WO2016061975A1 - 一种误差矢量幅度系列参数确定方法和装置 - Google Patents

一种误差矢量幅度系列参数确定方法和装置 Download PDF

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WO2016061975A1
WO2016061975A1 PCT/CN2015/074046 CN2015074046W WO2016061975A1 WO 2016061975 A1 WO2016061975 A1 WO 2016061975A1 CN 2015074046 W CN2015074046 W CN 2015074046W WO 2016061975 A1 WO2016061975 A1 WO 2016061975A1
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measurement signal
offset
signal
meas
normalized
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PCT/CN2015/074046
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French (fr)
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沈百林
武成宾
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中兴通讯股份有限公司
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems

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  • the invention relates to an optical communication technology, in particular to a method and a device for determining an error vector magnitude series parameter.
  • EVM Error Vector Magnitude
  • the EVM series parameters of the IEC specification also include the following parameters:
  • the amplitude error is as follows:
  • the angle error is as follows:
  • the In-phase Quadrature (IQ) gain imbalance is as follows:
  • the IQ offset is as follows:
  • the orthogonal angle error is as follows:
  • the IEC EVM series specification has the following disadvantages: the ideal signal and the normalized measurement signal power are different, resulting in inaccurate EVM; IQ gain imbalance does not remove the IQ offset, resulting in inaccurate IQ gain imbalance; and, quadrature phase The error calculation is too complicated.
  • embodiments of the present invention provide a method and apparatus for determining an error vector magnitude series parameter.
  • the embodiment of the invention provides a method for determining an error vector magnitude series parameter, the method comprising:
  • a quadrature phase error is calculated based on the canceled IQ offset measurement signal.
  • the normalizing the measured signal by the power to obtain the normalized measurement signal is:
  • the EVM is calculated as:
  • the calculating the IQ offset according to the normalized measurement signal is:
  • the eliminating the IQ offset and obtaining the IQ offset measurement signal is:
  • the calculating the IQ gain imbalance according to the canceling the IQ offset measurement signal is:
  • Adopt formula An IQ gain imbalance is calculated, wherein the ⁇ represents the IQ gain imbalance.
  • the quadrature phase error is calculated as:
  • Adopt formula A quadrature phase error is calculated, wherein the ⁇ represents the quadrature phase error.
  • An embodiment of the present invention provides an apparatus for determining an error vector magnitude series parameter, where the apparatus includes:
  • a processing unit configured to normalize the measured signal by power to obtain a normalized measurement signal
  • a quadrature phase error is calculated based on the canceled IQ offset measurement signal.
  • the processing unit is configured to adopt a formula Normalizing the measurement signal by power to obtain a normalized measurement signal, wherein the S meas represents the normalized measurement signal, and the V meas represents the measurement signal, and the measurement signal is passed Obtaining the initial signal to be tested, wherein N is the number of samples of the measurement signal;
  • processing unit is configured to adopt a formula Calculating an IQ offset, wherein the IQ offset represents the IQ offset;
  • Adopt formula An IQ gain imbalance is calculated, wherein the ⁇ represents the IQ gain imbalance.
  • processing unit is configured to adopt a formula A quadrature phase error is calculated, wherein the ⁇ represents the quadrature phase error.
  • the acquiring unit and the processing unit may use a central processing unit (CPU), a digital signal processor (DSP), or a programmable logic array (FPGA, Field-Programmable Gate) when performing processing. Array) implementation.
  • CPU central processing unit
  • DSP digital signal processor
  • FPGA programmable logic array
  • FPGA Field-Programmable Gate
  • the technical solution of the embodiment of the present invention includes: acquiring a measurement signal; normalizing the measurement signal according to power to obtain a normalized measurement signal; and calculating according to the normalized measurement signal and the ideal signal An error vector magnitude EVM; calculating an IQ offset according to the normalized measurement signal; eliminating the IQ offset to obtain an IQ offset measurement signal; and calculating an IQ gain according to the canceling the IQ offset measurement signal balance.
  • the invention adopts a method of normalizing the obtained measurement signals by power, avoiding the problem that the ideal signal and the normalized measurement signal power are different, improving the accuracy of the EVM; and, the IQ gain imbalance removes the IQ offset Thereby, the accuracy of the IQ gain imbalance is improved; moreover, the present invention overcomes the problem that the calculation of the quadrature phase error is too complicated in the prior art.
  • FIG. 1 is a schematic flow chart of an embodiment of a method for determining an error vector magnitude series parameter according to the present invention
  • Figure 2 is a 16QAM constellation diagram
  • Figure 3 is a QPSK constellation diagram
  • FIG. 4 is a schematic diagram of an embodiment of an error vector magnitude series parameter determining apparatus according to the present invention. Schematic;
  • FIG. 5 is a schematic structural diagram of an application example of an error vector magnitude series parameter determining apparatus according to the present invention.
  • the invention provides an error vector magnitude series parameter determining method, as shown in FIG. 1 , the method includes:
  • Step 101 Acquire a measurement signal.
  • the measurement signal is obtained by calibrating the initial signal to be tested
  • the initial signal to be tested may be calibrated by the receiver, including compensation for signal reception impairments and compensation of phase noise.
  • Step 102 normalize the measurement signal by power to obtain a normalized measurement signal
  • the measuring signal is normalized by power to obtain a normalized measurement signal, which is:
  • Adopt formula Normalizing the measurement signal by power to obtain a normalized measurement signal wherein the S meas represents the normalized measurement signal, the V meas represents the measurement signal, and the N is the The number of samples of the measured signal;
  • normalization is the basis of the EVM series parameter calculation, and normalization by power can ensure that the measured signal has the same power as the ideal signal.
  • the number of samples of the measurement signal can be more than 10,000.
  • Step 103 calculating an error vector magnitude EVM according to the normalized measurement signal and the ideal signal
  • the calculating the EVM according to the normalized measurement signal and the ideal signal is:
  • Adopt formula Calculating an error vector magnitude EVM, wherein the S ideal represents the ideal signal
  • the normalized ideal signal of QPSK is The ideal signal for 16QAM is
  • the ideal signal refers to an ideal signal corresponding to the measurement signal obtained by calibrating the initial signal to be tested, instead of an ideal signal corresponding to the initial signal to be tested.
  • Figure 2 is a 16QAM constellation diagram in which the linear value of the IQ gain imbalance is 0.75 and the orthogonal angle error is 10 degrees. The constellation point in the upper right corner is taken as an example.
  • the ideal signal should be If the processing is performed according to the ideal signal corresponding to the initial signal to be tested, some signals may fall into Cause calculation errors.
  • the EVM described in the present invention includes a root mean square value and an instantaneous value.
  • the QPSK modulated signal can be simplified to:
  • the 16QAM modulated signal can be simplified to:
  • the real representation takes the real part of the complex number, the imag represents the imaginary part of the complex number, the ⁇ > represents an average value, and the
  • the amplitude error is calculated as follows:
  • phase error is calculated as follows:
  • Step 104 Calculate an IQ offset according to the normalized measurement signal.
  • the calculating the IQ offset according to the normalized measurement signal is:
  • Adopt formula An IQ offset is calculated, wherein the IQ offset represents the IQ offset, the real representation takes the real part of the complex number, the imag represents the imaginary part of the complex number, and the ⁇ > represents the averaging.
  • Step 105 Eliminate the IQ offset, and obtain an IQ offset measurement signal.
  • the eliminating the IQ offset and obtaining the IQ offset measurement signal are:
  • Step 106 Calculate an IQ gain imbalance according to the canceling the IQ offset measurement signal.
  • the calculating the IQ gain imbalance according to the canceling the IQ offset measurement signal is:
  • Adopt formula An IQ gain imbalance is calculated, wherein the ⁇ represents the IQ gain imbalance.
  • Step 107 Calculate a quadrature phase error according to the canceling the IQ offset measurement signal.
  • the calculating the quadrature phase error according to the canceling the IQ offset measurement signal is:
  • Adopt formula Calculating a quadrature phase error where ⁇ represents the quadrature phase error and the (.) represents an inner product operation, with The unit vectors of the real and imaginary parts of the IQ offset measurement signal are respectively indicated.
  • the mathematical model of the IQ offset, the IQ gain imbalance, and the quadrature phase error in the embodiment of the present invention is as follows, where [I Q] is an ideal signal, [I' Q'] is a damaged signal; ⁇ is an IQ gain. Unbalanced, ⁇ is the quadrature phase error, I0 is the I offset, and Q0 is the Q offset.
  • the I and Q offsets are averaged separately for the I and Q components, then the squared average is used, and finally converted to dB.
  • the IQ gain imbalance and quadrature phase error calculation can be performed after the IQ offset is removed.
  • the square of the I signal and the Q signal are averaged, and then the ratio is the IQ gain imbalance, which can be converted into a dB value.
  • the IQ gain imbalance can also be taken as an absolute value.
  • the cosine of the angle between the unit vector I signal and the unit vector Q signal is the result of the inner product calculation, so the sine value of the inner product calculation is the quadrature phase error of IQ.
  • I in-phase signal data
  • Q quadrature phase signal data
  • the signal can be expressed as [I Q], or I+i*Q, where i represents an imaginary number, ie, the phases are 90 degrees out of phase.
  • step 106 and the step 107 is not limited in this embodiment.
  • Figure 3 shows the QPSK constellation.
  • the signal has damage caused by modulators such as Gaussian noise, IQ offset, IQ gain imbalance and quadrature phase error.
  • the IQ gain imbalance is set to 0.5 during simulation. Linear value), the quadrature phase error is 15 degrees, the data sample is 10000, the power normalization is first performed, then the IQ offset is eliminated, and the linear value of the IQ gain imbalance is calculated by the formula of the present invention is 0.5007, The cross phase error is 14.8627 degrees.
  • Embodiments of the present invention provide an error vector magnitude series parameter determining apparatus, and the error vector magnitude series parameter determining apparatus may be integrated in a receiver or may be separately set.
  • the receiver first receives an input signal, which may be delayed interference reception or coherent reception; then, photoelectrically converting the input signal to obtain an initial signal to be tested; and then calibrating the initial signal to be measured to obtain a measurement a signal, the calibration comprising compensating for signal reception impairments and compensating phase noise, the compensation signal reception impairments may include IQ offset compensation, IQ gain imbalance compensation, IQ quadrature error compensation, etc., the phase noise is a transmitter laser line Widened.
  • the device includes:
  • the obtaining unit 401 is configured to acquire a measurement signal
  • the acquisition unit 401 can acquire a measurement signal from the receiver.
  • the processing unit 402 is configured to normalize the measurement signal by power to obtain a normalized measurement signal
  • An IQ gain imbalance is calculated based on the canceled IQ offset measurement signal.
  • the processing unit 402 is further configured to calculate a quadrature phase error according to the cancel IQ offset measurement signal.
  • the processing unit 402 is specifically configured to adopt a formula Normalizing the measurement signal by power to obtain a normalized measurement signal, wherein the S meas represents the normalized measurement signal, and the V meas represents the measurement signal, and the measurement signal is passed Obtaining the initial signal to be tested, wherein N is the number of samples of the measurement signal;
  • the processing unit 402 is specifically configured to adopt a formula Calculating an IQ offset, wherein the IQ offset represents the IQ offset, the real representation takes the real part of the complex number, the imag represents the imaginary part of the complex number, and the ⁇ > represents an average value;
  • Adopt formula An IQ gain imbalance is calculated, wherein the ⁇ represents the IQ gain imbalance.
  • the processing unit 402 is configured to adopt a formula Calculating a quadrature phase error, where ⁇ represents the quadrature phase error and the (.) represents an inner product operation, with The unit vectors of the real and imaginary parts of the IQ offset measurement signal are respectively indicated.
  • the detecting unit of the receiver receives an input signal and photoelectrically converts the input signal to obtain an initial signal to be tested, and the receiving may be delayed interference receiving or coherent receiving; the receiver
  • the calibration unit calibrates the initial signal to be tested to obtain a measurement signal, the calibration includes compensating for signal reception impairment and compensating phase noise, and the compensation signal reception impairment may include IQ offset compensation and IQ gain imbalance generated by the receiver. Compensation, IQ quadrature error compensation, etc., which is caused by the transmitter laser linewidth.
  • the acquiring unit of the error vector magnitude series parameter determining apparatus acquires the measurement signal, and the processing unit of the apparatus determines the EVM series parameter according to the measurement signal.
  • the invention is applicable to a single polarization signal and a polarization multiplexed signal; the X polarization state and the Y polarization state of the polarization multiplexed signal are calculated by the same formula.
  • the EVM series parameters in the invention may include: EVM, amplitude error, phase error, IQ offset, IQ gain imbalance, quadrature phase error.
  • EVM amplitude error
  • phase error phase error
  • IQ offset IQ offset
  • IQ gain imbalance quadrature phase error
  • quadrature phase error mainly comes from the 90 degree phase control error of the Mach-Zehnder modulator.
  • the IQ gain imbalance mainly comes from The amplitude error of the modulator I and Q drivers.
  • the EVM series parameters may also include IQ skew.
  • the IQ delay mainly comes from the delay error of the modulator optical path and/or the electrical signal, and the existing eye diagram is used to test the intersection time of the I and Q data respectively.
  • the calculation method calculates the intersection time of I and Q, and the difference is IQ skew, which is a mature practical solution, so the present invention does not refer to it.
  • the technical solution of the embodiment of the present invention includes: acquiring a measurement signal; The quantity signal is normalized by power to obtain a normalized measurement signal; the error vector magnitude EVM is calculated according to the normalized measurement signal and the ideal signal; and the IQ offset is calculated according to the normalized measurement signal; Eliminating the IQ offset, an IQ offset measurement signal is obtained; and an IQ gain imbalance is calculated according to the cancel IQ offset measurement signal.
  • the invention adopts a method of normalizing the obtained measurement signals by power, avoiding the problem that the ideal signal and the normalized measurement signal power are different, improving the accuracy of the EVM; and, the IQ gain imbalance removes the IQ offset , thereby improving the accuracy of the IQ gain imbalance.
  • the present invention overcomes the problem of too complicated calculation of orthogonal angle errors in the prior art.
  • embodiments of the present invention can be provided as a method, system, or computer program product. Accordingly, the present invention can take the form of a hardware embodiment, a software embodiment, or a combination of software and hardware. Moreover, the invention can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) including computer usable program code.
  • the computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device.
  • the apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.
  • These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device.
  • the instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.
  • the technical solution of the embodiment of the present invention includes: acquiring a measurement signal; normalizing the measurement signal by power to obtain a normalized measurement signal; and calculating an error vector magnitude EVM according to the normalized measurement signal and the ideal signal And calculating an IQ offset according to the normalized measurement signal; eliminating the IQ offset to obtain an IQ offset measurement signal; and calculating an IQ gain imbalance according to the canceling the IQ offset measurement signal.
  • the invention adopts a method of normalizing the obtained measurement signals by power, avoiding the problem that the ideal signal and the normalized measurement signal power are different, improving the accuracy of the EVM; and, the IQ gain imbalance removes the IQ offset Thereby, the accuracy of the IQ gain imbalance is improved; moreover, the present invention overcomes the problem that the calculation of the quadrature phase error is too complicated in the prior art.

Abstract

本发明公开了一种误差矢量幅度系列参数确定方法和装置，其中，所述方法包括：获取测量信号；对所述测量信号按功率进行归一化，得到归一化测量信号；根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；根据所述归一化测量信号，计算得到IQ偏移；消除所述IQ偏移，得到消除IQ偏移测量信号；根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡；根据所述消除IQ偏移测量信号，计算得到正交相位误差。

Description

一种误差矢量幅度系列参数确定方法和装置 技术领域
本发明涉及光通信技术，特别是一种误差矢量幅度系列参数确定方法和装置。
背景技术
误差矢量幅度(EVM，Error Vector Magnitude)是用来衡量一个给定时刻测量信号和理想信号之间矢量差别的参数，能评估信号的损伤程度，例如，幅度误差、相位误差。目前，光通信中100Gb/s及以上速率的高级调制码型信号的质量也开始采用EVM参数进行分析。
国际电工委员会(IEC)的技术报告(TR)61282-10《光纤通信系统设计指南第10部分：用误差矢量幅度表征光矢量调制信号的质量》(2011年出版)规范了误差矢量幅度，定义EVM为下式，其中α为归一化因子，Sref表示理想信号，Smeas表示测量信号。
Figure PCTCN2015074046-appb-000001
Figure PCTCN2015074046-appb-000002
2012年IEC颁布的修订文件将归一化因子修订为下式：
Figure PCTCN2015074046-appb-000003
IEC规范的EVM系列参数还包括以下参数：
幅度误差为下式：
Figure PCTCN2015074046-appb-000004
Figure PCTCN2015074046-appb-000005
角度误差为下式：
Figure PCTCN2015074046-appb-000006
Figure PCTCN2015074046-appb-000007
同相正交(In-phase Quadrature，IQ)增益不平衡为下式：
Figure PCTCN2015074046-appb-000008
Figure PCTCN2015074046-appb-000009
IQ偏移为下式：
Figure PCTCN2015074046-appb-000010
Figure PCTCN2015074046-appb-000011
正交角度误差为下式：
Figure PCTCN2015074046-appb-000012
Figure PCTCN2015074046-appb-000013
Figure PCTCN2015074046-appb-000014
Figure PCTCN2015074046-appb-000015
国际电信联盟(ITU-T)第15研究组(SG15)的第2工作组(WP2)的光通信系统及子系统小组也在研究制定EVM的规范，具体技术方案仍在讨论中。
IEC的EVM系列规范存在如下缺点：理想信号和归一化的测量信号功率不相同，导致EVM不准确；IQ增益不平衡未去除IQ偏移，导致IQ增益不平衡不准确；以及，正交相位误差计算过于复杂。
发明内容
为解决现有存在的技术问题，本发明实施例提供一种误差矢量幅度系列参数确定方法和装置。
本发明实施例提供了一种误差矢量幅度系列参数确定方法，所述方法包括：
获取测量信号；
对所述测量信号按功率进行归一化，得到归一化测量信号；
根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
根据所述归一化测量信号，计算得到IQ偏移；
消除所述IQ偏移，得到消除IQ偏移测量信号；
根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡；
根据所述消除IQ偏移测量信号，计算得到正交相位误差。
其中，所述对所述测量信号按功率进行归一化，得到归一化测量信号，为：
采用公式
Figure PCTCN2015074046-appb-000016
对所述测量信号按功率进行归一化，得 到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述测量信号是通过对初始待测信号进行校准得到的，所述N为所述测量信号的样本数量；
相应的，所述根据所述归一化测量信号和理想信号，计算得到EVM，为：
采用公式
Figure PCTCN2015074046-appb-000017
计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号。
其中，所述根据所述归一化测量信号，计算得到IQ偏移，为：
采用公式
Figure PCTCN2015074046-appb-000018
计算得到IQ偏移，其中，所述IQoffset表示所述IQ偏移；
所述消除所述IQ偏移，得到消除IQ偏移测量信号，为：
采用公式S1＝real(Smeas)-<real(Smeas)>+i*(imag(Smeas)-<imag(Smeas)>)消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号；
相应的，所述根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡，为：
采用公式
Figure PCTCN2015074046-appb-000019
计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
其中，所述根据所述消除IQ偏移测量信号，计算得到正交相位误差，为：
采用公式
Figure PCTCN2015074046-appb-000020
计算得到正交相位误差，其中，所述θ表示所述正交相位误差。
本发明实施例提供一种误差矢量幅度系列参数确定装置，所述装置包括：
获取单元，配置为获取测量信号；
处理单元，配置为对所述测量信号按功率进行归一化，得到归一化测量信号；
根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
根据所述归一化测量信号，计算得到IQ偏移；
消除所述IQ偏移，得到消除IQ偏移测量信号；
根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡；
根据所述消除IQ偏移测量信号，计算得到正交相位误差。
其中，所述处理单元，配置为采用公式
Figure PCTCN2015074046-appb-000021
对所述测量信号按功率进行归一化，得到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述测量信号是通过对初始待测信号进行校准得到的，所述N为所述测量信号的样本数量；以及，
采用公式
Figure PCTCN2015074046-appb-000022
计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号。
其中，所述处理单元，配置为采用公式
Figure PCTCN2015074046-appb-000023
计算得到IQ偏移，其中，所述IQoffset表示所述IQ偏移；以及，
采用公式S1＝real(Smeas)-<real(Smeas)>+i*(imag(Smeas)-<imag(Smeas)>)消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号；以及，
采用公式
Figure PCTCN2015074046-appb-000024
计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
其中，所述处理单元，配置为采用公式
Figure PCTCN2015074046-appb-000025
计算得到正交相位误差，其中，所述θ表示所述正交相位误差。
所述获取单元、所述处理单元在执行处理时，可以采用中央处理器(CPU，Central Processing Unit)、数字信号处理器(DSP，Digital Singnal Processor)或可编程逻辑阵列(FPGA，Field－Programmable Gate Array)实现。
由上可知，本发明实施例的技术方案包括：获取测量信号；对所述测量信号按功率进行归一化，得到归一化测量信号；根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；根据所述归一化测量信号，计算得到IQ偏移；消除所述IQ偏移，得到消除IQ偏移测量信号；根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡。本发明采用对获取的测量信号按功率进行归一化的方式，避免出现理想信号和归一化的测量信号功率不相同的问题，提高EVM的准确性；并且，IQ增益不平衡去除IQ偏移，从而提高IQ增益不平衡的准确性；此外，本发明克服了现有技术中正交相位误差计算过于复杂的问题。
附图说明
图1为本发明提供的一种误差矢量幅度系列参数确定方法的实施例的流程示意图；
图2为16QAM星座图；
图3为QPSK星座图；
图4为本发明提供的一种误差矢量幅度系列参数确定装置的实施例的 结构示意图；
图5为本发明提供的一种误差矢量幅度系列参数确定装置的应用实例的结构示意图。
具体实施方式
本发明提供的一种误差矢量幅度系列参数确定方法，如图1所示，所述方法包括：
步骤101、获取测量信号；
这里，所述测量信号是通过对初始待测信号进行校准得到的；
在实际应用中，可以由接收机对初始待测信号进行校准，所述校准包括补偿信号接收损伤和补偿相位噪声。
步骤102、对所述测量信号按功率进行归一化，得到归一化测量信号；
具体的，所述对所述测量信号按功率进行归一化，得到归一化测量信号，为：
采用公式
Figure PCTCN2015074046-appb-000026
对所述测量信号按功率进行归一化，得到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述N为所述测量信号的样本数量；
这里，需要说明的是，归一化是EVM系列参数计算的基础，按功率进行归一化可以保证测量信号与理想信号的功率相同。测量信号的样本数量可以为10000个以上。
步骤103、根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
具体的，所述根据所述归一化测量信号和理想信号，计算得到EVM，为：
采用公式
Figure PCTCN2015074046-appb-000027
计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号；
QPSK的归一化理想信号为
Figure PCTCN2015074046-appb-000028
16QAM的理想信号为
Figure PCTCN2015074046-appb-000029
这里，要说明的是，所述理想信号是指对初始待测信号进行校准得到的所述测量信号对应的理想信号，而不是初始待测信号对应的理想信号。图2是16QAM星座图，其中IQ增益不平衡的线性值为0.75，正交角度误差10度，以最右上角的星座点为例进行说明，其理想信号应是
Figure PCTCN2015074046-appb-000030
如果按初始待测信号对应的理想信号进行处理，则可能有部分信号落入
Figure PCTCN2015074046-appb-000031
造成计算误差。
此外，还要说明的是，本发明中所述EVM包括均方根值和瞬时值。所述EVMrms为均方根值，每个信号的EVM瞬时值为：EVM(n)＝|Smeas(n)-Sidesl(n)|；
可以理解的是，当发送端信号损伤较小时，或应用于接收信号质量检测时，上述EVMrms计算还可以简化，具体的，
QPSK调制信号可简化为：
Figure PCTCN2015074046-appb-000032
16QAM调制信号可简化为：
Figure PCTCN2015074046-appb-000033
所述real表示取复数的实部，所述imag表示取复数的虚部，所述< >表示取平均值，所述| |表示取绝对值；
在实际应用中，还可以计算EVM系列参数中的其他参数，如幅度误差和相位误差，其中，
幅度误差计算如下：
Figure PCTCN2015074046-appb-000034
相位误差计算如下：
Figure PCTCN2015074046-appb-000035
步骤104、根据所述归一化测量信号，计算得到IQ偏移；
具体的，所述根据所述归一化测量信号，计算得到IQ偏移，为：
采用公式
Figure PCTCN2015074046-appb-000036
计算得到IQ偏移，其中，所述IQoffset表示所述IQ偏移，所述real表示取复数的实部，所述imag表示取复数的虚部，所述<>表示取平均值。
这里，上式
Figure PCTCN2015074046-appb-000037
仅适用于括号内数值大于0的情况；当IQ无偏移时，括号内数值为0，此时可为IQoffset设置一个较大的负值，例如-100dB。
步骤105、消除所述IQ偏移，得到消除IQ偏移测量信号；
具体的，所述消除所述IQ偏移，得到消除IQ偏移测量信号，为：
采用公式S1＝real(Smeas)-<real(Smeas)>+i*(imag(Smeas)-<imag(Smeas)>)消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号。
步骤106、根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡。
具体的，所述根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡，为：
采用公式
Figure PCTCN2015074046-appb-000038
计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
步骤107、根据所述消除IQ偏移测量信号，计算得到正交相位误差。
具体的，所述根据所述消除IQ偏移测量信号，计算得到正交相位误差，为：
采用公式
Figure PCTCN2015074046-appb-000039
计算得到正交相位误差，其中，θ表示所述正交相位误差，所述(.)表示内积运算，
Figure PCTCN2015074046-appb-000040
和
Figure PCTCN2015074046-appb-000041
分别表示所述消除IQ偏移测量信号的实部和虚部的单位向量。
本发明实施例中IQ偏移、IQ增益不平衡以及正交相位误差等损伤的数学模型如下，其中[I Q]为理想信号，[I’ Q’]为有损伤的信号；β为IQ增益不平衡，θ为正交相位误差，I0为I偏移，Q0为Q偏移。
Figure PCTCN2015074046-appb-000042
对I分量和Q分量分别进行平均即可获得I和Q偏移量，然后再采用平方平均，最后可转换为dB。
移除IQ偏移量后才能进行IQ增益不平衡、正交相位误差的计算。对I信号和Q信号平方取均值，然后其比值则为IQ增益不平衡，可转换为dB值。考虑到EVM测量时可能无法区分I和Q，因此也可将IQ增益不平衡取绝对值。
在内积空间中，单位向量I信号和单位向量Q信号的夹角的余弦值就是其内积计算结果，因此内积计算的正弦值就是IQ的正交相位误差。
这里需要说明的是，本发明中I表示同相(In-phase)信号数据，Q表示正交相位(Quadrature)信号数据。信号可表示为[I Q]，或I+i*Q，其中i表示虚数，即相位相差90度。
这里，需要强调的是，本实施例中对所述步骤106和所述步骤107的执行顺序不做限定。
下面再举一个计算示例，图3为QPSK星座图，信号有高斯噪声、IQ偏移、IQ增益不平衡和正交相位误差等调制器带来的损伤，仿真时设置IQ增益不平衡为0.5(线性值)，正交相位误差为15度，数据样本为10000个，首先进行功率归一化，然后消除IQ偏移，利用本发明所述公式计算出IQ增益不平衡的线性值为0.5007，正交相位误差为14.8627度。
本发明实施例提供了一种误差矢量幅度系列参数确定装置，所述误差矢量幅度系列参数确定装置可以集成在接收机中，也可以单独设置。所述接收机首先接收输入信号，可以是延迟干涉接收，也可以是相干接收；接着，对所述输入信号进行光电转换得到初始待测信号；然后，对所述初始待测信号进行校准得到测量信号，所述校准包括补偿信号接收损伤和补偿相位噪声，所述补偿信号接收损伤可以包括IQ偏移补偿、IQ增益不平衡补偿、IQ正交误差补偿等，所述相位噪声是发射机激光器线宽导致的。
如图4所示，所述装置包括：
获取单元401，配置为获取测量信号；
这里，所述获取单元401可以从所述接收机获取测量信号。
处理单元402，配置为对所述测量信号按功率进行归一化，得到归一化测量信号；
根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
根据所述归一化测量信号，计算得到IQ偏移；
消除所述IQ偏移，得到消除IQ偏移测量信号；
根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡。
在一实施例中，所述处理单元402，还配置为根据所述消除IQ偏移测量信号，计算得到正交相位误差。
具体的，所述处理单元402，具体配置为采用公式
Figure PCTCN2015074046-appb-000043
对所述测量信号按功率进行归一化，得到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述测量信号是通过对初始待测信号进行校准得到的，所述N为所述测量信号的样本数量；以及，
采用公式
Figure PCTCN2015074046-appb-000044
计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号。
具体的，所述处理单元402，具体配置为采用公式
Figure PCTCN2015074046-appb-000045
计算得到IQ偏移，其中，所述IQoffset表示所述IQ偏移，所述real表示取复数的实部，所述imag表示取复数的虚部，所述<>表示取平均值；以及，
采用公式S1＝real(Smeas)-<real(Smeas)>+i*(imag(Smeas)-<imag(Smeas)>)消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号；以及，
采用公式
Figure PCTCN2015074046-appb-000046
计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
具体的，所述处理单元402，配置为采用公式
Figure PCTCN2015074046-appb-000047
计算得到正交相位误差，其中，θ表示所述正 交相位误差，所述(.)表示内积运算，
Figure PCTCN2015074046-appb-000048
和
Figure PCTCN2015074046-appb-000049
分别表示所述消除IQ偏移测量信号的实部和虚部的单位向量。
下面对本发明实施例提供的误差矢量幅度系列参数确定装置内置于接收机的应用实例进行介绍。
如图5所示，所述接收机的探测单元接收输入信号并对所述输入信号进行光电转换得到初始待测信号，所述接收可以是延迟干涉接收，也可以是相干接收；所述接收机的校准单元对所述初始待测信号进行校准得到测量信号，所述校准包括补偿信号接收损伤和补偿相位噪声，所述补偿信号接收损伤可以包括接收机产生的IQ偏移补偿、IQ增益不平衡补偿、IQ正交误差补偿等，所述相位噪声是发射机激光器线宽导致的。本发明提供的误差矢量幅度系列参数确定装置的获取单元获取所述测量信号，所述装置的处理单元根据所述测量信号确定EVM系列参数。
本发明适用于单偏振信号和偏振复用信号；偏振复用信号中X偏振态和Y偏振态采用相同的公式进行计算。
发明中的EVM系列参数可以包括：EVM、幅度误差、相位误差、IQ偏移、IQ增益不平衡、正交相位误差。这是因为，在很多应用场景下，除EVM外，还需对IQ增益不平衡性、IQ偏移、正交相位误差进行进一步分析。其中，IQ偏移主要来自马赫-泽德调制器的I向量或Q向量的偏移不正确，正交相位误差主要来自于马赫-泽德调制器90度相位控制误差，IQ增益不平衡主要来自于调制器I和Q路驱动器的幅度误差。
此外，EVM系列参数还可以包括IQ时延(IQ skew)，IQ时延主要来自调制器光路和/或电信号的时延误差，对I和Q数据分别采用现有眼图测试交叉点时间的计算方法，计算出I和Q交叉点时间，其差即为IQ skew，此为成熟实用方案，故本发明不予涉及。
综上所述，本发明实施例的技术方案包括：获取测量信号；对所述测 量信号按功率进行归一化，得到归一化测量信号；根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；根据所述归一化测量信号，计算得到IQ偏移；消除所述IQ偏移，得到消除IQ偏移测量信号；根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡。本发明采用对获取的测量信号按功率进行归一化的方式，避免出现理想信号和归一化的测量信号功率不相同的问题，提高EVM的准确性；并且，IQ增益不平衡去除IQ偏移，从而提高IQ增益不平衡的准确性。此外，本发明克服了现有技术中正交角度误差计算过于复杂的问题。
本领域内的技术人员应明白，本发明的实施例可提供为方法、系统、或计算机程序产品。因此，本发明可采用硬件实施例、软件实施例、或结合软件和硬件方面的实施例的形式。而且，本发明可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器和光学存储器等)上实施的计算机程序产品的形式。
本发明是参照根据本发明实施例的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器，使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中，使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品，该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上，使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理，从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
以上所述，仅为本发明的较佳实施例而已，并非用于限定本发明的保护范围。
工业实用性
本发明实施例的技术方案包括：获取测量信号；对所述测量信号按功率进行归一化，得到归一化测量信号；根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；根据所述归一化测量信号，计算得到IQ偏移；消除所述IQ偏移，得到消除IQ偏移测量信号；根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡。本发明采用对获取的测量信号按功率进行归一化的方式，避免出现理想信号和归一化的测量信号功率不相同的问题，提高EVM的准确性；并且，IQ增益不平衡去除IQ偏移，从而提高IQ增益不平衡的准确性；此外，本发明克服了现有技术中正交相位误差计算过于复杂的问题。

Claims (8)

  1. 一种误差矢量幅度系列参数确定方法，所述方法包括：
    获取测量信号；
    对所述测量信号按功率进行归一化，得到归一化测量信号；
    根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
    根据所述归一化测量信号，计算得到IQ偏移；
    消除所述IQ偏移，得到消除IQ偏移测量信号；
    根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡；
    根据所述消除IQ偏移测量信号，计算得到正交相位误差。
  2. 根据权利要求1所述的方法，其中，所述对所述测量信号按功率进行归一化，得到归一化测量信号，为：
    采用公式
    Figure PCTCN2015074046-appb-100001
    对所述测量信号按功率进行归一化，得到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述测量信号是通过对初始待测信号进行校准得到的，所述N为所述测量信号的样本数量；
    相应的，所述根据所述归一化测量信号和理想信号，计算得到EVM，为：
    采用公式
    Figure PCTCN2015074046-appb-100002
    计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号。
  3. 根据权利要求1所述的方法，其中，所述根据所述归一化测量信号，计算得到IQ偏移，为：
    采用公式
    Figure PCTCN2015074046-appb-100003
    计算得到IQ偏移， 其中，所述IQoffset表示所述IQ偏移；
    所述消除所述IQ偏移，得到消除IQ偏移测量信号，为：
    采用公式S1＝real(Smeas)-(real(Smeas))+i*(imag(Smeas)-(imag(Smeas)))消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号；
    相应的，所述根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡，为：
    采用公式
    Figure PCTCN2015074046-appb-100004
    计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
  4. 根据权利要求1所述的方法，其中，所述根据所述消除IQ偏移测量信号，计算得到正交相位误差，为：
    采用公式
    Figure PCTCN2015074046-appb-100005
    计算得到正交相位误差，其中，所述θ表示所述正交相位误差。
  5. 一种误差矢量幅度系列参数确定装置，所述装置包括：
    获取单元，配置为获取测量信号；
    处理单元，配置为对所述测量信号按功率进行归一化，得到归一化测量信号；
    根据所述归一化测量信号和理想信号，计算得到误差矢量幅度EVM；
    根据所述归一化测量信号，计算得到IQ偏移；
    消除所述IQ偏移，得到消除IQ偏移测量信号；
    根据所述消除IQ偏移测量信号，计算得到IQ增益不平衡；
    根据所述消除IQ偏移测量信号，计算得到正交相位误差。
  6. 根据权利要求5所述的装置，其中，所述处理单元，配置为采用公 式
    Figure PCTCN2015074046-appb-100006
    对所述测量信号按功率进行归一化，得到归一化测量信号，其中，所述Smeas表示所述归一化测量信号，所述Vmeas表示所述测量信号，所述测量信号是通过对初始待测信号进行校准得到的，所述N为所述测量信号的样本数量；以及，
    采用公式
    Figure PCTCN2015074046-appb-100007
    计算得到误差矢量幅度EVM，其中，所述Sideal表示所述理想信号。
  7. 根据权利要求5所述的装置，其中，所述处理单元，配置为采用公式
    Figure PCTCN2015074046-appb-100008
    计算得到IQ偏移，其中，所述IQoffset表示所述IQ偏移；以及，
    采用公式S1＝real(Smeas)-(real(Smeas))+i*(imag(Smeas)-(imag(Smeas)))消除所述IQ偏移，得到消除IQ偏移测量信号，其中，所述S1表示所述消除IQ偏移测量信号；以及，
    采用公式
    Figure PCTCN2015074046-appb-100009
    计算得到IQ增益不平衡，其中，所述β表示所述IQ增益不平衡。
  8. 根据权利要求5所述的装置，其中，所述处理单元，配置为采用公式
    Figure PCTCN2015074046-appb-100010
    计算得到正交相位误差，其中，所述θ表示所述正交相位误差。
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