Patent Application
20190341989
The present disclosure relates generally to communication systems, and more particularly, to wireless communication including beamforming.
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT)), and other requirements. Some aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. There exists a need for further improvements in 5G NR technology. For example, there is a need to improve the beamforming process in millimeter wave systems. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
In millimeter wave (mmW) systems, multiple antennas may be used at the base station and the user equipment (UE). The base station and the UE may perform a hierarchical beamforming process, for example, by using a beam refinement procedure, to find the finest and/or narrowest beam at the base station side and the UE side for beamformed communication. However, there may be situations in which a completion of such a beam refinement procedure might not be helpful in terms of additional accrued gains relative to the costs incurred, and may instead waste power and wireless resources. The present application provides a solution that enables efficient use of power and wireless resources by determining when it may be advantageous to perform an early stop to a beam refinement procedure. Aspects presented herein enable a base station to identify such situations when it may be advantageous to perform an early stop, such as when the base station side angular spread is small, when the Doppler related fading is large across paths, and/or when the beam switching rate at the UE side is slow. Aspects may include feedback techniques for the UE to indicate the UE capability information to the base station, and sounding methods for the base station to determine the angular spread. With such information, the base station may determine if and/or when to stop the beam refinement procedure.
In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a UE. The apparatus receives a signal over a plurality of beams from a base station in a beam refinement procedure during a hierarchical beamforming process. The apparatus transmits an indication to the base station, where the indication may be configured to assist the base station to determine whether to perform an early stop to the beam refinement procedure prior to a completion of the beam refinement procedure.
In another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a base station. The apparatus receives from a UE a plurality of signals on a beam. The apparatus determines an angular spread at the base station based on the plurality of signals from the UE.
In yet another aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided for wireless communication at a base station. The apparatus transmits at least one signal over a plurality of beams in a beam refinement procedure with a UE. The apparatus further receives an indication from the UE. The apparatus determines whether to stop the beam refinement procedure prior to a completion of the beam refinement procedure based, at least in part, on the indication received from the UE.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.
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.
Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.
By way of example, an element, or any portion of an element, or any combination of elements may be implemented as a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems on a chip (SoC), baseband processors, 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. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, 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.
Accordingly, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. Storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the aforementioned types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.
The base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface with the EPC 160 through backhaul links 132 (e.g., S1 interface). The base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) may interface with 5GC 190 through backhaul links 184. In addition to other functions, the base stations 102 may perform one or more of the following functions: transfer of user data, radio channel ciphering and deciphering, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations 102 may communicate directly or indirectly (e.g., through the EPC 160 or 5GC 190) with each other over backhaul links 134 (e.g., X2 interface). The backhaul links 134 may be wired or wireless.
The base stations 102 may wirelessly communicate with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102′ may have a coverage area 110′ that overlaps the coverage area 110 of one or more macro base stations 102. A network that includes both small cell and macro cells may be known as a heterogeneous network. A heterogeneous network may also include Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communication links 120 between the base stations 102 and the UEs 104 may include uplink (UL) (also referred to as reverse link) transmissions from a UE 104 to a base station 102 and/or downlink (DL) (also referred to as forward link) transmissions from a base station 102 to a UE 104. The communication links 120 may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be through one or more carriers. The base stations 102/UEs 104 may use spectrum up to YMHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction. The carriers may or may not be adjacent to each other. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL). The component carriers may include a primary component carrier and one or more secondary component carriers. A primary component carrier may be referred to as a primary cell (PCell) and a secondary component carrier may be referred to as a secondary cell (SCell).
Certain UEs 104 may communicate with each other using device-to-device (D2D) communication link 158. The D2D communication link 158 may use the DL/UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communication may be through a variety of wireless D2D communications systems, such as for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.
The wireless communications system may further include a Wi-Fi access point (AP) 150 in communication with Wi-Fi stations (STAs) 152 via communication links 154 in a 5 GHz unlicensed frequency spectrum. When communicating in an unlicensed frequency spectrum, the STAs 152/AP 150 may perform a clear channel assessment (CCA) prior to communicating in order to determine whether the channel is available.
The small cell 102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell 102′ may employ NR and use the same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP 150. The small cell 102′, employing NR in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. A base station 102, whether a small cell 102′ or a large cell (e.g., macro base station), may include an eNB, gNodeB (gNB), or other type of base station. Some base stations, such as gNB 180 may operate in a traditional sub-6 GHz spectrum, in millimeter wave (mmW) frequencies, and/or near mmW frequencies in communication with the UE 104. When the gNB 180 operates in mmW or near mmW frequencies, the gNB 180 may be referred to as an mmW base station. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in the band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz) has extremely high path loss and a short range. The mmW base station 180 may utilize beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.
The base station 180 may transmit a beamformed signal to the UE 104 in one or more transmit directions 182′. The UE 104 may receive the beamformed signal from the base station 180 in one or more receive directions 182″. The UE 104 may also transmit a beamformed signal to the base station 180 in one or more transmit directions. The base station 180 may receive the beamformed signal from the UE 104 in one or more receive directions. The base station 180/UE 104 may perform beam training to determine the best receive and transmit directions for each of the base station 180/UE 104. The transmit and receive directions for the base station 180 may or may not be the same. The transmit and receive directions for the UE 104 may or may not be the same.
The EPC 160 may include a Mobility Management Entity (MME) 162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172. The MME 162 may be in communication with a Home Subscriber Server (HSS) 174. The MME 162 is the control node that processes the signaling between the UEs 104 and the EPC 160. Generally, the MME 162 provides bearer and connection management. All user Internet protocol (IP) packets are transferred through the Serving Gateway 166, which itself is connected to the PDN Gateway 172. The PDN Gateway 172 provides UE IP address allocation as well as other functions. The PDN Gateway 172 and the BM-SC 170 are connected to the IP Services 176. The IP Services 176 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services. The BM-SC 170 may provide functions for MBMS user service provisioning and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS Bearer Services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS Gateway 168 may be used to distribute MBMS traffic to the base stations 102 belonging to a Multicast Broadcast Single Frequency Network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.
The 5GC 190 may include a Access and Mobility Management Function (AMF) 192, other AMFs 193, a Session Management Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF 192 may be in communication with a Unified Data Management (UDM) 196. The AMF 192 is the control node that processes the signaling between the UEs 104 and the 5GC 190. Generally, the AMF 192 provides QoS flow and session management. All user Internet protocol (IP) packets are transferred through the UPF 195. The UPF 195 provides UE IP address allocation as well as other functions. The UPF 195 is connected to the IP Services 197. The IP Services 197 may include the Internet, an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming Service, and/or other IP services.
The base station may also be referred to as a gNB, Node B, evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. The base station 102 provides an access point to the EPC 160 or 5GC 190 for a UE 104. Examples of UEs 104 include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor/actuator, a display, or any other similar functioning device. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meter, gas pump, toaster, vehicles, heart monitor, etc.). The UE 104 may also be referred to as a station, a mobile station, 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, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.
Referring again to
Other wireless communication technologies may have a different frame structure and/or different channels. A frame (10 ms) may be divided into 10 equally sized subframes (1 ms). Each subframe may include one or more time slots. Subframes may also include mini-slots, which may include 7, 4, or 2 symbols. Each slot may include 7 or 14 symbols, depending on the slot configuration. For slot configuration 0, each slot may include 14 symbols, and for slot configuration 1, each slot may include 7 symbols. The symbols on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission). The number of slots within a subframe is based on the slot configuration and the numerology. For slot configuration 0, different numerologies μ 0 to 5 allow for 1, 2, 4, 8, 16, and 32 slots, respectively, per subframe. For slot configuration 1, different numerologies 0 to 2 allow for 2, 4, and 8 slots, respectively, per subframe. Accordingly, for slot configuration 0 and numerology μ, there are 14 symbols/slot and 2μ slots/subframe. The subcarrier spacing and symbol length/duration are a function of the numerology. The subcarrier spacing may be equal to 2μ*15 kKz, where μ is the numerology 0 to 5. As such, the numerology μ=0 has a subcarrier spacing of 15 kHz and the numerology μ=5 has a subcarrier spacing of 480 kHz. The symbol length/duration is inversely related to the subcarrier spacing.
A resource grid may be used to represent the frame structure. Each time slot includes a resource block (RB) (also referred to as physical RBs (PRBs)) that extends 12 consecutive subcarriers. The resource grid is divided into multiple resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.
As illustrated in
As illustrated in
The transmit (TX) processor 316 and the receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.
At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to the receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined by the RX processor 356 into a single OFDM symbol stream. The RX processor 356 then converts the OFDM symbol stream from the time-domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station 310. These soft decisions may be based on channel estimates computed by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals that were originally transmitted by the base station 310 on the physical channel. The data and control signals are then provided to the controller/processor 359, which implements layer 3 and layer 2 functionality.
The controller/processor 359 can be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer-readable medium. In the UL, the controller/processor 359 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller/processor 359 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.
Similar to the functionality described in connection with the DL transmission by the base station 310, the controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.
Channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the base station 310 may be used by the TX processor 368 to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antenna 352 via separate transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.
The UL transmission is processed at the base station 310 in a manner similar to that described in connection with the receiver function at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.
The controller/processor 375 can be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer-readable medium. In the UL, the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350. IP packets from the controller/processor 375 may be provided to the EPC 160. The controller/processor 375 is also responsible for error detection using an ACK and/or NACK protocol to support HARQ operations.
There may be tradeoffs in the hierarchical beamforming process at the base station 502 and the UE 504. For example, there may be tradeoff between an initial link establishment time or beam acquisition latency and a peak SNR. The completion of the beam refinement procedure may find the finest and narrowest beams with the highest peak SNR at certain level in the hierarchy (e.g., Level 3), but at a cost of a higher initial link establishment time or a longer beam refinement latency than that of the beams at Level 2. As another example, there may also be tradeoff between robustness to blockage/Doppler with wider beams and a peak SNR. The finest and narrowest beams at Level 3 may have the highest peak SNR, but may have less robustness to blockage/Doppler than the wider beams at Level 2. In order to balance the need to reduce the beam refinement latency and the need for signal reliability, an early stop/stoppage of the beam refinement procedure may be performed, as presented herein.
Multiple paths/clusters within this angular spread 608 can undergo independent Doppler fading, especially if a bandwidth allocation is high (e.g., greater than 100 MHz). The base station 602 can switch from a best path/cluster to another best path/cluster using a Level 3 beam (e.g., due to such fading), only when the base station 602 is able to scan its Level 3 beams fast enough. Additionally, the UE 604 should be able to scan its best beams quickly enough for the base station 602 to perform the switch.
Fast beam switching capability at the base station 602 is typically possible, because the base station 602 is a network resource. However, fast beam switching capability at the UE 604 may require very complex hardware and may consume significant power. The beam switching capability of the UE 604 may be limited due to measurement and reporting signaling overhead or latency. For example, multiple measurement period configurations may be enabled, and a base station may select a preferred measurement period from among the configurations. As another example, if there is a UL/DL reciprocity mismatch (e.g., due to poor calibration, circuit mismatches, etc.), then the UE 604 may have to measure CSI-RS, and send a feedback signal instead of relying on secondary synchronization block signals (SSB). The CSI-RS measurements may limit the switching capability of the UE 604. A UE 604 may or may not have a fast switching capability. For example, a premium tier UE may have the fast switching capability, but a lower tier UE might not have the fast switching capability. When the UE has limitations on its beam switching capability, it may be better for the base station to stop a beam refinement procedure early, e.g. at a Level 2 stage.
For example, in the situations when the base station 602 has a narrow angular spread, and the UE 604 does not have the fast beam switching capability, it is advantageous to stop the beam refinement procedure early, for example, at Level 2. In order for the base station 602 to perform an early stop of the beam refinement procedure, the base station 602 may need to determine the angular spread at the base station 602, and the beam switching capability of the UE 604.
The UE 704 may transmit an indication 705 of a beam switching capability or a hardware capability of the UE 704. In some aspects, the indication 705 may include information capturing a time that the UE 704 uses to scan through the plurality of beams from the base station 702. The plurality of beams may be scanned at a pseudo-omni level or a directional beam level at the UE 704 side, as the UE 704 determines. For example, the time may be based on a scan of the plurality of beams at the pseudo-omni beam level. For another example, the time may be based on a scan of the plurality of beams at the directional beam level. In some aspects, the indication 705 may include a number of beams on which the time is based. The number of beams scanned at the UE 704 may be UE-specific, and/or time-varying. For example, the number of beams the UE 704 considers in determining the beam switching rate may be time-varying.
In some aspects, the time in the indication 705 may be based on hardware related factors, including contributions from an antenna weight settling down latency, circuit related latencies, for example, a radio frequency circuit related latency, etc.
In some aspects, the UE 704 may scan through the plurality of beams slowly to save power. The UE may incorporate this power saving constraint in the feedback indication 705. For example, the time for the UE 704 to scan through the plurality of beams may be based on a power saving constraint at the UE 704, and the indication 705 may further indicate the power saving constraint. In some aspects, the indication 705 may further indicate a power consumption. For example, the UE 704 may feed back a rate of beam switching and the power consumption in the scanning process. In some aspects, an absence of a power consumption may indicate a nominal power consumption that is configured by the base station 702. If the UE 704 feeds back no power value, it may be taken by the base station 702 to indicate a nominal power consumption. In some aspects, the indication 705 may be associated with a quantized value. The set of quantized values may be configured by the base station 702. For example, the indication 705 may be quantized with quantization settings/meanings, which may be configured by the base station 702.
The UE 704 may transmit an indication 706 of mobility information for the UE 704 or Doppler estimate information for the UE 704. In some aspects, the mobility information or the Doppler estimate information for the UE 704 may be based on a plurality of measurements at a plurality of sensors at the UE 704. For example, the plurality of sensors may include one or more of an accelerometer, a gyroscope, and a tachometer.
The base station 702 may use the feedback 705, 706 from the UE in combination with other information to determine whether to continue or to stop the beam refinement procedure.
As a first example, the base station 702 may further base the determination on an amount of data, or a payload, to be conveyed from the base station 702 to the UE 704.
As a second example, the base station 702 may further base the determination on a number of Component Carriers (CCs) allocated to the UE 704. If the UE 704 requests a small number of CCs due to power consumption related issues, then the base station 702 may determine that a Level 3 beam may be better suited for communication with the UE, because the Level 3 beam may suffer less from Doppler fading. In contrast, when the UE 704 requests a large number or CCs, or when the base station 702 allocates a large number of CCs to the UE, the higher number of CCs indicates a higher payload. The base station 702 may determine that Level 2 beam may be a more robust choice from a Doppler perspective, which may guide the determination regarding whether to continue or stop the beam refinement procedure.
As a third example, the base station 702 may further base the determination on the angular spread seen at the base station. There may be several ways for the base station 702 to determine or estimate the angular spread. For example, the base station 702 may run through each of the Level 2 beams and the Level 3 beams in a beam refinement procedure and wait for the UE 704 to feed back a Reference Signal Received Power (RSRP) at every stage. With this information, the base station 702 may decide to go back to one of the Level 2 beams. However, this would require the base station to perform the Level 3 refinement procedure before determining to return to the Level 2 beam, wasting system resources, such as time, increasing power consumption at the UE 704, increasing the feedback overhead, etc.
The UE 704 may transmit a plurality of training signals 707 to the base station 702. The base station 702 may determine an angular spread at the base station 702 based on the plurality of training signals 707 from the UE 704, at 706. In some aspects, the base station 702 may estimate an RSRP based on the plurality of training signals 707. For example, the RSRP may be estimated for a set of beams having an adjacent or partially overlapping spatial or angular orientation. The angular spread may be determined based on a variation in the estimated RSRP for the set of beams. For example, the UE 704 may use a plurality of sounding reference signals (SRSs) as the plurality of training signals 707. The plurality of SRSs may be transmitted over multiple symbols or sub-symbols on a single best beam. The base station 702 may try out a set of beams, which are next to each other in terms of spatial/directional orientation, and estimate the RSRP. From the RSRP spread/variation, the angular spread at the base station 702 may be determined. There may be a cost in terms of system resources when using the SRSs. Thus, the UE 704 may limit use of the SRSs to once in a time period. The time period may be configured by the base station 702 to maintain system efficiency. The UE 704 may also use the SRSs in a semi-persistent manner. The angular spread at the base station 702 side might not be changed by an UL/DL reciprocity mismatch. In such a scenario of UL/DL reciprocity mismatches, the base station 702 may still use CSI-RS for beam training.
The base station 702 may determine whether to stop the beam refinement procedure prior to a completion of the beam refinement procedure based, at least in part, on the indication (e.g., 705, 706, 707) received from the UE 704, at 710. The base station 702 may determine the angular spread at its end by using the plurality of training signals 707 from the UE 704, as indicated at 708. The base station 702 may incorporate the feedback from the UE 704 with other information of the base station 702 and the angular spread at the base station 702, to make a determination to stop the beam refinement procedure prior to the completion of the beam refinement procedure. The feedback from the UE 704 may include any of the indication 705 of the beam switching capability, the indication 706 of the mobility or Doppler estimate information of the UE 704, and/or the training signals 707.
At 804, the UE receives at least one signal over a plurality of beams from a base station in a beam refinement procedure during a hierarchical beamforming process. There are situations where a completion of the beam refinement procedure may not be helpful. It may be advantageous to perform an early stop to the beam refinement procedure.
At 806, the UE transmits an indication to the base station. The indication may be configured to assist the base station to determine whether to perform the early stop to the beam refinement procedure, e.g., prior to a completion of the beam refinement procedure. For example, the information may assist the base station to determine to stop beam refinement at a Level 2 stage, e.g., an intermediate beam stage.
In some aspects, the indication may indicate the beam switching capability 808 of the UE, e.g., as described in connection with 705 in
For another example, the time may be based on a power saving constraint at the UE, and where the indication further indicates the power saving constraint. The UE may scan through the beams from the base station slowly in order to save power, and the UE may indicate information regarding this power saving constraint to the base station. For example, the indication may further indicate a power consumption, e.g., related to a beam scanning process. For example, an absence of a power consumption may indicate a nominal power consumption that is configured by the base station.
The indication transmitted by the UE may be associated with a quantized value. The quantized value, meaning, setting, etc. may be configured by the base station.
In some aspects, the indication may indicate mobility information 810 for the UE or Doppler estimate information for the UE, e.g., as described in connection with 706 in
In some aspects, the indication may comprise a plurality of training signals 812 on a selected beam, e.g., as described in connection with 707 in
In some aspects, the apparatus 904 may include a beam switching capability component 908. The beam switching capability component 908 may be configured to indicate a beam switching rate for the UE, as described in connection with 808 in
The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of
The processing system 1014 may be coupled to a transceiver 1010. The transceiver 1010 is coupled to one or more antennas 1020. The transceiver 1010 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1010 receives a signal from the one or more antennas 1020, extracts information from the received signal, and provides the extracted information to the processing system 1014, specifically the reception component 903. In addition, the transceiver 1010 receives information from the processing system 1014, specifically the transmission component 906, and based on the received information, generates a signal to be applied to the one or more antennas 1020. The processing system 1014 includes a processor 1004 coupled to a computer-readable medium/memory 1006. The processor 1004 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1006. The software, when executed by the processor 1004, causes the processing system 1014 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1006 may also be used for storing data that is manipulated by the processor 1004 when executing software. The processing system 1014 further includes at least one of the components 904, 906, 908, 910, 912. The components may be software components running in the processor 1004, resident/stored in the computer readable medium/memory 1006, one or more hardware components coupled to the processor 1004, or some combination thereof. The processing system 1014 may be a component of the UE 350 and may include the memory 360 and/or at least one of the TX processor 368, the RX processor 356, and the controller/processor 359.
In one configuration, the apparatus 904/904′ for wireless communication includes means for receiving a signal over a plurality of beams from a base station in a beam refinement procedure during a hierarchical beamforming process, and means for transmitting an indication to the base station, where the indication may be configured to assist the base station to determine whether to perform an early stop to the beam refinement procedure prior to a completion of the beam refinement procedure. The aforementioned means may be one or more of the aforementioned components of the apparatus 904 and/or the processing system 1014 of the apparatus 904′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1014 may include the TX Processor 368, the RX Processor 356, and the controller/processor 359. As such, in one configuration, the aforementioned means may be the TX Processor 368, the RX Processor 356, and the controller/processor 359 configured to perform the functions recited by the aforementioned means.
At 1102, the base station transmits at least one signal over a plurality of beams in a beam refinement procedure to the UE, for example, in a hierarchical beamforming process. The base station may be configured to perform an early stop/stoppage of the beam refinement procedure in situations where a completion of the beam refinement procedure may not be helpful.
At 1104, the base station receives an indication from the UE. In some aspects, the indication may indicate the beam switching capability of the UE, as described in connection with 705 in
At 1106, the base station may receive a plurality of signals on a selected beam from the UE, as described in connection with 707 in
At 1108, the base station may estimate a RSRP for a set of beams having an adjacent or partially overlapping spatial or angular orientation.
At 1110, the base stations determines the angular spread at the base station side, as described in connection with 708 in
At 1112, the base station determines whether to stop the beam refinement procedure prior to a completion of the beam refinement procedure based, at least in part, on the indication received from the UE, as described in connection with 710 in
At 1406, the base station may receive a plurality of signals on a selected beam from the UE. For example, the plurality of training signals may comprise a plurality of training signals. In one example, the plurality of signals may comprise a plurality of sounding reference signals (SRSs). The plurality of signals may be transmitted over a plurality of symbols or over a plurality of sub-symbols.
At 1410, the base stations determines the angular spread at the base station side, as described in connection with 708 in
Thus, at 1408, the base station may also estimate an RSRP based on the plurality of signals received at 1406. The RSRP may be estimated for a set of beams having an adjacent or partially overlapping spatial or angular orientation.
In some aspects, the apparatus 1202 may include a beam switching capability component 1208. The beam switching capability component 1208 may be configured to receive an indication of a beam switching rate of the UE 1204, as described in connection with 1104. In some aspects, the apparatus 1202 may include a mobility information or Doppler estimate information component 1210, configured to receive an indication of the mobility information or the Doppler estimate information of the UE 1204, as described in connection with 1104. In some aspects, the apparatus 1202 may include a training signal component 1212. The plurality of training signals component 1212 may be configured to receive a plurality of training signals, for example, a plurality of sounding reference signals (SRSs) from the UE 1204, as described in connection with 1108, 1408.
In some aspects, the apparatus 1202 may include a determination component for an angular spread 1216 at the base station side. For example, the plurality of training signals component 1212 may be configured to receive the plurality of training signals on the selected beam from the UE 1204. For example, the plurality of training signals may comprise the plurality of sounding reference signals (SRSs). The plurality of training signals may be transmitted over a plurality of symbols or over a plurality of sub-symbols. The apparatus 1202 may further include a RSRP component configured to estimate a RSRP for a set of beams having an adjacent or partially overlapping spatial or angular orientation.
The determination component 1218 is configured to make a determination of whether to perform an early stop/stoppage based on, at least in part, the information from the beam switching component 1208, and/or the information from the mobility/Doppler information component 1210, and/or the information from the angular spread determination component 1216.
The apparatus may include additional components that perform each of the blocks of the algorithm in the aforementioned flowcharts of
The processing system 1314 may be coupled to a transceiver 1310. The transceiver 1310 is coupled to one or more antennas 1320. The transceiver 1310 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1310 receives a signal from the one or more antennas 1320, extracts information from the received signal, and provides the extracted information to the processing system 1314, specifically the reception component 1203. In addition, the transceiver 1310 receives information from the processing system 1314, specifically the transmission component 1206, and based on the received information, generates a signal to be applied to the one or more antennas 1320. The processing system 1314 includes a processor 1304 coupled to a computer-readable medium/memory 1306. The processor 1304 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1306. The software, when executed by the processor 1304, causes the processing system 1314 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1306 may also be used for storing data that is manipulated by the processor 1304 when executing software. The processing system 1314 further includes at least one of the components 1204, 1206, 1208, 1210, 1212, 1214, 1216, 1218. The components may be software components running in the processor 1304, resident/stored in the computer readable medium/memory 1306, one or more hardware components coupled to the processor 1304, or some combination thereof. The processing system 1314 may be a component of the base station 310 and may include the memory 376 and/or at least one of the TX processor 316, the RX processor 370, and the controller/processor 375.
In one configuration, the apparatus 1202/1202′ for wireless communication includes means for transmitting a signal over a plurality of beams in a beam refinement procedure with a UE; means for determining an angular spread at the base station based on the plurality of training signals from the UE; means for estimating an RSRP; means for beginning a beam refinement procedure with a UE; means for receiving an indication from the UE; and means for determining whether to stop the beam refinement procedure prior to a completion of the beam refinement procedure based, at least in part, on the indication received from the UE. The aforementioned means may be one or more of the aforementioned components of the apparatus 1202 and/or the processing system 1314 of the apparatus 1202′ configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1314 may include the TX Processor 316, the RX Processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX Processor 316, the RX Processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.
It is understood that the specific order or hierarchy of blocks in the processes/flowcharts disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of blocks in the processes/flowcharts may be rearranged. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.
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 is to be accorded the full scope consistent with the language 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.” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or 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. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
This application claims the benefit of U.S. Provisional Application Ser. No. 62/667,372, entitled “METHODS FOR EARLY STOPPAGE OF BEAM REFINEMENT IN MILLIMETER WAVE SYSTEMS” and filed on May 4, 2018, the disclosure of which is expressly incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62667372 | May 2018 | US |
