WO2021203281A1

WO2021203281A1 - Bandwidth selection for communicating random access information

Info

Publication number: WO2021203281A1
Application number: PCT/CN2020/083702
Authority: WO
Inventors: Jing Sun; Xiaoxia Zhang; Changlong Xu; Aleksandar Damnjanovic
Original assignee: Qualcomm Incorporated
Priority date: 2020-04-08
Filing date: 2020-04-08
Publication date: 2021-10-14

Abstract

Bandwidth selection for communication of random access information. A wireless communication device may use one or more resource block (RB) sets for transmitting random access information on a shared radio frequency (RF) spectrum such as an unlicensed band. In some examples, the maximum transmit power for the wireless communication device may be restricted (e.g., by a regulation). Thus, the wireless communication device may, in some circumstances (e.g., when the wireless communication device is at or near a cell edge), transmit the random access information via multiple RB sets instead of a single RB set in an attempt to access a BS. To this end, the BS may allocate multiple RB sets for a random access transmission by the wireless communication device and monitor each of these RB sets for random access information.

Description

BANDWIDTH SELECTION FOR COMMUNICATING RANDOM ACCESS INFORMATION

INTRODUCTION

The technology discussed below relates generally to wireless communication, and more particularly but not exclusively, to techniques for selecting bandwidth for communication of random access information.

Next-generation wireless communication systems (e.g., 5GS) may include a 5G core network and a 5G radio access network (RAN) , such as a New Radio (NR) -RAN. The NR-RAN supports communication via one or more cells. For example, a wireless communication device such as a user equipment (UE) may access a first cell of a first base station (BS) such as a gNB and/or access a second cell of a second BS.

A BS may schedule access to a cell to support access by multiple UEs. For example, a BS may allocate different resources (e.g., time domain and frequency domain resources) for different UEs operating within a cell of the BS.

As the demand for mobile broadband access continues to increase, research and development continue to advance communication technologies, including technologies for enhancing communication within a wireless network in particular, not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

BRIEF SUMMARY OF SOME EXAMPLES

The following presents a summary of one or more aspects of the present disclosure, in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a form as a prelude to the more detailed description that is presented later.

Various aspects of the disclosure relate to bandwidth selection for communication of random access information (e.g., a physical random access channel, PRACH) . A wireless communication device may use one or more resource block (RB) sets for transmitting random access information on a shared radiofrequency (RF) spectrum such as an unlicensed band. In some examples, the maximum transmit power for the wireless communication device may be restricted (e.g., by a regulation) . Thus, the wireless communication device may, in some circumstances (e.g., when the wireless communication device is at or near a cell edge) , transmit the random access information via multiple RB sets instead of a single RB set in an attempt to access a BS. To this end, the BS may allocate multiple RB sets for a random access transmission by the wireless communication device and monitor each of these RB sets for random access information.

In some examples, a method of communication at a wireless communication device may include identifying a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, selecting at least one RB set of the plurality of RB sets, and sending at least one PRACH sequence on the at least one RB set.

In some examples, a wireless communication device may include a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory. The processor and the memory may be configured to identify a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, select at least one RB set of the plurality of RB sets, and send via the transceiver at least one PRACH sequence on the at least one RB set.

In some examples, a wireless communication device may include means for identifying a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, means for selecting at least one RB set of the plurality of RB sets, and means for sending at least one PRACH sequence on the at least one RB set.

In some examples, an article of manufacture for use by a wireless communication device includes a computer-readable medium having stored therein instructions executable by one or more processors of the wireless communication device to identify a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, select at least one RB set of the plurality of RB sets, and send at least one PRACH sequence on the at least one RB set.

In some examples, a method of communication at a base station may include generating a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, sending the configuration to a wireless communication device, and receiving at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.

In some examples, a base station may include a transceiver, a memory, and a processor communicatively coupled to the transceiver and the memory. The processor and the memory may be configured to generate a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, send the configuration to a wireless communication device via the transceiver, and receive, via the transceiver, at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.

In some examples, a base station may include means for generating a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, means for sending the configuration to a wireless communication device, and means for receiving at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.

In some examples, an article of manufacture for use by a base station includes a computer-readable medium having stored therein instructions executable by one or more processors of the base station to generate a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum, send the configuration to a wireless communication device, and receive at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.

These and other aspects of the disclosure will become more fully understood upon a review of the detailed description, which follows. Other aspects, features, and embodiments of the present disclosure will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, example embodiments of the present disclosure in conjunction with the accompanying figures. While features of the present disclosure may be discussed relative to certain embodiments and figures below, all embodiments of the present disclosure can include one or more of the advantageous features discussed herein. In other words, while one or more embodiments may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various embodiments of the disclosure discussed herein. In similar fashion, while example embodiments may be discussed below as device, system, or method embodiments it should be understood that such example embodiments can be implemented in various devices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a wireless communication system according to some aspects of the disclosure.

FIG. 2 is a conceptual illustration of an example of a radio access network according to some aspects of the disclosure.

FIG. 3 is a schematic illustration of wireless resources in an air interface utilizing orthogonal frequency divisional multiplexing (OFDM) according to some aspects of the disclosure.

FIG. 4 is a conceptual illustration of an example of resources on an uplink interlace according to some aspects of the disclosure.

FIG. 5 is a conceptual illustration of an example of random access information sent via multiple RB sets according to some aspects of the disclosure.

FIG. 6 is a conceptual illustration of an example of a power ramping process according to some aspects of the disclosure.

FIG. 7 is a conceptual illustration of examples of random access channel (RACH) occasions (ROs) for different RB sets according to some aspects of the disclosure.

FIG. 8 is a signaling diagram illustrating an example of sub-band transmission according to some aspects of the disclosure.

FIG. 9 is a block diagram conceptually illustrating an example of a hardware implementation for a communication device employing a processing system according to some aspects of the disclosure.

FIG. 10 is a flow chart illustrating an example wireless communication process according to some aspects of the disclosure.

FIG. 11 is a block diagram conceptually illustrating an example of a hardware implementation for a communication device employing a processing system according to some aspects of the disclosure.

FIG. 12 is a flow chart illustrating an example wireless communication process according to some aspects of the disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

While aspects and embodiments are described in this application by illustration to some examples, those skilled in the art will understand that additional implementations and use cases may come about in many different arrangements and scenarios. Innovations described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, packaging arrangements. For example, embodiments and/or uses may come about via integrated chip embodiments and other non-module-component based devices (e.g., end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, AI-enabled devices, etc. ) . While some examples may or may not be specifically directed to use cases or applications, a wide assortment of applicability of described innovations may occur. Implementations may range a spectrum from chip-level or modular components to non-modular, non-chip-level implementations and further to aggregate, distributed, or OEM devices or systems incorporating one or more aspects of the described innovations. In some practical settings, devices incorporating described aspects and features may also necessarily include additional components and features for implementation and practice of claimed and described embodiments. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes (e.g., hardware components including antenna, RF-chains, power amplifiers, modulators, buffer, processor (s) , interleaver, adders/summers, etc. ) . It is intended that innovations described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, end-user devices, etc. of varying sizes, shapes and constitution.

I. WIRELESS COMMUNICATION PLATFORM

The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. Referring now to FIG. 1, as an illustrative example without limitation, various aspects of the present disclosure are illustrated with reference to a wireless communication system 100. The wireless communication system 100 includes three interacting domains: a core network 102, a radio access network (RAN) 104, and at least one scheduled entity 106. The at least one scheduled entity 106 may be referred to as a user equipment (UE) 106 in the discussion that follows. The RAN 104 includes at least one scheduling entity 108. The at least one scheduling entity 108 may be referred to as a base station (BS) 108 in the discussion that follows. By virtue of the wireless communication system 100, the UE 106 may be enabled to carry out data communication with an external data network 110, such as (but not limited to) the Internet.

The RAN 104 may implement any suitable wireless communication technology or technologies to provide radio access to the UE 106. As one example, the RAN 104 may operate according to 3rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as 5G. As another example, the RAN 104 may operate under a hybrid of 5G NR and Evolved Universal Terrestrial Radio Access Network (eUTRAN) standards, often referred to as LTE. The 3GPP refers to this hybrid RAN as a next-generation RAN, or NG-RAN. Of course, many other examples may be utilized within the scope of the present disclosure.

As illustrated, the RAN 104 includes a plurality of base stations 108. Broadly, a base station is a network element in a radio access network responsible for radio transmission and reception in one or more cells to or from a UE. In different technologies, standards, or contexts, a base station may variously be referred to by those skilled in the art as a base transceiver station (BTS) , a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS) , an extended service set (ESS) , an access point (AP) , a Node B (NB) , an eNode B (eNB) , a gNode B (gNB) , or some other suitable terminology.

The radio access network 104 is further illustrated supporting wireless communication for multiple mobile apparatuses. A mobile apparatus may be referred to as user equipment (UE) in 3GPP standards, but may also be referred to by those skilled in the art as a mobile station (MS) , a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT) , a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. A UE may be an apparatus that provides a user with access to network services.

Within the present document, a “mobile” apparatus need not necessarily have a capability to move, and may be stationary. The term mobile apparatus or mobile device broadly refers to a diverse array of devices and technologies. UEs may include a number of hardware structural components sized, shaped, and arranged to help in communication; such components can include antennas, antenna arrays, RF chains, amplifiers, one or more processors, etc. electrically coupled to each other. For example, some non-limiting examples of a mobile apparatus include a mobile, a cellular (cell) phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal computer (PC) , a notebook, a netbook, a smartbook, a tablet, a personal digital assistant (PDA) , and a broad array of embedded systems, e.g., corresponding to an “Internet of Things” (IoT) . A mobile apparatus may additionally be an automotive or other transportation vehicle, a remote sensor or actuator, a robot or robotics device, a satellite radio, a global positioning system (GPS) device, an object tracking device, a drone, a multi-copter, a quad-copter, a remote control device, a consumer and/or wearable device, such as eyewear, a wearable camera, a virtual reality device, a smart watch, a health or fitness tracker, a digital audio player (e.g., MP3 player) , a camera, a game console, etc. A mobile apparatus may additionally be a digital home or smart home device such as a home audio, video, and/or multimedia device, an appliance, a vending machine, intelligent lighting, a home security system, a smart meter, etc. A mobile apparatus may additionally be a smart energy device, a security device, a solar panel or solar array, a municipal infrastructure device controlling electric power (e.g., a smart grid) , lighting, water, etc.; an industrial automation and enterprise device; a logistics controller; agricultural equipment; military defense equipment, vehicles, aircraft, ships, and weaponry, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, i.e., health care at a distance. Telehealth devices may include telehealth monitoring devices and telehealth administration devices, whose communication may be given preferential treatment or prioritized access over other types of information, e.g., in terms of prioritized access for transport of critical service data, and/or relevant QoS for transport of critical service data.

Wireless communication between a RAN 104 and a UE 106 may be described as utilizing an air interface. Transmissions over the air interface from a base station (e.g., base station 108) to one or more UEs (e.g., UE 106) may be referred to as downlink (DL) transmission. In accordance with certain aspects of the present disclosure, the term downlink may refer to a point-to-multipoint transmission originating at a scheduling entity (described further below; e.g., base station 108) . Another way to describe this scheme may be to use the term broadcast channel multiplexing. Transmissions from a UE (e.g., UE 106) to a base station (e.g., base station 108) may be referred to as uplink (UL) transmissions. In accordance with further aspects of the present disclosure, the term uplink may refer to a point-to-point transmission originating at a scheduled entity (described further below; e.g., UE 106) .

In some examples, access to the air interface may be scheduled, wherein a scheduling entity (e.g., a base station 108) allocates resources for communication among some or all devices and equipment within its service area or cell. Within the present disclosure, as discussed further below, the scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more scheduled entities. That is, for scheduled communication, UEs 106, which may be scheduled entities, may utilize resources allocated by the scheduling entity 108.

Base stations 108 are not the only entities that may function as scheduling entities. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more scheduled entities (e.g., one or more other UEs) .

As illustrated in FIG. 1, a scheduling entity 108 may broadcast downlink traffic 112 to one or more scheduled entities 106. Broadly, the scheduling entity 108 is a node or device responsible for scheduling traffic in a wireless communication network, including the downlink traffic 112 and, in some examples, uplink traffic 116 from one or more scheduled entities 106 to the scheduling entity 108. On the other hand, the scheduled entity 106 is a node or device that receives downlink control information 114, including but not limited to scheduling information (e.g., a grant) , synchronization or timing information, or other control information from another entity in the wireless communication network such as the scheduling entity 108.

In addition, the uplink and/or downlink control information and/or traffic information may be time-divided into frames, subframes, slots, and/or symbols. As used herein, a symbol may refer to a unit of time that, in an orthogonal frequency division multiplexed (OFDM) waveform, carries one resource element (RE) per sub-carrier. A slot may carry 7 or 14 OFDM symbols. A subframe may refer to a duration of 1ms. Multiple subframes or slots may be grouped together to form a single frame or radio frame. Of course, these definitions are not required, and any suitable scheme for organizing waveforms may be utilized, and various time divisions of the waveform may have any suitable duration.

In general, base stations 108 may include a backhaul interface for communication with a backhaul portion 120 of the wireless communication system. The backhaul 120 may provide a link between a base station 108 and the core network 102. Further, in some examples, a backhaul network may provide interconnection between the respective base stations 108. Various types of backhaul interfaces may be employed, such as a direct physical connection, a virtual network, or the like using any suitable transport network.

The core network 102 may be a part of the wireless communication system 100, and may be independent of the radio access technology used in the RAN 104. In some examples, the core network 102 may be configured according to 5G standards (e.g., 5GC) . In other examples, the core network 102 may be configured according to a 4G evolved packet core (EPC) , or any other suitable standard or configuration.

Referring now to FIG. 2, by way of example and without limitation, a schematic illustration of a RAN 200 is provided. In some examples, the RAN 200 may be the same as the RAN 104 described above and illustrated in FIG. 1. The geographic area covered by the RAN 200 may be divided into cellular regions (cells) that can be uniquely identified by a user equipment (UE) based on an identification broadcasted from one access point or base station. FIG. 2 illustrates

macrocells

202, 204, and 206, and a small cell 208, each of which may include one or more sectors (not shown) . A sector is a sub-area of a cell. All sectors within one cell are served by the same base station. A radio link within a sector can be identified by a single logical identification belonging to that sector. In a cell that is divided into sectors, the multiple sectors within a cell can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell.

Various base station arrangements can be utilized. For example, in FIG. 2, two base stations 210 and 212 are shown in

cells

202 and 204; and a third base station 214 is shown controlling a remote radio head (RRH) 216 in cell 206. That is, a base station can have an integrated antenna or can be connected to an antenna or RRH by feeder cables. In the illustrated example, the

cells

202, 204, and 206 may be referred to as macrocells, as the

base stations

210, 212, and 214 support cells having a large size. Further, a base station 218 is shown in the small cell 208 (e.g., a microcell, picocell, femtocell, home base station, home Node B, home eNode B, etc. ) which may overlap with one or more macrocells. In this example, the cell 208 may be referred to as a small cell, as the base station 218 supports a cell having a relatively small size. Cell sizing can be done according to system design as well as component constraints.

It is to be understood that the radio access network 200 may include any number of wireless base stations and cells. Further, a relay node may be deployed to extend the size or coverage area of a given cell. The

base stations

210, 212, 214, 218 provide wireless access points to a core network for any number of mobile apparatuses. In some examples, the

base stations

210, 212, 214, and/or 218 may be the same as the base station/scheduling entity 108 described above and illustrated in FIG. 1.

Within the RAN 200, the cells may include UEs that may be in communication with one or more sectors of each cell. Further, each

base station

210, 212, 214, and 218 may be configured to provide an access point to a core network (e.g., as illustrated in FIG. 1) for all the UEs in the respective cells. For example, UEs 222 and 224 may be in communication with base station 210;

UEs

226 and 228 may be in communication with base station 212;

UEs

230 and 232 may be in communication with base station 214 by way of RRH 216; and UE 234 may be in communication with base station 218. In some examples, the

UEs

222, 224, 226, 228, 230, 232, 234, 238, 240, and/or 242 may be the same as the UE/scheduled entity 106 described above and illustrated in FIG. 1.

In some examples, an unmanned aerial vehicle (UAV) 220, which may be a drone or quadcopter, can be a mobile network node and may be configured to function as a UE. For example, the UAV 220 may operate within cell 202 by communicating with base station 210.

In a further aspect of the RAN 200, sidelink signals may be used between UEs without necessarily relying on scheduling or control information from a base station. For example, two or more UEs (e.g., UEs 226 and 228) may communicate with each other using peer to peer (P2P) or sidelink signals 227 without relaying that communication through a base station (e.g., base station 212) . In a further example, UE 238 is illustrated communicating with

UEs

240 and 242. Here, the UE 238 may function as a scheduling entity or a primary sidelink device, and

UEs

240 and 242 may function as a scheduled entity or a non-primary (e.g., secondary) sidelink device. In still another example, a UE may function as a scheduling entity in a device-to-device (D2D) , peer- to-peer (P2P) , or vehicle-to-vehicle (V2V) network, and/or in a mesh network. In a mesh network example,

UEs

240 and 242 may optionally communicate directly with one another in addition to communicating with the UE 238 (e.g., functioning as a scheduling entity) . Thus, in a wireless communication system with scheduled access to time–frequency resources and having a cellular configuration, a P2P configuration, or a mesh configuration, a scheduling entity and one or more scheduled entities may communicate utilizing the scheduled resources. In some examples, the sidelink signals 227 include sidelink traffic (e.g., a physical sidelink shared channel) and sidelink control (e.g., a physical sidelink control channel) .

In the radio access network 200, the ability for a UE to communicate while moving, independent of its location, is referred to as mobility. The various physical channels between the UE and the radio access network are generally set up, maintained, and released under the control of an access and mobility management function (AMF) . The AMF (not shown in FIG. 2) may include a security context management function (SCMF) that manages the security context for both the control plane and the user plane functionality, and a security anchor function (SEAF) that performs authentication.

A radio access network 200 may utilize DL-based mobility or UL-based mobility to enable mobility and handovers (i.e., the transfer of a UE’s connection from one radio channel to another) . In a network configured for DL-based mobility, during a call with a scheduling entity, or at any other time, a UE may monitor various parameters of the signal from its serving cell as well as various parameters of neighboring cells. Depending on the quality of these parameters, the UE may maintain communication with one or more of the neighboring cells. During this time, if the UE moves from one cell to another, or if signal quality from a neighboring cell exceeds that from the serving cell for a given amount of time, the UE may undertake a handoff or handover from the serving cell to the neighboring (target) cell. For example, UE 224 (illustrated as a vehicle, although any suitable form of UE may be used) may move from the geographic area corresponding to its serving cell 202 to the geographic area corresponding to a neighbor cell 206. When the signal strength or quality from the neighbor cell 206 exceeds that of its serving cell 202 for a given amount of time, the UE 224 may transmit a reporting message to its serving base station 210 indicating this condition. In response, the UE 224 may receive a handover command, and the UE may undergo a handover to the cell 206.

In a network configured for UL-based mobility, UL reference signals from each UE may be utilized by the network to select a serving cell for each UE. In some examples, the

base stations

210, 212, and 214/216 may broadcast unified synchronization signals (e.g., unified Primary Synchronization Signals (PSSs) , unified Secondary Synchronization Signals (SSSs) and unified Physical Broadcast Channels (PBCH) ) . The

UEs

222, 224, 226, 228, 230, and 232 may receive the unified synchronization signals, derive the carrier frequency and slot timing from the synchronization signals, and in response to deriving timing, transmit an uplink pilot or reference signal. The uplink pilot signal transmitted by a UE (e.g., UE 224) may be concurrently received by two or more cells (e.g., base stations 210 and 214/216) within the radio access network 200. Each of the cells may measure a strength of the pilot signal, and the radio access network (e.g., one or more of the base stations 210 and 214/216 and/or a central node within the core network) may determine a serving cell for the UE 224. As the UE 224 moves through the radio access network 200, the network may continue to monitor the uplink pilot signal transmitted by the UE 224. When the signal strength or quality of the pilot signal measured by a neighboring cell exceeds that of the signal strength or quality measured by the serving cell, the network 200 may handover the UE 224 from the serving cell to the neighboring cell, with or without informing the UE 224.

Although the synchronization signal transmitted by the

base stations

210, 212, and 214/216 may be unified, the synchronization signal may not identify a particular cell, but rather may identify a zone of multiple cells operating on the same frequency and/or with the same timing. The use of zones in 5G networks or other next generation communication networks enables the uplink-based mobility framework and improves the efficiency of both the UE and the network, since the number of mobility messages that need to be exchanged between the UE and the network may be reduced.

A UE may use a random access procedure for initial access to a RAN (e.g., the RAN 200 of FIG. 2) . The RAN (e.g., a base station) broadcasts information that enables a UE to determine how to conduct the initial access. This information may include a configuration for a physical random access channel (PRACH) that the UE uses to communicate with the RAN during initial access. The PRACH configuration may indicate, for example, the resources (e.g., RACH occasions (ROs) ) allocated by the RAN for the PRACH. For example, an RO may be a sets of symbols (e.g., in a PRACH slot) that are scheduled by a BS for sending the PRACH. On some aspects, bundled ROs may refer to a set of ROs scheduled by a BS for sending the PRACH.

In various implementations, the air interface in the radio access network 200 may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. Licensed spectrum provides for exclusive use of a portion of the spectrum, generally by virtue of a mobile network operator purchasing a license from a government regulatory body. Unlicensed spectrum provides for shared use of a portion of the spectrum without need for a government-granted license. While compliance with some technical rules is generally still required to access unlicensed spectrum, generally, any operator or device may gain access. Shared spectrum may fall between licensed and unlicensed spectrum, wherein technical rules or limitations may be required to access the spectrum, but the spectrum may still be shared by multiple operators and/or multiple RATs. For example, the holder of a license for a portion of licensed spectrum may provide licensed shared access (LSA) to share that spectrum with other parties, e.g., with suitable licensee-determined conditions to gain access.

The air interface in the radio access network 200 may utilize one or more multiplexing and multiple access algorithms to enable simultaneous communication of the various devices. For example, 5G NR specifications provide multiple access for UL transmissions from UEs 222 and 224 to base station 210, and for multiplexing for DL transmissions from base station 210 to one or more UEs 222 and 224, utilizing orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) . In addition, for UL transmissions, 5G NR specifications provide support for discrete Fourier transform-spread-OFDM (DFT-s-OFDM) with a CP (also referred to as single-carrier FDMA (SC-FDMA) ) . However, within the scope of the present disclosure, multiplexing and multiple access are not limited to the above schemes, and may be provided utilizing time division multiple access (TDMA) , code division multiple access (CDMA) , frequency division multiple access (FDMA) , sparse code multiple access (SCMA) , resource spread multiple access (RSMA) , or other suitable multiple access schemes. Further, multiplexing DL transmissions from the base station 210 to UEs 222 and 224 may be provided utilizing time division multiplexing (TDM) , code division multiplexing (CDM) , frequency division multiplexing (FDM) , orthogonal frequency division multiplexing (OFDM) , sparse code multiplexing (SCM) , or other suitable multiplexing schemes.

The air interface in the radio access network 200 may further utilize one or more duplexing algorithms. Duplex refers to a point-to-point communication link where both endpoints can communicate with one another in both directions. Full duplex means both endpoints can simultaneously communicate with one another. Half duplex means only one endpoint can send information to the other at a time. In a wireless link, a full duplex channel generally relies on physical isolation of a transmitter and receiver, and suitable interference cancelation technologies. Full duplex emulation is frequently implemented for wireless links by utilizing frequency division duplex (FDD) or time division duplex (TDD) . In FDD, transmissions in different directions operate at different carrier frequencies. In TDD, transmissions in different directions on a given channel are separated from one another using time division multiplexing. That is, at some times the channel is dedicated for transmissions in one direction, while at other times the channel is dedicated for transmissions in the other direction, where the direction may change very rapidly, e.g., several times per slot.

Various aspects of the present disclosure will be described with reference to an OFDM waveform, an example of which is schematically illustrated in FIG. 3. It should be understood by those of ordinary skill in the art that the various aspects of the present disclosure may be applied to an SC-FDMA waveform in substantially the same way as described herein below. That is, while some examples of the present disclosure may focus on an OFDM link for clarity, it should be understood that the same principles may be applied as well to SC-FDMA waveforms.

Referring now to FIG. 3, an expanded view of an example DL subframe (SF) 302A is illustrated, showing an OFDM resource grid. However, as those skilled in the art will readily appreciate, the PHY transmission structure for any particular application may vary from the example described here, depending on any number of factors. Here, time is in the horizontal direction with units of OFDM symbols; and frequency is in the vertical direction with units of subcarriers.

The resource grid 304 may be used to schematically represent time–frequency resources for a given antenna port. That is, in a multiple-input-multiple-output (MIMO) implementation with multiple antenna ports available, a corresponding multiple number of resource grids 304 may be available for communication. The resource grid 304 is divided into multiple resource elements (REs) 306. An RE, which is 1 subcarrier × 1 symbol, is the smallest discrete part of the time–frequency grid, and contains a single complex value representing data from a physical channel or signal. Depending on the modulation utilized in a particular implementation, each RE may represent one or more bits of information. In some examples, a block of REs may be referred to as a physical resource block (PRB) or more simply a resource block (RB) 308, which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include 12 subcarriers, a number independent of the numerology used. In some examples, depending on the numerology, an RB may include any suitable number of consecutive OFDM symbols in the time domain. Within the present disclosure, it is assumed that a single RB such as the RB 308 entirely corresponds to a single direction of communication (either transmission or reception for a given device) .

Scheduling of UEs (e.g., scheduled entities) for downlink or uplink transmissions typically involves scheduling one or more resource elements 306 within one or more bandwidth parts (BWPs) , where each BWP includes two or more contiguous or consecutive RBs. Thus, a UE generally utilizes only a subset of the resource grid 304. In some examples, an RB may be the smallest unit of resources that can be allocated to a UE. Thus, the more RBs scheduled for a UE, and the higher the modulation scheme chosen for the air interface, the higher the data rate for the UE.

In this illustration, the RB 308 is shown as occupying less than the entire bandwidth of the subframe 302A, with some subcarriers illustrated above and below the RB 308. In a given implementation, the subframe 302A may have a bandwidth corresponding to any number of one or more RBs 308. Further, in this illustration, the RB 308 is shown as occupying less than the entire duration of the subframe 302A, although this is merely one possible example.

Each 1 ms subframe 302A may consist of one or multiple adjacent slots. In the example shown in FIG. 3, one subframe 302B includes four slots 310, as an illustrative example. In some examples, a slot may be defined according to a specified number of OFDM symbols with a given cyclic prefix (CP) length. For example, a slot may include 7 or 14 OFDM symbols with a nominal CP. Additional examples may include mini-slots having a shorter duration (e.g., one or two OFDM symbols) . These mini-slots may in some cases be transmitted occupying resources scheduled for ongoing slot transmissions for the same or for different UEs.

An expanded view of one of the slots 310 illustrates the slot 310 including a control region 312 and a data region 314. In general, the control region 312 may carry control channels (e.g., PDCCH) , and the data region 314 may carry data channels (e.g., PDSCH or PUSCH) . Of course, a slot may contain all DL, all UL, or at least one DL portion and at least one UL portion. The simple structure illustrated in FIG. 3 is merely exemplary in nature, and different slot structures may be utilized, and may include one or more of each of the control region (s) and data region (s) .

Although not illustrated in FIG. 3, the various REs 306 within a RB 308 may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs 306 within the RB 308 may also carry pilots or reference signals, including but not limited to a demodulation reference signal (DMRS) or a sounding reference signal (SRS) . These pilots or reference signals may provide for a receiving device to perform channel estimation of the corresponding channel, which may enable coherent demodulation/detection of the control and/or data channels within the RB 308.

In a DL transmission, the transmitting device (e.g., the scheduling entity) may allocate one or more REs 306 (e.g., within a control region 312) to carry DL control information including one or more DL control channels, such as a PBCH; a physical control format indicator channel (PCFICH) ; a physical hybrid automatic repeat request (HARQ) indicator channel (PHICH) ; and/or a physical downlink control channel (PDCCH) , etc., to one or more scheduled entities. The transmitting device may further allocate one or more REs 306 to carry other DL signals, such as a DMRS; a phase-tracking reference signal (PT-RS) ; a channel state information –reference signal (CSI-RS) ; a primary synchronization signal (PSS) ; and a secondary synchronization signal (SSS) .

The synchronization signals PSS and SSS, and in some examples, the PBCH and a PBCH DMRS, may be transmitted in a synchronization signal block (SSB) that includes 3 consecutive OFDM symbols, numbered via a time index in increasing order from 0 to 3. In the frequency domain, the SSB may extend over 240 contiguous subcarriers, with the subcarriers being numbered via a frequency index in increasing order from 0 to 239. Of course, the present disclosure is not limited to this specific SSB configuration. Other nonlimiting examples may utilize greater or fewer than two synchronization signals; may include one or more supplemental channels in addition to the PBCH; may omit a PBCH; and/or may utilize a different number of symbols and/or nonconsecutive symbols for an SSB, within the scope of the present disclosure.

The SSB may be used to send system information (SI) and/or provide a reference to SI transmitted via another channel. Examples of system information may include, but are not limited to, subcarrier spacing, system frame number, a cell global identifier (CGI) , a cell bar indication, a list of common control resource sets (coresets) , a list of common search spaces, a search space for SIB1, a paging search space, a random access search space, and uplink configuration information. Two specific examples of coresets include PDCCH Coreset 0 and Coreset 1.

The SI may be subdivided into three sets referred to as minimum SI (MSI) , remaining MSI (RMSI) , and other SI (OSI) . The PBCH may carry the MSI and some of the RMSI. For example, the PBCH may carry a master information block (MIB) that includes various types of system information, along with parameters for decoding a system information block (SIB) .

The RMSI may include, for example, a SystemInformationType1 (SIB1) that contains various additional system information. The RMSI may be carried by a PDSCH (e.g., at a dedicated Coreset 0) .

The PCFICH provides information to assist a receiving device in receiving and decoding the PDCCH. The PDCCH carries downlink control information (DCI) including but not limited to power control commands, scheduling information, a grant, and/or an assignment of REs for DL and UL transmissions. The PHICH carries HARQ feedback transmissions such as an acknowledgment (ACK) or negative acknowledgment (NACK) . HARQ is a technique well-known to those of ordinary skill in the art, wherein the integrity of packet transmissions may be checked at the receiving side for accuracy, e.g., utilizing any suitable integrity checking mechanism, such as a checksum or a cyclic redundancy check (CRC) . If the integrity of the transmission confirmed, an ACK may be transmitted, whereas if not confirmed, a NACK may be transmitted. In response to a NACK, the transmitting device may send a HARQ retransmission, which may implement chase combining, incremental redundancy, etc.

In an UL transmission, the transmitting device (e.g., the scheduled entity) may utilize one or more REs 306 to carry UL control information including one or more UL control channels, such as a physical uplink control channel (PUCCH) , to the scheduling entity. UL control information may include a variety of packet types and categories, including pilots, reference signals, and information configured to enable or assist in decoding uplink data transmissions. For example, the UL control information may include a DMRS or SRS. In some examples, the control information may include a scheduling request (SR) , i.e., request for the scheduling entity to schedule uplink transmissions. Here, in response to the SR transmitted on the control channel, the scheduling entity may transmit downlink control information that may schedule resources for uplink packet transmissions. UL control information may also include HARQ feedback, channel state feedback (CSF) , or any other suitable UL control information.

In addition to control information, one or more REs 306 (e.g., within the data region 314) may be allocated for user data or traffic data. Such traffic may be carried on one or more traffic channels, such as, for a DL transmission, a PDSCH; or for an UL transmission, a physical uplink shared channel (PUSCH) . In some examples, one or more REs 306 within the data region 314 may be configured to carry SIBs (e.g., SIB1) , carrying system information that may enable access to a given cell.

These physical channels described above are generally multiplexed and mapped to transport channels for handling at the medium access control (MAC) layer. Transport channels carry blocks of information called transport blocks (TB) . The transport block size (TBS) , which may correspond to a number of bits of information, may be a controlled parameter, based on the modulation and coding scheme (MCS) and the number of RBs in a given transmission.

The channels or carriers described above with reference to FIGs. 1 -3 are not necessarily all of the channels or carriers that may be utilized between a scheduling entity and scheduled entities, and those of ordinary skill in the art will recognize that other channels or carriers may be utilized in addition to those illustrated, such as other traffic, control, and feedback channels.

II. EXAMPLES FOR BANDWIDTH SELECTION FOR

COMMUNICATING RANDOM ACCESS INFORMATION

As discussed above, a network may use unlicensed radio frequency (RF) spectrum in some scenarios. For example, a network operator may deploy cells that are configured to communicate on an unlicensed RF spectrum (e.g., in addition to cells operating on a licensed RF spectrum) to extend the coverage of the network or to provide additional services (e.g., higher throughput) to UEs operating within the network.

In some scenarios, devices that transmit over unlicensed RF spectrum may use a collision avoidance scheme to reduce the possibility that multiple devices will transmit on the same band at the same time. One example of such a collision avoidance scheme is a listen-before-talk (LBT) procedure. In general, before a first device transmits on a resource, the first device may listen for transmissions by another device. If the resource is currently being used, the first device may back-off for a period of time and then re-attempt transmission (e.g., by listening for other transmissions again) . The first device could also select a different resource in the unlicensed band. If the resource is free, the first device may reserve the resource for a subsequent communication. Carrier sense multiple access (CSMA) is one example of an LBT procedure. Other types of LBT procedures may be used as well.

NR operation in the unlicensed RF spectrum may be referred to as NR-U. Under NR-U, some transmissions may be subject to LBT. Thus, a wireless device such as a UE or an eNB may perform a clear channel assessment (CCA) prior to gaining control of a wireless channel in an unlicensed band. For example, under NR-U, a gNB’s scheduling of uplink and downlink transmissions may be subject to LBT.

A BS may schedule uplink transmissions for UEs, specifying which time-domain and frequency-domain resources each UE is to use for its respective uplink transmission. For UL transmissions on an unlicensed RF spectrum, interlaced-based scheduling may be used in the frequency domain. For example, in NR-U, a PRB interlaced waveform may be used in the UL to satisfy occupied channel bandwidth (OCB) goals and/or to boost UL transmit power for a given power spectral density (PSD) limitation.

A BS may schedule a UE to transmit according to one of more of the interlaces. For example, a BS may schedule a first UE to transmit on interlace 0 and schedule a second UE to transmit on interlace 1. As another example, a BS may schedule a first UE to transmit on interlace 0 and interlace 1. Other examples are possible.

FIG. 4 illustrates an example of an UL interlace 400 (e.g., for NR-U) . A given interlace may correspond to a set of frequency resources. For example, each block (e.g., block 402) in FIG. 4 may correspond to a resource block. FIG. 4 also illustrates that different sets of RBs (e.g., RB set 0 and RB set 1, etc. ) may be defined with respect to an interlace. Here, each RB set includes ten RBs of the interlace. A different number of RBs per RB set may be used in other examples.

Wireless communication operations in certain frequency bands may be subject to regulatory restrictions (e.g., FCC regulation) . For example, Table 1 describes an example of a 6 GHz band. This band is currently used, for example, for microwave communication, backhaul communication, and video camera communication.

BAND	FROM (MHz)	To (MHz)	BANDWIDTH (MHz)
U-NII-5	5925	6425	500
U-NII-6	6425	6525	100
U-NII-7	6525	6875	350
U-NII-8	6875	7125	250

TABLE 1

Devices communicating on the 6 GHz band might not use spectrum sharing techniques. Consequently, maximum transmit power on this band may be limited to, for example, 5 decibel-milliwatts/MHz (dBm/MHz) for a gNB and -1 dBm/MHz for a UE. This is to protect incumbent users of this band (e.g., video cameras) .

In the above examples, use of the 6 GHz band (e.g., U-NII-5 and U-NII-7) may be subject to a transmit power limit that is lower than the transmit power limit imposed on other bands. For example, maximum transmit power on a 5 GHz band may be limited to, for example, 10 dBm/MHz for a gNB and 10 dBm/MHz for a UE.

Given that the power spectral density (PSD) limitation on the 6 GHz band is substantially lower than on the 5GHz band, the total transmit power allowed may be limited by bandwidth occupied. Moreover, in 3GPP Rel. 16 NR-U, PRACH is limited to a 20 MHz band.

Given the relatively low PSD limitation on the 6 GHz band (e.g., 11 dB lower at UE side and 5 dB lower at gNB side) , the link budget may be reduced. The disclosure relates in some aspects to regaining this loss of link budget. Also, as indicated above, the uplink may be weaker (e.g., by 6 dB relatively) . The disclosure relates in some aspects to balancing the link budget between the downlink and the uplink.

PRACH is the first uplink transmission waveform. If PRACH does not have enough link budget, the UE cannot access the system. In 3GPP Rel. 16 NR-U, to have higher PRACH power under a PSD limitation, the PRACH design is revised by introducing a sequence of length 571 for 30 KHz and a sequence of length 1151 for 15 KHz. These sequences occupy about 48/96 RBs for 30KHz/15KHz respectively.

The disclosure relates in some aspects to increasing the effective transmit power by transmitting signals with a wider bandwidth (e.g., without making the sequence longer) . As mentioned above, the 3GPP Rel. 16 NR-U PRACH covers 20 MHz. This may be relatively low given the low PSD limitation. The disclosure thus relates in some aspects to a wider band PRACH. For example, as shown in Table 2, for a UE, an increase of 3 dBm may be achieved using a 40 MHz bandwidth instead of a 20 MHz bandwidth. In addition, an increase of 6 dBm may be achieved using an 80 MHz bandwidth instead of a 20 MHz bandwidth.

	20 MHz	40 MHz	80 MHz
UE
	12 dBm	15 dBm	18 dBm
gNB	18 dBm	21 dBm	24 dBm

TABLE 2

FIG. 5 illustrates an example of a repeated wideband PRACH waveform 500. A first PRACH part is sent on RB set 0, a second PRACH part is sent on RB set 1, and so on.As mentioned above, each RB set may have a 20 MHz bandwidth. Each repetition of the PRACH waveform may occupy 48 or 96 RBs out of the 20 MHz in some examples.

The disclosure relates in some aspects to techniques for selecting the particular RBs (e.g., the 48 or 96 RBs) within an RB set to use for sending each PRACH part. As mentioned above, the uplink BWP may be a multiple of 20 MHz.

In some examples, a system may specify (e.g., preconfigure) where the PRACH is to be located. For example, the PRACH transmission for a given set of 48 RBs may always be sent in a center portion of the 48 RBs.

In some examples, the network (e.g., a BS) may specify (e.g., by sending an indication) the location to be used for PRACH. In a first option, this information is included in the RMSI (e.g., for initial access) . In a second option, this information is specified by radio resource control (RRC) configuration. For example, an RRC message may configure the starting point of each set of the 48 RBs for a PRACH transmission.

In some examples, an RB set RRC configuration may be used to indicate the location of the PRACH. For example, the configuration may specify that the 48 RBs in the center portion of each RB set is to be used for a PRACH transmission. As another example, the configuration may specify that the 48 RBs in one end of each RB set is to be used for a PRACH transmission. For initial access, the RB set configuration may be included in the RMSI. For example, an RB set configuration may be included in the RMSI for the initial uplink BWP.

In practice, using the same preamble sequence across each 20 MHz RB set may adversely affect the peak-to-average power ratio (PAPR) for the PRACH transmission. The disclosure relates in some aspects to using different preamble sequences for different RB sets. For example, preamble sequence variation (e.g., preamble sequence ramping) may be used across different 20 MHz sub-bands.

In some examples, preamble sequence variation may involve cyclic shift variations between different 20 MHz sub-bands. For example, a specified preamble sequence may be used for the first RB set (e.g., RB 0) . For the RB sets that follow, different cyclic shifts may be applied to each of the different copies of the preamble sequence transmitted on different RB sets (e.g. RB set 1, RB set 2, etc. ) .

In some examples, preamble sequence variation may involve selecting different preamble sequences for different RB sets. A set of preamble sequences (e.g., up to 64 sequences) may be assigned for an RO. Different entries from the set may then be selected for different 20 MHz RB sets. The set can be a subset of the preamble sequences (e.g., all preamble sequences defined for contention-based random access (CBRA) ) .

NR systems may use a power ramping process for initial access PRACH transmission. Starting with the open loop power control, a UE picks an initial power level for the first PRACH transmission. After each transmission, the UE will wait for a msg2 from the gNB. If a msg2 is not received within a random access response (RAR) window, the UE may assume the PRACH power is not high enough to reach gNB. The UE may therefore send another PRACH at a higher (e.g., slightly higher) power level.

The disclosure relates in some aspects to using a wider band PRACH to provide additional power for the PRACH power ramping process. For example, use of wider band PRACH transmissions may be integrated into the power ramping process.

In some examples, if the open loop transmit power is low, the UE can start with a single PRACH transmission. If, after a few PRACH transmissions (e.g., with the transmit power increasing with each transmission) , the required PRACH transmit power exceeds the power that can be supported by single PRACH, the UE may transmit multiple PRACH sequences in FDM fashion.

FIG. 6 illustrates an example of this type of power ramping 600, where the different rows of blocks represent different PRACH transmissions. Initially, a PRACH 602 is transmitted at a certain transmit power on one RB set. Having not received msg2, a PRACH 604 may be transmitted at a higher transmit power on one RB set. Having still not received msg2, PRACHs (e.g., PRACH 606) may be transmitted at a still higher transmit power (e.g., the highest allowed transmit power) on two RB sets. Finally, if msg2 is still not received, PRACHs (e.g., PRACH 608) may transmitted on four RB sets. In some examples, the blocks in a given row in FIG. 6 (e.g., the third row including the PRACH 606 or the fourth row including the PRACH 608) may represent that the same amount of power and RBs are used for each RB set transmission.

In some examples, multiple PRACH transmissions may be integrated earlier into the power ramping process. Initially, if the open loop transmit power is low, the UE can start with single PRACH transmission. If msg2 is not received, the process can start using multiple PRACH transmissions (e.g., two RB sets) before the maximum transmit power limit is reached. Here, the UE can increase the transmit power and/or the number of frequency division multiplexed PRACH sequences as a power ramping technique.

The disclosure relates in some aspects to RO configurations for a multi-part PRACH. For example, a gNB may specify the preamble sequence to be transmitted in each FDM location so that the gNB is able to combine a multi-part PRACH for detection.

For a system that supports both single part PRACH transmission and multi-part PRACH transmission, the eNB may define how the preamble sequences are used. For a multi-part PRACH, the gNB may jointly detect all of the PRACH parts (combine the detection metric) to take advantage of the higher total transmit power of the multi-part PRACH transmission. In addition, the gNB may reserve ROs for each 20 MHz RB set.

In some examples, a gNB configures multiple frequency domain ROs, one in each 20MHz sub-band (e.g., 4 ROs over 80 MHz) . In some examples, these ROs may have gaps between them.

Separate preamble sequence spaces are defined for a single-part PRACH transmission versus a multi-part PRACH transmission. For example, sequences 0 -31 may be defined for a single-part PRACH, sequences 32 -40 may be defined for a two-part PRACH (e.g., on RB sets 0 and 1) , and sequences 41 -48 may be defined for a four-part PRACH (e.g., on RB sets 0, 1, 2, and 3) , while the remaining sequences can be used for CFRA.

For a single-part PRACH transmission, there are 4 ROs, and the UE can use any one of them for a PRACH transmission. For example, a UE may pick one of the ROs and one preamble sequence for the PRACH transmission.

For a multi-part PRACH transmission, there are bundled ROs, and the UE can use any one of them for a multi-part PRACH transmission. For example, a UE may pick one of the bundled ROs and one preamble sequence (e.g., a preamble sequence that is associated with ROs in the bundle) for each for PRACH transmission.

FIG. 7 illustrates examples of a single-part PRACH transmission 702, a two-part PRACH transmission 704, and a four-part PRACH transmission 706. For the single-part PRACH transmission 702, four ROs are allocated and a sequence 708 is sent in one of the ROs. For the two-part PRACH transmission 704, there are two 2-bundle ROs and

sequences

710 and 712 are sent in one of the bundles. For the four-part PRACH transmission 706, there is a 4-bundle RO and

sequences

714, 716, 718, and 720 are sent in the bundle.

As mentioned above, PRACH may be defined to use a 20 MHz bandwidth on an unlicensed band. In some examples, the LBT bandwidth is also 20 MHz. Thus, the PRACH may be transmitted in an all-or-nothing fashion. For example, the transmission may be made only if all of the 20 MHz RB sets pass the LBT test.

The disclosure relates in some aspects to selecting the resources to be used for PRACH based on the LBT results on the allocated sub-bands (e.g., RB sets) . Here, since the access delay requirement for PRACH may be relatively short (e.g., to ensure that a device can access a cell as soon as possible) , it is desirable to transmit the PRACH as soon as possible. That is, it may be desirable to not cancel a PRACH transmission if only some of the RB sets of the allocated bandwidth failed LBT. In scenarios where the wideband PRACH is highly repetitive in nature, sub-band based transmission of PRACH may be feasible.

Referring to FIG. 8, a UE may send PRACH RBs in the RB sets that passed the LBT operation. Support for this feature may be controlled by a gNB and may be subject to UE capability. For example, a gNB may signal (e.g., in a configuration message) whether it allows this feature. As another example, a UE may signal (e.g., in a capability message) whether it supports this feature.

FIG. 8 illustrates several examples of the sub-band transmission. In a first example 802, LBT passed for both RB sets, and therefore, the PRACH is sent in both RB Set 0 and RB set 1. In a second example 804, LBT failed for RB set 0 and passed for RB set 1. Therefore, the PRACH is sent only in RB Set 1.

FIG. 9 is a diagram illustrating an example of a hardware implementation for a wireless communication device 900 employing a processing system 914. For example, the wireless communication device 900 may be a user equipment (UE) or other device configured to wirelessly communicate with a base station, as discussed in any one or more of FIGs. 1 -8. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system 914 that includes one or more processors 904. In some implementations, the wireless communication device 900 may correspond to one or more of the scheduled entity 106 (e.g., a UE, etc. ) of FIG. 1 and/or the

UE

222, 224, 226, 228, 230, 232, 234, 238, 240, or 242 FIG. 2.

The wireless communication device 900 may be implemented with a processing system 914 that includes one or more processors 904. Examples of processors 904 include microprocessors, microcontrollers, digital signal processors (DSPs) , field programmable gate arrays (FPGAs) , programmable logic devices (PLDs) , state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. In various examples, the wireless communication device 900 may be configured to perform any one or more of the functions described herein. That is, the processor 904, as utilized in a wireless communication device 900, may be used to implement any one or more of the processes and procedures described below.

In this example, the processing system 914 may be implemented with a bus architecture, represented generally by the bus 902. The bus 902 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 914 and the overall design constraints. The bus 902 communicatively couples together various circuits including one or more processors (represented generally by the processor 904) , a memory 905, and computer-readable media (represented generally by the computer-readable medium 906) . The bus 902 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface 908 provides an interface between the bus 902 and a transceiver 910 and between the bus 902 and an interface 930. The transceiver 910 provides a communication interface or means for communicating with various other apparatus over a wireless transmission medium. In some examples, the wireless communication device may include two or more transceivers 910, each configured to communicate with a respective network type (e.g., terrestrial or non-terrestrial) . The interface 930 provides a communication interface or means of communicating with various other apparatus and devices (e.g., other devices housed within the same apparatus as the wireless communication device or other external apparatus) over an internal bus or external transmission medium, such as an Ethernet cable. Depending upon the nature of the apparatus, a user interface 912 (e.g., keypad, display, speaker, microphone, joystick) may also be provided. Of course, such a user interface 912 is optional, and may be omitted in some examples, such as an IoT device.

The processor 904 is responsible for managing the bus 902 and general processing, including the execution of software stored on the computer-readable medium 906. The software, when executed by the processor 904, causes the processing system 914 to perform the various functions described below for any particular apparatus. The computer-readable medium 906 and the memory 905 may also be used for storing data that is manipulated by the processor 904 when executing software.

One or more processors 904 in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium 906.

The computer-readable medium 906 may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip) , an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD) ) , a smart card, a flash memory device (e.g., a card, a stick, or a key drive) , a random access memory (RAM) , a read only memory (ROM) , a programmable ROM (PROM) , an erasable PROM (EPROM) , an electrically erasable PROM (EEPROM) , a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium 906 may reside in the processing system 914, external to the processing system 914, or distributed across multiple entities including the processing system 914. The computer-readable medium 906 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

The wireless communication device 900 may be configured to perform any one or more of the operations described herein (e.g., as described above in conjunction with FIGs. 1 -8 and as described below in conjunction with FIG. 10) . In some aspects of the disclosure, the processor 904, as utilized in the wireless communication device 900, may include circuitry configured for various functions.

The processor 904 may include communication and processing circuitry 941. The communication and processing circuitry 941 may include one or more hardware components that provide the physical structure that performs various processes related to wireless communication (e.g., signal reception and/or signal transmission) as described herein. The communication and processing circuitry 941 may further include one or more hardware components that provide the physical structure that performs various processes related to signal processing (e.g., processing a received signal and/or processing a signal for transmission) as described herein. In some examples, the communication and processing circuitry 941 may include two or more transmit/receive chains, each configured to process signals in a different RAT (or RAN) type. The communication and processing circuitry 941 may further be configured to execute communication and processing software 951 included on the computer-readable medium 906 to implement one or more functions described herein.

In some implementations where the communication involves receiving information, the communication and processing circuitry 941 may obtain information from a component of the wireless communication device 900 (e.g., from the transceiver 910 that receives the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium) , process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry 941 may output the information to another component of the processor 904, to the memory 905, or to the bus interface 908. In some examples, the communication and processing circuitry 941 may receive one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 941 may receive information via one or more channels. In some examples, the communication and processing circuitry 941 may include functionality for a means for receiving.

In some implementations where the communication involves sending (e.g., transmitting) information, the communication and processing circuitry 941 may obtain information (e.g., from another component of the processor 904, the memory 905, or the bus interface 908) , process (e.g., encode) the information, and output the processed information. For example, the communication and processing circuitry 941 may output the information to the transceiver 910 (e.g., that transmits the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium) . In some examples, the communication and processing circuitry 941 may send one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 941 may send information via one or more channels. In some examples, the communication and processing circuitry 941 may include functionality for a means for sending (e.g., means for transmitting) .

The processor 904 may include resource selection circuitry 942 configured to perform resource selection-related operations as discussed herein (e.g., selecting one or more RB sets to close a link to a BS) . The resource selection circuitry 942 may include functionality for a means for selecting at least one RB set. The resource selection circuitry 942 may further be configured to execute resource selection software 952 included on the computer-readable medium 906 to implement one or more functions described herein.

The processor 904 may include sequence generation circuitry 943 configured to perform sequence generation-related operations as discussed herein. For example, may generate a random access sequence based on one or more of a specified location, or cyclic shift ramping, or power ramping, etc. The sequence generation circuitry 943 may include functionality for a means for generating a PRACH sequence. The sequence generation circuitry 943 may further be configured to execute sequence generation software 953 included on the computer-readable medium 906 to implement one or more functions described herein.

FIG. 10 is a flow chart illustrating an example process 1000 for a wireless communication system in accordance with some aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process 1000 may be carried out by the wireless communication device 900 illustrated in FIG. 9. In some aspects, the wireless communication device may be a user equipment. In some examples, the process 1000 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block 1002, a wireless communication device may identify a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum. For example, the communication and processing circuitry 941 and transceiver 910, shown and described above in connection with FIG. 9, may receive an indication of candidate ROs from a BS. In some aspects, the shared radio frequency spectrum may include an unlicensed radio frequency spectrum. In some aspects, the wireless communication device may be a user equipment.

At block 1004, the wireless communication device may select at least one RB set of the plurality of RB sets. For example, the resource selection circuitry 942, shown and described above in connection with FIG. 9, may select a sufficient number of RB sets for a PRACH transmission to close a link to a BS. In some aspects, the at least one RB set may include a first RB set and a second RB set.

In some aspects, the method may further include, if a target transmit power for the PRACH transmission is greater than or equal to a threshold, selecting at least one third RB set of the plurality of RB sets for transmission of at least one third PRACH sequence.

At block 1006, the wireless communication device may send at least one PRACH sequence on the at least one RB set. For example, the sequence generation circuitry 943 in cooperation with the communication and processing circuitry 941 and transceiver 910, shown and described above in connection with FIG. 9, may encode and transmit a PRACH.

In some aspects, sending the at least one PRACH sequence on the at least one RB set may include sending a first PRACH sequence on the first RB set; and sending a second PRACH sequence on the second RB set. In some aspects, the first PRACH sequence may be different from the second PRACH sequence. In some aspects, the first PRACH sequence may be sent via a first center portion of the first RB set and the second PRACH sequence may be sent via a second center portion of the second RB set.

In some aspects, the first PRACH sequence may be based on a first cyclic shift of a PRACH preamble sequence; and the second PRACH sequence may be based on a second cyclic shift of the PRACH preamble sequence.

In some aspects, the first PRACH sequence may be based on a first PRACH preamble sequence for a first random access channel (RACH) occasion (RO) ; and the second PRACH sequence may be based on a second PRACH preamble sequence for a second RO.

In some aspects, the method may further include receiving an indication of a location for the first PRACH sequence in the first RB set; wherein sending the first PRACH sequence may be based on the location. In some aspects, the indication may specify that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set. In some aspects, the indication may be received via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) . In some aspects, the indication may be for an initial uplink bandwidth part (BWP) . In some aspects, the indication may be received via a radio resource control (RRC) message.

In some aspects, sending the at least one PRACH sequence on the at least one RB set may include sending a first PRACH sequence on a first RB set of the plurality of RB sets, the method further include determining that a maximum transmit power for the PRACH transmission within one RB set has been reached; and after determining that the maximum transmit power for the PRACH transmission within one RB set has been reached, concurrently sending the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.

In some aspects, sending the at least one PRACH sequence on the at least one RB set may include sending a first PRACH sequence on a first RB set of the plurality of RB sets, the method further include determining that a response to the first PRACH sequence was not received; and after determining that the response to the first PRACH sequence was not received, concurrently sending the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.

In some aspects, the method may further include receiving a configuration of at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission; and generating the at least one PRACH sequence based on the at least one preamble sequence; wherein selecting the at least one RB set of the plurality of RB sets may be based on the at least one RO.

In some aspects, the method may further include receiving a configuration of, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence; and generating the at least one PRACH sequence based on the at least one preamble sequence; wherein selecting the at least one RB set of the plurality of RB sets may be based on the first RO and the second RO. In some aspects, the first RO and the second RO might not be continuous in frequency.

In some aspects, the method may further include receiving a configuration of, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence; and generating the at least one PRACH sequence based on the at least one preamble sequence; wherein selecting the at least one RB set of the plurality of RB sets may be based on the first RO, the second RO, the third RO, and the fourth RO.

In some aspects, the method may further include determining, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device; determining, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is not available for use by the wireless communication device; wherein, as a result of determining that the first RB set is available for use and determining that the second RB set is not available for use, the sending of the at least one PRACH sequence may include sending the at least one PRACH sequence on the first RB set.

In some aspects, the method may further include determining, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device; determining, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is available for use by the wireless communication device; wherein, as a result of determining that the first RB set is available for use and determining that the second RB set is available for use, the sending of the at least one PRACH sequence may include sending the at least one PRACH sequence on the first RB set and the second RB set.

In some aspects, the method may further include receiving a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and receiving a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration may be different from the first PUSCH configuration. In some aspects, the first PUSCH configuration specifies at least one of a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof; the second PUSCH configuration specifies at least one of a second MCS, a second TBS, a second time-frequency domain resource allocation, or any combination thereof; and the second MCS may be lower than the first MCS and/or the second TBS may be smaller than the first TBS and/or the second time-frequency domain resource allocation may be larger than the first time-frequency domain resource allocation.

In some aspects, the method may further include sending first PUSCH information based on the first PUSCH configuration on the first RB set after sending a first PRACH sequence on the first RB set.

In some aspects, the method may further include sending first PUSCH information based on the second PUSCH configuration on the second RB set after sending a first PRACH sequence on the second RB set; and sending second PUSCH information based on the second PUSCH configuration on the third RB set after sending the second PRACH sequence on the third RB set.

In some aspects, the method may further include determining that PUSCH information would not be decodable at a receiver if a two-step random access channel (RACH) procedure is used with the first RB set and the second RB set; and switching to a four-step RACH procedure based on the determining that the PUSCH information would not be decodable.

FIG. 11 is a conceptual diagram illustrating an example of a hardware implementation for base station (BS) 1100 employing a processing system 1114. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a processing system 1114 that includes one or more processors 1104. In some implementations, the BS 1100 may correspond to one or more of the scheduling entity 108 (e.g., a gNB, a transmit receive point, a UE, etc. ) of FIG. 1 and/or the

base station

210, 212, 214, or 218 of FIG. 2.

The processing system 1114 may be substantially the same as the processing system 914 illustrated in FIG. 9, including a bus interface 1108, a bus 1102, memory 1105, a processor 1104, and a computer-readable medium 1106. Furthermore, the BS 1100 may include an interface 1130 (e.g., a network interface) that provides a means for communicating with various other apparatus within a core network and with at least one radio access network. The processor 1104, as utilized in BS 1100, may be used to implement any one or more of the processes described below. The BS 1100 may be configured to perform any one or more of the operations described below in conjunction with FIG. 12.

In some aspects of the disclosure, the processor 1104 may include communication and processing circuitry 1141. The communication and processing circuitry 1141 may include one or more hardware components that provide the physical structure that performs various processes related to communication (e.g., signal reception and/or signal transmission) as described herein. The communication and processing circuitry 1141 may further include one or more hardware components that provide the physical structure that performs various processes related to signal processing (e.g., processing a received signal and/or processing a signal for transmission) as described herein. The communication and processing circuitry 1141 may further be configured to execute communication and processing software 1151 included on the computer-readable medium 906 to implement one or more functions described herein.

In some implementations where the communication involves receiving information, the communication and processing circuitry 1141 may obtain information from a component of the BS 1100 (e.g., from the transceiver 1110 that receives the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium) , process (e.g., decode) the information, and output the processed information. For example, the communication and processing circuitry 1141 may output the information to another component of the processor 1104, to the memory 1105, or to the bus interface 1108. In some examples, the communication and processing circuitry 1141 may receive one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 1141 may receive information via one or more channels. In some examples, the communication and processing circuitry 1141 may include functionality for a means for receiving.

In some implementations where the communication involves sending (e.g., transmitting) information, the communication and processing circuitry 1141 may obtain information (e.g., from another component of the processor 1104, the memory 1105, or the bus interface 1108) , process (e.g., encode) the information, and output the processed information. For example, the communication and processing circuitry 1141 may output the information to the transceiver 1110 (e.g., that transmits the information via radio frequency signaling or some other type of signaling suitable for the applicable communication medium) . In some examples, the communication and processing circuitry 1141 may send one or more of signals, messages, other information, or any combination thereof. In some examples, the communication and processing circuitry 1141 may send information via one or more channels. In some examples, the communication and processing circuitry 1141 may include functionality for a means for sending (e.g., means for transmitting) .

The processor 1104 may include resource allocation circuitry 1142 configured to perform resource allocation-related operations as discussed herein (e.g., scheduling candidate RBs sets for a random access transmission) . The resource allocation circuitry 1142 may include functionality for a means for generating a configuration of a plurality of RB sets available for a PRACH transmission. The resource allocation circuitry 1142 may further be configured to execute resource allocation software 1152 included on the computer-readable medium 1106 to implement one or more functions described herein.

The processor 1104 may include sequence processing circuitry 1143 configured to perform sequence processing-related operations as discussed herein (e.g., decoding received random access sequences) . The sequence processing circuitry 1143 may include functionality for a means for receiving information based on cyclic shift ramping. The sequence processing circuitry 1143 may further be configured to execute waveform processing software 1153 included on the computer-readable medium 1106 to implement one or more functions described herein.

FIG. 12 is a flow chart illustrating another example process 1200 for a wireless communication system in accordance with some aspects of the present disclosure. As described below, some or all illustrated features may be omitted in a particular implementation within the scope of the present disclosure, and some illustrated features may not be required for implementation of all embodiments. In some examples, the process 1200 may be carried out by the BS 1100 illustrated in FIG. 11. In some examples, the process 1200 may be carried out by any suitable apparatus or means for carrying out the functions or algorithm described below.

At block 1202, a BS may generate a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum. For example, the resource allocation circuitry 1142, shown and described above in connection with FIG. 11, may select ROs for a PRACH transmission by a wireless communication device. In some aspects, the shared radio frequency spectrum may include an unlicensed radio frequency spectrum.

In some aspects, the configuration identifies at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission. In some aspects, the configuration identifies, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence. In some aspects, the first RO and the second RO are not continuous in frequency. In some aspects, the configuration identifies, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence.

At block 1204, the BS may send the configuration to a wireless communication device. For example, the communication and processing circuitry 1141 and transceiver 1110, shown and described above in connection with FIG. 11, may send an indication of allocated ROs to a UE.

At block 1206, the BS may receive at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets. For example, the sequence processing circuitry 1143 in cooperation with the communication and processing circuitry 1141 and transceiver 1110, shown and described above in connection with FIG. 11, may monitor one or more RB sets (e.g., according to allocated ROs) for PRACH sequences and then decode any received PRACH sequences. In some aspects, the at least one RB set may include a first RB set and a second RB set.

In some aspects, receiving the at least one PRACH sequence on the at least one RB set may include receiving a first PRACH sequence on the first RB set; and receiving a second PRACH sequence on the second RB set. In some aspects, the first PRACH sequence may be different from the second PRACH sequence. In some aspects, the first PRACH sequence may be received via a first center portion of the first RB set; and the second PRACH sequence may be received via a second center portion of the second RB set.

In some aspects, the method may further include sending, to the wireless communication device, an indication of a location for the first PRACH sequence in the first RB set. In some aspects, the indication may specify that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set. In some aspects, the indication may be sent via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) . In some aspects, the indication may be for an initial uplink bandwidth part (BWP) . In some aspects, the indication may be sent via a radio resource control (RRC) message.

In some aspects, the method may further include sending, to the wireless communication device, a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and sending, to the wireless communication device, a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration may be different from the first PUSCH configuration. In some aspects, the first PUSCH configuration specifies at least one of a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof; the second PUSCH configuration specifies at least one of a second MCS, , asecond TBS, a second time-frequency domain resource allocation, or any combination thereof; and the second MCS may be lower than the first MCS and/or the second TBS may be smaller than the first TBS and/or the second time-frequency domain resource allocation may be larger than the first time-frequency domain resource allocation.

In some aspects, the method may further include receiving first PUSCH information based on the first PUSCH configuration on the first RB set after receiving a first PRACH sequence on the first RB set.

In some aspects, the method may further include receiving first PUSCH information based on the second PUSCH configuration on the second RB set after receiving a first PRACH sequence on the second RB set; and receiving second PUSCH information based on the second PUSCH configuration on the third RB set after receiving the second PRACH sequence on the third RB set.

III. ADDITIONAL ASPECTS

Several aspects of a wireless communication network have been presented with reference to an example implementation. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards.

By way of example, various aspects may be implemented within other systems defined by 3GPP, such as Long-Term Evolution (LTE) , the Evolved Packet System (EPS) , the Universal Mobile Telecommunication System (UMTS) , and/or the Global System for Mobile (GSM) . Various aspects may also be extended to systems defined by the 3rd Generation Partnership Project 2 (3GPP2) , such as CDMA2000 and/or Evolution-Data Optimized (EV-DO) . Other examples may be implemented within systems employing IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Ultra-Wideband (UWB) , Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

Within the present disclosure, the word “exemplary” is used to mean “serving as an example, instance, or illustration. ” Any implementation or aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects of the disclosure. Likewise, the term “aspects” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation. The term “coupled” is used herein to refer to the direct or indirect coupling between two objects. For example, if object A physically touches object B, and object B touches object C, then objects A and C may still be considered coupled to one another-even if they do not directly physically touch each other. For instance, a first object may be coupled to a second object even though the first object is never directly physically in contact with the second object. The terms “circuit” and “circuitry” are used broadly, and intended to include both hardware implementations of electrical devices and conductors that, when connected and configured, enable the performance of the functions described in the present disclosure, without limitation as to the type of electronic circuits, as well as software implementations of information and instructions that, when executed by a processor, enable the performance of the functions described in the present disclosure.

One or more of the components, steps, features and/or functions illustrated in FIGs. 1 -12 may be rearranged and/or combined into a single component, step, feature or function or embodied in several components, steps, or functions. Additional elements, components, steps, and/or functions may also be added without departing from novel features disclosed herein. The apparatus, devices, and/or components illustrated in FIGs. 1, 2, 9, and 11 may be configured to perform one or more of the methods, features, or steps escribed herein. The novel algorithms described herein may also be efficiently implemented in software and/or embedded in hardware.

It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of example processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” 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 cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

Claims

A method of communication at a wireless communication device, the method comprising:

identifying a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

selecting at least one RB set of the plurality of RB sets; and

sending at least one PRACH sequence on the at least one RB set.
The method of claim 1, wherein the at least one RB set comprises a first RB set and a second RB set.
The method of claim 2, wherein receiving the at least one PRACH sequence on the at least one RB set comprises:

receiving a first PRACH sequence on the first RB set; and

receiving a second PRACH sequence on the second RB set.
The method of claim 3, wherein the first PRACH sequence is different from the second PRACH sequence.
The method of claim 3, further comprising:

if a target transmit power for the PRACH transmission is greater than or equal to a threshold, selecting at least one third RB set of the plurality of RB sets for transmission of at least one third PRACH sequence.
The method of claim 3, wherein:

the first PRACH sequence is sent via a first center portion of the first RB set; and

the second PRACH sequence is sent via a second center portion of the second RB set.
The method of claim 3, further comprising:

receiving an indication of a location for the first PRACH sequence in the first RB set;

wherein sending the first PRACH sequence is based on the location.
The method of claim 7, wherein the indication specifies that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set.
The method of claim 7, wherein the indication is received via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) .
The method of claim 9, wherein the indication is for an initial uplink bandwidth part (BWP) .
The method of claim 7, wherein the indication is received via a radio resource control (RRC) message.
The method of claim 3, wherein:

the first PRACH sequence is based on a first cyclic shift of a PRACH preamble sequence; and

the second PRACH sequence is based on a second cyclic shift of the PRACH preamble sequence.
The method of claim 3, wherein:

the first PRACH sequence is based on a first PRACH preamble sequence for a first random access channel (RACH) occasion (RO) ; and

the second PRACH sequence is based on a second PRACH preamble sequence for a second RO.
The method of claim 1, wherein sending the at least one PRACH sequence on the at least one RB set comprises sending a first PRACH sequence on a first RB set of the plurality of RB sets, the method further comprising:

determining that a maximum transmit power for the PRACH transmission within one RB set has been reached; and

after determining that the maximum transmit power for the PRACH transmission within one RB set has been reached, concurrently sending the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.
The method of claim 1, wherein sending the at least one PRACH sequence on the at least one RB set comprises sending a first PRACH sequence on a first RB set of the plurality of RB sets, the method further comprising:

determining that a response to the first PRACH sequence was not received; and

after determining that the response to the first PRACH sequence was not received, concurrently sending the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.
The method of claim 1, further comprising:

receiving a configuration of at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission; and

generating the at least one PRACH sequence based on the at least one preamble sequence;

wherein selecting the at least one RB set of the plurality of RB sets is based on the at least one RO.
The method of claim 1, further comprising:

receiving a configuration of, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence; and

generating the at least one PRACH sequence based on the at least one preamble sequence;

wherein selecting the at least one RB set of the plurality of RB sets is based on the first RO and the second RO.
The method of claim 17, wherein:

the first RO and the second RO are not continuous in frequency.
The method of claim 1, further comprising:

receiving a configuration of, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence; and

generating the at least one PRACH sequence based on the at least one preamble sequence;

wherein selecting the at least one RB set of the plurality of RB sets is based on the first RO, the second RO, the third RO, and the fourth RO.
The method of claim 1, further comprising:

determining, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device; and

determining, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is not available for use by the wireless communication device;

wherein, as a result of determining that the first RB set is available for use and determining that the second RB set is not available for use, the sending of the at least one PRACH sequence comprises sending the at least one PRACH sequence on the first RB set.
The method of claim 1, further comprising:

determining, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device; and

determining, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is available for use by the wireless communication device;

wherein, as a result of determining that the first RB set is available for use and determining that the second RB set is available for use, the sending of the at least one PRACH sequence comprises sending the at least one PRACH sequence on the first RB set and the second RB set.
The method of claim 1, further comprising:

receiving a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and

receiving a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration is different from the first PUSCH configuration.
The method of claim 22, wherein:

the first PUSCH configuration specifies at least one of: a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof;

the second PUSCH configuration specifies at least one of: a second MCS, a second TBS, a second time-frequency domain resource allocation, or any combination thereof; and

the second MCS is lower than the first MCS and/or the second TBS is smaller than the first TBS and/or the second time-frequency domain resource allocation is larger than the first time-frequency domain resource allocation.
The method of claim 22, further comprising:

sending first PUSCH information based on the first PUSCH configuration on the first RB set after sending a first PRACH sequence on the first RB set.
The method of claim 22, further comprising:

sending first PUSCH information based on the second PUSCH configuration on the second RB set after sending a first PRACH sequence on the second RB set; and

sending second PUSCH information based on the second PUSCH configuration on the third RB set after sending a second PRACH sequence on the third RB set.
The method of claim 22, further comprising:

determining that PUSCH information would not be decodable at a receiver if a two-step random access channel (RACH) procedure is used with the second RB set and the third RB set; and

switching to a four-step RACH procedure based on the determining that the PUSCH information would not be decodable.
A wireless communication device, comprising:

a transceiver;

a memory; and

a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to:

identify a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

select at least one RB set of the plurality of RB sets; and

send, via the transceiver, at least one PRACH sequence on the at least one RB set.
The wireless communication device of claim 27, wherein the at least one RB set comprises a first RB set and a second RB set.
The wireless communication device of claim 28, wherein the processor and the memory are configured to:

receive a first PRACH sequence on the first RB set; and

receive a second PRACH sequence on the second RB set.
The wireless communication device of claim 29, wherein the first PRACH sequence is different from the second PRACH sequence.
The wireless communication device of claim 29, wherein the processor and the memory are configured to:

if a target transmit power for the PRACH transmission is greater than or equal to a threshold, select at least one third RB set of the plurality of RB sets for transmission of at least one third PRACH sequence.
The wireless communication device of claim 29, wherein:

the first PRACH sequence is sent via a first center portion of the first RB set; and

the second PRACH sequence is sent via a second center portion of the second RB set.
The wireless communication device of claim 29, wherein the processor and the memory are configured to:

receive an indication of a location for the first PRACH sequence in the first RB set; and

send the first PRACH sequence based on the location.
The wireless communication device of claim 33, wherein the indication specifies that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set.
The wireless communication device of claim 33, wherein the indication is received via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) .
The wireless communication device of claim 35, wherein the indication is for an initial uplink bandwidth part (BWP) .
The wireless communication device of claim 33, wherein the indication is received via a radio resource control (RRC) message.
The wireless communication device of claim 29, wherein:

the first PRACH sequence is based on a first cyclic shift of a PRACH preamble sequence; and

the second PRACH sequence is based on a second cyclic shift of the PRACH preamble sequence.
The wireless communication device of claim 29, wherein:

the first PRACH sequence is based on a first PRACH preamble sequence for a first random access channel (RACH) occasion (RO) ; and

the second PRACH sequence is based on a second PRACH preamble sequence for a second RO.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

send a first PRACH sequence on a first RB set of the plurality of RB sets;

determine that a maximum transmit power for the PRACH transmission within one RB set has been reached; and

after the determination that the maximum transmit power for the PRACH transmission within one RB set has been reached, concurrently send the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

send a first PRACH sequence on a first RB set of the plurality of RB sets;

determine that a response to the first PRACH sequence was not received; and

after the determination that that the response to the first PRACH sequence was not received, concurrently send the first PRACH sequence on the first RB set and a second PRACH sequence on a second RB set of the plurality of RB sets.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

receive a configuration of at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission;

generate the at least one PRACH sequence based on the at least one preamble sequence; and

select the at least one RB set of the plurality of RB sets based on the at least one RO.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

receive a configuration of, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence;

generate the at least one PRACH sequence based on the at least one preamble sequence; and

select the at least one RB set of the plurality of RB sets based on the first RO and the second RO.
The wireless communication device of claim 43, wherein:

the first RO and the second RO are not continuous in frequency.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

receive a configuration of, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence;

generate the at least one PRACH sequence based on the at least one preamble sequence; and

select the at least one RB set of the plurality of RB sets based on the first RO, the second RO, the third RO, and the fourth RO.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

determine, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device;

determine, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is not available for use by the wireless communication device; and

as a result of the determination that the first RB set is available for use and the determination that the second RB set is not available for use, send the at least one PRACH sequence on the first RB set.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

determine, based on a first resource contention procedure, that a first RB set of the plurality of RB sets is available for use by the wireless communication device;

determine, based on a second resource contention procedure, that a second RB set of the plurality of RB sets is available for use by the wireless communication device; and

as a result of the determination that the first RB set is available for use and the determination that the second RB set is available for use, send the at least one PRACH sequence on the first RB set and the second RB set.
The wireless communication device of claim 27, wherein the processor and the memory are configured to:

receive a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and

receive a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration is different from the first PUSCH configuration.
The wireless communication device of claim 48, wherein:

the first PUSCH configuration specifies at least one of: a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof;

the second PUSCH configuration specifies at least one of: a second MCS, a second TBS, a second time-frequency domain resource allocation, or any combination thereof; and

the second MCS is lower than the first MCS and/or the second TBS is smaller than the first TBS and/or the second time-frequency domain resource allocation is larger than the first time-frequency domain resource allocation.
The wireless communication device of claim 48, wherein the processor and the memory are configured to:

send first PUSCH information based on the first PUSCH configuration on the first RB set after sending a first PRACH sequence on the first RB set.
The wireless communication device of claim 48, wherein the processor and the memory are configured to:

send first PUSCH information based on the second PUSCH configuration on the second RB set after sending a first PRACH sequence on the second RB set; and

send second PUSCH information based on the second PUSCH configuration on the third RB set after sending a second PRACH sequence on the third RB set.
The wireless communication device of claim 48, wherein the processor and the memory are configured to:

determine that PUSCH information would not be decodable at a receiver if a two-step random access channel (RACH) procedure is used with the first RB set and the second RB set; and

switch to a four-step RACH procedure based on the determination that the PUSCH information would not be decodable.
A wireless communication device, comprising:

means for identifying a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

means for selecting at least one RB set of the plurality of RB sets; and

means for sending at least one PRACH sequence on the at least one RB set.
An article of manufacture for use by a wireless communication device in a wireless communication network, the article comprising:

a computer-readable medium having stored therein instructions executable by one or more processors of the wireless communication device to:

identify a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

select at least one RB set of the plurality of RB sets; and

send at least one PRACH sequence on the at least one RB set.
A method of communication at a base station, the method comprising:

generating a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

sending the configuration to a wireless communication device; and

receiving at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.
The method of claim 55, wherein the at least one RB set comprises a first RB set and a second RB set.
The method of claim 56, wherein receiving the at least one PRACH sequence on the at least one RB set comprises:

receiving a first PRACH sequence on the first RB set; and

receiving a second PRACH sequence on the second RB set.
The method of claim 57, wherein the first PRACH sequence is different from the second PRACH sequence.
The method of claim 57, wherein:

the first PRACH sequence is received via a first center portion of the first RB set; and

the second PRACH sequence is received via a second center portion of the second RB set.
The method of claim 57, further comprising:

sending, to the wireless communication device, an indication of a location for the first PRACH sequence in the first RB set.
The method of claim 60, wherein the indication specifies that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set.
The method of claim 60, wherein the indication is sent via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) .
The method of claim 62, wherein the indication is for an initial uplink bandwidth part (BWP) .
The method of claim 60, wherein the indication is sent via a radio resource control (RRC) message.
The method of claim 57, wherein:

the first PRACH sequence is based on a first cyclic shift of a PRACH preamble sequence; and

the second PRACH sequence is based on a second cyclic shift of the PRACH preamble sequence.
The method of claim 57, wherein:

the first PRACH sequence is based on a first PRACH preamble sequence for a first random access channel (RACH) occasion (RO) ; and

the second PRACH sequence is based on a second PRACH preamble sequence for a second RO.
The method of claim 55, wherein the configuration identifies at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission.
The method of claim 55, wherein the configuration identifies, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence.
The method of claim 68, wherein:

the first RO and the second RO are not continuous in frequency.
The method of claim 55, wherein the configuration identifies, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence.
The method of claim 55, further comprising:

sending, to the wireless communication device, a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and

sending, to the wireless communication device, a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration is different from the first PUSCH configuration.
The method of claim 71, wherein:

the first PUSCH configuration specifies at least one of: a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof;

the second PUSCH configuration specifies at least one of: a second MCS, a second TBS, a second time-frequency domain resource allocation, or any combination thereof; and

the second MCS is lower than the first MCS and/or the second TBS is smaller than the first TBS and/or the second time-frequency domain resource allocation is larger than the first time-frequency domain resource allocation.
The method of claim 71, further comprising:

receiving first PUSCH information based on the first PUSCH configuration on the first RB set after receiving a first PRACH sequence on the first RB set.
The method of claim 71, further comprising:

receiving first PUSCH information based on the second PUSCH configuration on the second RB set after receiving a first PRACH sequence on the second RB set; and

receiving second PUSCH information based on the second PUSCH configuration on the third RB set after receiving a second PRACH sequence on the third RB set.
A base station, comprising:

a transceiver;

a memory; and

a processor communicatively coupled to the transceiver and the memory, wherein the processor and the memory are configured to:

generate a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

send the configuration to a wireless communication device via the transceiver; and

receive, via the transceiver, at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.
The base station of claim 75, wherein the at least one RB set comprises a first RB set and a second RB set.
The base station of claim 76, wherein the processor and the memory are further configured to:

receive a first PRACH sequence on the first RB set; and

receive a second PRACH sequence on the second RB set.
The base station of claim 77, wherein the first PRACH sequence is different from the second PRACH sequence.
The base station of claim 77, wherein:

the first PRACH sequence is received via a first center portion of the first RB set; and

the second PRACH sequence is received via a second center portion of the second RB set.
The base station of claim 77, wherein the processor and the memory are further configured to:

send, to the wireless communication device, an indication of a location for the first PRACH sequence in the first RB set.
The base station of claim 80, wherein the indication specifies that the first PRACH sequence is to be sent via RBs in a center portion of the first RB set, via RBs at a beginning of the first RB set, or via RBs at an end of the first RB set.
The base station of claim 80, wherein the indication is sent via remaining system information (RMSI) on a physical downlink shared channel (PDSCH) .
The base station of claim 82, wherein the indication is for an initial uplink bandwidth part (BWP) .
The base station of claim 80, wherein the indication is sent via a radio resource control (RRC) message.
The base station of claim 77, wherein:

the first PRACH sequence is based on a first cyclic shift of a PRACH preamble sequence; and

the second PRACH sequence is based on a second cyclic shift of the PRACH preamble sequence.
The base station of claim 77, wherein:

the first PRACH sequence is based on a first PRACH preamble sequence for a first random access channel (RACH) occasion (RO) ; and

the second PRACH sequence is based on a second PRACH preamble sequence for a second RO.
The base station of claim 75, wherein the configuration identifies at least one random access channel (RACH) occasion (RO) and at least one preamble sequence for the PRACH transmission.
The base station of claim 75, wherein the configuration identifies, for a two-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, and at least one preamble sequence.
The base station of claim 88, wherein:

the first RO and the second RO are not continuous in frequency.
The base station of claim 75, wherein the configuration identifies, for a four-part PRACH transmission, a first random access channel (RACH) occasion (RO) , a second RO, a third RO, a fourth RO, and at least one preamble sequence.
The base station of claim 75, wherein the processor and the memory are further configured to:

send, to the wireless communication device, a first physical uplink shared channel (PUSCH) configuration for a two-step random access channel (RACH) transmission on a first RB set of the plurality of RB sets; and

send, to the wireless communication device, a second PUSCH configuration for two-step RACH transmissions on a second RB set and a third RB set of the plurality of RB sets, wherein the second PUSCH configuration is different from the first PUSCH configuration.
The base station of claim 91, wherein:

the first PUSCH configuration specifies at least one of: a first modulation and coding scheme (MCS) , a first transport block size (TBS) , a first time-frequency domain resource allocation, or any combination thereof;

the second PUSCH configuration specifies at least one of: a second MCS, , asecond TBS, a second time-frequency domain resource allocation, or any combination thereof; and

the second MCS is lower than the first MCS and/or the second TBS is smaller than the first TBS and/or the second time-frequency domain resource allocation is larger than the first time-frequency domain resource allocation.
The base station of claim 91, wherein the processor and the memory are further configured to:

receive first PUSCH information based on the first PUSCH configuration on the first RB set after receiving a first PRACH sequence on the first RB set.
The base station of claim 91, wherein the processor and the memory are further configured to:

receive first PUSCH information based on the second PUSCH configuration on the second RB set after receiving a first PRACH sequence on the second RB set; and

receive second PUSCH information based on the second PUSCH configuration on the third RB set after receiving a second PRACH sequence on the third RB set.
A base station, comprising:

means for generating a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

means for sending the configuration to a wireless communication device; and

means for receiving at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.
An article of manufacture for use by a base station in a wireless communication network, the article comprising:

a computer-readable medium having stored therein instructions executable by one or more processors of the base station to:

generate a configuration of a plurality of resource block (RB) sets available for a physical random access channel (PRACH) transmission on a shared radio frequency spectrum;

send the configuration to a wireless communication device; and

receive at least one PRACH sequence from the wireless communication device via at least one RB set of the plurality of RB sets.