Iterative frequency offset estimation method and system for wireless communication

Abstract

The present invention discloses an iterative frequency offset estimation method and system for wireless communication. The method includes extracting a unique word signal sequence in each communication signal data frame; based on the unique word signal sequence, obtaining a first differential length to perform a preliminary frequency offset estimation; for each communication signal after the preliminary frequency offset estimation, obtaining a second differential length to perform a 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 communication signal, and obtaining a third differential length to perform a third final frequency offset estimation; the third differential length is greater than the second differential length; the communication signal of the third final frequency offset estimation is used as the communication signal for the final frequency offset correction. The solution of the present invention innovatively combines preliminary frequency offset estimation, fine frequency offset estimation and final frequency offset estimation, gradually narrowing the frequency offset error range, and realizing wide-range, high-precision frequency offset estimation.

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] Highly dynamic systems, such as low-orbit satellite communications and drone communications, are often subject to significant Doppler frequency offset. This frequency offset can adversely affect communication systems in several ways. First, frequency offset makes it difficult for the receiver to accurately synchronize with the transmitter's signal, affecting symbol timing and carrier synchronization, making signal synchronization difficult. Second, the phase error introduced by frequency offset increases demodulator complexity, reduces signal demodulation performance, and increases the bit error rate, resulting in reduced demodulation performance. Furthermore, in high-speed mobile environments, rapid changes in frequency offset make it difficult for the system to correct for these changes in a timely manner, potentially leading to communication interruptions and reduced system robustness.

[0003] Existing frequency offset estimation algorithms often struggle to meet the demands of low-orbit satellite communications environments characterized by high dynamics and large Doppler frequency offset variations. This is primarily due to the conflicting relationship between the frequency offset estimation range and accuracy: generally speaking, the larger the estimation range, the lower the estimation accuracy. However, traditional frequency offset estimation algorithms often suffer from reduced accuracy when expanding the estimation range, failing to meet the high-precision frequency offset estimation requirements of low-orbit satellite communications. Conversely, some algorithms, while achieving high estimation accuracy within a small frequency offset range, have an estimation range that is too narrow to handle the large frequency offset variations found in low-orbit satellite communications.

[0004] Currently, frequency offset estimation and correction technologies primarily fall into the following categories: Training sequence-based methods utilize known training sequences, such as unique words (UWs) and pilot signals, for frequency offset estimation. These methods offer good performance in low-noise environments. However, in high-dynamic environments with large Doppler shift variations, the limited length of the training sequence makes it difficult to guarantee estimation range and accuracy. Blind estimation methods, such as those based on cyclostationarity, do not require a known sequence and instead estimate frequency offset based on statistical properties or higher-order statistics. These methods require less prior information about the signal, but they converge slowly and have high computational complexity in complex environments.

[0005] The aforementioned methods suffer from limited estimation range, insufficient accuracy, and slow response when dealing with the highly dynamic and Doppler-shifted environments found in communication systems such as low-orbit satellites. Therefore, a frequency offset estimation method that can maintain a wide frequency offset estimation range and high accuracy in highly dynamic and Doppler-shifted environments is urgently needed to meet the real-time and reliability requirements of communication systems such as low-orbit satellites. Summary of the Invention

[0006] To address the technical problems of limited estimation range, insufficient accuracy and slow response speed in existing frequency offset estimation and correction technologies in highly dynamic environments with large Doppler frequency offset variations, 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:

[0008] An embodiment of the present invention provides an iterative frequency offset estimation method for wireless communication, the method comprising:

[0009] Receive a communication signal and extract a unique word signal sequence in each communication signal data frame;

[0010] 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;

[0011] For each segment of the communication signal after the preliminary frequency offset estimation, obtaining a second differential length, and performing a second fine frequency offset estimation 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;

[0012] For the communication signal after the second fine frequency offset estimation, calculating an average value of the unique word signal sequence of each segment of the communication signal, and obtaining a third differential length, and performing a third final frequency offset estimation on the communication signal after the second fine frequency offset estimation using the average value of the unique word signal sequence of each segment of the communication signal and the third differential length; the third differential length is greater than the second differential length;

[0013] The communication signal obtained by the third final frequency offset estimation is used as the communication signal for final frequency offset correction.

[0014] In one embodiment, performing preliminary frequency offset estimation includes:

[0015] The communication signal is multiplied by the conjugate of the first segment of the local unique word signal sequence using the following formula to obtain the demodulated signal:

[0016]

[0017] in, represents the demodulated signal, 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;

[0018] 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 formula:

[0019]

[0020] in, represents the phase difference of the delay difference when performing 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;

[0021] 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:

[0022]

[0023] 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 segment of the unique word signal sequence, Indicates the phase difference of the delay differential.

[0024] In one embodiment, performing a second fine frequency offset estimation includes:

[0025] The first frequency offset correction is performed on the received communication signal using the following formula based on the frequency offset estimated by the preliminary frequency offset:

[0026]

[0027] 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;

[0028] Use the following formula to perform fourth-order processing on the communication signal after the first frequency offset correction to eliminate the modulation effect:

[0029]

[0030] in, For communication signals after quartic processing, is the communication signal after the first frequency offset correction;

[0031] Based on the communication signal after quartic processing and the second differential length, the phase difference of the delay differential when performing the second fine frequency offset estimation is calculated using the following formula:

[0032]

[0033] in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, represents the demodulated signal after being delayed by the second differential length; represents the conjugate of the demodulated signal at the current moment;

[0034] According to the phase difference and the second differential length of the delay difference 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:

[0035]

[0036] in, is the frequency offset of the second fine frequency offset estimation, is the second differential 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.

[0037] In one embodiment, performing a third final frequency offset estimation includes:

[0038] The received communication signal is subjected to a second frequency offset correction using the following formula based on the frequency offset estimated by the second fine frequency offset, thereby obtaining a communication signal after the second frequency offset correction:

[0039]

[0040] 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;

[0041] The unique word signal sequence is extracted using the following calculation formula:

[0042]

[0043]

[0044] 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 positions of the first segment of the unique word signal sequence and the second segment of the unique word signal sequence in the signal respectively;

[0045] The extracted unique word signal sequence is multiplied by the conjugate of the local unique word signal sequence using the following formula to obtain the demodulated signal:

[0046]

[0047]

[0048] in, is the signal after the first segment of the unique word signal sequence is demodulated. is the signal after the second segment unique word signal sequence is demodulated. 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 of the unique word signal sequence;

[0049] The average value of the demodulated signal is calculated using the following formula:

[0050]

[0051]

[0052] 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 demodulation of the second segment unique word signal sequence; is the signal after the first segment of the unique word signal sequence is demodulated. is the signal after the second segment unique word signal sequence is demodulated. , , 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;

[0053] The phase difference of the average value product is calculated based on the average value of the demodulated signal using the following formula:

[0054]

[0055] 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 demodulation of the second segment unique word signal sequence;

[0056] The final frequency deviation is calculated using the following formula based on the phase difference of the average product:

[0057]

[0058] in, is the final frequency deviation, is the phase difference of the product of the average values, is the third differential length, is the sampling rate.

[0059] In one embodiment, the first differential length is set to 16 when the symbol rate is 16k.

[0060] In one embodiment, the second differential length is set to 64 when the symbol rate is 16k.

[0061] In one embodiment, the third differential length is set to 160 according to the frame structure of the communication signal.

[0062] 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-described method when running the computer program.

[0063] The embodiments of the present invention have the following beneficial effects:

[0064] This embodiment employs a three-stage iterative estimation strategy, employing a coarse-to-fine frequency offset estimation method. Each stage utilizes the estimation results from the previous stage for further correction and refinement. This iterative approach gradually reduces the frequency offset error, achieving convergence from an initially large error range to an extremely small error range. This combination of preliminary frequency offset estimation, refined frequency offset estimation, and final frequency offset estimation gradually reduces the frequency offset error range, achieving wide-range, high-precision frequency offset estimation.

[0065] 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 both estimation range and accuracy into consideration.

[0066] 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

[0067] Figure 1 Schematic diagram of a flow chart of an iterative frequency offset estimation method for wireless communication according to an embodiment of the present invention;

[0068] Figure 2 This is a schematic diagram of the system flow of an embodiment of the present invention;

[0069] Figure 3 This is a schematic diagram of the frame structure of an embodiment of the present invention;

[0070] Figure 4 This is a schematic diagram of the first frequency offset estimation error distribution according to an embodiment of the present invention;

[0071] Figure 5 Schematic diagram of the second frequency offset estimation error distribution according to an embodiment of the present invention;

[0072] Figure 6 This is a schematic diagram of the third frequency offset estimation error distribution according to an embodiment of the present invention;

[0073] Figure 7 This is a diagram of the internal structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0075] 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:

[0076] Step 101: receiving a communication signal and extracting a unique word signal sequence in each communication signal data frame;

[0077] 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;

[0078] Step 103: Obtain a second differential length for each communication signal after the preliminary frequency offset estimation, and perform a second fine frequency offset estimation 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;

[0079] Step 104: For the communication signal after the second fine frequency offset estimation, calculate the average value of the unique word signal sequence of each communication signal segment, and obtain a third differential length, and perform a third final frequency offset estimation 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;

[0080] Step 105: The communication signal resulting from the third final frequency offset estimation is used as the communication signal for final frequency offset correction.

[0081] This embodiment is applicable to communication systems with high dynamics and large Doppler frequency deviation variations, such as low-orbit satellite communication, drone communication, high-speed mobile communication, aviation communication, and high-speed maritime communication.

[0082] (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 Doppler frequency deviation. The method of this embodiment can improve the stability of the communication link and the reliability of data transmission.

[0083] (2) High-speed mobile communication system. When a high-speed train is traveling, its communication with base stations along the line is affected by frequency deviation. The method of this embodiment can improve the anti-interference capability and communication quality between the train and the ground communication system.

[0084] (3) Aviation communication systems. When an aircraft is flying at high speed, communications with the ground or satellites must overcome the effects of Doppler frequency offset. The method of this embodiment can be used to improve the reliability of the communication link and ensure flight safety.

[0085] (4) High-speed maritime communication systems. Communications between high-speed ships and satellites or ground stations are also affected by frequency deviation. The method of this embodiment can be applied to maritime communications to improve signal quality.

[0086] That is, due to the high-speed movement of the above-mentioned system, its communication signals are 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.

[0087] The core of the solution of this embodiment is to adopt 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 down-sampled signal to perform 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, and reduce the frequency offset error range to within 100Hz. In the second stage, all signals after the first correction are used to perform more accurate frequency offset estimation, and the error is further reduced to 60Hz. In the third stage, the average value of multiple segments of UW is used for the final frequency offset estimation, and the error range is reduced to within 10Hz.

[0088] Below, the solution of this embodiment will be described in detail based on a specific application scenario.

[0089] 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 the appropriate differential length, calculate the phase difference of the delayed differential, preliminarily estimate the frequency offset, and narrow 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 narrow 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 narrow the error range to within 10Hz.

[0090] The following will introduce the above three stages in detail.

[0091] The first stage of this embodiment is the 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.

[0092] Then, the conjugate of the received first segment UW signal sequence and the locally stored first segment UW signal is calculated using the following formula: Multiply to get the demodulated signal :

[0093]

[0094] in, represents the demodulated signal, Represents the first segment of unique word signal sequence extracted from the communication signal data frame, , Mis the length of the first segment of the unique word signal sequence; is the conjugate of the first local UW segment;

[0095] Then, calculate the phase difference of the delay difference :

[0096]

[0097] in, represents the phase difference of the delay difference when performing preliminary frequency offset estimation, Indicates the first differential length of the delay After the demodulated signal, represents the conjugate of the demodulated signal at the current moment;

[0098] Finally, estimate the preliminary frequency offset :

[0099]

[0100] 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, Indicates the phase difference of the delay differential.

[0101] This step can reduce the frequency offset error to within 100 Hz, providing a good initial condition for subsequent fine-grained estimation. Furthermore, by multiplying the UW signal sequence with the conjugate of the local UW signal, the modulation information can be effectively removed while retaining the frequency offset information, facilitating subsequent frequency offset estimation.

[0102] The second stage of this embodiment is fine frequency offset estimation. To receive the signal Perform frequency offset correction:

[0103]

[0104] 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;

[0105] The corrected signal is then processed to the fourth power to remove the modulation effect:

[0106]

[0107] in, For communication signals after quartic processing, is the communication signal after the first frequency offset correction.

[0108] Then calculate the phase difference of the delay difference :

[0109]

[0110] in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, Indicates the delayed second differential length The demodulated signal afterwards; represents the conjugate of the demodulated signal at the current moment;

[0111] Then estimate the fine frequency offset :

[0112]

[0113] in, is the frequency offset of the second fine frequency offset estimation, is the second differential 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.

[0114] 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.

[0115] The third stage of this embodiment is the final frequency offset estimation. Perform frequency deviation correction on the received signal again to obtain the second-corrected signal :

[0116]

[0117] 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;

[0118] Extract the first and second segments of the received UW signal and :

[0119]

[0120]

[0121] Among them, the first UW signal: , the second section of UW signal: , and The lengths of the first and second segments of UW may be unequal. and are the starting positions of the first and second segments UW in the signal respectively.

[0122] Multiply the extracted UW signal with the conjugate of the locally stored UW signal to obtain the demodulated signal:

[0123]

[0124]

[0125] in, and is the local UW signal of corresponding length.

[0126] Calculate the average value of two UW signals and :

[0127]

[0128]

[0129] Calculate the phase difference of the product of the average values :

[0130]

[0131] Estimated final frequency offset :

[0132]

[0133] in, is the third differential length, that is, the distance between the starting positions of the two UW segments.

[0134] This step can ultimately reduce the frequency offset error to within 10 Hz, achieving high-precision frequency offset estimation.

[0135] This embodiment's method uses an iterative process to gradually narrow the frequency offset error range, enabling rapid frequency offset estimation. By increasing the differential length and utilizing the average value of multiple unique words, the accuracy of frequency offset estimation is significantly improved. It is highly adaptable to communication environments such as low-orbit satellites with high dynamics and large Doppler shift variations.

[0136] 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.

[0137] In addition, it should be noted that the first differential length in this embodiment is , the second differential length and the third differential 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.

[0138] This embodiment can effectively estimate frequency offsets within a wide frequency range (e.g., hundreds to thousands of hertz) during the preliminary estimation phase, providing a reliable initial value for subsequent refined estimation. The error range in the final estimation phase can be reduced to less than 10 Hz, meeting the high-precision frequency offset estimation requirements of low-orbit satellite communications. The iterative method offers rapid convergence and low computational complexity at each stage, making it suitable for real-time processing. Furthermore, this method is applicable to a variety of highly dynamic communication environments with large Doppler shift variations, including low-orbit satellite communications, drone communications, and high-speed mobile communications, and has broad application prospects.

[0139] 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, it executes the steps of the above-mentioned method.

[0140] The above-mentioned system provided in this embodiment and the above-mentioned method embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0141] To implement the method of an embodiment of the present invention, an embodiment of the present invention further provides a computer program product. The computer program product includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps of the above method.

[0142] 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 can be a terminal, and its internal structure diagram can be as follows: Figure 7 As 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 via a system bus. 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 via a network connection. When the computer program is executed by the processor A01, the method of any of the above embodiments is implemented. The display screen A04 of the computer device can be a liquid crystal display or an electronic ink display. The input device A05 of the computer device can be a touch layer covering the display screen, or it can be a key, trackball, or touchpad provided on the computer device housing, or it can be an external keyboard, touchpad, or mouse.

[0143] 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 shown in the figure, or combine certain components, or have a different component arrangement.

[0144] The device provided by an 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.

[0145] 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 take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0146] 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 block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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 produce 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.

[0147] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work 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 The function specified in one or more boxes.

[0148] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0149] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0150] 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.

[0151] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The 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 disc read-only memory (CD-ROM), digital versatile disc (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 transitory computer-readable media (transitory media), such as modulated data signals and carrier waves.

[0152] It is understood that the memory of the embodiments of the present invention may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Among them, non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), ferromagnetic random access memory (FRAM), flash memory, magnetic surface memory, optical disk, or compact disc read-only memory (CD-ROM); magnetic surface memory may be magnetic disk or tape memory. Volatile memory may be 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), and direct rambus random access memory (DRRAM).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.

[0153] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0154] The above are merely 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 modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A method for iterative frequency offset estimation in 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; 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; For each segment of the communication signal after the preliminary frequency offset estimation, obtaining a second differential length, and performing a second fine frequency offset estimation 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, calculating an average value of the unique word signal sequence of each segment of the communication signal, and obtaining a third differential length, and performing a third final frequency offset estimation on the communication signal after the second fine frequency offset estimation using the average value of the unique word signal sequence of each segment of the communication signal and the third differential length; the third differential length is greater than the second differential length; The communication signal obtained by 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, wherein: Perform preliminary frequency offset estimation, including: The communication signal is multiplied by the conjugate of the first segment of the local unique word signal sequence using the following formula to obtain the demodulated signal: ； in, represents the demodulated signal, 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 formula: ； in, represents the phase difference of the delay difference when performing 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 segment of the unique word signal sequence, Indicates the phase difference of the delay differential.

3. The iterative frequency offset estimation method for wireless communication according to claim 1, wherein: Perform the second fine frequency offset estimation, including: The first frequency offset correction is performed on the received communication signal using the following formula based on the frequency offset estimated by the preliminary frequency offset: ； 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; Use the following formula to perform fourth-order processing on the communication signal after the first frequency offset correction to eliminate the modulation effect: ； in, For communication signals after quartic processing, is the communication signal after the first frequency offset correction; Based on the communication signal after quartic processing and the second differential length, the phase difference of the delay differential when performing the second fine frequency offset estimation is calculated using the following formula: ； in, represents the phase difference of the delay difference when performing the second fine frequency offset estimation, represents the demodulated signal after being delayed by the second differential length; represents the conjugate of the demodulated signal at the current moment; According to the phase difference and the second differential length of the delay difference 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 differential 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, wherein: Perform the third final frequency offset estimation, including: The received communication signal is subjected to a second frequency offset correction using the following formula based on the frequency offset estimated by the second fine frequency offset, thereby obtaining 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 positions of the first segment of the unique word signal sequence and 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 formula to obtain the demodulated signal: ； ； in, is the signal after the first segment of the unique word signal sequence is demodulated. is the signal after the second segment unique word signal sequence is demodulated. 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 of the 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 demodulation of the second segment unique word signal sequence; is the signal after the first segment of the unique word signal sequence is demodulated. is the signal after the second segment unique word signal sequence is demodulated. , , 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 based on the average value of the demodulated signal using the following 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 demodulation of the second segment unique word signal sequence; 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 differential length, is the sampling rate.

5. The iterative frequency offset estimation method for wireless communication according to claim 1, wherein: 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, wherein: 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, wherein: 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 performed.

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