Iterative frequency offset estimation method and system for wireless communication

Abstract

The invention discloses an iterative frequency offset estimation method and system for wireless communication. The method comprises the following steps: extracting a unique word signal sequence in each section of communication signal data frame; based on the unique word signal sequence, obtaining a first differential length to carry out preliminary frequency offset estimation; obtaining a second difference length for each section of communication signal after the preliminary frequency offset estimation, and carrying out the second fine frequency offset estimation; the second differential length is greater than the first differential length; for the communication signal after the second fine frequency offset estimation, calculating the average value of the unique word signal sequence of each section of the communication signal, and obtaining a third difference length to carry out third final frequency offset estimation; the third differential length is greater than the second differential length; and taking the communication signal subjected to the third-time final frequency offset estimation as a communication signal subjected to final frequency offset correction. According to the scheme, preliminary frequency offset estimation, fine frequency offset estimation and final frequency offset estimation are creatively combined, the frequency offset error range is gradually reduced, and wide-range and high-precision frequency offset estimation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to an iterative frequency offset estimation method and system for wireless communications. Background Art

[0002] High-dynamic systems such as low-orbit satellite communications and drone communications are often affected by significant Doppler frequency deviation. This frequency deviation can have many adverse effects on the communication system. First, the frequency deviation will make it difficult for the receiving end to accurately synchronize the signal of the transmitting end, affecting the symbol timing and carrier synchronization, resulting in signal synchronization difficulties. Secondly, the phase error introduced by the frequency deviation will increase the complexity of the demodulator, reduce the demodulation performance of the signal, increase the bit error rate, and reduce the demodulation performance. In addition, in a high-speed mobile environment, the rapid change of the frequency deviation will make it difficult for the system to correct in time, which may cause communication interruption and reduce the robustness of the system.

[0003] Existing frequency offset estimation algorithms often fail to meet the requirements when dealing with high-dynamic and large Doppler frequency offset variation in low-orbit satellite communication environments. This is mainly because there is a contradictory relationship between the range of frequency offset estimation and the estimation accuracy: generally speaking, the larger the estimation range, the lower the estimation accuracy. However, traditional frequency offset estimation algorithms often lead to a decrease in estimation accuracy while expanding the estimation range, and cannot meet the requirements of low-orbit satellite communications for high-precision frequency offset estimation. On the contrary, although some algorithms have higher estimation accuracy within a small frequency offset range, their estimation range is too small to cope with the large frequency offset variation in low-orbit satellite communications.

[0004] At present, frequency offset estimation and correction technology mainly includes the following methods: training sequence-based methods use known training sequences to estimate frequency offset, such as unique words (UW) and pilot signals. This method performs well in low-noise environments, but in high-dynamic and Doppler shift conditions, the training sequence length is limited, and it is difficult to guarantee the estimation range and accuracy. Blind estimation methods do not require known sequences and estimate frequency offsets through statistical characteristics or high-order statistics, such as algorithms based on cyclostationarity. This type of method has low requirements for prior information on the signal, but has slow convergence speed and high computational complexity in complex environments.

[0005] The above methods have problems such as limited estimation range, insufficient accuracy and slow response speed when dealing with high dynamic and Doppler frequency offset environments in communication systems such as low-orbit satellites. Therefore, there is an urgent need for a frequency offset estimation method that can have a wide frequency offset estimation range and maintain high estimation accuracy in a high dynamic and Doppler frequency offset environment to meet the real-time and reliability requirements of communication systems such as low-orbit satellites. Summary of the invention

[0006] In order to solve the technical problems of limited estimation range, insufficient accuracy and slow response speed in existing frequency offset estimation and correction technologies in high dynamic environments with large Doppler frequency offset changes, an embodiment of the present invention provides an iterative frequency offset estimation method and system for wireless communications.

[0007] The technical solution of the embodiment of the present invention is achieved as follows: An embodiment of the present invention provides an iterative frequency offset estimation method for wireless communication, the method comprising: Receive a communication signal and extract a unique word signal sequence in each communication signal data frame; Based on the unique word signal sequence of each communication signal segment, a first differential length is obtained, and a preliminary frequency deviation estimation is performed on each communication signal segment using the unique word signal sequence and the first differential length; For each communication signal after the preliminary frequency offset estimation, a second differential length is obtained, and a second fine frequency offset estimation is performed on the communication signal after the preliminary frequency offset estimation using the second differential length; the second differential length is greater than the first differential length; For the communication signal after the second fine frequency offset estimation, the average value of the unique word signal sequence of each communication signal segment is calculated, and a third differential length is obtained, and the third differential length is used to perform a third final frequency offset estimation on the communication signal after the second fine frequency offset estimation; the third differential length is greater than the second differential length; The communication signal with the third final frequency offset estimation is used as the communication signal for final frequency offset correction.

[0008] In one embodiment, performing preliminary frequency offset estimation includes: The communication signal is multiplied by the conjugate of the first segment of the local unique word signal sequence using the following calculation formula to obtain the demodulated signal: in, represents the signal after demodulation, represents a unique word signal sequence extracted from a communication signal data frame, , M is the length of the first segment of the unique word signal sequence; is the conjugate of the first segment of the local unique word signal sequence; Based on the demodulated signal and the first differential length, the phase difference of the delay differential when performing preliminary frequency offset estimation is calculated using the following calculation formula: in, represents the phase difference of the delay difference when making preliminary frequency offset estimation, represents the demodulated signal after delaying the first differential length, represents the conjugate of the demodulated signal at the current moment; According to the phase difference of the delay difference and the first differential length when performing the preliminary frequency offset estimation, the frequency offset of the preliminary frequency offset estimation is calculated using the following calculation formula: in, represents the frequency offset of the preliminary frequency offset estimate, represents the first difference length, is the sampling rate, M is the length of the first unique word signal sequence, Represents the phase difference of the delay differential.

[0009] In one embodiment, performing a second fine frequency offset estimation includes: The first frequency offset correction is performed on the received communication signal according to the frequency offset estimated by the preliminary frequency offset using the following calculation formula: in, is the communication signal after the first frequency offset correction, is the communication signal before the first frequency offset correction, represents the frequency offset of the preliminary frequency offset estimate, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; The communication signal after the first frequency offset correction is processed to the fourth power using the following calculation formula to eliminate the modulation effect: in, For the communication signal after quartic processing, is the communication signal after the first frequency offset correction; According to the communication signal after the fourth power processing and the second differential length, the phase difference of the delay difference when performing the second fine frequency offset estimation is calculated using the following calculation formula: in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, represents a demodulated signal after being delayed by a second differential length; represents the conjugate of the demodulated signal at the current moment; According to the phase difference of the delay difference and the second difference length when performing the second fine frequency offset estimation, the frequency offset of the second fine frequency offset estimation is calculated using the following calculation formula: in, is the frequency offset of the second fine frequency offset estimation, is the second difference length, is the sampling rate, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, N The length of the entire frame.

[0010] In one embodiment, performing a third final frequency offset estimation includes: According to the frequency offset estimated by the second fine frequency offset, the received communication signal is subjected to a second frequency offset correction using the following calculation formula to obtain a communication signal after the second frequency offset correction: in, is the communication signal after the second frequency offset correction, is the communication signal after the first frequency offset correction, is the frequency offset of the second fine frequency offset estimation, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; The unique word signal sequence is extracted using the following calculation formula: in, is the first segment of unique word signal sequence, , is the second segment unique word signal sequence, , and are the lengths of the first segment of the unique word signal sequence and the second segment of the unique word signal sequence respectively; and are the starting position of the first segment of the unique word signal sequence in the signal and the starting position of the second segment of the unique word signal sequence in the signal respectively; The extracted unique word signal sequence is multiplied by the conjugate of the local unique word signal sequence using the following calculation formula to obtain the demodulated signal: in, is the signal after the first segment of the unique word signal sequence is modulated. is the signal after the second segment unique word signal sequence is modulated. is the first segment of unique word signal sequence, is the second segment unique word signal sequence, is the conjugate of the first segment of the unique word signal sequence, is the conjugate of the second segment unique word signal sequence; The average value of the demodulated signal is calculated using the following formula: in, is the average value of the signal after the first segment of the unique word signal sequence is modulated, is the average value of the signal after the second segment unique word signal sequence is demodulated; is the signal after the first segment of the unique word signal sequence is modulated. is the signal after the second segment unique word signal sequence is modulated. , , and are the lengths of the first segment of the unique word signal sequence and the second segment of the unique word signal sequence respectively; The phase difference of the average value product is calculated according to the average value of the demodulated signal using the following calculation formula: in, is the phase difference of the product of the average values, is the average value of the signal after the first segment of the unique word signal sequence is modulated, is the average value of the signal after the second segment unique word signal sequence is demodulated; The final frequency deviation is calculated using the following formula based on the phase difference of the average product: in, is the final frequency deviation, is the phase difference of the product of the average values, is the third difference length, is the sampling rate.

[0011] In one embodiment, the first differential length is set to 16 when the symbol rate is 16k.

[0012] In one embodiment, the second differential length is set to 64 when the symbol rate is 16k.

[0013] In one embodiment, the third differential length is set to 160 according to the frame structure of the communication signal.

[0014] An embodiment of the present invention further provides an iterative frequency offset estimation system for wireless communications, comprising: a processor and a memory for storing a computer program that can be run on the processor; wherein the processor executes the steps of the above-mentioned method when running the computer program.

[0015] The embodiments of the present invention have the following beneficial effects: This embodiment adopts a three-stage iterative estimation strategy, and adopts a three-stage frequency offset estimation method from coarse to fine. Each stage uses the estimation results of the previous stage for further correction and refinement. Through iteration, the frequency offset error is gradually reduced, and the initial large error range is converged to a very small error range. This method of combining preliminary frequency offset estimation, fine frequency offset estimation and final frequency offset estimation can gradually reduce the frequency offset error range and realize wide-range and high-precision frequency offset estimation.

[0016] In addition, the first differential length, the second differential length and the third differential length in this embodiment can be flexibly set according to signal characteristics and system requirements, taking into account both the estimation range and accuracy.

[0017] In addition, while taking into account the estimation range and accuracy, the average value of multiple unique word signal sequences is used to enhance the signal's noise resistance and significantly improve the accuracy and stability of frequency offset estimation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a flow chart of an iterative frequency offset estimation method for wireless communication according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the system flow of an embodiment of the present invention; Figure 3 This is a schematic diagram of a frame structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the first frequency offset estimation error distribution according to an embodiment of the present invention; Figure 5 A schematic diagram of the second frequency offset estimation error distribution according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the third frequency offset estimation error distribution according to an embodiment of the present invention; Figure 7 1 is a diagram showing the internal structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0020] The embodiment of the present invention provides an iterative frequency offset estimation method for wireless communication, such as Figure 1 As shown, the method includes: Step 101: receiving a communication signal and extracting a unique word signal sequence in each communication signal data frame; Step 102: obtaining a first differential length based on a unique word signal sequence of each communication signal segment, and performing a preliminary frequency offset estimation on each communication signal segment using the unique word signal sequence and the first differential length; Step 103: for each communication signal after the preliminary frequency offset estimation, obtain a second differential length, and use the second differential length to perform a second fine frequency offset estimation on the communication signal after the preliminary frequency offset estimation; the second differential length is greater than the first differential length; Step 104: for the communication signal after the second fine frequency offset estimation, the average value of the unique word signal sequence of each communication signal segment is calculated, and a third differential length is obtained, and the third final frequency offset estimation is performed on the communication signal after the second fine frequency offset estimation using the average value of the unique word signal sequence of each communication signal segment and the third differential length; the third differential length is greater than the second differential length; Step 105: Using the communication signal with the third final frequency offset estimation as the communication signal for final frequency offset correction.

[0021] This embodiment is applicable to communication systems with high dynamics and large Doppler frequency deviation changes, such as low-orbit satellite communication, drone communication, etc., such as drone communication, high-speed mobile communication, aviation communication and high-speed maritime communication.

[0022] (1) UAV communication system. When a UAV is performing a high-speed flight mission, the communication link between the UAV and the ground control station will be affected by the Doppler frequency deviation. The method of this embodiment can improve the stability of the communication link and the reliability of data transmission.

[0023] (2) High-speed mobile communication system. When a high-speed train is running, the communication with the base stations along the line is affected by frequency deviation. The method of this embodiment can improve the anti-interference ability and communication quality of the train and ground communication system.

[0024] (3) Aviation communication system. When an aircraft is flying at high speed, the communication between the aircraft and the ground or satellite needs to overcome the influence of Doppler frequency deviation. The method of this embodiment can be used to improve the reliability of the communication link and ensure flight safety.

[0025] (4) High-speed marine communication system. The communication between a high-speed ship and a satellite or ground station will also be affected by frequency deviation. The method of this embodiment can be applied to marine communication to improve signal quality.

[0026] That is, due to the high-speed movement of the above system, its communication signal is often affected by the significant Doppler effect, resulting in frequency offset. The method of this embodiment can quickly and accurately estimate and correct the frequency offset, ensuring the accuracy of signal processing and the reliability of communication.

[0027] The core of the scheme of this embodiment is to use a three-stage iterative processing method to gradually reduce the estimation error of the frequency offset. In the first stage, this embodiment uses the unique word signal sequence (i.e., UW) in the received downsampled signal for preliminary frequency offset estimation. UW refers to a known signal sequence used for synchronization and frequency offset estimation, which is usually inserted into the data frame of the communication signal to serve as a reference. The UW signal can not only improve the estimation accuracy, but also enhance the robustness of the system in a Doppler frequency offset environment, reducing the frequency offset error range to within 100Hz. In the second stage, all signals after the first correction are used for more accurate frequency offset estimation, further reducing the error to 60Hz. In the third stage, the average value of multiple segments of UW is used for the final frequency offset estimation, reducing the error range to within 10Hz.

[0028] Below, the solution of this embodiment will be described in detail based on a specific application scenario.

[0029] See also Figure 2 , the method of this embodiment mainly includes the following steps: the first stage, preliminary frequency offset estimation: extract the first segment of unique words from the received data according to the frame structure, set an appropriate differential length, calculate the phase difference of the delayed differential, preliminarily estimate the frequency offset, and reduce the frequency offset error range to within 100Hz. The second stage, fine frequency offset estimation: use the entire signal of one frame after the first frequency offset correction to perform blind frequency offset estimation, and further reduce the error to within 60Hz. The third stage, final frequency offset estimation: use the average value of multiple segments of unique words, increase the differential length, improve the estimation accuracy, and reduce the error range to within 10Hz.

[0030] The following will introduce the above three stages in detail.

[0031] The first stage of this embodiment is preliminary frequency offset estimation. Figure 3 The frame structure shown in the figure extracts the UW signal sequence in the first communication signal. ,in , M is the length of the first UW signal sequence.

[0032] Then, the conjugate of the received first UW signal sequence and the locally stored first UW signal sequence is calculated using the following formula: Multiply them together to get the demodulated signal : in, represents the signal after demodulation, Represents the first segment of unique word signal sequence extracted from the communication signal data frame, , M is the length of the first segment of the unique word signal sequence; is the conjugate of the first segment of local UW; Then, calculate the phase difference of the delay difference : in, represents the phase difference of the delay difference when making preliminary frequency offset estimation, Indicates the delay first differential length After the demodulation signal, represents the conjugate of the demodulated signal at the current moment; Finally, estimate the initial frequency offset : in, represents the frequency offset of the preliminary frequency offset estimate, represents the first difference length, is the sampling rate, M is the length of the first unique word, Represents the phase difference of the delay differential.

[0033] This step can reduce the frequency offset error range to within 100 Hz, providing a good initial condition for subsequent fine estimation. In addition, by multiplying the UW signal sequence with the conjugate of the local UW signal, the modulation information can be effectively removed and the frequency offset information can be retained, which is convenient for subsequent frequency offset estimation.

[0034] The second stage of this embodiment is fine frequency offset estimation. For receiving signal To perform frequency offset correction: in, is the communication signal after the first frequency offset correction, is the communication signal before the first frequency offset correction, represents the frequency offset of the preliminary frequency offset estimate, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; The corrected signal is then processed to the fourth power to remove the modulation effect: in, For the communication signal after quartic processing, It is the communication signal after the first frequency offset correction.

[0035] Then calculate the phase difference of the delay difference : in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, Delayed second differential length The de-modulated signal afterwards; represents the conjugate of the demodulated signal at the current moment; Then estimate the fine frequency deviation : in, is the frequency offset of the second fine frequency offset estimation, is the second difference length, is the sampling rate, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, N The length of the entire frame.

[0036] Since the signal is processed to the fourth power, the frequency deviation is amplified by 4 times, so when estimating the frequency deviation, it is necessary to divide by This step further reduces the frequency offset error to within 60 Hz and corrects most of the frequency offset residual.

[0037] The third stage of this embodiment is the final frequency offset estimation. Perform frequency deviation correction on the received signal again to obtain the signal after secondary correction : in, is the communication signal after the second frequency offset correction, is the communication signal after the first frequency offset correction, is the frequency offset of the second fine frequency offset estimation, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; Extract the first and second segments of the received UW signal and : Among them, the first UW signal: , the second section of UW signal: , and The lengths of the first and second segments of UW may not be equal. and are the starting positions of the first and second segments UW in the signal respectively.

[0038] The extracted UW signal is multiplied by the conjugate of the locally stored UW signal to obtain the demodulated signal: in, and is the local UW signal of corresponding length.

[0039] Calculate the average value of two UW signals and : Calculate the phase difference of the product of the averages : Estimation of final frequency deviation : in, is the third differential length, i.e., the distance between the starting positions of the two UW segments.

[0040] This step can ultimately reduce the frequency offset error to within 10 Hz, achieving high-precision frequency offset estimation.

[0041] The method of this embodiment adopts an iterative processing method to gradually reduce the frequency offset error range and can quickly estimate the frequency offset. By increasing the difference length and using the average value of multiple unique words, the accuracy of frequency offset estimation is significantly improved. It is suitable for communication environments such as low-orbit satellites with high dynamics and large Doppler shift changes, and has strong adaptability.

[0042] Also, see Figure 4-Figure 6 , Figure 4-Figure 6 They are respectively a schematic diagram of the first frequency offset estimation error distribution according to an embodiment of the present invention, a schematic diagram of the second frequency offset estimation error distribution according to an embodiment of the present invention, and a schematic diagram of the third frequency offset estimation error distribution according to an embodiment of the present invention. Figure 4-Figure 6 It can be seen that the solution of this embodiment can achieve high-precision frequency offset estimation within a wide frequency offset range, improve the reliability and stability of the communication system, and has important application value and broad application prospects.

[0043] In addition, it should be noted that the first differential length in this embodiment is , the second differential length and the third difference length In different communication systems, adjustments can be made according to specific frequency offset ranges, signal characteristics, and system requirements to achieve optimal frequency offset estimation performance.

[0044] This embodiment can perform effective estimation within a larger frequency deviation range (such as hundreds to thousands of hertz) in the preliminary estimation stage, providing a reliable initial value for subsequent fine estimation. The error range in the final estimation stage can be reduced to within 10 Hz, meeting the requirements of low-orbit satellite communications for high-precision frequency deviation estimation. The iterative method has a fast convergence speed and low computational complexity at each stage, which is suitable for real-time processing needs. In addition, this method is suitable for various high-dynamic communication environments with large Doppler frequency shift changes, including low-orbit satellite communications, drone communications, and high-speed mobile communications, and has broad application prospects.

[0045] In order to implement the method of an embodiment of the present invention, an embodiment of the present invention also provides an iterative frequency offset estimation system for wireless communication, including: a processor and a memory for storing a computer program that can be run on the processor; wherein, when the processor is used to run the computer program, the steps of the above-mentioned method are executed.

[0046] The above-mentioned system provided in this embodiment belongs to the same concept as the above-mentioned method embodiment. The specific implementation process thereof is detailed in the method embodiment and will not be repeated here.

[0047] In order to implement the method of the embodiment of the present invention, the embodiment of the present invention also provides a computer program product, which includes computer instructions, and the computer instructions are stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps of the above method.

[0048] Based on the hardware implementation of the above program modules, and in order to implement the method of the embodiment of the present invention, the embodiment of the present invention further provides an electronic device (computer device). Specifically, in one embodiment, the computer device may be a terminal, and its internal structure diagram may be as follows: Figure 7As shown. The computer device includes a processor A01, a network interface A02, a display screen A04, an input device A05 and a memory (not shown in the figure) connected through a system bus. Among them, the processor A01 of the computer device is used to provide computing and control capabilities. The memory of the computer device includes an internal memory A03 and a non-volatile storage medium A06. The non-volatile storage medium A06 stores an operating system B01 and a computer program B02. The internal memory A03 provides an environment for the operation of the operating system B01 and the computer program B02 in the non-volatile storage medium A06. The network interface A02 of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor A01, the method of any one of the above embodiments is implemented. The display screen A04 of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device A05 of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0049] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0050] The device provided by the embodiment of the present invention includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, the method of any one of the above embodiments is implemented.

[0051] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0052] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0053] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0054] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0055] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0056] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0057] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0058] It can be understood that the memory of the embodiment of the present invention can be a volatile memory or a non-volatile memory, and can also include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM); the magnetic surface memory can be a disk memory or a tape memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), synchronous static random access memory (SSRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM, SyncLink Dynamic Random Access Memory), and direct RAMbus random access memory (DRRAM, Direct Rambus Random Access Memory).The memories described in the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memories.

[0059] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0060] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for iterative frequency offset estimation for wireless communication, characterized in that: The method comprises: Receive a communication signal and extract a unique word signal sequence in each communication signal data frame; Based on the unique word signal sequence of each communication signal segment, a first differential length is obtained, and a preliminary frequency deviation estimation is performed on each communication signal segment using the unique word signal sequence and the first differential length; For each communication signal after the preliminary frequency offset estimation, a second differential length is obtained, and a second fine frequency offset estimation is performed on the communication signal after the preliminary frequency offset estimation using the second differential length; the second differential length is greater than the first differential length; For the communication signal after the second fine frequency offset estimation, the average value of the unique word signal sequence of each communication signal segment is calculated, and a third differential length is obtained, and the third differential length is used to perform a third final frequency offset estimation on the communication signal after the second fine frequency offset estimation; the third differential length is greater than the second differential length; The communication signal with the third final frequency offset estimation is used as the communication signal for final frequency offset correction.

2. The iterative frequency offset estimation method for wireless communication according to claim 1, characterized in that: Perform a preliminary frequency offset estimate, including: The communication signal is multiplied by the conjugate of the first segment of the local unique word signal sequence using the following calculation formula to obtain the demodulated signal: ； in, represents the signal after demodulation, represents a unique word signal sequence extracted from a communication signal data frame, , M is the length of the first segment of the unique word signal sequence; is the conjugate of the first segment of the local unique word signal sequence; Based on the demodulated signal and the first differential length, the phase difference of the delay differential when performing preliminary frequency offset estimation is calculated using the following calculation formula: ； in, represents the phase difference of the delay difference when making preliminary frequency offset estimation, represents the demodulated signal after delaying the first differential length, represents the conjugate of the demodulated signal at the current moment; According to the phase difference of the delay difference and the first differential length when performing the preliminary frequency offset estimation, the frequency offset of the preliminary frequency offset estimation is calculated using the following calculation formula: ； in, represents the frequency offset of the preliminary frequency offset estimate, represents the first difference length, is the sampling rate, M is the length of the first unique word signal sequence, Represents the phase difference of the delay differential.

3. The iterative frequency offset estimation method for wireless communication according to claim 1, characterized in that: Perform the second fine frequency offset estimation, including: The first frequency offset correction is performed on the received communication signal according to the frequency offset estimated by the preliminary frequency offset using the following calculation formula: ； in, is the communication signal after the first frequency offset correction, is the communication signal before the first frequency offset correction, represents the frequency offset of the preliminary frequency offset estimate, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; The communication signal after the first frequency offset correction is processed to the fourth power using the following calculation formula to eliminate the modulation effect: ； in, For the communication signal after quartic processing, is the communication signal after the first frequency offset correction; According to the communication signal after the fourth power processing and the second differential length, the phase difference of the delay difference when performing the second fine frequency offset estimation is calculated using the following calculation formula: ； in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, represents a demodulated signal after being delayed by a second differential length; represents the conjugate of the demodulated signal at the current moment; According to the phase difference of the delay difference and the second difference length when performing the second fine frequency offset estimation, the frequency offset of the second fine frequency offset estimation is calculated using the following calculation formula: ； in, is the frequency offset of the second fine frequency offset estimation, is the second difference length, is the sampling rate, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, N The length of the entire frame.

4. The iterative frequency offset estimation method for wireless communication according to claim 1, characterized in that: Perform the third final frequency offset estimation, including: According to the frequency offset estimated by the second fine frequency offset, the received communication signal is subjected to a second frequency offset correction using the following calculation formula to obtain a communication signal after the second frequency offset correction: ； in, is the communication signal after the second frequency offset correction, is the communication signal after the first frequency offset correction, is the frequency offset of the second fine frequency offset estimation, is the sampling rate, , N is the length of the whole frame, j is the imaginary unit; The unique word signal sequence is extracted using the following calculation formula: ； ； in, is the first segment of unique word signal sequence, , is the second segment unique word signal sequence, , and are the lengths of the first segment of the unique word signal sequence and the second segment of the unique word signal sequence respectively; and are the starting position of the first segment of the unique word signal sequence in the signal and the starting position of the second segment of the unique word signal sequence in the signal respectively; The extracted unique word signal sequence is multiplied by the conjugate of the local unique word signal sequence using the following calculation formula to obtain the demodulated signal: ； ； in, is the signal after the first segment of the unique word signal sequence is modulated. is the signal after the second segment unique word signal sequence is modulated. is the first segment of unique word signal sequence, is the second segment unique word signal sequence, is the conjugate of the first segment of the unique word signal sequence, is the conjugate of the second segment unique word signal sequence; The average value of the demodulated signal is calculated using the following formula: ； ； in, is the average value of the signal after the first segment of the unique word signal sequence is modulated, is the average value of the signal after the second segment unique word signal sequence is demodulated; is the signal after the first segment of the unique word signal sequence is modulated. is the signal after the second segment unique word signal sequence is modulated. , , and are the lengths of the first segment of the unique word signal sequence and the second segment of the unique word signal sequence respectively; The phase difference of the average value product is calculated according to the average value of the demodulated signal using the following calculation formula: ； in, is the phase difference of the product of the average values, is the average value of the signal after the first segment of the unique word signal sequence is modulated, is the average value of the signal after the second segment unique word signal sequence is demodulated; The final frequency deviation is calculated using the following formula based on the phase difference of the average product: ； in, is the final frequency deviation, is the phase difference of the product of the average values, is the third difference length, is the sampling rate.

5. The iterative frequency offset estimation method for wireless communication according to claim 1, characterized in that: The first differential length is set to 16 when the symbol rate is 16k.

6. The iterative frequency offset estimation method for wireless communication according to claim 1, characterized in that: The second differential length is set to 64 when the symbol rate is 16k.

7. The iterative frequency offset estimation method for wireless communication according to claim 3, characterized in that: The third differential length is set to 160 according to the frame structure of the communication signal.

8. An iterative frequency offset estimation system for wireless communication, characterized in that: include: A processor and a memory for storing a computer program that can be run on the processor; wherein, when the processor is used to run the computer program, the steps of the method according to any one of claims 1 to 7 are executed.

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