CN113079122B - Design method for truncating and extrapolating pilot frequency sequence in reconstructed multi-carrier signal - Google Patents
Design method for truncating and extrapolating pilot frequency sequence in reconstructed multi-carrier signalDownload PDFInfo
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Abstract
Translated fromChinese
Description
Translated fromChinese技术领域technical field
本发明属于无线通信技术领域，具体涉及一种截断与外推重构多载波信号中导频序列的设计方法。The invention belongs to the technical field of wireless communication, and in particular relates to a design method for truncating and extrapolating a pilot sequence in a reconstructed multi-carrier signal.
背景技术Background technique
随着通信系统的日益发展，海量数据对通信资源的需求量随之增长，5G通信高通量场景对于高效传输的需求推动了信号编码、调制技术、滤波器设计等一系列高频谱效率传输技术的发展。对于OFDM系统而言，由于正交系统满足奈奎斯特准则，通信效率主要靠增加调制阶数，减少循环前缀、保护间隔，或降低带外辐射等手段来提升，但这些手段也有相应的局限性。例如，高阶调制使得信号对噪声更加敏感，并且对通信设备的要求更高。此外，这些技术也不能实现从符号量级提升传输效率。由此，OFDM信号的截断与外推重构方法应运而生，该方法是基于OFDM信号频带受限(带限)的特性，结合了带限信号外推思想而形成的一种新的高效传输方法。在发送端，对原始的OFDM信号截断后并发送；在接收端，通过对接收到的部分信号反复应用傅里叶变换及反变换、滤波、替换的迭代过程重构出整段OFDM信号。该方法能提升通信效率的代价与前提是通过发送端对原始信号截断，引入自干扰为代价，但接收端的重构过程基于外推方法恢复信号，尽量减少自干扰引起的信号畸变。With the increasing development of communication systems, the demand for communication resources of massive data increases accordingly. The demand for efficient transmission in high-throughput scenarios of 5G communication has promoted a series of transmission technologies with high spectral efficiency such as signal coding, modulation technology, and filter design. development of. For the OFDM system, since the orthogonal system satisfies the Nyquist criterion, the communication efficiency is mainly improved by increasing the modulation order, reducing the cyclic prefix, the guard interval, or reducing the out-of-band radiation, but these methods also have corresponding limitations. sex. For example, higher order modulation makes the signal more sensitive to noise and more demanding on communication equipment. In addition, these techniques cannot achieve the improvement of transmission efficiency from the symbol level. Therefore, the truncation and extrapolation reconstruction method of OFDM signal came into being. method. At the transmitting end, the original OFDM signal is truncated and sent; at the receiving end, the entire OFDM signal is reconstructed by repeatedly applying Fourier transform, inverse transform, filtering, and iterative processes to the received part of the signal. The cost and premise that this method can improve the communication efficiency is that the original signal is truncated by the transmitting end and self-interference is introduced, but the reconstruction process of the receiving end is based on the extrapolation method to restore the signal to minimize the signal distortion caused by self-interference.
众所周知，信道估计是使得后续信号检测及译码过程的基础，在截断与外推重构多载波传输中，信道估计更是准确重构的基础。常用于OFDM信道估计的导频包括块状导频、梳状导频等。块状导频可视作一个完整的OFDM符号，每个OFDM符号的所有子载波都用于传输导频符号，它能够准确地估计带宽内各子载波上的信道信息，适用于频率选择性信道；而梳状导频能够更适应快时变信道的变化，但需要通过内插的方法得到整个频带内的信道信息。对于压缩OFDM系统而言，也可以采用导频辅助的信道估计方法。如果将导频信号与发送的数据一起进行压缩传输，势必会产生导频所在频点上的自干扰，而这种自干扰会对信道估计结果产生难以消除的影响，针对此问题尚未存在相应的导频插入方法设计。It is well known that channel estimation is the basis for subsequent signal detection and decoding processes. In truncation and extrapolation reconstruction of multi-carrier transmission, channel estimation is the basis for accurate reconstruction. Pilots commonly used for OFDM channel estimation include block pilots, comb pilots, and the like. The block pilot can be regarded as a complete OFDM symbol. All sub-carriers of each OFDM symbol are used to transmit pilot symbols. It can accurately estimate the channel information on each sub-carrier within the bandwidth and is suitable for frequency selective channels. ; while the comb-shaped pilot frequency can better adapt to the change of the fast time-varying channel, but it needs to obtain the channel information in the whole frequency band by means of interpolation. For compressed OFDM systems, a pilot-assisted channel estimation method can also be used. If the pilot signal is compressed and transmitted together with the transmitted data, it will inevitably generate self-interference at the frequency point where the pilot is located, and this self-interference will have a difficult to eliminate influence on the channel estimation results. There is no corresponding solution to this problem. Pilot insertion method design.
发明内容SUMMARY OF THE INVENTION
本发明的目的是为解决采用传统导频的压缩OFDM系统中，被压缩的导频经重构后无法消除自干扰，进而导致对信道估计的准确性差的问题，而提出了一种截断与外推重构多载波信号中导频序列的设计方法。The purpose of the present invention is to solve the problem that self-interference cannot be eliminated after the compressed pilot frequency is reconstructed in the compressed OFDM system using the traditional pilot frequency, thus resulting in poor accuracy of channel estimation, and proposes a truncation and external A method for designing pilot sequences in reconstructed multi-carrier signals.
本发明为解决上述技术问题所采取的技术方案是：The technical scheme that the present invention takes to solve the above-mentioned technical problems is:
基于本发明的一个方面，一种截断与外推重构多载波信号中导频序列的设计方法，所述方法具体包括以下步骤：Based on one aspect of the present invention, a design method for truncating and extrapolating a pilot sequence in a reconstructed multi-carrier signal, the method specifically includes the following steps:
在发送端at the sender
步骤一、生成一组长度为Np的梳状导频序列，将生成的梳状导频序列作为压缩OFDM系统的导频序列xp；
步骤二、对数据序列xd进行星座点映射后，再对映射结果进行串/并转换，获得串/并转换后的结果；Step 2: After constellation point mapping is performed on the data sequence xd , serial/parallel conversion is performed on the mapping result to obtain the result after the serial/parallel conversion;
其中，数据序列xd的长度为Nd；Wherein, the length of the data sequence xd is Nd ;
依据梳状导频模式将导频序列xp插入串/并转换后的结果中，即将梳状导频序列的导频符号隔点置零地均匀分布在串/并转换后的结果中，得到包含梳状导频的信号x，并对信号x进行N-IDFT变换，得到N-IDFT变换后的OFDM信号xOFDM；Insert the pilot sequence xp into the result after serial/parallel conversion according to the comb-shaped pilot pattern, that is, the pilot symbols of the comb-shaped pilot sequence are evenly distributed in the result after the serial/parallel conversion by setting zero points to get Include the signal x of the comb-shaped pilot, and perform N-IDFT transformation on the signal x to obtain the OFDM signal xOFDM after the N-IDFT transformation;
步骤三、将N-IDFT变换后的OFDM信号xOFDM通过截断滤波器ΦN，截取前N/2点信号，得到压缩OFDM符号xp1,comb；
将N-IDFT变换后的OFDM信号xOFDM的后LCP个点，作为压缩OFDM符号xp1,comb的循环前缀CP，得到插入循环前缀CP后的OFDM信号sp1,comb；Taking the last LCP points of the OFDM signal xOFDM transformed by the N-IDFT as the cyclic prefix CP of the compressed OFDM symbol xp1,comb to obtain the OFDM signal sp1,comb after inserting the cyclic prefix CP;
再对插入循环前缀CP后的OFDM信号sp1,comb进行并/串转换后，得到待发送的压缩OFDM符号SP，多个压缩OFDM符号形成数据帧，并发送；After performing parallel/serial conversion on the OFDM signals sp1,comb inserted with the cyclic prefix CP, a compressed OFDM symbol SP to be sent is obtained, and a plurality of compressed OFDM symbols form a data frame and are sent;
在接收端at the receiving end
步骤四、对接收信号进行同步，获得同步后的接收信号RP，并从RP中获取导频符号yP；Step 4: Synchronize the received signal, obtain the synchronized received signal RP , and obtain the pilot symbol yP from the R P;
步骤五、根据得到的导频符号yP进行信道估计，得到信道冲激响应h；
步骤六、根据得到的信道冲激响应h，对接收到的数据部分进行均衡及外推重构，再将外推重构所得信号进行后续检测，以恢复出发送端发送的数据。Step 6: Perform equalization and extrapolation reconstruction on the received data part according to the obtained channel impulse response h, and then perform subsequent detection on the signal obtained by the extrapolation reconstruction to recover the data sent by the transmitter.
基于本发明的另一个方面，一种截断与外推重构多载波信号中导频序列的设计方法，所述方法具体包括以下步骤：Based on another aspect of the present invention, a design method for truncating and extrapolating a pilot sequence in a reconstructed multi-carrier signal, the method specifically includes the following steps:
在发送端at the sender
步骤1、生成一组长度为N/2的块状导频序列，并对生成的块状导频序列进行隔点插零操作，使块状导频序列的长度补齐为N；
依次对补齐后的块状导频序列进行串/并转换和N-IDFT变换后，将N-IDFT变换后的块状导频序列xp1,block经过截断滤波器ΦN，得到压缩OFDM块状导频符号sp1,block；After performing serial/parallel conversion and N-IDFT transformation on the filled block pilot sequence in turn, pass the N-IDFT transformed block pilot sequence xp1,block through the truncation filter ΦN to obtain a compressed OFDM block shape pilot symbols sp1,block ;
并将N-IDFT变换后的块状导频序列xp1,block的后LCP个点作为压缩OFDM块状导频符号sp1,block的循环前缀CP，将循环前缀CP插入压缩OFDM块状导频符号，获得插入循环前缀CP后的块状导频符号；The last LCP points of the N-IDFT-transformed block pilot sequence xp1,block are used as the cyclic prefix CP of the compressed OFDM block pilot symbol sp1,block , and the cyclic prefix CP is inserted into the compressed OFDM block pilot. frequency symbol, obtain the block pilot symbol after inserting the cyclic prefix CP;
再对插入循环前缀CP后的块状导频符号进行并/串转换，得到并/串转换后的块状导频符号；Then, perform parallel/serial conversion on the block pilot symbol after inserting the cyclic prefix CP to obtain the block pilot symbol after the parallel/serial conversion;
步骤2、对信源比特数据xd进行星座点映射、S/P转换和N-IDFT后，得到初始数据符号xd1,block；并将初始数据符号通过截断滤波器ΦN，得到压缩OFDM数据符号sd1,block；
再将初始数据符号xd1,block的后LCP个点作为压缩OFDM数据符号sd1,block的循环前缀CP，将循环前缀CP插入压缩OFDM数据符号sd1,block中，得到插入循环前缀CP后的数据符号；Then take the last LCP points of the initial data symbol xd1,block as the cyclic prefix CP of the compressed OFDM data symbol sd1 ,block, insert the cyclic prefix CP into the compressed OFDM data symbol sd1,block , and obtain the inserted cyclic prefix CP. the data symbol;
并对插入循环前缀CP后的数据符号进行并/串转换，得到待发送的压缩OFDM数据符号，多个待发送的压缩OFDM数据符号形成待发送的数据帧；and performing parallel/serial conversion on the data symbols after inserting the cyclic prefix CP to obtain compressed OFDM data symbols to be sent, and a plurality of compressed OFDM data symbols to be sent to form a data frame to be sent;
步骤3、将步骤1获得的并/串转换后的块状导频符号以周期Tt插入步骤2获得的待发送的数据帧中，其中，Tt为T的整数倍，T表示一个OFDM数据符号的周期时长；
在接收端at the receiving end
步骤4、对接收信号进行同步，获得同步后的接收信号RP，并从RP中获取导频符号yP；Step 4: Synchronize the received signal, obtain the synchronized received signal RP , and obtain the pilot symbol yP from the R P;
步骤5、根据步骤4得到的导频符号yP进行信道估计，得到信道冲激响应h；
步骤6、根据步骤5得到的信道冲激响应h，对接收到的数据部分进行均衡及外推重构，再对外推重构所得信号进行后续检测，恢复出发送端发送的数据。Step 6: Perform equalization and extrapolation reconstruction on the received data part according to the channel impulse response h obtained in
本发明的有益效果是：本发明提出了一种截断与外推重构多载波信号中导频序列的设计方法，本发明针对压缩OFDM传输方法引入的自干扰影响导频辅助的信道估计的准确性问题，通过设计隔点置零的导频序列，降低压缩导频的畸变程度，提升信道估计的准确性。The beneficial effects of the present invention are as follows: the present invention proposes a design method for truncating and extrapolating a pilot sequence in a reconstructed multi-carrier signal, and the present invention affects the accuracy of the pilot-assisted channel estimation due to the self-interference introduced by the compressed OFDM transmission method. To solve the problem of stability, by designing a pilot sequence that is set to zero at intervals, the degree of distortion of the compressed pilot is reduced and the accuracy of channel estimation is improved.
附图说明Description of drawings
图1是8点未压缩的全1导频频谱示意图；Figure 1 is a schematic diagram of an 8-point uncompressed all-one pilot frequency spectrum;
图1中横坐标上的1～8代表每个子载波的中心频率，未压缩时，各个子载波间正交，即每个中心频率上的采样点为当前子载波的幅值，不存在其他子载波的干扰；1 to 8 on the abscissa in Figure 1 represent the center frequency of each subcarrier. When uncompressed, each subcarrier is orthogonal, that is, the sampling point on each center frequency is the amplitude of the current subcarrier, and there are no other subcarriers. Carrier interference;
图2是8点未经设计的压缩导频频谱示意图；Fig. 2 is the schematic diagram of 8-point undesigned compressed pilot frequency spectrum;
图2中的两条虚线分别代表了压缩导频第一/四个子载波采样点处包含自干扰的幅值。第一条虚线处可见，此时自干扰主要包括右侧相邻的第二个子载波的干扰，及其他偶数个子载波的干扰，则第一个压缩导频子载波处的自干扰幅值可表示为：The two dashed lines in FIG. 2 represent the amplitudes of the self-interference contained in the first/fourth subcarrier sampling points of the compressed pilot, respectively. It can be seen from the first dotted line. At this time, the self-interference mainly includes the interference of the second adjacent sub-carrier on the right and the interference of other even-numbered sub-carriers. The self-interference amplitude at the first compressed pilot sub-carrier can be expressed as for:
其中，Ik表示第k个子载波处受到的干扰，N表示导频子载波个数，2t遍历了N个子载波内的偶数子载波，sinc函数表示为
类似地，第二条虚线处由于处于中间位置，同时收到两侧相邻导频子载波的强烈干扰，并同时受到其他奇数子载波的干扰，则第四个压缩导频子载波处的自干扰幅值可表示为：Similarly, since the second dashed line is in the middle position, it receives strong interference from adjacent pilot subcarriers on both sides, and is interfered by other odd-numbered subcarriers at the same time. The interference amplitude can be expressed as:
其中，2t-1遍历了N个子载波内的奇数次子载波。Among them, 2t-1 traverses the odd-numbered sub-carriers in the N sub-carriers.
图3是本发明设计的8点插零导频频谱示意图；Fig. 3 is the schematic diagram of 8-point zero-insertion pilot frequency spectrum designed by the present invention;
图4是本发明设计的8点插零压缩导频频谱示意图；4 is a schematic diagram of an 8-point zero-interpolation compressed pilot frequency spectrum designed by the present invention;
与图2相对应地，图3中两条虚线的位置分别代表插零导频第一/四个子载波采样点处包含自干扰的幅值，而图4是对图3导频截断压缩后的第一/四个子载波采样点处包含自干扰的幅值。由图4可见，压缩OFDM信号进行信道估计时，只需要奇数次子载波处的导频信息(即图中第1、3、5、7子载波处)；虽然第4子载波处依然存在自干扰，但并不会影响信道估计的结果，这是因为第4子载波处的信道信息可以根据奇数次子载波的信道信息进行插值获得；Corresponding to Fig. 2, the positions of the two dotted lines in Fig. 3 represent the amplitudes of the self-interference contained in the first/fourth subcarrier sampling points of the zero-insertion pilot respectively, and Fig. 4 is the truncated and compressed pilot of Fig. 3. The magnitude of the self-interference is contained at the first/fourth subcarrier sampling points. It can be seen from Figure 4 that when compressing the OFDM signal for channel estimation, only the pilot information at the odd number of subcarriers is needed (that is, at the 1st, 3rd, 5th, and 7th subcarriers in the figure); interference, but it will not affect the result of channel estimation, because the channel information at the 4th subcarrier can be obtained by interpolation according to the channel information of the odd-numbered subcarriers;
图5是插入梳状导频的截断与外推重构多载波系统收发端流程图；Fig. 5 is the truncation and extrapolation reconstruction multi-carrier system transceiver flow chart of inserting comb pilot frequency;
图6是本发明中插入梳状导频的示意图；Fig. 6 is the schematic diagram of inserting comb pilot in the present invention;
由图6可见，对于采用梳状导频的系统，直接在单个符号中插入导频序列，在插入梳状导频的过程中，在前后各加零，以抵消非正交的数据对导频的影响；It can be seen from Figure 6 that for the system using comb pilots, the pilot sequence is directly inserted into a single symbol, and in the process of inserting comb pilots, zeros are added before and after to cancel the non-orthogonal data pair pilots. Impact;
图7是插入块状导频的截断与外推重构多载波系统收发端流程图；FIG. 7 is a flowchart of the truncation and extrapolation reconstruction multi-carrier system transceiver end of inserting block pilots;
图8是本发明中插入块状导频的示意图；8 is a schematic diagram of inserting block pilots in the present invention;
由图8可见，插入的块状导频符号隔点置零，因此在每个子载波频点处不存在自干扰，而数据部分由于未进行隔点置零操作，依然存在自干扰。It can be seen from FIG. 8 that the inserted block pilot symbols are set to zero at every interval, so there is no self-interference at each subcarrier frequency point, and the data part still has self-interference because the operation of zero-setting at every interval is not performed.
具体实施方式Detailed ways
具体实施方式一、结合图5说明本实施方式。本实施方式所述的一种截断与外推重构多载波信号中导频序列的设计方法，所述方法具体包括以下步骤：DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the present embodiment will be described with reference to FIG. 5 . A method for designing a pilot sequence in a truncated and extrapolated reconstructed multi-carrier signal described in this embodiment specifically includes the following steps:
在发送端at the sender
步骤一、生成一组长度为Np的梳状导频序列，将生成的梳状导频序列作为压缩OFDM系统的导频序列xp；
步骤二、对数据序列xd进行星座点映射后，再对映射结果进行串/并转换(S/P转换)，获得串/并转换后的结果；
其中，数据序列xd的长度为Nd；Wherein, the length of the data sequence xd is Nd ;
依据梳状导频模式将导频序列xp插入串/并转换后的结果中，即将梳状导频序列的导频符号隔点置零地均匀分布在串/并转换后的结果中，得到包含梳状导频的信号x，并对信号x进行N-IDFT变换(N点离散傅里叶逆变换)，得到N-IDFT变换后的OFDM信号xOFDM；Insert the pilot sequence xp into the result after serial/parallel conversion according to the comb-shaped pilot pattern, that is, the pilot symbols of the comb-shaped pilot sequence are evenly distributed in the result after the serial/parallel conversion by setting zero points to get Include the signal x of the comb-shaped pilot, and perform N-IDFT transformation (N-point inverse discrete Fourier transform) on the signal x to obtain the OFDM signal xOFDM after the N-IDFT transformation;
其中，IDFT过程可表达为Among them, the IDFT process can be expressed as
步骤三、将N-IDFT变换后的OFDM信号xOFDM通过截断滤波器ΦN，截取前N/2点信号，得到压缩OFDM符号xp1,comb；
将N-IDFT变换后的OFDM信号xOFDM的后LCP个点，作为压缩OFDM符号xp1,comb的循环前缀CP，得到插入循环前缀CP后的OFDM信号sp1,comb；Taking the last LCP points of the OFDM signal xOFDM transformed by the N-IDFT as the cyclic prefix CP of the compressed OFDM symbol xp1,comb to obtain the OFDM signal sp1,comb after inserting the cyclic prefix CP;
再对插入循环前缀CP后的OFDM信号sp1,comb进行并/串转换(P/S转换)后，得到待发送的压缩OFDM符号SP，多个(大于等于2个)压缩OFDM符号形成数据帧，并发送；After performing parallel/serial conversion (P /S conversion) on the OFDM signals sp1,comb after inserting the cyclic prefix CP, the compressed OFDM symbol SP to be sent is obtained, and multiple (greater than or equal to 2) compressed OFDM symbols form data frame, and send;
在接收端at the receiving end
步骤四、对接收信号进行同步，获得同步后的接收信号RP，并从RP中获取导频符号yP；Step 4: Synchronize the received signal, obtain the synchronized received signal RP , and obtain the pilot symbol yP from the R P;
步骤五、根据得到的导频符号yP进行信道估计，得到信道冲激响应h；
需要注意的是，对于不同的压缩传输通信场景，应采用不同的信道估计方法。例如，对于大规模的毫米波通信场景，传统参数估计的方法大多不适用，需采用基于压缩感知或深度学习的信道估计；而对于单天线或小规模天线的信道环境下，可采用传统的LS，MMSE，卡尔曼滤波信道估计方法等；It should be noted that for different compressed transmission communication scenarios, different channel estimation methods should be used. For example, for large-scale millimeter-wave communication scenarios, traditional parameter estimation methods are mostly inapplicable, and channel estimation based on compressed sensing or deep learning needs to be used; while for single-antenna or small-scale antenna channel environments, traditional LS can be used. , MMSE, Kalman filter channel estimation method, etc.;
步骤六、根据得到的信道冲激响应h，对接收到的数据部分进行均衡及外推重构，再将外推重构所得信号进行后续检测，以恢复出发送端发送的数据。Step 6: Perform equalization and extrapolation reconstruction on the received data part according to the obtained channel impulse response h, and then perform subsequent detection on the signal obtained by the extrapolation reconstruction to recover the data sent by the transmitter.
具体实施方式二：本实施方式与具体实施方式一不同的是，所述包含梳状导频的信号x的长度为N＝Np+Nd。Embodiment 2: The difference between this embodiment and
具体实施方式三：本实施方式与具体实施方式二不同的是，所述步骤一中生成一组长度为Np的梳状导频序列，所述梳状导频序列为PN序列、全一序列或随机序列。Embodiment 3: The difference between this embodiment and
针对多径信道，尤其在多天线系统中，采用相关性良好的PN序列作为导频序列；所述PN序列满足：For multipath channels, especially in multi-antenna systems, a PN sequence with good correlation is used as a pilot sequence; the PN sequence satisfies:
其中，pm为循环移位m位后的PN序列，pn为循环移位n位后的PN序列，
可通过生成器直接生成m序列、Gold序列、格雷序列等，幅值APN∈{-1,+1}。The generator can directly generate m-sequences, Gold sequences, Gray sequences, etc., with the amplitude APN ∈ {-1,+1}.
所述全一序列为
所述随机序列为xp＝randi(1,Np)。The random sequence is xp =randi(1,Np ).
具体实施方式四：结合图6说明本实施方式。本实施方式与具体实施方式三不同的是，所述包含梳状导频的信号x中，导频符号间隔小于信道的相干带宽。Embodiment 4: This embodiment is described with reference to FIG. 6 . The difference between this embodiment and the third embodiment is that in the signal x containing comb-shaped pilots, the pilot symbol interval is smaller than the coherence bandwidth of the channel.
其中，相干带宽由多径信道时延决定，指多径信道中任意两个频率分量具有强幅度相关性的频率范围。Among them, the coherence bandwidth is determined by the multipath channel delay, which refers to the frequency range in which any two frequency components in the multipath channel have strong amplitude correlation.
本实施方式在保证压缩传输的同时，抑制了导频信号由于压缩而产生的自干扰。虽然对导频进行隔点置零操作，但导频序列占用的时频资源并未增加。相对于不置零的导频序列，虽然有效点数减少，但自干扰造成的导频畸变被抑制。同时，由于置零操作并不需要复乘法等过程，发送端的计算复杂度并未提升。This embodiment suppresses the self-interference of the pilot signal due to the compression while ensuring the compressed transmission. Although the pilot frequency is set to zero at intervals, the time-frequency resource occupied by the pilot frequency sequence does not increase. Compared with the pilot sequence without zero setting, although the number of effective points is reduced, the pilot distortion caused by self-interference is suppressed. At the same time, since the zero-setting operation does not require processes such as complex multiplication, the computational complexity of the sender is not improved.
具体实施方式五：本实施方式与具体实施方式四不同的是，所述将N-IDFT变换后的OFDM信号xOFDM通过截断滤波器ΦN，截取前N/2点信号，得到压缩OFDM符号xp1,comb；其具体过程为：Embodiment 5: The difference between this embodiment and
步骤三一、生成截断滤波器ΦN：Step 31. Generate a truncation filter ΦN :
步骤三二、在时域上对N-IDFT变换后的OFDM信号xOFDM进行截断处理，得到压缩OFDM符号xp1,comb：Step 32: Perform truncation processing on the N-IDFT transformed OFDM signal xOFDM in the time domain to obtain the compressed OFDM symbol xp1,comb :
xp1,comb＝xOFDM·ΦN。xp1,comb =xOFDM ·ΦN .
需要注意的是，梳状导频的插入周期ff与信道最大时延拓展σmax的关系为It should be noted that the relationship between the insertion period ff of the comb pilot frequency and the maximum channel delay extension σmax is:
ff≤1/σmaxff ≤1/σmax
具体实施方式六：本实施方式与具体实施方式五不同的是，所述获取导频符号yP的具体过程为：Embodiment 6: The difference between this embodiment and
对同步后的接收信号RP进行N-DFT变换(N点离散傅里叶变换)，获得N-DFT变换后的结果；并在N-DFT变换后结果的频域上获取梳状导频频段。Perform N-DFT transform (N-point discrete Fourier transform) on the synchronized received signal RP to obtain the N-DFT transformed result; and obtain the comb-shaped pilot frequency band in the frequency domain of the N-DFT transformed result .
其中，DFT过程可表达为Among them, the DFT process can be expressed as
具体实施方式七、结合图7和图8说明本实施方式。本实施方式所述的一种截断与外推重构多载波信号中导频序列的设计方法，所述方法具体包括以下步骤：
在发送端at the sender
步骤1、生成一组长度为N/2的块状导频序列，并对生成的块状导频序列进行隔点插零操作，使块状导频序列的长度补齐为N；
依次对补齐后的块状导频序列进行串/并转换(S/P转换)和N-IDFT变换(N点离散傅里叶逆变换)后，将N-IDFT变换后的块状导频序列xp1,block经过截断滤波器ΦN，得到压缩OFDM块状导频符号sp1,block；After performing serial/parallel conversion (S/P conversion) and N-IDFT transform (N-point inverse discrete Fourier transform) on the filled block pilot sequence in turn, the block pilot after N-IDFT transform The sequence xp1,block is passed through the truncation filter ΦN to obtain the compressed OFDM block pilot symbolsp1,block ;
并将N-IDFT变换后的块状导频序列xp1,block的后LCP个点作为压缩OFDM块状导频符号sp1,block的循环前缀CP，将循环前缀CP插入压缩OFDM块状导频符号，获得插入循环前缀CP后的块状导频符号；The last LCP points of the N-IDFT-transformed block pilot sequence xp1,block are used as the cyclic prefix CP of the compressed OFDM block pilot symbol sp1,block , and the cyclic prefix CP is inserted into the compressed OFDM block pilot. frequency symbol, obtain the block pilot symbol after inserting the cyclic prefix CP;
再对插入循环前缀CP后的块状导频符号进行并/串转换(P/S转换)，得到并/串转换后的块状导频符号；Then perform parallel/serial conversion (P/S conversion) on the block-shaped pilot symbol after inserting the cyclic prefix CP to obtain the block-shaped pilot symbol after the parallel/serial conversion;
步骤2、对信源比特数据xd进行星座点映射、S/P转换和N-IDFT后，得到初始数据符号xd1,block；并将初始数据符号通过截断滤波器ΦN，得到压缩OFDM数据符号sd1,block；
再将初始数据符号xd1,block的后LCP个点作为压缩OFDM数据符号sd1,block的循环前缀CP，将循环前缀CP插入压缩OFDM数据符号sd1,block中，得到插入循环前缀CP后的数据符号；Then take the last LCP points of the initial data symbol xd1,block as the cyclic prefix CP of the compressed OFDM data symbol sd1 ,block, insert the cyclic prefix CP into the compressed OFDM data symbol sd1,block , and obtain the inserted cyclic prefix CP. the data symbol;
并对插入循环前缀CP后的数据符号进行并/串转换，得到待发送的压缩OFDM数据符号，多个(大于等于2个)待发送的压缩OFDM数据符号形成待发送的数据帧；and performing parallel/serial conversion on the data symbols after inserting the cyclic prefix CP to obtain compressed OFDM data symbols to be sent, and multiple (greater than or equal to 2) compressed OFDM data symbols to be sent form data frames to be sent;
步骤3、将步骤1获得的并/串转换后的块状导频符号以周期Tt插入步骤2获得的待发送的数据帧中；
在接收端at the receiving end
步骤4、对接收信号进行同步，获得同步后的接收信号RP，并从RP中获取导频符号yP；Step 4: Synchronize the received signal, obtain the synchronized received signal RP , and obtain the pilot symbol yP from the R P;
若采用块状导频的插入方式，在时域上周期截取接收信号中的块状导频时段，已知导频符号的插入周期为Tt；则对于RP，找到第一个导频块位置后，每隔Tt获得的完整符号，即为导频符号yP；If the block pilot insertion method is adopted, the block pilot period in the received signal is periodically intercepted in the time domain, and the insertion period of the pilot symbol is known to be Tt ; then for RP , find the first pilot block After the position, the complete symbol obtained every Tt is the pilot symbol yP ;
步骤5、根据步骤4得到的导频符号yP进行信道估计，得到信道冲激响应h；
步骤6、根据步骤5得到的信道冲激响应h，对接收到的数据部分进行均衡及外推重构，再对外推重构所得信号进行后续检测，恢复出发送端发送的数据。Step 6: Perform equalization and extrapolation reconstruction on the received data part according to the channel impulse response h obtained in
本实施方式是基于发送端过程而设计的，在压缩传输的非正交环境下，对不同的导频插入方式，采用不同的提取手段，提取的导频可以视为近似正交的关系；近似正交可以实现自干扰的近似消除，实现少导频数的更精准信道估计。This embodiment is designed based on the process of the transmitting end. In the non-orthogonal environment of compressed transmission, different extraction methods are used for different pilot insertion methods, and the extracted pilots can be regarded as an approximately orthogonal relationship; Orthogonality can achieve approximate elimination of self-interference and more accurate channel estimation with fewer pilots.
本发明中，在导频序列中：Np＝N,Nd＝0；在数据序列中：Np＝0,Nd＝N。In the present invention, in the pilot sequence: Np =N, Nd =0; in the data sequence: Np =0, Nd =N.
具体实施方式八：本实施方式与具体实施方式七不同的是，所述步骤1中生成一组长度为N/2的块状导频序列，所述导频序列为PN序列、全一序列或随机序列。Embodiment 8: The difference between this embodiment and
针对多径信道，尤其在多天线系统中，采用相关性良好的PN序列作为导频序列；所述PN序列满足：For multipath channels, especially in multi-antenna systems, a PN sequence with good correlation is used as a pilot sequence; the PN sequence satisfies:
其中，pm为循环移位m位后的PN序列，pn为循环移位n位后的PN序列，
可通过生成器直接生成m序列、Gold序列、格雷序列等，幅值APN∈{-1,+1}。The generator can directly generate m-sequences, Gold sequences, Gray sequences, etc., with the amplitude APN ∈ {-1,+1}.
所述全一序列为
所述随机序列为xp＝randi(1,Np)。The random sequence is xp =randi(1,Np ).
具体实施方式九：本实施方式与具体实施方式八不同的是，所述截断滤波器ΦN的形式为：Embodiment 9: The difference between this embodiment and
将导频序列xp1,block经过截断滤波器ΦN：Pass the pilot sequence xp1,block through the truncation filter ΦN :
sp1,block＝xp1,block·ΦNsp1,block ＝xp1,block ·ΦN
其中，sp1,block为压缩OFDM块状导频符号；Among them,sp1,block is the compressed OFDM block pilot symbol;
将初始数据符号xd1,block经过截断滤波器ΦN：Pass the initial data symbol xd1,block through the truncation filter ΦN :
sd1,block＝xd1,block·ΦNsd1,block = xd1,block ·ΦN
其中，sd1,block为压缩OFDM数据符号。Among them, sd1,block is the compressed OFDM data symbol.
具体实施方式十：本实施方式与具体实施方式九不同的是，所述周期Tt与信道最大多普勒频移fd的关系为：Tt≤1/fd。Embodiment 10: This embodiment differs from Embodiment 9 in that the relationship between the period Tt and the maximum Doppler frequency shift fd of the channel is: Tt ≤1/fd .
具体实施方式十一：本实施方式与具体实施方式十不同的是，所述周期Tt为T的整数倍，T表示一个OFDM数据符号的周期时长。Embodiment 11: This embodiment differs from Embodiment 10 in that the period Tt is an integer multiple of T, and T represents the period duration of one OFDM data symbol.
本发明在保证压缩传输的同时，阐述了插入不同导频的截断与外推重构多载波信号发送端设计方法。由于块状导频能够准确地估计带宽内各子载波上的信道信息，适用于频率选择性信道；而梳状导频能够更有效估计快时变信道，都具有一定的实际应用意义。While ensuring compressed transmission, the present invention expounds the design method of the multi-carrier signal transmitting end for truncation and extrapolation of inserting different pilot frequencies. Since the block pilot can accurately estimate the channel information on each sub-carrier within the bandwidth, it is suitable for frequency selective channels; while the comb pilot can more effectively estimate the fast time-varying channel, both have certain practical significance.
本发明的上述算例仅为详细地说明本发明的计算模型和计算流程，而并非是对本发明的实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动，这里无法对所有的实施方式予以穷举，凡是属于本发明的技术方案所引伸出的显而易见的变化或变动仍处于本发明的保护范围之列。The above calculation examples of the present invention are only to illustrate the calculation model and calculation process of the present invention in detail, but are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, on the basis of the above description, other different forms of changes or changes can also be made, and it is impossible to list all the implementations here. Obvious changes or modifications are still within the scope of the present invention.
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