Method and apparatus for estimating channel state information in advanced MIMO antenna system for cellular communication

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting a high data rate beyond a 4G communication system such as Long Term Evolution (LTE). Methods and apparatus for estimating channel state information in an advanced multiple-input multiple-output (MIMO) antenna system for cellular communications. A method of operating a base station (BS) includes generating first configuration information including a set of sounding reference signal (SRS) resources, each SRS resource in the set of SRS resources being associated with a sounding reference signal (SRS)-pathloss reference signal; transmitting the first configuration information to a user equipment (UE); receiving the SRS based on the first configuration information; selecting a subset of the set of SRS resources based on the SRS and the first configuration information; and generating second configuration information comprising a subset of the set of SRS resources.

Description

Technical Field

[0001] The present disclosure relates generally to wireless communication systems, and more particularly, to estimating channel state information in advanced multiple-input multiple-output (MIMO) antenna systems for cellular communications. Background Art

[0002] Considering the development of wireless communication from generation to generation, technology is mainly developed for services for humans (such as voice calls, multimedia services and data services). After the commercialization of 5G (fifth generation) communication systems, it is expected that the number of connected devices will grow exponentially. These devices will be increasingly connected to communication networks. Examples of connected things can include vehicles, robots, drones, household appliances, displays, smart sensors connected to various infrastructures, construction machines and factory equipment. Mobile devices are expected to evolve in various form factors, such as augmented reality glasses, virtual reality head-mounted devices (headset) and holographic devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (sixth generation) era, efforts have been made to develop improved 6G communication systems. For these reasons, 6G communication systems are called super 5G systems.

[0003] The 6G communication system, which is expected to be commercialized around 2030, will have a peak data rate of tera (1000 giga) bps and a radio latency of less than 100 μsec, and will therefore be 50 times faster than the 5G communication system and have a radio latency of 1 / 10 of that of the 5G communication system.

[0004] In order to achieve such high data rates and ultra-low latency, it has been considered to implement 6G communication systems in the terahertz band (e.g., 95GHz to 3THz band). It is expected that since the path loss and atmospheric absorption in the terahertz band are more serious than those in the millimeter wave (mmWave) band introduced in 5G, the technology that can ensure the signal transmission distance (i.e., coverage) will become more critical. As the main technology for ensuring coverage, it is necessary to develop radio frequency (RF) elements, antennas, new waveforms with better coverage than orthogonal frequency division multiplexing (OFDM), beamforming and large-scale multiple input multiple output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas and multi-antenna transmission technologies such as large-scale antennas. In addition, new technologies for improving the coverage of terahertz band signals have been discussed, such as lenses and antennas based on metamaterials, orbital angular momentum (OAM) and reconfigurable smart surfaces (RIS).

[0005] In addition, in order to improve spectrum efficiency and overall network performance, the following technologies have been developed for 6G communication systems: full-duplex technology for enabling uplink transmission and downlink transmission to use the same frequency resources at the same time; network technology for utilizing satellites, high-altitude platform stations (HAPS), etc. in an integrated manner; improved network structure for supporting mobile base stations, etc. and realizing network operation optimization and automation, etc.; dynamic spectrum sharing technology via conflict avoidance based on predicted spectrum use; use of artificial intelligence (AI) in wireless communication for improving overall network operation by utilizing AI from the design stage of developing 6G and internalizing end-to-end AI support functions; and next-generation distributed computing technology for overcoming the limitations of UE computing power through ultra-high performance communication and computing resources (such as mobile edge computing (MEC), cloud, etc.) accessible on the network. In addition, attempts are continuing to strengthen connections between devices, optimize networks, promote softwareization of network entities, and increase the openness of wireless communications by designing new protocols to be used in 6G communication systems, developing mechanisms for realizing hardware-based security environments and secure use of data, and developing technologies for maintaining privacy.

[0006] It is expected that research and development of 6G communication systems in terms of hyperconnectivity, including human-to-machine (P2M) and machine-to-machine (M2M), will allow the next hyperconnected experience. In particular, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital copies can be provided through 6G communication systems. In addition, services such as remote surgery for safety and reliability enhancement, industrial automation, and emergency response will be provided through 6G communication systems, so that these technologies can be applied to various fields such as industry, healthcare, automobiles, and home appliances.

[0007] Fifth generation (5G) or New Radio (NR) mobile communications have been gathering more and more momentum recently with all the global technical activities for various candidate technologies from industry and academia. Candidate enablers for 5G / NR mobile communications include massive antenna technologies from traditional cellular frequency bands to high frequencies to provide beamforming gain and support increased capacity, new waveforms (e.g., new radio access technologies (RATs)) to flexibly accommodate various services / applications with different requirements, new multiple access schemes to support massive connections, etc. Summary of the invention

[0008] Technical issues

[0009] The baseband processing unit of the BS requires per-user CSI for single-user and multi-user MIMO beamforming and scheduling. Here, the CSI of user i includes at least the channel vector h i , channel vector h iIncludes N for each resource element T entries. Length - N T The channel vector h i It can be represented by two components, length N D The digital channel vector and length N A N on the subarray D Channel vector The set of d=1,...,N D , according to the following formula:

[0010] In the general formula for this subarray with different simulated beams, the DU needs to estimate N T =N D ·N A entries, which can be as large as 2048 or even more, which requires large SRS resource overhead and computational complexity.

[0011] Therefore, low-complexity high-precision channel vector / matrix estimation for antenna panels with a very large number of antennas is crucial to achieve extreme MIMO performance gains.

[0012] Solution to the problem

[0013] The present disclosure relates to wireless communication systems, and more particularly, to supporting estimation of channel state information in advanced MIMO antenna systems for cellular communications.

[0014] In one embodiment, a base station (BS) is provided. The BS includes a processor configured to generate first configuration information including a sounding reference signal (SRS) resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal. The BS also includes a transceiver operably coupled to the processor, the transceiver configured to: send the first configuration information to a user equipment (UE), and receive the SRS based on the first configuration information. The processor of the BS is also configured to select a subset of the SRS resource set based on the SRS and the first configuration information, and to generate second configuration information including the subset of the SRS resource set.

[0015] In another embodiment, a method of a BS is provided. The method includes: generating first configuration information including an SRS resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal; sending the first configuration information to a UE; receiving an SRS based on the first configuration information; selecting a subset of the SRS resource set based on the SRS and the first configuration information; and generating second configuration information including the subset of the SRS resource set.

[0016] In yet another embodiment, a UE is provided. The UE includes a transceiver configured to receive first configuration information from a BS. The UE also includes a processor operably coupled to the transceiver, the processor configured to identify first configuration information including a set of SRS resources, each SRS resource in the set of SRS resources being associated with an SRS-path loss reference signal for transmitting an SRS. The transceiver of the UE is further configured to transmit an SRS to the BS based on the first configuration information, a subset of the set of SRS resources being selected based on the SRS and the first configuration information, and second configuration information including a subset of the set of SRS resources being identified based on the subset of the set of SRS resources.

[0017] Other technical features may be apparent to those skilled in the art from the following drawings, descriptions and claims.

[0018] Beneficial Effects of the Invention

[0019] The present disclosure provides a base station that uses a per-subarray hybrid analog-digital beamforming architecture to estimate channel state information using a sounding reference signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals represent like parts:

[0021] Figure 1 An example of a wireless network according to an embodiment of the present disclosure is shown;

[0022] Figure 2 An example of a gNB according to an embodiment of the present disclosure is shown;

[0023] Figure 3 An example of a UE according to an embodiment of the present disclosure is shown;

[0024] Figure 4 and Figure 5 shows examples of wireless transmit and receive paths according to the present disclosure;

[0025] Figure 6 An example of an antenna structure according to an embodiment of the present disclosure is shown;

[0026] Figure 7 An example of an antenna panel including NT antenna elements according to an embodiment of the present disclosure is shown;

[0027] Figure 8 An example of an RF front-end and baseband implementation of a base station according to an embodiment of the present disclosure is shown;

[0028] Fig. 9 shows an example of a signal processing module chain according to an embodiment of the present disclosure;

[0029] Fig.10 An example of SRS reception and processing according to an embodiment of the present disclosure is shown;

[0030] Fig.11 An example of MIMO channel estimation according to an embodiment of the present disclosure is shown;

[0031] Fig.12 The method for obtaining each subcarrier N according to an embodiment of the present disclosure is shown. D A flowchart of a BS method for measuring a SRS channel;

[0032] Fig.13 A flow chart of a BS method for reconstructing a channel matrix according to an embodiment of the present disclosure is shown;

[0033] Fig.14 A flowchart of a BS method for a subset of SRS simulated beams according to an embodiment of the present disclosure is shown;

[0034] Fig.15a A flowchart of a BS method for configuring multiple SRS resources according to an embodiment of the present disclosure is shown;

[0035] Fig.15b A flowchart of a UE method for configuring multiple SRS resources according to an embodiment of the present disclosure is shown;

[0036] Fig.16a A flowchart of a BS method for notifying downward selection of SRS resources according to an embodiment of the present disclosure is shown;

[0037] Fig.16b A flowchart of a method for notifying a UE of a downward selection of SRS resources according to an embodiment of the present disclosure is shown;

[0038] Fig.17 A flowchart of a BS method for two SRS resource set configuration and management according to an embodiment of the present disclosure is shown; and

[0039] Fig.18 A flowchart of a BS method for estimating channel state information according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0040] Before the following detailed description, it may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document. The term "coupling" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not these elements are in physical contact with each other. The terms "send", "receive", "communication" and their derivatives cover both direct and indirect communication. The terms "include" and "comprise" and their derivatives refer to including but not limited to. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives mean including, included in, interconnected with, included in, included in, connected to, or connected with, coupled to, or coupled with, can communicate with, collaborate with, interweave, juxtapose, be close to, bound to, or bound with, have, have the property of, have a relationship with, or have a relationship with. The term "controller" means any device, system, or part thereof that controls at least one operation. Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware. The functions associated with any particular controller can be centralized or distributed, whether local or remote. The phrase "at least one of" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one of the items in the list may be required. For example, at least one of A, B, and C includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.

[0041] In addition, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by a computer-readable program code and embodied in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, processes, functions, objects, classes, instances, related data or parts thereof suitable for implementation in a suitable computer-readable program code. The phrase "computer-readable program code" includes any type of computer code, including source code, object code and executable code. The phrase "computer-readable medium" includes any type of medium that can be accessed by a computer, such as a read-only memory (ROM), a random access memory (RAM), a hard drive, a compact disk (CD), a digital video disc (DVD) or any other type of memory. "Non-transitory" computer-readable media does not include wired, wireless, optical or other communication links that transmit temporary electrical signals or other signals. Non-transitory computer-readable media include media in which data can be permanently stored and media in which data can store data and overwrite it later, such as rewritable optical disks or erasable memory devices.

[0042] Definitions for certain other words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many, if not most, instances, such definitions apply to prior, as well as future uses of such defined words and phrases.

[0043] Discussed below Figures 1 to 18 The various embodiments used to describe the principles of the present disclosure in this patent document are for illustration only and should not be interpreted in any way as limiting the scope of the present disclosure. Those skilled in the art will appreciate that the principles of the present disclosure can be implemented in any appropriately arranged system or device.

[0044] In order to meet the increased demand for wireless data services since the deployment of 4G communication systems and to realize various vertical applications, 5G / NR communication systems have been developed and are currently being deployed. 5G / NR communication systems are considered to be implemented in high-frequency (millimeter wave) bands (e.g., 28 GHz or 60 GHz bands) to achieve high data rates, or in low-frequency bands (such as 6 GHz) to achieve robust coverage and mobility support. In order to reduce the propagation loss of radio waves and increase the transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technology are discussed in 5G / NR communication systems.

[0045] In addition, in the 5G / NR communication system, system network improvements are being developed based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, collaborative communications, coordinated multi-point (CoMP), receiving-end interference cancellation, etc.

[0046] The discussion of 5G systems and frequency bands associated therewith is for reference, as certain embodiments of the present disclosure may be implemented in 5G systems. However, the present disclosure is not limited to 5G systems or frequency bands associated therewith, and embodiments of the present disclosure may be used in conjunction with any frequency band. For example, aspects of the present disclosure may also be applied to 5G communication systems, 6G, or even later versions that may use terahertz (THz) frequency bands.

[0047] The following Figure 1-Figure 3 Various embodiments are described that are implemented in a wireless communication system and using Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) communication techniques. Figure 1-Figure 3 The description is not meant to imply physical or architectural limitations to the manner in which different embodiments may be implemented. Different embodiments of the present disclosure may be implemented in any suitably arranged communications system.

[0048] Figure 1 An example wireless network according to an embodiment of the present disclosure is shown. Figure 1 The embodiment of the wireless network shown in FIG. 1 is for illustration only. Other embodiments of the wireless network 100 may be used without departing from the scope of the present disclosure.

[0049] like Figure 1 As shown, the wireless network includes gNB 101 (e.g., base station BS), gNB 102, and gNB 103. gNB 101 communicates with gNB 102 and gNB 103. gNB 101 also communicates with at least one network 130 (such as the Internet, a proprietary Internet Protocol (IP) network, or other data network).

[0050] gNB 102 provides wireless broadband access to network 130 for a first plurality of user equipment (UE) within coverage area 120 of gNB 102. The first plurality of UEs includes UE 111, which may be located in a small business; UE 112, which may be located in an enterprise; UE 113, which may be a WiFi hotspot; UE 114, which may be located in a first residence; UE 115, which may be located in a second residence; and UE 116, which may be a mobile device such as a cellular phone, a wireless laptop, a wireless PDA, etc. gNB 103 provides wireless broadband access to network 130 for a second plurality of UEs within coverage area 125 of gNB 103. The second plurality of UEs includes UE 115 and UE 116. In some embodiments, one or more of gNBs 101-103 may communicate with each other and with UEs 111-116 using 5G / NR, Long Term Evolution (LTE), Long Term Evolution-Advanced (LTE-A), WiMAX, WiFi, or other wireless communication technologies.

[0051] Depending on the network type, the term "base station" or "BS" may refer to any component (or set of components) configured to provide wireless access to a network, such as a transmission point (TP), a transmission-reception point (TRP), an enhanced base station (eNodeB or eNB), a 5G / NR base station (gNB), a macro cell, a femto cell, a WiFi access point (AP), or other wirelessly enabled devices. The base station may provide wireless access according to one or more wireless communication protocols (e.g., 5G / NR Third Generation Partnership Project (3GPP) NR, Long Term Evolution (LTE), Advanced LTE (LTE-A), High Speed ​​Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc.). For convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to network infrastructure components that provide wireless access to remote terminals. In addition, depending on the network type, the term "user equipment" or "UE" may refer to any component, such as a "mobile station", "subscriber station", "remote terminal", "wireless terminal", "reception point", or "user equipment". For convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless device that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered a fixed device (such as a desktop computer or vending machine).

[0052] The dashed lines illustrate the approximate extents of coverage areas 120 and 125, which are shown as approximately circular for purposes of illustration and explanation only. It should be clearly understood that coverage areas associated with a gNB, such as coverage areas 120 and 125, may have other shapes, including irregular shapes, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles.

[0053] As described in more detail below, one or more of the UEs 111-116 include circuitry, programming, or a combination thereof for estimating channel state information in an advanced MIMO antenna system for cellular communications. In certain embodiments, one or more of the gNBs 101-103 include circuitry, programming, or a combination thereof for estimating channel state information in an advanced MIMO antenna system for cellular communications.

[0054] although Figure 1 An example of a wireless network is shown, but Figure 1Various changes may be made. For example, the wireless network may include any number of gNBs and any number of UEs in any suitable arrangement. In addition, gNB 101 may communicate directly with any number of UEs and provide wireless broadband access to network 130 to these UEs. Similarly, each gNB 102-103 may communicate directly with network 130 and provide direct wireless broadband access to network 130 to the UEs. In addition, gNBs 101, 102, and / or 103 may provide access to other or additional external networks, such as an external telephone network or other type of data network.

[0055] Figure 2 An example gNB 102 is shown according to an embodiment of the present disclosure. Figure 2 The embodiment of the gNB 102 shown in FIG. is for illustration only, and Figure 1 gNBs 101 and 103 may have the same or similar configurations. However, gNBs have a variety of configurations, and Figure 2 The scope of this disclosure is not limited to any particular implementation of gNB.

[0056] like Figure 2 As shown, the gNB 102 includes multiple antennas 205a-205n, multiple transceivers 210a-210n, a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0057] The transceivers 210a-210n receive incoming RF signals from the antennas 205a-205n, such as signals sent by UEs in the network 100. The transceivers 210a-210n downconvert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by the controller / processor 225 and / or receive (RX) processing circuits in the transceivers 210a-210n, which generate processed baseband signals by filtering, decoding and / or digitizing the baseband or IF signals. The controller / processor 225 may further process the baseband signals.

[0058] The controller / processor 225 and / or transmit (TX) processing circuitry in the transceivers 210a-210n receives analog or digital data (such as voice data, web data, email, or interactive video game data) from the controller / processor 225. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceivers 210a-210n up-convert the baseband or IF signal to an RF signal that is transmitted via the antennas 205a-205n.

[0059] The controller / processor 225 may include one or more processors or other processing devices that control the overall operation of the gNB 102. For example, the controller / processor 225 may control the reception of UL channel signals and the transmission of DL channel signals by the transceivers 210a-210n in accordance with well-known principles. The controller / processor 225 may also support additional functionality, such as more advanced wireless communication functionality. For example, the controller / processor 225 may support beamforming or directional routing operations, in which outgoing / incoming signals from / to multiple antennas 205a-205n are weighted differently to effectively direct the outgoing signals in a desired direction. The controller / processor 225 may support any of a variety of other functions in the gNB 102.

[0060] The controller / processor 225 is also capable of executing programs and other processes resident in the memory 230, such as processes for estimating channel state information in advanced MIMO antenna systems for cellular communications. The controller / processor 225 can move data into or out of the memory 230 as required by the executing process.

[0061] The controller / processor 225 is also coupled to a backhaul or network interface 235. The backhaul or network interface 235 allows the gNB 102 to communicate with other devices or systems via a backhaul connection or via a network. The interface 235 may support communication over any suitable wired or wireless connection. For example, when the gNB 102 is implemented as part of a cellular communication system (such as a cellular communication system supporting 5G / NR, LTE, or LTE-A), the interface 235 may allow the gNB 102 to communicate with other gNBs via a wired or wireless backhaul connection. When the gNB 102 is implemented as an access point, the interface 235 may allow the gNB 102 to communicate with a larger network (such as the Internet) via a wired or wireless local area network or via a wired or wireless connection. The interface 235 includes any suitable structure that supports communication over a wired or wireless connection, such as Ethernet or a transceiver.

[0062] Memory 230 is coupled to controller / processor 225. A portion of memory 230 may include RAM, and another portion of memory 230 may include flash memory or other ROM.

[0063] although Figure 2 An example of a gNB 102 is shown, but the Figure 2 For example, gNB 102 may include Figure 2 Any number of each component shown in Figure 2 The various components in may be combined, further subdivided, or omitted, and additional components may be added according to specific needs.

[0064] Figure 3 An example UE 116 is shown in accordance with an embodiment of the present disclosure. Figure 3 The embodiment of UE 116 shown in FIG. 1 is for illustration only, and Figure 1 UEs 111-115 may have the same or similar configurations. However, UEs have a variety of configurations, and Figure 3 The scope of the present disclosure is not limited to any particular implementation of a UE.

[0065] like Figure 3 As shown, UE 116 includes antenna 305, transceiver 310, and microphone 320. UE 116 also includes speaker 330, processor 340, input / output (I / O) interface (IF) 345, input 350, display 355, and memory 360. Memory 360 includes operating system (OS) 361 and one or more applications 362.

[0066] Transceiver 310 receives incoming RF signals from antenna 305 transmitted by a gNB of network 100. Transceiver 310 downconverts the incoming RF signals to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by processor 340 and / or RX processing circuitry in transceiver 310, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuitry transmits the processed baseband signal to speaker 330 (such as for voice data) or is processed by processor 340 (such as for web browsing data).

[0067] The processor 340 and / or the TX processing circuit in the transceiver 310 receives analog or digital voice data from the microphone 320 or other outgoing baseband data (such as web data, email, or interactive video game data) from the processor 340. The TX processing circuit encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The transceiver 310 up-converts the baseband or IF signal to an RF signal that is transmitted via the antenna 305.

[0068] The processor 340 may include one or more processors or other processing devices and execute the OS 361 stored in the memory 360 to control the overall operation of the UE 116. For example, the processor 340 may control the transceiver 310 to receive DL channel signals and transmit UL channel signals according to well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0069] Processor 340 is also capable of executing other processes and programs resident in memory 360, such as processes for estimating channel state information in advanced MIMO antenna systems for cellular communications.

[0070] Processor 340 can move data into or out of memory 360 as needed by the executing process. In some embodiments, processor 340 is configured to execute application 362 based on OS 361 or in response to signals received from a gNB or operator. Processor 340 is also coupled to I / O interface 345, which provides UE 116 with the ability to connect to other devices such as laptops and handheld computers. I / O interface 345 is the communication path between these accessories and processor 340.

[0071] The processor 340 is also coupled to an input 350 and a display 355m, which may include, for example, a touch screen, a keyboard, etc. An operator of the UE 116 may enter data into the UE 116 using the input 350. The display 355 may be a liquid crystal display, a light emitting diode display, or other display capable of presenting rendered text and / or at least limited graphics, such as from a website.

[0072] Memory 360 is coupled to processor 340. A portion of memory 360 may include random access memory (RAM), and another portion of memory 360 may include flash memory or other read-only memory (ROM).

[0073] although Figure 3 An example of UE 116 is shown, but the Figure 3 Make various changes. For example, Figure 3 The various components in may be combined, further subdivided, or omitted, and additional components may be added as required. As a specific example, processor 340 may be divided into multiple processors, such as one or more central processing units (CPUs) and one or more graphics processing units (GPUs). In another example, transceiver 310 may include any number of transceivers and signal processing chains, and may be connected to any number of antennas. In addition, although Figure 3 The UE 116 is shown configured as a mobile phone or smart phone, but the UE may be configured to operate as other types of mobile or stationary devices.

[0074] Figure 4 and Figure 5Example wireless transmit and receive paths according to the present disclosure are shown. In the following description, transmit path 400 may be described as being implemented in a gNB (such as gNB 102) and receive path 500 may be described as being implemented in a UE (such as UE 116). However, it is understood that receive path 500 may be implemented in a gNB and transmit path 400 may be implemented in a UE. In some embodiments, receive path 500 is configured to support estimating channel state information in an advanced MIMO antenna system for cellular communications.

[0075] like Figure 4 The transmit path 400 shown includes a channel coding and modulation block 405, a serial to parallel (S to P) block 410, an inverse fast Fourier transform (IFFT) block of size N 415, a parallel to serial (P to S) block 420, an add cyclic prefix block 425, and an upconverter (UC) 430. Figure 5 The receive path 500 shown includes a downconverter (DC) 555, a remove cyclic prefix block 560, a serial to parallel (S to P) block 565, a size N fast Fourier transform (FFT) block 570, a parallel to serial (P to S) block 575, and a channel decoding and demodulation block 580.

[0076] like Figure 4 As shown in , the channel coding and modulation block 405 receives a set of information bits, applies coding (such as low-density parity-check (LDPC) coding), and modulates the input bits (such as with quadrature phase-shift keying (QPSK) or quadrature amplitude modulation (QAM)) to generate a frequency-domain modulation symbol sequence.

[0077] Serial to parallel block 410 converts (such as demultiplexes) the serial modulation symbols into parallel data to generate N parallel symbol streams, where N is the IFFT / FFT size used in gNB 102 and UE 116. Size N IFFT block 415 performs an IFFT operation on the N parallel symbol streams to generate a time domain output signal. Parallel to serial block 420 converts (such as multiplexes) the parallel time domain output symbols from size N IFFT block 415 to generate a serial time domain signal. Add cyclic prefix block 425 inserts a cyclic prefix into the time domain signal. Up converter 430 modulates (such as upconverts) the output of add cyclic prefix block 425 to RF frequency for transmission via a wireless channel. The signal may also be filtered at baseband before conversion to RF frequency.

[0078] The RF signal transmitted from gNB 102 reaches UE 116 after passing through the wireless channel, and an operation opposite to that at gNB 102 is performed at UE 116.

[0079] like Figure 5As shown, the down converter 555 down-converts the received signal to the baseband frequency, and the remove cyclic prefix block 560 removes the cyclic prefix to generate a serial time domain baseband signal. The serial to parallel block 565 converts the time domain baseband signal into a parallel time domain signal. The size N FFT block 570 performs an FFT algorithm to generate N parallel frequency domain signals. The parallel to serial block 575 converts the parallel frequency domain signals into a sequence of modulated data symbols. The channel decoding and demodulation block 580 demodulates and decodes the modulation symbols to recover the original input data stream.

[0080] Each of gNBs 101-103 may implement Figure 4 The transmission path 400 shown is similar to the transmission to UE 111-116 in the downlink and can be implemented as follows Figure 5 Receive path 500 is shown, which is similar to receiving from UE 111-116 in the uplink. Similarly, each of UE 111-116 can implement transmit path 400 for transmitting to gNB 101-103 in the uplink, and can implement receive path 500 for receiving from gNB 101-103 in the downlink.

[0081] Figure 4 and Figure 5 Each of the components in may be implemented using hardware alone or a combination of hardware and software / firmware. As a specific example, Figure 4 and Figure 5 At least some components in can be implemented with software, while other components can be implemented by configurable hardware or a mixture of software and configurable hardware. For example, FFT block 570 and IFFT block 415 can be implemented as configurable software algorithms, wherein the value of size N can be modified according to the implementation.

[0082] In addition, although described as using FFT and IFFT, this is only for illustration and may not be construed as limiting the scope of the present disclosure. Other types of transforms may be used, such as discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT) functions. It will be appreciated that for DFT and IDFT functions, the value of variable N may be any integer (such as 1, 2, 3, 4, etc.), while for FFT and IFFT functions, the value of variable N may be any integer of a power of 2 (such as 1, 2, 4, 8, 16, etc.).

[0083] although Figure 4 and Figure 5 An example of a wireless transmit and receive path is shown, but the Figure 4 and Figure 5 Make various changes. For example, Figure 4 and Figure 5The various components in may be combined, further subdivided, or omitted, and additional components may be added according to specific needs. Figure 4 and Figure 5 It is intended to illustrate examples of the types of transmit and receive paths that may be used in a wireless network. Any other suitable architecture may be used to support wireless communications in a wireless network.

[0084] The unit for DL ​​signaling or UL signaling on a cell is called a time slot and may include one or more symbols. The bandwidth (BW) unit is called a resource block (RB). An RB includes multiple subcarriers (SC). For example, a time slot may have a duration of one millisecond, and an RB may have a bandwidth of 180 KHz and include 12 SCs with an inter-SC spacing of 15 KHz. A time slot may be a mixed time slot similar to a special subframe in a time division duplex (TDD) system, or a full UL time slot, or a full DL time slot.

[0085] DL signals include data signals conveying information content, control signals conveying DL control information (DCI), and reference signals (RS) also known as pilot signals. The gNB sends data information or DCI through the corresponding physical DL shared channel (PDSCH) or physical DL control channel (PDCCH). PDSCH or PDCCH can be sent on a variable number of time slot symbols including one time slot symbol. The spatial setting for PDCCH reception can be indicated to the UE based on the configuration of the value of the TCI state of the CORESET on which the UE receives the PDCCH. The spatial setting for PDSCH reception can be indicated to the UE based on the configuration of the higher layer or based on the indication of the value of the TCI state of the DCI format that schedules PDSCH reception. The gNB can configure the UE to receive signals on the cell within the DL bandwidth part (BWP) of the cell DL BW.

[0086] The gNB transmits one or more of multiple types of RS including channel state information RS (CSI-RS) and demodulation RS (DMRS). CSI-RS is primarily intended for UEs to perform measurements and provide channel state information (CSI) to the gNB. For channel measurements, non-zero power CSI-RS (NZP CSI-RS) resources are used. For interference measurement reports (IMRs), CSI interference measurement (CSI-IM) resources associated with zero power CSI-RS (ZP CSI-RS) configurations are used. The CSI process includes NZP CSI-RS and CSI-IM resources. The UE can determine the CSI-RS transmission parameters through DL control signaling or high-level signaling (such as RRC signaling from the gNB). The transmission instance of the CSI-RS can be indicated by DL control signaling or configured by high-level signaling. DMRS is transmitted only in the BW of the corresponding PDCCH or PDSCH, and the UE can use DMRS to demodulate data or control information.

[0087] The UL signal also includes a data signal conveying information content, a control signal conveying UL control information (UCI), a DMRS associated with data or UCI demodulation, a sounding RS (SRS) enabling the gNB to perform UL channel measurement, and a random access preamble enabling the UE to perform random access (RA). The UE transmits data information or UCI through a corresponding physical UL shared channel (PUSCH) or physical UL control channel (PUCCH). PUSCH or PUCCH is transmitted on a variable number of slot symbols including one slot symbol. The gNB can configure the UE to transmit a signal on a cell within the UL BWP of the cell UL BW.

[0088] UCI includes hybrid automatic repeat request acknowledgement (HARQ-ACK) information indicating correct or incorrect detection of a data transport block (TB) in the PDSCH, a scheduling request (SR) indicating whether the UE has data in the UE's buffer, and a CSI report that enables the gNB to select appropriate parameters for PDSCH or PDCCH transmission to the UE. The HARQ-ACK information can be configured with a smaller granularity than each TB and can be per data code block (CB) or per group of data CBs, where a data TB includes multiple data CBs.

[0089] The CSI report from the UE may include a channel quality indicator (CQI), which informs the gNB of the maximum modulation and coding scheme (MCS) for the UE to detect a data TB with a predetermined block error rate (BLER) (such as 10% BLER); a precoding matrix indicator (PMI), which informs the gNB how to combine signals from multiple transmitter antennas according to the MIMO transmission principle; and a rank indicator (RI), which indicates the transmission rank of the PDSCH. UL RS includes DMRS and SRS. DMRS is transmitted only in the BW of the corresponding PUSCH or PUCCH transmission. The gNB can use DMRS to demodulate the information in the corresponding PUSCH or PUCCH. SRS is sent by the UE to provide UL CSI to the gNB, and for TDD systems, SRS transmission can also provide PMI for DL ​​transmission. In addition, in order to establish synchronization or initial high-layer connection with the gNB, the UE can send a physical random access channel.

[0090] In the present disclosure, a beam is determined by either: (1) TCI state, which establishes a quasi-colocation (QCL) relationship between a source reference signal (e.g., synchronization signal / physical broadcast channel (PBCH) block (SSB) and / or CSI-RS) and a target reference signal; or (2) spatial relationship information, which establishes an association with a source reference signal (such as SSB or CSI-RS or SRS). In either case, the ID of the source reference signal identifies the beam.

[0091] The TCI state and / or the spatial relation reference RS may determine a spatial Rx filter for reception of a downlink channel at the UE, or a spatial Tx filter for transmission of an uplink channel from the UE.

[0092] Rel.14 LTE and Rel.15 NR support up to 32 CSI-RS antenna ports, which enables the eNB to be equipped with a large number of antenna elements (such as 64 or 128). In this case, multiple antenna elements are mapped to one CSI-RS port. For mmWave bands, although the number of antenna elements can be larger for a given form factor, the number of CSI-RS ports (which can correspond to the number of digital precoding ports) is often limited due to hardware constraints (such as the feasibility of installing a large number of ADCs / DACs at mmWave frequencies), such as Figure 6 shown.

[0093] Figure 6 An example antenna structure 600 is shown in accordance with an embodiment of the present disclosure. Figure 6 The embodiment of antenna structure 600 shown in FIG. 6 is for illustration only.

[0094] In this case, one CSI-RS port is mapped to a large number of antenna elements that can be controlled by a set of analog phase shifters 601. One CSI-RS port can then correspond to one subarray that produces a narrow analog beam through analog beamforming 605. The analog beam can be configured to scan across a wider range of angles 620 by changing the phase shifter set across symbols or subframes. The number of subarrays (equal to the number of RF chains) is proportional to the number of CSI-RS ports N. CSI-PORT The digital beamforming unit 610 spans N CSI-PORT The analog beams are linearly combined to further increase the precoding gain. While the analog beams are broadband (and therefore not frequency selective), the digital precoding can vary across frequency subbands or resource blocks. Receiver operation can be similarly envisioned.

[0095] Since the above-described system utilizes multiple simulated beams for transmission and reception (wherein one or a small number of simulated beams is selected from a large number of simulated beams, for example, from time to time after a training duration), the term "multi-beam operation" is used to refer to the entire system aspect. For the purpose of description, this includes indicating an assigned DL or UL TX beam (also referred to as "beam indication"), measuring at least one reference signal for calculating and performing beam reporting (also referred to as "beam measurement" and "beam reporting", respectively), and receiving DL or UL transmissions via selection of a corresponding RX beam.

[0096] The above system is also applicable to higher frequency bands, such as greater than 52.6 GHz. In this case, the system can use only analog beams. Due to the O2 absorption loss near the 60 GHz frequency (additional loss of about 10 dB at 100 m distance), a larger number and sharper analog beams (and therefore a larger number of radiators in the array) may be required to compensate for the additional path loss.

[0097] Figure 7 An example of an antenna panel 700 including NT antenna elements according to an embodiment of the present disclosure is shown. Figure 7 The embodiment of antenna panel 700 shown in FIG. 7 including NT antenna elements is for illustration only.

[0098] Figure 7 Describes the N T antenna elements divided into an equal number of elements (e.g. N A The total number of subarrays is denoted as N D , and N D =N T / N A .

[0099] Figure 8An example of an RF front-end and baseband implementation 800 of a base station according to an embodiment of the present disclosure is shown. Figure 8 The embodiment of the RF front end and baseband implementation 800 of the base station shown in FIG. 8 is for illustration only.

[0100] Figure 8 Shown is equipped with Figure 7 The RF front end and baseband implementation of the base station with antenna panels in FIG. The RF front end is a possible implementation of hybrid analog-digital beamforming. Figure 8 Construct the N to be transmitted from the antenna panel T An RF signal.

[0101] Starting from the right, L data streams or L modulation symbol sequences are provided to the digital beamformer (BF), which can convert the L streams into N D data streams, and multiply the resource elements of the PRB bundle k by its dimension N D ×L digital precoder Where k = 0, ..., N PRB-bundles -1, and N PRB-bundles is the total number of PRB bundles to which the data stream is mapped.

[0102] Then, N D The modulation symbols on each data stream are mapped to resource elements, modulated by OFDM, and finally converted to time domain samples. These time domain samples are converted to analog, modulated by the carrier, and for these N D Each of the paths obtains an analog signal.

[0103] Then, the analog signal passes through the analog BF block, where the size is N A ×1 analog precoder Applied to path d, where d=0, ..., N D -1. Apply simulated BF to all N D The signal on the path, N T =N A ×N D An RF signal is constructed on each antenna element.

[0104] Fig. 9 An example of a chain of signal processing modules 900 according to an embodiment of the present disclosure is shown. Fig. 9 The embodiment of the signal processing module chain 900 shown in FIG. 1 is for illustration only.

[0105] Fig. 9The chain of signal processing modules in a wireless transmit / receive system is shown. L2 (layer 2) is responsible for scheduling and L1 digital (layer) configuration. The L1 digital module generates frequency domain or time domain signals according to the configuration received from L2 and passes the time domain or frequency domain signals to the radio unit (RU). The RU then converts the digital signal to analog signal, modulates the signal to RF frequency, performs analog beamforming (if configured), and sends the signal over the air via the antenna.

[0106] For eXtreme MIMO (X-MIMO), which can be deployed in the upper mid-band (7 to 24 GHz carriers), the channel spectral efficiency is expected to increase many times and allow a very large number of antennas (e.g., 2048) and a large number of digital chains (e.g., 256). For X-MIMO, by utilizing these many antennas and channel degrees of freedom, 64-layer MU-MIMO and 16-layer SU-MIMO are feasible. However, multiple challenges arise due to dealing with so many antennas.

[0107] First, the complexity of constructing a 256×64 MU-MIMO channel matrix is ​​expected to be at least 64 times higher than the complexity of its 64×16 counterpart. Therefore, if the BS has 20 DSP cores to process 64×16, 256×64 requires 1280 DSP cores based on a direct extension of the 64×16 computation algorithm. Therefore, multiple techniques are needed to reduce the precoder complexity to a reasonable level.

[0108] Secondly, the channel state information (CSI) on the individual digital ports may be obtained at a lower SINR compared to the C-band (3.5GHz) counterparts. This is because the path loss is about 6-17dB higher at 7-24GHz in the upper mid-band, and the beamforming techniques used for the data channels for CSI acquisition may not be directly usable.

[0109] The baseband processing unit of the BS requires per-user CSI for single-user and multi-user MIMO beamforming and scheduling. Here, the CSI of user i includes at least the channel vector h i , channel vector h i Includes N for each resource element T entries. Length - N T Channel vector h i It can be represented by two components, length N D The digital channel vector and length N A N on the subarray D Channel vector The set of d=1,...,N D, according to the following formula:

[0110] In the general formula for this subarray with different simulated beams, the DU needs to estimate N T =N D ·N A entries, which can be as large as 2048 or even more, which requires large SRS resource overhead and computational complexity.

[0111] Therefore, low-complexity high-precision channel vector / matrix estimation for antenna panels with a very large number of antennas is crucial to achieve extreme MIMO performance gains.

[0112] The present disclosure provides a base station that employs a per-subarray hybrid analog-digital beamforming architecture to estimate channel state information using a sounding reference signal.

[0113] Fig.10 An example of SRS reception and processing 1000 according to an embodiment of the present disclosure is shown. Fig.10 The embodiment of SRS reception and processing 1000 shown in FIG. 1 is for illustration only.

[0114] Fig.11 An example of MIMO channel estimation 1100 according to an embodiment of the present disclosure is shown. Fig.11 The embodiment of MIMO channel estimation 1100 shown in FIG. 1 is for illustration only.

[0115] Fig. 9 A MIMO channel estimation method using SRS measurement input measured on multiple hybrid beams according to some embodiments of the present disclosure is described.

[0116] exist Fig.10 , starting from the left, the BS antennas are N on each subarray during a duration (eg, OFDM symbol duration or time slot duration). A The RF signal is received on an antenna.

[0117] At each sub-array, an analog receiver BF (Rx BF) is applied across those RF signals received at those elements comprising the sub-array. D The simulated beamforming weights (BFW) on the N subarrays are configured by the BS for a duration. The simulated RxBF block will receive N A The signals are combined into one RF signal.

[0118] Each RF signal passes through the rest of the processing chain until OFDM demodulation, resulting in a digital Rx signal stream in the frequency domain. Then, for each configured SRS resource, the Rx stream is demapped by RE so that a resource-specific SRS measurement stream can be obtained for each digital port. In this way, for each SRS resource, N D N on each digital port D SRS measurement streams (ie, one SRS measurement stream per digital port).

[0119] These SRS resources are allocated to the UE. The BS configures the UE with one or more SRS resources, where each SRS resource is used for the UE to transmit SRS on a UE antenna port on a specified set of resource elements, where a specific scrambling code is applied, for example, a ZC sequence with a specific cyclic shift configured by the BS is applied.

[0120] Then, N D These N D The Rx SRS measurement streams are passed through the digital Rx BF (or combiner) block, producing SRS measurement streams, where

[0121] The process durations and applying different simulated beams at different durations, which results in B SRS measurement streams, where It can be entered into Fig.11 The channel combiner described in .

[0122] In the context of hybrid analog-digital beamforming, the positive integer Also known as the number of digital beams, a positive integer Also known as the number of simulated beams, and is called the number of hybrid beams.

[0123] like Fig.11 As depicted in B SRS measurement streams are used to estimate the T Each antenna channel estimate is T =N D ·N A , which is the total number of antenna elements in the antenna panel.

[0124] To help reduce the complexity and overhead of SRS channel estimation, information on how to use these N B SRS measurement streams to estimate N T Some new methods for SRS on multiple antennas.

[0125] Among these methods, Fig.10 The hybrid beam-based MIMO channel estimator in effectively performs a linear combination of SRS measurements on these hybrid beams.

[0126] In some embodiments (method 1), it is provided that the same analog Rx BF is used across all sub-arrays in each duration, and an identity digital Rx BF (ie, a size of N) is applied. D ×N D The identity matrix (identitymatrix) is spanned Duration gets N D B SRS measurement streams. Note that the digital Rx BF block can be bypassed to obtain the same result as the identity matrix. In this case, N T The antenna channel vector h i It is calculated from B SRS measurements across B durations as follows: in, is the Kronecker product. The application of the same analog Rx beam is motivated by the fact that the physical channel responses of all subarrays on a given UE's subarray elements are similar in the far field.

[0127] Based on this method, the BS estimates the CSI h as follows i .

[0128] The BS receives all N signals across the panel for SRS during duration b. D The same simulated beam p is applied to each subarray. A (b). Then, in the application of size N D ×N D In the case of a digital precoder with the identity matrix, according to Figure 8 Get N D In this case, N SRS measurements are simulated for beam b in duration b. D SRS measurements correspond to b=1,......,B. Here, is the channel estimate of user i on digital port d, measured with analog beam b, and based on get. is the combined signal on digital port d at user i. By receiving the length N on the d-th subarray A The analog signal vector Apply the simulated beam p A (b) to obtain, that is,

[0129] After performing these steps B times, the BS obtains a set of B SRS measurement streams, each of which includes N D After obtaining these N D B SRS measurement streams (i.e., these simulated beams applied over B durations) on ), the BS estimates the CSI of user i according to the equation of method 1.

[0130] Fig.12 The method for obtaining each subcarrier N according to an embodiment of the present disclosure is shown. D 1200 for measuring a plurality of SRS channels. The BS method 1200 may be performed by a BS (eg, Figure 1 101-103) shown in . Fig.12 The embodiment of BS method 1200 shown in FIG. 1 is for illustration only. Fig.12 One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0131] Fig.12 FIG. 1 shows a method for obtaining N per subcarrier (or per tone) according to some embodiments of the present disclosure. D For an OFDM symbol configured for SRS, the BS measures all N D The subarrays are configured with the same analog beam selected from the B candidate beams. The base station can sequentially select analog beams across different SRS reception opportunities (i.e., OFDM symbols configured for SRS reception). For example, if there are N A = 4 simulated beams are to be applied to SRS reception, for example, beam 1, beam 2, beam 3 and beam 4, then these beams are sequentially applied across four different SRS reception opportunities. Then, according to some embodiments of the present disclosure, for each i and b, b=1,……,B。

[0132] like Fig.12 As shown, in step 1202, the BS configures the receiver to receive the SRS. In step 1204, the BS selects a simulated beam to apply to SRS reception. In step 1206, the BS retrieves the simulated beam weight vector. In step 1208, the BS configures the same weight vector. In step 1210, the BS uses the weight vector to combine N A In step 1212, the BS estimates the per-user channel. In step 1214, the BS converts each tone per user N DThe channel estimates are stored in memory.

[0133] Fig.13 FIG. 1 is a flowchart of a BS method 1300 for reconstructing a channel matrix according to an embodiment of the present disclosure. The BS method 1300 may be performed by a BS (eg, Figure 1 101-103) shown in . Fig.13 The embodiment of BS method 1300 shown in FIG. 1 is for illustration only. Fig.13 One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0134] Fig.13 A method according to some embodiments of the present disclosure is shown for reconstructing a channel matrix for multiple antenna ports including analog ports in addition to digital ports. The BS combines a set of channel estimates collected across multiple time durations to reconstruct a full channel matrix that includes dimensions associated with the analog ports as well as the digital ports. For each UE, according to some embodiments of the present disclosure, after collecting each subcarrier N D After performing B sets of SRS channel measurements, the BS selects a number of simulated beam indices that can be used for combining.

[0135] The BS combines a set of these channel estimates and reconstructs each subcarrier N A N D After combining, in addition to the digital port channel estimates, the analog port channel estimates are also available.

[0136] like Fig.13 As shown, in step 1302, the BS selects a plurality of simulated beam indices. In step 1304, the BS retrieves the same number of simulated beam weight vectors. In step 1306, the BS retrieves the same number of per-tone N D In step 1308, the BS generates N D N A In step 1310, the BS linearly combines the scaled weight vectors to reconstruct each tone N D N A A channel estimate.

[0137] Fig.14 FIG. 1 is a flow chart of a BS method 1400 for a subset of SRS simulation beams according to an embodiment of the present disclosure. The BS method 1400 may be performed by a BS (e.g., Figure 1 101-103) shown in . Fig.14The embodiment of BS method 1400 shown in FIG. 1 is for illustration only. Fig.14 One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0138] Fig.14 A method for UE-specifically selecting a subset of SRS analog beams for combining according to some embodiments of the present disclosure is shown. The flowchart is performed per user. For the down-selection of SRS beams that can be used for combining, the BS considers the SRS channel strength received on these different analog beams. In one example, the BS down-selects a subset of beams that achieve an SRS RSRP (or alternatively SINR or RSSI) greater than a threshold. These down-selected beams are used for combining instead of the full B sets to reconstruct the analog port channel estimates.

[0139] like Fig.14 As shown, in step 1402, the BS sets b and a threshold. In step 1404, the BS retrieves the RSRP of the bth set of SRS channel estimates. In step 1406, the BS determines whether the RSRP is greater than the threshold. In step 1408, the BS appends a beam index to B. In step 1410, the BS determines whether more beams are available. In step 1412, the BS sets B.

[0140] Fig.15a FIG. 1 is a flowchart of a BS method 1500 for configuring multiple SRS resources according to an embodiment of the present disclosure. The BS method 1500 may be performed by a BS (eg, Figure 1 101-103) shown in . Fig.15a The embodiment of BS method 1500 shown in FIG. 1 is for illustration only. Fig.15a One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0141] Fig.15aA method of configuring multiple SRS resources to a UE and later selectively turning off the UE's SRS transmission according to some embodiments of the present disclosure is shown. After generating SRS channel estimates based on all configured SRS resources, according to some embodiments, the BS runs an SRS beam subset selection process. The BS then sends information of the selected subset to the UE, which the UE can use to continue SRS transmission only on the selected subset of SRS resources. Alternatively, the BS sends information of the subset of SRS resources for which the UE needs to turn off SRS transmission. The BS sends the information via RRC, MAC CE, or DCI signaling.

[0142] like Fig.15a As shown, in step 1502, the BS configures an SRS resource set. In step 1504, the BS receives the SRS and obtains an SRS channel estimate on the resource. In step 1506, the BS down-selects a subset B of the SRS resources. In step 1508, the BS configures the UE to turn off sending SRS transmissions.

[0143] Fig.15b 1 is a flowchart of a UE method 1550 for configuring multiple SRS resources according to an embodiment of the present disclosure. The UE method 1550 may be performed by a UE (e.g., Figure 1 111-116) shown in . Fig.15b The embodiment of UE method 1550 shown in FIG. 1 is for illustration only. Fig.15b One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0144] like Fig.15b As shown, in step 1552, the UE receives a signal including N B In step 1554, the UE sends N SRS resources according to the BS signaling. B In step 1556, the UE receives a configuration to transmit SRS from these N SRS resources. B The UE selects a subset B of SRS resources from among the SRS resources. In step 1558, the UE stops transmission on those SRS resources that do not belong to subset B.

[0145] Fig.14 and Fig.15a and Fig.15bThese embodiments are useful for saving battery consumption of a UE by allowing the UE to not send SRS on those resources where the quality of the SRS channel estimate is limited because the SRS Rx beam direction is not aligned with the UE's channel direction.

[0146] Fig.16a 1 shows a flow chart of a BS method 1600 for notifying a down selection of an SRS resource according to an embodiment of the present disclosure. The BS method 1600 may be performed by a BS (eg, Figure 1 101-103) shown in . Fig.16a The embodiment of BS method 1600 shown in FIG. 1 is for illustration only. Fig.16a One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0147] Fig.16a A method for a BS to notify a UE of a downward selection of SRS resources according to some embodiments of the present disclosure is shown. The BS configures a plurality of SRS resources to the UE, and configures a first SRS and a second transmission for the plurality of SRS resources. The BS configures the UE to perform a first SRS transmission on a complete set of SRS resources as configured in an SRS resource set. The BS measures the signal quality of these SRS resources, and downwardly selects a subset B' of the SRS resources. Then, the BS configures the UE to perform a second SRS transmission on the subset B' of the SRS resources.

[0148] like Fig.16a As shown, in step 1602, the BS configures an SRS resource set. In step 1604, the BS configures the UE to perform SRS transmission on the resources. In step 1606, the BS selects a subset B of the SRS resources downward. In step 1608, the BS configures the UE to perform SRS transmission.

[0149] Fig.16b 1 shows a flow chart of a UE method 1650 for notifying a down selection of an SRS resource according to an embodiment of the present disclosure. The UE method 1650 may be performed by a BS (e.g., Figure 1 101-103) shown in . Fig.16b The embodiment of UE method 1650 shown in FIG. 1 is for illustration only. Fig.16b One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0150] like Fig.16b As shown, in step 1652, the UE receives a signal including N BIn step 1654, the UE generates an SRS resource set of N SRS resources, each of which is associated with an SRS-PathlossReferenceRS. B In step 1656, the UE receives a configuration to transmit SRS from these N SRS resources. B The UE selects a subset B of SRS resources from the SRS resources. In step 1658, the UE performs SRS transmission on the resources belonging to the subset B.

[0151] In some embodiments, DCI signaling is used to communicate with Fig.15a and Fig.15b Related SRS transmission triggering. The DCI field used for SRS triggering is a bitmap signaling, where each bit indicates whether a specific SRS resource needs to be turned on (ie, for the UE to transmit) or turned off (ie, for the UE to skip transmission).

[0152] In some embodiments, MAC CE signaling is used to configure these configured SRS resources in the on / off SRS resource set.

[0153] Thus, the UE receives an SRS resource set configuration and transmits SRS across all resources in the set. Some time later, the UE receives another indication via DCI or MAC CE to selectively turn off (or alternatively, selectively turn on) specific SRS resources among those resources in the configured SRS resource set. Thus, the UE stops transmitting SRS on those indicated "turned off" resources; and the UE continues to transmit SRS only on those indicated "turned on" resources.

[0154] exist Fig.15a and Fig.15b as well as Fig.16a and Fig.16b In the example, the UE is initially configured with N B =SRS resource set of 4 SRS resources. The UE is then configured to send SRS on those four SRS resources. After a period of time, the BS decides to turn off 2 of the 4 SRS resources and sends such DCI or MAC CE signaling. After receiving the signaling, the UE stops sending SRS on those "turned off" (or "disabled") SRS resources, while the UE continues to send SRS on those resources that are not turned off (or "not disabled" or "turned on").

[0155] Fig.17 FIG. 1 is a flow chart of a BS method 1700 for configuring and managing two SRS resource sets according to an embodiment of the present disclosure. The BS method 1700 may be performed by a BS (eg, Figure 1 101-103) shown in . Fig.17The embodiment of BS method 1700 shown in FIG. 1 is for illustration only. Fig.17 One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0156] Fig.17 Two SRS resource set configurations and managements according to some embodiments of the present disclosure are shown. The BS configures a first SRS resource set and a second SRS resource set for the UE. The BS configures periodic SRS transmission for the first SRS resource set and configures semi-persistent SRS transmission for the second SRS resource set. After receiving the SRS from the first set, according to some embodiments of the present disclosure, the BS downwardly selects SRS resources corresponding to the SRS Rx beam set B' that gives a relatively stronger Rx signal quality. The BS updates the semi-persistent SRS transmission configuration to turn on only those resources corresponding to these downwardly selected SRS Rx beams. When the BS receives other SRS transmissions on the first resource set, the BS re-evaluates the Rx signal quality on the Rx beam and updates the beam downward selection set B'. If the BS selects a new subset, the BS then updates the semi-persistent SRS configuration to turn on only those SRS resources corresponding to the newly selected SRS beams.

[0157] like Fig.17 As shown, in step 1702, the BS configures a first SRS resource set and a second SRS resource set. In step 1704, the BS configures periodic SRS transmission for the first set. In step 1706, the BS configures semi-persistent SRS transmission for the second set. In step 1708, after receiving the SRS from the first set, the BS selects resources downward and constructs a subset B of the resources. In step 1710, the BS configures the semi-persistent SRS to turn on only those resources corresponding to the subset B.

[0158] While Approach 1 simplifies channel estimation by making all simulated beams across all subarrays identical at each time instance, individual channel estimates (i.e., ) may suffer from large estimation errors, especially when the SRSSINR is low, which leads to poor h i estimation, low-quality MU-MIMO precoder, and low MU-MIMO throughput.

[0159] In order to improve the accuracy of SRS channel estimation and / or reduce the complexity of SRS channel estimation even under low SRS SINR conditions, another method (method 2) is provided. Using the new method, the channel vector of user i is constructed as follows:

[0160] Based on this method, the BS estimates the CSI h as follows i The BS applies the same simulated Rx BF across all subarrays in each duration, and uses The number of matrices Rx BF, to span Duration obtained SRS measurement stream.

[0161] BS in duration b 1 All N across panels during the period D The subarrays will have the same simulated beam p A (b 1 ) is applied to SRS reception. Then, by applying The digital Rx combiner matrix p D , N D SRS measurements are based on Figure 7 is obtained. In duration b 1 Inner N D The application size on the SRS measurement flow is Digital Rx Combiner D (b 1 ), BS obtains:

[0162] Thus, for each hybrid analog and digital beam Get an SRS Rx measurement stream Thus, Should The reconstructed equations based on method 2 are and The analog and digital beams of the network configuration are used to reconstruct h i .

[0163] In some embodiments, the selection vector set and Such that all vectors in the set are orthogonal to each other and have unit norm, i.e., the sum of the squared magnitudes of the entries add up to 1.

[0164] In one example, the vectors of the set of vectors are according to the column vectors of the DFT matrix.

[0165] In one example, the vectors of the set of vectors are those column vectors of a matrix constructed from the Kronecker product of the columns of the two DFT matrices.

[0166] For extreme MIMO base stations, where the number of antenna elements is in the order of thousands (in the order of 1000s) and these antennas are divided into subarrays in the order of hundreds (in the order of 100s), where analog beamforming is configured to be tunable per subarray at each time duration, the present disclosure helps the BS to reliably estimate CSI with low computational complexity.

[0167] Fig.18 1 shows a flow chart of a BS method 1800 for estimating channel state information according to an embodiment of the present disclosure. The BS method 1800 may be performed by a BS (e.g., Figure 1 101-103) shown in . Fig.18 The embodiment of BS method 1800 shown in FIG. 1 is for illustration only. Fig.18 One or more of the components shown in the may be implemented in dedicated circuits configured to perform the functions described, or one or more of the components may be implemented by one or more processors executing instructions to perform the functions described.

[0168] like Fig.18 As shown, the method 1800 starts at step 1802. In step 1802, the BS generates first configuration information including an SRS resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal.

[0169] In step 1804, the BS sends first configuration information to the UE.

[0170] In step 1806, the BS receives an SRS based on the first configuration information.

[0171] In step 1808, the BS selects a subset of the SRS resource set based on the SRS and the first configuration information. In one embodiment, the SRS resource set includes a first resource set and a second resource set, the first resource set is configured for SRS in periodic reception, and the second resource set is configured for SRS in semi-persistent reception.

[0172] In one embodiment, the first resource set is configured for all analog beams and down-select measurement operations to obtain a subset of the SRS resource set, and the second resource set is configured for at least one analog beam down-selected from all analog beams on the subset of the SRS resource set.

[0173] In step 1810, the BS generates second configuration information including a subset of the SRS resource set.

[0174] In one embodiment, the BS sends second configuration information to the UE; and receives the SRS from the UE based on a subset of the SRS resource set.

[0175] In one embodiment, the BS collects SRS channel estimates measured on analog beams via a multiple SRS measurement operation.

[0176] In one embodiment, the BS constructs a channel matrix based on the results of multiple SRS measurement operations collected from different analog beams.

[0177] In one embodiment, the BS identifies a simulated beam set to receive the SRS based on the DFT matrix, and receives the SRS based on the simulated beam set.

[0178] In one embodiment, the BS identifies the channel strength of the SRS received via different analog beams. In such an embodiment, the channel strength is identified based on a threshold and at least one of RSRP, RSSI, and SINR.

[0179] In one embodiment, the BS selects analog beams based on the channel strength of the SRS and combines the selected analog beams to perform an analog port channel estimation operation.

[0180] The above flow charts illustrate example methods that can be implemented according to the principles of the present disclosure, and various changes can be made to the methods shown in the flow charts herein. For example, although shown as a series of steps, the individual steps in each figure can overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, a step can be omitted or replaced by another step.

[0181] Although the present disclosure has been described using exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. The present disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims. Any description in this application should not be construed as implying that any particular element, step or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined by the claims.

Claims

1. A base station (BS) in a communication system, the BS comprising: a processor configured to generate first configuration information including a sounding reference signal (SRS) resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal; and A transceiver operatively coupled to the processor, the transceiver being configured to: sending first configuration information to a user equipment (UE), and receiving an SRS based on the first configuration information, The processor is further configured to: selecting a subset of the SRS resource set based on the SRS and the first configuration information, and Second configuration information including a subset of the SRS resource set is generated.

2. The BS according to claim 1, wherein: The transceiver is also configured to: Sending second configuration information to the UE; and An SRS is received from the UE based on a subset of the SRS resource set.

3. The BS according to claim 1, wherein: The processor is also configured to collect SRS channel estimates measured on the simulated beams via the multiple SRS measurement operation.

4. The BS according to claim 3, wherein: The processor is further configured to construct a channel matrix based on results of the multiple SRS measurement operations collected from the different analog beams.

5. The BS according to claim 1, wherein: The processor is further configured to identify a set of analog beams to receive the SRS based on a discrete Fourier transform (DFT) matrix; as well as The transceiver is also configured to receive the SRS based on the set of analog beams.

6. The BS according to claim 1, wherein: The processor is further configured to: identify channel strengths of SRSs received via different analog beams; Selecting a simulated beam based on the channel strength of the SRS; and combining the selected analog beams to perform an analog port channel estimation operation, The channel strength is identified based on a threshold and at least one of a reference signal received power (RSRP), a received signal strength indicator (RSSI), and a signal to interference and noise ratio (SINR).

7. The BS according to claim 1, wherein: The SRS resource set includes a first resource set and a second resource set; The first resource set is configured for a periodically received SRS; The second resource set is configured for SRS for semi-persistent reception; The first resource set is configured for all simulated beams and down-select measurement operations to obtain a subset of the SRS resource set; as well as The second set of resources is configured for at least one simulated beam selected downward from all simulated beams on a subset of the set of SRS resources.

8. A method performed by a base station (BS) in a communication system, the method comprising: generating first configuration information including a sounding reference signal (SRS) resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal; Sending first configuration information to a user equipment (UE); Receiving the SRS based on the first configuration information; Selecting a subset of the SRS resource set based on the SRS and the first configuration information; as well as Second configuration information including a subset of the SRS resource set is generated.

9. The method according to claim 8, further comprising: Sending second configuration information to the UE; as well as An SRS is received from the UE based on a subset of the SRS resource set.

10. The method according to claim 8, further comprising: collecting SRS channel estimates measured on the simulated beams via a multiple SRS measurement operation; as well as A channel matrix is ​​constructed based on the results of multiple SRS measurement operations collected from different simulated beams.

11. The method according to claim 8, further comprising: identifying a set of simulated beams to receive the SRS based on a discrete Fourier transform (DFT) matrix; as well as The SRS is received based on the analog beam set.

12. The method according to claim 8, further comprising: Identifying channel strengths of SRS received via different analog beams; Selecting analog beams based on the channel strength of the SRS; as well as combining the selected analog beams to perform an analog port channel estimation operation, The channel strength is identified based on a threshold and at least one of a reference signal received power (RSRP), a received signal strength indicator (RSSI), and a signal to interference and noise ratio (SINR).

13. The method according to claim 8, wherein: The SRS resource set includes a first resource set and a second resource set; The first resource set is configured for a periodically received SRS; The second resource set is configured for SRS for semi-persistent reception; The first resource set is configured for all simulated beams and down-select measurement operations to obtain a subset of the SRS resource set; as well as The second set of resources is configured for at least one simulated beam selected downward from all simulated beams on a subset of the set of SRS resources.

14. A user equipment (UE), comprising: a transceiver configured to receive first configuration information from a base station (BS); as well as a processor operatively coupled to the transceiver, the processor configured to identify first configuration information including a set of sounding reference signal (SRS) resources, each SRS resource in the set of SRS resources being associated with an SRS-path loss reference signal for transmitting the SRS, in: The transceiver is further configured to send an SRS to the BS based on the first configuration information, A subset of the SRS resource set is selected based on the SRS and the first configuration information, and The second configuration information including the subset of the SRS resource set is based on the subset identification of the SRS resource set.

15. A method performed by a user equipment (UE), the method comprising: receiving first configuration information from a base station (BS); identifying first configuration information including a sounding reference signal (SRS) resource set, each SRS resource in the SRS resource set being associated with an SRS-path loss reference signal for transmitting the SRS; as well as Sending an SRS to the BS based on the first configuration information, in: A subset of the SRS resource set is selected based on the SRS and the first configuration information, and The second configuration information including the subset of the SRS resource set is based on the subset identification of the SRS resource set.

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