Differentiated Random Access in New Radio

Abstract

A user equipment and method for improved random access between access points and stations in a wireless network is provided. In a wireless communication network, a user equipment includes a memory and at least one processor coupled to the memory, the processor receives multiple sets of values ​​of physical random access channel (PRACH) parameters, the multiple sets of PRACH parameters including a first set of values ​​of PRACH parameters associated with a first event that is a beam failure event and a second set of values ​​of PRACH parameters associated with a second event that is different from the first event, and performs a PRACH procedure based on the first event using the first set of values ​​of PRACH parameters associated with the first event.

Description

[Technical field]

[0001] Cross-reference to related art This application claims priority to U.S. Provisional Application No. 16 / 009,302, filed June 15, 2018, which claims priority to U.S. Provisional Application No. 62 / 521,273, filed June 16, 2017, U.S. Provisional Application No. 62 / 616,415, filed January 11, 2018, and U.S. Provisional Application No. 62 / 623,547, filed January 29, 2018, all of which are assigned to the assignee of this application and are expressly incorporated by reference in their entireties.

[0002] Certain aspects of the present disclosure relate generally to wireless communications, and more particularly, to differentiating Physical Random Access Channel (PRACH) procedures. [Background technology]

[0003] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems including LTE-Advanced, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

[0004] Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from the base station to the terminal, and the reverse link (or uplink) refers to the communication link from the terminal to the base station. This communication link may be established via a single-input single-output, multiple-input single-output, or a multiple-input multiple-output (MIMO) system.

[0005] A wireless communication network may include several base stations that can support communication for several wireless devices. The wireless devices may include user equipment (UE). Some UEs may be considered machine type communication (MTC) UEs, where an MTC UE may include a remote device that may communicate with a base station, another remote device, or some other entity. Machine type communication (MTC) may refer to communication involving at least one remote device on at least one end of the communication and may include a form of data communication involving one or more entities that does not necessarily require human interaction. An MTC UE may include a UE capable of MTC communication with an MTC server and / or other MTC devices, for example, through a public land mobile network (PLMN). [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] 3GPP TS 36.211 Summary of the Invention [Means for solving the problem]

[0007] The systems, methods, and devices of the present disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the present disclosure as expressed by the following claims, several features will now be briefly discussed. After considering this description, and especially after reading the section entitled "Description of the Preferred Embodiments," one will understand how the features of the present disclosure provide advantages including improved communications between access points and stations in a wireless network.

[0008] Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE), the method generally including: detecting a trigger for performing a Physical Random Access Channel (PRACH) procedure, selecting a set of values ​​of the PRACH parameters to use in the PRACH procedure from a plurality of sets of PRACH parameters based on the trigger, and performing the PRACH procedure using the selected set of values ​​of the PRACH parameters.

[0009] Certain aspects of the present disclosure provide a method for wireless communication by a base station (BS), the method generally including obtaining a plurality of sets of Physical Random Access Channel (PRACH) parameters, each set corresponding to one or more triggers of a PRACH procedure, and transmitting an indication of one of the sets of values ​​of the PRACH parameters and the corresponding triggers of the set.

[0010] Certain aspects of the present disclosure provide a method for wireless communication by a base station (BS), which generally includes providing an indication of a higher priority physical random access channel (PRACH) region, including a set of transmission resources, within a system bandwidth for transmitting a higher priority PRACH signal by a user equipment (UE), and determining a response window for the received PRACH signal based on receiving the PRACH signal over the set of transmission resources.

[0011] Certain aspects of the present disclosure provide a method for wireless communication by a user equipment (UE), the method generally including obtaining an indication of a random access response (RAR) window for a higher priority physical random access channel (PRACH) signal from a base station, and determining, based on the indication that the PRACH signal is a higher priority PRACH signal, a RAR window for the PRACH signal to be transmitted to a BS.

[0012] Certain aspects of the present disclosure provide an apparatus for wireless communication that generally includes a processor configured to detect a trigger for performing a Physical Random Access Channel (PRACH) procedure, select a set of values ​​of the PRACH parameters from a plurality of sets of PRACH parameters to use in the PRACH procedure based on the trigger, and cause the apparatus to perform the PRACH procedure using the selected set of values ​​of the PRACH parameters, and a memory coupled to the processor.

[0013] Certain aspects of the present disclosure provide an apparatus for wireless communication that generally includes a processor configured to obtain a plurality of sets of Physical Random Access Channel (PRACH) parameters, each set corresponding to one or more triggers of a PRACH procedure, and to cause the apparatus to transmit an indication of one of the sets of values ​​of the PRACH parameters and the corresponding trigger of the set, and a memory coupled to the processor.

[0014] Certain aspects of the present disclosure provide an apparatus for wireless communication. The apparatus generally includes a processor configured to cause the apparatus to provide an indication of a higher priority physical random access channel (PRACH) region including a set of transmission resources within a system bandwidth for transmitting a higher priority PRACH signal by a user equipment (UE), and to determine a response window for the received PRACH signal based on the apparatus receiving the PRACH signal over the set of transmission resources, and a memory coupled to the processor.

[0015] Certain aspects of the present disclosure provide an apparatus for wireless communication. The apparatus generally includes a processor configured to obtain an indication of a random access response (RAR) window for a higher priority physical random access channel (PRACH) signal from a base station, and determine, based on the indication that the PRACH signal is a higher priority PRACH signal, a RAR window for the PRACH signal to be transmitted to a BS, and a memory coupled to the processor.

[0016] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for detecting a trigger for performing a Physical Random Access Channel (PRACH) procedure, means for selecting, based on the trigger, a set of values ​​of the PRACH parameters to use in the PRACH procedure from a plurality of sets of PRACH parameters, and means for performing the PRACH procedure using the selected set of values ​​of the PRACH parameters.

[0017] Certain aspects of the disclosure provide an apparatus for wireless communication that generally includes means for obtaining a plurality of sets of physical random access channel (PRACH) parameters, each set corresponding to one or more triggers of a PRACH procedure, and means for transmitting an indication of one of the sets of values ​​of the PRACH parameters and the corresponding trigger of the set.

[0018] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for providing an indication of a higher priority physical random access channel (PRACH) region including a set of transmission resources within a system bandwidth for transmitting a higher priority PRACH signal by a user equipment (UE), and means for determining a response window for the received PRACH signal based on receiving the PRACH signal over the set of transmission resources.

[0019] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for obtaining an indication of a random access response (RAR) window for a higher priority physical random access channel (PRACH) signal from a base station, and means for determining, based on the indication that the PRACH signal is a higher priority PRACH signal, a RAR window for the PRACH signal transmitted to a BS.

[0020] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications. The computer-readable medium generally includes instructions that, when executed by a processor, cause the processor to perform operations, the operations generally including: detecting a trigger to perform a Physical Random Access Channel (PRACH) procedure, selecting a set of values ​​of the PRACH parameters from a plurality of sets of PRACH parameters to use in the PRACH procedure based on the trigger, and causing a device to perform the PRACH procedure using the selected set of values ​​of the PRACH parameters.

[0021] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications. The computer-readable medium includes instructions that, when executed by a processor, cause the processor to perform operations, generally including obtaining a plurality of sets of Physical Random Access Channel (PRACH) parameters, each set corresponding to one or more triggers of a PRACH procedure, and causing a device to transmit an indication of one of the sets of values ​​of the PRACH parameters and the corresponding trigger of the set.

[0022] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications. The computer-readable medium includes instructions that, when executed by a processor, cause the processor to perform operations, generally including providing an indication of a higher priority physical random access channel (PRACH) region, including a set of transmission resources, within a system bandwidth for transmitting a higher priority PRACH signal by a user equipment (UE), and determining a response window for the received PRACH signal based on receiving the PRACH signal over the set of transmission resources.

[0023] Certain aspects of the present disclosure provide a computer-readable medium for wireless communications. The computer-readable medium includes instructions that, when executed by a processor, cause the processor to perform operations, generally including obtaining an indication of a random access response (RAR) window for a higher priority physical random access channel (PRACH) signal from a base station, and determining a RAR window for the PRACH signal to be transmitted to a BS based on the indication that the PRACH signal is a higher priority PRACH signal.

[0024] Numerous other aspects are provided, including methods, apparatus, systems, computer program products, and processing systems.

[0025] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of what has been briefly summarized above may be made by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the description may lead to other equally effective embodiments, and that the accompanying drawings illustrate only some typical embodiments of the present disclosure, and therefore should not be considered as limiting the scope of the present disclosure. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a block diagram conceptually illustrating an example wireless communication network, in accordance with certain aspects of the present disclosure. [Diagram 2] FIG. 1 is a block diagram conceptually illustrating an example of an evolved Node B (eNB) in communication with a user equipment (UE) in a wireless communication network, in accordance with certain aspects of the present disclosure. [Diagram 3] FIG. 1 is a block diagram conceptually illustrating an example frame structure of a particular Radio Access Technology (RAT) for use in a wireless communications network, in accordance with certain aspects of the present disclosure. [Figure 4] FIG. 1 illustrates an example subframe format for a downlink with a normal cyclic prefix, in accordance with certain aspects of the present disclosure. [Figure 5A] FIG. 2 illustrates an example of MTC coexistence in a wideband system such as LTE, in accordance with certain aspects of the present disclosure. [Figure 5B] FIG. 2 illustrates an example of MTC coexistence in a wideband system such as LTE, in accordance with certain aspects of the present disclosure. [Figure 6] A diagram illustrating an example mapping of DL narrowband regions to UL narrowband regions in accordance with certain aspects of the present disclosure. [Figure 7] FIG. 2 illustrates a schematic diagram of an example Physical Random Access Channel (PRACH) signal, in accordance with certain aspects of the present disclosure. [Figure 8]FIG. 1 illustrates example operations for wireless communication that may be performed by a UE in accordance with certain aspects of the present disclosure. [Figure 9] FIG. 1 illustrates example operations for wireless communication that may be performed by a BS in accordance with certain aspects of the present disclosure. [Figure 10A] FIG. 2 illustrates a schematic diagram of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure. [Figure 10B] FIG. 2 illustrates a schematic diagram of a set of resources reserved for a PRACH signal, in accordance with certain aspects of the present disclosure. [Figure 11] FIG. 1 illustrates example operations for wireless communication that may be performed by a BS in accordance with certain aspects of the present disclosure. [Figure 12] FIG. 1 illustrates example operations for wireless communication that may be performed by a UE in accordance with certain aspects of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Aspects of the present disclosure provide techniques and apparatus for differentiating physical random access channel (PRACH) procedures for user equipment (UE) served by a network, such as mobile phones, low-cost (LC) machine type communication (MTC) devices, and LC enhanced MTC (eMTC) devices. According to aspects of the present disclosure, a network (e.g., a base station of the network) may configure a UE with a set of parameters for performing a physical random access channel (PRACH) procedure, allowing a PRACH procedure by the UE to be differentiated from other PRACH procedures, e.g., by other UEs or by the same UE at other times. The UE may be triggered to perform a PRACH procedure (e.g., a random access procedure) and may select a set of parameter values ​​to use in performing the PRACH procedure based on the trigger.

[0028] The techniques described herein may be used for various wireless communication networks, such as Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, Single Carrier FDMA (SC-FDMA) networks, etc. The terms "network" and "system" are often used interchangeably. A CDMA network may implement radio technologies such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes Wideband CDMA (W-CDMA), Time Division Synchronous CDMA (TD-SCDMA), and other variants of CDMA. cdma2000 covers IS-2000, IS-95, and IS-856 standards. A TDMA network may implement radio technologies such as Global System for Mobile Communications (GSM). An OFDMA network may implement radio technologies such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are parts of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD), are releases of UMTS that use E-UTRA, which employs OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents by an organization named "3rd Generation Partnership Project" (3GPP). cdma2000 and UMB are described in documents by an organization named "3rd Generation Partnership Project 2" (3GPP2). One example of an emerging telecommunications standard is New Radio (NR), e.g., 5G radio access. NR is a set of extensions to the LTE mobile standard promulgated by 3GPP.NR is designed to improve spectral efficiency, lower costs, improve services, take advantage of new spectrum, and better support mobile broadband Internet access by better integrating with other open standards that use OFDMA with cyclic prefix (CP) on the downlink (DL) and uplink (UL), as well as supporting beamforming, MIMO antenna technology, and carrier aggregation. Some next-generation NR or 5G networks may include several base stations, each simultaneously supporting communication for multiple communication devices such as UEs. In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB). In another example (e.g., in next generation or 5G networks), a wireless multiple-access communication system may include several distributed units (e.g., Edge Units (EU), Edge Nodes (EN), Radio Heads (RH), Smart Radio Heads (SRH), Transmit Receiving Points (TRPs), etc.) in communication with several central units (e.g., Central Nodes (CN), Access Node Controllers (ANCs), etc.), and a set of one or more distributed units in communication with the central units may define an access node (e.g., New Radio Base Station (NR BS), New Radio Node B (NR NB), network node, gNB, etc.). A base station or DU may communicate with a set of UEs on a downlink channel (e.g., for transmissions from the base station or to the UEs) and an uplink channel (e.g., for transmissions from the UEs to the base station or distributed units). The techniques described herein may be used for the wireless networks and radio technologies mentioned above, as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below with respect to LTE / LTE-A, and LTE / LTE-A terminology is used in much of the description below. LTE and LTE-A are commonly referred to as LTE.

[0029] FIG. 1 illustrates an example wireless communication network 100 having a base station (BS) and user equipment (UE) in which aspects of the present disclosure may be practiced.

[0030] For example, one or more paging procedure extensions for a particular UE (e.g., LC MTC UE, LC eMTC UE, etc.) in the wireless communication network 100 may be supported. According to the techniques presented herein, the BSs and LC UEs in the wireless communication network 100 may be able to determine, from the available system bandwidth supported by the wireless communication network 100, which narrowband regions the LC UEs should monitor for bundled paging messages transmitted from the BSs in the wireless communication network 100. Also, according to the techniques presented herein, the BSs and / or LC UEs in the wireless communication network 100 may be able to determine and / or adapt the bundling size of the paging messages based on one or more triggers in the wireless communication network 100.

[0031] The wireless communication network 100 may be an LTE network or some other wireless network. The wireless communication network 100 may include several evolved Node Bs (eNBs) 110 and other network entities. An eNB is an entity that communicates with user equipment (UE) and may also be referred to as a base station, a Node B, an access point (AP), etc. Each eNB may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of ​​an eNB and / or an eNB subsystem that serves this coverage area, depending on the context in which the term is used.

[0032] An eNB may provide communication coverage for a macro cell, a pico cell, a femto cell, and / or other types of cells. A macro cell may cover a relatively large geographic area (e.g., a few kilometers in radius) and may allow unrestricted access by UEs with a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG)). An eNB for a macro cell may be referred to as a macro eNB. An eNB for a pico cell may be referred to as a pico eNB. An eNB for a femto cell may be referred to as a femto eNB or a Home eNB (HeNB). 1, eNB 110a may be a macro eNB for macro cell 102a, eNB 110b may be a pico eNB for pico cell 102b, and eNB 110c may be a femto eNB for femto cell 102c. An eNB may support one or multiple (e.g., three) cells. The terms “eNB,” “base station,” and “cell” may be used interchangeably herein.

[0033] The wireless communication network 100 may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., an eNB or UE) and send a transmission of data to a downstream station (e.g., a UE or eNB). A relay station may also be a UE that can relay a transmission for other UEs. In the example shown in FIG. 1, a relay (station) eNB 110d may communicate with macro eNB 110a and UE 120d to facilitate communication between eNB 110a and UE 120d. A relay station may also be referred to as a relay eNB, a relay base station, a relay, etc.

[0034] The wireless communication network 100 may be a heterogeneous network including different types of eNBs, e.g., macro eNBs, pico eNBs, femto eNBs, relay eNBs, etc. These different types of eNBs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless communication network 100. For example, a macro eNB may have a high transmit power level (e.g., 5-40 W), while the pico eNBs, femto eNBs, and relay eNBs may have lower transmit power levels (e.g., 0.1-2 W).

[0035] A network controller 130 may couple to a set of eNBs and provide coordination and control for these eNBs. The network controller 130 may communicate with the eNBs via a backhaul. The eNBs may also communicate with each other directly or indirectly, for example, via a wireless or wireline backhaul.

[0036] The UEs 120 (e.g., 120a, 120b, 120c) may be distributed throughout the wireless communications network 100, and each UE may be fixed or mobile. A UE may also be referred to as an access terminal, terminal, mobile station (MS), subscriber unit, station (STA), etc. A UE may be a cellular phone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a smartphone, a netbook, a smartbook, an ultrabook, a navigation device, a gaming device, a camera, a vehicular device, a drone, a robot / robotic device, a wearable device (e.g., a smart watch, a smart clothing, a smart wristband, a smart ring, a smart bracelet, smart glasses, virtual reality goggles), etc. MTC UEs include devices such as sensors, meters, monitors, location tags, drones, trackers, robot / robotic devices, etc. The UE may be implemented as any Internet of Things (IoE) or Internet of Things (IoT) (e.g., Narrowband IoT (NB-IoT)) device.

[0037] One or more UEs 120 in the wireless communication network 100 (e.g., an LTE network) may also be low-cost (LC), low-data-rate devices, such as, for example, LC MTC UEs, LC eMTC UEs, etc. An LC UE may coexist with legacy and / or advanced UEs in an LTE network and have one or more capabilities that are limited compared to other UEs (e.g., non-LC UEs) in the wireless network. For example, compared to legacy and / or advanced UEs in an LTE network, an LC UE may operate with one or more of the following: reduced maximum bandwidth (relative to legacy UEs), a single receive radio frequency (RF) chain, reduced peak rates, reduced transmit power, rank-1 transmission, half-duplex operation, etc. As used herein, devices with limited communication resources, such as MTC devices, eMTC devices, etc., are generally referred to as LC UEs. Similarly, legacy devices, such as legacy and / or advanced UEs (e.g., in LTE), are generally referred to as non-LC UEs.

[0038] 2 is a block diagram of a design of a BS / eNB 110 and a UE 120, which may be one of the BS / eNBs 110 and one of the UEs 120, respectively, in FIG 1. BS 110 may be equipped with T antennas 234a through 234t, and UE 120 may be equipped with R antennas 252a through 252r, where in general T≧1 and R≧1.

[0039] At the BS 110, the transmit processor 220 may receive data for one or more UEs from the data source 212, select one or more modulation and coding schemes (MCS) for each UE based on a channel quality indicator (CQI) received from the UE, process (e.g., encode and modulate) the data for each UE based on the MCS selected for the UE, and provide data symbols to all UEs. The transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, higher layer signaling, etc.) and provide overhead symbols and control symbols. The transmit processor 220 may also generate reference symbols for reference signals (e.g., a common reference signal (CRS)) and synchronization signals (e.g., a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)). The transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on ​​the data symbols, control symbols, overhead symbols, and / or reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each MOD 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. The T downlink signals from the modulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

[0040] At the UE 120, antennas 252a-252r may receive downlink signals from the BS 110 and / or other BSs and may provide received signals to demodulators (DEMODs) 254a-254r, respectively. Each DEMOD 254 may condition (e.g., filter, amplify, downconvert, and digitize) its received signal to obtain input samples. Each DEMOD 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all R demodulators 254a-254r, perform MIMO detection on the received symbols, if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate and decode) the detected symbols and provide decoded data for the UE 120 to a data sink 260 and provide decoded control and system information to the controller / processor 280. The channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), a CQI, and the like.

[0041] On the uplink, at the UE 120, the transmit processor 264 may receive and process data from the data source 262 and control information (e.g., for reports comprising RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280. The processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by MODs 254a-254r (e.g., for SC-FDM, OFDM, etc.), and transmitted to the BS 110. At the BS 110, uplink signals from the UE 120 and other UEs may be received by the antennas 234, processed by the DEMOD 232, detected by a MIMO detector 236 if applicable, and further processed by the receive processor 238 to obtain decoded data and control information sent by the UE 120. The receive processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller / processor 240. The BS 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292.

[0042] The controllers / processors 240 and 280 may direct operation at the BS 110 and the UE 120, respectively. For example, the controller / processor 240 and / or other processors and modules at the BS 110 may perform or direct other processes for the operations shown in FIG. 9 and / or the techniques described herein. Similarly, the controller / processor 280 and / or other processors and modules at the UE 120 may perform or direct processes for the operations shown in FIG. 8 and / or the techniques described herein. The memories 242 and 282 may store data and program codes for the BS 110 and the UE 120, respectively. The scheduler 246 may schedule UEs for data transmission on the downlink and / or uplink.

[0043] FIG. 3 illustrates an example frame structure 300 for FDD in LTE. A transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes with indices from 0 to 9. Each subframe may include two slots. Thus, each radio frame may include 20 slots with indices from 0 to 19. Each slot may include L symbol periods, e.g., 7 symbol periods for a normal cyclic prefix (as shown in FIG. 2) or 6 symbol periods for an extended cyclic prefix. The 2L symbol periods in each subframe may be assigned indices from 0 to 2L-1.

[0044] In LTE, an eNB may transmit a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink in the center 1.08 MHz of the system bandwidth for each cell supported by the eNB. The PSS and SSS may be transmitted in symbol periods 6 and 5 in subframes 0 and 5 of each radio frame with a normal cyclic prefix, respectively, as shown in FIG. 3. The PSS and SSS may be used by the UE for cell search and cell acquisition. The eNB may transmit a cell-specific reference signal (CRS) across the system bandwidth for each cell supported by the eNB. The CRS may be transmitted in several symbol periods of each subframe and may be used by the UE to perform channel estimation, channel quality measurement, and / or other functions. The eNB may also transmit a physical broadcast channel (PBCH) in symbol periods 0-3 in slot 1 of some radio frames. The PBCH may carry several system information. The eNB may transmit other system information, such as a system information block (SIB) on a physical downlink shared channel (PDSCH) in some subframes. The eNB may transmit control information / data on a physical downlink control channel (PDCCH) in the first B symbol periods of a subframe, where B may be configurable per subframe. The eNB may transmit traffic data and / or other data on the PDSCH in the remaining symbol periods of each subframe. The eNB may transmit control information / data on an enhanced physical downlink control channel (EPDCCH) in any symbol period of a subframe.

[0045] The PSS, SSS, CRS, and PBCH in LTE are described in the published 3GPP TS 36.211, entitled "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation."

[0046] Figure 4 shows two example subframe formats 410 and 420 for the downlink with a normal cyclic prefix. The time-frequency resources available for the downlink may be partitioned into resource blocks. Each resource block may cover 12 subcarriers in one slot and may contain several resource elements. Each resource element may cover one subcarrier in one symbol period and may be used to send one modulation symbol, which may be real or complex valued.

[0047] Subframe format 410 may be used for an eNB with two antennas. The CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11. A reference signal is a signal that is known a priori by the transmitter and receiver and may also be referred to as a pilot. The CRS is a cell-specific reference signal that is generated, for example, based on a cell identity (ID). In FIG. 4, for a given resource element with label Ra, modulation symbols may be transmitted from antenna a on that resource element and no modulation symbols may be transmitted from other antennas on that resource element. Subframe format 420 may be used for an eNB with four antennas. The CRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7, and 11 and from antennas 2 and 3 in symbol periods 1 and 8. For both subframe formats 410 and 420, the CRS may be transmitted on evenly spaced subcarriers that may be determined based on the cell ID. Different eNBs may transmit their CRS on the same or different subcarriers depending on their cell ID. For both subframe formats 410 and 420, resource elements not used for the CRS may be used to transmit data (eg, traffic data, control data, and / or other data).

[0048] An interlace structure may be used for each of the downlink and uplink for FDD in LTE. For example, Q interlaces with indices from 0 to Q-1 may be defined, where Q may be equal to 4, 6, 8, 10, or some other value. Each interlace may include subframes spaced apart by Q frames. In particular, interlace q may include subframes q, q+Q, q+2Q, etc., where q∈{0, ..., Q-1}.

[0049] Wireless networks may support hybrid automatic repeat request (HARQ) for data transmissions on the downlink and uplink. For HARQ, a transmitter (e.g., eNB 110) may send one or more transmissions of a packet until the packet is correctly decoded by a receiver (e.g., UE 120) or some other termination condition is encountered. For synchronous HARQ, all transmissions of a packet may be sent in subframes of a single interlace. For asynchronous HARQ, each transmission of a packet may be sent in any subframe.

[0050] A UE may be located within the coverage of multiple eNBs. One of these eNBs may be selected to serve the UE. The serving eNB may be selected based on various criteria such as received signal strength, received signal quality, path loss, etc. The received signal quality may be quantified by a signal-to-interference-and-noise ratio (SINR), or a reference signal received quality (RSRQ), or some other metric. The UE may operate in a dominant interference scenario in which the UE may observe high interference from one or more interfering eNBs.

[0051] As mentioned above, one or more UEs in a wireless communications network (e.g., wireless communications network 100) may be devices, such as LC UEs, that have limited communications resources compared to other (non-LC) devices in the wireless communications network.

[0052] For example, in some systems in LTE Rel-13, LC UEs may be restricted to a particular narrowband allocation (e.g., of no more than six resource blocks (RBs)) within the available system bandwidth. However, LC UEs may be able to retune (e.g., operate and / or camp) on a different narrowband region within the available system bandwidth of the LTE system, e.g., to coexist within the LTE system.

[0053] As another example of coexistence in an LTE system, an LC UE may be capable of (repeatedly) receiving a legacy physical broadcast channel (PBCH) (e.g., an LTE physical channel that typically carries parameters that may be used for initial access to a cell) and supporting one or more legacy physical random access channel (PRACH) formats. For example, an LC UE may be capable of receiving a legacy PBCH with one or more additional repetitions of the PBCH across multiple subframes. As another example, an LC UE may be capable of transmitting one or more repetitions of a PRACH (e.g., with one or more supported PRACH formats) to an eNB in ​​an LTE system. The PRACH may be used to identify the LC UE. Also, the number of repeated PRACH attempts may be configured by the eNB.

[0054] An LC UE may also be a link budget limited device and may operate in different operating modes (e.g., with different amounts of repeated messages transmitted to and from the LC UE) based on its link budget limitations. For example, in some cases, an LC UE may operate in a normal coverage mode with little or no repetition (e.g., the amount of repetition required for the UE to successfully receive and / or transmit a message may be small or no repetition may even be necessary). Alternatively, in some cases, an LC UE may operate in a coverage extension (CE) mode with a large amount of repetition. For example, for a 328-bit payload, an LC UE in CE mode may require 150 or more repetitions of the payload to successfully receive it.

[0055] In some cases, e.g., even in LTE Rel-13, an LC UE may have limited capabilities regarding the reception of its broadcast and unicast transmissions. For example, the maximum transport block (TB) size of a broadcast transmission received by an LC UE may be limited to 1000 bits. In addition, in some cases, an LC UE may not be able to receive more than one unicast TB in a subframe. In some cases (e.g., in both CE and normal modes described above), an LC UE may not be able to receive more than one broadcast TB in a subframe. Furthermore, in some cases, an LC UE may not be able to receive both unicast and broadcast TBs in a subframe.

[0056] For MTC, LC UEs coexisting in an LTE system may also support new messages for some procedures, such as paging, random access procedures, etc. (e.g., as opposed to conventional messages used in LTE for these procedures). In other words, these new messages for paging, random access procedures, etc. may be separate from messages used for similar procedures associated with non-LC UEs. For example, compared to conventional paging messages used in LTE, LC UEs may be able to monitor and / or receive paging messages that non-LC UEs may not be able to monitor and / or receive. Similarly, compared to conventional random access response (RAR) messages used in conventional random access procedures, LC UEs may be able to receive RAR messages that may also not be able to be received by non-LC UEs. New paging and RAR messages associated with LC UEs may also be repeated (e.g., "bundled") one or more times. In addition, different numbers of repetitions of new messages (e.g., different bundling sizes) may be supported.

[0057] As mentioned above, MTC and / or eMTC operations may be supported in a wireless communications network (e.g., coexisting with LTE or some other RAT). Figures 5A and 5B, for example, show an example of how an LC UE in MTC operation may coexist in a wideband system such as LTE.

[0058] As shown in the example frame structure of FIG. 5A, subframes 510 associated with MTC and / or eMTC operation may be time division multiplexed (TDM) with regular subframes 520 associated with LTE (or some other RAT).

[0059] Additionally or alternatively, as shown in the exemplary frame structure of FIG. 5B, one or more narrowband regions 560, 562 used by LC UEs in MTC may be frequency division multiplexed within the wider bandwidth 550 supported by LTE. Multiple narrowband regions, each spanning a bandwidth totaling six RBs or less, may be supported for MTC and / or eMTC operations. In some cases, each LC UE in MTC operation may operate within one narrowband region at a time (e.g., at 1.4 MHz or six RBs). However, an LC UE in MTC operation may retune to another narrowband region within the wider system bandwidth at any given time. In some examples, multiple LC UEs may be served by the same narrowband region. In other examples, multiple LC UEs may be served by different narrowband regions (e.g., each narrowband region spanning six RBs). In still other examples, different combinations of LC UEs may be served by one or more of the same narrowband regions and / or one or more different narrowband regions.

[0060] LC UEs may operate (e.g., monitor / receive / transmit) within the narrowband region for various different operations. For example, as shown in FIG. 5B, a first narrowband region 560 (e.g., spanning only six RBs of wideband data) of subframe 552 may be monitored by one or more LC UEs for either PSS, SSS, PBCH, MTC signaling, or paging transmissions from a BS in a wireless communication network. Regions 556 and 558 may be used by the BS to transmit data to other UEs (e.g., non-LC UEs). Also as shown in FIG. 5B, a second narrowband region 562 (e.g., also spanning only six RBs of wideband data) of subframe 554 may be used by the BS to transmit RACH messages or data previously configured in signaling by the BS to one or more of the LC UEs and / or other LC UEs. The LC UEs may retune to the second narrowband region for reception after monitoring the first narrowband region. Region 559 may be used by the BS to transmit data to other UEs (eg, non-LC UEs).

[0061] Although the examples described herein assume a narrowband of 6 RBs, those skilled in the art will recognize that the techniques presented herein may also be applied to narrowband regions of different sizes.

[0062] As mentioned above, in some systems, such as, for example, LTE Rel-12, narrowband operation for MTC (e.g., eMTC) may be supported. A cell supporting narrowband operation for MTC may have different system bandwidths for downlink (DL) and uplink (UL) operations. A cell with different DL and UL system bandwidths (SB) may organize the DL system bandwidth into narrowband regions in a manner different from the manner used to organize the UL system bandwidth into narrowband regions. Thus, aspects of the present disclosure provide techniques for organizing the DL and UL system bandwidths into narrowband regions.

[0063] A cell supporting narrowband operation for MTC UEs and legacy UEs may receive legacy PUCCH transmissions from the legacy UEs. The legacy PUCCH transmissions may be transmitted at either or both edges of the cell's UL system bandwidth. Thus, aspects of the present disclosure provide techniques to reserve transmission resources contained in the UL narrowband region for use by the legacy PUCCH transmissions. Similar reservations may also be applied to DL narrowband regions for use by other legacy DL signals or channels.

[0064] A cell supporting narrowband operation for MTC may also support transmission of a sounding reference signal (SRS). The currently defined minimum bandwidth for transmitting an SRS is four RBs. However, as discussed above, the bandwidth of the narrowband region is six RBs. The fact that six RBs are not divisible by four RBs presents a challenge in managing SRS transmission using four RBs in a 6-RB-based narrowband operation. Thus, aspects of the present disclosure provide techniques for allocating transmission resources for transmitting an SRS in a cell supporting narrowband operation (e.g., for MTC).

[0065] A cell operating in FDD may have a DL system bandwidth that is a different size than the cell's UL system bandwidth. For example, a cell may perform DL operations in a 10 MHz system bandwidth and UL operations in a 5 MHz system bandwidth. To support MTC operations and MTC UEs, a cell may organize the DL and UL system bandwidths into narrowband or narrowband regions. The eNB or other BS controlling the cell may assign a DL narrowband region to the MTC UE for the MTC UE to monitor signals from the eNB. Similarly, the eNB (or other BS) may assign a UL narrowband region to the MTC UE for use when the MTC UE transmits UL signals. In this example, the cell may organize the UL system bandwidth into four UL narrowband regions, while organizing the DL system bandwidth into eight DL narrowband regions.

[0066] When a BS (e.g., an eNB or a cell) supports MTC UEs with the cell's DL and UL system bandwidths organized into narrowband regions, the BS may establish a mapping between the DL and UL narrowband regions such that assigning a DL narrowband region to an MTC UE implies assignment of a UL narrowband region to that MTC UE. Having the mapping allows the BS to simplify resource scheduling within the cell, e.g., the BS can anticipate ACK / NAKs of transmissions on the corresponding UL narrowband region to an MTC UE on a DL narrowband region. Similarly, an MTC UE monitors DL transmissions on the assigned DL narrowband region for that MTC UE and responds with transmissions on the corresponding UL narrowband region.

[0067] According to an aspect of the present disclosure, a technique is provided for mapping UL and DL narrowband regions by a BS. The BS may determine the minimum size of the UL and DL system bandwidths supported by the BS, determine the number of narrowband regions that can be organized into the determined size, and then organize both the DL and UL system bandwidths into that number of narrowband regions. The BS may then map each DL narrowband region to one UL narrowband region. For example, a cell may perform DL operations in a 10 MHz system bandwidth and UL operations in a 5 MHz system bandwidth. In this example, the BS may determine that the minimum size of the UL and DL system bandwidths is 5 MHz, and then determine that the BS can organize four narrowband regions in the 5 MHz system bandwidth. Still in this example, the BS may then organize four DL narrowband regions in the DL system bandwidth and four UL narrowband regions in the UL system bandwidth, and map each DL narrowband region to one UL narrowband region.

[0068] FIG. 6 illustrates an example mapping 600 of DL narrowband regions to UL narrowband regions, as described above. Such a mapping may be used by the eNB 110a of FIG. 1. Although FIG. 6 illustrates DL system bandwidth 610 and UL system bandwidth 650 seemingly in the same frequency range, the DL system bandwidth and UL system bandwidth are in different frequency ranges in a cell using FDD. The DL system bandwidth 610 is 10 MHz or 50 RBs wide, and the UL system bandwidth 650 is 5 MHz or 25 RBs wide. A BS supporting an MTC UE while operating the DL system bandwidth 610 and the UL system bandwidth 650 may determine that the UL system bandwidth 650 is smaller than the DL system bandwidth 610 (the 5 MHz size of the UL system bandwidth 650 is the minimum size of the UL system bandwidth 650 and the DL system bandwidth 610). The BS may then determine that it can organize four narrowband regions 652, 654, 656, and 658 from the UL system bandwidth 650. The BS may then determine to organize four narrowband regions from the DL system bandwidth and organize DL narrowband regions 612, 614, 616, and 618 from the DL system bandwidth. The BS may then map DL narrowband region 612 to UL narrowband region 652, DL narrowband region 614 to UL narrowband region 654, DL narrowband region 616 to UL narrowband region 656, and DL narrowband region 618 to UL narrowband region 658.

[0069] Exemplary Differentiated Random Access in New Radio According to aspects of the disclosure, a network (e.g., a base station of the network) may configure a UE with a set of parameters for performing a Physical Random Access Channel (PRACH) procedure, allowing a PRACH procedure by the UE to be differentiated from other PRACH procedures, e.g., by other UEs or by the same UE at other times. The UE may be triggered to perform a PRACH procedure (e.g., a random access procedure) and may select a set of parameters to use in performing the PRACH procedure based on the trigger.

[0070] According to aspects of the present disclosure, a random access procedure in NR may be triggered for at least the following events: (1) Initial access from RRC_IDLE (2) RRC Connection Re-establishment Procedure (3) Handover (4) For example, when the UL synchronization status is "unsynchronized", DL data arrives during RRC_CONNECTED, requesting a random access procedure. (5) UL data arrives during RRC_CONNECTED, requesting a random access procedure, for example when the UL synchronization status is "unsynchronized" or there are no PUCCH resources available for a Scheduling Request (SR). (6) Transition from RRC_INACTIVE to RRC_CONNECTED (7) Recovering a failed serving beam on a cell

[0071] In an aspect of the present disclosure, a random access procedure in a secondary cell (SCell) in NR may be supported when multiple tracking areas (TA) are supported by the network, such as in LTE.

[0072] According to aspects of the present disclosure, the random access procedure in NR is performed at least on the primary (PCell) upon Secondary Cell Group (SCG) addition and / or modification, if indicated, or upon DL and / or UL data arrival when the UE is in RRC_CONNECTED state and a random access procedure needs to be performed, e.g., if the UE is unsynchronized. The UE-initiated random access procedure is only performed on the PSCell for the SCG, e.g., in LET.

[0073] In aspects of the present disclosure, at most one random access procedure may be ongoing at any one time in a medium access control (MAC) entity, eg, a MAC entity of a UE.

[0074] When a UE needs to connect to a cell to which the UE is not currently connected, the UE and the cell engage in an exchange of messages called a physical random access channel (PRACH) procedure. In an exemplary PRACH procedure, the UE transmits a physical random access channel (PRACH) signal (sometimes referred to as a preamble or message 1 (Msg1) of the PRACH procedure) in a set of transmission resources reserved for the PRACH signal (sometimes referred to as a PRACH region), and the cell then responds to the PRACH signal with a random access response (RAR) message (sometimes referred to as message 2 (Msg2) of the PRACH procedure) carried on a downlink shared channel (DL-SCH). The UE responds to the RAR message with an RRC connection request message (sometimes referred to as message 3 (Msg3) of the PRACH procedure), and the cell responds to Msg3 with a contention resolution message (sometimes referred to as message 4 (Msg4) of the PRACH procedure). The UE may then be connected to the cell.

[0075] In current (e.g., LTE Rel-12) wireless technologies, a PRACH signal transmitted by an MTC device includes a first group of four symbols using a first hopping pattern and a second group of four symbols using the first hopping pattern but offset from the first group by a random group hopping value.

[0076] FIG. 7 illustrates an exemplary PRACH signal 700 according to an aspect of the present disclosure. Four symbols 702a-702d in a first group 704a are transmitted (e.g., by a UE), then random group hopping is applied and a second group 704b of symbols 702e-702h with the same hopping pattern as in the first group is transmitted (e.g., by a UE). Curve 706 illustrates the correspondence between symbols 702a in group 704a and symbols 702e in group 704b. Similarly, symbol 702b corresponds to symbol 702f, symbol 702c corresponds to symbol 702g, and symbol 702d corresponds to symbol 702h.

[0077] The tone spacing of a PRACH signal (e.g., PRACH signal 700 shown in FIG. 7) may be 3.75 kHz. Symbols in the PRACH signal may use a cyclic prefix (CP) length of 66.7 microseconds (μs) or 266.7 μs, both of which are different from the CP length used for data transmission in LTE systems.

[0078] When a UE initiates a random access procedure, the UE randomly selects one resource (e.g., a tone) from the resources reserved in the cell for PRACH signal transmission and transmits the PRACH signal using that resource. The UE may determine which resources in the cell are reserved for the PRACH signal by receiving and decoding one or more system information blocks (SIBs) transmitted by the cell.

[0079] In LTE baseline, all UEs perform the same random access procedure with the same set of configured parameters. No differentiation or prioritization is available. However, there are several use cases with NR that show that NR provides differentiated access, according to aspects of the present disclosure.

[0080] According to aspects of the disclosure, NR will support different types of services, some of which may have different objectives for their access. For example, the network may prefer to give faster access to ultra-reliable and low-latency communications (URLLC) services than other services, and eMTC services may aim to minimize the amount of energy consumed by eMTC UEs during their access.

[0081] In aspects of the present disclosure, network slicing may be supported in NR. The main feature of network slicing (sometimes simply referred to as "slicing") is differentiated transport services over the same physical network. One aspect of differentiated services may include differentiated treatment during access to the network. For example, a premium user group may require faster access and lower blocking rates than general users.

[0082] According to aspects of the disclosure, different types of random access events may require different access delays, for example, a UE in RCC_CONNECTED state attempting to use random access to resynchronize (e.g., after becoming unsynchronized) may be given higher priority than a UE in RRC_IDLE state attempting to gain initial access.

[0083] According to aspects of the present disclosure, even if differentiation is required, there is no fundamental difference in the way the random access procedure is performed from a procedural point of view. Furthermore, no use cases are defined that call for random access to be performed in the same numerology as that used in connected mode. For example, it has been agreed that a quality of service (QoS) request for URLLC by the UE does not begin until the UE is connected. To simplify implementation, it may be desirable to have a common random access procedure for all types of services or random access events in NR. The random access procedure specified in the LTE baseline is mature and flexible, and therefore using the LTE random access procedure as a baseline for NR may be a good choice.

[0084] According to aspects of the present disclosure, partitioning of PRACH resources (e.g., preamble, time / frequency) may not be a good approach to implement differentiated random access because partitioning of PRACH resources may not be a scalable approach. The more service requirements to be met, the finer the PRACH resources are partitioned. If the PRACH resources are partitioned into small pieces, access contention may increase rapidly.

[0085] In aspects of the present disclosure, the parameterization of the baseline PRACH procedure to support differentiation does not require any changes to the design of the PRACH procedure or the partitioning of the PRACH resources, and may be a more efficient and scalable approach to support differentiation than PRACH resource partitioning.

[0086] 8 illustrates example operations 800 for wireless communication that may be performed by a UE (e.g., UE 120a of FIG. 1) in accordance with aspects of the disclosure. The operations 800 may be performed by the UE to perform a PRACH procedure differentiated from other PRACH procedures (e.g., by other UEs or by a UE at another time).

[0087] The operations 800 begin at block 802, where a UE detects a trigger to perform a physical random access channel (PRACH) procedure. For example, UE 120a may detect that the UE has entered an RRC disconnected state, but in a cell served by BS 110a, the UE is triggered to perform a PRACH procedure to re-establish an RRC connection.

[0088] The operations 800 continue at block 804, where the UE selects a set of values ​​of PRACH parameters to use in the PRACH procedure from the multiple sets of PRACH parameters based on the trigger. Continuing with the above example, the UE 120a selects a set of PRACH parameters to use in the PRACH procedure (e.g., a first set for a higher priority PRACH procedure) from the multiple sets of PRACH parameters (e.g., a first set for a higher priority PRACH procedure and a second set for a lower priority PRACH procedure that the UE received in a SIB sent by the BS) based on the trigger to re-establish the RRC connection.

[0089] Operations 800 continue with the UE performing a PRACH procedure using the selected set of values ​​of the PRACH parameters at block 806. Continuing with the example above, the UE performs a PRACH procedure (e.g., beginning with transmitting a random access preamble as described herein) using the selected set of values ​​of the PRACH parameters (e.g., a first set for a higher priority PRACH procedure).

[0090] According to aspects of the disclosure, a UE may receive one or more sets of values ​​for the PRACH parameters, for example, in a system information block (SIB) transmitted from a base station.

[0091] In aspects of the disclosure, a UE may receive one or more sets of values ​​for the PRACH parameters, for example, via radio resource control (RRC) dedicated signaling transmitted from a base station.

[0092] According to aspects of the disclosure, a UE may receive (e.g., from a base station) an indication that at least one of a data radio bearer (DRB), a quality of service flow indicator data (QFI), or a network slice is associated with a set of values ​​of the PRACH parameters. The network may establish an association of the set of values ​​of the PRACH parameters with one or more DRBs, QFIs, or network slices.

[0093] In an aspect of the present disclosure, the UE may receive an indication (e.g., from a base station) that a set of values ​​of PRACH parameters (e.g., the set of values ​​selected in block 804) is associated with a set of data radio bearers (DRBs), quality of service flow indicators (QFIs), or network slices.

[0094] 9 illustrates example operations 900 for wireless communication that may be performed by a BS (e.g., eNodeB 110a of FIG. 1) in accordance with aspects of the disclosure. The operations 900 may be performed by the BS, for example, to provide a UE with parameters for use by the UE in differentiating the PRACH procedure from other PRACH procedures (e.g., by other UEs or by the UE at another time). The operations 900 may be considered complementary to the operations 800 of FIG. 8 described above.

[0095] The operations 900 begin at block 902, where a BS obtains multiple sets of physical random access channel (PRACH) parameters, each set corresponding to one or more triggers for a PRACH procedure. For example, an eNodeB 110a obtains (e.g., from a configuration file for the eNodeB) multiple sets of PRACH parameters (e.g., a first set for a higher priority PRACH procedure and a second set for a lower priority PRACH procedure), each set corresponding to one or more triggers for a PRACH procedure.

[0096] The operations 900 continue at block 904, where the BS transmits an indication of one of the sets of values ​​of the PRACH parameters and a corresponding trigger for that set. Continuing with the example above, the eNodeB transmits a SIB indicating one of the sets of PRACH parameters (e.g., a first set for a higher priority PRACH procedure) and a corresponding trigger for that set (e.g., that RRC connection re-establishment should occur).

[0097] According to aspects of the present disclosure, the following parameters used in the baseline random access procedure, namely, parameters for preamble transmission including initial received power value (e.g., preambleInitialReceivedTargetPower), power ramping step value (e.g., powerRampingStep), back-off parameter value, and / or back-off multiplier value, can be configured differently for different services / slices / events to achieve differentiation.

[0098] In aspects of the disclosure, if a service, slice, and / or event (e.g., a trigger) requires a faster access to the network by the UE, the UE may use a larger initial received power value (e.g., powerRampingStep) and power ramping step value (powerRampingStep) for the PRACH procedure than the UE and other UEs use for other PRACH procedures. Using a larger value allows the UE to achieve a higher success probability for the PRACH procedure (e.g., a higher success probability for an access request). If an access request is considered to be of lower priority, the UE may use a larger back-off parameter value so that the UE's PRACH procedure is less likely to cause access contention with a higher priority PRACH procedure.

[0099] According to aspects of the present disclosure, if a service is expected to be deployed with many UEs, the UEs may be configured with a small value of the power ramping step value (e.g., powerRampingStep) to avoid excessive interference or contention. Furthermore, a large back-off parameter value may be used by the PRACH procedure by the UEs to reduce their access load on the network.

[0100] In aspects of the present disclosure, if a service and / or slice is sensitive to power consumption, an improved combination of an initial received power value (e.g., preambleInitialReceivedTargetPower) and a power ramping step value (e.g., powerRampingStep) may be configured to minimize the total amount of energy consumed by a UE performing network access. This improved combination may be a trade-off between power and access delay. For example, a lower initial received power value may be used to reduce power consumption. However, the initial received power value should not be too low, since a very low value may reduce access success and possibly result in more retransmissions.

[0101] According to aspects of the present disclosure, when a contention occurs, the network can send back a back-off indicator in a random access response (RAR) message to indicate to the UE how long it should wait before attempting to access the network again (e.g., initiating a new PRACH procedure). The same 4-bit back-off indicator may be sent to all involved UEs, but this indicator can present different tables of back-off values ​​for different services, slices, and / or events, i.e., the same indicator means a shorter back-off duration for higher priority requests than for lower priority requests.

[0102] In aspects of the present disclosure, after the UE receives a backoff indicator in the RAR message, the UE may determine a backoff period based on an initial backoff parameter value and a backoff multiplier. The UE may determine a backoff multiplier based on the priority of the request (e.g., higher or lower) and then determine the backoff period by multiplying the determined backoff multiplier by the initial backoff parameter value. Higher priority access requests may use a smaller backoff multiplier than lower priority access requests.

[0103] In aspects of the present disclosure, to implement the above-mentioned differentiated random access procedures, the network may configure and / or specify (e.g., create and send a configuration to the UE) a mapping between a trigger for a random access request and a set of random access parameters. Such a trigger may include a priority of a logical channel on which data arrival is located, a type of random access event (e.g., resynchronization), or an index into a network slice.

[0104] According to aspects of the present disclosure, a network (e.g., a base station of the network) can provide multiple sets of access parameters in a RACH-related system information block (SIB), and the network can specify which set of parameters an access request should use based on the trigger of the request.

[0105] According to aspects of the disclosure, a network (e.g., a base station of the network) can provide one or more sets of access parameters to a UE via RRC signaling. By providing sets of access parameters to the UE via RRC signaling, the network may be enabled to be more flexible in differentiating connected UEs.

[0106] In aspects of the present disclosure, the mapping between the set of access parameters and the triggers may be specified as part of the Data Radio Bearer (DRB) establishment or as part of the Protocol Data Unit (PDU) session establishment. For example, during the DRB establishment procedure, the UE obtains the set of random access parameters (as previously described) as part of the Quality of Service Flow Indicator (QFI).

[0107] According to aspects of the present disclosure, the priorities of different types of contention-based access events are defined as follows:

[0108] According to aspects of the present disclosure, for initial access by a UE, as well as access triggered by a UE that needs to transmit new data in RRC idle and inactive states (i.e., access control applies), the access priority of a contention-based random access procedure by the UE is based on the access category of the new data that triggered the access procedure.

[0109] In aspects of the present disclosure, the mapping between the access priorities and the above-mentioned access categories may be advertised in system information and / or configured on the UE by the network via dedicated RRC signaling.

[0110] According to aspects of the present disclosure, for an RRC connected UE, for control plane events, handovers using contention based access and RRC connection re-establishment may be assigned a higher access priority, and other control plane events may be assigned a lower access priority.

[0111] In aspects of the present disclosure, for an RRC connected UE, content-based random access events may be assigned a low access priority (e.g., for new data triggered access where SR is assumed to be configured for high access priority traffic).

[0112] According to aspects of the present disclosure, further configuration of access priority may be configured by the network (eg, at the UE) via dedicated RRC signaling.

[0113] Exemplary Configurations of Random Access Windows for Prioritized Random Access As mentioned above, the UE may perform a random access procedure to connect to the network, which includes at least the following steps: 1. The UE transmits a randomly selected preamble sequence (eg, Msg1) at a selected opportunity in the time and frequency domain. 2. After transmitting the preamble, the UE starts a timer (known as the response window) to listen for a reply from the network (known as a Random Access Response, RAR, or Msg2). 3. If the UE successfully receives the RAR before the UE's response window expires (i.e., before the timer expires), the UE proceeds to the second part of the random access procedure (e.g., sends Msg3 of the random access procedure). If the UE does not successfully receive the RAR before the response window expires, the UE retransmits the preamble.

[0114] During this random access procedure, the network generally does not know which UE is transmitting the preamble, so the network must configure RAR windows of the same duration for all UEs. However, it may be desirable for access requests of different types of UEs, or triggered by different types of events (e.g., urgent data vs. delay-tolerant data), to be treated with different priorities. For example, the network may configure response windows of different durations for different types of requests. Configuring response windows of different durations for different types of requests may allow UEs that transmit higher priority access requests to determine faster if the UE needs to retransmit (e.g., higher priority access requests have shorter response windows), and thus allow the UE to have a shorter overall latency in completing the random access procedure.

[0115] According to aspects of the present disclosure, access requests of different priorities may be configured to transmit preamble sequences on different PRACH opportunities in the time and / or frequency domain (e.g., as specified in system information by the BS or other network entity).

[0116] According to aspects of the present disclosure, a network entity (e.g., a BS) may determine a priority of a received preamble sequence based on a set of time and / or frequency resources used in transmitting the preamble sequence, i.e., the BS may receive a preamble sequence within a set of transmission resources and determine a priority of the received preamble sequence (and thus a priority of the RACH procedure being performed by the UE that transmitted the preamble sequence) based on the set of transmission resources.

[0117] According to aspects of the present disclosure, access requests of different priorities (i.e., random access requests as described herein) may be configured (e.g., specified in system information by the BS or other network entity) to use response windows of different durations.

[0118] In an aspect of the present disclosure, a network entity (e.g., a BS) may give a higher priority to a preamble transmitted on a transmission resource for a higher priority PRACH transmission by detecting and processing the preamble and sending a RAR back to the UE transmitting the higher priority PRACH before the response window of the higher priority PRACH expires.

[0119] FIG. 10A is a schematic diagram of a set of transmission resources 1000 reserved (e.g., by a BS for use in a cell served by the BS) for a PRACH signal (e.g., a PRACH region) according to an aspect of the disclosure. The frequency region 1002 is a set of tones to be used by a UE transmitting a higher priority PRACH. For example, a UE may select resources from the frequency region 1002 when transmitting Msg1 of a RACH procedure so that the UE can transmit an Ultra Reliable Low Latency Communication (URLLC) transmission. The frequency region 1004 is a set of tones to be used by a UE transmitting a lower priority PRACH. A cell may select the resources reserved for the PRACH signal from a wider system bandwidth, and the cell may transmit an indication of the resources reserved for the PRACH signal in one or more SIBs and / or via RRC signaling.

[0120] FIG. 10B is a schematic diagram of a set of transmission resources 1050 reserved (e.g., by a BS, by a cell) for a PRACH signal (e.g., a PRACH region) according to an aspect of the disclosure. The time region 1052 is a period to be used by a UE transmitting a higher priority PRACH. For example, a UE may select resources from the time region 1052 when transmitting Msg1 of a RACH procedure so that the UE can transmit an Ultra Reliable Low Latency Communication (URLLC) transmission. The time region 1054 is a period to be used by a UE transmitting a lower priority PRACH. A cell may select resources reserved for a PRACH signal from a wider system bandwidth, and the cell may transmit an indication of the resources reserved for the PRACH signal in one or more SIBs and / or via RRC signaling.

[0121] 10A illustrates a division of PRACH resources in the frequency domain and FIG. 10B illustrates a division of PRACH resources in the time domain, the disclosure is not so limited. PRACH resources may be divided with a combination of time and frequency division. Furthermore, other methods of dividing PRACH resources (e.g., code division) may be used to indicate the priority of the RACH procedure.

[0122] FIG. 11 illustrates example operations 1100 for wireless communication that may be performed by a BS (eg, eNodeB 110a of FIG. 1) in accordance with an aspect of the disclosure.

[0123] The operations 1100 begin at block 1102, where a BS provides an indication of a higher priority PRACH region including a set of transmission resources within a system bandwidth for transmitting a higher priority PRACH signal by a user equipment (UE). For example, an eNodeB 110a provides an indication of a higher priority PRACH region including a set of transmission resources within a system bandwidth for transmitting a higher priority PRACH signal by a UE 120a. The indication may be, for example, a list of frequency resources to be used by the eNodeB to transmit the higher priority PRACH signal in a SIB.

[0124] The operations 1100 continue at block 1104, where the BS determines a response window for the received PRACH signal based on receiving the PRACH signal over the set of transmission resources. Continuing with the example above, the eNodeB determines a response window for the received PRACH signal (e.g., a preamble sequence) based on the eNodeB receiving the PRACH over the set of frequency resources indicated in block 1102.

[0125] 12 illustrates example operations 1200 for wireless communication that may be performed by a UE (e.g., UE 120a of FIG. 1) in accordance with aspects of the present disclosure. The operations 1200 may be considered complementary to the operations 1100 of FIG. 11 described above.

[0126] The operations 1200 begin at block 1202, where a UE obtains an indication of a random access response (RAR) window for a higher priority physical random access channel (PRACH) signal from a base station (BS). For example, the UE 120a may obtain an indication of a RAR window for a higher priority PRACH signal from a SIB transmitted by the eNodeB 110a.

[0127] In block 1204, the UE determines an RAR window for the PRACH signal transmitted to the BS based on the indication that the PRACH signal is a higher priority PRACH signal. Continuing with the example above, the UE 120a determines an RAR window for the PRACH signal (e.g., a random access preamble transmitted by the UE) transmitted to the eNodeB 110a based on the indication that the PRACH signal is a higher priority PRACH signal and the indication (e.g., a SIB) obtained by the UE in block 1202.

[0128] The steps of a method or algorithm described in connection with the present disclosure herein may be embodied directly in hardware, in a software module executed by a processor or processing system, or in a combination thereof. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, PCM (phase change memory), registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from and / or write information to the storage medium. Alternatively, the storage medium may be integral to the processor. The processor, processing system, and / or storage medium may reside in an ASIC. The ASIC may reside in a user terminal. Alternatively, the processor and storage medium may reside in a user terminal as separate components. In general, where there are operations illustrated in figures, those operations may have corresponding equivalent means-plus-function components similarly numbered. For example, the means for determining, the means for executing, the means for transmitting, the means for receiving, the means for sending, the means for applying, the means for providing, the means for selecting, the means for using, the means for updating, the means for obtaining, the means for scheduling, the means for evaluating, and / or the means for measuring may include one or more processors or other elements, such as the transmit processor 264, the controller / processor 280, the receive processor 258, and / or the antennas 252 of the user equipment 120 shown in FIG. 2 and / or the transmit processor 220, the receive processor 238, the controller / processor 240, and / or the antennas 234 of the base station 110 shown in FIG. 2.

[0129] In one or more exemplary designs, the described functions may be implemented in hardware, software, or a combination thereof. If implemented in software, the functions may be stored on or transmitted over a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general purpose or special purpose computer, or a general purpose or special purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, firmware, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0130] Furthermore, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified or clear from the context, for example, the phrase "X employs A or B" is intended to mean any of the natural inclusive permutations. That is, for example, the phrase "X employs A or B" is satisfied by any of the following examples: X employs A, X employs B, or X employs both A and B. References to singular elements as used herein are intended to mean "one or more" and not "one and only" unless expressly stated as such. For example, the articles "a" and "an" as used in this application and the appended claims should be construed generally to mean "one or more" unless otherwise specified or clear from the context that the singular form is intended. Unless otherwise specified, the term "several" refers to one or more. A phrase referring to "at least one of" a list of items refers to any combination of those items, including single members. As an example, "at least one of a, b, or c" is intended to include a, b, c, ab, ac, bc, and abc, as well as any combination having multiple identical elements (e.g., aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc, or any other order of a, b, and c). As used herein, including the claims, the term "and / or," when used in a list of two or more items, means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as including components A, B, and / or C, the composition may include only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C.

[0131] The above description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications of the disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. [Explanation of symbols]

[0132] 100 Wireless Communication Networks 110 BS / eNB 120UE 130 Network Controller 212 Data Source 220 Transmit Processor 230 Transmit (TX) Multiple Input Multiple Output (MIMO) Processor 232 Modulator (MOD) 234 Antenna 236 MIMO Detector 238 Receive Processor 239 Data Sink 240 Controllers / Processors 242 Memory 244 Communication Unit 246 Scheduler 252 Antenna 254 Demodulator (DEMOD) 256 MIMO Detector 258 Receive Processor 260 Data Sink 262 Data Sources 264 Transmit Processor 266 TX MIMO Processor 280 Controller / Processor 282 Memory 290 Controller / Processor 292 Memory 294 Communication Unit

Claims

1. A user equipment (UE) for wireless communications, comprising: Memory, at least one processor coupled to the memory, the at least one processor comprising: receiving a plurality of sets of values ​​of a physical random access channel (PRACH) parameter, the plurality of sets of values ​​of PRACH parameters including a first set of values ​​of PRACH parameters associated with a first event and a second set of values ​​of PRACH parameters associated with a second event different from the first event, the first event including a beam failure event, and the second event including a handover command or availability of data to send; performing a PRACH procedure based on the first event and using the first set of values ​​of PRACH parameters associated with the first event. The UE is configured to:

2. 10. The UE of claim 1, wherein the first set of values ​​for PRACH parameters includes one or more of a back-off multiplier value, an initial received power value, and a power ramping step value.

3. To perform the PRACH procedure, the at least one processor: Transmitting a first random access preamble; receiving a random access response (RAR) in response to the first random access preamble, the RAR including a back-off indicator value; waiting for a period of time determined based on the back-off indicator value and a back-off multiplier value in the first set of values ​​for PRACH parameters; subsequent to waiting the period of time, transmitting a second random access preamble. The UE of claim 2 , configured to:

4. To receive the plurality of sets of values ​​of PRACH parameters, the at least one processor: receiving said sets of values ​​of PRACH parameters in a system information block (SIB); The UE of claim 1 , configured to:

5. the at least one processor: receiving an indication that at least one of a data radio bearer (DRB), a quality of service flow indicator data (QFI), or a network slice is associated with the first set of values ​​of PRACH parameters; The UE of claim 4 , configured to:

6. the at least one processor: receiving an indication that the first set of values ​​of PRACH parameters is associated with a set of Data Radio Bearers (DRBs), Quality of Service Flow Indicators (QFIs), or network slices; The UE of claim 4 , configured to:

7. To receive the plurality of sets of values ​​of PRACH parameters, the at least one processor: receiving said first set of values ​​of PRACH parameters during a Data Radio Bearer (DRB) establishment procedure; The UE of claim 1 , configured to:

8. 8. The UE of claim 7, wherein the multiple sets of values ​​for PRACH parameters are included in a quality of service flow indicator (QFI).

9. the second event includes the handover command; The UE of claim 1.

10. To receive the plurality of sets of values ​​of PRACH parameters, the at least one processor: receiving the plurality of sets of PRACH parameters from a base station (BS), each of the sets of PRACH parameters being associated with at least one of a quality of service flow indicator (QFI), a network slice, a protocol data unit (PDU) session, or a data radio bearer (DRB); The UE of claim 1 , configured to:

11. The second event is Network Slices, Protocol Data Unit (PDU) sessions, Data Radio Bearer (DRB), or Quality of Service Flow Indicator (QFI) The UE of claim 1 , wherein the UE is associated with at least one of:

12. To receive the plurality of sets of values ​​of PRACH parameters, the at least one processor: receiving the plurality of sets of values ​​for PRACH parameters via radio resource control (RRC) dedicated signaling; The UE of claim 1 , configured to:

13. the at least one processor: transmitting an indication that at least one of a data radio bearer (DRB), a quality of service flow indicator data (QFI), or a network slice is associated with the first set of values ​​of PRACH parameters. The UE of claim 12, configured to:

14. the at least one processor: transmitting an indication that the first set of values ​​of PRACH parameters is associated with a set of Data Radio Bearers (DRBs), Quality of Service Flow Indicators (QFIs), or network slices. The UE of claim 12, configured to:

15. A base station (BS) for wireless communications, comprising: Memory, at least one processor coupled to the memory, the at least one processor comprising: obtaining a plurality of sets of values ​​of a physical random access channel (PRACH) parameter, the plurality of sets of values ​​of a PRACH parameter including a first set of values ​​of a PRACH parameter associated with a first event and a second set of values ​​of a PRACH parameter associated with a second event different from the first event, the first event including a beam failure event, and the second event including a handover command or availability of data to send; transmitting data representative of the plurality of sets of PRACH parameter values ​​including the first set of PRACH parameter values ​​and the second set of PRACH parameter values; Configured to do so, BS.

16. 16. The BS of claim 15, wherein the first set of values ​​of PRACH parameters includes one or more of a back-off multiplier value, an initial received power value, and a power ramping step value.

17. to transmit the data representing the plurality of sets of values ​​of PRACH parameters, the at least one processor transmitting said sets of values ​​of PRACH parameters in a system information block (SIB); The BS of claim 15, configured to:

18. to transmit the data representing the plurality of sets of values ​​of PRACH parameters, the at least one processor Transmitting an indication that at least one of a data radio bearer (DRB), a quality of service flow indicator data (QFI), or a network slice is associated with at least one of the plurality of sets of values ​​of PRACH parameters. The BS of claim 17, configured to:

19. to transmit the data representing the plurality of sets of values ​​of PRACH parameters, the at least one processor transmitting an indication that the plurality of sets of values ​​of the PRACH parameters are associated with a set of Data Radio Bearers (DRBs), Quality of Service Flow Indicators (QFIs), or network slices. The BS of claim 17, configured to:

20. to transmit the data representing the plurality of sets of values ​​of PRACH parameters, the at least one processor transmitting said plurality of sets of values ​​of said PRACH parameters during a data radio bearer establishment procedure. The BS of claim 15, configured to:

21. 21. The BS of claim 20, wherein the multiple sets of values ​​of PRACH parameters are included in a Quality of Service Flow Indicator (QFI).

22. the second event includes the handover command; The BS according to claim 15.

23. to transmit the data representing the plurality of sets of values ​​of PRACH parameters, the at least one processor transmitting the data representative of the plurality of sets of PRACH parameters to a user equipment (UE), each of the sets of PRACH parameters being associated with a quality of service flow indicator (QFI); sending to the UE an indication of a network slice to be used in communication with the BS, a network slice including one or more PDU sessions; Each PDU session is associated with one or more QFIs. Each DRB contains one or more QFIs; Each DRB corresponds to the PDU session; The method is configured to: The second event of the random access event is related to setting up a PDU session with the UE and the network slice. The BS according to claim 15.

24. The second event is Network Slices, Protocol Data Unit (PDU) sessions, Data Radio Bearer (DRB), or Quality of Service Flow Indicator (QFI) The BS of claim 15, which is associated with at least one of the following:

25. the at least one processor: Transmitting an indication that at least one of a Data Radio Bearer (DRB), a Quality of Service Flow Indicator Data (QFI), or a network slice is associated with at least one of the first or second set of values ​​of PRACH parameters. The BS of claim 15, configured to:

26. the at least one processor: transmitting an indication that at least one of the sets of values ​​of the PRACH parameters is associated with a set of Data Radio Bearers (DRBs), Quality of Service Flow Indicators (QFIs), or network slices. The BS of claim 15, configured to:

27. A method of wireless communication performed by a base station (BS), comprising: obtaining a plurality of sets of values ​​of a Physical Random Access Channel (PRACH) parameter, the plurality of sets of values ​​of PRACH parameters including a first set of values ​​of PRACH parameters associated with a first event and a second set of values ​​of PRACH parameters associated with a second event different from the first event, the first event being a beam failure event, and the second event including a handover command or availability of data to send; transmitting data representative of the plurality of sets of values ​​of PRACH parameters, the plurality of sets of values ​​of PRACH parameters including the first set of values ​​of PRACH parameters and the second set of values ​​of PRACH parameters; A method comprising:

28. 28. The method of claim 27, wherein the first set of values ​​for PRACH parameters includes one or more of a back-off multiplier value, an initial received power value, and a power ramping step value.

29. 28. The method of claim 27, wherein transmitting the data representing the plurality of sets of values ​​of PRACH parameters comprises transmitting an indication that the plurality of sets of values ​​of PRACH parameters are associated with a set of Data Radio Bearers (DRBs), Quality of Service Flow Indicator data (QFIs), or network slices.

30. the second event includes the handover command; 28. The method of claim 27.

31. 1. A method of wireless communication performed by a user equipment (UE), comprising: receiving a plurality of sets of values ​​of a Physical Random Access Channel (PRACH) parameter, the plurality of sets of values ​​of PRACH parameters including a first set of values ​​of PRACH parameters associated with a first event and a second set of values ​​of PRACH parameters associated with a second event different from the first event, the first event being a beam failure event, and the second event including a handover command or availability of data to send; performing a PRACH procedure based on the first event and using the first set of values ​​of PRACH parameters associated with the first event. A method comprising:

32. the second event includes the handover command; The method of claim 31.

33. the second event includes availability of the data to be sent; The UE of claim 1.

34. the second event includes availability of the data to be sent; The BS according to claim 15.

35. the second event includes availability of the data to be sent; 28. The method of claim 27.

36. the second event includes availability of the data to be sent; The method of claim 31.

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