Patent Application
20230361830
The technology discussed below relates generally to wireless communication systems, and more particularly, to wireless sidelink communication.
3rd Generation Partnership Project (3GPP) New Radio (NR) supports operation in unlicensed spectrum, intelligent transportation systems, Industrial Internet of Things, non-terrestrial networks, and vehicle-to-everything (V2X) application layer services, among other services and features. NR-based V2X builds on previous iterations of Long Term Evolution (LTE)-V2X, and provides advanced features, primarily in the area of low latency use cases. Enhanced NR system and new NR sidelinks have been introduced for V2X to meet certain requirements, such as a need to have a flexible design to support services with low latency and high reliability requirements, along with support for higher capacity and better coverage.
As the demand for mobile broadband access and sidelink communications continues to increase, research and development continue to advance wireless communication technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance mobile communications. Accordingly, the present disclosure addresses technologies and techniques to improve sidelink communications.
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 simplified form as a prelude to the more detailed description that is presented later.
In one example, a method for wireless communication at a user equipment (UE), is disclosed, comprising establishing a sidelink communication channel, and receiving time-division multiplexed (TDM) channel state information-reference signals (CSI-RS) mapped over a plurality of interlaced PSSCH resource blocks, wherein the mapped CSI-RS are interlaced with resource elements in at least a portion of the plurality of interlaced PSSCH resource blocks. The method may further comprise processing the CSI-RS received over the plurality of interlaced PSSCH resource blocks, and determining from the processing a channel quality of the sidelink channel from the portion of the plurality of interlaced PSSCH resource blocks comprising the mapped CSI-RS.
In another example, a user equipment (UE) for wireless communication, is disclosed, comprising, at least one processor, and a memory coupled to the at least one processor, the at least one processor and the memory configured to establish a sidelink communication channel, and receive time-division multiplexed (TDM) channel state information-reference signals (CSI-RS) mapped over a plurality of interlaced PSSCH resource blocks, wherein the mapped CSI-RS are interlaced with resource elements in at least a portion of the plurality of interlaced PSSCH resource blocks. The at least one processor and memory may be further configured to process the CSI-RS received over the plurality of interlaced PSSCH resource blocks, and determine from the processing a channel quality of the sidelink channel from the portion of the plurality of interlaced PSSCH resource blocks comprising the mapped CSI-RS.
In another example a non-transitory computer-readable medium is disclosed, storing computer-executable code at a user equipment (UE), comprising code for causing a computer to establish a sidelink communication channel, and receive time-division multiplexed (TDM) channel state information-reference signals (CSI-RS) mapped over a plurality of interlaced PSSCH resource blocks, wherein the mapped CSI-RS are interlaced with resource elements in at least a portion of the plurality of interlaced PSSCH resource blocks. The code may be further configured to process the CSI-RS received over the plurality of interlaced PSSCH resource blocks, and determine from the processing a channel quality of the sidelink channel from the portion of the plurality of interlaced PSSCH resource blocks comprising the mapped CSI-RS.
In another example, a user equipment (UE) for wireless communication is disclosed, comprising means for establishing a sidelink communication channel, and means for receiving time-division multiplexed (TDM) channel state information-reference signals (CSI-RS) mapped over a plurality of interlaced PSSCH resource blocks, wherein the mapped CSI-RS are interlaced with resource elements in at least a portion of the plurality of interlaced PSSCH resource blocks. The UE may also include means for processing the CSI-RS received over the plurality of interlaced PSSCH resource blocks; and means for determining from the processing a channel quality of the sidelink channel from the portion of the plurality of interlaced PSSCH resource blocks comprising the mapped CSI-RS.
These and other aspects of the disclosure will become more fully understood upon a review of the detailed description, which follows. Other aspects and features will become apparent to those of ordinary skill in the art, upon reviewing the following description of specific, exemplary aspects of the present disclosure in conjunction with the accompanying figures. While features of the present disclosure may be discussed relative to certain aspects and figures below, all aspects of the present disclosure can include one or more of the advantageous features discussed herein. In other words, while one or more aspects may be discussed as having certain advantageous features, one or more of such features may also be used in accordance with the various aspects of the disclosure discussed herein. In similar fashion, while exemplary aspects may be discussed below as a device, system, or method, it should be understood that such exemplary aspects can be implemented in various devices, systems, and methods.
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 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. Aspects described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, packaging arrangements. For example, aspects and/or uses may come about via integrated chip aspects 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 aspects 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 disclosure. 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 aspects. 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 aspects 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.
A Self Organizing Network (SON) refers to mobile network automation and minimization of human intervention in cellular/wireless network management. SON's objectives include: 1) bringing intelligence and autonomous adaptability into cellular networks; 2) reducing capital and operation expenditures; and 3) enhancing network performances in terms of network capacity, coverage, offered service/experience, etc. SON aims at improving spectral efficiency, simplifying management, and reducing the operation costs of next generation radio access networks (RANs).
Drive tests are used for collecting data of mobile networks. This data is needed for the configuration and maintenance of mobile networks, e.g., with respect to network capacity optimization, network coverage optimization, UE mobility optimization, and quality of service (QoS) verification. In order to execute drive tests, human effort is required. However, these measurements cover only a small piece of time and location of the network. Minimization of Drive Tests (MDT) enables operators to utilize UEs to collect radio measurements and associated location information, in order to assess network performance while reducing the operation expenditures associated with traditional drive tests. As such, MDT allows for standard UEs to be used for collecting/recording measurements and reporting the measurements to the operators while traditional drive tests make use of high developed measurement equipment.
In 3GPP NR, different types of UE reporting for measurements and events were developed with respect to SON and MDT. For example, the UE reporting of measurements and events may be directed to other scenarios such as Unified Access Control (UAC), which may enhance a user experience. UAC refers to a mechanism for regulating a UE's access to a network. For example, access control may be exercised by the network to reject the UE access or assign different types of priority to different types of user applications. Accordingly, aspects of the present disclosure relate to procedures, content, and triggers for UE reporting of UAC-related events.
In an aspect, operations related to a UE reporting control measurements (e.g., UAC measurements) to a network will be described. For example, the UE receives a configuration from the network indicating one or more measurements to record. The UE then performs an attempt to access the network and records the one or more measurements associated with the attempt. The UE reports, to the network, an availability of the one or more measurements after the attempt is performed. Thereafter, the UE receives a request for at least one measurement of the one or more measurements from the network and reports the at least one measurement to the network if the request for the at least one measurement is received.
In another aspect, operations related to a network device receiving a report of control measurements (e.g., UAC measurements) from a UE will be described. For example, the network sends a configuration to the UE indicating one or more measurements to record. The network device then receives, from the UE, a report indicating an availability of the one or more measurements recorded by the UE in association with an attempt to access the network device. The network device determines to receive at least one measurement of the one or more measurements, and sends, to the UE, a request to receive the at least one measurement. Thereafter, the network device receives, from the UE, a report including the at least one measurement in response to the request.
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
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, 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.
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 base station/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
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
In
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
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, 218, and 220 may be configured to provide an access point to a core network 102 (see
In some examples, a mobile network node (e.g., quadcopter 220) may be configured to function as a UE. For example, the quadcopter 220 may operate within cell 202 by communicating with base station 210.
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, not illustrated, part of the core network 102 in
In various aspects of the disclosure, 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.
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.
In order for transmissions over the radio access network 200 to obtain a low block error rate (BLER) while still achieving very high data rates, channel coding may be used. That is, wireless communication may generally utilize a suitable error correcting block code. In a typical block code, an information message or sequence is split up into code blocks (CBs), and an encoder (e.g., a CODEC) at the transmitting device then mathematically adds redundancy to the information message. Exploitation of this redundancy in the encoded information message can improve the reliability of the message, enabling correction for any bit errors that may occur due to the noise.
In early 5G NR specifications, user data is coded using quasi-cyclic low-density parity check (LDPC) with two different base graphs: one base graph is used for large code blocks and/or high code rates, while the other base graph is used otherwise. Control information and the physical broadcast channel (PBCH) are coded using Polar coding, based on nested sequences. For these channels, puncturing, shortening, and repetition are used for rate matching.
However, those of ordinary skill in the art will understand that aspects of the present disclosure may be implemented utilizing any suitable channel code. Various implementations of base stations (e.g., scheduling entities) 108 and UEs (e.g., scheduled entities) 106 may include suitable hardware and capabilities (e.g., an encoder, a decoder, and/or a CODEC) to utilize one or more of these channel codes for wireless communication.
The air interface in the radio access network 200 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. 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 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.
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.
In some examples, access to the air interface may be scheduled, where a scheduling entity (e.g., a base station) allocates resources (e.g., time—frequency 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 or scheduled entities utilize resources allocated by the scheduling entity.
Base stations are not the only entities that may function as a scheduling entity. 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). For example, UE 238 is illustrated communicating with UEs 240 and 242. In some examples, the UE 238 is functioning as a scheduling entity, while the UEs 240 and 242 may function as scheduled entities. In other examples, sidelink or other type of direct link signals may be communicated directly between UEs without necessarily relying on scheduling or control information from another entity. For example, UEs 238, 240, and 242 may communicate over a direct link in a device-to-device (D2D), peer-to-peer (P2P), vehicle-to-everything (V2X), 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 a scheduling entity (e.g., UE 238).
In some examples, UE 238 may be a transmitting sidelink device that reserves resources on a sidelink carrier for the transmission of sidelink signals to UEs 240 and 242 in a D2D or V2X network. Here, UEs 240 and 242 are each receiving sidelink devices. UEs 240 and 242 may, in turn, reserve additional resources on the sidelink carrier for subsequent sidelink transmissions.
In some examples, two or more UEs (e.g., UEs 226 and 228) within the coverage area of a serving base station 212 may communicate with both the base station 212 using cellular signals and with each other using sidelink signals 227 without relaying that communication through the base station. In this example, the base station 227 or one or both of the UEs 226 and 228 may function as scheduling entities to schedule sidelink communication between UEs 226 and 228. For example, UEs 126 and 128 may communicate sidelink signals 227 within a vehicle-to-everything (V2X) network.
Two primary technologies that may be used by V2X networks include dedicated short range communication (DSRC) based on IEEE 802.11p standards and cellular V2X based on LTE and/or 5G (New Radio) standards. Various aspects of the present disclosure may relate to New Radio (NR) cellular V2X networks, referred to herein as V2X networks, for simplicity. However, it should be understood that the concepts disclosed herein may not be limited to a particular V2X standard or may be directed to sidelink networks other than V2X networks.
In some aspects of the disclosure, the base station/scheduling entity and/or UE/scheduled entity may be configured for beamforming and/or multiple-input multiple-output (MIMO) technology.
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 300 is limited by the number of transmit or receive antennas 304 or 308, 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 the CSI-RS with separate C-RS sequences for each layer to provide for multi-layer channel estimation. From the CSI-RS, the UE may measure the channel quality across layers and resource blocks and feedback the CQI and RI values to the base station for use in updating the rank and assigning REs for future downlink transmissions.
In the simplest case, as shown in
Various aspects of the present disclosure will be described with reference to an OFDM waveform, schematically illustrated in
Within the present disclosure, a frame refers to a duration of 10 ms for wireless transmissions, with each frame consisting of 10 subframes of 1 ms each. On a given carrier, there may be one set of frames in the UL, and another set of frames in the DL. Referring now to
The resource grid 404 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 404 may be available for communication. The resource grid 404 is divided into multiple resource elements (REs) 406. 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) 408, which contains any suitable number of consecutive subcarriers (also referred to herein as or interlaces) 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 408 entirely corresponds to a single direction of communication (either transmission or reception for a given device).
A UE generally utilizes only a subset of the resource grid 404. 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 408 is shown as occupying less than the entire bandwidth of the subframe 402, with some subcarriers illustrated above and below the RB 408. In a given implementation, the subframe 402 may have a bandwidth corresponding to any number of one or more RBs 408. Further, in this illustration, the RB 408 is shown as occupying less than the entire duration of the subframe 402, although this is merely one possible example.
Each 1 ms subframe 402 may consist of one or multiple adjacent slots. In the example shown in
An expanded view of one of the slots 410 illustrates the slot 410 including a control region 412 and a data region 414. In general, the control region 412 may carry control channels (e.g., PDCCH), and the data region 414 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
In OFDM, to maintain orthogonality of the subcarriers or tones, the subcarrier spacing may be equal to the inverse of the symbol period. A numerology of an OFDM waveform refers to its particular subcarrier spacing and cyclic prefix (CP) overhead. A scalable numerology refers to the capability of the network to select different subcarrier spacings, and accordingly, with each spacing, to select the corresponding symbol duration, including the CP length. With a scalable numerology, a nominal subcarrier spacing (SCS) may be scaled upward or downward by integer multiples. In this manner, regardless of CP overhead and the selected SCS, symbol boundaries may be aligned at certain common multiples of symbols (e.g., aligned at the boundaries of each 1 ms subframe). The range of SCS may include any suitable SCS. For example, a scalable numerology may support a SCS ranging from 15 kHz to 480 kHz.
Although not illustrated in
In some examples, the slot 410 may be utilized for broadcast 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. 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 transmitting device (e.g., the base station 108) may allocate one or more REs 406 (e.g., within a control region 412) to carry DL control information 114 including one or more DL control channels that generally carry information originating from higher layers, such as a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), etc., to one or more UEs 106. In addition, DL REs may be allocated to carry DL physical signals that generally do not carry information originating from higher layers. These DL physical signals may include a primary synchronization signal (PSS); a secondary synchronization signal (SSS); demodulation reference signals (DM-RS); phase-tracking reference signals (PT-RS); channel-state information reference signals (CSI-RS); etc.
The synchronization signals PSS and SSS (collectively referred to as SS), and in some examples, the PBCH, may be transmitted in an SS block that includes 4 consecutive OFDM symbols, numbered via a time index in increasing order from 0 to 3. In the frequency domain, the SS block 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 SS block 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 nonconsecutive symbols for an SS block, within the scope of the present disclosure.
The PDCCH may carry downlink control information (DCI) for one or more UEs in a cell, including but not limited to power control commands, scheduling information, a grant, and/or an assignment of REs for DL and UL transmissions.
In an UL transmission, the transmitting device (e.g., the UE 106) may utilize one or more REs 406 to carry UL control information 118 originating from higher layers via one or more UL control channels, such as a physical uplink control channel (PUCCH), a physical random access channel (PRACH), etc., to the base station 108. Further, UL REs may carry UL physical signals that generally do not carry information originating from higher layers, such as demodulation reference signals (DM-RS), phase-tracking reference signals (PT-RS), sounding reference signals (SRS), etc. In some examples, the control information 118 may include a scheduling request (SR), i.e., a request for the base station 108 to schedule uplink transmissions. Here, in response to the SR transmitted on the control channel 118, the base station 108 may transmit downlink control information 114 that may schedule resources for uplink packet transmissions. UL control information may also include hybrid automatic repeat request (HARQ) feedback such as an acknowledgment (ACK) or negative acknowledgment (NACK), channel state information (CSI), or any other suitable UL control information. 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 addition to control information, one or more REs 406 (e.g., within the data region 414) 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 physical downlink shared channel (PDSCH); or for an UL transmission, a physical uplink shared channel (PUSCH).
In order for a UE to gain initial access to a cell, the RAN may provide system information (SI) characterizing the cell. This system information may be provided utilizing minimum system information (MSI), and other system information (OSI). The MSI may be periodically broadcast over the cell to provide the most basic information required for initial cell access, and for acquiring any OSI that may be broadcast periodically or sent on-demand. In some examples, the MSI may be provided over two different downlink channels. For example, the PBCH may carry a master information block (MIB), and the PDSCH may carry a system information block type 1 (SIB1). In the art, SIB1 may be referred to as the remaining minimum system information (RMSI).
OSI may include any SI that is not broadcast in the MSI. In some examples, the PDSCH may carry a plurality of SIBs, not limited to SIB1, discussed above. Here, the OSI may be provided in these SIBs, e.g., SIB2 and above.
In an example of sidelink communication over a sidelink carrier via a Proximity Service (ProSe) PC5 interface, the control region 312 of the slot 310 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 314 of the slot 310 may include a physical sidelink shared channel (PSSCH) including the data transmitted by the initiating (transmitting) sidelink device within resources reserved over the sidelink carrier by the transmitting sidelink device.
The channels or carriers described above and illustrated in
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.
When the traffic to be sent to a receiving UE arrives at a transmitting UE, a transmitting UE may first send the PSCCH, which conveys data including a part of sidelink control information (SCI) to be decoded by any UE for the channel sensing purpose, including the reserved time-frequency resources for transmissions, demodulation reference signal (DMRS) pattern and antenna port, etc. For the PSCCH, the SCI may be transmitted using quadrature phase shift keying (QPSK) with polar code. Another part of SCI may carry the remaining scheduling and control information to be decoded by the target receiving UE, and may share the associated PSSCH resources and the PSSCH DMRS with indications in the 1st-stage SCI for its resource allocation.
Similar to downlink transmissions in NR, in sidelink transmissions, primary and secondary synchronization signals (SPSS and SSSS, respectively) are supported, in which M-sequence and Gold sequence are used to generate the SPSS and SSSS, respectively. Through detecting the SPSS and SSSS, a UE is able to identify the sidelink synchronization identity (SSID) from the UE sending the SPSS/SSSS, where there may be, for example, 2 SPSS sequences and 336 SSSS sequences forming 672 SSIDs. Through detecting the SPSS/SSSS, a UE is therefore able to know the characteristics of the UE transmitting the SPSS/SSSS. A series of processes of acquiring timing and frequency synchronization together with SSIDs of UEs may be performed during initial cell search. In some examples, the UE sending the SPSS/SSSS may not be necessarily involved in sidelink transmissions, and a node (e.g., UE/eNB/gNB) sending the SPSS/SSSS may operate as a synchronization source.
The example of
In the example, automatic gain control (AGC) symbol 606 may be used to assist in regulating the signal strength at the input of the ADCs such that the required signal SNR for proper decoding is met. The PSCCH symbols 608 can occupy a number of consecutive RBs in the starting subchannel of the PSSCH transmission, e.g., over 2 or 3 symbols at the beginning of a slot, while the PSSCH 612, 616 may span over multiple subchannels, with associated DMRS symbols 610, 614, 618. In some examples, the last two symbols 622, excluding the gap (or guard period (GP)) 620, 624 are able to accommodate the PSFCH at every one, two, or four slots. Given a certain time-frequency location of the PSSCH, the candidate resources of the corresponding PSFCH should be identified first in order to identify the “actual” time-frequency location (resources) of the corresponding PSFCH.
For a PSSCH transmission, candidate resources of the corresponding PSFCH (720) may be configured as a set of RBs associated the starting subchannel and slot used for that PSSCH (718). Within the set of RBs configured for the actual PSFCH transmission, the first x number of RBs are associated with the first subchannel in the first slot associated with the PSFCH slot, the second x number of RBs are with the first subchannel in the second slot associated with the PSFCH slot, and so on, as illustrated in the figure. The frequency resources for the actual PSFCH transmission may be indicated by a bitmap for RBs in a resource (comb) pool. For each PSFCH, resources for ACK and NACK may be separated.
Transport channel & L1 signaling processing block 802 may be configured to perform code block segmentation and CRC attachment processing, as well as transport block CRC attachment processing. In addition, transport channel & L1 signaling processing block 804 may perform channel coding, rate matching and interleaving before forwarding a communication signal to physical channel processing block 806, which handles PSBCH, PSDCH, PSCCH and PSSCH processing. Physical channel processing block 806 may be configured to perform scrambling, modulation, transform precoding and mapping to physical resources, before the signal is handled by the physical signals generation and modulation block 808, which includes SL-DMRS, PSSS and SSSS signal processing, among others. The physical signals generation and modulation block 808 engages in demodulation of reference signals and processing of synchronization preambles in order to map symbols to physical resources and modulate the signals using, for example, single-carrier frequency division multiple access (SC-FDMA) before processing the signal for RF processing in block 812 and subsequent transmission in block 812.
Generally, timing synchronization and system information acquisition is facilitated by a broadcast transport channel, SL-BCH, and its physical counterpart, PSBCH. These channels may be considered similar to the BCH/PBCH broadcast channel used in LTE DL for cell and system acquisition support. The channels may be used for broadcasting a set of pre-ambles and basic system information within a certain region. A set of primary and secondary preambles, PSSS and SSSS, are used for synchronization purposes. The SL Master Information Block, MIB-SL carries the sidelink system information. Sidelink discovery may facilitated through a transport channel, SL-DCH and its physical counterpart, PSDCH. SL-DCH may follow the Downlink Shared Channel structure. In some examples, higher-layer specifications are absent in the discovery mode, since the announcement messages sent by UEs are PHY Transport Blocks formed with zero MAC overhead. Filling the TB payload may be left open and may depend on applications, such as proximity services (ProSe). Sidelink communication may be facilitated using a transport channel, SL-SCH, and its physical counterpart, PSSCH. In order for a receiving UE to successfully decode the physical communication channels, information regarding the specific resources assigned for transmission and the transmission configuration is needed, and are carried in the sidelink control channel, (SCI), which resembles a downlink DCI concept. The SCI may be carried in the PSCCH channel, and may be configured under SCI Format 0 and/or SCI Format 1. Physical channels estimation is enabled by SL demodulation reference signals (SL-DMRS). SL-DMRSs may be multiplexed with the payload of the PSBCH, PSDCH, PSCCH, and PSSCH. In some examples, two DMRS symbols may be used per subframe for PSBCH, PSDCH, PSCCH, PSSCH. In further examples, three DMRS symbols may be used for PSBCH, and four symbols for PSCCH and PSSCH.
Regarding sidelink communication, such as 3GPP Rel-16 NR V2X, channel state information (CSI-RS) is configured to be aperiodic and is included in PSSCH. Typically, only one resource element (RE) per resource block (RB) (density 1) is provided and only 1 or 2 ports are supported. For communication in the unlicensed spectrum or band (NR-U) (e.g., 5.125-7.125 GHz), interlace waveforms are defined to satisfy occupied channel bandwidth (OCB) requirements in the unlicensed band.
However, when PSSCH is configured to an interlaced waveform, specific challenges may arise regarding the transmission of CSI-RS, since, for example, in legacy systems (i.e., pre-3GPP Rel-16 NR), the CSI-RS waveforms may not match. Accordingly, there is a need to multiplex legacy SL CSI-RS waveforms with the PSSCH waveform. Interlaced CSI-RS waveforms have been difficult to incorporate into PSCCH, as they would add additional complexity to channel estimation. CSI-RS in sidelink is configured into a comb-like signal that occupies 1 or 2 contiguous REs per RB for 1 or 2 channel ports, respectively. Thus, for example, if one port is being used, CSI-RS occupies one RE per RB, and if two ports are being used, CSI-RS would occupy two contiguous REs per RB. For example, for 1 port CSI-RS, comb-like resource mapping in frequency domain without CDM may be used, where, for density of 1 or 0.5 REs/PRB, comb-12 may be used within a PRB while every other PRB may be mapped for density of 0.5 REs/PRB.
A UE may transmit sidelink CSI-RS within a PSSCH transmission, provided that CSI reporting is enabled by higher level parameter and a CSI request field in the corresponding SCI format is triggered or set (e.g., to “1”). Parameters for CSI-RS transmission may be configured via a higher layer parameter, for example, to indicate the number of ports for SL CSI-RS, the first OFDM symbol in a PRB used for SL CSI-RS and/or frequency domain allocation for SL CSI-RS.
In some examples, TDM for CSI-RS may be configured as the last symbol position in PSSCH. In the example of
In some cases, CSI-RS may not be triggered at all times. Accordingly, there may be instances where the last PSSCH symbol for CSI-RS does not necessarily need to be reserved. For example, a CSI request in SCI 0-2 (second stage SCI 0) may be made to indicate whether the last PSSCH/DMRS symbol should be dropped or not. IF CSI is triggered, CSI-RS may be mapped to the last symbol position of PSSCH and the last PSSCH/DMRS symbol is dropped. In some configurations, a DMRS is configured at the last symbol of PSSCH.
Alternately or in addition, PSSCH may be configured to always drop the last PSSCH/DMRS symbol regardless of a CSI request being set or not, and the CSI-RS may be mapped to the last symbol position. In some configurations, CSI requests may be configured in the second stage of SCI and DMRS channel estimation may be performed before decoding SCI 0-2. In this example, the CSI request may be used to dynamically control the mapping of the last symbol, which can advantageously reduce PSSCH demodulation complexity, and avoid potential collision with CSI-RS resource elements associated with other interlaces (e.g., 910, 920). In come configurations, the CSI request may be moved to SCI 0-1 and used to indicate whether or not the last PSSCH/DMRS is to be dropped or not. By moving the CSI request of PSCCH, the receiving UE may determine PSSCH and CSI-RS time allocation ahead of time and minimize PSSCH demodulation complications.
In some cases, a UE does not decode other UE's SCI before transmitting PSSCH and PSCCH, and thus may have no knowledge regarding whether CSI-RS associated with other interlaces is triggered or not. If CSI-RS is not triggered for a current interlace, instances where a CSI request in SCI 0-2 is used to indicate dropping the last PSSCH/DMRS or not as described above maximizes resource utilization by transmitting PSSCH/PSCCH in the potential CSI-RS symbol. Similarly, moving the CSI request to SCI 0-1 and using it to indicate whether or not to drop the last PSSCH/DMRS will have the same effect. However, there may be instances where a UE will need to handle CSI-RS from another UE that is present in the last PSSCH symbol when CSI-RS is not triggered.
In some examples, CSI-RS resource pool association may be performed on interlace resources (e.g., 910, 920) with PSSCH resources. As CSI-RS signals may be provided as comb-12 waveforms, 12 or 6 resources in the CSI-RS resource pool may be defined with 12 or 6 comb offsets. With a one port configuration, 12 comb offsets would be available, while for a two port configuration, 6 comb offsets would be available. Accordingly, each interlace may be associated with a CSI-RS comb offset. For example, the x-th resource in an interlace pool may be associated with CSI-RS, resulting in a comb offset number x.
The UE 1400 may be implemented with a processing system 1414 (or “processing apparatus”) that includes one or more processors 1404. Examples of processors 1404 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 UE 1400 may be configured to perform any one or more of the functions described herein, including, but not limited to, sidelink communication and processing. That is, the processor 1404, as utilized in the UE 1400, may be used to implement any one or more of the processes and procedures described herein.
In this example, the processing system 1414 may be implemented with a bus architecture, represented generally by the bus 1402. The bus 1402 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1414 and the overall design constraints. The bus 1402 communicatively couples together various circuits including one or more processors (represented generally by the processor 1404), a memory 805, and computer-readable media (represented generally by the computer-readable medium 1406). The bus 1402 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 1408 provides an interface between the bus 1402 and a transceiver 1410. The transceiver 1410 provides a communication interface or means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface 1412 (e.g., keypad, display, speaker, microphone, joystick) may also be provided. Of course, such a user interface 1412 is optional, and may be omitted in some examples, such as a base station.
In some aspects of the disclosure, the processor 1404 may include sidelink processing circuitry 1416 configured to implement, for example, communication and sidelink processing described herein, such as technologies and techniques described in
One or more processors 1404 in the processing system 1414 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 1406. The computer-readable medium 1406 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 1406 may reside in the processing system 1414, external to the processing system 1414, or distributed across multiple entities including the processing system 1414. The computer-readable medium 1406 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 1406 may include sidelink instructions 1422 configured for various functions, including, but not limited to, sidelink processing associated with functions of sidelink processor 1416. The computer-readable storage medium 1406 may also include time resource allocation instructions 1424 configured for various functions, including, but not limited to, time resource allocation associated with the functions of time resource allocation circuitry 1418. The computer-readable storage medium 1406 may also include collision handling instructions 1426 configured for various functions, including, but not limited to, collision handling functions associated with collision handling circuitry 1420.
Of course, in the above examples, the circuitry included in the processor 1414 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 1406, or any other suitable apparatus or means described in any one of the
Several aspects of a wireless communication network have been presented with reference to an exemplary 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
It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary 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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2020/087997 | 4/30/2020 | WO |
