Methods and apparatus for user equipment sub-chain beam codebook design and operation

Abstract

A user equipment (UE) is configured to change a number of chains in uplink or downlink communication with a base station (BS). The UE includes a processor coupled to a transceiver. The processor is configured to identify full-chain beams for downlink reception based on a beam sweep, determine a number of active chains for uplink transmission, and determine sub-chain uplink transmission beams.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 115,865, filed November 19, 2020, and U.S. Patent Application No. 17 / 445,583, filed August 20, 2021. The contents of the aforementioned patent documents are incorporated herein by reference. Technical Field

[0003] This disclosure relates to electronic devices and methods for designing user equipment beamcodebooks, and more specifically, to electronic devices and methods for designing sub-chain beamcodebooks. Background Technology

[0004] Wireless communication is one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services has exceeded 5 billion and continues to grow rapidly. The demand for wireless data traffic is growing rapidly due to the increasing popularity of smartphones and other mobile data devices (such as tablets, laptops, netbooks, e-book readers, and machine-type devices) among consumers and businesses. To meet this rapid growth in mobile data traffic and support new applications and deployments, improving the efficiency and coverage of radio interfaces is crucial. Summary of the Invention

[0005] Embodiments of this disclosure provide methods and apparatus for site-specific and dynamic UE beamcodebook design.

[0006] In one embodiment, a user equipment (UE) is provided. The UE includes an antenna and a transceiver configured to communicate with a base station (BS) via a wireless communication medium. The UE also includes a processor coupled to the transceiver. The processor is configured to: identify full-chain beams for downlink reception based on beam scanning; determine the number of active chains for uplink transmission; and determine sub-chain uplink transmission beams.

[0007] In another embodiment, a method is provided. The method includes identifying full-chain beams for downlink reception based on beam scanning. The method also includes determining the number of active chains for uplink transmission. The method further includes determining sub-chain uplink transmission beams.

[0008] Other technical features will be apparent to those skilled in the art from the following figures, description and claims.

[0009] Before proceeding with the detailed implementation below, it may be advantageous to define certain words and phrases used in this patent document. The term “coupled” and its derivatives refer to any direct or indirect communication between two or more elements, regardless of whether these elements are physically in contact with each other. The terms “transmit,” “receive,” and “communicate,” and their derivatives include both direct and indirect communication. The terms “comprise” and “include,” and their derivatives, mean unrestricted inclusion. The term “or” is inclusive, meaning and / or. The phrase “associated with” and its derivatives refer to including, being included, interconnected with, containing, being contained, connected to or connected to, coupled to or coupled with, able to communicate with, cooperate with, intertwine, juxtapose, proximate, combined with or combined with, having, possessing the properties of, having a relationship to, or having a relationship with, etc. The term “controller” refers to any device, system, or part thereof that controls at least one operation. Such a controller may be implemented in hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller may be centralized or distributed, local or remote. When used with a list of items, the phrase "at least one of..." means that different combinations of one or more of the listed items may be used, and it may be necessary to use only one item from the list. 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.

[0010] Furthermore, the various functions described below can be implemented or supported by one or more computer programs, each of which is formed by computer-readable program code and contained in a computer-readable medium. The terms "application" and "program" refer to one or more computer programs, software components, instruction sets, procedures, functions, objects, classes, instances, associated data, or portions thereof suitable for implementation in appropriate 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 accessible by a computer, such as read-only memory (ROM), random access memory (RAM), hard disk drives, compact discs (CDs), digital video discs (DVDs), or any other type of storage. "Non-transitory" computer-readable media excludes wired, wireless, optical, or other communication links that transmit temporary electrical or other signals. Non-transitory computer-readable media includes media that can permanently store data and media that can store data and be overwritten later, such as rewritable optical discs or erasable memory devices.

[0011] Definitions of other specific words and phrases are also provided in this patent document. Those skilled in the art will understand that, in many (if not most) cases, such definitions apply to the prior and future use of the words and phrases defined in this way. Attached Figure Description

[0012] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, wherein like reference numerals denote like parts:

[0013] Figure 1 An example wireless network according to an embodiment of the present disclosure is shown;

[0014] Figure 2 An example gNB according to an embodiment of this disclosure is shown;

[0015] Figure 3 An example UE according to an embodiment of the present disclosure is shown;

[0016] Figure 4a A high-level diagram of an orthogonal frequency division multiple access transmission path according to an embodiment of the present disclosure is shown;

[0017] Figure 4b A high-level diagram of an orthogonal frequency division multiple access (OFDM) receiving path according to an embodiment of the present disclosure is shown;

[0018] Figure 5 An example antenna according to an embodiment of the present disclosure is shown;

[0019] Figure 6 An example antenna configuration on a mobile terminal according to an embodiment of the present disclosure is shown;

[0020] Figure 7 An example rollback procedure for a terminal according to an embodiment of this disclosure is shown;

[0021] Figure 8 and Figure 9 Examples of downlink-uplink correspondences with different numbers of chains according to embodiments of the present disclosure are shown;

[0022] Figure 10 , Figure 11 and Figure 12 Design metrics according to embodiments of the present disclosure are illustrated;

[0023] Figure 13 An example process for codebook selection based on inter-link beam correspondence according to this disclosure is shown;

[0024] Figure 14 An example procedure for codebook selection based on inter-link beam correspondence and beam measurement according to this disclosure is shown;

[0025] Figure 15 An example process for codebook selection based on terminal beam scanning timing according to this disclosure is shown;

[0026] Figure 16 An example process for scheme selection based on precoding matrix index feedback configuration according to this disclosure is shown;

[0027] Figure 17 An example process for temperature-dependent subchain / full-chain operation according to this disclosure is shown;

[0028] Figure 18 An example process for temperature-dependent subchain operation according to this disclosure is shown;

[0029] Figure 19 An example process for subchain operations based on various factors according to this disclosure is shown;

[0030] Figure 20 This illustrates an example process for reducing the antenna duty cycle for an Rx beam according to this disclosure; and

[0031] Figure 21 An example process for reducing the antenna duty cycle according to this disclosure is shown. Detailed Implementation

[0032] The following discussion Figures 1 to 21 The various embodiments used to describe the principles of this disclosure in this patent document are merely exemplary and should not be construed in any way as limiting the scope of this disclosure. Those skilled in the art will understand that the principles of this disclosure can be implemented in any suitably arranged system or device.

[0033] From the following detailed description, aspects, features, and advantages of this disclosure will become clear only by illustrating several specific embodiments and implementations (including the best mode for carrying out this disclosure). This disclosure is also capable of including other and different embodiments, and several details thereof may be modified in various obvious ways without departing from the spirit and scope of this disclosure. Therefore, the drawings and description are to be considered illustrative in nature and not restrictive. In the drawings, this disclosure is shown by way of example rather than limitation.

[0034] To meet the increased demand for wireless data traffic since the deployment of 4G communication systems, and to support various vertical applications, 5G communication systems have been developed and are currently being deployed. The basic principle of New Radio (NR) in the 3rd Generation Partnership Project (3GPP) is to support beam-specific operation for wireless communication between gNode B (gNB) and User Equipment (UE). Several components exist in the 5G (e.g., fifth-generation) NR specification that can operate efficiently in a beam-specific manner.

[0035] 5G communication systems are considered to be implemented using higher frequency (millimeter wave) bands (such as 28 GHz or 60 GHz bands, or generally, bands above 6 GHz) to achieve higher data rates, or lower frequency bands (such as below 6 GHz) to achieve robust coverage and mobility support. Aspects of this disclosure can be applied to the deployment of 5G communication systems, 6G, or even later versions that can utilize THz frequency bands. To reduce radio wave propagation loss and increase transmission distance, beamforming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive MIMO technologies are discussed in 5G communication systems.

[0036] In addition, in 5G communication systems, development is underway to improve the system network based on advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), and receiver interference cancellation.

[0037] In the following text, for the sake of brevity, both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) are considered as duplexing methods for both DL and UL signaling.

[0038] Although the following exemplary description and embodiments assume orthogonal frequency division multiplexing (OFDM) or orthogonal frequency division multiple access (OFDMA), this disclosure can be extended to other OFDM-based transmission waveforms or multiple access schemes, such as filtered OFDM (F-OFDM).

[0039] This disclosure covers several components that can be used together or in combination with each other, or that can operate as independent solutions.

[0040] The following Figures 1-4b Various embodiments of communication technologies, such as Orthogonal Frequency Division Multiplexing (OFDM) or Orthogonal Frequency Division Multiple Access (OFDMA), are described in wireless communication systems. Figures 1-3 The description does not imply any physical or architectural limitation on the ways in which different embodiments may be implemented. Different embodiments of this disclosure can be implemented in any suitably arranged communication system.

[0041] Figure 1 An example wireless network according to an embodiment of this disclosure is shown. Figure 1 The embodiments of the wireless network shown are for illustrative purposes only. Other embodiments of the wireless network 100 may be used without departing from the scope of this disclosure.

[0042] like Figure 1As shown, the wireless network includes base stations gNB 101, 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).

[0043] gNB 102 provides wireless broadband access to network 130 to a first plurality of user equipments (UEs) within its coverage area 120. 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 (E); UE 113, which may be located in a WiFi hotspot (HS); UE 114, which may be located in a first residence (R); UE 115, which may be located in a second residence (R); and UE 116, which may be a mobile device (M), such as a cellular phone, wireless laptop computer, wireless PDA, etc. gNB 103 provides wireless broadband access to network 130 to a second plurality of UEs within its coverage area 125. 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, LTE, LTE-A, WiMAX, WiFi, or other wireless communication technologies.

[0044] Depending on the network type, the term "base station" or "BS" can refer to any component (or set of components) configured to provide wireless access to a network, such as a transmitting point (TP), a transmitting-receiving point (TRP), an enhanced base station (eNodeB or eNB), a 5G base station (gNB), a macro cell, a femtocell, a WiFi access point (AP), or other wireless-enabled equipment. A base station can provide wireless access according to one or more wireless communication protocols, such as 5G 3GPP New Radio Interface / Access (NR), Long Term Evolution (LTE), LTE-Advanced (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. Furthermore, depending on the network type, the term "user equipment" or "UE" can refer to any component, such as a "mobile station," "subscriber station," "remote terminal," "wireless terminal," "receiving 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 provides wireless access to a BS, whether the UE is a mobile device (such as a mobile phone or smartphone) or is generally considered to be a fixed device (such as a desktop computer or vending machine).

[0045] The dashed lines indicate the approximate extent of coverage areas 120 and 125, which are shown as approximately circular for illustrative and explanatory purposes only. It should be clearly understood that, depending on the configuration of the gNB and variations in the radio environment associated with natural and man-made obstacles, the coverage areas associated with the gNB (such as coverage areas 120 and 125) may have other shapes, including irregular shapes.

[0046] As described in more detail below, one or more of gNB 101, gNB 102, and gNB 103 include a two-dimensional (2D) antenna array as described in embodiments of this disclosure. In some embodiments, one or more of gNB 101, gNB 102, and gNB 103 support codebook design and architecture for systems having 2D antenna arrays.

[0047] As described in more detail below, one or more of UEs 111-116 include circuitry, programming, or a combination thereof for sub-chain beamcodebook design and operation. In some embodiments, one or more of gNBs 101-103 include circuitry, programming, or a combination thereof to facilitate the design and operation of the sub-chain beamcodebook.

[0048] although Figure 1 An example of a wireless network is shown, but more can be found on... Figure 1 Various modifications can be made. For example, the wireless network can include any number of gNBs and any number of UEs in any suitable arrangement. Furthermore, gNB 101 can communicate directly with any number of UEs and provide these UEs with wireless broadband access to network 130. Similarly, each gNB 102-103 can communicate directly with network 130 and provide the UEs with direct wireless broadband access to network 130. Additionally, 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).

[0049] Figure 2 An example gNB 102 according to an embodiment of the present disclosure is shown. Figure 2 The embodiment of gNB 102 shown is for illustrative purposes only, and Figure 1 gNBs 101 and 103 can have the same or similar configurations. However, gNBs come in a wide variety of configurations, and Figure 2 This disclosure is not intended to limit the scope to any particular implementation of gNB.

[0050] like Figure 2As shown, gNB 102 includes multiple antennas 205a-205n, RF transceivers 210a-210n, transmit (TX) processing circuitry 215, and receive (RX) processing circuitry 220. gNB 102 also includes a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0051] RF transceivers 210a-210n receive incoming RF signals, such as signals transmitted by a UE in network 100, from antennas 205a-205n. RF transceivers 210a-210n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to RX processing circuitry 220, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signals. RX processing circuitry 220 sends the processed baseband signal to controller / processor 225 for further processing.

[0052] The TX processing circuit 215 receives analog or digital data (such as voice data, network data, email, or interactive video game data) from the controller / processor 225. The TX processing circuit 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceivers 210a-210n receive the processed baseband or IF signal from the TX processing circuit 215 and up-convert the baseband or IF signal into an RF signal transmitted via antennas 205a-205n.

[0053] 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 RF transceivers 210a-210n, the RX processing circuitry 220, and the TX processing circuitry 215 to receive forward channel signals and transmit reverse channel signals, based on known principles. The controller / processor 225 may also support additional functions, such as more advanced wireless communication functions. That is, the controller / processor 225 may perform BIS processes, such as those performed by a blind interference sensing (BIS) algorithm, and decode the received signal after subtracting the interference signal. The controller / processor 225 may support any of a variety of other functions in the gNB 102. In some embodiments, the controller / processor 225 includes at least one microprocessor or microcontroller.

[0054] In some embodiments, the controller / processor 225 may support beamforming or directional routing operations in which outgoing signals from multiple antennas 205a-205n are weighted differently to effectively direct these outgoing signals in a desired direction. The controller / processor 225 may support any of a variety of other functions in the gNB 102.

[0055] The controller / processor 225 is also capable of executing programs and other processes, such as an operating system, residing in the memory 230. The controller / processor 225 can move data into or out of the memory 230 as needed by the executing process.

[0056] The controller / processor 225 is also capable of sub-chain beamcodebook design and operation, as described in embodiments of this disclosure. In some embodiments, the controller / processor 225 supports communication between entities, such as network RTCs. The controller / processor 225 can move data into or out of memory 230 as needed during execution.

[0057] 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 over a network. Interface 235 can support communication via 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, LTE, or LTE-A), interface 235 can 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, interface 235 can 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. Interface 235 includes any suitable architecture supporting communication via wired or wireless connections, such as Ethernet or RF transceivers.

[0058] Memory 230 is coupled to controller / processor 225. A portion of memory 230 may include RAM, while another portion may include flash memory or other ROM. In some embodiments, multiple instructions, such as a BIS algorithm, are stored in memory 230. The multiple instructions are configured to cause controller / processor 225 to perform the BIS process and decode the received signal after subtracting at least one interference signal determined by the BIS algorithm.

[0059] As described in more detail below, the transmit and receive paths of the gNB 102 (implemented using RF transceivers 210a-210n, TX processing circuitry 215, and / or RX processing circuitry 220) support sub-chain beamcodebook design and operation.

[0060] although Figure 2 An example of gNB 102 is shown, but more can be found on... Figure 2 Various changes can be made. For example, gNB 102 can include any number of Figure 2 Each component is shown. As a specific example, an access point may include multiple interfaces 235, and the controller / processor 225 may support routing functionality for routing data between different network addresses. As another specific example, although shown as a single instance including TX processing circuitry 215 and a single instance including RX processing circuitry 220, gNB102 may include multiple instances of each (such as one instance per RF transceiver). Furthermore, Figure 2 The various components can be combined, further subdivided, or omitted, and additional components can be added as needed.

[0061] Figure 3 An example 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 111-115 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 to any particular implementation of the UE.

[0062] like Figure 3 As shown, UE 116 includes an antenna 305, a radio frequency (RF) transceiver 310, a TX processing circuit 315, a microphone 320, and a receive (RX) processing circuit 325. UE 116 also includes a speaker 330, a processor 340, an input / output (I / O) interface (IF) 345, a touchscreen 350 (or keyboard), a display 355, and memory 360. Memory 360 includes an operating system (OS) 361 and one or more applications 362.

[0063] RF transceiver 310 receives incoming RF signals transmitted by a gNB of network 100 from antenna 305. RF transceiver 310 down-converts the incoming RF signals to generate an intermediate frequency (IF) or baseband signal. The IF or baseband signal is sent to RX processing circuitry 325, which generates a processed baseband signal by filtering, decoding, and / or digitizing the baseband or IF signal. RX processing circuitry 325 sends the processed baseband signal to speaker 330 (e.g., for voice data) or processor 340 for further processing (e.g., for web browsing data).

[0064] The TX processing circuit 315 receives analog or digital voice data from the microphone 320, or other outgoing baseband data (such as network data, email, or interactive video game data) from the processor 340. The TX processing circuit 315 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate a processed baseband or IF signal. The RF transceiver 310 receives the processed baseband or IF signal from the TX processing circuit 315 and up-converts the baseband or IF signal into an RF signal transmitted via the antenna 305.

[0065] Processor 340 may include one or more processors or other processing devices and executes OS 361 stored in memory 360 to control the overall operation of UE 116. For example, processor 340 may control the RF transceiver 310, RX processing circuit 325, and TX processing circuit 315 to receive forward channel signals and transmit reverse channel signals according to known principles. In some embodiments, processor 340 includes at least one microprocessor or microcontroller.

[0066] Processor 340 is also capable of executing other processes and programs residing in memory 360, such as UL transmissions on the uplink channel. Processor 340 can move data into or out of memory 360 as needed for 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 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 laptop computers and handheld computers. I / O interface 345 is the communication path between these accessories and processor 340.

[0067] The processor 340 is also coupled to the touchscreen 350 and the display 355. The operator of the UE 116 can use the touchscreen 350 to input data into the UE 116. The display 355 may be a liquid crystal display, a light-emitting diode display, or other display capable of displaying text (such as from a website) and / or at least limited graphics.

[0068] The memory 360 is coupled to the processor 340. A portion of the memory 360 may include random access memory (RAM), while another portion of the memory 360 may include flash memory or other read-only memory (ROM).

[0069] although Figure 3 An example of UE 116 is shown, but it is possible to modify it. Figure 3 Make various changes. For example, Figure 3The various components can be combined, further subdivided, or omitted, and additional components can be added as needed. As a specific example, 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). Furthermore, although... Figure 3 The UE 116 is shown configured as a mobile phone or smartphone, but the UE can be configured to operate as other types of mobile or fixed devices.

[0070] Figure 4a This is a high-level diagram of the transmit path circuitry. For example, the transmit path circuitry can be used in Orthogonal Frequency Division Multiple Access (OFDMA) communication. Figure 4b This is a high-level diagram of the receive path circuitry. For example, the receive path circuitry can be used in Orthogonal Frequency Division Multiple Access (OFDMA) communication. Figure 4a and Figure 4b In the context of downlink communication, the transmitting path circuitry can be implemented in the base station (gNB) 102 or a relay station, and the receiving path circuitry can be implemented in the user equipment (e.g., Figure 1 The user equipment 116) is implemented in other examples. For uplink communication, the receive path circuit 450 can be implemented in the base station (e.g., Figure 1 This can be implemented in a gNB 102 or a relay station, and the transmission path circuit can be implemented in the user equipment (e.g., Figure 1 Implemented in user equipment 116).

[0071] The transmit path circuitry includes a channel coding and modulation block 405, a serial-to-parallel (S-to-P) block 410, an N-size inverse fast Fourier transform (IFFT) block 415, a parallel-to-serial (P-to-S) block 420, a cyclic prefix addition block 425, and an up-converter (UC) 430. The receive path circuitry includes a down-converter (DC) 455, a cyclic prefix removal block 460, a serial-to-parallel (S-to-P) block 465, an N-size fast Fourier transform (FFT) block 470, a parallel-to-serial (P-to-S) block 475, and a channel decoding and demodulation block 480.

[0072] Figure 4a 400 and Figure 4b At least some of the components in 450 can be implemented in software, while others can be implemented using configurable hardware or a combination of software and configurable hardware. Specifically, note that the FFT and IFFT blocks described in this disclosure can be implemented as configurable software algorithms, where the value of size N can be modified depending on the implementation.

[0073] Furthermore, although this disclosure pertains to embodiments implementing the Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT), this is merely illustrative and should not be construed as limiting the scope of this disclosure. It will be understood that in alternative embodiments of this disclosure, the FFT and IFFT functions can be readily replaced by the Discrete Fourier Transform (DFT) and Inverse Discrete Fourier Transform (IDFT) functions, respectively. It will be understood that for the DFT and IDFT functions, the value of the N variable can be any integer (i.e., 1, 4, 3, 4, etc.), while for the FFT and IFFT functions, the value of the N variable can be any integer power of 2 (i.e., 1, 2, 4, 8, 16, etc.).

[0074] In the transmit path circuit 400, the channel coding and modulation block 405 receives a set of information bits and applies coding (e.g., LDPC coding) and modulation (e.g., Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM)) to the input bits to produce a frequency-domain modulated symbol sequence. The serial-to-parallel block 410 converts (i.e., demultiplexes) the serial data via modulated symbols into parallel data to produce N parallel symbol streams, where N is the IFFT / FFT size used in BS 102 and UE 116. An IFFT block 415 of size N then performs an IFFT operation on the N parallel symbol streams to produce a time-domain output signal. The parallel-to-serial block 420 converts (i.e., multiplexes) the parallel time-domain output symbols from the N-size IFFT block 415 to produce a serial time-domain signal. A cyclic prefix addition block 425 then inserts a cyclic prefix into the time-domain signal. Finally, the upconverter 430 modulates (i.e., upconverts) the output of the added cyclic prefix block 425 to the RF frequency for transmission via the wireless channel. The signal can also be filtered in baseband before being converted to the RF frequency.

[0075] The transmitted RF signal reaches UE 116 after passing through the wireless channel, and the operation opposite to that at gNB 102 is performed. Downconverter 455 downconverts the received signal to the baseband frequency, and cyclic prefix removal block 460 removes the cyclic prefix to generate a serial time-domain baseband signal. Serial-to-parallel block 465 converts the time-domain baseband signal into a parallel time-domain signal. FFT block 470 of size N then performs the FFT algorithm to generate N parallel frequency-domain signals. Parallel-to-serial block 475 converts the parallel frequency-domain signals into a modulated data symbol sequence. Channel decoding and demodulation block 480 demodulates and subsequently decodes the modulated symbols to recover the original input data stream.

[0076] Each of gNBs 101-103 can implement a transmission path similar to that used for transmitting to user equipments 111-116 in the downlink, and a reception path similar to that used for receiving from user equipments 111-116 in the uplink. Similarly, each of user equipments 111-116 can implement a transmission path corresponding to the architecture used for transmitting to gNBs 101-103 in the uplink, and a reception path corresponding to the architecture used for receiving from gNBs 101-103 in the downlink.

[0077] Use cases for 5G communication systems have been identified and described. These use cases can be broadly categorized into three distinct groups. In one example, enhanced mobile broadband (eMBB) was identified as meeting high bit / second requirements with less stringent latency and reliability requirements. In another example, ultra-reliable and low latency (URLL) was identified with less stringent bit / second requirements. In yet another example, massive machine-type communication (mMTC) was identified where the number of devices per square kilometer can be up to 100,000 to 1 million, but reliability / throughput / latency requirements can be less stringent. This scenario may also involve power efficiency requirements, as battery consumption is likely to be minimized as much as possible.

[0078] A communication system comprises a downlink (DL) that transmits signals from a transmitting point, such as a base station (BS) or NodeB, to a user equipment (UE) and an uplink (UL) that transmits signals from the UE to a receiving point, such as a NodeB. A UE, also commonly referred to as a terminal or mobile station, can be fixed or mobile and can be a cellular phone, personal computer device, or automated device. An eNodeB, typically a fixed station, can also be referred to as an access point or other equivalent terms. In LTE systems, a NodeB is typically referred to as an eNodeB.

[0079] In communication systems such as LTE, DL signals can include data signals that transmit information content, control signals that transmit DL control information (DCI), and reference signals (RS), also known as pilot signals. The eNodeB transmits data information through the Physical DL Shared Channel (PDSCH). The eNodeB transmits DCI through the Physical DL Control Channel (PDCCH) or the Enhanced PDCCH (EPDCCH).

[0080] The eNodeB transmits acknowledgment (ACK) messages in response to data block (TB) transmissions from the UE in the Physical Hybrid ARQ Indicator Channel (PHICH). The eNodeB transmits one or more types of RS, including UE Common RS (CRS), Channel State Information (CSI)-RS (CSI-RS), or Demodulated RS (DMRS). CRS is transmitted over the DL system bandwidth (BW) and can be used by the UE to obtain channel estimates for demodulating data or control information or performing measurements. To reduce CRS overhead, the eNodeB can transmit CSI-RS at a lower density in the time and / or frequency domains than CRS. DMRS can be transmitted only in the BW of the corresponding PDSCH or EPDCCH, and the UE can use DMRS to demodulate data or control information in the PDSCH or EPDCCH, respectively. The transmission time interval of the DL channel is called a subframe and can have a duration of, for example, 1 millisecond.

[0081] The DL signal also includes the transmission of logical channels carrying system control information. The BCCH is mapped to a transport channel called the Broadcast Channel (BCH) when the DL signal transmits the Main Information Block (MIB), or to the DL Shared Channel (DL-SCH) when the DL signal transmits the System Information Block (SIB). Most system information is included in different SIBs transmitted using the DL-SCH. The presence of system information on the DL-SCH in a subframe can be indicated by the transmission of the corresponding PDCCH (which transmits codewords with Cyclic Redundancy Check (CRC) scrambled with system information RNTI (SI-RNTI)). Alternatively, scheduling information for SIB transmission can be provided in earlier SIBs, and scheduling information for the first SIB (SIB-1) can be provided by the MIB.

[0082] DL resource allocation is performed in units of subframes and a set of physical resource blocks (PRBs). A transport BW consists of frequency resource elements called resource blocks (RBs). Each RB comprises N... EPDCCH Each subcarrier or resource element (RE) can have a total of 12 REs. An RB (Resource Element) is a unit on a subframe called a PRB. For PDSCH transmission BW, multiple RBs can be allocated to the UE, totaling... One RE.

[0083] UL signals can include data signals for transmitting data information, control signals (UCI) for transmitting UL control information, and UL RS. UL RS includes DMRS and probe RS. The UE only transmits DMRS in the corresponding PUSCH or PUCCH BW. The eNodeB can use DMRS to demodulate data signals or UCI signals. The UE transmits SRS to provide UL CSI to the eNodeB. The UE transmits data information or UCI through the corresponding Physical UL Shared Channel (PUSCH) or Physical UL Control Channel (PUCCH). If the UE needs to transmit data information and UCI in the same UL subframe, the UE can multiplex both in the PUSCH. UCI includes Hybrid Automatic Repeat Request Acknowledgment (HARQ-ACK) information, which indicates a correct (e.g., acknowledgment (ACK)) or incorrect (e.g., negative acknowledgment (NACK)) detection of data TB in PDSCH or a missing (DTX) detection in PDCCH; a scheduling request (SR) indicating whether there is data in the UE's buffer; a rank indicator (RI); and channel state information (CSI) that enables the eNodeB to transmit link-adaptive channel state information for the PDSCH to the UE. In response to the detection of a PDCCH / EPDCCH indicating the release of a semi-persistent PDSCH, the UE also sends a HARQ-ACK message.

[0084] A UL subframe consists of two time slots. Each time slot includes a space for transmitting data information, UCI, DMRS, or SRS. The frequency resource unit (RB) of the UL system BW is one symbol. For the transmission BW, N is allocated to the UE. RB RB, total One RE. For PUCCH, N RB =1. The last subframe symbol can be used to multiplex SRS transmissions from one or more UEs. The number of subframe symbols available for data / UCI / DMRS transmission is Where the last subframe symbol is used to transmit SRS, then N SRS =1, otherwise N SRS =0.

[0085] As the operating band in NR becomes higher, UEs are evolving to accommodate multiple antenna panels, thereby enhancing various aspects of multi-beam operation, such as coverage enhancement, beam failure event minimization, and fast beam switching. Depending on the hardware architecture, each panel on the UE 116 can perform multi-beam operation in a decoupled manner, making it possible for the UE 116 to perform DL / UL operations simultaneously via multiple beam links, each corresponding to a sufficiently reliable channel to communicate independently with the gNB 102. Previous NR specifications only allowed multiple panels on the UE 116 for simultaneous DL reception, or a single panel selection for UL transmission in TDD operations.

[0086] Figure 5 An example antenna block 500 according to an embodiment of the present disclosure is shown. Figure 5 The embodiment of antenna 500 shown is for illustrative purposes only. Figure 5 This disclosure is not intended to limit the scope to any particular implementation of antenna 500. In some embodiments, one or more of gNB 102 or UE 116 include antenna 500. For example, antenna 205 and its associated systems or antenna 305 and one or more of its associated systems may be configured to be identical to antenna 500.

[0087] Version 14 LTE and Version 15 NR support up to 32 CSI-RS antenna ports, enabling eNBs to be equipped with a large number of antenna elements (such as 64 or 128). In this case, multiple antenna elements are mapped onto a single CSI-RS port. For millimeter-wave bands, although the number of antenna elements can be greater for a given form factor, the number of CSI-RS ports (which can correspond to the number of digitally precoded ports) is often limited by hardware constraints (such as the feasibility of installing a large number of ADCs / DACs at millimeter-wave frequencies).

[0088] exist Figure 5 In the example shown, antenna 500 includes an analog phase shifter 505, an analog beamformer (BF) 510, a hybrid BF 515, a digital BF 520, and one or more antenna arrays 525. In this case, a CSI-RS port is mapped to a large number of antenna elements in antenna array 525 that can be controlled by the banks of the analog phase shifter 505. A CSI-RS port can then correspond to a subarray that generates a narrow analog beam through analog beamforming of the analog BF 510. The analog beam can be configured to scan over a wider angular range 530 by changing the banks of the phase shifter 505 across symbols or subframes. The number of subarrays (equal to the number of RF chains) is related to the number of CSI-RS ports N. CSI-PORT Same. Number BF 515 across N CSI-PORTThe analog beams are linearly combined to further increase the precoding gain. Although the analog beams are broadband (and therefore not frequency selective), digital precoding can vary across frequency subbands or resource blocks.

[0089] Because the aforementioned system utilizes multiple analog beams for transmission and reception (where one or a few analog beams are selected from a large number of analog beams, for example, after a training period—performed from time to time), the term "multi-beam operation" is used to refer to this aspect of the entire system. For illustrative purposes, this includes indicating the assigned DL or UL transmit (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 the DL or UL transmission via the selection of the corresponding receive (RX) beam.

[0090] Furthermore, the Antenna 500 system is also suitable for higher frequency bands, such as >52.6 GHz (also known as FR4). In this case, the system can only use analog beams. Due to O2 absorption loss near 60 GHz (an additional loss of approximately 10 dB at a distance of 100 meters), more and sharper analog beams (and therefore more radiators in the array) will be needed to compensate for the additional path loss.

[0091] An antenna port is defined such that the channel through which a symbol on the antenna port is transmitted can be inferred from the channel through which another symbol on the same antenna port is transmitted. Two antenna ports are said to be quasi-co-located (QCL) if the large-scale characteristics of the channel through which a symbol on one antenna port is transmitted can be inferred from the channel through which a symbol on another antenna port is transmitted. Large-scale characteristics include one or more of delay spread, Doppler spread, Doppler shift, average gain, average delay, and the spatial Rx parameter.

[0092] A UE can be configured with a list of up to M Transport Configuration Indicators (TCI)-States within the higher-layer parameter PDSCH-Config to receive PDSCH in the serving cell, where M depends on the UE capability maxNumberConfiguredTCIstatesPerCC. Each TCI-State contains parameters for configuring the QCL relationship between one or two downlink reference signals and the DMRS port of the PDSCH, the DMRS port of the corresponding PDCCH, or the CSI-RS port of the CSI-RS resource. The quasi-co-address relationship is configured by the higher-layer parameter qcl-Type1 for the first DL RS and qcl-Type2 (if configured) for the second DL RS. For the two DL RSs, the QCL types should not be the same, regardless of whether the reference is for the same DL RS or different DL RSs. The quasi-co-address type corresponding to each DL RS is given by the higher-layer parameter qcl-Type in QCL-Info and can take one of the following values:

[0093] - "QCL-TypeA": {Doppler frequency shift, Doppler spread, average delay, delay spread}

[0094] - "QCL-TypeB": {Doppler frequency shift, Doppler spread}

[0095] - "QCL-TypeC": {Doppler frequency shift, average delay}

[0096] - "QCL-TypeD": {Space Rx parameter}

[0097] The UE receives a MAC-CE activation command to map up to N (e.g., N=8) TCI states to code points in the DCI field "Transmission Configuration Indication". When transmitting HARQ-ACK information corresponding to the PDSCH carrying the MAC-CE activation command in time slot n, it should be after the MAC-CE application time (e.g., from time slot n). The first time slot that follows begins, in which It is a mapping between the TCI status indicated by the application and the code points of the DCI field "Transmission Configuration Indication" (the number of time slots per subframe used for the subcarrier spacing (SCS) configuration μ).

[0098] As operating bands in NR become higher, UEs are evolving to accommodate multiple antenna arrays 525 or panels (each capable of transmitting via an analog beam (e.g., analog BF 510)) to enhance various aspects of multi-beam operation, such as coverage enhancement, beam failure event minimization, and fast beam switching. By leveraging the capability of multiple panels, UE 116 can achieve a variety of diversity gains, resulting from the dynamic selection of panels with the best quality for the performance the system wants to optimize. For example, in 3GPP 5G NR Release 17, under the Unified Transport Configuration Indicator (TCI) framework, new features were identified and specified to facilitate UL beam / panel selection for UEs equipped with multiple panels, mitigating UL coverage loss from several aspects, such as the maximum permissible exposure (MPE) issue on UE 116.

[0099] For example, the beam corresponds to the spatial transmit / receive filter used by UE 116 and / or gNB 102. In one example, the beam may correspond to the spatial receive filter used by UE 116 to receive reference signals such as synchronization signals (SS) and physical broadcast channels (PBCH) (SS / PBCH blocks (SSB)) and / or CSI-RS, etc. In another example, the beam may correspond to the spatial transmit filter used by UE 116 to transmit reference signals such as UL probe reference signals (SRS), etc.

[0100] The beam training and measurement process may include, for example, a process in which gNB 102 configures a set of reference signal (RS) resources (such as SSB resources and / or CSI-RS resources) and a configuration for reporting settings to UE 116, enabling the UE to report beam quality metric measurements (such as Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), Received Signal Strength Indicator (RSSI), Signal-to-Noise Ratio (SNR), Signal-to-Interference-Noise Ratio (SINR), etc., each of which may be, for example, an L-1 measurement or a filtered L-3 measurement). In one example, UE 116 and / or gNB 102 may repeatedly transmit reference signals (RS), such as synchronization signal blocks (SSBs), CSI-RS, or SRS, using the same spatial transmission filter at multiple times, allowing gNB 102 and / or UE 116 to receive RS using different spatial reception filters respectively, to facilitate beam scanning and identification of candidate / optimal beams based on quality metrics (such as L1 / L3 RSRP or SINR). In one example, the selection and / or selection process for different spatial reception filters and / or quality metrics can be tailored to each UE / gNB implementation.

[0101] The beam indication procedure may include, for example, a procedure in which gNB 102 instructs UE 116 to transmit an uplink channel (and / or a second uplink signal) using the same spatial filter used to receive the (first) reference signal. In another example, gNB 102 may instruct UE 116 to receive a downlink channel (and / or a second downlink signal) using the same spatial filter used to receive the (first) reference signal. This indication may be, for example, DCI and / or MAC-CE and / or Radio Resource Control (RRC) signaling.

[0102] In one example, an antenna panel (or simply panel) may refer to an antenna array 525 or antenna subarray connected to one or more RF chains. In another example, a panel may be referred to as a transmit-receive entity (TRE), which may virtualize multiple physical panels into a single virtual panel based on a transparent UE / gNB implementation such as a MIMO diversity scheme.

[0103] The gNB 102 can utilize one or more transmit beams to cover an entire area of ​​a cell, such as coverage area 120. The gNB 102 can form transmit beams by applying appropriate gain and phase settings to the antenna array. Transmit gain, the power amplification of the transmitted signal provided by the transmit beam, is generally inversely proportional to the width or area covered by the beam. At lower carrier frequencies, better propagation loss makes it feasible for the gNB 102 to provide coverage using a single transmit beam; that is, sufficient received signal quality can be ensured at all UE locations within the coverage area by using a single transmit beam. In other words, at lower transmit signal carrier frequencies, the transmit power amplification provided by a transmit beam wide enough to cover the area may be sufficient to overcome propagation loss and ensure sufficient received signal quality at all UE locations within the coverage area. However, at higher signal carrier frequencies, the transmit beam power amplification corresponding to the same coverage area may be insufficient to overcome higher propagation loss, resulting in a degraded received signal quality at UE locations within the coverage area. To overcome this degradation in received signal quality, gNB 102 can form multiple transmit beams, each providing coverage over a narrower area than the entire coverage area; however, it provides sufficient transmit power amplification to overcome the higher signal propagation loss caused by using a higher transmit signal carrier frequency. UE 116 can also form a receive beam to increase the signal-to-interference-to-noise ratio (SINR) at the receiver. Similarly, in the uplink, UE 116 can form a transmit beam, and gNB 102 can form a receive beam.

[0104] To assist UE 116 in determining the RX and / or TX beams, a beam scanning procedure is performed. As part of the beam scanning procedure, gNB 102 transmits a set of transmit beams to scan the cell area, and UE 116 uses the UE 116 receive beams to measure the signal quality on different beams. To facilitate candidate beam identification, beam measurement, and beam quality reporting, gNB 102 configures one or more RS resources corresponding to the TX beam set to UE 116. RS resources can be SS blocks, periodic / aperiodic / semi-persistent CSI-RS resources, or CRI. An RS resource refers to a reference signal transmission over one or more combinations of time (OFDM symbol) / frequency (resource element) / spatial (antenna port) domain locations. For each RX beam, UE 116 reports the different TX beams received using that RX beam, arranged in order of signal strength (RSRP) (and optionally, CSI (CQI / PMI / RI)). Based on the UE 116 measurement report feedback, gNB 102 indicates the reception of PDCCH and / or PDSCH to UE 116 using one or more Transport Configuration Indicator (TCI) states.

[0105] A 5G terminal or UE can be equipped with multiple antenna elements. There can also be one or more antenna modules mounted on the terminal, each module having one or more antenna elements. Beamforming is a crucial factor when the UE 116 attempts to establish a connection with a BS (such as gNB 102). To compensate for the narrow analog beamwidth in millimeter wave (mmWave), analog beam scanning can be used to achieve wider signal reception or transmission coverage for the UE 116. The beamcodebook includes a set of codewords, where codewords are sets of analog phase shift values ​​or amplitude plus phase shift values ​​applied to antenna elements to form an analog beam. Millimeter wave beamcodebook design is critical and challenging for 5G millimeter wave base stations. Unlike low-frequency bands, millimeter wave antennas have inherent directivity, and millimeter wave signals are highly sensitive to obstructions and reflections.

[0106] Figure 6 An example antenna configuration on a mobile terminal according to an embodiment of the present disclosure is shown. Figure 6 The illustrated antenna configuration is for illustrative purposes only. Other embodiments may be used without departing from the scope of this disclosure. In some embodiments, UE 116 is a 5G terminal.

[0107] In some embodiments, UE 116 includes multiple antenna modules arranged on UE 116 to avoid coverage holes on the spherical surface and increase robustness against hand and body obstruction. Figure 6In the example shown, UE 116 includes a top antenna module 605, a right antenna module 610, and a left antenna module 615. Although three antenna modules 605, 610, and 615 are depicted, UE 116 may include more or fewer antenna modules without departing from the scope of this disclosure. In some embodiments, one or more of the antenna modules are located on the rear of UE 116.

[0108] Each antenna module can consist of a patch antenna, a dipole antenna array, or both. Figure 6 In the example shown, each antenna module 605, 610, and 615 is configured as a 1x4 patch uniform linear array. Larger arrays can improve beamforming gain, thereby increasing SNR and throughput. Power consumption also increases with the number of active antenna elements. For example, the power consumption of a single module 605 can be modeled as:

[0109] P tot =P base +γ DL N DL P ant,RX +γ UL N UL P ant,TX (1)

[0110] In equation 1, P tot It is the total power consumption, P base This is the basic power consumption of the activation module, P. ant,X (P ant, N is the daily antenna power consumption used for receiving (transmitting). DL (N UL ) is the number of active antenna elements used for downlink reception or uplink transmission, and γ DL ,γ UL (0≤γ DL +γ UL ≤1) is the duty cycle for downlink reception and uplink transmission.

[0111] Figure 7 An example fallback process for a terminal according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or intermediate steps. The process depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0112] In some examples, the UE is configured to perform LTE fallback whenever the UE overheats. For example, in operation 705, the UE may perform a temperature check. In operation 705, the UE measures the temperature from one or more antenna elements or transceivers. In operation 710, the UE determines whether the measured temperature exceeds a temperature control trigger. If the temperature does not exceed a temperature control threshold, in operation 715, the UE maintains full-chain beamforming operation, where all antenna elements in the antenna module chain remain active. If the temperature exceeds the temperature control threshold, in operation 720, the UE transitions to LTE fallback operation based on LTE.

[0113] LTE rollback is often undesirable due to the significant rollback costs. For example, maximum data rates may decrease from gigabits per second (Gbps) to hundreds of megabits per second (Mbps) or lower. Frequent switching of millimeter-wave antenna modules introduces additional latency and power consumption. In some embodiments, subchain operation can help control temperature and reduce the likelihood of LTE rollback.

[0114] In some embodiments, to reduce the power consumption of UE 116 and control the temperature of UE 116, UE 116 may choose to reduce the number of active antenna elements, i.e., N. DL (N UL A beam transmitted based on only a portion of the array is called a "subchain beam".

[0115] In this disclosure, the following notation is used: N ch (i) - The number of chains for the i-th antenna module; N UL (i) - The number of antenna chains transmitted for the uplink of the i-th antenna module; N DL (i) - the number of antenna chains for downlink reception of the i-th antenna module; T(i) - the temperature of the i-th antenna module; γ UL (i) - Duty cycle for uplink transmission of the i-th antenna module; γ DL (i) - the downlink reception duty cycle for the i-th antenna module; K(i) - the codebook size of the i-th antenna module; and G(θ,v) - the beam pattern on the unit sphere {(θ,φ)|0°≤θ≤180°,0°≤φ≤360°}.

[0116] Figure 8 and Figure 9 Examples of downlink-uplink correspondences with different numbers of chains according to embodiments of the present disclosure are shown. Figure 8 and Figure 9 The examples shown are for illustrative purposes only, and other embodiments may be used without departing from the scope of this disclosure.

[0117] exist Figure 8 The example shown depicts downlink transmission 800. UE 116 includes an antenna module 615 with seven antenna chains NB0-NB6. UE 116 can perform a beam scan operation to receive downlink transmission 800 from gNB 102. In the beam scan operation, UE 116 detects and receives downlink transmission 800 via a third antenna chain NB2.

[0118] exist Figure 9 The example shown depicts uplink transmission 900. After receiving downlink transmission, UE 116 uses all or a subset of its antenna elements to transmit uplink transmission 900. As a first example, UE 116 activates all antenna elements such that the number of chains used for DL ​​reception is equal to the number of chains used by UE 116 to maintain channel reciprocity. As another example, UE 116 may activate 3 antenna elements such that the number of chains used for downlink reception is greater than the number of chains used for uplink transmission 900. UE 116 may use sub-chain beamforming for transmission on UL to conserve uplink transmission power and control the temperature of UE 116. Since downlink transmission 800 is transmitted via a third antenna chain NB2, UE 116 activates antenna module 615 with seven antenna chains NB0-NB6. UE 116 may perform beam scanning to receive downlink transmission 800 from gNB102. In beam scanning operation, UE 116 detects and receives downlink transmission 800 via the third antenna chain NB2, which is the best receive beam among all antenna chains. Therefore, NB2 should be the best transmit beam, even among the three transmit chains (such as NB1-NB3). DL-UL beam correspondence is an important design standard because without DL-UL beam correspondence, an additional separate UL beam management process would be required.

[0119] In some embodiments, UE 116 is configured to select a subchain beamcodebook from a plurality of subchain beamcodebooks, the selection being based on at least one of the following: inter-chain beam correspondence requirements; temperature; power savings; signal strength / quality; maximum permissible exposure (MPE); or precoding matrix index (PMI) feedback.

[0120] Sub-chain beamcodebook design

[0121] Figures 10-12 Design metrics according to embodiments of this disclosure are shown. Figures 10-12 The embodiments of design metrics shown are for illustrative purposes only, and other embodiments may be used without departing from this disclosure.

[0122] UE 116 includes a sub-chain beamcodebook, which can be designed based on three different metrics for each different requirement and UE operation procedure. The three different metrics are: "Similarity Score" 1000, "Spherical Coverage (SC)" 1100, and "Beam Correspondence Spherical Coverage (BC-SC)" 1200.

[0123] In the first option of "Similarity Score" 1000, the sub-chain beam 1005 is designed to be similar to the full-chain beam 1010. That is, the radiation pattern of each sub-chain beam is designed to be similar to the radiation pattern of the corresponding full-chain beam (one-to-one mapping). The similarity between two beam patterns can be measured differently. In one approach, assuming uniform sampling points (θ, φ) on a unit sphere, the similarity score is defined according to the following formula:

[0124]

[0125] In equation 2, G i (θ,φ) is the radiation pattern of the i-th full-chain beam, and B(θ,φ) is the radiation pattern of the sub-chain beam. ∑ (θ,φ) The term is used to normalize the fractions such that 0 ≤ s i ≤1, and the similarity score between the beam and itself is 1.

[0126] In the second option, “Spherical Coverage” 1100, the sub-chain codebook is designed to maximize spherical coverage. There is no requirement for a one-to-one mapping between the sub-chain beam 1105 and the full-chain beam 1110, meaning that if the UE 116 switches from the full-chain codebook to the sub-chain codebook (or switches between two sub-chain codebooks), a new beam scan may be needed to determine the optimal beam. Different approaches exist for designing codebooks to maximize spherical coverage. Examples of different codebook design approaches include the greedy algorithm and the K-means algorithm given in Jianhua Mo, Boon Loong Ng, Sanghyun Chang, Pengda Huang, Mandar N. Kulkarni, Ahmad AlAmmouri, Jianzhong Charlie Zhang, Jeongheum Lee, and Won-Joon Choi, “Beam Codebook Design for 5G mmWave Terminals,” IEEE Access, July 2019 (incorporated hereby by reference).

[0127] In the third option of "Beam Corresponding Spherical Coverage" 1200, the sub-chain beam is designed to maximize the radiation pattern over the full-chain beam coverage area, which is a sub-region of the entire unit sphere. In this option, no new beam scan is required because the sub-chain beam is designed to cover an angular region similar to the full-chain beam. Therefore, for a given channel, if the corresponding full-chain beam is optimal, then this sub-chain beam is likely to be the optimal sub-chain beam. The process is as follows.

[0128] 1) Divide the unit sphere (0°≤θ≤180°, 0°≤φ≤360°) (or the angle coverage area required by the current module) into the coverage area of ​​the full-chain beam 1205. For example, if there are K beams, we get D1∪D2∪…D K-1 ∪D K ={(θ,φ)|0°≤θ≤180°,0°≤φ≤360°}, where D k It is the angular region covered by the full-chain beam k.

[0129] 2) For each angular region covered by the full-chain beam 1205, find the optimal sub-chain beam 1210.

[0130] In some embodiments, the codebook design exhaustively searches all possible chain combinations. For example, when designing a 3-chain beamformer for a 1x5 array, there are... There are several possible combinations. For each combination, the beamforming weights are optimized. For example, if the first, second, and fourth chains are activated, the beamforming weights w = [w1, w2, 0, w4, 0] are optimized to maximize the design metric. When the array size is not too large, the complexity of exhaustive search is acceptable.

[0131] Table 1 provides an example codebook for the 5-element module case. For a full-chain beam, all 5 antennas are activated, while for a 3-chain beam, only 3 of the 5 elements are activated, resulting in non-zero beamforming weights. Similarly, for a 2-chain beam, only two antennas are activated. In this table, inter-chain beam correspondence is assumed. For example, if the first full-chain beam [1j-1–j 1] is now used and the UE decides to switch to 3-chain operation to save power, the UE can directly apply the first 3 sub-beams [j-1–j 0 0] without a new beam scan.

[0132] Table 1: Sub-chain beamcodebook for a 1x5 array with 2-bit phase shifters. Note that for each row, inter-chain beam correspondence is assumed.

[0133]

[0134]

[0135] Choose from three different design metrics.

[0136] Figure 13 An example process for codebook selection based on inter-chain beam correspondence according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or intermediate steps. The process depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0137] In some embodiments, UE 116 may have at least two sub-chain codebooks, which can be designed or generated offline. UE 116 can select one of them in real time based on operational requirements. In some embodiments, the selection of the sub-chain codebook depends on the requirement for inter-chain beamforming. In operation 1305, it is determined whether inter-chain beamforming is required. In operation 1310, if inter-chain beamforming is not required, a codebook that does not have the characteristic of inter-chain beamforming (e.g., based on the previously described "spherical coverage" metric) can be selected. In some examples, UE 116 operates using a certain number of chains and wants to change the number of chains for reasons such as temperature control, power saving, etc. If UE 116 performs a new beam scan after changing the number of chains to determine the optimal sub-chain beam, UE 116 can determine that the codebook based on the "spherical coverage" metric is likely the most suitable codebook. Otherwise, in operation 1315, if inter-link beam correspondence is required, UE 116 can select another codebook with inter-link beam correspondence characteristics, that is, it can be a codebook designed / generated for "similarity score" or BC-SC metric.

[0138] Figure 14 An example process for codebook selection based on inter-chain beam correspondence and beam measurement according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or middle steps. The process depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0139] In operation 1405, it is determined whether inter-chain beam correspondence is required. If inter-chain beam correspondence is not required, then in operation 1410, UE 116 selects a codebook based on the "spherical coverage" metric. Otherwise, two other codebooks can be selected. First, in operation 1415, it is determined whether the UE beam measurement using the previous number of chains is outdated. If, in operation 1415, it is determined that the UE beam measurement using the previous codebook is not outdated, stale, or unreliable, then in operation 1420, the UE selects a codebook based on the "beam correspondence spherical coverage" metric. That is, if UE 116 performs a beam scan before changing the number of chains, UE 116 can roughly estimate the angle of arrival (AoA) as the angle within the coverage area of ​​the current optimal beam, and should select the beam that maximizes beamforming gain in that angle area. Therefore, the codebook based on the metric BC-SC is the most suitable codebook. Note that the BC-SC design process actually assumes that a beam scan is performed before implicitly changing the number of chains. Finally, if in operation 1415 it is determined that the UE beam measurement using the previous codebook is outdated / unreliable or may have become outdated / unreliable, then UE 116 selects a codebook based on a "similarity score" metric. That is, because the UE does not scan the beam before or after changing the number of chains, or because of recent UE rotation, or hand obstruction during a beam scan cycle, the selected measurement-based optimal beam may not be the actual optimal beam. The UE can select a "similarity score" metric in operation 1425, which maintains the similarity between the previous and new beams as much as possible. Note that the beam is not guaranteed to be optimal because there is no beam scan before or after changing the number of chains. To determine if a beam measurement is outdated, the UE can set a timer that is reset after each measurement and indicates that the measurement is outdated when the countdown reaches zero. Sensors on the phone can detect rotation and nearby obstructions, and if rapid rotation occurs during the measurement cycle or hand obstruction is detected, the measurement can be declared unreliable.

[0140] Figure 15 An example process for codebook selection based on terminal beam scanning timing according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without intermediate or middle steps. The process 1500 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0141] In some embodiments, the subchain beamcodebook selection is determined by the UE beam scan timing relative to the change in the number of chains. In operation 1505, if the UE 116 performs a new beam scan after changing the number of chains to determine the optimal subchain beam, then in operation 1510, the codebook based on the "spherical coverage" metric is selected as the most suitable codebook. Otherwise, in operation 1515, if the UE 116 performs a beam scan before changing the number of chains, then in operation 1520, the codebook based on the BC-SC metric is selected as the codebook. Otherwise, if the UE 116 does not perform a scan according to operation 1505 or 1515, then in operation 1525, the codebook based on the "similarity score" metric is selected.

[0142] Beam correspondence evaluation for subchain beam operations

[0143] Current requirements in 3GPP only consider the full-chain scenario and do not apply to sub-chain scenarios. Therefore, in some embodiments, the scheme "beam correspondence tolerance" is borrowed from 3GPP (TR38.101-2, part 6.6.4.2) to evaluate the beam correspondence of the sub-chain codebook. This scheme compares the gap between two EIRPs in the angular region above the median where pure UE beam scanning results. This scheme currently only applies to the case where "beamCorrespondenceWithoutUL-BeamSweeping" is not present, which means that a separate UL beam management process exists.

[0144] The evaluation process for the proposed solution is as follows.

[0145] 1) EIRP1: The total EIRP in dBm, calculated based on the beam autonomously selected by the UE using DL beam scanning (referred to as "beam-corresponding spherical coverage" in this paper).

[0146] 2) EIRP2: Optimal total EIRP (i.e., "spherical coverage") dependent on UL beam scanning

[0147] 3) Check the angular region corresponding to the first 50% percentage of EIRP2 (i.e., only half a spherical region). Depending on the design criteria, other percentage points may also be selected.

[0148] 4) Calculate ΔEIRP BC =EIRP2-EIRP1

[0149] 5) Check the ΔEIRP for a certain percentage (e.g., 85%, 90%, 95%, or other percentages, depending on design requirements). BCIf it is less than a certain threshold (e.g., 1dB, 3dB, or other values ​​depending on design requirements), then the requirement is met.

[0150] Sub-chain beam operation

[0151] Basic UE Procedures for Determining DL / UL Beam Operation Schemes

[0152] In some embodiments, UE 116 may choose to use the same number of chains or not use the same number of chains during reception and transmission. UL =N DL The scheme restricts the UE's operational choices; however, it maintains beam correspondence, thereby maintaining channel reciprocity. UL ≠N DL The solution is more flexible for UEs to adjust the link based on power usage, temperature, battery level, channel strength / quality, etc.

[0153] In some embodiments, UE 116 uses a sub-chain for transmission and a full-chain for reception, i.e., N UL ≤N DL =N ch Because transmitting consumes more power than receiving, UE 116 can save more power and efficiently reduce temperature by using a sub-chain for transmitting instead of receiving. Alternatively, full-chain Rx operation facilitates downlink reception at UE 116.

[0154] PMI Feedback

[0155] Figure 16 An example process for scheme selection based on precoded matrix index PMI feedback according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or parts thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without intermediate or middle steps. The process 1600 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0156] In operation 1605, UE 116 checks the configuration of the PMI (Precoding Matrix Index) feedback to determine the subchain operation scheme. If UE 116 is not configured with PMI feedback, then in operation 1610, gNB 102 measures the uplink channel itself and determines the downlink precoding by assuming channel reciprocity. In this case, UE 116 should apply the same number of chains (i.e., N) for both DL and UL. UL =N DL ) or a similar number of chains (i.e., |N) UL -N DL|<∈), making the DU and UL beams the same or sufficiently similar. If UE 116 is configured with PMI feedback, in operation 1615, UE 116 measures the downlink channel, determines the PMI, and feeds the PMI back to gNB 102. Therefore, beam correspondence between the Tx and Rx beams of UE 116 is not required, and UE 116 can flexibly set the chain, for example, N UL ≠N DL or |N UL -N DL |≥∈。 For 3GPP 5G NR, if UE 116 is configured with CSI-ReportConfig, where the higher-layer parameter reportQuantity is set to “cri-RI-PMI-CQI” or “cri-RI-LI-PMI-CQI”, then UE 116 is considered to be configured with PMI feedback; otherwise, UE is not configured with PMI feedback.

[0157] Temperature control

[0158] Figure 17 An example process for temperature-dependent sub-chain / full-chain operation according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or intermediate steps. The process 1700 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0159] In operation 1705, UE 116 checks the temperature to determine whether a subchain should be applied. UE 116 may check the temperature periodically. In operation 1710, UE 116 determines whether temperature control has been triggered. If temperature control is triggered, UE 116 employs subchain beaming in operation 1715. Otherwise, UE 116 employs full-chain beaming in operation 1720.

[0160] Figure 18 An example process for temperature-based sub-chain operation according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or intermediate steps. The process 1800 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0161] In some embodiments, UE 116 is configured to reduce the number of chains as temperature increases. For example, for an antenna model with 4 chains, UE 116 may rely on a temperature list sorted in ascending order, T1<T2<T3<T4. In Figure 18 the illustrated example, in operation 1805, UE 116 checks the temperature to determine whether a sub-chain should be applied. UE 116 may check the temperature periodically. In operation 1810, UE 116 determines whether temperature control has been triggered. If the temperature control is triggered, then in operation 1815, UE 116 employs Y-chain beams. Otherwise, in operation 1820, UE 116 maintains X-chain operation. In process 1800, Y is less than X. After each of operations 1815 and 1820, UE 116 checks the temperature again in operation 1805, and determines in operation 1810 whether temperature control has been triggered. If no trigger occurs, the UE maintains the currently transmitted chain beam; but if a trigger occurs, UE 116 reduces the lower sub-beam chain. For example, when the temperature is below T1, UE 116 sets N UL =N DL =4; when the temperature is between T1 and T2, UE 116 sets N UL =N DL =3; when the temperature is between T2 and T3, UE 116 sets N UL =N DL =2; when the temperature is between T3 and T4, the UE sets N UL =N DL =1; and if the temperature is above T4, UE 116 turns off the entire antenna module. UE 116 may attempt other antenna modules that are not as overheated as the current antenna module, or choose to fall back to a sub-6GHz LTE or sub-6GHz 5G connection or other connection technologies that help mitigate overheating.

[0162] In some embodiments, as the temperature changes, UE 116 may not use the same number of chains for DL and UL. In a first option, UE 116 first reduces N UL to a minimum, and then reduces N DL , because transmission typically consumes more power than reception. For example, if there are five chains, UE 116 may set [N DL ,N UL =

[55] →

[54] →

[53] →

[52] →

[51] →

[41] →

[31] →

[21] →

[11] as the temperature increases. In a second option, UE 116 iteratively reduces N UL and N DL . For example, [N DL ,N UL]=

[55] →

[54] →

[44] →

[43] →

[33] →

[33] →

[23] →

[21] →

[11] . In this case, N DL Or equal to N UL Or more than N UL A value of 1 ensures a high probability of beamforming being maintained. In the third option, UE116 reduces the number of chains based on power consumption. UE116 first sorts [N] chains in descending order of power consumption. DL N UL Sort the lists and then deactivate the downlink / uplink chains in that order. Note that if there is a minimum number of chains required to maintain a connection with the BS, the ordered list above can be modified accordingly. For example, in the first option, if 3-chain beamforming is required to maintain a connection with the gNB102, the modified list could be [N...]. DL N UL ] =

[55] →

[54] →

[53] →

[43] →

[33] .

[0163] Signal strength / quality

[0164] In some embodiments, UE 116 determines the number of chains based on signal strength / quality. If the signal strength / quality is above a threshold or sufficient to support the required data rate, UE 116 may activate a smaller number of chains. Signal strength / quality can be determined based on RSRP / RSRQ / SNR / SINR, etc. If the signal strength / quality drops below a threshold or is insufficient to support the required data rate, UE 116 activates more and more chains until the signal strength / quality is above the threshold or meets the data rate requirements.

[0165] Battery Level

[0166] In some embodiments, UE 116 determines the number of chains based on battery level. If the battery level is below a threshold (e.g., 20%), UE 116 may activate a smaller number of chains, particularly those used for uplink transmission, to extend battery life.

[0167] Maximum Permissible Exposure

[0168] Maximum Permissible Exposure (MPE) is the maximum level at which a person may be exposed to electromagnetic radiation without harm to the eyes or skin. In some embodiments, if full-chain beam transmission exceeds the maximum permissible limit, UE 116 may use sub-chain beam transmission. The number of chains can be determined based on the radiated power of the antenna module, the distance to the operator's eyes or skin on UE 116, and MPE requirements determined by a regulatory body such as the FCC. The higher the transmission power and the closer the eyes or skin are to the antenna module, the fewer chains should be used for transmission.

[0169] Upper management requirements

[0170] In some embodiments, UE 116 determines the number of chains based on upper-layer requirements. If the upper layer has strict requirements on data rate or latency, for example, if UE 116 is streaming or displaying live video, a full-chain beamforming can be used. If there are no strict constraints on data rate or latency, for example, if UE 116 is in idle mode or simply browsing the internet, a smaller number of chains can be activated.

[0171] Take into account temperature control, PMI feedback, signal strength, battery level, MPE and other factors.

[0172] Figure 19 An example process for subchain operations based on various factors according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, the sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without any intermediate or middle steps. The process 1900 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0173] In some embodiments, UE 116 determines the number of UL and DL chains by jointly considering multiple factors. In operation 1905, UE 116 first checks one or more of the following: temperature, signal strength, battery level, or MPE. For example, UE 116 checks one or more of the following: high temperature; high signal strength, such as compared to data rate requirements; low battery level; or if radiation does not meet MPE requirements. If none of these conditions are met, then in operation 1910, UE 116 can apply full-chain DL and UL operation, i.e., N DL =N UL =N chAlternatively, if either condition is met, in operation 1915, UE 116 further checks whether PMI feedback is configured. If UE 116 does not receive PMI feedback configuration, meaning that gNB 102 precoding requires channel reciprocity, then in operation 1920, UE 116 applies the same number of subchains for DL ​​and UL, i.e., N. DL =N UL <N ch Alternatively, if PMI feedback is configured, UE 116 can apply different numbers of chains for DL ​​and UL in operation 1925. In procedure 1900, UE 116 applies fewer chains for UL than for DL ​​to save transmit power.

[0174] Duty cycle reduction process

[0175] Figure 20 An example process for reducing the antenna duty cycle for an Rx beam according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, a sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without intermediate or intermediate steps. The process 2000 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0176] In some embodiments, UE 116 applies sub-chain beams for beam measurement and full-chain beams for data reception. In procedure 2000, UE 116 performs a UE antenna duty cycle reduction procedure, where UE 116 saves power and reduces heat when performing beam measurement with sub-chain beams, but maximizes signal quality when receiving data with full-chain beams. If uplink beam measurement is present, UE 116 may also perform a similar procedure for the Tx beam.

[0177] In Operation 2005, the UE determines whether the RX beam is used for beam measurement rather than data reception. If the RX beam is not used for beam measurement, then in Operation 2010, the UE 116 can apply full-chain DL operation, i.e., N. DL =N ch If, in Operation 1920, UE 116 determines that the RX beam is used for beam measurement, then in Operation 2015, UE 116 applies a smaller number of subchains to the DL, i.e., N. DL <N ch .

[0178] Figure 21An example process for reducing the antenna duty cycle according to this disclosure is shown. Although the flowchart depicts a series of sequential steps, unless explicitly stated otherwise, one should not infer from this sequence a specific order of execution, a sequential execution of steps or portions thereof rather than simultaneous or overlapping execution, or the execution of steps specifically depicted without intermediate or intermediate steps. The process 2100 depicted in the illustrated example is implemented by, for example, a transmitter chain in a mobile station.

[0179] In some embodiments, UE 116 determines when to apply the antenna duty cycle reduction procedure based on temperature. In operation 2105, UE 116 checks the temperature to determine whether a sub-chain should be applied. UE 116 may check the temperature periodically. If temperature control is triggered in operation 2110, then in operation 2115, UE 116 applies the antenna duty cycle reduction procedure. Alternatively, in operation 2120, UE 116 applies a normal procedure, where the same number of chains are used for measurement and data reception.

[0180] Beam scanning during chain change

[0181] When the number of chains changes, UE 116 can choose to 1) perform a full beam scan to determine the optimal new beam, or 2) perform a partial scan searching only nearby beams, or 3) choose not to search and directly apply the corresponding beam, assuming a perfect one-to-one mapping. In some embodiments, if the number of chains changes slightly, UE 116 performs a partial search or does not scan the beam at all. For example, if the previous beam (N) DL N UL ) and new beam (N′ DL ,N′ UL The chain sizes of ) are close, i.e., |N DL -N′ DL |<δ(or|N) UL -N′ UL If |<δ), then UE 116 can assume that the inter-chain beam mapping is quite good, thus ignoring the full scan operation. Otherwise, UE 116 scans the entire beamcodebook to determine the optimal new beam.

[0182] Beam management parameter adjustment for sub-chain beamcodebook

[0183] In some embodiments, beam management parameters can be adjusted when UE 116 applies subchain operation. UE 116 typically sets an RSRP threshold to trigger specific actions in beam management. For example, if the RSRP of the current antenna module drops below the threshold, other antenna modules are scanned to find a better module. If UE 116 applies subchain operation instead of full-chain operation, the RSRP threshold should be adjusted. For example, the RSRP threshold used to trigger module scanning in full-chain / subchain operation can be represented as RSRP.th (N ch ) and RSRP th (N DL ), UE 116 sets RSRP th (1) <RSRP th (2) <… <RSRP th (N ch The threshold gap can be determined based on the CDF curve of the spherical cover. For example, if the CDF curve of the full-chain codebook is 10 dB better than the CDF curve of the 1-chain codebook at 50% (or 100%, 20%, or average), then the UE can set the RSRP. th (1) = RSRP th (N ch -10dB.

[0184] Sub-chain control per module

[0185] The above subchain beam operation is not limited to the case of a single module UE, but can be applied to UEs with multiple modules.

[0186] In some embodiments, sub-chain beamforming operations for multiple antenna modules are performed separately. Multiple temperature sensors may be mounted on the UE 116, with each sensor positioned close to one antenna module. Therefore, different numbers of chains can be used if the modules have different temperatures. Furthermore, the signal strength of a module may vary depending on the antenna type (e.g., patch or dipole), orientation, hand obstruction, wireless channel, etc. Therefore, the number of chains used to achieve the same SNR / throughput can differ between modules, and the UE 116 can apply separate sub-chain operations.

[0187] The beam measurement table updates when the number of chains changes.

[0188] In some embodiments of beam measurement (BM) operation, UE 116 may maintain a beam measurement table. In some embodiments, when the number of chains changes, UE 116 first maps its beam measurement table from the previous number of chains to the new number. This mapping of the measurement table, while potentially imperfect, can still be performed and is better than a cold start measurement of the new sub-chain beams. This measurement provides UE 116 with an approximate measurement table, which UE 116 can use to operate when attempting a flash out to a new table.

[0189] If the codebook is designed using a "similarity score" metric, mapping can be performed by scaling the old measurement table with the similarity score. If represented as G... i The previous beam measurement (θ,φ) is V. GWatts or milliwatts (scaled linearly, not in dB) are represented as B. i The beam measurement of the new beam corresponding to (θ,φ) (on a linear scale, not a dB scale) can be set to... Where s i The similarity score is defined according to the following formula:

[0190]

[0191] In other words, B i (θ,φ)=s i G i (θ,φ)+Δ(θ,φ), where Δ(θ,φ) is the same as G i (θ,φ) orthogonal residual beam pattern difference, i.e., ∑ (θ,φ) G i (θ,φ)Δ(θ,φ)=0. Therefore, if the channel gain is expressed as γ(θ,φ), then the beam measurement of the new beam is:

[0192] ∑ (θ,φ) γ(θ,φ)B i (θ,φ)=∑ (θ,φ) γ(θ,φ)(s i G i (θ,φ)+Δ(θ,φ))=s i ∑ (θ,φ) γ(θ,φ)G i (θ,φ)+∑ (θ,φ) γ(θ,φ)Δ(θ,φ) (4)

[0193] Because channel gain and residual beam pattern difference are independent, the expectation of their inner product is zero. Therefore, The expectation for channel realization is equal to

[0194] If the codebook is designed using the metric of "spherical coverage beam correspondence," then mapping can also be performed by scaling the old measurement table. If represented as G... i The previous beam measurements of (θ,φ) are Watts or milliwatts are represented as B. i The beam measurement of the corresponding new beam at (θ,φ) can be set to... Where s′ i It is represented as D i The similarity score over the coverage area of ​​the previous beam is defined by the following formula:

[0195]

[0196] If the codebook is designed using the metric of "spherical coverage" or typically in the absence of inter-chain beam correspondence, the mapping can be performed as follows: First, find the closest beam B to the current beam from the previous codebook. i The beam is (θ,φ). This can be done by evaluating the similarity score as described above. The radiation pattern of the selected beam is represented as G. j (θ,φ). Second, use G j (θ,φ) and B i Scaling G using the similarity score between (θ, φ) j Beam measurement of (θ,φ). Another method is to first measure the beam pattern B. i (θ,φ) are projected onto the previous codebook G. k (θ,φ), 1≤k≤K. If the projection is B... i (θ,φ)=α1G1(θ,φ)+α2G2(θ,φ)+…+α K G K Given (θ,φ)+Δ(θ,φ), the measurement of the new beam can be set as follows:

[0197] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications will be apparent to those skilled in the art. This disclosure is intended to include such changes and modifications that fall within the scope of the appended claims. Nothing described herein should 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.

Claims

1. A user equipment (UE) in a wireless communication system, the UE comprising: The transceiver is configured to communicate with the base station (BS) via a wireless communication medium; as well as A processor, coupled to the transceiver, is configured to: Beam scanning is used to identify the entire chain of beams used for downlink reception; Determine the number of active chains to be used for uplink transmission; as well as When inter-chain beam correspondence exists, the uplink transmission beam of the sub-chain is determined based on partial beam scanning including the corresponding sub-chain beam and the nearby sub-chain beam. The inter-chain beam correspondence includes a one-to-one beam mapping between the sub-chain beam and the full-chain beam.

2. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on the UE's temperature by reducing the number of active chains used for uplink transmission when the UE's temperature is above a threshold.

3. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on the uplink throughput requirement by reducing the number of active chains used for uplink transmission when the uplink throughput requirement is low.

4. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on the PMI feedback requirements from the BS, when the UE is not configured with precoding matrix indicator (PMI) feedback, by using the same chains for both uplink and downlink.

5. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on the MPE by reducing the number of active chains used for uplink transmission when the radiation exposure is close to the maximum permissible exposure MPE.

6. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on the battery level by reducing the number of active chains used for uplink transmission when the battery level is below a threshold.

7. The UE according to claim 1, wherein, The processor is also configured to determine the number of active chains for uplink transmission based on a joint consideration of temperature control, uplink throughput requirements, precoding matrix indicator (PMI) feedback requirements, battery level, and maximum permissible exposure (MPE).

8. The UE according to claim 1, wherein, The processor is configured to determine the uplink transmission beam of the sub-chain based on the downlink beam of the entire chain when an inter-chain beam correspondence exists, without scanning the sub-chain beam. The inter-chain beam correspondence includes a one-to-one beam mapping between the sub-chain beam and the entire chain beam.

9. The UE according to claim 1, wherein, The processor is configured to design subchain beams based on different metrics, including one or more of the following: similarity, spherical coverage, or beam-to-spherical coverage. The processor is configured to determine the subchain uplink transmission beam without performing beam scanning if one or more subchain beams are designed based on one or more metrics including similarity or beam-corresponding spherical coverage.

10. A method performed by a user equipment (UE) in a wireless communication system, the method comprising: Beam scanning is used to identify the full-chain beams for downlink reception from the base station (BS). Determine the number of active chains to be used for uplink transmission; as well as When inter-chain beam correspondence exists, the uplink transmission beam of the sub-chain is determined based on partial beam scanning including the corresponding sub-chain beam and the nearby sub-chain beam. The inter-chain beam correspondence includes a one-to-one beam mapping between the sub-chain beam and the full-chain beam.

11. The method according to claim 10, wherein, Determining the number of active chains for uplink transmission includes: reducing the number of active chains for uplink transmission when the UE's temperature is above a threshold, based on the UE's temperature.

12. The method according to claim 10, wherein, Determining the number of active chains for uplink transmission includes: when uplink throughput requirements are low, the number of active chains for uplink transmission is reduced, and the number of active chains for uplink transmission is determined based on the uplink throughput requirements.

13. The method according to claim 10, wherein, Determining the number of active chains for uplink transmission includes: using the same chains for both uplink and downlink when the UE is not configured with precoding matrix indicator (PMI) feedback, and determining the number of active chains for uplink transmission based on the PMI feedback requirements from the BS.

14. The method of claim 10, wherein, Determining the number of active chains for uplink transmission includes: determining the number of active chains for uplink transmission based on the MPE by reducing the number of active chains for uplink transmission when radiation exposure is close to the maximum permissible exposure (MPE).

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