WO2012155463A1 - Procédé et dispositif de synchronisation de système - Google Patents

Procédé et dispositif de synchronisation de système Download PDF

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Publication number
WO2012155463A1
WO2012155463A1 PCT/CN2011/081757 CN2011081757W WO2012155463A1 WO 2012155463 A1 WO2012155463 A1 WO 2012155463A1 CN 2011081757 W CN2011081757 W CN 2011081757W WO 2012155463 A1 WO2012155463 A1 WO 2012155463A1
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WO
WIPO (PCT)
Prior art keywords
pilot
symbol
time
frequency
carrier
Prior art date
Application number
PCT/CN2011/081757
Other languages
English (en)
Chinese (zh)
Inventor
李静
Original Assignee
中兴通讯股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 中兴通讯股份有限公司 filed Critical 中兴通讯股份有限公司
Publication of WO2012155463A1 publication Critical patent/WO2012155463A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2662—Symbol synchronisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2668—Details of algorithms
    • H04L27/2681—Details of algorithms characterised by constraints
    • H04L27/2684—Complexity

Definitions

  • the present invention relates to the field of communications, and in particular, to a method and apparatus for synchronizing MIMO (Multiple Input Multiple-Output) (MIMO) in an OFDM (Orthogonal Frequency Division Multiplex) system.
  • MIMO Multiple Input Multiple-Output
  • OFDM Orthogonal Frequency Division Multiplex
  • OFDM frequency division multiplexing
  • WLAN Wireless Local Area Networks
  • DAB Digital Audio Broadcasting
  • DVB Digital Video Broadcasting
  • the IEEE 802.16 working group adopted OFDM technology as its transmission technology in its air interface standard.
  • MIMO technology is a major breakthrough in the smart antenna technology in the field of wireless mobile communications. It uses the increased transmission channel in space, and uses multiple antennas to transmit signals simultaneously at the transmitting end and the receiving end. Since the signals transmitted by the transmitting antennas simultaneously occupy the same frequency band, By increasing bandwidth, you can double your system capacity and spectrum utilization. Systems combining OFDM and MIMO have high transmission rates while achieving high reliability through diversity.
  • Synchronization technology is the key technology to realize OFDM system, including time-offset estimation and frequency offset estimation.
  • Time-shift and frequency offset obtained by time-offset estimation and frequency-offset estimation are important parameters reflecting system performance.
  • the wireless signal is time-varying, and the frequency offset of the wireless signal occurs during transmission, such as Doppler shift, or due to the frequency deviation between the transmitter and receiver carrier frequencies.
  • the orthogonality between subcarriers in the OFDM system is destroyed, resulting in interference between subchannels, and the signal is distorted, which seriously affects system performance. Therefore, synchronization Including time synchronization and frequency synchronization are important guarantees for system performance.
  • Time offset specifically: Calculate the time offset using the formula 1 ⁇ ⁇ ⁇ , where 1 is the time offset, N is the FFT point, M is the pilot interval, 1 is the subcarrier, and k and k+1 are the subcarrier indices. .
  • pilot conjugate multiplication requires IFFT (inverse fast Fourier transform) on all data, which leads to the method.
  • IFFT inverse fast Fourier transform
  • the computational complexity is large and wastes resources; in addition, in the method of pilot bias conjugate multiplication calculation, the time-bias deviation method is used, and the pilot bias equivalent method is used to estimate the time offset, and the value on the null carrier and the pilot carrier are considered. The same as above, this will make the original data when calculating the frequency offset not accurate enough, and then use this equivalent data to perform time-bias and frequency-offset estimation, which will make the time-offset and frequency-offset estimation values inaccurate.
  • the technical problem to be solved by the present invention is to provide a synchronization method and apparatus for MIMO in OFDM systems, which solves the problem of large computational complexity and inaccuracy in the calculation of time offset and frequency offset estimation values in the prior art.
  • the present invention provides a synchronization method for an OFDM system, the method comprising:
  • the synchronization of the OFDM system is performed according to the time offset and the frequency offset estimation value.
  • the above method wherein the finding a time offset by searching for a peak of a pilot channel response
  • the position should be: the peak position of the pilot channel response obtained after IFFT conversion of the pilot sequence.
  • the peak position of the pilot channel response is obtained by performing IFFT conversion on the pilot sequence, and the peak position of the pilot channel response is obtained after performing IFFT conversion on the pilot sequence.
  • the peak position of the pilot channel response obtained by performing IFFT conversion on the pilot sequence includes: performing IFFT on the pilot sequence P to obtain the pilot at the nth time is
  • N is the FFT point number
  • m is the pilot pilot index
  • #Pilot which is the input symbol sequence
  • ⁇ ,. is the delay, not greater than N g , i is the accumulated index, and N g is the ratio of the cyclic prefix time to the useful symbol time;
  • the obtaining the frequency offset estimation value comprises: first obtaining frequency domain receiving data on the pilot carrier, and then calculating the frequency offset estimation value by using the frequency domain receiving data.
  • the obtaining frequency domain receiving data on the pilot carrier is:: frequency domain receiving data on the mth carrier of the 0th symbol
  • ⁇ ⁇ —calculate the frequency offset estimate
  • the invention also provides a synchronization device, including
  • a peak search module configured to find a position corresponding to a time offset by a peak search of a pilot channel response
  • a frequency offset estimation module configured to obtain a frequency offset estimation value according to a phase difference between the time offset and the pilot symbol
  • a synchronization module configured to perform orthogonal frequency division multiplexing (OFDM) synchronization based on time offset and frequency offset estimation.
  • OFDM orthogonal frequency division multiplexing
  • the frequency offset estimation module is configured to first obtain frequency domain received data on a pilot carrier, and then calculate a frequency offset estimation value by using frequency domain received data.
  • the peak search module is specifically configured to calculate frequency domain receiving data by using the following formula:
  • Frequency domain receive data on the mth carrier of the 0th symbol
  • Frequency domain receive data on the mth 3th carrier of the 0th symbol
  • ⁇ 2 Frequency domain receive data on the wth carrier of the first symbol
  • P 3 Frequency domain reception data on the mth 3th carrier of the gth symbol.
  • the technical solution of the invention has the advantages of high performance and low complexity, and is easy to implement, and the advantages thereof are mainly as follows: (1) The complexity is low, because the peak search in the prior art needs to perform IFFT on all data carriers. The peak search of the present invention only needs to find the position corresponding to the pilot, and performs IFFT on the pilot carrier at the position corresponding to the pilot. Since the pilot carrier is rarely used for MIMO, it is half of the non-MIMO, so it can be reduced.
  • Figure 1 is a flow chart of an embodiment of the present invention
  • 2 is a Ptten A basic structure diagram of a MIMO subcarrier
  • Figure 3 is a diagram showing the basic structure of Patten B of a MIMO subcarrier. detailed description
  • FIG. 1 it is a flowchart of an embodiment of the present invention, which provides a synchronization method for MIMO in an OFDM system, including:
  • Step S101 Perform a peak search on the pilot signal to find a position corresponding to the time offset; the specific step is: first calculating a low-pass equivalent signal of the pilot signal; and then using the low-pass equivalent signal of the pilot signal, calculating The pilot subcarrier sequence is output; finally, the pilot subcarrier sequence is used to calculate the time offset.
  • ⁇ denotes the useful symbol time
  • ⁇ denotes the guard interval or cyclic prefix time
  • N denotes the FFT (Fast Fourier Transform) point number
  • ⁇ is the transmitted signal
  • ⁇ / is the subcarrier spacing, 7
  • N g A ratio of cyclic prefix time to useful symbol time
  • k is the sampling point
  • j is the imaginary part symbol defined in the Fourier variation expression
  • t is the starting time
  • ⁇ / according to the OFDM system definition
  • R n exp [2 ⁇ 'kn/N]
  • Step S102 The frequency offset estimation value is obtained according to the phase difference between the time offset and the pilot symbol.
  • the step is specifically: first obtaining frequency domain receiving data on the pilot carrier, and then calculating the frequency offset estimation value by using the frequency domain receiving data;
  • the obtaining the frequency domain receiving data on the pilot carrier may be: when the MIMO subcarrier is the Patten A shown in FIG. 2, the figure includes three types: a null carrier, a pilot carrier, and a data carrier.
  • the shaded circle represents the pilot carrier, the horizontal shaded circle represents the empty carrier, and the remaining blank circles represent the digital carrier, where the two pilot carriers are respectively, or may be:
  • the MIMO subcarrier is the Patten B shown in FIG. 3
  • the figure It includes three types: null carrier, pilot carrier and data carrier.
  • the oblique hatched circle indicates the pilot carrier
  • the horizontal hatched circle indicates the null carrier
  • the remaining blank circles indicate the digital carrier
  • the two pilot carriers are respectively ⁇ . , among them, .
  • the data received in the frequency domain on the wth carrier of the 0th symbol can be expressed by the following formula:
  • the data received in the frequency domain on the +3th carrier of the 0th symbol can be expressed by the following formula: ex V (-j2 ⁇ (m + 3)/N) ⁇ d i0 ⁇ exp /1 ⁇ ⁇ - ⁇
  • the data is received in the frequency domain on the wth carrier of the first symbol, which can be expressed by the following formula:
  • the data received in the frequency domain on the +3th carrier of the gth symbol can be expressed by the following formula: exp(-j2 ⁇ (m + 3)/N) - exp(72 ⁇ r ⁇ -) , d iq ⁇ ⁇ exp ]1 ⁇ ⁇ -—— - ;
  • N the number of points of Fi
  • T T b + T g
  • T b N
  • T g -N
  • Step S103 Perform synchronization of the OFDM system according to the time offset and the frequency offset estimation value.
  • the present invention also provides an embodiment of a synchronization device, specifically including a peak search module, configured to find a position corresponding to a time offset by a peak search of a pilot channel response;
  • a frequency offset estimation module configured to obtain a frequency offset estimation value according to a phase difference between the time offset and the pilot symbol
  • a synchronization module is configured to perform synchronization of the OFDM system according to the time offset and the frequency offset estimation value.
  • the peak search module is specifically configured to perform IFFT conversion on the pilot sequence, and calculate a peak position of the pilot channel response;
  • the peak position of the pilot channel response can be calculated by using the following formula:
  • the frequency offset estimation module is configured to first obtain frequency domain receiving data on a pilot carrier, and then use the frequency domain receiving data to calculate a frequency offset estimation value.
  • the frequency offset estimation module is specifically configured to calculate two pilot carriers when the MIMO subcarrier is the Patten A shown in FIG. 2, and when the MIMO subcarrier is the Patten B shown in FIG.
  • P 0 ⁇ (-]2 ⁇ / ⁇ ) ⁇ d i0 ⁇ exp ⁇ ]2 ⁇ ⁇ £ ⁇ + ⁇ m)
  • P, ex V (-j2 ⁇ (m + 3)/N) ⁇ d i0 ⁇ exp /1 ⁇ ⁇ - ⁇
  • the frequency offset estimation module is specifically configured to calculate a frequency offset estimation value for the pilot carrier
  • the calculating the frequency offset estimation value includes: when the MIMO format is Patten in FIG. 2
  • N the number of points of Fi
  • T T b + T g
  • T b N
  • T g -N

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Radio Transmission System (AREA)

Abstract

La présente invention concerne un procédé de synchronisation d'un système à multiplexage par répartition orthogonale de la fréquence (OFDM), comportant les étapes consistant à : repérer la position correspondant à un décalage temporel en explorant une réponse de canal pilote à la recherche d'une valeur de pic ; obtenir la valeur d'estimation du décalage en fréquence en fonction du déphasage entre le décalage temporel et un signal pilote ; et effectuer la synchronisation du système OFDM en fonction du décalage temporel et de la valeur d'estimation du décalage en fréquence. La présente invention concerne également un dispositif de synchronisation. L'application de la présente invention résout le problème, rencontré dans l'état antérieur de la technique, de l'importante charge de calcul et de l'imprécision du calcul du décalage temporel et de la valeur d'estimation du décalage en fréquence.
PCT/CN2011/081757 2011-05-17 2011-11-03 Procédé et dispositif de synchronisation de système WO2012155463A1 (fr)

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Application Number Priority Date Filing Date Title
CN201110127753.5 2011-05-17
CN201110127753.5A CN102790737B (zh) 2011-05-17 2011-05-17 一种***的同步方法及装置

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CN105282081A (zh) * 2014-06-27 2016-01-27 中兴通讯股份有限公司 一种载波频偏估计的方法及装置
CN110636024A (zh) * 2019-10-15 2019-12-31 长安大学 一种基于索引调制的5g波形***同步方法

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CN104660540B (zh) * 2013-11-21 2018-11-16 展讯通信（上海）有限公司 一种lte***的同步跟踪方法
CN110336584A (zh) * 2019-06-13 2019-10-15 大连理工大学 基于多周期联合分析的多峰值ccsk信号自同步方法
CN110855595B (zh) * 2019-11-29 2022-04-01 紫光展讯通信(惠州)有限公司 时偏估计方法、装置、接收机及存储介质

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CN110636024B (zh) * 2019-10-15 2022-10-11 长安大学 一种基于索引调制的5g波形***同步方法

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