserved bits in the master information block.

In example 29, the subject matter of any one or more of examples 25-28 optionally includes, wherein receiving the indication of the selection of the low latency RA procedure from the serving eNodeB comprises the processing circuitry to: the selection of the low-latency RA procedure is received via radio resource control signaling.

Example 30 is an apparatus of an evolved node B (eNodeB), the apparatus comprising: a memory; and a processing circuit to: decoding a first message received in a first transmission associated with a low-latency Random Access (RA) procedure over 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, a capability of the UE, or an identity of the UE; performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; and in response to the clear channel assessment, encode a second transmitted second message 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) grant.

In example 31, the subject matter of example 30 optionally includes wherein the message part comprises a Medium Access Control (MAC) part comprising a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or capabilities of the UE.

In example 32, the subject matter of example 31 can optionally include, wherein the message portion further includes a Radio Resource Control (RRC) portion, the RRC portion including an RRC message, wherein the RRC message includes an identity of the UE.

In example 33, the subject matter of any one or more of examples 30-32 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

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).

In example 35, the subject matter of any one or more of examples 30-34 optionally includes, wherein the processing circuitry is to: the indication signaling to support the low-latency RA procedure is provided via Radio Resource Control (RRC) signaling.

In example 36, the subject matter of example 35 optionally includes, wherein the processing circuitry is to: the selection of the low latency PRACH procedure by the UE is determined based on a comparison of the PRACH preamble with a set of PRACH preambles specified for the low latency PRACH procedure.

In example 37, the subject matter of example 36 optionally includes, wherein the processing circuitry is to: the selection of the low-latency PRACH procedure by the UE is determined based on a set of time and/or frequency resources for the first transmission.

In example 38, the subject matter of any one or more of examples 36-37 optionally includes, wherein the processing circuitry is to: each of the plurality of UEs is assigned a respective frequency resource and/or code domain to allow multiplexing of transmissions from the plurality of UEs.

In example 39, the subject matter of any one or more of examples 35-38 optionally includes, wherein the processing circuitry is to: the selection of the low latency RA procedure is indicated by being based on one or more bits in a master information block or a system information block.

In example 40, the subject matter of any one or more of examples 30-39 optionally includes, wherein the processing circuitry is to: channel estimation is performed based on a first subset of symbols of a PRACH preamble.

In example 41, the subject matter of any one or more of examples 30-40 optionally includes, wherein the processing circuitry is to: channel estimation is performed based on a first subset of symbols of a PRACH preamble.

In example 42, the subject matter of any one or more of examples 30-41 optionally includes, wherein the processing circuitry is to: channel estimation is performed based on a PRACH preamble transmitted through a previously shortened physical uplink control channel (sPUCCH) subframe.

In example 43, the subject matter of example 42 optionally includes, wherein the processing circuitry is to: decoding a UL subframe for message transmission following a previous sPUCCH subframe lacking a demodulation reference signal.

In example 44, the subject matter of any one or more of examples 30-43 optionally includes, wherein the processing circuitry is to: in response to the message portion of the first message being erroneously detected, a conventional RA procedure is resumed.

Example 45 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 a machine cause the machine to: performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; in response to a Clear Channel Assessment (CCA), encoding a first transmitted first message associated with a low-latency Random Access (RA) procedure over an unlicensed spectrum, wherein the first message comprises at least one of 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, a capability of the UE, or an identity of the UE; and in response to receiving an Uplink (UL) grant based on the low latency RA procedure, encode the UL data for transmission.

In example 46, the subject matter of example 45 optionally includes wherein the message part comprises a Medium Access Control (MAC) part comprising a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or capabilities of the UE.

In example 47, the subject matter of example 46 can optionally include wherein the MAC message further includes an identification of the UE.

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 including an RRC message, wherein the RRC message includes an identification of the UE.

In example 49, the subject matter of any one or more of examples 46-48 optionally includes, wherein the capability of the UE comprises one of a layer 1UE capability, or a MAC UE capability.

In example 50, the subject matter of any one or more of examples 45-49 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

In example 51, the subject matter of example 50 optionally includes the instructions, when executed by the machine, cause the machine to encode a second message of a second transmission over the unlicensed spectrum in response to not receiving a 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.

In example 52, the subject matter of example 51 optionally includes 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.

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 comprises a PRACH preamble and the remaining portion comprises a message portion.

In example 54, the subject matter of example 53 optionally includes wherein the first portion comprises the first two symbols of message 3, and wherein the remaining portion comprises the next two symbols after the first two symbols of message 3.

In example 55, the subject matter of any one or more of examples 45-54 optionally includes the instructions, when executed by the 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 comprising a UL grant and comprising at least one of a random access response or a contention resolution message.

In example 56, the subject matter of example 55 optionally includes wherein the Downlink Control Information (DCI) for scheduling the second message is scrambled via one of a C-RNTI, or a random access RNTI (RA-RNTI).

In example 57, the subject matter of any one or more of examples 45-56 optionally includes, wherein the first message is encoded based on receiving an indication that a serving evolved node B (eNodeB) supports a low latency RA procedure.

In example 58, the subject matter of example 57 optionally includes the instructions, which when executed by the machine, cause the machine to indicate selection of the low latency RA procedure to the eNodeB based on selecting a time and/or frequency resource for PRACH preamble transmission dedicated to the low latency RA procedure.

Example 59 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 a machine, cause the machine to: receiving an indication that a serving evolved node B (eNodeB) supports a low-latency Random Access (RA) procedure and a legacy RA procedure; and encoding a first transmitted first message associated with a low-latency RA procedure, the first message comprising a PRACH preamble and a message portion.

In example 60, the subject matter of example 59 optionally includes the instructions, which when executed by the machine, cause the machine to provide an indication to the serving eNodeB to select the low latency RA procedure.

In example 61, the subject matter of example 60 optionally includes, 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 a preamble from a set of PRACH preambles specified for the low latency RA procedure.

In example 62, the subject matter of any one or more of examples 60-61 optionally includes, wherein the providing the indication to the serving eNodeB to select the low latency RA procedure comprises instructions that, when executed by a 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.

In example 63, the subject matter of example 62 optionally includes the instructions, which when executed by the machine, cause the machine to receive time and/or frequency resources dedicated to PRACH preamble transmission from a serving eNodeB.

In example 64, the subject matter of any one or more of examples 59-63 optionally includes the instructions, which when executed by the machine, cause the machine to receive an indication of selection of the low latency RA procedure from a serving eNodeB.

In example 65, the subject matter of example 64 optionally includes wherein the receiving the indication of the 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 (SIB 2) or an extended SIB2 (eSIB 2).

In example 66, the subject matter of any one or more of examples 64-65 optionally includes, wherein the receiving the indication of the 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 configuration field in a system information block 2 (SIB 2) or an extended SIB2 (eSIB 2).

In example 67, the subject matter of any one or more of examples 64-66 optionally includes, wherein the receiving the indication of the 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 value of one or more reserved bits in the master information block.

In example 68, the subject matter of any one or more of examples 59-67 optionally includes, wherein the receiving the indication of the selection of the low latency RA procedure from the serving eNodeB comprises 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.

Example 69 is at least one machine readable medium comprising instructions to perform a Physical Random Access Channel (PRACH) procedure in an unlicensed spectrum, the instructions when executed by a machine, cause the machine to: decoding a first message received in a first transmission associated with a low-latency Random Access (RA) procedure over 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, a capability of the UE, or an identity of the UE; performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; and in response to the clear channel assessment, encode a second transmitted second message 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 comprises an Uplink (UL) grant.

In example 70, the subject matter of example 69 optionally includes wherein the message part comprises a Medium Access Control (MAC) part comprising a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or a capability of the UE.

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 including an RRC message, wherein the RRC message includes an identity of the UE.

In example 72, the subject matter of any one or more of examples 69-71 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

In example 73, the subject matter of any one or more of examples 69-72 optionally includes the second message PDSCH being scheduled via Downlink Control Information (DCI) scrambled by one of a C-RNTI or a random access RNTI (RA-RNTI).

In example 74, the subject matter of any one or more of examples 69-73 optionally includes the instructions, when executed by the machine, cause the machine to provide the indication signaling to support the low latency RA procedure via Radio Resource Control (RRC) signaling.

In example 75, the subject matter of example 74 optionally includes the instructions, when executed by the machine, cause the machine to determine the selection of the low-latency PRACH procedure by the UE based on a comparison of the PRACH preamble to a set of PRACH preambles specified for the low-latency PRACH procedure.

In example 76, the subject matter of example 75 optionally includes the instructions, which when executed by the machine, cause the machine to determine a selection of the low-latency PRACH procedure by the UE based on a set of time and/or frequency resources for the first transmission.

In example 77, the subject matter of any one or more of examples 74-76 optionally includes instructions that, when executed by a machine, cause the machine to indicate selection of a low latency RA procedure by based on one or more bits in a master information block or a system information block.

Example 78 is an apparatus, comprising: means for performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; means for encoding a first transmitted first message associated with a low-latency Random Access (RA) procedure over an unlicensed spectrum in response to a Clear Channel Assessment (CCA), 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), buffer Status Report (BSR) information, a capability of the UE, and/or an identity of the UE; and means for encoding Uplink (UL) data for transmission in response to receiving an UL grant based on the low-latency RA procedure.

In example 79, the subject matter of example 78 optionally includes wherein the message part comprises a Medium Access Control (MAC) part comprising a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or a capability of the UE.

In example 80, the subject matter of example 79 optionally includes wherein the MAC message further includes an identification of the UE.

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 including an RRC message, wherein the RRC message includes an identification of the UE.

In example 82, the subject matter of any one or more of examples 79-81 optionally includes wherein the capability of the UE comprises one of a layer 1UE capability, or a MAC UE capability.

In example 83, the subject matter of any one or more of examples 78-82 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

In example 84, the subject matter of example 83 optionally includes means for encoding a second message of a second transmission over the unlicensed spectrum in response to not receiving a 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.

In example 85, the subject matter of example 84 optionally includes, 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.

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 comprises a PRACH preamble and the remaining portion comprises a message portion.

In example 87, the subject matter of example 86 can optionally include wherein the first portion includes the first two symbols of message 3, and wherein the remaining portion includes the next two symbols after the first two symbols of message 3.

In example 88, the subject matter of any one or more of examples 78-87 optionally includes means for decoding 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 comprising a UL grant and including at least one of a random access response or a contention resolution message.

In example 89, the subject matter of example 88 optionally includes wherein the Downlink Control Information (DCI) for scheduling the second message is scrambled via one of a C-RNTI, or a random access RNTI (RA-RNTI).

In example 90, the subject matter of any one or more of examples 78-89 can optionally include, wherein the first message is encoded based on receiving an indication that a serving evolved node B (eNodeB) supports low latency RA procedures.

In example 91, the subject matter of example 90 optionally includes means for indicating selection of the low latency RA procedure to an eNodeB based on selection of time and/or frequency resources of PRACH preamble transmission dedicated to the low latency RA procedure.

Example 92 is an apparatus, comprising: means for receiving an indication that a serving evolved node B (eNodeB) supports a low-latency Random Access (RA) procedure and a legacy RA procedure; and means for encoding a first transmitted first message associated with a low latency RA procedure, the first message comprising a PRACH preamble and a message portion.

In example 93, the subject matter of example 92 can optionally include means for providing an indication to the serving eNodeB to select the low-latency RA procedure.

In example 94, the subject matter of example 93 optionally includes wherein the means for providing the 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.

In example 95, the subject matter of any one or more of examples 93-94 optionally includes, wherein the means for providing the indication to the serving eNodeB to select the low latency RA procedure further comprises means 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.

In example 96, the subject matter of example 95 optionally includes means for receiving time and/or frequency resources for PRACH preamble transmission from a serving eNodeB.

In example 97, the subject matter of any one or more of examples 92-96 optionally includes means for receiving, from the serving eNodeB, an indication of selection of the low-latency RA procedure.

In example 98, the subject matter of example 97 can optionally include, wherein the means for receiving an indication of selection of the low latency RA procedure from the serving eNodeB further comprises means for determining selection of the low latency RA procedure based on a PRACH _ ConfigIndex parameter in a system information block 2 (SIB 2) or an extended SIB2 (eSIB 2).

In example 99, the subject matter of any one or more of examples 97-98 may optionally include, wherein the means for receiving an indication of selection of the low latency RA procedure from the serving eNodeB further comprises means for determining selection of the low latency RA procedure based on a PRACH configuration field in a system information block 2 (SIB 2) or an extended SIB2 (eSIB 2).

In example 100, the subject matter of any one or more of examples 97-99 optionally includes, wherein the means for receiving an indication of a selection of the low latency RA procedure from the serving eNodeB further comprises means for 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 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 the low latency RA procedure from the serving eNodeB further comprises means for receiving selection of the low latency RA procedure via radio resource control signaling.

Example 102 is an apparatus, comprising: means for decoding a first message received in a first transmission associated with a low-latency Random Access (RA) procedure over 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, a capability of the UE, or an identity of the UE; means for performing a Listen Before Talk (LBT) procedure on one or more channels of an unlicensed spectrum; and means for encoding a second transmitted second message associated with the low-latency RA procedure in response to the clear channel assessment, 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 comprises an Uplink (UL) grant.

In example 103, the subject matter of example 102 optionally includes wherein the message part comprises a Medium Access Control (MAC) part comprising a MAC message, wherein the MAC message comprises at least one of a C-RNTI, BSR information, or a capability of the UE.

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 including an RRC message, wherein the RRC message includes an identity of the UE.

In example 105, the subject matter of any one or more of examples 102-104 optionally includes, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

In example 106, the subject matter of any one or more of examples 102-105 optionally includes the second message PDSCH being scheduled via Downlink Control Information (DCI) scrambled by one of the C-RNTI or random access RNTI (RA-RNTI).

In example 107, the subject matter of any one or more of examples 102-106 optionally includes means for providing the indication signaling to support the low latency RA procedure via Radio Resource Control (RRC) signaling.

In example 108, the subject matter of example 107 optionally includes means for determining the selection of the low latency RA procedure by the UE based on a comparison of the PRACH preamble to a set of PRACH preambles specified for the low latency RA procedure.

In example 109, the subject matter of example 108 optionally includes means for determining the selection of the low-latency PRACH procedure by the UE based on a set of time and/or frequency resources for the first transmission.

In example 110, the subject matter of any one or more of examples 107-109 optionally includes means for indicating selection of a low latency RA procedure by based on one or more bits in a master information block or a system information block.

The foregoing detailed description includes references to the accompanying drawings, which form a part hereof. The drawings show, by way of illustration, specific embodiments which can be practiced. These embodiments are also referred to herein as "examples. Such examples may include elements other than those shown or described. However, examples are also contemplated that include the elements shown or described. Moreover, examples using any combination or permutation of those illustrated or described elements (or one or more aspects thereof) are also contemplated, either with respect to the specific examples illustrated or described herein (or with respect to other examples illustrated or described herein (or with respect to one or more aspects thereof).

The publications, patents, and patent documents referred to in this document are incorporated by reference in their entirety as if each had been incorporated by reference. The use in the reference document(s) incorporated by reference is in addition to the use in this document if there is inconsistent use between those documents incorporated by reference and this document; for incongruous inconsistencies, the usage in this document controls.

In this document, the terms "a" or "an" are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages 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 "including" and "in which" are used as the plain-english equivalents of the respective terms "comprising" and "wherein. Furthermore, in the following claims, the terms "comprises" and "comprising" are open-ended, i.e., a system, device, article, or process that comprises elements in addition to those listed after such terms is still considered to be within the scope of this claim. Furthermore, 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.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments may be utilized, as one of ordinary skill in the art would recognize upon reading the foregoing description. Abstract is intended to enable the reader to quickly ascertain the nature of the technical disclosure, e.g., so as to comply with US 37C.F.R § 1.72 (b). The abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing detailed description, various features may be combined together to simplify the present disclosure. However, the claims do not recite each and every feature disclosed herein, as embodiments may feature subsets of such features. Moreover, embodiments may include fewer features than are disclosed in the specific examples. Thus the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment. The scope of the embodiments disclosed herein is to be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims (20)

1. A method for communication, comprising:

by a user equipment, UE:

receiving cell-specific information comprising an indication of whether a cell supports a 2-step random access, RA, procedure, wherein the cell-specific information comprises two sets of RA preambles, wherein a first of the two sets of RA preambles is for a 2-step RA procedure and a second of the two sets of RA preambles is for a 4-step RA procedure;

determining to use the 2-step RA procedure;

transmitting a first message for a first transmission to the cell using the 2-step RA procedure over an unlicensed spectrum, wherein the first message comprises an RA preamble from the first group 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, and an identity of the UE; and

decoding a second transmission received on a physical downlink control channel, PDCCH, after the first transmission.

2. The method of claim 1, further comprising:

performing a listen before talk, LBT, procedure on one or more channels of the unlicensed spectrum.

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

4. The method of any of claims 1-3, wherein the message portion comprises a Media Access Control (MAC) portion comprising at least one MAC message, wherein the MAC message comprises at least one of the C-RNTI, the BSR information, or capabilities of the UE.

5. The method of claim 4, wherein the MAC message further comprises an identification of the UE.

6. The method of any of claims 4-5, wherein the message portion further comprises a Radio Resource Control (RRC) portion comprising an RRC message, wherein the RRC message comprises an identity of the UE.

7. The method of any of claims 4-6, wherein the capability of the UE comprises one of a layer 1UE capability, or a MAC UE capability.

8. The method of any of claims 1-7, wherein the message portion further comprises a Common Control Channel (CCCH) subheader.

9. The method of any of claims 1-7, further comprising:

transmitting a second message of a second transmission on the unlicensed spectrum in response to not receiving a UL grant based on the first transmission within a predetermined length of time after the first transmission, wherein the second message comprises a Physical Random Access Channel (PRACH) preamble and the message portion.

10. The method of 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 of any of claims 1-10, wherein the second transmission comprises the C-RNTI.

12. The method according to any of claims 1-10, wherein the second sending a scheduled random access response, RAR, and wherein the RAR comprises the C-RNTI and a non-temporary C-RNTIT-CRNTI.

13. A method for communication, comprising:

by the base station BS:

transmitting cell-specific information including an indication of whether a cell supports a 2-step random access, RA, procedure to a user equipment, UE, wherein the cell-specific information includes two sets of RA preambles, wherein a first of the two sets of RA preambles is for a 2-step RA procedure and a second of the two sets of RA preambles is for a 4-step RA procedure;

receiving a first message in a first transmission from the UE as part of a 2-step RA procedure performed by the UE, wherein the first message comprises an RA preamble from the first group 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, and an identity of the UE; and

a second message for a second transmission is transmitted on a physical downlink control channel, PDCCH.

14. The method of claim 13, further comprising:

a listen-before-talk, LBT, procedure is performed on one or more channels of the unlicensed spectrum.

15. The method of 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 of claim 13, further comprising:

the indication signaling for supporting the low-latency RA procedure is provided by radio resource control, RRC, signaling.

17. The method of claim 13, further comprising:

a respective frequency resource and/or code domain is assigned to each UE of a plurality of UEs to allow transmissions from the plurality of UEs to be multiplexed.

18. An apparatus, comprising:

at least one processor configured to cause a user equipment, UE, to perform the steps of the method of any of claims 1-12.

19. An apparatus, comprising:

at least one processor configured to cause a base station to perform the steps of the method of any of claims 13-17.

20. A computer program product comprising computer instructions which, when executed by one or more processors, perform the steps of the method of any one of claims 1 to 18.

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