CN102820935B

CN102820935B - The detection method of Alamouti code in a kind of MIMO-OFDM system

Info

Publication number: CN102820935B
Application number: CN201110151788.2A
Authority: CN
Inventors: 朱磊; 熊勇; 杨秀梅; 贾国庆; 雷舒培; 易正琨
Original assignee: Shanghai Research Center for Wireless Communications
Current assignee: Shanghai Research Center for Wireless Communications
Priority date: 2011-06-08
Filing date: 2011-06-08
Publication date: 2015-09-16
Anticipated expiration: 2031-06-08
Also published as: CN102820935A

Abstract

The invention discloses a method for detecting Alamouti codes in a MIMO-OFDM system. In the method, the transmitting end is equipped with two antennas, and the receiving end is equipped with Nr antennas. The received signals in the two intervals are respectively expressed as: and Among them, G ₀ =0, G _j represents the RF link gain of receiving antenna j (j=0,1,…,Nr-1) relative to receiving antenna 0, and the noise variance of receiving antenna i is respectively and satisfied The detection signal is expressed as: The weighting factor w _j is: w _j =(G _j a _j ) ^-1 , j=0,1,...,Nr-1. The detection method of the Alamouti code in the MIMO-OFDM system according to the present invention takes into account the serious impact of the noise and gain imbalance between the receiving antennas on signal detection, and it has obtained a larger performance gain than the detection method of the traditional Alamouti code , which improves the detection performance.

Description

A Detection Method of Alamouti Code in MIMO-OFDM System

技术领域technical field

本发明属于通信技术领域，涉及一种考虑了接收天线之间噪声和增益不平衡的MIMO-OFDM系统中Alamouti码的检测方法。The invention belongs to the technical field of communication, and relates to a method for detecting Alamouti codes in an MIMO-OFDM system in consideration of noise and gain imbalance between receiving antennas.

背景技术Background technique

随着高数据速率通信的需求以及频谱资源的稀缺性，研究和工程领域中提出了多输入多输出(Multiple Inputs Multiple Outputs，MIMO)技术，有效地提高了通信系统的容量以及数据传输的可靠性。在MIMO系统中发射端和接收端都配备了多根天线。空时编码(SpaceTime Coding)是一种可以取得空间分集和编码增益的主要技术。研究中发现的最重要也是最实用的空时编码技术就是Alamouti码，因为其编码和解码简单，同时可以在两根发射天线时取得完全的分集增益。另外Alamouti码也可以在频域上进行编码，相应的编码称为空频编码(Space Frequency Coding)。正是因为Alamouti码的良好的编码特性及其在应用上的灵活性，其成了研究中的热点技术。With the demand for high data rate communication and the scarcity of spectrum resources, multiple input multiple output (Multiple Inputs Multiple Outputs, MIMO) technology has been proposed in the field of research and engineering, which effectively improves the capacity of the communication system and the reliability of data transmission. . In the MIMO system, both the transmitting end and the receiving end are equipped with multiple antennas. Space-time coding (SpaceTime Coding) is a main technology that can achieve space diversity and coding gain. The most important and practical space-time coding technique found in the research is the Alamouti code, because it is simple to encode and decode, and can achieve full diversity gain with two transmit antennas. In addition, the Alamouti code can also be coded in the frequency domain, and the corresponding code is called Space Frequency Coding (Space Frequency Coding). It is precisely because of the good coding characteristics of Alamouti code and its flexibility in application that it has become a hot technology in research.

同时，正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术是另外一种在信道上传输信号的关键技术。OFDM把宽带的多径衰落信道转化成一系列并行的窄带的平坦衰落信道。OFDM技术和MIMO技术的结合是直观而且自然的，因为MIMO技术可以在每一个OFDM子载波上应用(MIMO-OFDM)。最新的通信系统如IEEE WiMAX、3GPP LTE(LTE-A)等已经把MIMO-OFDM技术列入技术标准中。At the same time, Orthogonal Frequency Division Multiplexing (OFDM) technology is another key technology for transmitting signals on channels. OFDM converts wideband multipath fading channels into a series of parallel narrowband flat fading channels. The combination of OFDM technology and MIMO technology is intuitive and natural, because MIMO technology can be applied on every OFDM subcarrier (MIMO-OFDM). The latest communication systems such as IEEE WiMAX and 3GPP LTE (LTE-A) have included MIMO-OFDM technology in technical standards.

在现有的研究中，接收天线之间的噪声和增益都是假设相等的。但是，像LTE等实际系统中，每个接收天线都使用不同的射频链路，如果不同射频链路的射频模块的规格不同，射频链路产生的噪声是不同的；而且不同的天线之间受到的外界干扰程度可能也是不同的，这就造成了接收天线之间的噪声不平衡。另外，实际系统中每根接收天线使用独立的AGC模块来控制输入到AGC模块的信号幅度，由于接收天线和发射天线之间的无线信道是独立随机衰落的，因此，接收天线之间的增益也是不平衡的。以往的文献中在研究Alamouti码时都是假设接收天线之间的噪声和增益是相等的，这种假设在很大程度上简化了问题，产生了很多有意义的成果，但是如果噪声和增益不平衡的问题没有得到很好的处理，将使得检测性能严重的下降。In the existing research, the noise and gain between the receiving antennas are assumed to be equal. However, in practical systems such as LTE, each receiving antenna uses a different RF link. If the specifications of the RF modules of different RF links are different, the noise generated by the RF link will be different; and different antennas are affected by The degree of external interference may also be different, which creates a noise imbalance between the receiving antennas. In addition, each receiving antenna in the actual system uses an independent AGC module to control the signal amplitude input to the AGC module. Since the wireless channel between the receiving antenna and the transmitting antenna is independently and randomly fading, the gain between the receiving antennas is also unbalanced. In the previous literature, when studying Alamouti codes, it was assumed that the noise and gain between the receiving antennas were equal. This assumption greatly simplifies the problem and produced many meaningful results. However, if the noise and gain are not If the balance problem is not handled well, the detection performance will be severely degraded.

发明内容Contents of the invention

本发明所要解决的技术问题是：提供一种MIMO-OFDM系统中Alamouti码的检测方法，该方法考虑到了接收天线之间噪声和增益的不平衡对信号检测的严重影响，提高了信号检测的性能。The technical problem to be solved by the present invention is to provide a method for detecting Alamouti codes in a MIMO-OFDM system, which takes into account the serious impact of noise and gain imbalance between receiving antennas on signal detection, and improves the performance of signal detection .

为解决上述技术问题，本发明采用如下技术方案。In order to solve the above technical problems, the present invention adopts the following technical solutions.

一种MIMO-OFDM系统中Alamouti码的检测方法，发送端配备2的倍数根天线，接收端配备有Nr根天线，两个间隔内的接收信号分别表示为：A method for detecting Alamouti codes in a MIMO-OFDM system. The transmitting end is equipped with multiple antennas of 2, and the receiving end is equipped with Nr antennas. The received signals in the two intervals are respectively expressed as:

$[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \end{matrix}] = [\begin{matrix} G_{0} H_{00}^{0} & G_{0} H_{01}^{0} \\ G_{1} H_{10}^{0} & G_{1} H_{11}^{0} \\ . & . \\ . & . \\ . & . \\ G_{Nr - 1} H_{Nr - 1,0}^{0} & G_{Nr - 1} H_{Nr - 1,1}^{0} \end{matrix}] [\begin{matrix} s_{0} \\ s_{1} \end{matrix}] + [\begin{matrix} G_{0} n_{0}^{(0)} \\ G_{1} n_{0}^{(1)} \\ . \\ . \\ . \\ G_{Nr - 1} n_{0}^{(1)} \end{matrix}]$ 和 $[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \end{matrix}] = [\begin{matrix} G_{0} h_{00}^{0} & G_{0} h_{01}^{0} \\ G_{1} h_{10}^{0} & G_{1} h_{11}^{0} \\ . & . \\ . & . \\ . & . \\ G_{Nr - 1} h_{Nr - 1,0}^{0} & G_{Nr - 1} h_{Nr - 1,1}^{0} \end{matrix}] [\begin{matrix} {the s}_{0} \\ {the s}_{1} \end{matrix}] + [\begin{matrix} G_{0} {no}_{0}^{(0)} \\ G_{1} {no}_{0}^{(1)} \\ . \\ . \\ . \\ G_{Nr - 1} {no}_{0}^{(1)} \end{matrix}]$ and

$[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \end{matrix}] = = [\begin{matrix} {G G}_{00} {H h}_{0000}^{11} & {G G}_{00} {H h}_{0101}^{11} \\ {G G}_{11} {H h}_{1010}^{11} & {G G}_{11} {H h}_{1111}^{11} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,0 1,0}^{11} & {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,1 1,1}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {G G}_{00} {n no}_{11}^{((00))} \\ {G G}_{11} {n no}_{11}^{((11))} \\ . . \\ . . \\ . . \\ {G G}_{Nr Nr - - 11} {n no}_{11}^{((11))} \end{matrix}],,$

其中G_j表示接收天线j(j＝0,1,…,Nr-1)相对于接收天线0的射频链路增益，*为复共轭符号，表示接收天线j上在间隔i内的接收信号，表示发射天线k和接收天线m之间的信道响应的独立随机变量，表示在间隔i内接收天线j上的零均值的加性高斯噪声，的方差为i＝0,1,…,Nr-1且s_k表示Alamouti编码之前的发送信号，s_k的下标k表示第k个信号；where G _j represents the RF link gain of receiving antenna j (j=0,1,…,Nr-1) relative to receiving antenna 0, * is the complex conjugate symbol, Denotes the received signal on receiving antenna j in interval i, An independent random variable representing the channel response between transmit antenna k and receive antenna m, represents zero-mean additive Gaussian noise over receive antenna j in interval i, The variance of i=0,1,...,Nr-1 and s _k represents the transmitted signal before Alamouti encoding, and the subscript k of s _k represents the kth signal;

定义变量a₀＝1，G₀＝1，检测信号表示为：Define variable a ₀ =1, G ₀ =1, and the detection signal is expressed as:

$\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {Σ Σ}_{i i = = 00}^{Nr Nr - - 11} (({H h}_{i i 00}^{00 * *} {r r}_{i i}^{00} + + {H h}_{i i 11}^{11} {r r}_{i i}^{11 * *})) \\ {\overset{~ ~}{s the s}}_{11} = = {Σ Σ}_{i i = = 00}^{Nr Nr - - 11} (({H h}_{i i 11}^{00 * *} {r r}_{i i}^{00} - - {H h}_{i i 00}^{11} {r r}_{i i}^{11 * *})) \end{matrix}$

其中加权因子w为：w_i＝(G_ia_i)^-1,i＝0,1，…,Nr-1。Wherein the weighting factor w is: w _i =(G _i a _i ) ⁻¹ , i=0, 1, . . . , Nr-1.

作为本发明的一种优选方案，Nr＝2，发送端和接收端都配备有2根天线，两个间隔内的接收信号分别表示为：As a preferred solution of the present invention, Nr=2, the transmitting end and the receiving end are equipped with 2 antennas, and the received signals in the two intervals are respectively expressed as:

$[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \end{matrix}] = [\begin{matrix} H_{00}^{0} & H_{01}^{0} \\ G H_{10}^{0} & {GH}_{11}^{0} \end{matrix}] [\begin{matrix} s_{0} \\ s_{1} \end{matrix}] + [\begin{matrix} n_{0}^{(0)} \\ n_{0}^{(1)} \end{matrix}]$ 和 $[\begin{matrix} r_{1}^{(0)} \\ r_{1}^{(1)} \end{matrix}] = [\begin{matrix} H_{00}^{1} & H_{01}^{1} \\ G H_{10}^{1} & {GH}_{11}^{1} \end{matrix}] [\begin{matrix} - s_{1}^{*} \\ s_{0}^{*} \end{matrix}] + [\begin{matrix} n_{1}^{(0)} \\ n_{1}^{(1)} \end{matrix}],$ $[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \end{matrix}] = [\begin{matrix} h_{00}^{0} & h_{01}^{0} \\ G h_{10}^{0} & {GH}_{11}^{0} \end{matrix}] [\begin{matrix} {the s}_{0} \\ {the s}_{1} \end{matrix}] + [\begin{matrix} {no}_{0}^{(0)} \\ {no}_{0}^{(1)} \end{matrix}]$ and $[\begin{matrix} r_{1}^{(0)} \\ r_{1}^{(1)} \end{matrix}] = [\begin{matrix} h_{00}^{1} & h_{01}^{1} \\ G h_{10}^{1} & {GH}_{11}^{1} \end{matrix}] [\begin{matrix} - {the s}_{1}^{*} \\ {the s}_{0}^{*} \end{matrix}] + [\begin{matrix} {no}_{1}^{(0)} \\ {no}_{1}^{(1)} \end{matrix}],$

其中，G表示接收天线1相对于接收天线0的增益，接收天线0和接收天线1的噪声方差分别为和且满足检测信号表示为：Among them, G represents the gain of receiving antenna 1 relative to receiving antenna 0, and the noise variances of receiving antenna 0 and receiving antenna 1 are respectively and and satisfied The detection signal is expressed as:

$\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {H h}_{0000}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1010}^{00 * *} {r r}_{00}^{((11))} + + {H h}_{0101}^{11} {r r}_{11}^{((00)) * *} + + w w {GH GH}_{1111}^{11} {r r}_{11}^{((11)) * *} \\ {\overset{~ ~}{s the s}}_{11} = = {H h}_{0101}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1111}^{00 * *} {r r}_{00}^{((11))} - - {H h}_{0000}^{11} {r r}_{11}^{((00)) * *} - - w w {GH GH}_{1010}^{11} {r r}_{11}^{((11)) * *} \end{matrix}$

加权因子w为：w_i＝(G_ia_i)^-1,i＝0,1。The weighting factor w is: w _i =(G _i a _i ) ^-1 , i=0,1.

作为本发明的另一种优选方案，在MIMO-OFDM系统中，天线上相邻的两个子载波频率分别为f₀和f₁，相应的频率响应为H⁰和H¹，子载波f₀和f₁上的接收信号分别为：As another preferred solution of the present invention, in the MIMO-OFDM system, the frequencies of two adjacent subcarriers on the antenna are f ₀ and f ₁ respectively, and the corresponding frequency responses are H ⁰ and H ¹ , and the subcarriers f ₀ and The received signals on f ₁ are respectively:

$[\begin{matrix} {r r}_{00}^{((00))} \\ {r r}_{00}^{((11))} \end{matrix}] = = {H h}^{00} [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ {n no}_{00}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{00} & {H h}_{0101}^{00} \\ {GH GH}_{1010}^{00} & {GH GH}_{1111}^{00} \end{matrix}] [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ {n no}_{00}^{((11))} \end{matrix}]$

和and

$[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \end{matrix}] = = {H h}^{11} [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ {n no}_{11}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{11} & {H h}_{0101}^{11} \\ {GH GH}_{1010}^{11} & {GH GH}_{1111}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ {n no}_{11}^{((11))} \end{matrix}],,$

本发明的有益效果在于：本发明所述的MIMO-OFDM系统中Alamouti码的检测方法考虑到了接收天线之间噪声和增益的不平衡对信号检测的严重影响，其相对于传统Alamouti码的检测方法获得了较大的性能增益，提高了检测性能。The beneficial effect of the present invention is that: the detection method of Alamouti code in the MIMO-OFDM system of the present invention has considered the serious impact of noise and gain imbalance between receiving antennas on signal detection, and its detection method with respect to traditional Alamouti code A large performance gain is obtained and the detection performance is improved.

附图说明Description of drawings

图1为本发明所述的MIMO-OFDM系统中Alamouti码的检测方法的流程示意图。FIG. 1 is a schematic flowchart of a method for detecting Alamouti codes in a MIMO-OFDM system according to the present invention.

具体实施方式Detailed ways

本发明公开了一种MIMO-OFDM系统中Alamouti码的检测方法，该方法考虑了接收天线之间噪声不平衡和接收天线增益不平衡的问题。在实际系统中，各个接收天线使用独立的射频模块，如果射频模块的原件的规格不同，其产生的噪声是不同的；而且不同的接收天线也可能受到不同程度的干扰，这就导致了接收天线之间噪声的不平衡。同时，由于在实际系统中各个接收天线使用独立的自动增益控制(Automatic Gain Control,AGC)模块，以提供给后面的模拟数字转换器(Analog to Digital Converter,ADC)一个固定幅度的模拟信号，但是由于信道衰落的独立性，使得每根接收天线AGC调整的增益不同，导致接收天线之间增益的不平衡。另外由于AGC控制的非理想性，导致ADC的量化噪声也是不平衡的。接收天线之间噪声和增益的不平衡如果在信号检测时不能处理得当，就会严重影响到检测性能。本发明中提出的MIMO-OFDM系统中Alamouti码的检测方法考虑到了这些因素，提出的检测方法相对于传统Alamouti码的检测方法获得了较大的性能增益，提高了检测性能。本发明可以应用在使用Alamouti编码的通信系统中，如3GPP LTE(LTE-A)，IEEE WiMAX等。本发明适用于发送天线数为2或者2的整数倍，接收天线数为任意的情况。The invention discloses a method for detecting Alamouti codes in a MIMO-OFDM system. The method considers the problems of noise imbalance between receiving antennas and receiving antenna gain imbalance. In an actual system, each receiving antenna uses an independent RF module. If the original specifications of the RF module are different, the noise generated by it is different; and different receiving antennas may also be interfered to varying degrees, which leads to the noise imbalance. At the same time, since each receiving antenna in the actual system uses an independent automatic gain control (Automatic Gain Control, AGC) module to provide a fixed-amplitude analog signal to the subsequent analog-to-digital converter (Analog to Digital Converter, ADC), but Due to the independence of channel fading, the gain adjusted by the AGC of each receiving antenna is different, resulting in an unbalanced gain among the receiving antennas. In addition, due to the non-ideality of the AGC control, the quantization noise of the ADC is also unbalanced. The imbalance of noise and gain between receiving antennas will seriously affect the detection performance if it is not handled properly during signal detection. The detection method of the Alamouti code in the MIMO-OFDM system proposed in the present invention takes these factors into consideration. Compared with the traditional Alamouti code detection method, the proposed detection method obtains a larger performance gain and improves the detection performance. The present invention can be applied in the communication system that uses Alamouti coding, as 3GPP LTE (LTE-A), IEEE WiMAX etc. The present invention is applicable to situations where the number of transmitting antennas is 2 or an integer multiple of 2 and the number of receiving antennas is arbitrary.

下面结合附图对本发明的具体实施方式作进一步详细说明。The specific implementation manners of the present invention will be described in further detail below in conjunction with the accompanying drawings.

实施例一Embodiment one

本实施例提供一种MIMO-OFDM系统中Alamouti码的检测方法，该方法要解决的问题是，在考虑到接收天线之间噪声和增益的不平衡时，如何设计MIMO-OFDM系统中Alamouti码的检测方法，使得检测性能相对于传统没有考虑到这个问题时的Alamouti码检测方法有明显的增益。This embodiment provides a method for detecting Alamouti codes in a MIMO-OFDM system. The problem to be solved by this method is how to design the Alamouti codes in a MIMO-OFDM system when considering the imbalance of noise and gain between receiving antennas. The detection method makes the detection performance have obvious gains compared with the traditional Alamouti code detection method that does not consider this problem.

基于该问题，本实施例所述的MIMO-OFDM系统中Alamouti码检测方法的主要内容为：Based on this problem, the main content of the Alamouti code detection method in the MIMO-OFDM system described in this embodiment is:

发送端和接收端都配备有2根天线，每根接收天线使用独立的射频链路，同时为了不失一般性，本实施例不指定Alamouti码是在时域或者频域进行编码，而是说在两个间隔上进行编码。调制后的复信号(s₀,s₁)经过Alamouti编码后再在多径衰落信道上进行传输。为了表征两根接收天线的增益不同，本实施例引入变量G，G表示接收天线1相对于接收天线0的射频链路增益(包括AGC的增益)。两个间隔内的接收信号可以分别表示为：Both the transmitting end and the receiving end are equipped with two antennas, and each receiving antenna uses an independent radio frequency link. At the same time, in order not to lose generality, this embodiment does not specify that the Alamouti code is coded in the time domain or the frequency domain, but that Encode on two intervals. The modulated complex signal (s ₀ , s ₁ ) is transmitted on the multipath fading channel after Alamouti coding. In order to characterize the difference in gain between the two receiving antennas, this embodiment introduces a variable G, where G represents the radio frequency link gain (including AGC gain) of receiving antenna 1 relative to receiving antenna 0 . The received signals in the two intervals can be expressed as:

$[\begin{matrix} {r r}_{00}^{((00))} \\ {r r}_{00}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{00} & {H h}_{0101}^{00} \\ G G {H h}_{1010}^{00} & {GH GH}_{1111}^{00} \end{matrix}] [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ G G {n no}_{00}^{((11))} \end{matrix}] - - - - - - ((11))$

和and

$[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{11} & {H h}_{0101}^{11} \\ G G {H h}_{1010}^{11} & {GH GH}_{1111}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ G G {n no}_{11}^{((11))} \end{matrix}] - - - - - - ((22))$

其中，*为复共轭符号。在式(1)和式(2)中，表示接收天线j上在间隔i内的接收信号。表示发射天线k和接收天线m之间的信道响应的独立随机变量。表示在间隔i内接收天线j上的零均值的加性高斯噪声。的方差为i＝0,1且 where * is the complex conjugate symbol. In formula (1) and formula (2), Denotes the received signal on receiving antenna j in interval i. An independent random variable representing the channel response between transmit antenna k and receive antenna m. Represents additive Gaussian noise with zero mean on receive antenna j over interval i. The variance of i=0,1 and

一般来说，G的值并不等于1，因为两根接收天线的信道是独立衰落的，同时，为了给后续模块ADC提供一个恒幅值的模拟信号，接收天线多使用独立的AGC进行增益控制。再者，由于AGC控制的非理想性，两根接收天线上的ADC的量化导致的量化噪声也不相等。Generally speaking, the value of G is not equal to 1, because the channels of the two receiving antennas are independently fading. At the same time, in order to provide a constant amplitude analog signal to the subsequent module ADC, the receiving antenna mostly uses an independent AGC for gain control. . Furthermore, due to the non-ideality of the AGC control, the quantization noises caused by the quantization of the ADCs on the two receiving antennas are also not equal.

本发明中提出的MIMO-OFDM系统中Alamouti码的检测方法为：在传统的Alamouti码检测方法中引入加权因子，以补偿接收天线之间射频链路噪声和增益的不平衡。定义变量a₀＝1，G₀＝1，检测信号可以表示为：The detection method of the Alamouti code in the MIMO-OFDM system proposed in the present invention is as follows: a weighting factor is introduced into the traditional Alamouti code detection method to compensate for the imbalance of radio frequency link noise and gain between receiving antennas. Define variable a ₀ =1, G ₀ =1, the detection signal can be expressed as:

$\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {H h}_{0000}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1010}^{00 * *} {r r}_{00}^{((11))} + + {H h}_{0101}^{11} {r r}_{11}^{((00)) * *} + + w w {GH GH}_{1111}^{11} {r r}_{11}^{((11)) * *} \\ {\overset{~ ~}{s the s}}_{11} = = {H h}_{0101}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1111}^{00 * *} {r r}_{00}^{((11))} - - {H h}_{0000}^{11} {r r}_{11}^{((00)) * *} - - w w {GH GH}_{1010}^{11} {r r}_{11}^{((11)) * *} \end{matrix} - - - - - - ((33))$

其中加权因子w通过下式计算：The weighting factor w is calculated by the following formula:

w_j＝(G_ja_j)^-1,j＝0,1 (4)w _j =(G _j a _j ) ^-1 ,j=0,1 (4)

通过加权，使得最后在进行检测时，所有天线的噪声能量相等，也就是平衡了天线之间的噪声能量。对于接收端配备了更多根接收天线的情况，上面的式(3)和式(4)都可以直接推广。By weighting, the noise energy of all antennas is equal when detection is finally performed, that is, the noise energy among the antennas is balanced. For the case where the receiving end is equipped with more receiving antennas, the above equations (3) and (4) can be directly extended.

实施例二Embodiment two

本实施例提供的场景为：接收端和发射端都配备了2根天线，并且在OFDM子载波上使用了Alamouti编码。The scenario provided in this embodiment is: both the receiving end and the transmitting end are equipped with two antennas, and Alamouti coding is used on OFDM subcarriers.

本实施例所述的MIMO-OFDM系统Alamouti码的检测方法为：设相邻的两个子载波频率分别为f₀和f₁，相应的频率响应为H⁰和H¹。子载波f₀和f₁上的接收信号分别为：The detection method of the Alamouti code in the MIMO-OFDM system described in this embodiment is as follows: set the frequencies of two adjacent subcarriers as f ₀ and f ₁ respectively, and the corresponding frequency responses as H ⁰ and H ¹ . The received signals on subcarriers f ₀ and f ₁ are:

$[\begin{matrix} {r r}_{00}^{((00))} \\ {r r}_{00}^{((11))} \end{matrix}] = = {H h}^{00} [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ G G {n no}_{00}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{00} & {H h}_{0101}^{00} \\ {GH GH}_{1010}^{00} & {GH GH}_{1111}^{00} \end{matrix}] [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ {Gn Gn}_{00}^{((11))} \end{matrix}] - - - - - - ((55))$

和and

$[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \end{matrix}] = = {H h}^{11} [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ G G {n no}_{11}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{11} & {H h}_{0101}^{11} \\ {GH GH}_{1010}^{11} & {GH GH}_{1111}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ {Gn Gn}_{11}^{((11))} \end{matrix}] - - - - - - ((66))$

G_i表示接收天线1相对于接收天线0的增益。接收天线0和接收天线1的噪声方差分别为和且满足则本实施例中提出的检测信号可以表示为G _i represents the gain of receiving antenna 1 relative to receiving antenna 0 . The noise variances of receiving antenna 0 and receiving antenna 1 are respectively and and satisfied Then the detection signal proposed in this embodiment can be expressed as

$\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {H h}_{0000}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1010}^{00 * *} {r r}_{00}^{((11))} + + {H h}_{0101}^{11} {r r}_{11}^{((00)) * *} + + w w {GH GH}_{1111}^{11} {r r}_{11}^{((11)) * *} \\ {\overset{~ ~}{s the s}}_{11} = = {H h}_{0101}^{00 * *} {r r}_{00}^{((00))} + + w w {GH GH}_{1111}^{00 * *} {r r}_{00}^{((11))} - - {H h}_{0000}^{11} {r r}_{11}^{((00)) * *} - - w w {GH GH}_{1010}^{11} {r r}_{11}^{((11)) * *} \end{matrix} - - - - - - ((77))$

其中加权因子w满足where the weighting factor w satisfies

w_j＝(G_ja_j)^-1,j＝0,1。 (8)w _j =(G _j a _j ) ⁻¹ , j=0,1. (8)

实施例三Embodiment three

本发明所要解决的问题是：在分集径之间噪声、增益不平衡的情况下，设计有效地Alamouti码检测方法，以提高检测性能。The problem to be solved by the present invention is to design an effective Alamouti code detection method in the case of unbalanced noise and gain among diversity paths, so as to improve the detection performance.

本实施例提出的MIMO-OFDM系统中Alamouti码的检测方法是通过对接收信号进行加权，使得最终的接收天线上噪声能量相等，以获得相对于原始的Alamouti码的检测方法更好的检测性能。本发明提出的MIMO-OFDM系统中Alamouti码检测方法的主要思想在于在检测中调整接收信号幅度，使得调整后的各接收天线的信号中噪声能量相等。The detection method of the Alamouti code in the MIMO-OFDM system proposed in this embodiment is to weight the received signal so that the noise energy on the final receiving antenna is equal, so as to obtain better detection performance than the original detection method of the Alamouti code. The main idea of the Alamouti code detection method in the MIMO-OFDM system proposed by the present invention is to adjust the amplitude of the received signal during detection, so that the noise energy in the adjusted signal of each receiving antenna is equal.

本实施例即为实施例一的推广，其与实施例一的区别在于，发送端配备2的倍数根天线，接收端配备有Nr根天线，两个间隔内的接收信号分别表示为：This embodiment is the promotion of Embodiment 1. The difference between it and Embodiment 1 is that the transmitting end is equipped with multiple antennas of 2, and the receiving end is equipped with Nr antennas. The received signals in the two intervals are expressed as:

$[\begin{matrix} {r r}_{00}^{((00))} \\ {r r}_{00}^{((11))} \\ . . \\ . . \\ . . \\ {r r}_{00}^{((j j))} \\ . . \\ . . \\ . . \\ {r r}_{00}^{((Nr Nr - - 11))} \end{matrix}] = = [\begin{matrix} {G G}_{00} {H h}_{0000}^{00} & {G G}_{00} {H h}_{0101}^{00} \\ {G G}_{11} {H h}_{1010}^{00} & {G G}_{11} {H h}_{1111}^{00} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{j j} {H h}_{j j 00}^{00} & {G G}_{j j} {H h}_{j j 11}^{00} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,0 1,0}^{00} & {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,1 1,1}^{00} \end{matrix}] [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {G G}_{00} {n no}_{00}^{((00))} \\ {G G}_{11} {n no}_{00}^{((11))} \\ . . \\ . . \\ . . \\ {G G}_{j j} {n no}_{00}^{((j j))} \\ . . \\ . . \\ . . \\ {G G}_{Nr Nr - - 11} {n no}_{00}^{((Nr Nr - - 11))} \end{matrix}] - - - - - - ((99))$

和and

$[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \\ . . \\ . . \\ . . \\ {r r}_{11}^{((j j))} \\ . . \\ . . \\ . . \\ {r r}_{11}^{((Nr Nr - - 11))} \end{matrix}] = = [\begin{matrix} {G G}_{00} {H h}_{0000}^{11} & {G G}_{00} {H h}_{0101}^{11} \\ {G G}_{11} {H h}_{1010}^{11} & {G G}_{11} {H h}_{1111}^{11} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{j j} {H h}_{j j 00}^{11} & {G G}_{j j} {H h}_{j j 11}^{11} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,0 1,0}^{11} & {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,1 1,1}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {G G}_{00} {n no}_{11}^{((00))} \\ {G G}_{11} {n no}_{11}^{((11))} \\ . . \\ . . \\ . . \\ {G G}_{j j} {n no}_{11}^{((j j))} \\ . . \\ . . \\ . . \\ {G G}_{Nr Nr - - 11} {n no}_{11}^{((Nr Nr - - 11))} \end{matrix}] - - - - - - ((1010))$

其中G_j表示接收天线j(j＝0,1,…,Nr-1)相对于接收天线0的射频链路增益，*为复共轭符号，表示接收天线j上在间隔i内的接收信号，表示发射天线k和接收天线m之间的信道响应的独立随机变量，表示在间隔i内接收天线j上的零均值的加性高斯噪声，的方差为i＝0,1,…,Nr-1且s_k表示Alamouti编码之前的发送信号；s_k的下标k表示第k个信号；where G _j represents the RF link gain of receiving antenna j (j=0,1,…,Nr-1) relative to receiving antenna 0, * is the complex conjugate symbol, Denotes the received signal on receiving antenna j in interval i, An independent random variable representing the channel response between transmit antenna k and receive antenna m, represents zero-mean additive Gaussian noise over receive antenna j in interval i, The variance of i=0,1,...,Nr-1 and s _k represents the transmitted signal before Alamouti encoding; the subscript k of s _k represents the kth signal;

$\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {Σ Σ}_{j j = = 00}^{Nr Nr - - 11} (({w w}_{j j} {G G}_{j j} {H h}_{j j 00}^{00 * *} {r r}_{00}^{((j j))} + + {w w}_{j j} {G G}_{j j} {H h}_{j j 11}^{11} {r r}_{11}^{((j j)) * *})) \\ {\overset{~ ~}{s the s}}_{11} = = {Σ Σ}_{j j = = 00}^{Nr Nr - - 11} (({w w}_{j j} {G G}_{j j} {H h}_{j j 11}^{00 * *} {r r}_{00}^{((j j))} - - {w w}_{j j} {G G}_{j j} {H h}_{j j 00}^{11} {r r}_{11}^{((j j)) * *})) \end{matrix} - - - - - - ((1111))$

其中加权因子w为：where the weighting factor w is:

w_j＝(G_ja_j)^-1，j＝0,1,…,Nr-1 (12)w _j ＝(G _j a _j ) ^-1 ，j＝0,1,…,Nr-1 (12)

本发明的描述和应用是说明性的，并非想将本发明的范围限制在上述实施例中。这里所披露的实施例的变形和改变是可能的，对于那些本领域的普通技术人员来说实施例的替换和等效的各种部件是公知的。本领域技术人员应该清楚的是，在不脱离本发明的精神或本质特征的情况下，本发明可以以其他形式、结构、布置、比例，以及用其他元件、材料和部件来实现。The description and application of the present invention are illustrative and are not intended to limit the scope of the present invention to the examples described above. Variations and changes to the embodiments disclosed herein are possible, and substitutions and equivalents for various components of the embodiments are known to those of ordinary skill in the art. It should be clear to those skilled in the art that the present invention can be realized in other forms, structures, arrangements, proportions, and with other elements, materials and components without departing from the spirit or essential characteristics of the present invention.

Claims

1. the detection method of Alamouti code in a kind of MIMO-OFDM system, it is characterized in that: sending end is equipped with 2 antennas, and receiving end is equipped with Nr root antennas, and the receiving signal in two intervals is represented as respectively:

[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \\ . \\ . \\ . \\ r_{0}^{(j)} \\ . \\ . \\ . \\ r_{0}^{(Nr - 1)} \end{matrix}] = [\begin{matrix} G_{0} h_{00}^{0} & G_{0} G_{01}^{0} \\ G_{1} h_{10}^{0} & G_{1} h_{11}^{0} \\ . & . \\ . & . \\ . & . \\ G_{j} h_{j 0}^{0} & G_{j} h_{j 1}^{0} \\ . & . \\ . & . \\ . & . \\ G_{Nr - 1} h_{Nr - 1,0}^{0} & G_{Nr - 1} h_{Nr - 1,1}^{0} \end{matrix}] [\begin{matrix} {the s}_{0} \\ {the s}_{1} \end{matrix}] + [\begin{matrix} G_{0} {no}_{0}^{(0)} \\ G_{1} {no}_{0}^{(1)} \\ . \\ . \\ . \\ G_{j} {no}_{0}^{(j)} \\ . \\ . \\ . \\ G_{Nr - 1} {no}_{0}^{(Nr - 1)} \end{matrix}]

and

[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \\ . . \\ . . \\ . . \\ {r r}_{11}^{((j j))} \\ . . \\ . . \\ . . \\ {r r}_{11}^{((Nr Nr - - 11))} \end{matrix}] = = [\begin{matrix} {G G}_{00} {H h}_{0000}^{11} & {G G}_{00} {G G}_{0101}^{11} \\ {G G}_{11} {H h}_{1010}^{11} & {G G}_{11} {H h}_{1111}^{11} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{j j} {H h}_{1010}^{11} & 11 {G G}_{j j} {H h}_{j j 11}^{11} \\ . . & . . \\ . . & . . \\ . . & . . \\ {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,0 1,0}^{11} & {G G}_{Nr Nr - - 11} {H h}_{Nr Nr - - 1,1 1,1}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {G G}_{00} {n no}_{11}^{((00))} \\ {G G}_{11} {n no}_{11}^{((11))} \\ . . \\ . . \\ . . \\ {G G}_{j j} {n no}_{11}^{((j j))} \\ . . \\ . . \\ . . \\ {G G}_{Nr Nr - - 11} {n no}_{11}^{((Nr Nr - - 11))} \end{matrix}],,

where G _j represents the RF link gain of receiving antenna j relative to receiving antenna 0, j=0,1,...,Nr-1, * is the complex conjugate symbol, Denotes the received signal on receiving antenna j in interval i, An independent random variable representing the channel response between transmit antenna k and receive antenna m, represents zero-mean additive Gaussian noise over receive antenna j in interval i, The variance of j=0,1,...,Nr-1 and s _k represents the transmitted signal before Alamouti encoding, and the subscript k of s _k represents the kth signal;

Define variable a ₀ =1, G ₀ =1, and the detection signal is expressed as:

\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {Σ Σ}_{j j = = 00}^{Nr Nr - - 11} (({w w}_{j j} {G G}_{j j} {H h}_{j j 00}^{00 * *} {r r}_{00}^{((j j))} + + {w w}_{j j} {G G}_{j j} {H h}_{j j 11}^{11} {r r}_{11}^{{((j j))}^{* *}})) \\ {\overset{~ ~}{s the s}}_{11} = = {Σ Σ}_{j j = = 00}^{Nr Nr - - 11} (({w w}_{j j} {G G}_{j j} {H h}_{j j 11}^{00 * *} {r r}_{00}^{((j j))} - - {w w}_{j j} {G G}_{j j} {H h}_{j j 00}^{11} {r r}_{11}^{{((j j))}^{* *}})) \end{matrix}

The weighting factor w _j is: w _j =(G _j a _j ) ^-1 , j=0,1,...,Nr-1.

2. the detection method of Alamouti code in the MIMO-OFDM system according to claim 1 is characterized in that: Nr=2, sending end and receiving end are all equipped with 2 antennas, and the received signal in two intervals is represented as respectively :

[\begin{matrix} r_{0}^{(0)} \\ r_{0}^{(1)} \end{matrix}] = [\begin{matrix} h_{00}^{0} & h_{01}^{0} \\ G h_{10}^{0} & G h_{11}^{0} \end{matrix}] [\begin{matrix} {the s}_{0} \\ {the s}_{1} \end{matrix}] + [\begin{matrix} {no}_{0}^{(0)} \\ G {no}_{0}^{(1)} \end{matrix}]

and

[\begin{matrix} r_{1}^{(0)} \\ r_{1}^{(1)} \end{matrix}] = [\begin{matrix} h_{00}^{1} & h_{01}^{1} \\ G h_{10}^{1} & G h_{11}^{1} \end{matrix}] [\begin{matrix} {- the s}_{1}^{*} \\ {the s}_{0}^{*} \end{matrix}] + [\begin{matrix} {no}_{1}^{(0)} \\ G {no}_{1}^{(1)} \end{matrix}],

Among them, G represents the gain of receiving antenna 1 relative to receiving antenna 0, and the noise variances of receiving antenna 0 and receiving antenna 1 are respectively and and satisfied The detection signal is expressed as:

\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {H h}_{0000}^{00 * *} {r r}_{00}^{((00))} + + wG wxya {H h}_{1010}^{00 * *} {r r}_{00}^{((11))} + + {H h}_{0101}^{11} {r r}_{11}^{((00)) * *} + + wG wxya {H h}_{1111}^{11} {r r}_{11}^{((11)) * *} \\ {\overset{~ ~}{s the s}}_{11} = = {H h}_{0101}^{00 * *} {r r}_{00}^{((00))} + + wG wxya {H h}_{1111}^{00 * *} {r r}_{00}^{((11))} - - {H h}_{0000}^{11} {r r}_{11}^{((00)) * *} - - wG wxya {H h}_{1010}^{11} {r r}_{11}^{((11)) * *} \end{matrix}

The weighting factor w is: w _j =(G _j a _j ) ^-1 , j=0,1.

3. the detection method of Alamouti code in the MIMO-OFDM system according to claim 1 is characterized in that: in the MIMO-OFDM system, two adjacent subcarrier frequencies on the antenna are f ₀ and f ₁ respectively, corresponding The frequency responses are H ⁰ and H ¹ , and the received signals on subcarriers f ₀ and f ₁ are:

[\begin{matrix} {r r}_{00}^{((00))} \\ {r r}_{00}^{((11))} \end{matrix}] = = {H h}^{00} [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ G G {n no}_{00}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{00} & {H h}_{0101}^{00} \\ G G {H h}_{1010}^{00} & G G {H h}_{1111}^{00} \end{matrix}] [\begin{matrix} {s the s}_{00} \\ {s the s}_{11} \end{matrix}] + + [\begin{matrix} {n no}_{00}^{((00))} \\ G G {n no}_{00}^{((11))} \end{matrix}]

and

[\begin{matrix} {r r}_{11}^{((00))} \\ {r r}_{11}^{((11))} \end{matrix}] = = {H h}^{11} [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ G G {n no}_{11}^{((11))} \end{matrix}] = = [\begin{matrix} {H h}_{0000}^{11} & {H h}_{0101}^{11} \\ G G {H h}_{1010}^{11} & G G {H h}_{1111}^{11} \end{matrix}] [\begin{matrix} - - {s the s}_{11}^{* *} \\ {s the s}_{00}^{* *} \end{matrix}] + + [\begin{matrix} {n no}_{11}^{((00))} \\ G G {n no}_{11}^{((11))} \end{matrix}],,

\{\begin{matrix} {\overset{~ ~}{s the s}}_{00} = = {H h}_{0000}^{00 * *} {r r}_{00}^{((00))} + + wG wxya {H h}_{1010}^{00 * *} {r r}_{00}^{((11))} + + {H h}_{0101}^{11} {r r}_{11}^{((00)) * *} + + wG wxya {H h}_{1111}^{11} {r r}_{11}^{((11)) * *} \\ {\overset{~ ~}{s the s}}_{11} = = {H h}_{0101}^{00 * *} {r r}_{00}^{((00))} + + wG wxya {H h}_{1111}^{00 * *} {r r}_{00}^{((11))} - - {H h}_{0000}^{11} {r r}_{11}^{((00)) * *} - - wG wxya {H h}_{1010}^{11} {r r}_{11}^{((11)) * *} \end{matrix}

The weighting factor w is:

w_{j} = {(G_{j} a_{j})}^{- 1}, j = 0,1 .