Patent Description:
In Fifth Generation (<NUM>) New Radio (NR) networks, wireless devices can communicate with each other using beamformed communication that uses directional transmission and reception techniques. In some examples, a transmitting device may use a number of beams in different directions to communicate with a receiver. In some cases, the receiver can determine the perceived interference and report back the interference level and/or beam measurements to the transmitting device. Then, the receiver and the transmitting device can cooperate together to block or avoid the interferers to improve communication using beamforming. However, in some cases, the receiver may not be able to detect the interferers that affect the transmitting device in all scenarios.

<CIT> discloses a user equipment (UE) in beam-centric telecommunications cell that may use a variety of listen-before-talk (LBT) procedures and hybrid channel access procedures for uplink transmissions that are on different beams and configured or scheduled in contiguous or non-contiguous mode. The UE behavior may be based on the LBT result across the different beams. The gNB may indicate LBT occasions to UEs. The UL numerology may be adjusted without LBT while near the end of a gNB's maximum channel occupancy time (MCOT). A gNB may use LBT procedures, before down link transmissions, using data, control, and reference signals, etc., across different beams.

While aspects and examples 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, and packaging arrangements. For example, examples and/or uses may come about via integrated chip examples 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 examples. 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.

The electromagnetic spectrum is often subdivided, based on frequency/wavelength, into various classes, bands, channels, etc. In <NUM> New Radio (NR) two initial operating bands have been identified as frequency range designations FR1 (<NUM> - <NUM>) and FR2 (<NUM> - <NUM>). It should be understood that although a portion of FR1 is greater than <NUM>, FR1 is often referred to (interchangeably) as a "Sub-<NUM>" band in various documents and articles.

In addition, higher frequency bands are currently being explored to extend <NUM> New Radio (NR) operation beyond <NUM>. For example, three higher operating bands have been identified as frequency range designations FR4-a or FR4-<NUM> (<NUM> - <NUM>), FR4 (<NUM> - <NUM>), and FR5 (<NUM> - <NUM>).

The Fifth Generation (<NUM>) New Radio (NR) networks (or simply referred to as <NUM> or NR networks) can be deployed using various frequency bands defined in the NR specifications. A transmission using higher frequencies (e.g., FR2 or above) has higher attenuation or pathloss than one using lower frequencies (e.g., FR1). A transmitting device can overcome the attenuation or pathloss using a directional transmission technique such as beamforming that transmits the signal in one or more highly focused beams to overcome propagation losses. A beam is a directional signal that can be generated by combining elements in an antenna array in such a way that signals at particular angles experience constructive interference while others experience destructive interference. A transmitting device can control the phase and relative amplitude of the signal at each transmitter (e.g., antenna) in order to create a pattern of constructive and destructive interference in the wavefront. In general, a receiver is in a better position than the transmitting device to detect and measure any interference to the beam(s). The receiver can report the interference, if any, back to the transmitting device to facilitate cooperative or receiver (Rx)-assisted interference management (e.g., interference mitigation) with the transmitting device. However, in some cases, the receiver may not be able to detect the interference due to the directional nature of beamformed communication, for example, using higher frequencies (e.g., FR2).

One aspect of the disclosure provides a method of accessing a channel in wireless communication. Using the method, an apparatus selects a plurality of first beams for performing a spectrum sensing procedure to access a spectrum. The spectrum may be shared with other devices from a different network. The apparatus performs the spectrum sensing procedure on the plurality of first beams in a sensing period of a first frame period. The first beams may be millimeter wave (mmW) beams. The apparatus selects one or more transmit beams from the plurality of first beams for accessing the spectrum, based on a result of the spectrum sensing procedure. Then, the apparatus transmits a signal in the first frame period using the one or more selected transmit beams. The apparatus may use the signal to reserve the spectrum in the selected beam.

Another aspect of the disclosure provides an apparatus for wireless communication. The apparatus includes a communication interface configured to access a spectrum, a memory, and a processor operatively coupled with the communication interface and the memory. The processor and the memory are configured to select a plurality of first beams for performing a spectrum sensing procedure to access the spectrum. The processor and the memory are further configured to perform the spectrum sensing procedure on the plurality of first beams in a sensing period of a first frame period. The processor and the memory are further configured to select one or more transmit beams from the plurality of first beams for accessing the spectrum, based on a result of the spectrum sensing procedure. The processor and the memory are further configured to transmit, via the communication interface, a signal in the first frame period using the one or more selected transmit beams. The apparatus may use the signal to reserve the spectrum in the selected beam.

Another aspect of the disclosure provides an apparatus for wireless communication using frame-based channel access. The apparatus includes means for selecting a plurality of first beams for performing a spectrum sensing procedure to access a spectrum. The apparatus further includes means for performing the spectrum sensing procedure on the plurality of first beams in a sensing period of a first frame period. The apparatus further includes means for selecting one or more transmit beams from the plurality of first beams for accessing the spectrum, based on a result of the spectrum sensing procedure. The apparatus further includes means for transmitting a signal in the first frame period using the one or more selected transmit beams. The apparatus may use the signal to reserve the spectrum in the selected beam.

Another aspect of the disclosure provides a non-transitory computer-readable medium storing computer-executable code at an apparatus for wireless communication using frame-based channel access. The computer-executable code causes a processor to perform various operations. The processor selects a plurality of first beams for performing a spectrum sensing procedure to access a spectrum. The processor performs the spectrum sensing procedure on the plurality of first beams in a sensing period of a first frame period. The processor selects one or more transmit beams from the plurality of first beams for accessing the spectrum, based on a result of the spectrum sensing procedure. The processor transmits a signal in the first frame period using the one or more selected transmit beams. The apparatus may use the signal to reserve the spectrum in the selected beam.

Another aspect of the disclosure provides a method of wireless communication operable at a transmitting device. The transmitting device senses a spectrum in a plurality of first beams in a first frame period of a plurality of frame periods, and each of the plurality of first beams is configured for communication in a different respective direction. The transmitting device selects one or more beams of the plurality of first beams that are idle when sensing the spectrum in the first frame period. Then, the transmitting device transmits a signal in the first frame period using the selected one or more beams.

For selecting the one or more beams, the transmitting device may detect the signal energy of the one or more beams, and determine that the one or more beams are idle when the detected signal energy is less than a predetermined threshold. The first frame period may include a plurality of sensing slots and a time interval after the plurality of sensing slots for transmitting the signal. For sensing the spectrum, the transmitting device may sense the spectrum using a different beam of the plurality of first beams in a different respective sensing slot of the plurality of sensing slots.

The transmitting device may sense the spectrum using a plurality of second beams in a second frame period of the plurality of frame periods. The plurality of second beams may include at least one beam that is different from the plurality of first beams.

The transmitting device may sense the spectrum in the plurality of first beams in a second frame period of the plurality of frame periods. The sensing of the plurality of first beams follows a first sequence of the plurality of first beams in the first frame period and a second sequence of the plurality of first beams in the second frame period. The first sequence is different from the second sequence. The second sequence may be derived from the first sequence based on a round-robin algorithm.

Each frame period of the plurality of frame periods may further include an idle period configured to prevent signal transmission associated with a predetermined beam or beam group. For transmitting the signal, the transmitting device may transmit a reservation message in the first frame period to reserve the one or more beams for communication in the first frame period. For selecting the one or more beams, the transmitting device may determine that the one or more beams are available for communication without receiving feedback on the one or more beams from a wireless device.

Another aspect of the present disclosure provides an apparatus for wireless communication. The apparatus includes a communication interface configured to access a spectrum, a memory, and a processor operatively coupled with the communication interface and the memory. The processor and the memory are configured to sense the spectrum in a plurality of first beams in a first frame period of a plurality of frame periods, each of the plurality of first beams configured for communication in a different respective direction. The processor and the memory are further configured to select one or more beams of the plurality of first beams that are idle when sensing the spectrum in the first frame period. The processor and the memory are further configured to transmit a signal in the first frame period using the selected one or more beams.

Aspects of the present disclosure provide a method of frame-based channel access in a wireless communication network using transmitter-side only channel sensing. With transmitter-side (Tx-side) only channel sensing, the transmitting device can determine whether or not the spectrum is idle on one or more beams without using beam feedback or measurements from other network nodes (e.g., a receiver) that may communicate with the transmitting device using the one or more beams. In some aspects, a transmitting device may use the frame-based channel access mode with Tx-side only sensing in a network that uses an unlicensed or shared spectrum. The frame-based channel access mode described herein may use a fixed frame period that includes an initial sensing period for beam-based signal sensing and an idle period at the end of the frame to facilitate spectrum sharing. In some aspects, the transmitting device may be a <NUM> New Radio (NR) network node that utilizes various frequency bands, possibly including FR2 or higher frequency bands, for beam based communication.

As one example, the RAN <NUM> may operate according to <NUM>rd Generation Partnership Project (3GPP) New Radio (NR) specifications, often referred to as <NUM> or NR. The 3GPP refers to this hybrid RAN as a next-generation RAN or NG-RAN.

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), a transmission and reception point (TRP), or some other suitable terminology. In some examples, a base station may include two or more TRPs that may be collocated or non-collocated. Each TRP may communicate on the same or different carrier frequency within the same or different frequency band.

The radio access network <NUM> 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 (e.g., a mobile apparatus) that provides a user with access to network services. The UE may communicate with the RAN <NUM> using various licensed or unlicensed frequencies.

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, etc. Still further, a mobile apparatus may provide for connected medicine or telemedicine support, e.g., 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.

In some aspects, the scheduling entity can use a frame-based access mode to allocate resources for communication. The frame-based access mode will be described in more detail below.

<FIG> is an illustration of an example of a radio access network (RAN) <NUM> according to some aspects of the disclosure. In some examples, the RAN <NUM> may be the same as the RAN <NUM> described above and illustrated in <FIG>. The geographic area covered by the RAN <NUM> 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> illustrates macrocells <NUM>, <NUM>, and <NUM>, and a small cell <NUM>, 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.

In <FIG>, two exemplary base stations <NUM> and <NUM> are shown in cells <NUM> and <NUM>; and a third exemplary base station <NUM> is shown controlling a remote radio head (RRH) <NUM> in cell <NUM>.

The base stations <NUM>, <NUM>, <NUM>, <NUM> provide wireless access points to a core network (e.g., core network <NUM>) for any number of mobile apparatuses.

Within the RAN <NUM>, the cells may include UEs that may be in communication with one or more sectors of each cell. Further, each base station <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> may be configured to provide an access point to a core network <NUM> (see <FIG>) for all the UEs in the respective cells. For example, UEs <NUM> and <NUM> may be in communication with base station <NUM>; UEs <NUM> and <NUM> may be in communication with base station <NUM>; UEs <NUM> and <NUM> may be in communication with base station <NUM> by way of RRH <NUM>; UE <NUM> may be in communication with base station <NUM>; and UE <NUM> may be in communication with mobile base station <NUM>. In some examples, the UEs <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and/or <NUM> may be the same as the UE/scheduled entity <NUM> described above and illustrated in <FIG>. The UEs may communicate with the base stations using one or more beams in, for example, FR1 and/or FR2 frequencies.

In a further aspect of the RAN <NUM>, 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 <NUM>, <NUM>, and <NUM>) may communicate with each other using peer to peer (P2P) or sidelink signals <NUM> without relaying that communication through a base station. In some examples, the UEs <NUM>, <NUM>, and <NUM> may each function as a scheduling entity or transmitting sidelink device and/or a scheduled entity or a receiving sidelink device to schedule resources and communicate sidelink signals <NUM> therebetween without relying on scheduling or control information from a base station. In other examples, two or more UEs (e.g., UEs <NUM> and <NUM>) within the coverage area of a base station (e.g., base station <NUM>) may also communicate sidelink signals <NUM> over a direct link (sidelink) without conveying that communication through the base station <NUM>. In this example, the base station <NUM> may allocate resources to the UEs <NUM> and <NUM> for the sidelink communication. In either case, such sidelink signaling <NUM> and <NUM> may be implemented in a P2P network, a device-to-device (D2D) network, vehicle-to-vehicle (V2V) network, a vehicle-to-everything (V2X), a mesh network, or other suitable direct link network.

In the radio access network <NUM>, 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, not illustrated, part of the core network <NUM> in <FIG>), which 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.

In various aspects of the disclosure, a radio access network <NUM> 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 <NUM> (illustrated as a vehicle, although any suitable form of UE may be used) may move from the geographic area corresponding to its serving cell <NUM> to the geographic area corresponding to a neighbor cell <NUM>. When the signal strength or quality from the neighbor cell <NUM> exceeds that of its serving cell <NUM> for a given amount of time, the UE <NUM> may transmit a reporting message to its serving base station <NUM> indicating this condition. In response, the UE <NUM> may receive a handover command, and the UE may undergo a handover to the cell <NUM>.

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 <NUM>, <NUM>, and <NUM>/<NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> 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 <NUM>) may be concurrently received by two or more cells (e.g., base stations <NUM> and <NUM>/<NUM>) within the radio access network <NUM>. 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 <NUM> and <NUM>/<NUM> and/or a central node within the core network) may determine a serving cell for the UE <NUM>. As the UE <NUM> moves through the radio access network <NUM>, the network may continue to monitor the uplink pilot signal transmitted by the UE <NUM>. 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 <NUM> may handover the UE <NUM> from the serving cell to the neighboring cell, with or without informing the UE <NUM>.

In various implementations, the air interface in the radio access network <NUM> may utilize licensed spectrum, unlicensed spectrum, or shared spectrum. A spectrum may include one or more frequency bands that may be used for wireless communication. 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.

In some aspects of the disclosure, a network node (e.g., a base station or UE) may use a spectrum sensing procedure to gain access to a shared or unlicensed spectrum in a synchronized network (e.g., RAN <NUM>). In a synchronized network, network devices transmit and receive signals based on a synchronized timing, for example, using frame based access. In one example, a spectrum sensing procedure may use a listen-before-talk (LBT) process or procedure that can be a non-scheduled, contention-based multiple access technology where a device monitors or senses a carrier or spectrum (e.g., on one or more beams) before transmitting a signal over the spectrum. Some LBT techniques utilize signaling, such as a request to send (RTS) and a clear to send (CTS), to reserve the channel for a given duration of time. In some examples, the transmitting device may transmit a reservation message to reserve a beam for communicating with another device or network node (e.g., UE) after determining that the spectrum is idle or available, without receiving any beam measurements or feedback from the other device or network node.

The air interface in the radio access network <NUM> may 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. Half-duplex emulation is frequently implemented for wireless links utilizing time division duplex (TDD). 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. In a wireless link, a full-duplex channel generally relies on physical isolation of a transmitter and receiver, and suitable interference cancellation technologies. Full-duplex emulation is frequently implemented for wireless links by utilizing frequency division duplex (FDD) or spatial division duplex (SDD). In FDD, transmissions in different directions may operate at different carrier frequencies (e.g., within paired spectrum). In SDD, transmissions in different directions on a given channel are separated from one another using spatial division multiplexing (SDM). In other examples, full-duplex communication may be implemented within unpaired spectrum (e.g., within a single carrier bandwidth), where transmissions in different directions occur within different sub-bands of the carrier bandwidth. This type of full-duplex communication may be referred to herein as sub-band full duplex (SBFD), also known as flexible duplex.

In some aspects of the disclosure, the scheduling entity and/or scheduled entity may be configured for beamforming and/or multiple-input multiple-output (MIMO) technology. <FIG> illustrates an example of a wireless communication system <NUM> supporting MIMO. In a MIMO system, a transmitter <NUM> includes multiple transmit antennas <NUM> (e.g., N transmit antennas) and a receiver <NUM> includes multiple receive antennas <NUM> (e.g., M receive antennas). Thus, there are N × M signal paths <NUM> from the transmit antennas <NUM> to the receive antennas <NUM>. Each of the transmitter <NUM> and the receiver <NUM> may be implemented, for example, within a scheduling entity <NUM>, a scheduled entity <NUM>, or any other suitable wireless communication device.

The use of such multiple antenna technology enables the wireless communication system to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. Spatial multiplexing may be used to transmit different streams of data, also referred to as layers, simultaneously on the same time-frequency resource. The data streams may be transmitted to a single UE to increase the data rate or to multiple UEs to increase the overall system capacity, the latter being referred to as multi-user MIMO (MU-MIMO). This is achieved by spatially precoding each data stream (i.e., multiplying the data streams with different weighting and phase shifting) and then transmitting each spatially precoded stream through multiple transmit antennas on the downlink. The spatially precoded data streams arrive at the UE(s) with different spatial signatures, which enables each of the UE(s) to recover the one or more data streams destined for that UE. On the uplink, each UE transmits a spatially precoded data stream, which enables the base station to identify the source of each spatially precoded data stream.

The number of data streams or layers corresponds to the rank of the transmission. In general, the rank of the MIMO system <NUM> is limited by the number of transmit or receive antennas <NUM> or <NUM>, whichever is lower. In addition, the channel conditions at the UE, as well as other considerations, such as the available resources at the base station, may also affect the transmission rank. For example, the rank (and therefore, the number of data streams) assigned to a particular UE on the downlink may be determined based on the rank indicator (RI) transmitted from the UE to the base station. The RI may be determined based on the antenna configuration (e.g., the number of transmit and receive antennas) and a measured signal-to-interference-and-noise ratio (SINR) on each of the receive antennas. The RI may indicate, for example, the number of layers that may be supported under the current channel conditions. The base station may use the RI, along with resource information (e.g., the available resources and amount of data to be scheduled for the UE), to assign a transmission rank to the UE.

In Time Division Duplex (TDD) systems, the UL and DL are reciprocal, in that each uses different time slots of the same frequency bandwidth. Therefore, in TDD systems, the base station may assign the rank for DL MIMO transmissions based on UL SINR measurements (e.g., based on a Sounding Reference Signal (SRS) transmitted from the UE or other pilot signal). Based on the assigned rank, the base station may then transmit CSI-RSs with separate C-RS sequences for each layer to provide for multilayer channel estimation. From the CSI-RS, the UE may measure the channel quality across layers and resource blocks and feed back the RI and a channel quality indicator (CQI) that indicates to the base station a modulation and coding scheme (MCS) to use for transmissions to the UE for use in updating the rank and assigning REs for future downlink transmissions.

In the simplest case, as shown in <FIG>, a rank-<NUM> spatial multiplexing transmission on a 2x2 MIMO antenna configuration will transmit one data stream from each transmit antenna <NUM>. Each data stream reaches each receive antenna <NUM> along a different signal path <NUM>. The receiver <NUM> may then reconstruct the data streams using the received signals from each receive antenna <NUM>.

Beamforming is a signal processing technique that may be used at the transmitter <NUM> or receiver <NUM> to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitter <NUM> and the receiver <NUM>. Beamforming may be achieved by combining the signals communicated via antennas <NUM> or <NUM> (e.g., antenna elements of an antenna array module) such that some of the signals experience constructive interference while others experience destructive interference. To create the desired constructive/destructive interference, the transmitter <NUM> or receiver <NUM> may apply amplitude and/or phase offsets to signals transmitted or received from each of the antennas <NUM> or <NUM> associated with the transmitter <NUM> or receiver <NUM>.

In <NUM> New Radio (NR) systems, particularly for NR systems using FR2 or higher frequency bands, beamformed signals may be utilized for most downlink channels, including the physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH). In addition, broadcast control information, such as the synchronization signal block (SSB), slot format indicator (SFI), and paging information, may be transmitted in a beam-sweeping manner to enable all scheduled entities (UEs) in the coverage area of a transmission and reception point (TRP) (e.g., a gNB) to receive the broadcast control information. In addition, for UEs configured with beamforming antenna arrays, beamformed signals may also be utilized for uplink channels, including the physical uplink control channel (PUCCH) and physical uplink shared channel (PUSCH). However, it should be understood that beamformed signals may also be utilized by enhanced mobile broadband (eMBB) gNBs for sub <NUM> systems (e.g., FR1). In addition, beamformed signals may further be utilized in D2D systems, such as NR sidelink (SL) or V2X, utilizing FR2.

<FIG> is a diagram illustrating communication between a base station <NUM> and a UE <NUM> using beamformed signals according to some aspects. The base station <NUM> may be any of the base stations (e.g., gNBs) or scheduling entities illustrated in <FIG> and/or <NUM>, and the UE <NUM> may be any of the UEs or scheduled entities illustrated in <FIG> and/or <NUM>. In some aspects, the base station <NUM> may communicate with the UE <NUM> using a frame-based access mode described herein.

The base station <NUM> may generally be capable of communicating with the UE <NUM> using one or more transmit beams, and the UE <NUM> may further be capable of communicating with the base station <NUM> using one or more receive beams. As used herein, the term transmit beam refers to a beam on the base station <NUM> that may be utilized for downlink or uplink communication with the UE <NUM>. In addition, the term receive beam refers to a beam on the UE <NUM> that may be utilized for downlink or uplink communication with the base station <NUM>.

In the example shown in <FIG>, the base station <NUM> is configured to generate a plurality of transmit beams 406a-<NUM>, each associated with a different spatial direction. In addition, the UE <NUM> is configured to generate a plurality of receive beams 408a-408e, each associated with a different spatial direction. It should be noted that while some beams are illustrated as adjacent to one another, such an arrangement may be different in different aspects. For example, transmit beams 406a-<NUM> transmitted during a same symbol may not be adjacent to one another. In some examples, the base station <NUM> and UE <NUM> may each transmit more or less beams distributed in all directions (e.g., <NUM> degrees) and in three-dimensions. In addition, the transmit beams 406a-<NUM> may include beams of varying beam width. For example, the base station <NUM> may transmit certain signals (e.g., SSBs) on wider beams and other signals (e.g., CSI-RSs) on narrower beams.

The base station <NUM> and UE <NUM> may select one or more transmit beams 406a-<NUM> on the base station <NUM> and one or more receive beams 408a-408e on the UE <NUM> for communication of uplink and downlink signals therebetween using a beam management procedure. In one example, during initial cell acquisition, the UE <NUM> may perform a P1 beam management procedure to scan the plurality of transmit beams 406a-<NUM> on the plurality of receive beams 408a-408e to select a beam pair link (e.g., one of the transmit beams 406a-<NUM> and one of the receive beams 408a-408e) for a physical random access channel (PRACH) procedure for initial access to the cell. For example, periodic SSB beam sweeping may be implemented on the base station <NUM> at certain intervals (e.g., based on the SSB periodicity). Thus, the base station <NUM> may be configured to sweep or transmit an SSB on each of a plurality of wider transmit beams 406a-<NUM> during the beam sweeping interval. The UE may measure the reference signal received power (RSRP) of each of the SSB transmit beams on each of the receive beams of the UE and select the transmit and receive beams based on the measured RSRP. In an example, the selected receive beam may be the receive beam on which the highest RSRP is measured and the selected transmit beam may have the highest RSRP as measured on the selected receive beam.

After completing the PRACH procedure, the base station <NUM> and UE <NUM> may perform a P2 beam management procedure for beam refinement at the base station <NUM>. For example, the base station <NUM> may be configured to sweep or transmit a CSI-RS on each of a plurality of narrower transmit beams 406a-<NUM>. Each of the narrower CSI-RS beams may be a sub-beam of the selected SSB transmit beam (e.g., within the spatial direction of the SSB transmit beam). Transmission of the CSI-RS transmit beams may occur periodically (e.g., as configured via radio resource control (RRC) signaling by the gNB), semi-persistently (e.g., as configured via RRC signaling and activated/deactivated via medium access control-control element (MAC-CE) signaling by the gNB), or aperiodically (e.g., as triggered by the gNB via downlink control information (DCI)). The UE <NUM> is configured to scan the plurality of CSI-RS transmit beams 406a-<NUM> on the plurality of receive beams 408a-408e. The UE <NUM> then performs beam measurements (e.g., RSRP, SINR, etc.) of the received CSI-RSs on each of the receive beams 408a-408e to determine the respective beam quality of each of the CSI-RS transmit beams 406a-<NUM> as measured on each of the receive beams 408a-408e.

The UE <NUM> can then generate and transmit a Layer <NUM> (L1) measurement report, including the respective beam index (e.g., CSI-RS resource indicator (CRI)) and beam measurement (e.g., RSRP or SINR) of one or more of the CSI-RS transmit beams 406a-<NUM> on one or more of the receive beams 408a-408e to the base station <NUM>. The base station <NUM> may then select one or more CSI-RS transmit beams on which to communicate downlink and/or uplink control and/or data with the UE <NUM>. In some examples, the selected CSI-RS transmit beam(s) have the highest RSRP from the L1 measurement report. Transmission of the L1 measurement report may occur periodically (e.g., as configured via RRC signaling by the gNB), semi-persistently (e.g., as configured via RRC signaling and activated/deactivated via MAC-CE signaling by the gNB), or aperiodically (e.g., as triggered by the gNB via DCI).

The UE <NUM> may further select a corresponding receive beam on the UE <NUM> for each selected serving CSI-RS transmit beam to form a respective beam pair link (BPL) for each selected serving CSI-RS transmit beam. For example, the UE <NUM> can utilize the beam measurements obtained during the P2 procedure or perform a P3 beam management procedure to obtain new beam measurements for the selected CSI-RS transmit beams to select the corresponding receive beam for each selected transmit beam. In some examples, the selected receive beam to pair with a particular CSI-RS transmit beam may be the receive beam on which the highest RSRP for the particular CSI-RS transmit beam is measured.

In some examples, in addition to performing CSI-RS beam measurements, the base station <NUM> may configure the UE <NUM> to perform SSB beam measurements and provide an L1 measurement report containing beam measurements of SSB transmit beams 406a-<NUM>. For example, the base station <NUM> may configure the UE <NUM> to perform SSB beam measurements and/or CSI-RS beam measurements for beam failure detection (BRD), beam failure recovery (BFR), cell reselection, beam tracking (e.g., for a mobile UE <NUM> and/or base station <NUM>), or other beam optimization purpose.

In addition, when the channel is reciprocal, the transmit and receive beams may be selected using an uplink beam management scheme. In an example, the UE <NUM> may be configured to sweep or transmit on each of a plurality of receive beams 408a-408e. For example, the UE <NUM> may transmit an SRS on each beam in different beam directions. In addition, the base station <NUM> may be configured to receive the uplink beam reference signals on a plurality of transmit beams 406a-<NUM>. The base station <NUM> then performs beam measurements (e.g., RSRP, SINR, etc.) of the beam reference signals on each of the transmit beams 406a-<NUM> to determine the respective beam quality of each of the receive beams 408a-408e as measured on each of the transmit beams 406a-<NUM>.

The base station <NUM> may then select one or more transmit beams on which to communicate downlink and/or uplink control and/or data with the UE <NUM>. In some examples, the selected transmit beam(s) have the highest RSRP. The UE <NUM> may then select a corresponding receive beam for each selected serving transmit beam to form a respective beam pair link (BPL) for each selected serving transmit beam, using, for example, a P3 beam management procedure, as described above.

In one example, a single CSI-RS transmit beam (e.g., beam 406d) on the base station <NUM> and a single receive beam (e.g., beam 408c) on the UE may form a single BPL used for communication between the base station <NUM> and the UE <NUM>. In another example, multiple CSI-RS transmit beams (e.g., beams 406c, 406d, and 406e) on the base station <NUM> and a single receive beam (e.g., beam 408c) on the UE <NUM> may form respective BPLs used for communication between the base station <NUM> and the UE <NUM>. In another example, multiple CSI-RS transmit beams (e.g., beams 406c, 406d, and 406e) on the base station <NUM> and multiple receive beams (e.g., beams 408c and 408d) on the UE <NUM> may form multiple BPLs used for communication between the base station <NUM> and the UE <NUM>. In this example, a first BPL may include transmit beam 406c and receive beam 408c, a second BPL may include transmit beam 406d and receive beam 408c, and a third BPL may include transmit beam 406e and receive beam 408d.

Various aspects of the present disclosure can be described with reference to an OFDM waveform, schematically illustrated in <FIG>. 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>, an expanded view of an exemplary subframe <NUM> (e.g., DL subframe) is illustrated, showing an OFDM resource grid <NUM>. 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 or tones of the carrier.

The resource grid <NUM> may be used to schematically represent time-frequency resources for a given antenna port. That is, in a MIMO implementation with multiple antenna ports available, a corresponding multiple number of resource grids <NUM> may be available for communication. The resource grid <NUM> is divided into multiple resource elements (REs) <NUM>. For example. , an RE, which is <NUM> subcarrier × <NUM> 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) <NUM>, which contains any suitable number of consecutive subcarriers in the frequency domain. In one example, an RB may include <NUM> 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 <NUM> entirely corresponds to a single direction of communication (either transmission or reception for a given device).

Scheduling of scheduled entities (e.g., UEs) for downlink, uplink, or sidelink transmissions typically involves scheduling one or more resource elements <NUM> within one or more sub-bands or bandwidth parts (BWPs). Thus, a UE generally utilizes only a subset of the resource grid <NUM>. 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. The RBs may be scheduled by a base station (e.g., gNB, eNB, etc.) or may be self-scheduled by a UE implementing D2D sidelink communication.

Each subframe <NUM> (e.g., a <NUM> subframe) may consist of one or multiple adjacent slots. In the example shown in <FIG>, one subframe <NUM> includes four slots <NUM>, 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 <NUM> or <NUM> OFDM symbols with a nominal CP. Additional examples may include mini-slots, sometimes referred to as shortened transmission time intervals (TTIs), having a shorter duration (e.g., one to three OFDM symbols). These mini-slots or shortened transmission time intervals (TTIs) may in some cases be transmitted occupying resources scheduled for ongoing slot transmissions for the same or for different UEs. Any number of resource blocks may be utilized within a subframe or slot.

An expanded view of one of the slots <NUM> illustrates the slot <NUM> including a control region <NUM> and a data region <NUM>. In general, the control region <NUM> may carry control channels (e.g., PDCCH), and the data region <NUM> 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 structure illustrated in <FIG> 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>, the various REs <NUM> within an RB <NUM> may be scheduled to carry one or more physical channels, including control channels, shared channels, data channels, etc. Other REs <NUM> within the RB <NUM> may also carry pilots or reference signals. 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 <NUM>.

In some examples, the slot <NUM> may be utilized for broadcast, multicast, groupcast, or unicast communication. For example, a broadcast, multicast, or groupcast communication may refer to a point-to-multipoint transmission by one device (e.g., a base station, UE, or other similar device) to other devices. Here, a broadcast communication is delivered to all devices, whereas a multicast communication is delivered to multiple intended recipient devices and a groupcast communication is delivered to a group of intended recipient devices. A unicast communication may refer to a point-to-point transmission by a one device to a single other device.

In an example of cellular communication over a cellular carrier via a Uu interface, for a DL transmission, the scheduling entity (e.g., a base station) may allocate one or more REs <NUM> (e.g., within the control region <NUM>) to carry DL control information including one or more DL control channels, such as a physical downlink control channel (PDCCH), to one or more scheduled entities (e.g., UEs). The PDCCH carries downlink control information (DCI) including but not limited to power control commands (e.g., one or more open loop power control parameters and/or one or more closed loop power control parameters), scheduling information, a grant, and/or an assignment of REs for DL and UL transmissions. The PDCCH may further carry 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..

The base station may further allocate one or more REs <NUM> (e.g., in the control region <NUM> or the data region <NUM>) to carry other DL signals, such as a demodulation reference signal (DMRS); a phase-tracking reference signal (PT-RS); a channel state information (CSI) reference signal (CSI-RS); and a synchronization signal block (SSB). SSBs may be broadcast at regular intervals based on a periodicity (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>). An SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast control channel (PBCH). A UE may utilize the PSS and SSS to achieve radio frame, subframe, slot, and symbol synchronization in the time domain, identify the center of the channel (system) bandwidth in the frequency domain, and identify the physical cell identity (PCI) of the cell.

The PBCH in the SSB may further include a master information block (MIB) that includes various system information, along with parameters for decoding a system information block (SIB). The SIB may be, for example, a SystemInformationType <NUM> (SIB1) that may include various additional system information. Examples of system information transmitted in the MIB may include, but are not limited to, a subcarrier spacing, system frame number, a configuration of a PDCCH control resource set (CORESET) (e.g., PDCCH CORESET0), and a search space for SIB1. Examples of additional system information transmitted in the SIB1 may include, but are not limited to, a random access search space, downlink configuration information, and uplink configuration information. The MIB and SIB1 together provide the minimum system information (SI) for initial access.

In an UL transmission, the scheduled entity (e.g., UE) may utilize one or more REs <NUM> to carry UL control information (UCI) including one or more UL control channels, such as a physical uplink control channel (PUCCH), to the scheduling entity. UCI 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. In some examples, the UCI 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 UCI, the scheduling entity may transmit downlink control information (DCI) that may schedule resources for uplink packet transmissions. UCI may also include HARQ feedback, channel state feedback (CSF), such as a CSI report, or any other suitable UCI.

In addition to control information, one or more REs <NUM> (e.g., within the data region <NUM>) may be allocated for data traffic. Such data traffic may be carried on one or more traffic channels, such as, for a DL transmission, a physical downlink shared channel (PDSCH); or for an UL transmission, a physical uplink shared channel (PUSCH). In some examples, one or more REs <NUM> within the data region <NUM> may be configured to carry other signals, such as one or more SIBs and DMRSs.

In an example of sidelink communication over a sidelink carrier via a PC5 interface, the control region <NUM> of the slot <NUM> may include a physical sidelink control channel (PSCCH) including sidelink control information (SCI) transmitted by an initiating (transmitting) sidelink device (e.g., V2X or other sidelink device) towards a set of one or more other receiving sidelink devices. The data region <NUM> of the slot <NUM> may include a physical sidelink shared channel (PSSCH) including sidelink data traffic transmitted by the initiating (transmitting) sidelink device within resources reserved over the sidelink carrier by the transmitting sidelink device via the SCI. Other information may further be transmitted over various REs <NUM> within slot <NUM>. For example, HARQ feedback information may be transmitted in a physical sidelink feedback channel (PSFCH) within the slot <NUM> from the receiving sidelink device to the transmitting sidelink device. In addition, one or more reference signals, such as a sidelink SSB and/or a sidelink CSI-RS, may be transmitted within the slot <NUM>.

The channels or carriers described above and illustrated in <FIG>, <FIG>, <FIG>, and <FIG> are not necessarily all the channels or carriers that may be utilized between a scheduling entity <NUM> and scheduled entities <NUM>, 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.

<FIG> is a block diagram illustrating an example of a hardware implementation for an apparatus <NUM> employing a processing system <NUM>. For example, the apparatus <NUM> may be a user equipment (UE) as illustrated in any one or more of <FIG>, <FIG>, <FIG>, and/or <NUM>. In another example, the apparatus <NUM> may be a base station as illustrated in any one or more of <FIG>, <FIG>, <FIG>, and/or <NUM>.

The apparatus <NUM> may be implemented with a processing system <NUM> that includes one or more processors <NUM>. Examples of processors <NUM> 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 apparatus <NUM> may be configured to perform any one or more of the functions described herein. That is, the processor <NUM>, as utilized in the apparatus <NUM>, may be used to implement any one or more of the processes and procedures described below and illustrated in <FIG>.

In this example, the processing system <NUM> may be implemented with a bus architecture, represented generally by the bus <NUM>. The bus <NUM> may include any number of interconnecting buses and bridges depending on the specific application of the processing system <NUM> and the overall design constraints. The bus <NUM> communicatively couples together various circuits including one or more processors (represented generally by the processor <NUM>), a memory <NUM>, and computer-readable media (represented generally by the computer-readable medium <NUM>). The bus <NUM> 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 <NUM> provides an interface between the bus <NUM> and a transceiver <NUM>. The transceiver <NUM> provides a communication interface or means for communicating with various other apparatus over a transmission medium using one or more antenna arrays <NUM>. An antenna array is a set of connected antenna elements that may work together as a single antenna to transmit or receive radio waves using one or more beams. Depending upon the nature of the apparatus, a user interface <NUM> (e.g., keypad, display, speaker, microphone, joystick) may also be provided. Of course, such a user interface <NUM> is optional, and may be omitted in some examples, such as a base station.

In some aspects of the disclosure, the processor <NUM> may include circuitry configured for various functions, including, for example, frame-based spectrum access with Tx-side sensing. For example, the circuitry may be configured to implement one or more of the functions described below in relation to <FIG>. The circuitry may include a beamforming circuit <NUM>, a spectrum sensing circuit <NUM>, and a communication circuit <NUM>.

The beamforming circuit <NUM> may be configured to perform various operations used for beamforming in wireless communication described herein. For example, the apparatus may use the beamforming circuit <NUM> to select a plurality of beams for accessing a spectrum via the transceiver <NUM> and antenna array <NUM> using a spectrum sensing procedure. The spectrum sensing circuit <NUM> may be configured to perform various operations used for sensing a spectrum to determine whether or not the spectrum is idle or available. For example, the apparatus may use the spectrum sensing circuit <NUM> to perform a spectrum sensing procedure to sense a spectrum on a plurality of beams. The apparatus may use a timer <NUM> (e.g., countdown timer) to keep track of a time interval used during spectrum sensing.

The communication circuit <NUM> may be configured to perform various operations used for wireless communication (e.g., UL and DL communication) described herein. For example, the apparatus may use the communication circuit <NUM> to select one or more transmit beams for accessing a spectrum based on a result of the spectrum sensing procedure, and transmit a signal (e.g., a reservation message) using the selected beam(s) or beam direction(s). The result may include the determination that the spectrum is idle on one or more beams.

One or more processors <NUM> in the processing system may execute software. The software may reside on a computer-readable medium <NUM>. The computer-readable medium <NUM> 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 <NUM> may reside in the processing system <NUM>, external to the processing system <NUM>, or distributed across multiple entities including the processing system <NUM>. The computer-readable medium <NUM> 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.

In one or more examples, the computer-readable storage medium <NUM> may include software configured for various functions, including, for example, frame base spectrum access with Tx side sensing. For example, the software may be configured to implement one or more of the functions described in relation to <FIG>. The software may include beamforming instructions <NUM>, spectrum sensing instructions <NUM>, and communication instructions <NUM>.

The beamforming instructions <NUM> may cause the apparatus to perform various operations used for beamforming described herein. For example, the beamforming instructions <NUM> may cause the apparatus to select a plurality of beams for accessing a spectrum using a spectrum sensing procedure. The spectrum sensing instructions <NUM> may cause the apparatus to perform various spectrum sensing operations described herein. In one example, the spectrum sensing instructions <NUM> may cause the apparatus to use LBT techniques or the like to sense a spectrum in a plurality of beams. The communication instructions <NUM> may cause the apparatus to perform various operations used for wireless communication described herein. For example, the communication instructions <NUM> may cause the apparatus to select one or more transmit beams for accessing a spectrum based on a result of the spectrum sensing procedure described herein, and transmit a signal using the selected transmit beam(s), for example, to reserve the spectrum.

In some aspects, network devices can use a frame-based channel access mode to access a wireless network (e.g., RAN <NUM>) in which access to the network is synchronized based on frame timing. <FIG> is a diagram illustrating an exemplary frame structure for using a frame-based channel access mode with transmit-side (Tx-side) only sensing. A transmitting device (e.g., gNB or UE) may use a spectrum sensing procedure (e.g., LBT techniques) to gain channel access to a shared or unlicensed spectrum. To that end, the transmitting device may sense the spectrum on different beams or beam directions in each frame period to determine whether or not the spectrum is idle (e.g., available, free, or otherwise not in use by other transmitting devices). Two exemplary frame periods <NUM> and <NUM> are shown in <FIG> for illustrating a frame-based access mode. Each frame period may have a fixed or predetermined duration. Each frame period includes a sensing period <NUM> (sensing interval) at the beginning of the frame and an idle period <NUM> at the end of the frame. If a transmitting device successfully gained access to the spectrum through spectrum sensing, the transmitting device may transmit a signal to a receiver in a time interval <NUM> between the sensing period <NUM> and idle period <NUM>.

The idle period <NUM> is a time period in which all or at least some network nodes or entities refrain from transmitting so that devices of another wireless network or RAN sharing the spectrum may gain access to the shared spectrum. In one aspect of the disclosure, all network nodes refrain from transmitting in the idle period for all beams. In another aspect of the disclosure, the idle period may be applied on a per beam or beam group basis. In this case, during the idle period, the transmitting device can transmit on one or more beams and does not transmit on one or more other beams.

In some aspects of the disclosure, the sensing period <NUM> may include multiple sensing slots in the time domain that provide multiple sensing opportunities on different beams in a time division multiplexing (TDM), spatial division multiplexing (SDM), or frequency division multiplexing (FDM) fashion. <FIG> illustrates an example of a sensing period using TDM. A sensing slot is a predetermined time interval for sensing the spectrum to determine if the spectrum is being used by other transmitting device(s) (e.g., UEs or base stations). The transmitting device may sense the spectrum on different beams using the sensing slots. In the first frame period <NUM>, the transmitting device may sense or detect transmissions or beams from other devices (e.g., other UEs or base stations) to determine whether or not the spectrum is idle or available. In this example, the sensing period <NUM> has three sensing slots. The transmitting device may use the first sensing slot to sense the spectrum on a first beam B1, the second sensing slot to sense the spectrum on a second beam B2, and the third sensing slot to sense the spectrum on a third beam B3. In the second frame period <NUM>, the transmitting device may use the sensing period <NUM> to sense the same beams used in the first frame period <NUM> or sense one or more different beams. In one example, the transmitting device may sense the same beams B1 and B2 in both sensing periods, but beam B3 in the first sensing period <NUM> and beam B4 in the second sensing period <NUM>.

In some examples, the network may configure an upper bound on the number of sensing slots (T) that can be included in a frame period. A transmitting device can sense up to K beams per time instance (e.g., a sensing slot) per antenna panel or array. An antenna panel can detect or sense a predetermined beam or beam direction. A transmitting device (e.g., gNB or UE) needing to access the spectrum may choose up to K*T beam(s) for channel sensing.

<FIG> is a flow chart illustrating an exemplary method <NUM> for determining a beam sensing order according to some aspects of the disclosure. In some examples, the method may be carried out by a transmitting device (e.g., gNB or UE) using the frame-based channel access mode as described above in relation to <FIG>. At block <NUM>, a transmitting device senses a spectrum on a number of beams (e.g., Tx beam or Rx beam) in a first frame period. For example, the first frame period may be the same as the first frame period <NUM> of <FIG>. In one example, the transmitting device can sense the spectrum on a number of beams (e.g., beams B1, B2, and B3) using a sensing period <NUM> of the first frame period. During sensing, the transmitting device can determine the signal strength or energy, if detected, of the beams in their respective sensing slots of the sensing period.

At decision block <NUM>, the transmitting device can determine whether to sense the spectrum using the same beams in a second frame period after the first frame period. For example, the second frame period may be the same as the second frame period <NUM> of <FIG>. If the transmitting device determines to sense the same beams, the method proceeds to block <NUM>; otherwise, if the transmitting device determines to sense one or more different beams, the method proceeds to block <NUM>.

At block <NUM>, the transmitting device senses the same beams (e.g., B1, B2, and B3) again in the second frame period. In one aspect of the disclosure, the transmitting device may sense the same beams B1, B2, and B3 in the second frame period using the same sensing order or pattern (e.g., B1 in sensing slot <NUM>, B2 in sensing slot <NUM>, then B3 in sensing slot <NUM>) that was used in the first frame period. In some aspects of the disclosure, the transmitting device may use different beam sensing orders or patterns to sense the same beams in different frame periods.

In one aspect, the transmitting device may change the beam sensing sequence based on a round-robin pattern or algorithm. For example, the sensing sequence of the beams of a certain frame period may be derived from the sensing sequence of the same beams in an earlier frame period. In one example, the transmitting device may use the beam order B1, B2, and B3 in a first frame period; the beam order B2, B3, and B1 in a second frame period after the first frame period; and the beam order B3, B1, and B2 in a third frame period after the second frame period.

In one aspect, the transmitting device may randomize the beam sensing sequence in each frame period so that the beam sensing orders between the frame periods do not have any particular sensing orders or patterns. Randomizing or randomly changing the beam sensing orders or patterns can enable the transmitting device to detect and/or avoid a periodic interferer that shares the same spectrum and can use one or more particular beams.

At block <NUM>, the transmitting device senses the spectrum using different beams in the second frame period. The transmitting device may select a set of beams that are different from the set of beams sensed in the first frame period. For example, the transmitting device may be capable of using X number of beams (e.g., beams B1, B2, B3, and B4) for wireless communication. The transmitting device may sense the spectrum using a first subset (e.g., beams B1, B2, and B3) of the X number of beams in the first frame period, and sense a second subset (e.g., beams B1, B2, and B4) of the X number of beams in the second frame period. The first subset and the second subset have at least one different beam.

<FIG> is a diagram illustrating an exemplary spectrum sensing procedure according to some aspects of the present disclosure. In one example, a transmitting device (e.g., gNB or UE) may perform a spectrum sensing procedure or process in each sensing slot of a sensing period to determine if a channel is idle or a beam is available. In some examples, the spectrum sensing procedure may include a listen-before-talk (LBT) procedure that may or may not use random back-off when contention is detected. Three exemplary sensing slots <NUM>, <NUM>, and <NUM> are illustrated in <FIG>. In one example, these sensing slots may correspond to the sensing slots in the sensing period <NUM> or <NUM> illustrated in <FIG>. In each sensing slot, the transmitting device may perform the spectrum sensing procedure to determine if the beam associated with the sensing slot is silent or not used by other transmitting devices (e.g., UE or gNB) that may or may not belong to the same network. For example, the spectrum sensing procedure may include a clear channel assessment (CCA) of the channel. During CCA, the transmitting device can listen or detect the signal energy of any signal or beam transmitted from other devices, for example, network nodes of a different network sharing the same spectrum.

At block <NUM>, the transmitting device may detect the signal energy within a particular beam associated with the current sensing slot. For example, the transmitting device may use an antenna panel or array that is configured to detect the wireless signal energy of certain beam(s). At decision block <NUM>, the transmitting device determines whether or not the signal energy is greater than a predetermined threshold. At block <NUM>, if the detected signal energy (e.g., received signal strength indicator (RSSI)) is greater than the predetermined threshold, the spectrum (e.g., channel or beam) is considered idle or available. However, at block <NUM>, if the detected signal energy (e.g., RSSI) is not greater than the predetermined threshold, the spectrum is considered busy or not available.

In one aspect, the transmitting device may use a countdown timer in the spectrum sensing procedure to determine whether the spectrum or beam is idle. In the example shown in <FIG>, the countdown timer can count down from <NUM> to <NUM> corresponding to a predetermined time duration. In other examples, the countdown timer may be configured to use any desired duration. If the detected signal energy stays below the energy threshold throughout the countdown, the transmitting device considers the sensed channel or beam to be idle and may transmit a reservation message or signal <NUM> to reserve the sensed channel or beam. In some aspects, the reservation message <NUM> may be any predetermined message or signal that is designed to notify the receiving devices that the channel is reserved by the transmitting device. For example, the reservation message may be a transmission or message on a physical downlink control channel (PDCCH) or a physical sidelink control channel (PSSCH). The transmitting device may repeat the above-described spectrum sensing procedure in each sensing slot (sensing slots <NUM> and <NUM>) for different beams. In some aspects, the energy threshold may be the same for all beams. In some aspects, the transmitting device may use different thresholds for different beams.

<FIG> is a diagram illustrating another exemplary spectrum sensing procedure according to some aspects of the present disclosure. In one example, a transmitting device (e.g., gNB or UE) may perform a spectrum sensing procedure or process in each sensing slot of a sensing period to determine if beam is idle or free for access, for example, for accessing a communication channel between the transmitting device and a receiving device. Three exemplary sensing slots <NUM>, <NUM>, and <NUM> are illustrated in <FIG>. In this example, the transmitting device may sense the spectrum on beams B1, B2, and B3 in the sensing slots <NUM>, <NUM>, and <NUM>, respectively. If the transmitting device determines that any of the beams B1, B2, and B3 are available, the transmitting device transmits corresponding reservation messages <NUM> (illustrated as Tx B1, Tx B2, Tx B3 in <FIG>) to reserve the beams. Different from the example described above in relation to <FIG>, the transmitting device completes the sensing in all the sensing slots before transmitting the reservation messages <NUM> across the clear beams to reserve the spectrum. Similar to the example of <FIG>, the transmitting device may use a countdown counter <NUM> to determine whether or not a beam or channel is silent or idle in each sensing slot during a predetermined duration.

<FIG> is a diagram for illustrating an exemplary beam based idle period operation. Three exemplary frame periods are illustrated in <FIG>. These frame periods may be the same as the frame periods described above in relation to <FIG>. Each frame period has a sensing period <NUM> and an idle period <NUM>. During the sensing period <NUM>, a transmitting device (e.g., gNB or UE) may sense the spectrum on one or more beams, for example, using LBT techniques as described above. In one aspect, no transmission is allowed in the idle periods <NUM> to facilitate spectrum sharing with other networks. In some aspects, the idle periods <NUM> may operate on a per beam or beam group basis. When the idle periods operate on a per beam basis, no transmission is allowed for a predetermined beam out of all supported beams, and different idle periods may forbid transmission of different beams. In a per beam example, no transmission is allowed for a first beam (e.g., B1) in the idle period <NUM> of frame <NUM>, no transmission is allowed for a second beam (e.g., B2) in the idle period <NUM> of frame <NUM>, and no transmission is allowed for a third beam (e.g., B3) in the idle period <NUM> of frame <NUM>.

In some aspects, the idle period may operate on beam groups. In one example, a beam group may include a beam carrying a synchronization signal block (SSB) and other beams that are quasi co-located with the SSB beam. Two beams are quasi co-located when the beams exhibit similar channel condition. Therefore, the channel information estimated to detect one beam can help detect the other beam as well. An SSB carries the primary synchronization signal (PSS), secondary synchronization signal (SSS), and PBCH. In each idle period, a transmitting device cannot transmit in a predetermined beam group, but can transmit in other beam groups. Different idle periods can forbid the transmission of different beam groups. Per beam or beam group-based application of the idle periods may promote more efficient use of the spectrum for beam-based transmission. An interferer can still gain spectrum access during the idle periods due to the directional nature of beam-based transmission. In some aspects of the disclosure, an idle period for a specific beam may be configured in multiple consecutive frame periods (e.g., two or more frame periods). For example, referring to <FIG>, a transmitting device cannot transmit on the same beam in the idle periods <NUM> and <NUM> of two consecutive frame periods.

<FIG> is a diagram illustrating exemplary beam-based communication between a base station <NUM> and a user equipment (UE) <NUM> according to some aspects of the disclosure. The base station <NUM> may be any of the base stations or scheduling entities described above in relation to <FIG>. The UE <NUM> may be any of the UEs or scheduled entities described above in relation to <FIG>. The base station <NUM>, as a transmitting device, may use the frame-based access mode described above to gain access to a wireless spectrum (e.g., FR4 spectrum) that may be shared with another wireless network. For example, the base station <NUM> may determine that three beams (e.g., beams B1, B2, and B3) are idle or free during a sensing period of a frame. Therefore, the base station <NUM> can transmit a reservation signal or message on each beam to reserve the corresponding Tx beam for the current frame using a frame-based channel access mode. For example, the base station <NUM> transmits a first beam reservation message <NUM> (Beam <NUM> Msg) on beam B1, a second beam reservation message <NUM> (Beam <NUM> Msg) on beam B2, and a third beam reservation message <NUM> (Beam <NUM> Msg) on beam B3. These beam reservation messages notify other network nodes (e.g., UE <NUM>) that the base station is reserving these beams for a frame period.

If the UE <NUM> receives the reservation message on a Tx beam from the base station <NUM>, the UE may communicate with the base station <NUM> using a receive (Rx) beam corresponding to the Tx beam. For example, if the UE <NUM> receives a Tx beam B3 from the base station <NUM>, the UE may transmit to the base station <NUM> using an Rx beam B3 that has a beam direction corresponding to the Tx beam B3. In this case, the Tx beam and Rx beam can form a beam pair link (BPL). In some examples, the UE <NUM> may transmit a scheduling request (SR), a buffer status report (BSR), a sounding reference signal (SRS), PUCCH, PUSCH, etc., using the Rx beam. If the UE does not receive a reservation message from the base station (e.g., at least within the first X slots/symbols of a communication frame or slot), then the UE can consider that no beam is available to communicate with the base station.

In some aspects, the UE may transmit to the base station without first receiving a Tx beam reservation message from the base station. In some cases or exceptions, the UE may transmit a signal or channel related to some critical functions of the UE, for example, beam management, link establishment, maintenance, etc. In one aspect of the disclosure, an exception may be defined for a physical channel or signal, for example, a physical random access channel (PRACH) that is used in an initial access procedure, such as a random access procedure (RACH). In another aspect of the disclosure, an exception may be defined for a specific function, for example, BSR reporting and SR transmission. In another example, an exception may be defined for beam management SRS transmission, not including SRS for channel state information (CSI) reporting.

In some aspects of the disclosure, if a transmitting device (e.g., a base station or UE) detects interference during spectrum sensing, the transmitting device may share the information with other network nodes to facilitate beam management across the network. In some aspects of the disclosure, upon detection of a persistent interferer using the above described frame-based access mode, a transmitting device can switch to another spectrum access mode, for example, Rx-assisted spectrum access in which the receiver may send a report back to the transmitting device regarding interference detected by the receiver.

<FIG> is a flow chart illustrating an exemplary process1300 for frame-based channel access using Tx-only sensing according the claimed invention. 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 the implementation of all examples. In some examples, the process1300 may be carried out by apparatus <NUM> illustrated in <FIG>. In some examples, the process1300 may be carried out by any suitable apparatus or means for carrying out the functions or algorithms described below.

At block1302, an apparatus selects a plurality of first beams for performing a spectrum sensing procedure to access a spectrum. In some aspects, the first beams may be beams using FR2 frequencies. For example, the beamforming circuit <NUM> (see <FIG>) can provide the means for selecting the first beams (e.g., beams B1, B2, and B3 shown in a frame period <NUM> of <FIG>). The apparatus may select a subset of beams supported by the apparatus for performing the spectrum sensing procedure in a frame period. In one example, the first beams may include beams directed toward one or more predetermined directions. The apparatus may select the beams based on the known, estimated, and/or predicted locations of other devices or network nodes that may communicate with the apparatus.

At block1304, the apparatus performs the spectrum sensing procedure on the plurality of first beams in a sensing period of a first frame period. In one aspect, the spectrum sensing procedure may include an LBT procedure described above in relation to <FIG> and <FIG>. For example, the spectrum sensing circuit <NUM> can provide the means for performing the spectrum sensing procedure in the sensing period <NUM> of a frame period <NUM> (see <FIG>). The sensing period <NUM> has a number of sensing slots, and the apparatus may perform the spectrum sensing procedure for each beam in a corresponding sensing slot.

In the spectrum sensing procedure, the apparatus can sense a spectrum on a plurality of first beams on a first frame of a plurality of frames (e.g., frame periods <NUM> and <NUM> of <FIG>). Each of the plurality of frames include a sensing period (e.g., sensing periods <NUM> and <NUM> of <FIG>) for sensing the spectrum and an idle period (e.g., idle period <NUM>) for facilitating spectrum sharing with another wireless network.

In some aspects, the apparatus may determine that a channel or spectrum in a certain beam direction or beam is available based on the result of a clear channel assessment (CCA) procedure. <FIG> is a diagram illustrating a CCA procedure according to one aspect of the disclosure. At block <NUM>, the apparatus may check the signal energy (e.g., RSSI) detected for a beam. At block1404, if the signal energy is greater than a threshold, the apparatus determines that the channel is not idle or available in the direction of the beam. When the apparatus determines that a beam direction is not idle or available, it may indicate that another device is using the spectrum in the same or similar beam direction. At block1406, if the signal energy is not greater than a threshold, the apparatus determines that the channel is idle or available in the direction of the beam.

Referring back to <FIG>, at block1306, the apparatus selects one or more transmit beams for accessing the spectrum, based on a result of the spectrum sensing procedure. The apparatus may sense the spectrum in the sensing period of the first frame (e.g., first frame period <NUM>). In some examples, the transmit beams may be beams using FR2 frequencies. The communication circuit <NUM> and/or the beamforming circuit <NUM> can provide the means for selecting the transmit beams. The result of the spectrum sensing procedure may indicate one or more beams that are idle, or one or more beams are available. For example, a beam is idle or available when the apparatus cannot detect a signal with an energy greater than a predetermined threshold on the beam as described above in relation to <FIG>.

At block1308, the apparatus transmits a signal in the first frame period using the one or more selected transmit beams. The apparatus can transmit the signal between the sensing period (e.g., sensing period <NUM>) and idle period (e.g., idle period <NUM>) of the frame (e.g., frame period <NUM>). For example, the communication circuit <NUM> can provide the means for transmitting a signal via the transceiver <NUM> on one or more beams.

In one configuration, the apparatus <NUM> for wireless communication includes means for performing the various functions and processes described in relation to <FIG>. In one aspect, the aforementioned means may be the processor <NUM> shown in <FIG> configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a circuit or any apparatus configured to perform the functions recited by the aforementioned means.

Of course, in the above examples, the circuitry included in the processor <NUM> is merely provided as an example, and other means for carrying out the described functions may be included within various aspects of the present disclosure, including but not limited to the instructions stored in the computer-readable storage medium <NUM>, or any other suitable apparatus or means described in any one of the <FIG> and/or <NUM>, and utilizing, for example, the processes and/or algorithms described herein in relation to <FIG>.

Claim 1:
A method of wireless communication performed by a transmitting device in a wireless network, the method comprising:
sensing (<NUM>) a spectrum on a plurality of first beams in a first frame of a plurality of frames, each of the plurality of frames comprising a sensing period for sensing the spectrum and an idle period for enabling spectrum sharing with another wireless network;
selecting (<NUM>) one or more beams of the plurality of first beams based on a result of sensing the spectrum in the sensing period of the first frame;
transmitting (<NUM>) a signal in the first frame using the one or more beams in a time interval between the sensing period and the idle period of the first frame; and
refraining from transmitting a signal associated with a predetermined beam or beam group of the wireless network during the idle period.