Method and apparatus for layered beamforming and reciprocity calibration for hybrid MIMO systems in wireless communication systems

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A hybrid MIMO system includes N digital transceiver chains and N analog beamformers, each analog beamformer coupled to one of the digital transceiver chains and including M analog TX chains and M analog RX chains. One of the simulated RX chains is an RX reference node, and one of the simulated TX chains is a TX reference node. For each beamformer, the processor measures TX and RX phase responses and TX and RX amplitude responses of TX and RX reference nodes, respectively, using a transceiver chain and a calibration transceiver; determining a reciprocity calibration based on a phase difference between the TX and RX phase responses and an amplitude difference between the TX and RX amplitude responses; and applying a reciprocity calibration to the stored beam definition to correct the phase and amplitude difference.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to a beamforming antenna array in a wireless communication system. Embodiments of the present disclosure relate to a method and apparatus for hierarchical beamforming calibration and reciprocity calibration for a hybrid multiple-input multiple-output antenna array system. BACKGROUND

[0002] Considering the evolution of generations of wireless communication, technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. After the commercialization of 5G (5th generation) communication systems, it is expected that the number of connected devices will grow exponentially. These devices will increasingly be connected to communication networks. Examples of networked things can include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machinery, and factory equipment. Mobile devices are expected to evolve in various form factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond 5G systems.

[0003] It is expected that 6G communication systems to be commercialized around 2030 will have a peak data rate of tera (1,000 giga) bps per second and a radio latency of less than 100 μsec, and thus will be 50 times faster than 5G communication systems and have 1 / 10 of the radio latency thereof.

[0004] In order to achieve such high data rates and ultra-low latency, it has been considered to implement 6G communication systems in a terahertz (THz) band (e.g., 95 giga hertz (GHz) to 3 THz bands). It is expected that, since path loss and atmospheric absorption in the THz band are more severe than in the mmWave band introduced in 5G, technologies to secure signal transmission distance (that is, coverage) will become more crucial. As major technologies to secure coverage, it is necessary to develop radio frequency (RF) elements, antennas, new waveforms having better coverage than orthogonal frequency division multiplexing (OFDM), beamforming, and massive multiple input multiple output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, and multi-antenna transmission techniques such as large scale antennas. In addition, there are ongoing discussions on new technologies to improve coverage of THz band signals, such as lenses and antennas based on metamaterials, orbital angular momentum (OAM), and reconfigurable intelligent surfaces (RIS).

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

[0006] Research and development of hyperconnected 6G communication systems, including human-to-machine (P2M) and machine-to-machine (M2M), are expected to enable the following hyperconnected experiences. In particular, it is expected that services such as truly immersive extended reality (XR), high-fidelity mobile holograms, and digital replicas can be provided through 6G communication systems. In addition, services such as secure and reliable remote surgery, industrial automation, and emergency response will be provided through 6G communication systems, so that these technologies can be applied in various fields such as industry, medical care, automobiles, and home appliances. SUMMARY

[0007] TECHNICAL PROBLEM

[0008] Currently, there is a need for enhanced hierarchical beamforming calibration and reciprocity calibration of hybrid MIMO antenna arrays in wireless communication systems.

[0009] SOLUTION TO THE PROBLEM

[0010] Embodiments of the present disclosure provide methods and apparatuses that facilitate hierarchical beamforming calibration and reciprocity calibration of hybrid MIMO antenna array systems.

[0011] In one embodiment, a hybrid MIMO system is provided, the system comprising: a first number (N) of digital transceiver chains; Nanalog beamformers, each analog beamformer operably coupled to a respective one of the digital transceiver chains; a calibration transceiver; and a processor operably coupled to the calibration transceiver, the digital transceiver chains, and the analog beamformers. Each analog beamformer includes a second number (M) of analog transmitter (TX) chains and M analog receiver (RX) chains, wherein one of the analog RX chains is an RX reference node and one of the analog TX chains is a TX reference node; and a memory operably coupled to the analog TX chains and the analog RX chains and configured to store beam definitions. The calibration transceiver is operably coupled to the TX reference node and the RX reference node of each analog beamformer. For each analog beamformer, the processor is configured to: measure, using the corresponding digital transceiver chain and the calibration transceiver, a TX phase response and a TX magnitude response of the TX reference node and a RX phase response and a RX magnitude response of the RX reference node; determine reciprocity calibration based on a phase difference between the TX phase response and the RX phase response and a magnitude difference between the TX magnitude response and the RX magnitude response; and apply the reciprocity calibration to the beam definitions to correct for the phase difference and the magnitude difference.

[0012] In another embodiment, a method of operating a hybrid MIMO system is provided, the system including a first number (N) of digital transceiver chains, N analog beamformers, and a calibration transceiver. The method includes the following steps: for each analog beamformer, measuring, using the corresponding digital transceiver chain and the calibration transceiver, a transmitter (TX) phase response and a TX magnitude response of a TX reference node of the analog beamformer and a receiver (RX) phase response and a RX magnitude response of a RX reference node of the analog beamformer, wherein each analog beamformer includes a second number (M) of analog TX chains and M analog RX chains, one of the analog RX chains being the RX reference node and one of the analog TX chains being the TX reference node. The method further includes: determining, for each analog beamformer, reciprocity calibration based on a phase difference between the TX phase response and the RX phase response and a magnitude difference between the TX magnitude response and the RX magnitude response; and applying the reciprocity calibration to stored beam definitions of each analog beamformer to correct for the phase difference and the magnitude difference.

[0013] In another embodiment, a non-transitory computer readable medium is provided. The non-transitory computer readable medium is configured to store instructions that, when executed by a processor, cause a system including a first number (N) of digital transceiver chains, NA hybrid MIMO system of analog beamformers and calibration transceivers: for each analog beamformer, using a corresponding digital transceiver chain and a calibration transceiver to measure a transmitter (TX) phase response and a TX amplitude response of a TX reference node of the analog beamformer and a receiver (RX) phase response and a RX amplitude response of a RX reference node of the analog beamformer, wherein each analog beamformer includes a second number (M) of analog TX chains and M one of the analog RX chains is the RX reference node and one of the analog TX chains is the TX reference node. The instructions also cause the hybrid MIMO system to determine, based on a phase difference between the TX phase response and the RX phase response and an amplitude difference between the TX amplitude response and the RX amplitude response, an reciprocity calibration for each analog beamformer; and apply the reciprocity calibration to stored beam definitions for each analog beamformer to correct for the phase difference and the amplitude difference.

[0014] Other technical features can be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0015] Before undertaking a detailed description of the following detailed description, it can be advantageous to set forth definitions of certain terms used throughout this patent document. The term "coupled" and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms "transmit," "receive," and "communicate," as well as derivatives thereof, encompass both direct and indirect communication. The terms "include" and "comprise," as well as derivatives thereof, mean inclusion without limitation. The term "or" is inclusive, meaning and / or. The phrase "associated with," as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, be adjacent to, be interposed with, be bound to or with, have a property of, have relations with, have agreements with, or other similar spatial and / or functional relations. 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 functionality associated with any particular controller can be centralized or distributed, whether locally or remotely. The phrase "at least one of means one or more of the items can be used in any combination. For example, "at least one of A, B, and C" includes A alone, B alone, C alone, as well as any combination of A, B, and C. As used herein, terms such as "first" and "second," or "third" and "fourth," etc. can be employed merely for distinguishing between similar entities, and do not in themselves indicate an ordering or a sequence. It is to be understood that if there is mention of an element (e.g., a first element) communicating with or connected with another element (e.g., a second element), it means that the first element can be directly or indirectly connected with the second element by way of a third element. For example , the first element) being "coupled with," "coupled to," "connected with," or "connected to" another element (the second element) means that the element can be directly or indirectly connected with the other element by way of a third element. For example , the first element) being "coupled with," "coupled to," "connected with," or "connected to" another element (the second element) means that the element can be directly or indirectly connected with the other element by way of a third element. For example , the first element) being "coupled with," "coupled to," "connected with," or "connected to" another element (the second element) means that the element can be directly or indirectly connected with the other element by way of a third element.

[0016] As used herein, the term "module" can include a unit implemented in hardware, software, or firmware, and can interchangeably be used with other terms, for example, "logic," "logic block," "component," or "circuitry". A module can be a single integral component, or a minimum unit or part thereof, adapted to perform one or more functions. For example, a module can be implemented in a form of an application-specific integrated circuit (ASIC).

[0017] Moreover, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof applicable for implementation. The phrase "computer readable medium" includes any medium that can be accessed by a computer. The

[0018] Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art will understand that in many, if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases.

[0019] Discussion of 5G systems and frequency bands associated therewith is provided for reference as certain embodiments of the present disclosure can 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 can be used in conjunction with any frequency band. For example, aspects of the present disclosure can also apply to 5G communication systems that can use terahertz (THz) frequency bands, 6G or even higher versions of deployment. BRIEF DESCRIPTION OF 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 in which like parts are marked with like numerals throughout the drawings, and in which: Figure 1 An exemplary wireless network is shown in accordance with various embodiments of the present disclosure; Figure 2 An exemplary gNB is shown in accordance with embodiments of the present disclosure; Figure 3 An exemplary UE is shown in accordance with embodiments of the present disclosure; Figure 4 An exemplary massive MIMO system is shown in accordance with embodiments of the present disclosure; Figure 5A An example of a partially connected hybrid MIMO TX system is shown in accordance with embodiments of the present disclosure; Figure 5B An example of a partially connected hybrid MIMO RX system is shown in accordance with embodiments of the present disclosure; Figure 6A An example of an OTA beamforming calibration procedure for TX beamforming is shown in accordance with embodiments of the present disclosure; Figure 6B An example of an OTA beamforming calibration procedure for RX beamforming is shown in accordance with embodiments of the present disclosure; Figure 7A An example of global reciprocity calibration for a TX system is shown in accordance with embodiments of the present disclosure; Figure 7B An example of global reciprocity calibration for a RX system is shown in accordance with embodiments of the present disclosure; Figure 8 An example procedure for hierarchical reciprocity calibration for a hybrid MIMO system is shown in accordance with embodiments of the present disclosure; Figure 9 An example block diagram of a hybrid MIMO system with hierarchical reciprocity calibration is shown in accordance with embodiments of the present disclosure; Figure 10 An example hybrid MIMO system is shown in accordance with embodiments of the present disclosure; Figure 11A An example of global TX reciprocity calibration for a hybrid MIMO system is shown in accordance with embodiments of the present disclosure; Figure 11B An example of global RX reciprocity calibration for a hybrid MIMO system is shown in accordance with embodiments of the present disclosure; Figure 12 An example procedure for performing hierarchical global reciprocity calibration in a hybrid MIMO system is shown in accordance with various embodiments of the present disclosure; Figure 13 A block diagram of the structure of a terminal (or user equipment) in accordance with various embodiments of the present disclosure is shown; and Figure 14 A block diagram of the structure of a base station in accordance with various embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0021] To meet the demand for wireless data traffic having increased since deployment of 4G communication systems and to enable various vertical applications, 5G / NR communication systems have been developed and are currently being deployed. The 5G / NR communication system is considered to be implemented in higher frequency (millimeter wave) bands, e.g., 28 GHz or 60 GHz bands, as compared with the 4G communication system to enable higher data rates or in lower frequency bands such as 6 GHz to enable robust coverage and mobility support. To decrease the propagation loss of radio waves and increase the transmission distance, beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beam forming, and large scale antennas techniques are discussed in 5G / NR communication systems.

[0022] In addition, in 5G / NR communication systems, development for system network improvement is under way based on advanced small cells, cloud radio access networks (RANs), ultra-dense networks, a device-to-device (D2D) communication, wireless backhaul, moving networks, cooperative communication, coordinated multi-points (CoMP), reception-end interference cancellation, and the like.

[0023] Massive MIMO is a key technology in 5G in which multiple antennas are used to serve multiple users simultaneously. In radio access technologies beyond 5G, the trend toward larger array sizes with more elements continues. However, to reduce the additional complexity of more antennas, hybrid MIMO systems are being considered. In hybrid MIMO, digital beamforming is combined with analog beamforming to reduce the number of digital transceivers (TRXs) needed.

[0024] The Figures 1 to 14 The various embodiments discussed in this patent document are presented for the purpose of illustration and description only and not by way of limitation of the scope of the disclosure. Those skilled in the art will understand that the principles of the disclosure can be implemented in any suitably arranged system or device.

[0025] Embodiments of the disclosure recognize that massive MIMO time division duplex (TDD) base stations rely on channel reciprocity to efficiently acquire downlink (DL) channel state information (CSI) through sounding signals in the uplink (UL) for multi-user MIMO precoding operations. Gain and phase offsets between the base station transmitter and receiver chains can break the reciprocity. To maintain the reciprocity of the downlink and uplink, reciprocity calibration is typically done periodically through a calibration network during normal operation of the base station.

[0026] When analog beamforming circuitry is added on top of a digital beamforming system in a base station, the combination of digital and analog beamforming is referred to as a hybrid massive MIMO base station system. The analog beamformer provides additional beamforming gain in both transmit and receive paths to achieve higher link budget. However, due to the use of multiple RF components such as power amplifiers (PAs), low noise amplifiers (LNAs), phase shifters, and filters in the analog beamformer, the complexity of reciprocity calibration increases dramatically.

[0027] Accordingly, embodiments of the present disclosure provide a method for performing reciprocity calibration in a hybrid MIMO system by layer-wise calibration of an analog beamformer and then correcting reciprocity errors, and an architecture that reduces the reciprocity calibration circuitry requirement to be commensurate with the number of digital ports, not the number of analog antenna ports.

[0028] The following description is directed to certain embodiments of the disclosure for the purposes of describing the innovative aspects of this disclosure. However, it is not intended to limit the scope of the disclosure to these embodiments alone. Figures 1 to 3 Various embodiments are described in the context of wireless communication systems and implemented with Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA) communication techniques. Figures 1 to 3 The description of the different embodiments of the disclosure is not intended to suggest that physical or architectural limitations of the ways in which different embodiments can be implemented. Different embodiments of the disclosure can be implemented in any suitably-arranged communication system.

[0029] Figure 1 An example wireless network according to embodiments of the disclosure is illustrated. Figure 1 The illustrated embodiment of the wireless network is merely for illustration. Other embodiments of the wireless network 100 can be used without departing from the scope of the disclosure.

[0030] As Figure 1 As illustrated, the wireless network includes a gNB 101 (e.g., base station, BS), a gNB 102, and a gNB 103. The gNB 101 communicates with the gNB 102 and the gNB 103. The gNB 101 also communicates with at least one network 130, such as the Internet, a proprietary Internet Protocol (IP) network, or other data network.

[0031] The gNBs 102 provides wireless broadband access to the network 130 for a first plurality of user equipment units (UEs) within a coverage area 120 of the gNB 102. The first plurality of UEs includes a UE 111, which can be located in a small business; a UE 112, which can be located in a enterprise; a UE 113, which can be a WiFi hotspot; a UE 114, which can be located in a first residence; a UE 115, which can be located in a second residence; and a UE 116, which can be a mobile device, such as a cell phone, a wireless laptop, a wireless PDA, or the like. The gNB 103 provides wireless broadband access to the network 130 for a second plurality of UEs within a coverage area 125 of the gNB 103. The second plurality of UEs includes the UEs 115 and 116. In some embodiments, one or more of the gNBs 101-103 can communicate with each other and with the UEs 111-116 using 5G / NR, Long Term Evolution (LTE), Long Term Evolution-Advanced (LTE-A), WiMAX, WiFi, or other wireless communication techniques.

[0032] Depending on the network type, the term "base station" or "BS" can refer to any component (or collection of components) configured to provide wireless access to a network, such as a transmit point (TP), transmit-receive point (TRP), an enhanced NodeB (eNodeB or eNB), a 5G / NR base station (gNB), a macrocell, a femtocell, a WiFi access point (AP), or other wirelessly enabled devices. A base station can provide wireless access to a plurality of UEs according to one or more wireless communication protocols, such as 5G / NR Third Generation Partnership Project (3GPP) NR, Long Term Evolution (LTE), LTE Advanced (LTE-A), High Speed Packet Access (HSPA), Wi-Fi 802.11a / b / g / n / ac, etc. For the sake of convenience, the terms "BS" and "TRP" are used interchangeably in this patent document to refer to a network infrastructure component that provides wireless access to remote terminals. Depending on the network type, the term "user equipment" or "UE" can refer to any component such as "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receive point," or "user device." For the sake of convenience, the terms "user equipment" and "UE" are used in this patent document to refer to a remote wireless equipment that wirelessly accesses a BS, whether the UE is a mobile device (such as a mobile telephone or smartphone) or is normally considered a fixed device (such as a desktop computer or vending machine).

[0033] Dotted lines show the approximate extents of the coverage areas 120 and 125, which are shown as approximately circular for the purposes of illustration and explanation only. It should be clearly understood that the coverage areas associated with gNBs, such as the coverage areas 120 and 125, can have other shapes, including irregular shapes, depending upon configuration of the gNBs and variations in the radio environment associated with natural and man-made obstructions.

[0034] Although Figure 1 various changes can be made to Figure 1 the wireless network. For example, the wireless network can include any number of gNBs and any number of UEs, arranged any suitable way. Additionally, gNB 101 can communicate directly with any number of UEs and provide those UEs access to network 130 via wireless broadband. Similarly, each of gNBs 102-103 can communicate directly with network 130 and provide UEs access to network 130 directly. Further, gNBs 101, 102, and / or 103 can provide access to other or additional external networks, such as external telephone networks or other types of data networks.

[0035] Figure 2 An example gNB 102 according to embodiments of the present disclosure is illustrated. Figure 2 The illustrated embodiment of gNB 102 is merely an example and Figure 1 gNBs 101 and 103 can have the same or similar configuration. However, gNBs have a wide variety of configurations and Figure 2 without limiting the scope of the present disclosure to any particular implementation of a gNB.

[0036] As Figure 2 illustrated, gNB 102 includes multiple antennas 205a-205n, multiple transceivers 210a-210n, a controller / processor 225, memory 230, and a backhaul or network interface 235.

[0037] The RF transceivers 210a-210n receive, from the antennas 205a-205n, incoming RF signals such as signals transmitted by UEs in the network 100. The transceivers 210a-210n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are processed by the transceivers 210a-210n and / or RX processing circuitry in the controller / processor 225 by filtering, decoding, and / or digitizing the baseband or IF signals, to generate processed baseband signals. The controller / processor 225 can further process the baseband signals.

[0038] Transceiver 210a-210n and / or transmit (TX) processing circuitry in controller / processor 225 receives analog or digital data, such as voice data, web data, e-mail, or interactive video game data, from controller / processor 225. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate processed baseband or IF signals. Transceiver 210a-210n up-converts the baseband or IF signals to RF signals by frequency mixing with an appropriate carrier frequency and amplifies the converted signals to generate transmit signals. The transmit signals are then routed through appropriate matching circuits and filters to antenna 205a-205n for transmission.

[0039] Controller / processor 225 can include one or more processors or other processing devices to manage the overall operation of gNB 102. For example, controller / processor 225 can control the reception of

[0040] Controller / processor 225 can also execute programs and other processes resident in memory 230, such as an OS. Controller / processor 225 can move data into or out of memory 230 as needed by processes executing on controller / processor 225.

[0041] Controller / processor 225 is also coupled to backhaul or network interface 235. Backhaul or network interface 235 allows gNB 102 to communicate with other devices or systems, e.g., through a backhaul connection or through a network. Interface 235 can support communication over any suitable wired or wireless connection. For example, when gNB 102 is implemented as part of a cellular communication system (such as a 5G / NR, LTE, or LTE-A cellular communication system), interface 235 can allow gNB 102 to communicate with other gNBs over a wired or wireless backhaul connection. When gNB 102 is implemented as an access point, interface 235 can allow gNB 102 to communicate with other gNBs over a wired or wireless local area network or through a wired or wireless connection to a larger network, such as the Internet. Interface 235 includes any suitable structure supporting communication over a wired or wireless connection, such as an Ethernet or Bluetooth interface.

[0042] Memory 230 is coupled to controller / processor 225. Part of memory 230 can include RAM, and another part of memory 230 can include flash memory or other ROM.

[0043] Although Figure 2 An example of gNB 102 is shown, but it is possible to compare it with other models. Figure 2 Various changes can be made. For example, gNB 102 can include any number of Figure 2 Each component is shown. Additionally... Figure 2 The various components can be combined, further subdivided, or omitted, and additional components can be added as needed.

[0044] Figure 3 An exemplary UE 116 according to an embodiment of the present disclosure is shown. Figure 3 The embodiment of UE 116 shown is for illustrative purposes only, and Figure 1 UEs 111 to 115 can have the same or similar configurations. However, UEs have a wide variety of configurations, and Figure 3 This disclosure is not intended to limit the scope of any particular implementation of the UE.

[0045] like Figure 3 As shown, UE 116 includes an antenna 305, a transceiver 310, and a microphone 320. UE 116 also includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, an input terminal 350, a display 355, and memory 360. Memory 360 includes an operating system (OS) 361 and one or more application programs 362.

[0046] Transceiver 310 receives incoming RF signals transmitted by a gNB of network 100 from antenna 305. Transceiver 310 down-converts the incoming RF signals to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is processed by an RX processing circuitry system in transceiver 310 and / or processor 340, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. The RX processing circuitry system sends the processed baseband signal to speaker 330 (e.g., for voice data) or to processor 340 (e.g., for web browsing data).

[0047] The TX processing circuitry in transceiver 310 and / or processor 340 receives analog or digital voice data from microphone 320 or other outgoing baseband data (such as web data, email, or interactive video game data) from processor 340. The TX processing circuitry encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. Transceiver 310 up-converts the baseband or IF signal into an RF signal transmitted via antenna 305.

[0048] The processor 340 can include one or more processors or other processing devices and execute the OS 361 stored in the memory 360 in order to control the overall operation of the UE 116. For example, the processor 340 can control the reception of DL channel signals and the transmission of UL channel signals by the transceiver 310 in accordance with well-known principles. In some embodiments, the processor 340 includes at least one microprocessor or microcontroller.

[0049] The processor 340 is also capable of executing other processes and programs stored in the memory 360. The processor 340 can move data into or out of the memory 360 as required by the processes executing. In some embodiments, the processor 340 is configured to execute the applications 362 based on the OS 361 or in response to signals received from gNBs or an operator. The processor 340 is also coupled to the I / O interface 345, which provides the UE 116 with the ability to connect to other devices such as laptop computers and handheld computers. The I / O interface 345 is the communication path between these accessories and the processor 340.

[0050] The processor 340 is also coupled to the input 350 (which includes, e.g., a touchscreen, keypad, etc.) and the display 355. The operator of the UE 116 can use the input 350 to enter data into the UE 116. The display 355 can be a liquid crystal display, light emitting diode display, or other display capable of rendering text and / or at least limited graphics, such as from web sites.

[0051] The memory 360 is coupled to the processor 340. Part of the memory 360 can include a random access memory (RAM), and another part of the memory 360 can include a flash memory or other read-only memory (ROM).

[0052] Although Figure 3 One example of a UE 116 is shown, but various changes can be made Figure 3 For example, Figure 3 Various components in the UE 116 can be combined, further subdivided, or omitted and additional components can be added according to particular needs but, as a specific example, the processor 340 can 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, the transceiver 310 can include any number of transceivers and signal processing chains and can be connected to any number of antennas. Also, while the UE 116 is illustrated as being configured as a mobile, or cellular, phone, the UE can be configured to operate as other types of mobile or stationary devices. Figure 3

[0053] Figure 4 ​An exemplary massive MIMO system 400 according to an embodiment of this disclosure is illustrated. Massive MIMO systems typically operate in TDD mode, where the DL and UL operate in different time slots having the same carrier frequency. By operating under TDD, the base station ( For example gNB 102) can be from UE ( For example CSI is collected during uplink transmissions of UE 116, and the CSI is used to assist in multi-user interference suppression via precoding in downlink transmissions to the UE. This can be attributed to the reciprocity characteristics of the RF channel.

[0054] Figure 5A and Figure 5B Examples of a partially connected hybrid MIMO TX system 500 and a partially connected hybrid MIMO RX system 501 according to embodiments of the present disclosure are shown respectively. The digital portion of the system has N DACs and N ADCs, each connected to an analog beamformer having M antenna elements.

[0055] In the Hybrid TX System 500, the DAC generates an analog signal at a certain intermediate frequency (IF). The IF output passes through a filter and gain stage, and is then up-converted to RF. At the analog beamformer, the signal is split into... M The signal is transmitted via an antenna after passing through a variable gain amplifier (VGA) and a phase shifter, as well as the main PA. Similarly, in the hybrid RX system 501, the signal received over the air (OTA) from the antenna passes through a low-noise amplifier (LNA), then through a VGA and a phase shifter. These signals are combined before being down-converted from RF to IF, where additional circuitry may be present for additional gain control and filtering before measurement by the ADC.

[0056] In both hybrid MIMO systems, the complexity of reciprocity calibration increases dramatically compared to digital MIMO systems due to the use of multiple RF components in the analog beamformer, such as PAs, LNAs, phase shifters, and filters. N The number of TX / RX chains increased to N M One chain, in which M (This refers to the number of analog chains in each digital chain). To address this issue, this disclosure provides a hierarchical two-step reciprocity calibration method. First, a standard analog beamforming calibration is performed, referred to as Step 1. Then, a reduced-complexity global reciprocity calibration is introduced, referred to as Step 2. In this step, the reciprocity calibration is performed in... N Execute on one port, not on all. N M Execute on each port.

[0057] The layered reciprocity calibration method of the present disclosure is based on a model mixed MIMO system, which has digital TX and RX chains (which can be combined into digital transceivers (TRXs)), each connected to an independent analog TX or RX phased array with antenna elements. Each element in the phased array has a gain from a VGA and a phase from a phase shifter. For the th phased array element of the th TX phased array, the gain and phase are denoted as and , respectively. Similarly, and denote the gain and phase of the th phased array element of the th RX phased array. and The values can contain independently controllable gain and phase components, as well as some natural phase shift and gain.

[0058] The controllable gain and phase components can be controlled to a level of precision determined by the bit resolution of the corresponding VGA or phase shifter, such that there is a finite set of possible weights for the gain and phase, denoted as and , respectively. and denote the value of the gain of each TX and RX analog chain when the th gain value (or gain ID) is selected from the set of all possible values , and and denote the value of the phase of each TX and RX analog chain when the th phase value (or phase ID) is selected from the set of all possible values . A set of M gain and phase settings corresponds to a beam. For example, ={0、10、20、30} and ={10、11、12、9} may denote a beam in the codebook with i = 1, where M=4 is the number of analog antenna elements. Each element in the set corresponds to an antenna element in the beamformer, as well as the phase ID and gain ID used to construct the beam. These settings are chosen in order to create a particular ideal array response. The analog beamformer can store the settings for B reprogrammable beams in on-board memory for fast access and switching.

[0059] In step 1 of the hierarchical reciprocity calibration, each analog beamformer performs over-the-air (OTA) beamforming calibration to measure the array response. The phase shift and gain settings of each TX and RX chain are stored in a first table of the beamformer memory as beamforming calibration settings. This is typically a one-time calibration that can be done at manufacturing time.

[0060] Figure 6A and Figure 6B Examples of OTA beamforming calibration procedures for TX beamformers 600 and for RX beamformers 601 according to embodiments of the disclosure are shown in FIGS. 6 and 7, respectively. Referring to FIG. 6, Figure 6A , one of the antenna elements of the analog beamformer subarray is selected as a reference node for calibration. The receiver is then aimed at the subarray placement. The responses are measured pairwise through each antenna element and compared to the reference element. After synthesizing the measurement results, the phase shift value for each element that maximizes or minimizes the synthesized value can be determined, thereby aligning the phase shift of each element in the beamformer. Similarly, for RX beamformers 601, the RX synthesis value from the analog beamformer is measured using a transmitter aimed at, pairwise aligning the RX paths.

[0061] Using the first analog subarray / beamformer As an example, the first TX chain element may be selected as the reference node, with reference phase ID . The reference node element has a response . For each other element in the subarray of size M , the K phase ID values are iterated, and the phase ID that minimizes the aimed response of each element is found. This procedure can also be expressed as . For a given beam codebook of B beams, each antenna element obtains a beam calibration phase offset based on the learned values . Similarly, a gain offset calibration is performed on the codebook. These values are stored in the first beamformer table.

[0062] In step 2 of the hierarchical reciprocity calibration, global reciprocity calibration is performed using a calibration network that connects the reference node of the analog beamformer to a calibration transceiver, That is using the calibration receiver to measure all the reference TX nodes and the calibration transmitter to measure all the reference RX nodes. The phase shifters and VGAs are adjusted to align and match all the TX branches and RX branches, respectively, that is, each TX subarray is aligned with the corresponding RX subarray Alignment. The gain and phase settings from the first beamformer table are proportionally scaled by phase shift and gain variation. The adjusted phase shift and gain values are stored in the second beamformer table.

[0063] Figure 7A and Figure 7B Examples of global reciprocity calibration for TX system 700 and RX system 701, respectively, according to embodiments of the present disclosure are shown. Referring to Figure 7A , TX reciprocity calibration measurements are performed by probing and measuring the reference node of each subarray using a common calibration receiver. Similarly, in Figure 7B , RX reciprocity calibration measurements are performed by probing the reference RX path through the reference node of each subarray using a common calibration transmitter. After measuring the difference in phase response between each TX reference node and each RX reference node, the calibration values can be determined and applied to the first beamformer table, creating a second beamformer table. In some embodiments, the second beamformer table can be stored as an update to the first beamformer table, that is, only a single beamformer table can be stored.

[0064] Using the first analog subarray / beamformer For example, the calibration network is used to measure the reciprocity error on the reference node (in this example, j = 1). This can be represented as The angle of can be used to update the phase shift values of the first beamformer table by offsetting the TX or RX phase shift settings by the corresponding amount. Similarly, the magnitude of can be used to update the gain values of the first beamformer table.

[0065] According to the above embodiments, during normal operation, the base station will use the second beamformer table from the beam codebook of each beamformer to set the analog beams. Due to the natural drift in the phase relationship between components, the codebook based on the second beamformer table can be used for a period of time before it needs to be updated. After this period of time has elapsed, step 2 can be repeated to update the second beamformer table again.

[0066] An example of the first and second beamformer tables for a given analog subarray / beamformer is shown below. After step 1, Table 1 is populated, where the phase shifter and VGA settings shown in each table cell represent all Ma set of settings for one element to produce the required TX and RX beam patterns for the corresponding beam index, that is, Table 1 represents the beam codebook for one analog subarray / beamformer after the OTA beamformer calibration at Step 1. After Step 1, each beam index in the TX and RX parts of the table produces a similar pattern, but there can be phase and gain offsets relative to each other (interchangeability errors). In Step 2, these offsets are learned and applied to Table 1, creating Table 2, that is, Table 2 represents the beam codebook for the analog subarray / beamformer after the interchangeability calibration at Step 2. That is

[0067] Table 1

[0068] Table 2

[0069] Figure 8 An exemplary process 800 for hierarchical interchangeability calibration for a hybrid MIMO system according to embodiments of the present disclosure is shown. First, analog beamforming calibration is done to create Table 1. The relative beamforming weights within the analog beamformer do not typically change, so this process does not typically need to be repeated. At deployment of the BS, interchangeability calibration needs to be performed repeatedly every so often, typically in units of minutes. The interchangeability calibration of Step 2 can drift over time due to natural offsets due to temperature changes and other factors.

[0070] Figure 9 An exemplary block diagram of a hybrid MIMO system 900 with hierarchical interchangeability calibration according to embodiments of the present disclosure is shown. There are N digital TRX ports connected to the modem for transmitting and receiving IQ data. These TRX ports are each also connected to a corresponding analog beamformer with M N ports. In Step 1 and Step 2, one port is used as a reference node. Each analog beamformer also contains a table called a beam codebook that contains settings for one element to produce the required TX and RX beam patterns for the corresponding beam index. B ​The phase shift value for each element of a predetermined beam. The modem can select which beam to use at any given time and can overwrite the beam codebook through a "codebook table update" block within the modem. The reference port of each analog beamformer is connected to a calibration network that is also connected to a digital calibration TRX port that is connected to the modem. The modem will periodically probe each TX and RX on each reference port on the analog beamformer using the calibration TRX port. Based on the results, an update to the codebook can be calculated and stored back into the beam codebook on each analog beamformer.

[0071] Various embodiments of the present disclosure incorporate the above-described hierarchical reciprocity calibration into different possible implementations of the hybrid MIMO architecture. In these embodiments, all possible permutations of components that can include TX and RX chains can be included as well as any common transmitter / receiver architecture. This includes systems that are direct RF without an IF to RF conversion with an LO. This also includes systems with DACs and ADCs for real and imaginary components of the baseband waveform where the LOs for the real and imaginary components of the baseband waveform are 90 degrees apart.

[0072] Figure 10 An exemplary hybrid MIMO system 1000 according to embodiments of the present disclosure is shown. The hybrid MIMO system 1000 contains a single larger PA in the TX chain before the analog beamformer instead of a PA for each antenna element for each TX beamformer. Likewise, for the RX portion of the hybrid MIMO system 1000, each RX chain can have a single LNA after the analog beamformer.

[0073] Figure 11A And Figure 11B Examples of global TX reciprocity calibration and global RX reciprocity calibration for the hybrid MIMO system 1000 according to embodiments of the present disclosure are shown. The calibration steps are performed the same as the embodiments described above. In Figure 11A Step 2 of the calibration process is shown in which a single reference element from each subarray is measured by the calibration receiver. Figure 11B The corresponding process for the receiver architecture is shown in which one reference element from each subarray is probed by the calibration transmitter.

[0074] In another embodiment, the TX and RX branches share a common phase shifter and VGA circuit. In another embodiment, each analog beamformer has additional circuitry connected to each TRX chain. This is referred to as a fully connected hybrid beamformer. In another embodiment, the step 1 codebook is measured using a non-OTA method such as a dedicated circuit or instrument such as a vector network analyzer (VNA). In another embodiment, the calibration values from step 2 are not applied to the table 1 codebook to create table 2. Instead, the calibration values are maintained separately as digital calibration weights.

[0075] Figure 12 An exemplary process 1200 for performing hierarchical global reciprocity calibration in a hybrid MIMO system is shown in accordance with various embodiments of the present disclosure. Figure 12 The process 1200 in FIG. 12 is performed by a device equipped with a hybrid MIMO system including a first number (N) of digital transceiver chains, N a second number (M) of analog beamformers (each analog beamformer is operably coupled to a respective one of the digital transceiver chains), a calibration transceiver, and a processor. Each analog beamformer includes a second number (M) of analog transmitter (TX) chains and M a second number (M) of analog receiver (RX) chains, wherein one of the analog RX chains is an RX reference node and one of the analog TX chains is a TX reference node; and a memory operably coupled to the analog TX chains and the analog RX chains and configured to store beam definitions. The calibration transceiver is operably coupled to the TX reference node and the RX reference node of each analog beamformer. The processor is operably coupled to the calibration transceiver, the digital transceiver chains, and the analog beamformers. Figure 12 The process 1200 in FIG. 12 can be performed by a 5G / NR base station (e.g., gNB 102) or any other suitable wireless communication device Example As (e.g., 6G and beyond base stations).

[0076] The process 1200 begins at step 1205, where for each analog beamformer, the device measures a TX phase response and a TX magnitude response of the TX reference node and a RX phase response and a RX magnitude response of the RX reference node using the corresponding digital transceiver chain and the calibration transceiver. In some embodiments, this is done by transmitting a probe signal to each RX reference node using the calibration transceiver to generate the corresponding RX phase response at the corresponding digital transceiver chain and receiving a probe signal from each TX reference node using the calibration transceiver that is transmitted from the corresponding digital transceiver chain to generate the corresponding TX phase response.

[0077] Next, the apparatus determines reciprocity calibration for each analog beamformer based on a phase difference between the TX and RX phase responses and an amplitude difference between the TX and RX amplitude responses (step 1210). In some embodiments, each analog TX chain and each analog RX chain includes a VGA and a phase shifter, and each beam definition includes a gain setting for the VGA and a phase shift setting for the phase shifter of each analog TX chain or each analog RX chain. At step 1210, the apparatus can determine a phase shift offset that minimizes the phase difference between the TX and RX phase responses and a gain offset that minimizes the amplitude difference between the TX and RX amplitude responses as the reciprocity calibration.

[0078] The apparatus then applies the reciprocity calibration for each analog beamformer to the stored beam definition for that beamformer to correct for the phase and amplitude differences (step 1215). For a beam definition that includes settings for an analog TX chain or a beam definition that includes settings for an analog RX chain, the apparatus can apply the phase shift offset to each phase shift setting and the gain offset to each gain setting as the reciprocity calibration.

[0079] The analog beamformer can then apply a selected one of the stored beam definitions to the analog TX chains to form a TX beam or to the analog RX chains to form an RX beam. The steps of process 1200 can be repeated periodically to update the stored beam definitions as the reciprocity calibration drifts.

[0080] In some embodiments, the beam definitions are initially generated based on over-the-air beam calibration such that, for each analog beamformer, an initial TX phase response for each analog TX chain other than a TX reference node is aligned with an initial TX phase response for the TX reference node, the initial TX phase response is measured at an aim receiver aimed at a location of the TX reference node, and an initial RX phase response for each analog RX chain other than an RX reference node is aligned with an initial RX phase response for the RX reference node, the initial RX phase response is measured based on a transmission from an aim transmitter aimed at a location of the RX reference node.

[0081] The above flowcharts illustrate exemplary methods or processes that can be implemented in accordance with the principles of the disclosure, and various changes could be made to the methods or processes illustrated in the flowcharts. For example, although illustrated as a series of steps, various steps could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, various steps could be omitted or replaced by other steps.

[0082] Although the present disclosure has been described with an exemplary embodiment, various changes and modifications can be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read in the limitations of any particular embodiments. The scope of the patent subject matter is defined by the claims.

[0083] Figure 13 a block diagram illustrating a structure of a terminal (or a user equipment) according to various embodiments of the disclosure; and

[0084] As Figure 13 illustrated, the UE according to an embodiment can include a transceiver 1310, a memory 1320, and a processor 1330. The transceiver 1310, the memory 1320, and the processor 1330 of the UE can operate according to the communication method of the UE described above. However, the components of the UE are not limited thereto. For example, the UE can include more or less components than those described above. In addition, the processor 1330, the transceiver 1310, and the memory 1320 can be implemented as a single chip. In addition, the processor 1330 can include at least one processor. Furthermore, Figure 13 the UE of Figure 1 the UE 111 to 116 of Figure 4 the UE 116 of

[0085] The transceiver 1310 is collectively referred to as a UE receiver and a UE transmitter, and can transmit / receive a signal to / from a base station or a network entity. The signal transmitted to or received from the base station or the network entity can include control information and data. The transceiver 1310 can include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for low-noise amplifying and down-converting a frequency of a received signal. However, this is only an example of the transceiver 1310, and the components of the transceiver 1310 are not limited to the RF transmitter and the RF receiver.

[0086] In addition, the transceiver 1310 can receive and output a signal to the processor 1330 through a wireless channel, and transmit a signal output from the processor 1330 through a wireless channel.

[0087] The memory 1320 can store programs and data required for the operation of the UE. In addition, the memory 1320 can store control information or data included in a signal obtained by the UE. The memory 1320 can be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0088] The processor 1330 can control a series of processes so that the UE operates as described above. For example, the transceiver 1310 can receive a data signal including a control signal transmitted by a base station or a network entity, and the processor 1330 can determine a result of receiving the control signal and the data signal transmitted by the base station or the network entity.

[0089] Figure 14 A block diagram illustrating a structure of a base station according to various embodiments of the disclosure is shown.

[0090] As Figure 14 indicated, the base station according to an embodiment can include a transceiver 1410, a memory 1420, and a processor 1430. The transceiver 1410, the memory 1420, and the processor 1430 of the base station can operate according to the communication method of the base station described above. However, the components of the base station are not limited thereto. For example, the base station can include more or less components than the above-described components. In addition, the processor 1430, the transceiver 1410, and the memory 1420 can be implemented as a single chip. In addition, the processor 1430 can include at least one processor. Furthermore, Figure 14 the base station of Figure 1 FIGS. 1 to 3 corresponds to the BS 102 to 103 or Figure 4 the BS 102 of FIG. 4.

[0091] The transceiver 1410 collectively refers to a base station receiver and a base station transmitter, and can transmit / receive a signal to / from a terminal (UE) or a network entity. The signal transmitted to or received from the terminal or the network entity can include control information and data. The transceiver 1410 can include an RF transmitter for up-converting and amplifying the frequency of a transmission signal, and an RF receiver for low-noise amplifying and down-converting the frequency of a reception signal. However, this is only an example of the transceiver 1410, and the components of the transceiver 1410 are not limited to the RF transmitter and the RF receiver.

[0092] In addition, the transceiver 1410 can receive and output a signal to the processor 1430 through a wireless channel, and transmit a signal output from the processor 1430 through a wireless channel.

[0093] The memory 1420 can store programs and data required for the operation of the base station. In addition, the memory 1420 can store control information or data included in a signal obtained by the base station. The memory 1420 can be a storage medium such as a read-only memory (ROM), a random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0094] The processor 1430 can control a series of processes so that the base station operates as described above. For example, the transceiver 1410 can receive a data signal including a control signal transmitted by the terminal, and the processor 1430 can determine a result of receiving the control signal and the data signal transmitted by the terminal.

[0095] The method according to the embodiments described in the claims or the detailed description of the present disclosure can be implemented in hardware, software, or a combination of hardware and software.

[0096] When the electrical structure and method are implemented in software, a computer-readable recording medium having one or more programs (software modules) recorded thereon can be provided. The one or more programs recorded on the computer-readable recording medium are configured to be executable by one or more processors in an electronic device. The one or more programs include instructions for executing the methods according to the embodiments described in the claims or the detailed description of the present disclosure.

[0097] The programs (e.g., software modules or software) can be stored in random access memory (RAM), non-volatile memory including a flash memory, read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), a magnetic disc storage device, an optical disc-ROM (CD-ROM), a digital versatile disc (DVD), another type of optical storage device, or a magnetic cassette. Alternatively, the programs can be stored in a memory system including a combination of some or all of the foregoing memory devices. In addition, each memory device can include a plurality of.

[0098] The programs can also be stored in an attachable storage device that is accessible through a communication network such as the Internet, an intranet, a local area network (LAN), a wireless LAN (WLAN), or a storage area network (SAN), or a combination thereof. The storage device can be connected to the device according to the embodiments of the present disclosure through an external port. Another storage device on the communication network can also be connected to the device that executes the embodiments of the present disclosure.

[0099] In the foregoing embodiments of the present disclosure, elements included in the present disclosure are expressed in singular or plural form according to the embodiments. However, the singular or plural form is appropriately selected for the convenience of explanation, and the present disclosure is not limited thereto. Therefore, an element expressed in plural form can also be configured as a single element, and an element expressed in singular form can also be configured as a plurality of elements.

[0100] Although the drawings illustrate various examples, the application can be used in various ways. For example, the user devices can include any number of each component in any arrangement. In general, the drawings are not limiting of the scope of the disclosure to any particular configuration or arrangement.

[0101] At least some of the example embodiments described herein can be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as "component," "module," or "unit" used herein can include, but are not limited to, hardware devices such as circuits in the form of discrete or integrated components, field-programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs) that perform certain tasks or provide associated functionality. In some embodiments, the described elements can be configured to reside on a tangible, persistent, addressable storage medium and to execute on one or more processors. In some embodiments, these functional elements include, for example, components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules, and units discussed herein, such features can be combined into fewer elements or divided into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that features described as being in combination can be combined in any suitable combination. In particular, features of any one example embodiment can be combined with features of any other embodiment, as appropriate, unless such combinations are mutually exclusive. Throughout this specification, the term "comprising" or "comprises" means including the specified component but not to the exclusion of the presence of other components.

[0102] Note that references to documents and literature in this application are hereby incorporated by reference in their entirety for all purposes.

[0103] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all of the steps of any method or process so disclosed can be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0104] Unless specifically stated otherwise, each feature disclosed in the specification, including any accompanying claims, abstract, and drawings, can be replaced by alternative features that serve the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed in the specification is one example only of a generic series of equivalent or similar features.

[0105] The present application is not restricted to the details of the foregoing embodiment. The present application extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0106] Any of the above variant embodiments can be used independently or in combination with at least one other variant embodiment. The above flowcharts illustrate example methods that can be implemented in accordance with the principles of the present disclosure, and various changes can be made to the methods illustrated in the flowcharts herein. For example, while shown as a series of steps, various steps in each figure could overlap, occur in parallel, occur in a different order, or occur multiple times. In another example, steps can be omitted or replaced by other steps.

[0107] While the present disclosure has been described with respect to exemplary embodiments, various changes and modifications can be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read in the limitations of any specific embodiment described.

[0108] The description of embodiments having several components in communication with each other do not imply that all such components are required. On the contrary, various optional components are described for illustrating various possible embodiments of the present disclosure.

[0109] Where a single device or article is described herein, it will be apparent that more than one device / article (whether or not they cooperate) can be used in place of a single device / article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be apparent that a single device / article can be used in place of the more than one device or article or a different number of devices / articles can be used instead of the shown number of devices or programs. The functionality and / or the features of a device can be performed by separate devices or programs that are described as being integrated into a single device or program. Accordingly, other embodiments of the present disclosure are within the scope of the following claims.

[0110] This specification describes a method and apparatus for selecting a selective security mode for application of selective security and for selective security flow management for a user equipment (UE) under mobility conditions. In addition, this specification also describes a method and apparatus for selective security flow management during handover. The steps shown are intended to explain the embodiments shown and it is contemplated that ongoing technological developments will change the manner in which particular functions are performed. The examples presented herein are intended to be illustrative only and not limiting. In addition, for ease of description, the boundaries of the functional building blocks have been arbitrarily defined herein. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. Alternatives (including equivalents, extensions, variations, deviations, etc.) of the disclosed implementations are also included. Such alternatives are within the scope and spirit of the disclosed embodiments. Furthermore, "comprise," "have," "contain," and "include" and other similar forms are intended to be open-ended, as they are used to describe the presence of stated elements, features, components, or steps, but not to preclude the presence or addition of one or more other elements, features, components, steps, acts, or groups thereof. It is also noted that, unless otherwise specified, "a" or "an" shall not be construed to mean "one and only one" or "exactly one," but rather "one or more."

[0111] While the present disclosure has been described with an example embodiment, various changes and modifications can be suggested to one skilled in the art. It is intended that the present disclosure encompass such changes and modifications as fall within the scope of the appended claims. None of the description in this application should be read in the alternative unless otherwise explicitly stated. The scope of the patent subject matter is defined by the claims.

Claims

1. An apparatus for hybrid multiple-input multiple-output (MIMO) systems, comprising: a first number N of digital transceiver chains; N analog beamformers, each coupled with a respective one of the digital transceiver chains and comprising: a second number M of analog transmitter (TX) chains and M analog receiver (RX) chains, wherein one of the analog RX chains is an RX reference node and one of the analog TX chains is a TX reference node, and a memory coupled with the analog TX chains and the analog RX chains and configured to store beam definitions; a calibration transceiver coupled with the TX reference node and the RX reference node of each analog beamformer; and a processor coupled with the calibration transceiver, the digital transceiver chains, and the analog beamformers, the processor configured to, for each analog beamformer: measure, using a corresponding digital transceiver chain and the calibration transceiver, a TX phase response and a TX magnitude response of the TX reference node and an RX phase response and an RX magnitude response of the RX reference node, determine reciprocity calibration based on a phase difference between the TX phase response and the RX phase response and a magnitude difference between the TX magnitude response and the RX magnitude response, and apply the reciprocity calibration to the beam definitions to correct for the phase difference and the magnitude difference.

2. The apparatus of claim 1, wherein, the calibration transceiver is configured to: transmit a probe signal to each RX reference node to generate a corresponding RX phase response at a corresponding digital transceiver chain, and receive, from each TX reference node, a probe signal transmitted from a corresponding digital transceiver chain to generate a corresponding TX phase response.

3. The apparatus of claim 1, wherein: each analog TX chain and each analog RX chain comprises a variable gain amplifier (VGA) and a phase shifter, and each beam definition comprises a gain setting of the VGA and a phase shift setting of the phase shifter of each analog TX chain or each analog RX chain.

4. The apparatus of claim 3, wherein, the processor is further configured to, for each analog beamformer: determine a phase shift offset that minimizes a phase difference between the TX phase response and the RX phase response, determine a gain offset that minimizes a magnitude difference between the TX magnitude response and the RX magnitude response, and apply, as the reciprocity calibration, the phase shift offset to each phase shift setting and the gain offset to each gain setting for the beam definition comprising settings of the analog TX chains or the beam definition comprising settings of the analog RX chains.

5. The apparatus of claim 1, wherein, the beam definitions are initially generated based on over-the-air beam calibration such that, for each analog beamformer: an initial TX phase response of each analog TX chain, other than the TX reference node, is aligned with an initial TX phase response of the TX reference node, the initial TX phase responses measured at a boresight receiver positioned at a boresight alignment with the TX reference node, and an initial RX phase response of each analog RX chain, other than the RX reference node, is aligned with an initial RX phase response of the RX reference node, the initial RX phase responses measured at a boresight receiver positioned at a boresight alignment with the RX reference node. In addition to the RX reference node, an initial RX phase response of each analog RX chain is aligned with an initial RX phase response of the RX reference node, the initial RX phase response being measured based on a transmission from a boresight transmitter that is aimed at a location of the RX reference node.

6. The apparatus of claim 1, wherein, The processor is further configured to periodically determine and apply the reciprocity calibration.

7. The apparatus of claim 1, wherein, The analog beamformer is configured to apply a selected one of the beam definitions to the analog TX chains to form a TX beam or to the analog RX chains to form an RX beam.

8. A method performed by an apparatus for hybrid multiple-input multiple-output (MIMO) systems, the system including a first number N of digital transceiver chains, N analog beamformers, and a calibration transceiver, the method comprising: For each analog beamformer, measuring a transmitter (TX) phase response and a TX magnitude response of a TX reference node of the analog beamformer and a receiver (RX) phase response and an RX magnitude response of an RX reference node of the analog beamformer using a corresponding digital transceiver chain and the calibration transceiver, wherein each analog beamformer includes a second number M of analog TX chains and M analog RX chains, one of the analog RX chains being the RX reference node and one of the analog TX chains being the TX reference node; determining a reciprocity calibration for each analog beamformer based on a phase difference between the TX phase response and the RX phase response and a magnitude difference between the TX magnitude response and the RX magnitude response; and applying the reciprocity calibration to stored beam definitions of each analog beamformer to correct for the phase difference and the magnitude difference.

9. The method of claim 8, further comprising: transmitting, using the calibration transceiver, a probe signal to each RX reference node to generate a corresponding RX phase response at a corresponding digital transceiver chain; and receiving, by the calibration transceiver, a probe signal transmitted from a corresponding digital transceiver chain from each TX reference node to generate a corresponding TX phase response.

10. The method of claim 8, wherein: each analog TX chain and each analog RX chain includes a variable gain amplifier (VGA) and a phase shifter, and each beam definition includes a gain setting of the VGA and a phase shift setting of the phase shifter of each analog TX chain or each analog RX chain.

11. The method of claim 10, further comprising, for each beamformer: determining a phase shift offset that minimizes a phase difference between the TX phase response and the RX phase response, determining a gain offset that minimizes a magnitude difference between the TX magnitude response and the RX magnitude response, and applying the phase shift offset to each phase shift setting and the gain offset to each gain setting of the beam definition that includes settings of the analog TX chains or the beam definition that includes settings of the analog RX chains as the reciprocity calibration. The beam definitions are initially generated based on an over-the-air beam calibration such that, for each analog beamformer:

12. The method of claim 8, wherein, ​ In addition to the TX reference node, an initial TX phase response of each analog TX chain is aligned with an initial TX phase response of the TX reference node, the initial TX phase response being measured at an aim receiver aimed at a location of the TX reference node, and In addition to the RX reference node, an initial RX phase response of each analog RX chain is aligned with an initial RX phase response of the RX reference node, the initial RX phase response being measured based on a transmission from an aim transmitter aimed at a location of the RX reference node.

13. The method of claim 8, further comprising periodically determining and applying the reciprocity calibration.

14. The method of claim 8, further comprising: For each analog beamformer, applying a selected one of the beam definitions to the analog TX chains to form a TX beam or to the analog RX chains to form an RX beam.

15. A non-transitory computer-readable medium configured to store instructions that, when executed by a processor, cause a hybrid multiple-input multiple-output (MIMO) system comprising a first number N of digital transceiver chains, N analog beamformers, and a calibration transceiver: For each analog beamformer, the transmitter TX phase response and the TX amplitude response of a TX reference node of the analog beamformer and the receiver RX phase response and the RX amplitude response of a RX reference node of the analog beamformer are measured using the corresponding digital transceiver chain and the calibration transceiver, wherein each analog beamformer comprising a second number M of analog TX chains and M analog RX chains, one of the analog RX chains being the RX reference node and one of the analog TX chains being the TX reference node; determining a reciprocity calibration for each analog beamformer based on a phase difference between the TX phase response and the RX phase response and an amplitude difference between the TX amplitude response and the RX amplitude response; and applying the reciprocity calibration to stored beam definitions of each analog beamformer to correct for the phase difference and the amplitude difference.

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