技术领域technical field
本发明是有关于一种通信方法及装置，且特别是有关于一种OFDM系统中同相路径及正交路径间不平衡效应的估测补偿方法及装置。The present invention relates to a communication method and device, and in particular to a method and device for estimating and compensating the imbalance effect between the in-phase path and the orthogonal path in an OFDM system.
背景技术Background technique
在无线通信系统中，由于接收端的同相路径（In-phase path,I path）与正交路径（Quadrature path,Q path）之间的相位及增益的不均衡所造成的IQ不均衡（IQimbalance）效应，为接收射频（Radio Frequency,RF）信号时所常见的问题。而上述的IQ不均衡效应在正交频分复用（Orthogonal Frequency Division Multiplexing,OFDM）通信系统中则会产生镜像干扰（image aliasing）的问题，对接收到的信号产生直接的影响，尤其当接收端为建置成本较为低廉的装置，例如机器间（Machine-to-Machine,M2M）通信中的检测节点（sensor node）时，影响更大。In a wireless communication system, the IQ imbalance (IQimbalance) effect is caused by the phase and gain imbalance between the in-phase path (I path) and the quadrature path (Quadrature path, Q path) at the receiving end. , which is a common problem when receiving radio frequency (Radio Frequency, RF) signals. However, the above-mentioned IQ imbalance effect will cause image aliasing in Orthogonal Frequency Division Multiplexing (OFDM) communication systems, which will have a direct impact on received signals, especially when receiving When the terminal is a device with relatively low construction cost, such as a detection node (sensor node) in machine-to-machine (M2M) communication, the impact is greater.
目前已知有以下几种解决上述IQ不均衡效应的作法，一为传送数据中置放较长的前置（preamble）信号或引导信号（pilot signal），藉此取得IQ路径的特性，这样的作法复杂度较低，但必须因应不同的标准作不同的处理，数据的传输率亦受到影响。另一则为利用接收到的时域（time domain）信号进行盲估测（blind estimation），这样的作法虽可适用于所有的现行标准，但需要较久的收敛时间以及较高的计算复杂度。再者则为回溯式的IQ路径估计，根据每一次的补偿结果，利用误差参数（error factor）来修正补偿内容，但这样的方法同样的需要较长的收敛时间。上述的解决方法，在解决不均衡效应的同时，往往伴随着数据传输率偏低或是复杂度过高的问题。因此，如何去除信号中的镜像干扰问题并同时兼顾系统的硬件成本及计算复杂度，此为本领域极为重要之议题。At present, the following methods are known to solve the above-mentioned IQ imbalance effect. One is to place a long preamble signal or pilot signal in the transmitted data, so as to obtain the characteristics of the IQ path. The complexity of the method is low, but it must be handled differently in response to different standards, and the data transmission rate is also affected. The other is to use the received time domain (time domain) signal to perform blind estimation (blind estimation). Although this method is applicable to all current standards, it requires a long convergence time and high computational complexity . Furthermore, it is a retrospective IQ path estimation. According to each compensation result, the error parameter (error factor) is used to correct the compensation content, but this method also requires a long convergence time. The above solutions, while solving the imbalance effect, are often accompanied by the problem of low data transmission rate or high complexity. Therefore, how to remove the image interference problem in the signal while taking into account the hardware cost and computational complexity of the system is an extremely important issue in this field.
发明内容Contents of the invention
本发明提供一种估测补偿方法及装置，以盲估测（blind estimation）频域（frequency domain）信号的方式，消除信号中IQ不均衡效应的影响。The present invention provides an estimation and compensation method and device, which can eliminate the influence of IQ unbalanced effect in the signal by means of blind estimation (frequency domain) signal.
本发明的一种估测补偿方法，适用于估测并补偿正交频分复用（OrthogonalFrequency Division Multiplexing,OFDM）通信系统中的一同相路径（In-phase path）以及一正交路径（Quadrature path）的不均衡（imbalance）效应，包括以下步骤：首先，接收一频域信号，利用频域信号中多个时间点的多个符号，产生多个均衡参数组，其中每一均衡参数组包括多个候选均衡参数；接着，根据均衡参数组得到一均衡参数；然后，根据均衡参数补偿频域信号。An estimation and compensation method of the present invention is suitable for estimating and compensating an In-phase path and a Quadrature path in an Orthogonal Frequency Division Multiplexing (OFDM) communication system ) imbalance (imbalance) effect, including the following steps: First, receive a frequency domain signal, use multiple symbols at multiple time points in the frequency domain signal to generate multiple equalization parameter groups, where each equalization parameter group includes multiple a candidate equalization parameter; then, obtain an equalization parameter according to the equalization parameter set; then, compensate the frequency domain signal according to the equalization parameter.
本发明的一种估测补偿装置，适用于估测并补偿正交频分复用通信系统中的同相路径以及正交路径的不均衡效应，包括：一估测器及一补偿器。估测器接收一频域信号，利用频域信号中多个时间点的多个符号产生多个均衡参数组，其中每一均衡参数组包括多个候选均衡参数，并且估测器根据均衡参数组得到均衡参数。补偿器耦接估测器，根据均衡参数补偿频域信号。An estimating and compensating device of the present invention is suitable for estimating and compensating the unbalanced effect of the in-phase path and the quadrature path in the OFDM communication system, comprising: an estimator and a compensator. The estimator receives a frequency domain signal, uses multiple symbols at multiple time points in the frequency domain signal to generate a plurality of equalization parameter groups, wherein each equalization parameter group includes a plurality of candidate equalization parameters, and the estimator generates a plurality of equalization parameter groups according to the equalization parameter group Get the balance parameters. The compensator is coupled to the estimator and compensates the frequency domain signal according to the equalization parameter.
基于上述，本发明提供一种估测补偿方法及装置，频域信号中从多个时间点的多个符号产生多个均衡参数组，再由候选均衡参数中得到可用以补偿IQ不均衡效应的均衡参数。Based on the above, the present invention provides a method and device for estimation and compensation. Multiple equalization parameter groups are generated from multiple symbols at multiple time points in the frequency domain signal, and then the candidate equalization parameters can be used to compensate for the IQ imbalance effect. Balance parameters.
为让本发明的上述特征和优点能更明显易懂，下文特举实施例，并配合附图作详细说明如下。In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail with reference to the accompanying drawings.
附图说明Description of drawings
图1为根据本发明一实施例所示出估测补偿方法的流程步骤图；FIG. 1 is a flow chart showing the steps of an estimation and compensation method according to an embodiment of the present invention;
图2为根据本发明一实施例所示出估测补偿装置的功能方块图；Fig. 2 is a functional block diagram showing an estimation and compensation device according to an embodiment of the present invention;
图3A、图3B及图3C为根据本发明一实施例所示出目标符号以及镜像符号对应于通信资源（communication resource）的关系示意图；FIG. 3A, FIG. 3B and FIG. 3C are schematic diagrams showing the relationship between target symbols and image symbols corresponding to communication resources (communication resource) according to an embodiment of the present invention;
图4为根据本发明一实施例所示出估测补偿方法的流程步骤图；FIG. 4 is a flow chart showing the steps of an estimation and compensation method according to an embodiment of the present invention;
图5为根据本发明一实施例所示出接收端的功能方块图。FIG. 5 is a functional block diagram of a receiver according to an embodiment of the invention.
附图标记说明：Explanation of reference signs:
S101～S103、S401～S412：步骤；S101～S103, S401～S412: steps;
20：估测补偿装置；20: Estimate compensation device;
210：估测器；210: estimator;
220：补偿器；220: compensator;
30～32：通信资源；30~32: communication resources;
50：接收端；50: receiving end;
510：前端电路；510: front-end circuit;
511：天线单元；511: antenna unit;
512：本地振荡器；512: local oscillator;
513、514：混波器；513, 514: mixer;
515、516：低通滤波器；515, 516: low-pass filter;
517、518：模拟/数字转换器；517, 518: analog/digital converter;
520：快速傅立叶转换单元；520: fast Fourier transform unit;
530：均衡器；530: equalizer;
540：解调器；540: demodulator;
D：均衡参数；D: Balance parameter;
DAT：数据；DAT: data;
R：信号（频域信号）；R: signal (frequency domain signal);
R'：补偿后频域信号；R': frequency domain signal after compensation;
OS1～OS2：目标符号；OS1～OS2: target symbol;
MS1～MS2：镜像符号；MS1～MS2: mirror image symbol;
Z：模拟时域信号；Z: Analog time domain signal;
ZI：I路径的模拟时域信号；ZI: Analog time domain signal of I path;
ZID：I路径的数字时域信号；ZID: digital time domain signal of I path;
ZQ：Q路径的模拟时域信号；ZQ: the analog time domain signal of the Q path;
ZQD：Q路径的数字时域信号。ZQD: Digital time-domain signal of the Q path.
具体实施方式Detailed ways
图1为根据本发明一实施例所示出估测补偿方法的流程步骤图，其中所述的估测补偿方法适用于估测并补偿正交频分复用通信系统中的同相路径以及正交路径的不均衡效应。请参照图1，首先在步骤S101时，接收一频域信号，利用频域信号中多个时间点的多个符号，产生多个均衡参数组，其中每一均衡参数组包括多个候选均衡参数。接着在步骤S102时，根据均衡参数组得到一均衡参数。然后在步骤S103时，根据均衡参数补偿频域信号。Fig. 1 is a flow chart showing the steps of the estimation and compensation method according to an embodiment of the present invention, wherein the estimation and compensation method is suitable for estimating and compensating the in-phase path and the quadrature path in the OFDM communication system Path disequilibrium effects. Please refer to FIG. 1. First, in step S101, a frequency-domain signal is received, and multiple symbols at multiple time points in the frequency-domain signal are used to generate multiple equalization parameter groups, wherein each equalization parameter group includes multiple candidate equalization parameters. . Then in step S102, an equalization parameter is obtained according to the equalization parameter set. Then in step S103, the frequency domain signal is compensated according to the equalization parameters.
对应于图1，图2为根据本发明一实施例所示出估测补偿装置的功能方块图，所述估测补偿装置亦适用于估测并补偿正交频分复用通信系统中的同相路径以及正交路径的不均衡效应。请参照图2，估测补偿装置20包括：估测器210及补偿器220。估测器210接收频域信号R，利用频域信号R中多个时间点的多个符号（symbol）产生多个均衡参数组，其中每一均衡参数组包括多个候选均衡参数，并且估测器210根据均衡参数组得到均衡参数D。补偿器220耦接估测器210，根据均衡参数D补偿频域信号R，得到补偿后频域信号R'。Corresponding to FIG. 1, FIG. 2 is a functional block diagram showing an estimation and compensation device according to an embodiment of the present invention, and the estimation and compensation device is also suitable for estimating and compensating the in-phase in an OFDM communication system paths as well as the disequilibrium effects of orthogonal paths. Referring to FIG. 2 , the estimation and compensation device 20 includes: an estimator 210 and a compensator 220 . The estimator 210 receives the frequency domain signal R, uses multiple symbols (symbols) at multiple time points in the frequency domain signal R to generate multiple equalization parameter groups, wherein each equalization parameter group includes multiple candidate equalization parameters, and estimates The unit 210 obtains the equalization parameter D according to the equalization parameter set. The compensator 220 is coupled to the estimator 210 and compensates the frequency domain signal R according to the equalization parameter D to obtain a compensated frequency domain signal R′.
在本发明中，估测补偿装置20可通过一处理器配合存储单元，执行程序码而实现。或者，估测补偿装置20亦可以硬件电路实现，例如以系统单芯片（system on-chip, SoC）的方式实现，并与接收端其他电路整合。在本发明中，频域信号R为基带（baseband）的频域信号，由接收电路（未绘示）接收高频射频信号后，降频为基带时域信号，再接着利用快速傅立叶转换（Fast Fourier Transform, FFT）等方式转换而得。并且，频域信号R中包括从多个子载波所接收的信号。其中，频域信号R中由第k个子载波所接收到的信号R(k)可被表示为由I路径的信号IBB(k)及Q路径的信号IBB(k)之和：In the present invention, the estimation and compensation device 20 can be implemented by a processor cooperating with a storage unit to execute program codes. Alternatively, the estimation and compensation device 20 can also be implemented as a hardware circuit, such as implemented in a system on-chip (SoC) manner, and integrated with other circuits at the receiving end. In the present invention, the frequency-domain signal R is a baseband frequency-domain signal. After receiving a high-frequency radio frequency signal by a receiving circuit (not shown), the frequency is down-converted to a baseband time-domain signal, and then fast Fourier transform (Fast Fourier Transform, FFT) and other methods. Also, the frequency domain signal R includes signals received from multiple subcarriers. Among them, the signal R(k) received by the kth subcarrier in the frequency domain signal R can be expressed as the sum of the signal IBB (k) of the I path and the signal IBB (k) of the Q path:
R(k)=IBB(k)+jQBB(k) （1）R(k)=IBB (k)+jQBB (k) (1)
经推导之后，上式（1）可改写为：After derivation, the above formula (1) can be rewritten as:
R(k)=αZ(k)+βZ*(-k)，其中R(k)=αZ(k)+βZ*(-k), where
其中，g表示的为从I路径所接收到的信号与Q路径所接收到的信号之间的增益差，而θ则为I路径所接收到的信号与Q路径所接收到的信号之间的相位差。-k则用以表示与第k个子载波处于镜像位置的子载波。例如，子载波的总数为16，而第k个子载波为第1个子载波时，第-k个子载波即为第16个子载波。where g represents the gain difference between the signal received from the I path and the signal received from the Q path, and θ is the gain difference between the signal received from the I path and the signal received from the Q path Phase difference. -k is used to indicate the subcarrier that is in the image position of the kth subcarrier. For example, the total number of subcarriers is 16, and when the kth subcarrier is the first subcarrier, the -kth subcarrier is the 16th subcarrier.
由上述式（2）所示，式（2）中第一项的Z(k)即为本案中欲接收的理想数据内容，而第二项的βZ*(-k)，则为接收信号R(k)中的镜像干扰（来自第k个子载波镜像位置的第-k个子载波的干扰）。因此，为了估测并补偿上述的镜像干扰，便需将上述的干扰Z*(-k)消除，或是降至最低。As shown in the above formula (2), Z(k) of the first term in formula (2) is the ideal data content to be received in this case, and βZ*(-k) of the second term is the received signal R Image interference in (k) (interference from the -kth subcarrier at the mirror position of the kth subcarrier). Therefore, in order to estimate and compensate the above-mentioned image interference, it is necessary to eliminate or minimize the above-mentioned interference Z*(-k).
在此，则定义均衡参数D，可被表示为：Here, the equalization parameter D is defined, which can be expressed as:
即为，上述式（2）信号R(k)前后项的系数比例，当得到均衡参数D之值时，利用补偿器220便可进一步利用均衡参数D对信号R(k)进行补偿。经推导后，上述的式（3）更可以被表示为：That is, the ratio of coefficients between the front and rear terms of the signal R(k) in the above formula (2), when the value of the equalization parameter D is obtained, the compensator 220 can further use the equalization parameter D to compensate the signal R(k). After derivation, the above formula (3) can be expressed as:
其中，r1(k)为第一目标符号，r2(k)则为第二目标符号，而r1(-k)为第一镜像符号，r2(-k)则为第二镜像符号，上述的符号皆为信号R(k)中的符号，在此为已知的数据。而x1(k)、x2(k)则分别代表第一目标符号以及第二目标符号的理想值，即第一目标符号以及第二目标符号在传送端传送时的数据内容，在此则为未知值。以下则以式（4）为基础，说明目标符号以及镜像符号的关系以及如何利用上述式（4）求得均衡参数D。Among them, r1 (k) is the first target symbol, r2 (k) is the second target symbol, r1 (-k) is the first mirror image symbol, r2 (-k) is the second mirror image symbol , the above-mentioned symbols are all symbols in the signal R(k), which are known data here. And x1 (k), x2 (k) respectively represent the ideal values of the first target symbol and the second target symbol, that is, the data content of the first target symbol and the second target symbol when they are transmitted at the transmitting end, here is an unknown value. The following is based on formula (4) to illustrate the relationship between the target symbol and the mirror image symbol and how to use the above formula (4) to obtain the equalization parameter D.
图3A、图3B及图3C为根据本发明一实施例所示出目标符号以及镜像符号对应于通信资源（communication resource）的关系示意图。在图3A、图3B及图3C中，通信资源30～32对应于上述的接收信号R(k)，而图3A、图3B及图3C中，横轴对应于时间，纵轴则对应于接收信号R(k)的k个子载波。而通信资源30～32上的方格则对应于接收信号R(k)的于各个时间点、各个子载波上的资源元素（resource element），而资源元素上则可承载一个符号。其中，在本发明中，第一目标符号OS1可为通信资源30（或通信资源31、32）中的任一资源元素承载的符号。FIG. 3A , FIG. 3B and FIG. 3C are schematic diagrams illustrating the relationship between target symbols and image symbols corresponding to communication resources according to an embodiment of the present invention. In FIG. 3A, FIG. 3B and FIG. 3C, communication resources 30-32 correspond to the above-mentioned received signal R(k), while in FIG. 3A, FIG. 3B and FIG. 3C, the horizontal axis corresponds to time, and the vertical axis corresponds to the received signal k subcarriers of signal R(k). The squares on the communication resources 30 - 32 correspond to resource elements (resource elements) on each subcarrier at each time point of the received signal R(k), and a resource element can carry a symbol. Wherein, in the present invention, the first object symbol OS1 may be a symbol carried by any resource element in the communication resource 30 (or the communication resource 31, 32).
而如图3A～3C所示，第一镜像符号MS1即为与第一目标符号OS1处于同一时间点，但位于镜像位置上的资源元素所承载的符号。第二目标符号OS2为另一时间点，位于同样与第一目标符号OS1位于相同的子载波之资源元素上。同理，第二镜像符号MS2即与第二目标符号OS2处于同一时间点，但位于镜像位置上的资源元素所承载的符号。因此，第一镜像符号MS1及第二镜像符号MS2亦会对应于相同的子载波。其中，第一目标符号OS1以及第二目标符号OS2可如图3A、图3B所示，处于相邻的时间点，亦可如图3C一般，在其分别对应的两个时间点之间具有一定的时间点间隔而不相邻，本发明并不限定于上述。As shown in FIGS. 3A to 3C , the first mirror image symbol MS1 is a symbol carried by a resource element at the same time point as the first object symbol OS1 but at a mirror image position. The second target symbol OS2 is another point in time, and is located on a resource element that is also located on the same subcarrier as the first target symbol OS1. Similarly, the second mirror image symbol MS2 is a symbol carried by a resource element at the same time point as the second target symbol OS2 but located at the mirror image position. Therefore, the first mirror symbol MS1 and the second mirror symbol MS2 also correspond to the same subcarrier. Wherein, the first object symbol OS1 and the second object symbol OS2 may be at adjacent time points as shown in FIG. 3A and FIG. 3B , or as shown in FIG. The time points are not adjacent to each other, and the present invention is not limited to the above.
设定目标符号OS1～OS2以及镜像符号MS1～MS2（例如，如图3A所示之位置）后，通过将x1(k)、x2(k)所有的可能值带入式（4）中，便可得到多个候选均衡参数d。例如，当信号R(k)是以正交振幅调制（Quadrature Amplitude Modulation,QAM）之中的16-QAM作为调制机制调制各符号时，每个符号皆具有16种的可能，综合x1(k)、x2(k)皆有16种的可能，在此便可产生256个候选均衡参数d。这256个候选均衡参数便集合为一均衡参数组Dn，可表示为：After setting the target symbols OS1～OS2 and mirror symbols MS1～MS2 (for example, the positions shown in Figure 3A), by bringing all possible values of x1 (k) and x2 (k) into formula (4) , multiple candidate equalization parameters d can be obtained. For example, when the signal R(k) uses 16-QAM in Quadrature Amplitude Modulation (QAM) as the modulation mechanism to modulate each symbol, each symbol has 16 possibilities, and the comprehensive x1 (k ), x2 (k) have 16 possibilities, and 256 candidate equalization parameters d can be generated here. These 256 candidate equalization parameters are assembled into an equalization parameter group Dn , which can be expressed as:
Dn=[xn,1,xn,2,xn,3,...,xn,256] （5）Dn =[xn,1 ,xn,2 ,xn,3 ,...,xn,256 ] (5)
而分别通过设定目标符号OS1～OS2以及镜像符号MS1～MS2于不同的位置，例如图3A～3C所示的位置，便可得到n组的均衡参数组，而n的预设值则根据实施时的实际状况而设定，本发明并不限定。By setting the target symbols OS1-OS2 and mirror images MS1-MS2 at different positions, such as the positions shown in Figures 3A-3C, n groups of equalization parameter groups can be obtained, and the preset value of n depends on the implementation It is set according to the actual situation at the time, and the present invention is not limited.
接着，则必须从上述的均衡参数组Dn中找出正确的均衡参数D。一种较为直观的方法为，对上述的均衡参数组Dn进行交集，当交集结果为唯一（即交集的结果集合中的元素（element）数量为1）时，则可确定该唯一解即为均衡参数D。然而，获取到的第一目标符号及第二目标符号的理想值相同时（即x1(k)与x2(k)相同，而x1(k)与x2(k)的比值为1），则会造成并集结果为空集合，无法得到期望的结果。Next, it is necessary to find out the correct equalization parameter D from the above equalization parameter groupDn . A more intuitive method is to intersect the above equalization parameter group Dn , and when the result of the intersection is unique (that is, the number of elements in the result set of the intersection is 1), it can be determined that the unique solution is Balance parameter D. However, when the obtained ideal values of the first target symbol and the second target symbol are the same (that is, x1 (k) and x2 (k) are the same, and the ratio of x1 (k) to x2 (k) is 1 ), it will cause the result of the union to be an empty set, and the desired result cannot be obtained.
于是，在本发明一实施例中，则采用另一种方式避开上述的问题。即，首先先选取部分或全部的均衡参数组Dn进行并集得到均衡参数集，再用同样的作法选取不同的均衡参数组Dn产生指定数量的均衡参数集，即M个均衡参数集UM。再接着利用上述的M个均衡参数集取交集，而得到均衡参数D。例如，在上述步骤中产生14组均衡参数组（即n=14），并且利用这些均衡参数组产生3个均衡参数集（即M=3）。以下则为均衡参数集的一种实施方式：Therefore, in an embodiment of the present invention, another method is adopted to avoid the above-mentioned problems. That is, first select part or all of the equalization parameter groupsDn and combine them to obtain an equalization parameter set, and then use the same method to select different equalization parameter groupsDn to generate a specified number of equalization parameter sets, that is, M equalization parameter sets UM. Then, the above-mentioned M equalization parameter sets are used to obtain the intersection, and the equalization parameter D is obtained. For example, 14 equalization parameter sets (ie, n=14) are generated in the above steps, and three equalization parameter sets (ie, M=3) are generated by using these equalization parameter sets. The following is an implementation manner of the equalization parameter set:
U1=D1∪D2∪D3∪D4∪D5U1 =D1 ∪D2 ∪D3 ∪D4 ∪D5
U2=D6∪D7∪D8∪D9∪D10U2 =D6 ∪D7 ∪D8 ∪D9 ∪D10
U3=D11∪D12∪D13∪D14 （6）U3 =D11 ∪D12 ∪D13 ∪D14 (6)
则，均衡参数D即为：Then, the equalization parameter D is:
D=U1∩U2∩U3 （7）D=U1 ∩ U2 ∩ U3 (7)
值得一提的是，均衡参数集中的均衡参数组不一定需要如同式（6）所示的内容。选取的均衡参数组可与其他的均衡参数集所选取的均衡参数组重复，亦不一定需依照特定顺序或规则。当式（7）的结果集合中的元素数量为1时，则判断该元素为均衡参数D。若是结果集合中的元素数量大于1，或是为空集合时，则表示结果未收敛，可利用增加均衡参数集或是均衡参数组并重新交集产生结果集合。下述的实施例则将针对此部分进行更详细的说明。It is worth mentioning that the equalization parameter group in the equalization parameter set does not necessarily need to be as shown in equation (6). The selected equalization parameter set may be repeated with the equalization parameter set selected by other equalization parameter sets, and does not necessarily follow a specific order or rule. When the number of elements in the result set of formula (7) is 1, it is judged that the element is equalization parameter D. If the number of elements in the result set is greater than 1, or it is an empty set, it means that the result has not converged, and the result set can be generated by adding an equalization parameter set or equalization parameter group and re-intersecting. The following embodiments will describe this part in more detail.
根据上式（7）得到均衡参数D后，即可将均衡参数D传送至补偿器，根据均衡参数D对频域信号R（即R(k)）进行补偿。而频域信号R中的理想的数据内容Z(k)则可被表示为：After the equalization parameter D is obtained according to the above formula (7), the equalization parameter D can be transmitted to the compensator, and the frequency domain signal R (that is, R(k)) can be compensated according to the equalization parameter D. The ideal data content Z(k) in the frequency domain signal R can be expressed as:
其中G=α(1-DD*) （8） where G=α(1-DD*) (8)
将均衡参数D带入上式（8）后，便可得到频域信号R中的理想数据内容Z(k)。本发明中的估测补偿方法及装置便可依照上述的式（1）～式（8）所示的处理方式估测所接收的频域信号并补偿所述的频域信号。After the equalization parameter D is brought into the above formula (8), the ideal data content Z(k) in the frequency domain signal R can be obtained. The estimation and compensation method and device in the present invention can estimate the received frequency domain signal and compensate the frequency domain signal according to the processing methods shown in the above formula (1) to formula (8).
图4为根据本发明一实施例所示出估测补偿方法的流程步骤图。相较于图1，图4所示实施例提供了一种于步骤S101～S102较为详细的实施方式，其中，S401～S404对应于图1所示的步骤S101，而S405～S412则对应至图1中的步骤S102。请参照图2及图4，首先，在步骤S401时，估测器210接收频域信号R，其中频域信号R在多个时间点具有多个符号。然后在步骤S402及S403时，估测器210分别从频域信号R中获取第一目标符号及第二目标符号，及各自对应的第一镜像符号及第二镜像符号。FIG. 4 is a flowchart showing the steps of an estimation and compensation method according to an embodiment of the present invention. Compared with FIG. 1, the embodiment shown in FIG. 4 provides a more detailed implementation of steps S101-S102, wherein S401-S404 corresponds to step S101 shown in FIG. 1, and S405-S412 corresponds to Step S102 in 1. Please refer to FIG. 2 and FIG. 4 , firstly, in step S401 , the estimator 210 receives a frequency-domain signal R, wherein the frequency-domain signal R has multiple symbols at multiple time points. Then in steps S402 and S403 , the estimator 210 obtains the first target symbol and the second target symbol, and the corresponding first image symbol and the second image symbol respectively from the frequency domain signal R.
接着，在步骤S404时，估测器210可利用上述式（4）、（5）及相关叙述的方式产生多个均衡参数组。并且在步骤S405时，判断产生的均衡参数组的数量（即上述之n值）是否已达预设值。若否，则重复执行S402～S404来产生均衡参数组，直到均衡参数组的数量到达预设值。若是，则接续执行步骤S406。Next, in step S404 , the estimator 210 can generate a plurality of equalization parameter sets by using the above formulas (4), (5) and related descriptions. And in step S405, it is determined whether the number of equalization parameter sets generated (that is, the above-mentioned n value) has reached a preset value. If not, repeatedly execute S402-S404 to generate equalization parameter sets until the number of equalization parameter sets reaches a preset value. If yes, proceed to step S406.
在步骤S406时，估测器210则选取部分或全部的均衡参数组并并集选取的均衡参数组，产生均衡参数集（例如，以如同式（7）所示方式产生）。并且，重复的选取不同部分或全部的均衡参数组并并集上述选取的均衡参数组，直到产生到达预定数量的均衡参数集。接着，在步骤S407时，将于步骤S406所产生、预定数量的均衡参数集进行交集，产生结果集合。接着于步骤S408时，判断结果集合中的元素数量是否为1。当结果集合中的元素数量为1时，则估测器210判断此元素为均衡参数D，并将均衡参数D传送至补偿器220，使得补偿器220可根据均衡参数D进行补偿。In step S406 , the estimator 210 selects part or all of the equalization parameter sets and combines the selected equalization parameter sets to generate an equalization parameter set (for example, in the manner shown in equation (7)). In addition, different parts or all of the equalization parameter sets are repeatedly selected and the above-mentioned selected equalization parameter sets are combined until a predetermined number of equalization parameter sets are generated. Next, in step S407, a predetermined number of equalization parameter sets generated in step S406 are intersected to generate a result set. Then in step S408, it is determined whether the number of elements in the result set is 1. When the number of elements in the result set is 1, the estimator 210 determines that the element is the equalization parameter D, and transmits the equalization parameter D to the compensator 220 so that the compensator 220 can perform compensation according to the equalization parameter D.
然而，当在步骤S408时判断结果集合中的元素数量不为1时，估测器210则根据模式的设定不同而以不同的流程重新产生结果集合。当估测器210被设定为模式1（步骤S410，模式为1）时，估测器210增加均衡参数集的指定数量（步骤S411），便可于步骤S406时，产生更多的均衡参数集（延伸均衡参数集），再接着利用这些均衡参数集（原有的均衡参数集以及延伸均衡参数集）交集得到结果集合（步骤S407）。在本发明一实施例中，估测器210增加均衡参数集的指定数量的同时，还调整原有的均衡参数集中所包括的均衡参数组，但本发明并不限定于上述。However, when it is determined in step S408 that the number of elements in the result set is not 1, the estimator 210 regenerates the result set with different processes according to different mode settings. When the estimator 210 is set to mode 1 (step S410, mode is 1), the estimator 210 increases the specified number of equalization parameter sets (step S411), so that more equalization parameters can be generated in step S406 set (extended equalization parameter set), and then use the intersection of these equalization parameter sets (the original equalization parameter set and the extended equalization parameter set) to obtain a result set (step S407). In one embodiment of the present invention, the estimator 210 adjusts the equalization parameter sets included in the original equalization parameter set while increasing the specified number of equalization parameter sets, but the present invention is not limited to the above.
而当估测器210被设定为模式2（步骤S410，模式为2）时，估测器210增加均衡参数组的预设值（步骤S412），亦即，估测器210必须重复步骤S402至步骤S405，增加获取的目标符号及镜像符号，已得到更多的均衡参数组（延伸均衡参数组）。于步骤S406时，估测器210则可运用原有的均衡参数组以及上述增加的均衡参数组（延伸均衡参数组）产生更多的均衡参数集，再接着利用这些均衡参数集交集得到结果集合（步骤S407）。And when the estimator 210 is set to mode 2 (step S410, mode is 2), the estimator 210 increases the preset value of the equalization parameter set (step S412), that is, the estimator 210 must repeat step S402 Going to step S405, adding the obtained target symbol and mirror image symbol to obtain more equalization parameter sets (extended equalization parameter sets). In step S406, the estimator 210 can use the original equalization parameter set and the above-mentioned added equalization parameter set (extended equalization parameter set) to generate more equalization parameter sets, and then use the intersection of these equalization parameter sets to obtain a result set (step S407).
在本发明一实施例中，一均衡参数组中的目标符号及镜像符号（第一目标符号及第一镜像符号，或第二目标符号及第二镜像符号）可与另一均衡参数组中的一组目标符号及镜像符号相同，以降低产生均衡参数组的复杂度。但两组均衡参数组中不能包括完全相同的两组目标符号及镜像符号（两组中之一组为第一目标符号及第一镜像符号，以及另一组为第二目标符号及第二镜像符号）。In an embodiment of the present invention, the target symbol and the mirror image symbol (the first target symbol and the first mirror image symbol, or the second target symbol and the second mirror image symbol) in one equalization parameter set can be compared with the other equalization parameter set A set of target symbols and mirror images are identical to reduce the complexity of generating equalization parameter sets. However, the two sets of equalization parameter groups cannot include exactly the same two sets of target symbols and mirror images (one of the two groups is the first target symbol and the first mirror image, and the other group is the second target symbol and the second mirror image) symbol).
而估测器210的模式（对应于步骤S410）的设定则可以手动方式预先设定于估测器210中，亦可根据实际状况调整选择的模式。例如，预设模式为1，当于模式1执行超过一指定时间值，或是指定数量超过一限制值时，估测器210则主动将模式切换至模式2，但本发明并不限定于上述的实施方式。The setting of the mode of the estimator 210 (corresponding to step S410 ) can be preset in the estimator 210 manually, and the selected mode can also be adjusted according to the actual situation. For example, the default mode is 1. When the execution of mode 1 exceeds a specified time value, or the specified quantity exceeds a limit value, the estimator 210 will actively switch the mode to mode 2, but the present invention is not limited to the above implementation.
以下则针对本发明所提出的估测补偿装置及其方法运用于实际的OFDM通信系统中的接收端进行说明。图5为根据本发明一实施例所示出接收端的功能方块图，其中图5所示接收端50包括本发明所提出的估测补偿装置20。请参照图5，接收端50包括前端电路510、快速傅立叶转换单元520、估测补偿装置20、均衡器530以及解调器540。其中，前端电路510包括天线单元511、本地振荡器512、混波器513～514、低通滤波器（Low Pass Filter,LPF）515～516以及模拟/数字转换器（Analog-to-Digital Converter,ADC）517～518。The following will describe the application of the estimation and compensation device and method proposed by the present invention to the receiving end in an actual OFDM communication system. FIG. 5 is a functional block diagram of a receiving end according to an embodiment of the present invention, wherein the receiving end 50 shown in FIG. 5 includes the estimation and compensation device 20 proposed by the present invention. Referring to FIG. 5 , the receiver 50 includes a front-end circuit 510 , a fast Fourier transform unit 520 , an estimation and compensation device 20 , an equalizer 530 and a demodulator 540 . Wherein, the front-end circuit 510 includes an antenna unit 511, a local oscillator 512, mixers 513-514, low-pass filters (Low Pass Filter, LPF) 515-516, and an analog-to-digital converter (Analog-to-Digital Converter, ADC) 517-518.
天线单元511可包括单一天线或多天线。混波器513将从天线单元511接收OFDM通信系统中的模拟时域信号Z，与本地振荡器512所提供的余弦波（图5所示cosωct），混波而得到I路径的模拟时域信号ZI。模拟时域信号ZI再接着经过LPF515以及ADC517的处理后成为I路径的数字时域信号ZID。The antenna unit 511 may include a single antenna or multiple antennas. The mixer 513 mixes the analog time-domain signal Z in the OFDM communication system received from the antenna unit 511 with the cosine wave (cosωc t shown in FIG. 5 ) provided by the local oscillator 512 to obtain the analog time domain of the I path domain signal ZI. The analog time-domain signal ZI is then processed by the LPF515 and the ADC517 to become the digital time-domain signal ZID of the I path.
另一方面，混波器513将从天线单元511接收OFDM通信系统中的模拟时域信号Z，与本地振荡器512所提供的正弦波（图5所示-gsin(ωct+θ)），混波而得到Q路径的模拟时域信号ZQ。模拟时域信号ZQ再接着经过LPF516以及ADC518的处理后成为Q路径的数字时域信号ZQD。上述的正弦波中的θ为本地振荡器512于产生正弦波时所产生，与供给至混波器513的余弦波之间的相位差，g则为本地振荡器512于产生正弦波时所产生，与供给至混波器513的余弦波之间的增益差。上述的相位差θ及增益差g即对应于式（2）中的增益差g及相位差θ，为影响IQ路径不均衡的最大因素。On the other hand, the mixer 513 will receive the analog time-domain signal Z in the OFDM communication system from the antenna unit 511, and the sine wave provided by the local oscillator 512 (-gsin(ωc t+θ) shown in FIG. 5 ) , to get the analog time-domain signal ZQ of the Q path by mixing. The analog time-domain signal ZQ is then processed by the LPF516 and the ADC518 to become the digital time-domain signal ZQD of the Q path. θ in the above-mentioned sine wave is the phase difference between the cosine wave supplied to the mixer 513 and the phase difference generated by the local oscillator 512 when generating the sine wave, and g is the phase difference generated by the local oscillator 512 when generating the sine wave , and the gain difference between the cosine wave supplied to the mixer 513 . The above-mentioned phase difference θ and gain difference g correspond to the gain difference g and phase difference θ in formula (2), and are the biggest factors affecting the imbalance of the IQ path.
快速傅立叶转换单元520接收并转换I路径的数字时域信号ZID路径的数字时域信号ZQD成频域信号R，并传送频域信号R至估测补偿装置20。估测补偿装置20则可通过上述实施例所述内容的方式对频域信号R中的IQ不均衡效应进行补偿，而产生补偿后频域信号R'。补偿后频域信号R'再接着经过均衡器530以及解调器540的处理，便可转换为接收端50所欲接收的数据DAT。The FFT unit 520 receives and converts the digital time domain signal ZQD of the I path ZQD into a frequency domain signal R, and transmits the frequency domain signal R to the estimation and compensation device 20 . The estimation and compensation device 20 can compensate the IQ imbalance effect in the frequency-domain signal R through the methods described in the above-mentioned embodiments to generate a compensated frequency-domain signal R′. After the compensation, the frequency domain signal R′ is then processed by the equalizer 530 and the demodulator 540 to be converted into the data DAT to be received by the receiving end 50 .
综上所述，本发明提供了一种估测补偿方法及估测补偿装置，利用盲估测（blindestimation）的方式，获取频域信号中对称位置的未知的数据信号（即目标符号及镜像符号）来估测IQ不均衡效应。并通过上述的估测产生均衡参数，并利用所述的均衡参数对频域信号进行补偿。通过本发明所提出的估测补偿方法及估测补偿装置，则不需要预先在传送信号中额外增加任何前置信号或引导信号，维持了一定的数据传输率。同时，相较于现有使用盲估测方式的补偿方式，以本发明所提出的估测补偿方法及估测补偿装置得到均衡参数的收敛时间亦较短，藉此降低了计算复杂度以及接收端接收信号的延迟时间（latencytime）。To sum up, the present invention provides an estimation and compensation method and estimation and compensation device, which use blind estimation to obtain unknown data signals (i.e., target symbols and image symbols) at symmetrical positions in the frequency domain signal. ) to estimate the IQ imbalance effect. And the equalization parameter is generated through the above estimation, and the frequency domain signal is compensated by using the equalization parameter. With the estimation and compensation method and estimation and compensation device proposed by the present invention, there is no need to add any preamble or pilot signal to the transmission signal in advance, and a certain data transmission rate is maintained. At the same time, compared with the existing compensation method using blind estimation method, the convergence time of the equalization parameters obtained by the estimation compensation method and estimation compensation device proposed by the present invention is also shorter, thereby reducing the computational complexity and receiving The delay time (latencytime) of receiving the signal at the terminal.
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本发明各实施例技术方案的范围。Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.
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