WO2014153732A1 - Procédé et appareil d'estimation de canaux et d'égalisation pour communication ultrasonique - Google Patents

Procédé et appareil d'estimation de canaux et d'égalisation pour communication ultrasonique Download PDF

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Publication number
WO2014153732A1
WO2014153732A1 PCT/CN2013/073256 CN2013073256W WO2014153732A1 WO 2014153732 A1 WO2014153732 A1 WO 2014153732A1 CN 2013073256 W CN2013073256 W CN 2013073256W WO 2014153732 A1 WO2014153732 A1 WO 2014153732A1
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WO
WIPO (PCT)
Prior art keywords
channel
channel response
linear equalizer
change
threshold
Prior art date
Application number
PCT/CN2013/073256
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English (en)
Chinese (zh)
Inventor
孟剑强
刘明刚
张江红
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北京印声科技有限公司
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Publication date
Application filed by 北京印声科技有限公司 filed Critical 北京印声科技有限公司
Priority to CN201380073758.1A priority Critical patent/CN105052101A/zh
Priority to PCT/CN2013/073256 priority patent/WO2014153732A1/fr
Publication of WO2014153732A1 publication Critical patent/WO2014153732A1/fr
Priority to HK15112094.3A priority patent/HK1211396A1/xx

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/005—Control of transmission; Equalising
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception

Definitions

  • the present invention relates to channel estimation and equalization techniques, and in particular to a channel estimation and equalization method and apparatus for ultrasonic communication.
  • Channel estimation and equalization techniques have been extensively studied in wireless communication, and proposed, for example, channel estimation techniques based on least mean square (LMS), channel estimation techniques based on least squares (LS), and recursive least squares (RLS).
  • LMS least mean square
  • LS least squares
  • RLS recursive least squares
  • MMS least mean square
  • LS least squares
  • RLS recursive least squares
  • MSE maximum likelihood sequence detection
  • MAP maximum a posteriori probability
  • the channel estimation and equalization techniques used in wireless communications are highly complex and computationally intensive.
  • the present invention has been made in view of the above technical problems, and an object thereof is to provide a channel estimation and equalization method and apparatus for ultrasonic communication, which can reduce multipath effect and inter-code crosstalk of an ultrasonic signal during transmission, and is remarkable Reduce the amount of calculations and track changes in the channel.
  • a channel estimation and equalization method for ultrasonic communication comprising: estimating a channel response in response to receiving an ultrasonic signal; and using the linear equalizer to the ultrasonic signal based on the estimated channel response Performing equalization; and according to the channel
  • the coefficient of the linear equalizer is adjusted by the change in response.
  • a channel estimation and equalization apparatus for ultrasonic communication, comprising: a channel estimator configured to estimate a channel response in response to receiving an ultrasonic signal; a linear equalizer configured And equalizing the ultrasonic signal based on the estimated channel response; and an adjuster configured to adjust a coefficient of the linear equalizer according to the change in the channel response.
  • FIG. 1 is a schematic flow chart of a channel estimation and equalization method for ultrasonic communication according to an embodiment of the present invention
  • Figure 2 is a schematic flow chart showing an example of adjusting coefficients of a linear equalizer in the method of the embodiment shown in Figure 1;
  • Figure 3 is a schematic flow chart showing another example of adjusting the coefficients of the linear equalizer in the method of the embodiment shown in Figure 1;
  • FIG. 4 is a schematic block diagram of a channel estimation and equalization apparatus for ultrasonic communication, in accordance with one embodiment of the present invention. detailed description
  • FIG. 1 shows a schematic flow chart of a channel estimation and equalization method for ultrasonic communication in accordance with one embodiment of the present invention.
  • the present embodiment will be described in detail below with reference to the accompanying drawings.
  • the channel response of the ultrasonic channel is estimated in response to receiving the ultrasonic signal.
  • the ultrasonic signal may use a frequency in the range of 20 kHz to 22 kHz, and may take the form of a frame.
  • Each frame of the ultrasonic signal may include a header and a data portion.
  • the header uses a pseudo-random code (PN) sequence, for example, a PN code sequence of code length 31 is used.
  • PN pseudo-random code
  • the ultrasonic signal is frequency modulated for transmission.
  • the frequencies used for frequency modulation can be 20.5 kHz and 21.5 kHz, respectively.
  • the processing including channel compensation, extracting frequency domain signals, signal filtering and normalization, synchronization processing, etc., obtains a synchronized frequency domain signal of the ultrasonic signal.
  • Channel estimation is performed on the ultrasonic channel based on the obtained synchronized frequency domain signal.
  • the initial channel response of the ultrasonic channel can be calculated using the synchronous frequency domain signal of the ultrasonic signal (hereinafter referred to as "ultrasonic signal" for convenience of explanation).
  • the initial channel response can be calculated using an existing channel estimation method.
  • C-1, r n represents a sequence of PN codes with a value of ⁇ -1, 1 ⁇ , and y n represents the received ultrasound at time n
  • FFT Fast Fourier Transform
  • EW represents the mean.
  • a minimum mean square (LMS) based adaptive estimation is performed on the calculated initial channel response to obtain a channel response of the ultrasonic channel.
  • the initial channel response h is estimated in the time domain using the PN code sequence in the header of each frame of the ultrasonic signal, and the channel at the beginning of the data portion of the frame is obtained. response.
  • the step size can be set to 0.005.
  • the ultrasonic signal is equalized using a linear equalizer based on the estimated channel response in step S120.
  • the linear equalizer can adaptively equalize the signal based on the minimum mean square error (MMSE).
  • MMSE minimum mean square error
  • the coefficient vector of the linear equalizer needs to be calculated at each sampling instant, and the channel response of the ultrasonic channel changes with time, in order to reduce the amount of calculation, the coefficient vector of the linear equalizer can be adjusted according to the change of the channel response.
  • the adjustment method of the coefficient of the linear equalizer will be specifically described below with reference to Figs. 2 and 3.
  • Fig. 2 shows a schematic flow chart showing an example of the adjustment of the coefficients of the linear equalizer.
  • step S210 the line is calculated according to the channel response at the current sampling time.
  • the current sampling instant is set to the start time n 1 of the data portion of the frame of the ultrasonic signal (> such that, by the above-described step S110, the channel response of the current sampling instant is obtained / ⁇ .
  • the adaptive equalization method can obtain the coefficient vector c of the linear equalizer at the current sampling moment.
  • step S220 the channel response of the current sampling moment and the amount of change of the channel response at the subsequent sampling moment are calculated.
  • the amount of change can reflect the change of the channel.
  • the subsequent sampling instant is the next moment ( m+i ) of the current sampling instant.
  • the channel at time (I +1 ) can be obtained by the above step siio Response /
  • the absolute value of the change in channel response can be made in the amount of change in channel response.
  • the comparison is in step S220 calculates the amount of change and the predetermined channel change threshold.
  • step S240 the coefficient of the linear equalizer at the subsequent sampling instant is calculated using the adaptive equalization method of the signal described above, and the channel response of the subsequent sampling instant is set to the channel response of the current sampling instant. In the above example, at this point, the current sampling time becomes
  • step S230 If the comparison result of step S230 indicates that the amount of change is smaller than the channel change threshold, then in step S250, The coefficient of the linear equalizer at the current sampling instant. In the above example, the coefficient vector of the linear equalizer remains unchanged. Then, for the next sampling instant (+2) of the current sampling instant (+1), repeat the above change.
  • the quantity calculation step S220 and the comparison step S230 are performed until one frame of the ultrasonic signal ends.
  • Fig. 3 shows a schematic 3 ⁇ 4 ⁇ 2 diagram illustrating another example of the adjustment of the coefficients of the linear equalizer.
  • steps S310 to S340 are the same as steps S210 to S240 in Fig. 2, except for the processing when the amount of change is smaller than the channel change threshold.
  • the coefficient of the linear equalizer at the current sampling instant is updated using a minimum mean square (LMS) based adaptive estimate in step S350 to track subtle changes in the channel.
  • LMS minimum mean square
  • the step size is set to 0.005.
  • step S360 determining, according to the updated coefficient of the linear equalizer, The first threshold of the number ⁇ . Due to the inherent specificity of the linear equalizer, when there are more coefficients close to zero in its coefficient vector, it will bring more noise to the output. Therefore, some coefficients need to be forced to zero.
  • the first threshold may be determined based on the relative magnitude of the coefficients of the linear equalizer.
  • the first threshold may be determined to be 0.1 of the absolute value of the maximum of the updated coefficients of the linear equalizer. It will be readily apparent to one of ordinary skill in the art that the first threshold can also be defined in other ways.
  • the updated respective coefficients of the linear equalizer are compared with the first threshold.
  • the absolute value of each coefficient can be compared to a first threshold.
  • the updated coefficient of, for example, the linear equalizer whose absolute value is smaller than the first threshold is set to zero.
  • the step size of the LMS estimation used in updating the coefficients of the linear equalizer may be adjusted according to the ratio of the number of zeroing coefficients to the number of all coefficients. When the zeroing coefficient is larger, the step size is adjusted larger.
  • the method of the present embodiment can adaptively perform channel estimation and equalization, reduce multipath effects and inter-code crosstalk caused by transmission of ultrasonic signals in space, and can adjust linear equalizer according to channel changes.
  • the coefficients are such that the channel changes are quickly tracked so that channel estimation and equalization can accommodate channel variations.
  • the method of this embodiment has the advantage of a small amount of calculation.
  • Fig. 4 shows a schematic block diagram of a channel estimation and equalization apparatus 400 for ultrasonic communication in accordance with one embodiment of the present invention.
  • the present embodiment will be described in detail below with reference to the accompanying drawings, wherein the description of the same portions as those of the previous embodiment will be appropriately omitted.
  • the channel estimation and equalization apparatus 400 of the present embodiment includes: a channel estimator 401 configured to estimate a channel response of an ultrasonic channel in response to receiving an ultrasonic signal; a linear equalizer 402 configured to be based on The estimated channel response, equalizing the ultrasonic signal; and an adjuster 403 configured to adjust the coefficients of the linear equalizer 402 based on changes in the channel response.
  • the received ultrasonic signal is subjected to appropriate processing to obtain a synchronized frequency domain signal of the ultrasonic signal, and is supplied to the apparatus 400 of the present embodiment.
  • the channel estimator 401 pairs the ultrasonic wave according to the synchronous frequency domain signal of the ultrasonic signal (hereinafter referred to as "ultrasonic signal":)
  • the channel performs channel estimation to obtain the channel response of the ultrasonic channel.
  • channel response calculation module 4011 in channel estimator 401 calculates the initial channel response of the ultrasound channel using the ultrasound signal. As previously discussed, channel response calculation module 4011 can estimate the channel response using existing channel estimation methods.
  • the adaptive estimation module 4012 performs a least mean square based adaptive estimation on the obtained initial channel response to obtain a channel response of the ultrasonic channel.
  • linear equalizer 402 The channel response is then provided to a linear equalizer 402 to equalize the ultrasonic signals.
  • the coefficients of linear equalizer 402 can be adjusted by regulator 403 based on changes in channel response.
  • linear equalizer 402 can equalize the ultrasonic signals using existing adaptive equalization methods.
  • the coefficient calculation module 4031 calculates the coefficient of the linear equalizer 402 at the current sampling instant based on the channel response of the current sampling instant obtained by the channel estimator 401.
  • the delta calculation module 4032 can then calculate the amount of change in the channel response at the current sampling instant and the channel response at the subsequent sampling instant.
  • the channel response at the subsequent sampling instant is obtained by the channel estimator 401.
  • the amount of change in the channel response is defined as the absolute value of the difference between the channel response at the current sampling instant and the channel response at the subsequent sampling instant.
  • the first comparison module 4033 then compares the calculated amount of change to a predetermined channel change threshold.
  • the coefficient calculation module 4031 calculates the coefficient of the sampling instant at which the linear equalizer 402 is based on the obtained channel response of the subsequent sampling instant. In addition, the channel response of the sampling time of ⁇ is set to the channel response at the current sampling time. If the amount of change is less than the channel change threshold, coefficient calculation module 4031 maintains the coefficients of linear equalizer 402 at the current sampling instant. At each sampling instant, the operations of the delta calculation module 4032 and the first comparison module 4033 can be repeatedly executed until one frame of the ultrasonic signal ends.
  • the adjuster 403 can further include a coefficient update module 4034, a threshold determination module 4035, a second comparison module 4036, and a zeroing module 4037.
  • the coefficient update module 4034 may update the coefficients of the linear equalizer 402 at the current sampling instant using the least mean square based adaptive estimation when the amount of change obtained by the delta calculation module 4033 is less than the channel change threshold.
  • Threshold determination module 4035 determines a first threshold for zeroing the coefficient based on the updated coefficients of linear equalizer 402.
  • the first threshold can be determined to be linear
  • the absolute value of the maximum of the updated coefficients of the scale 402 is 0.1.
  • the second comparison module 4036 compares the updated respective coefficients of the linear equalizer 402 with the first threshold, and sets the updated coefficients of the linear equalizer 402 that are less than the first threshold to zero by the zeroing module 4037.
  • the second comparison module 4036 compares the absolute values of the coefficients of the linear equalizer 402 with a first threshold and sets the coefficients of the linear equalizer 402 whose absolute value is less than the first threshold by the zeroing module 4037. Zero.
  • the channel estimation and equalization apparatus 400 for ultrasonic communication of the present embodiment is operationally capable of realizing the channel estimation and equalization method for ultrasonic communication of the embodiment shown in Figs.
  • the channel estimation and equalization apparatus 400 for ultrasonic communication of the above embodiment may be included in the mobile terminal to perform channel estimation and equalization on the ultrasonic signals mixed in the audio signal.
  • the methods of the above disclosed embodiments can be implemented in software, hardware, or a combination of software and hardware.
  • the hardware part can be implemented using dedicated logic.
  • the apparatus for providing enhanced audio data streams and its various components in the above embodiments may be comprised of semiconductors such as very large scale integrated circuits or gate arrays, such as logic chips, transistors, etc., or such as field programmable gate arrays, programmable logic
  • the hardware circuit implementation of the programmable hardware device such as a device can also be implemented by software executed by various types of processors, or by a combination of the above hardware circuits and software.
  • the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor, personal computer (PC) or mainframe.

Abstract

L'invention concerne un procédé d'estimation de canaux et d'égalisation pour communication ultrasonique, comportant les étapes consistant: en réaction à la réception d'un signal ultrasonique, à estimer une réponse de canal; à égaliser le signal ultrasonique en se basant sur la réponse estimée de canal à l'aide d'un égaliseur linéaire; et à régler un coefficient de égaliseur linéaire en fonction d'une variation de la réponse de canal. L'invention concerne en outre un appareil correspondant d'estimation de canaux et d'égalisation pour communication ultrasonique.
PCT/CN2013/073256 2013-03-27 2013-03-27 Procédé et appareil d'estimation de canaux et d'égalisation pour communication ultrasonique WO2014153732A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN201380073758.1A CN105052101A (zh) 2013-03-27 2013-03-27 用于超声波通信的信道估计和均衡方法及装置
PCT/CN2013/073256 WO2014153732A1 (fr) 2013-03-27 2013-03-27 Procédé et appareil d'estimation de canaux et d'égalisation pour communication ultrasonique
HK15112094.3A HK1211396A1 (en) 2013-03-27 2015-12-08 Channel estimating and equalizing method and apparatus for ultrasonic communication

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2013/073256 WO2014153732A1 (fr) 2013-03-27 2013-03-27 Procédé et appareil d'estimation de canaux et d'égalisation pour communication ultrasonique

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HK (1) HK1211396A1 (fr)
WO (1) WO2014153732A1 (fr)

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CN1479501A (zh) * 2002-08-28 2004-03-03 ���ǵ�����ʽ���� 用于改善均衡速度的单载波接收机的均衡器及其均衡方法
US20050053129A1 (en) * 2003-03-12 2005-03-10 Yousef Nabil R. Sparse channel dual-error tracking adaptive filter/equalizer
CN1574803A (zh) * 2003-06-24 2005-02-02 三星电子株式会社 用于数字广播信号接收系统的均衡装置和方法
CN1790902A (zh) * 2004-12-13 2006-06-21 上海无线通信研究中心 一种自适应滤波方法及装置
CN101390299A (zh) * 2006-01-24 2009-03-18 诺基亚公司 用于针对稀疏信道实现分路均衡器滤波器的装置和方法
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CN105052101A (zh) 2015-11-11
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