WO2022257116A1 - Suppression d'une source d'intermodulation passive externe - Google Patents

Suppression d'une source d'intermodulation passive externe Download PDF

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Publication number
WO2022257116A1
WO2022257116A1 PCT/CN2021/099741 CN2021099741W WO2022257116A1 WO 2022257116 A1 WO2022257116 A1 WO 2022257116A1 CN 2021099741 W CN2021099741 W CN 2021099741W WO 2022257116 A1 WO2022257116 A1 WO 2022257116A1
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Prior art keywords
antenna array
epim
source
transceiving antenna
wireless communication
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PCT/CN2021/099741
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English (en)
Inventor
Andrei Malkov
Zhi Yang
Qiang Huo
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Huawei Technologies Co., Ltd.
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Priority to PCT/CN2021/099741 priority Critical patent/WO2022257116A1/fr
Publication of WO2022257116A1 publication Critical patent/WO2022257116A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting

Definitions

  • the present disclosure relates generally to the field of wireless communications, and particularly to techniques that allow to suppress an external passive intermodulation (EPIM) source in a near field of a transceiving antenna array included in a wireless communication apparatus (e.g., a user equipment (UE) or a Radio Access Network (RAN) node) .
  • a wireless communication apparatus e.g., a user equipment (UE) or a Radio Access Network (RAN) node.
  • UE user equipment
  • RAN Radio Access Network
  • An EPIM source differs from an internal PIM (IPIM) source in that the EPIM source is excited by electromagnetic waves emitted by a transceiving antenna array of a wireless communication apparatus and spreading through a space around the transceiving antenna array. The electromagnetic waves are then reflected by the EPIM source and reach, through the space as well, the transceiving antenna array. Thus, the EPIM source is located in a near field of the transceiving antenna array. In turn, the IPIM source is located inside the transceiving antenna array.
  • IPIM internal PIM
  • a wireless communication apparatus comprises a transceiving antenna array, a data storage comprising processor-executable instructions, and at least one processor coupled to the data storage and the transceiving antenna array. Being executed by the at least one processor, the processor-executable instructions cause the at least one processor to operate as follows. At first, the at least one processor causes the transceiving antenna array to transmit a wireless communication signal over an outbound wireless channel. Then, the at least one processor monitors whether the transceiving antenna array receives a distorted version of the wireless communication signal over an inbound wireless channel.
  • the at least one processor determines that (i) the wireless communication signal has been reflected by at least one EPIM source in a near field of the transceiving antenna array, and (ii) the outbound wireless channel comprises an outbound wireless subchannel between the at least one EPIM source and the transceiving antenna array.
  • the at least one processor calculates a signal matrix for the inbound wireless channel based on the distorted version of the wireless communication signal, and determines a number of the at least one EPIM source in the near field of the transceiving antenna array based on the signal matrix.
  • the at least one processor uses the number of the at least one EPIM source to obtain a set of candidate precoders for suppressing the at least one EPIM source, and calculate a channel matrix for the outbound wireless subchannel based on the set of candidate precoders.
  • the at least one processor obtains a final precoder for suppressing the at least one EPIM source based on the channel matrix.
  • the final precoder may be then applied to the transceiving antenna array to suppress the EPIM source (s) .
  • the wireless communication apparatus performs the estimation of the channel matrix without considering the electromagnetic model of the transceiving antenna array and the EPIM source (s) .
  • the transceiving antenna array comprises N antenna elements and the number of the at least one EPIM source is equal to K.
  • the at least one processor is configured to obtain the set of candidate precoders as follows. At first, the at least one processor generates a set of L precoders by using an optimization algorithm, where L ⁇ N-K.
  • the optimization algorithm comprises an objective function, and the objective function provides L rates each associated with one of the set of L precoders.
  • the at least one processor selects N-K candidate precoders from the set of L precoders based on the L rates. By so doing, it is possible to obtain the set of candidate precoders more efficiently.
  • the at least one processor is further configured to select the objective function based on the signal matrix for the inbound wireless channel.
  • the objective function thus selected allows one to select the most suitable candidate precoders for further processing (which is aimed at finding the final precoder) .
  • the at least one processor is configured to determine the signal matrix for the inbound wireless channel by applying an autocorrelation function to the distorted version of the wireless communication signal. In this way, the signal matrix for the inbound wireless channel may be determined efficiently and accurately.
  • the at least one processor is further configured to present a space around the transceiving antenna array as a set of virtual spaced nodes.
  • the at least one processor is configured to obtain the set of candidate precoders based on the number of the at least one EPIM source and the set of virtual spaced nodes. By so doing, it is possible to obtain the set of candidate precoders in which each candidate precoder is focused to a certain virtual spaced node from the set of virtual spaced nodes. In other words, each candidate precoder is obtained such that it maximizes a voltage induced in an antenna dipole, provided that the antenna dipole is positioned in the certain virtual spaced node.
  • the set of virtual spaced nodes is arranged in a vicinity of the at least one EPIM source in the near field of the antenna array.
  • the at least one processor is configured to obtain the final precoder based on the channel matrix for the outbound wireless subchannel in view of a precoder for a far field of the transceiving antenna array. By so doing, it is possible to obtain the most efficient final precoder.
  • a method for operating a wireless communication apparatus comprises a transceiving antenna array.
  • the method starts with the step of transmitting, by the transceiving antenna array, a wireless communication signal over an outbound wireless channel. Then, the method proceeds to the step of monitoring whether the transceiving antenna array receives a distorted version of the wireless communication signal over an inbound wireless channel.
  • the method further goes on to the step of determining that (i) the wireless communication signal has been reflected by at least one EPIM source in a near field of the transceiving antenna array, and (ii) the outbound wireless channel comprises an outbound wireless subchannel between the at least one EPIM source and the transceiving antenna array.
  • the method proceeds to the steps of calculating a signal matrix for the inbound wireless channel based on the distorted version of the wireless communication signal, and determining a number of the at least one EPIM source in the near field of the transceiving antenna array based on the signal matrix.
  • the method proceeds to the steps of obtaining a set of candidate precoders for suppressing the at least one EPIM source based on the number of the at least one EPIM source, and calculating a channel matrix for the outbound wireless subchannel based on the set of candidate precoders.
  • the method subsequently goes on to the step of obtaining a final precoder for suppressing the at least one EPIM source based on the channel matrix.
  • the final precoder may be applied to the transceiving antenna array to suppress the EPIM source (s) . By so doing, it is possible to efficiently find and suppress the EPIM source (s) in the near field of the transceiving antenna array.
  • the method according to the second aspect allows one to estimate the channel matrix without considering the electromagnetic model of the transceiving antenna array and the EPIM source (s) . This is an important advantage because such an electromagnetic model may yield inaccurate estimates of the channel matrix, thereby leading to high losses in DL beamforming.
  • the transceiving antenna array comprises N antenna elements and the number of the at least one EPIM source is equal to K.
  • the set of candidate precoders is obtained as follows. At first, a set of L precoders is generated by using an optimization algorithm, where L ⁇ N-K.
  • the optimization algorithm comprises an objective function which provides L rates each associated with one of the set of L precoders. After that, N-K candidate precoders are selected from the set of L precoders based on the L rates. By so doing, it is possible to obtain the set of candidate precoders more efficiently.
  • the objective function is selected based on the signal matrix for the inbound wireless channel.
  • the objective function thus selected allows one to select the most suitable candidate precoders for further processing (which is aimed at finding the final precoder) .
  • the signal matrix for the inbound wireless channel is determined by applying an autocorrelation function to the distorted version of the wireless communication signal. In this way, the signal matrix for the inbound wireless channel may be determined efficiently and accurately.
  • the method further comprises the step of presenting a space around the transceiving antenna array as a set of virtual spaced nodes.
  • the set of candidate precoders is obtained based on the number of the at least one EPIM source and the set of virtual spaced nodes.
  • the set of virtual spaced nodes is arranged in a vicinity of the at least one EPIM source in the near field of the antenna array.
  • the final precoder is obtained based on the channel matrix for the outbound wireless subchannel in view of a precoder for a far field of the transceiving antenna array.
  • a computer program product comprises a computer-readable storage medium storing a computer code which, when executed by at least one processor, causes the at least one processor to perform the method according to the second aspect.
  • FIG. 1 schematically explains how external passive intermodulation (EPIM) affects wireless communications between a transceiving antenna array and a target wireless communication apparatus;
  • EPIM external passive intermodulation
  • FIG. 2 shows a block diagram of a wireless communication apparatus in accordance with one exemplary embodiment
  • FIG. 3 shows a flowchart of a method for operating the wireless communication apparatus shown in FIG. 2 in accordance with one exemplary embodiment.
  • a wireless communication apparatus may refer to an apparatus configured to participate in wireless communications in a wireless communication network (e.g., a cellular or mobile network) .
  • the wireless communication apparatus comprises a transceiving antenna array configured to receive and transmit wireless communication signals over inbound and outbound wireless channels.
  • the wireless communication apparatus may be implemented as a user equipment (UE) or a Radio Access Network (RAN) node.
  • UE user equipment
  • RAN Radio Access Network
  • the UE may refer to a mobile device, a mobile station, a terminal, a subscriber unit, a mobile phone, a cellular phone, a smart phone, a cordless phone, a personal digital assistant (PDA) , a wireless communication device, a desktop computer, a laptop computer, a tablet computer, a single-board computer (SBC) (e.g., a Raspberry Pi device) , a gaming device, a netbook, a smartbook, an ultrabook, a medical device or medical equipment, a biometric sensor, a wearable device (e.g., a smart watch, smart glasses, a smart wrist band, etc. ) , an entertainment device (e.g., an audio player, a video player, etc.
  • SBC single-board computer
  • the UE may refer to at least two collocated and inter-connected UEs thus defined.
  • a vehicular component or sensor e.g., a driver-assistance system
  • a smart meter/sensor e.g., an unmanned vehicle (e.g., an industrial robot, a quadcopter, etc. ) and its component (e.g., a self-driving car computer)
  • industrial manufacturing equipment e.g., a global positioning system (GPS) device, an Internet-of-Things (IoT) device, an Industrial IoT (IIoT) device, a machine-type communication (MTC) device, a group of Massive IoT (MIoT) or Massive MTC (mMTC) devices/sensors, or any other suitable device configured to support wireless communications.
  • the UE may refer to at least two collocated and inter-connected UEs thus defined.
  • the RAN node may refer to a fixed point of communication for the UE in a particular wireless communication network. More specifically, the RAN node may be used to connect the UE to a Data Network (DN) through a Core Network (CN) and may be referred to as a base transceiver station (BTS) in terms of the 2G communication technology, a NodeB in terms of the 3G communication technology, an evolved NodeB (eNodeB) in terms of the 4G communication technology, and a gNB in terms of the 5G New Radio (NR) communication technology.
  • the RAN node may serve different cells, such as a macrocell, a microcell, a picocell, a femtocell, and/or other types of cells.
  • the macrocell may cover a relatively large geographic area (for example, at least several kilometers in radius) .
  • the microcell may cover a geographic area less than two kilometers in radius, for example.
  • the picocell may cover a relatively small geographic area, such, for example, as offices, shopping malls, train stations, stock exchanges, etc.
  • the femtocell may cover an even smaller geographic area (for example, a home) .
  • the RAN node serving the macrocell may be referred to as a macro node
  • the RAN node serving the microcell may be referred to as a micro node, and so on.
  • an inbound wireless channel may be considered as an UL channel if the matter concerns wireless communications from a lower-level wireless communication apparatus to a higher-level wireless communication apparatus (e.g., from a UE to a BTS, or the like) .
  • An outbound wireless channel may be considered as a DL channel if the matter concerns wireless communications from a higher-level wireless communication apparatus to a lower-level wireless communication apparatus (e.g., from a BTS to a UE, or the like) .
  • the present disclosure is not limited to the usage of the DL and UL channels, and there may be embodiments in which the inbound and outbound wireless channels are used to establish wireless communications between wireless communication apparatuses at the same level (e.g. between two UEs, or between two RAN nodes) , for which reason the inbound and outbound wireless channels may be considered as sidelink channels.
  • the wireless communication apparatus may adjust the wireless channels by using precoders.
  • a precoder may refer to a vector or a matrix for processing wireless signals and may be also referred to as a precoding matrix, beamformer, or beamforming matrix.
  • the precoder may refer to a processor, a module, or a functional block that processes a wireless signal using such a vector or matrix, and, correspondingly, may be referred to as a beamforming unit/module, precoding unit/module, or the like.
  • Wireless communications performed, for example, by a BTS with a UE may be adversely affected by one or more EPIM sources present in a near field of the transceiving antenna array of the BTS.
  • an EPIM source may refer to an object that may generate PIM outside the transceiving antenna array in response to electromagnetic waves emitted by the transceiving antenna array to perform the wireless communications.
  • Examples of such an EPIM source include one or more rusty bolts and/or other corrosive elements in the near field of the transceiving antenna array.
  • the near field may refer to a region in which there are strong inductive and capacitive effects from currents and charges in the transceiving antenna array that cause electromagnetic components that do not behave like a far-field radiation.
  • FIG. 1 schematically explains how EPIM affects wireless communications between a transceiving antenna array 100 and a target wireless communication apparatus 102.
  • the target wireless communication apparatus 102 is shown as a smartphone.
  • the transceiving antenna array 100 it may belong to another UE (e.g., another smartphone) or a RAN node (e.g., a BTS) .
  • the transceiving antenna array comprises multiple antenna elements which are schematically shown as crosses in FIG. 1.
  • the transceiving antenna array 100 transmits a wireless signal to the smartphone 102 over an outbound wireless channel 104 and receives a wireless response signal from the smartphone 102 over an inbound wireless channel 106.
  • the transceiving antenna array 100 operates in a frequency-division duplexing (FDD) mode (i.e.
  • FDD frequency-division duplexing
  • some part of the wireless signal propagating from the transceiving antenna array 100 towards the smartphone 102 over the outbound wireless channel 104 may be distorted and reflected by the EPIM source 108 back to the transceiving antenna array 100 over the near-field inbound wireless subchannel 112, thereby partially interfering with the wireless response signal propagating from the smartphone 102 towards the transceiving antenna array 100 over the inbound wireless channel 106.
  • the transceiving antenna array 100 belongs to a RAN node (e.g., a BTS) , and there is more than one EPIM source 108.
  • the outbound wireless channel 104 is an DL channel
  • the inbound wireless channel 106 is a UL channel
  • the outbound wireless subchannel 110 is a near-field DL (NF-DL) subchannel
  • the inbound wireless subchannel 112 is a NF-UL subchannel.
  • the NF-DL subchannel 110 is represented by a channel matrix H (f) which is defined as follows:
  • f is the carrier frequency
  • N is the number of the antenna elements
  • K is the number of the EPIM sources 108
  • h l is the NF-DL subchannel from the l-th antenna element to the m-th EPIM source 108.
  • the DL channel 104 comprises two component carriers, with one using a carrier frequency f 1 and another using a carrier frequency f 2 .
  • the UL channel 106 operates at a carrier frequency f UL .
  • a current which is induced in the k-th EPIM-source 108 is as follows:
  • I EPIM (k, t) c k U (k, t) U (k, t) U* (k, t) ,
  • U (k, t) is the voltage induced in the k-th EPIM source 108 at the time instant t
  • c k is the unknown factor characterizing the k-th EPIM source 108
  • H is the Hermitian operator
  • a part of the wireless signal, which is reflected (with some distortion) from the k-th EPIM-source 108 and received by the transceiving antenna array 100, is represented by a vector S k (t) as follows:
  • H UL is the channel matrix representing the UL channel 106:
  • a signal S (t) which denotes all parts of the wireless signal that are reflected from all K EPIM-sources 108 and received by the transceiving antenna array 100, is defined as follows:
  • the part of S (t) denoted by which falls within an UL frequency band used by the UL channel 106, interferes with the wireless response signal transmitted by the smartphone 102.
  • IPIM suppression methods To suppress caused by the EPIM source (s) 108, one may use classical IPIM suppression methods. However, although the classical IPIM suppression methods are also applicable for EPIM suppression, these methods are impractical for antenna arrays with a large number of antenna elements N (e.g., in case of using a massive MIMO technology) because of their polynomial O (N 4 ) complexity.
  • the precoder W (f) may be designed by using a suboptimal approach and an optimal approach.
  • the precoder W (f) is designed without considering the estimation of the NF-DL subchannel 110.
  • the suboptimal approach allows for a high rate of the EPIM suppression, but a gain loss caused by this precoder in DL beamforming is also high.
  • the NF-DL subchannel 110 is estimated (i.e. the channel matrix H (f) is determined) , whereupon the precoder W (f) is calculated using this estimate as follows:
  • W opt (f) w (f) -H (f) H (f) H w (f) ,
  • W opt (f) w (f) -H s (f) w (f) .
  • W opt (f) and w (f) should as small as possible to provide the EPIM suppression and, at the same time, to avoid the high gain loss caused by using the precoder W opt (f) .
  • the prior art does not disclose any methods for estimating the channel matrix of the NF-DL subchannel 110 (i.e. a subchannel established between the transceiving antenna array 100 and the EPIM source (s) 108) .
  • the prior art merely discloses methods for estimating the channel matrix of the DL channel 104 (i.e. a channel established between the transceiving antenna array 100 and the smartphone 102) .
  • the channel matrix of the DL channel 104 is typically estimated by using the classical formulation of the problem, in which the far field is implied.
  • the channel matrix of the NF-DL subchannel 110 may be also estimated by using the electromagnetic model of the transceiving antenna array 100 and the EPIM source (s) 108.
  • creating such an accurate electromagnetic model is a very laborious task, which should be accomplished for every antenna array modification.
  • the electromagnetic model is created inaccurately, this can lead to an inaccurate estimate of the channel matrix, and consequently, high losses in DL beamforming.
  • It is also possible to select one of available candidate precoders as the final precoder, i.e. W opt (f) but such a selection depends very much on the accuracy of the electromagnetic model (which, as noted above, is difficult or even impossible to achieve) .
  • the exemplary embodiments disclosed herein provide a technical solution that allows mitigating or even eliminating the above-sounded drawbacks of the prior art.
  • the technical solution disclosed herein involves suppressing one or more EPIM sources (like the EPIM source 108) in the near field of a transceiving antenna array by estimating a channel matrix (i.e. H (f) or H s (f) ) of a NF-DL subchannel (like the NF-DL subchannel 110) between the transceiving antenna array and the EPIM source (s) , without considering the electromagnetic model of the transceiving antenna array and the EPIM source (s) .
  • a channel matrix i.e. H (f) or H s (f)
  • the estimation of the channel matrix is based on the results of measurements taken on the transceiving antenna array of each individual wireless communication apparatus, for which reason this estimation takes into account all particularities of each individual case of antenna array design, placement and installation conditions.
  • W opt (f) a DL precoder
  • FIG. 2 shows a block diagram of a wireless communication apparatus 200 in accordance with one exemplary embodiment.
  • the apparatus 200 may be implemented as a UE (like the smartphone 102 in FIG. 1) or a RAN node.
  • the apparatus 200 comprises a processor 202, a data storage 204, and a transceiving antenna array 206.
  • the data storage 204 stores processor-executable instructions 208.
  • the processor-executable instructions 208 cause the processor 202 to transmit a wireless communication signal 210 over an outbound wireless channel 212, monitor whether a distorted version 214 of the wireless communication signal 210 is received by the transceiving antenna array 206 over an inbound wireless channel 216, and, if the distorted version 214 is received, obtain a final precoder, as will be described further in more detail.
  • the number, arrangement and interconnection of the constructive elements constituting the apparatus 200 which are shown in FIG. 2, are not intended to be any limitation of the present disclosure, but merely used to provide a general idea of how the constructive elements may be implemented within the apparatus 200.
  • the processor 202 may be replaced with several processors, as well as the data storage 204 may be replaced with several removable and/or fixed storage devices, depending on particular applications.
  • the transceiving antenna array 206 may be implemented as two individual antenna arrays, with one for a receiving operation and another for a transmitting operation. It is also assumed that the processor 202 may perform different operations required to process received data and prepare transmission data, such, for example, as signal modulation/demodulation, encoding/decoding, etc.
  • the processor 202 may be implemented as a CPU, general-purpose processor, single-purpose processor, GPU, microcontroller, microprocessor, application specific integrated circuit (ASIC) , field programmable gate array (FPGA) , digital signal processor (DSP) , complex programmable logic device, etc. It should be also noted that the processor 202 may be implemented as any combination of one or more of the aforesaid. As an example, the processor 202 may be a combination of two or more microprocessors.
  • the data storage 204 may be implemented as a classical nonvolatile or volatile memory used in the modern electronic computing machines.
  • the nonvolatile memory may include Read-Only Memory (ROM) , ferroelectric Random-Access Memory (RAM) , Programmable ROM (PROM) , Electrically Erasable PROM (EEPROM) , solid state drive (SSD) , flash memory, magnetic disk storage (such as hard drives and magnetic tapes) , optical disc storage (such as CD, DVD and Blu-ray discs) , etc.
  • ROM Read-Only Memory
  • RAM Ferroelectric Random-Access Memory
  • PROM Programmable ROM
  • EEPROM Electrically Erasable PROM
  • SSD solid state drive
  • flash memory examples thereof include Dynamic RAM, Synchronous DRAM (SDRAM) , Double Data Rate SDRAM (DDR SDRAM) , Static RAM, etc.
  • the processor-executable instructions 208 stored in the data storage 204 may be configured as a computer-executable code which causes the processor 202 to perform the aspects of the present disclosure.
  • the computer-executable code for carrying out operations or steps for the aspects of the present disclosure may be written in any combination of one or more programming languages, such as Java, C++, or the like.
  • the computer-executable code may be in the form of a high-level language or in a pre-compiled form and be generated by an interpreter (also pre-stored in the data storage 204) on the fly.
  • FIG. 3 shows a flowchart of a method 300 for operating the wireless communication apparatus 200 in accordance with one exemplary embodiment. Each step of the method 300 is intended to be performed by the corresponding constructive element (s) of the apparatus 200.
  • the method 300 starts with a step S302, in which the processor 202 causes the transceiving antenna array 206 to transmit the wireless communication signal 210 over the outbound wireless channel 212.
  • the wireless communication signal 210 may be configured as a test signal that is not intended for any target wireless communication apparatus, but is merely used to “scan” the near field of the transceiving antenna array 206 for any EPIM source (s) .
  • the method 300 proceeds to a step S304, in which the processor 202 monitors whether the transceiving antenna array 206 receives the distorted version 214 of the wireless communication signal 210 over the inbound wireless channel 216.
  • the steps S302 and S304 may be performed in the so-called communications (or radio) silence mode, i.e.
  • the method 300 further goes on to a step S306, in which the processor 202 determines that (i) the wireless communication signal 210 has been reflected by at least one EPIM source in the near field of the transceiving antenna array 206, and (ii) the outbound wireless channel 212 comprises an outbound wireless subchannel (like the NF-DL subchannel 110 in FIG.
  • the method 300 proceeds to a step S308, in which the processor 202 calculates a signal matrix for the inbound wireless channel 216 based on the distorted version 214 of the wireless communication signal 210.
  • the signal matrix is used, in a next step S310, by the processor 202 to determine a number of the EPIM source (s) in the near field of the transceiving antenna array 206.
  • the method 300 proceeds to a step S312, in which the processor 202 obtains a set of candidate precoders for suppressing the EPIM source (s) based on the number of the EPIM source (s) .
  • the set of candidate precoders is used, in a next step S314, by the processor 202 to calculate a channel matrix (i.e. H (f) or H s (f) ) for the outbound wireless subchannel.
  • a channel matrix i.e. H (f) or H s (f)
  • the signal matrix characterizes a received signal (e.g., in this case, the distorted version 214 of the wireless communication signal 210)
  • the channel matrix characterizes a wireless communication channel (e.g., in this case, the outbound wireless subchannel) .
  • the channel matrix is equivalent to a voltage induced in the EPIM source (s) , and this voltage may depend on the polarization, coordinates (relatively to the transceiving antenna array 206) and other properties of the EPIM source (s) .
  • the method 300 subsequently goes on to a step S316, in which the processor 202 obtains the final or DL precoder (i.e. W opt (f) ) for suppressing the EPIM source (s) based on the channel matrix.
  • the final precoder may be then applied to the transceiving antenna array 206 to suppress the influence of the EPIM source (s) .
  • the processor 202 may perform the step S312, i.e. obtain the set of candidate precoders, as follows. At first, the processor 202 generates a set of L precoders by using an optimization algorithm, where L ⁇ N-K. There is a variety of optimization algorithms known in the art, each of which is aimed at finding a set of inputs to an objective function that results in a maximum or minimum function evaluation. The selection of a certain optimization algorithm for generating the set of L precoders depends on particular application.
  • the objective function of the optimization algorithm may provide L rates each associated with one of the set of L precoders.
  • the objective function may be selected, for example, based on the signal matrix for the inbound wireless channel 216, which is obtained in the step S308 of the method 300.
  • the processor 202 may select N-K candidate precoders from the set of L precoders based on the L rates. By so doing, it is possible to obtain the most suitable set of candidate precoders.
  • the processor 202 may determine, in the step S308 of the method 300, the signal matrix for the inbound wireless channel 216 by applying an autocorrelation function to the distorted version 214 of the wireless communication signal 210. In this way, the signal matrix for the inbound wireless channel 216 may be determined efficiently and accurately.
  • the method 300 may comprise an additional step, in which the processor 202 presents a space around the transceiving antenna array 206 as a set of virtual spaced nodes.
  • This additional step may be performed either before the first step S302 of the method 300 (e.g., once the transceiving antenna array 206 is installed in a certain position) , or before the step S312 of the method 300 (e.g., in parallel with or after any of the steps S302-310) .
  • the set of virtual spaced nodes may be arranged either randomly, or in a vicinity of the supposed EPIM source (s) in the near field of the transceiving antenna array 206.
  • the processor 202 may obtain, in the step S312 of the method 300, the set of candidate precoders based on the number of the EPIM source (s) and the set of virtual spaced nodes.
  • the set of candidate precoders in which each candidate precoder is focused to a certain virtual spaced node from the set of virtual spaced nodes.
  • each candidate precoder is obtained such that it maximizes a voltage induced in an antenna dipole, provided that the antenna dipole is positioned in the certain virtual spaced node.
  • the processor 202 may obtain, in the step S316 of the method 300, the final precoder based on the channel matrix for the outbound wireless subchannel in view of a precoder for a far field of the transceiving antenna array 206. By so doing, it is possible to obtain the most efficient final precoder.
  • Step S310
  • the number of the EPIM sources K may be detected, for example, from an auto-correlation matrix where is the UL signal defined as a part of S (t) (the equation for S (t) is given above when discussing FIG. 1) , and H is the Hermitian operator. K may be estimated as a number of non-zero eigenvectors of this matrix.
  • the auto-correlation may be conveniently used in the step S310 because the signal matrix obtained in the step S308 is usually not a square matrix, and the autocorrelation allows the signal matrix to be converted to some square matrix from which it is possible to calculate the eigenvectors and, correspondingly, K.
  • Step S312 (combined with the above-mentioned additional step) :
  • the processor 202 may generate the set of L ⁇ N-K precoders (hereinafter referred to as the NF precoders for short) , where K is the number of EPIM sources, and N is the number of antenna elements in the transceiving antenna array 206.
  • Each NF precoder W suppresses K EPIM sources.
  • the matrix W is composed of the generated NF precoders:
  • the precoder W l is to compose it from two terms: the far-field (FF) precoder w and a set of NF precoders represented by a matrix V, namely:
  • the FF precoder w is a column-vector of length N
  • V is the matrix of size N by
  • a is the column-vector of linear combination coefficients of length is the number of the NF precoders. is the estimate of the number of the EPIM sources (which is obtained in the step S306 of the method 300) .
  • the FF precoder w may be generated using a discrete Fourier transform (DFT) matrix as follows:
  • w may be generated, for example, using two columns (rows) of the DFT matrix and combining them by means of the Kronecker product.
  • the columns of the matrix V are the NF precoders.
  • the number of the columns of the matrix V is equal to the estimated number of the EPIM sources, i.e.
  • Each NF precoder may be, for example, selected from a precomputed set of NF precoders.
  • each NF precoder may be focused to specific one of the virtual spaced nodes.
  • the NF precoder denoted as v which is focused to coordinates [x y z] , may be expressed as:
  • v n is the weight of the antenna element n
  • k 0 is the wave number
  • k 0 is the wave number
  • the column-vector a may be found analytically. However, to do this, it would be necessary to know the vectors of an electromagnetic field at the point of the coordinates which the NF precoder is focused to, and, possibly, the spatial directivity of the EPIM sources.
  • the former could be derived from the electromagnetic model of the transceiving antenna array 206, if available. The later should be estimated.
  • column-vector a may be found by using the optimization algorithm, which solves the problem:min a f (a) ,
  • f (a) is the objective function of the optimization algorithm, which may be represented, for example, by a sum of powers of UL signals received by all antenna elements in the transceiving antenna array 206.
  • the reason to generate more than N-K NF precoders and then to select N-K best NF precoders is that the optimization algorithm, which searches for the optimal column-vector a, may fail for some of the NF precoders.
  • the best N-K NF precoders may be selected, for example, based on the rates provided by the objective function f (a) . If the column-vector a obtained by applying the optimization algorithm to the NF precoder W k is denoted by a (k) , then those NF precoders are selected, for which the objective function f (a (k) ) is the smallest.
  • the matrix composed of the selected NF precoders is denoted by
  • Step S314
  • the processor 202 calculates a kernel of the matrix
  • the processor 202 calculates the channel matrix H S as follows:
  • Step S316
  • the processor 202 may find the final precoder based on the channel matrix H S and the FF precoder w as follows:
  • W opt (f) w (f) -H s (f) w (f) .
  • the final precoder thus obtained enables the most efficient suppression of the EPIM source (s) in the near field of the transceiving antenna array 206.
  • each step or operation of the method 300 can be implemented by various means, such as hardware, firmware, and/or software.
  • one or more of the steps or operations described above can be embodied by processor executable instructions, data structures, program modules, and other suitable data representations.
  • the executable instructions which embody the steps or operations described above can be stored on a corresponding data carrier and executed by the processor 202.
  • This data carrier can be implemented as any computer-readable storage medium configured to be readable by the processor 202 to execute the processor executable instructions.
  • Such computer-readable storage media can include both volatile and nonvolatile media, removable and non-removable media.
  • the computer-readable media comprise media implemented in any method or technology suitable for storing information.
  • the practical examples of the computer-readable media include, but are not limited to information-delivery media, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile discs (DVD) , holographic media or other optical disc storage, magnetic tape, magnetic cassettes, magnetic disk storage, and other magnetic storage devices.

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  • Computer Networks & Wireless Communication (AREA)
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Abstract

La présente divulgation porte sur des techniques qui permettent de supprimer une source d'intermodulation passive externe (EPIM) dans un champ proche d'un réseau d'antennes d'émission-réception inclus dans un appareil de communication sans fil. Pour ce faire, une matrice de canal d'un sous-canal sans fil sortant entre le réseau d'antennes d'émission-réception et la ou les sources EPIM est estimée, sans tenir compte d'un modèle électromagnétique du réseau d'antennes d'émission-réception et de la ou des sources EPIM. Au lieu de cela, l'estimation de la matrice de canal est basée sur les résultats de mesures prises sur le réseau d'antennes d'émission-réception, pour cette raison, cette estimation tient compte de toutes les particularités de chaque cas individuel de conception de réseau d'antennes, de conditions de placement et d'installation. Ainsi, on peut obtenir une estimation précise de la matrice de canal qui peut être ensuite utilisée pour calculer un précodeur de liaison descendante qui supprime efficacement la ou les sources EPIM et ne provoque pas de pertes élevées dans la formation de faisceau de liaison descendante.
PCT/CN2021/099741 2021-06-11 2021-06-11 Suppression d'une source d'intermodulation passive externe WO2022257116A1 (fr)

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EP4318995A4 (fr) * 2021-05-21 2024-08-21 Huawei Tech Co Ltd Procédé et appareil de traitement de communication

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US20130310090A1 (en) * 2012-05-21 2013-11-21 Aceaxis Limited Method and Apparatus for Reduction of Intermodulation Products
WO2016099593A1 (fr) * 2014-12-18 2016-06-23 Commscope Technologies Llc Système et procédé de localisation de source d'intermodulation passive
US20190007078A1 (en) * 2017-06-30 2019-01-03 At&T Intellectual Property I, L.P. Facilitation of passive intermodulation cancelation via machine learning
US20200145264A1 (en) * 2018-11-01 2020-05-07 Viavi Solutions Inc. Passive intermodulation (pim) measurements in common public radio interface (cpri) spectrum analysis
CN112205056A (zh) * 2018-05-16 2021-01-08 瑞典爱立信有限公司 具有波束控制和无源互调感知的上行链路-下行链路协同调度

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US20130310090A1 (en) * 2012-05-21 2013-11-21 Aceaxis Limited Method and Apparatus for Reduction of Intermodulation Products
WO2016099593A1 (fr) * 2014-12-18 2016-06-23 Commscope Technologies Llc Système et procédé de localisation de source d'intermodulation passive
US20190007078A1 (en) * 2017-06-30 2019-01-03 At&T Intellectual Property I, L.P. Facilitation of passive intermodulation cancelation via machine learning
CN112205056A (zh) * 2018-05-16 2021-01-08 瑞典爱立信有限公司 具有波束控制和无源互调感知的上行链路-下行链路协同调度
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EP4318995A4 (fr) * 2021-05-21 2024-08-21 Huawei Tech Co Ltd Procédé et appareil de traitement de communication

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