Wireless continuous communication synchronization method and system based on time-frequency joint feedback correction

Abstract

This invention discloses a wireless continuous communication synchronization method and system based on time-frequency joint feedback correction. The method includes: a slave device calculating a carrier frequency offset estimate and a timing estimate L of the received signal using a preamble sequence; calculating a remaining carrier frequency offset estimate and a remaining timing offset estimate using an auxiliary pilot; and the slave device locating the starting point of the data stream based on the timing estimate L. The slave device then feeds back the carrier frequency offset estimate ΔF, the remaining carrier frequency offset estimate, and the remaining timing offset estimate to a global synchronization controller. This invention's wireless continuous communication synchronization method and system utilizes the timing estimate L estimated by the time-domain preamble sequence to locate the data stream. The global synchronization controller then corrects the relationship between the data stream frequency and its location based on the carrier frequency offset estimate, the remaining carrier frequency offset estimate estimated by the frequency-domain auxiliary pilot, and the remaining timing offset estimate.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication synchronization technology, specifically relating to a wireless continuous communication synchronization method and system based on time-frequency joint feedback correction. Background Technology

[0002] Synchronization in continuous wireless communication is a crucial issue in wireless communication systems. Continuous wireless communication refers to the continuous transmission of data between two or more communication nodes without frequent connection establishment and disconnection. Synchronization in continuous wireless communication systems includes timing synchronization and carrier frequency synchronization. Timing synchronization refers to the slave device in the wireless communication system correctly determining the sampling time of the received signal, ensuring that the sampling point is aligned with the symbol boundary transmitted by the transmitter. Carrier frequency synchronization refers to the slave device adjusting the frequency of its local oscillator to match the carrier frequency of the received signal.

[0003] Existing wireless continuous communication synchronization technologies can be categorized into data-assisted and data-free synchronization based on the presence or absence of data assistance. Blind synchronization without data assistance offers high bandwidth and power utilization, but suffers from slow synchronization speed and limited accuracy. Data-assisted synchronization can be further divided into three types based on data format: auxiliary pilot, training symbols, and inherent signal structure (such as the cyclic prefix of OFDM symbols). Synchronization techniques based on auxiliary pilots have high bandwidth and power consumption overhead, complex design, and high synchronization accuracy. Synchronization techniques based on training symbols are simple to implement and fast, but require other mechanisms to maintain the synchronization state after it is established. Synchronization techniques based on inherent signal structure are simple to implement, but have weak interference resistance and relatively large estimation errors. Summary of the Invention

[0004] This invention provides a wireless continuous communication synchronization method and system based on time-frequency joint feedback correction to solve the aforementioned technical problems, specifically adopting the following technical solution:

[0005] A wireless continuous communication synchronization method based on time-frequency joint feedback correction, comprising:

[0006] The slave device receives wireless communication frames sent by the master device;

[0007] The slave device calculates the carrier frequency offset estimate of the received signal using the preamble sequence. and timing estimates The remaining carrier frequency offset estimate is calculated using auxiliary pilots. and residual timing offset estimate ;

[0008] The slave device estimates the quantity based on timing. Locate the starting point of the data stream;

[0009] The slave device estimates the carrier frequency offset. and residual timing offset estimator The data is fed back to the global synchronization controller, which then corrects the start position of the data stream and the carrier frequency based on the received information.

[0010] Furthermore, before the slave device receives the wireless communication frame sent by the master device, the wireless continuous communication synchronization method based on time-frequency joint feedback correction further includes:

[0011] The slave device continuously captures the continuous wireless communication frames sent by the master device throughout the entire time period. Once a wireless communication frame is captured, the capture of wireless communication frames stops until the end of that wireless communication frame, and then the search for the next wireless communication frame continues.

[0012] Furthermore, the slave device captures the wireless communication frame through the preamble sequence in the wireless communication frame, and the timing estimate is calculated using cross-correlation during the acquisition process. .

[0013] Furthermore, the slave device calculates the end time of the wireless communication frame using the frame header sequence in the wireless communication frame.

[0014] Furthermore, the remaining carrier frequency offset estimate Including integer multiples of frequency offset estimates With fractional frequency offset estimate .

[0015] Furthermore, the fractional octet frequency offset estimate... By eliminating sampling clock frequency offset errors, a corrected fractional frequency offset estimate is obtained. .

[0016] Furthermore, the remaining timing offset estimator Including integer multiples of timing offset With a fractional multiple of timing offset .

[0017] A wireless continuous communication synchronization system based on time-frequency joint feedback correction includes a master unit and several slave units;

[0018] The host includes a frame generation module, a frame control module, and a DAC module;

[0019] The frame generation module generates wireless communication frames, including preamble sequence generation, frame header sequence generation, data sequence generation, and check sequence generation.

[0020] The frame control signal generated by the frame control module is used to control the frame generation module to generate wireless communication frames of different lengths and modulation schemes.

[0021] The DAC module converts the wireless communication frames generated by the frame generation module into digital-to-analog signals and then transmits them via the host's antenna.

[0022] The slave device includes a frame acquisition module, a frame demodulation module, a global synchronization controller, and an ADC module;

[0023] The ADC module performs analog-to-digital conversion on the signals received from the slave device.

[0024] The frame capture module captures the converted signal and calculates the carrier frequency offset estimate. With timed estimates And based on the timed estimate Locate the starting point of the data stream;

[0025] After locating the start point of the data stream, the frame demodulation module of the slave device recovers the data of each frequency point of the wireless communication frame and demodulates it, and calculates the remaining timing offset estimate based on the phase relationship of each frequency point. The remaining carrier frequency offset estimate is calculated based on the phase relationship of different symbols at the same frequency point. ;

[0026] The global synchronization controller estimates the carrier frequency offset. Remaining timing offset estimate With the remaining carrier frequency offset estimate Correct the starting position of the data stream and the carrier frequency.

[0027] Furthermore, the wireless communication signals used for synchronization employ orthogonal frequency division multiplexing (OFDM) signals.

[0028] The advantage of this invention lies in the wireless continuous communication synchronization method and system based on time-frequency joint feedback correction, which utilizes the timing estimate obtained from time-domain preamble sequence estimation. The global synchronization controller performs positive positioning of the data stream frequency based on the carrier frequency offset estimate, the remaining carrier frequency offset estimate obtained from the frequency domain-assisted pilot estimate, and the remaining timing offset estimate. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the wireless communication frame transmission between the host and slave devices of the present invention;

[0031] Figure 2This is a schematic diagram of the wireless continuous communication synchronization method based on time-frequency joint feedback correction of the present invention;

[0032] Figure 3 This is a schematic diagram of the global synchronization controller based on time-frequency joint feedback correction of the present invention;

[0033] Figure 4 This is a schematic diagram of the wireless continuous communication synchronization system based on time-frequency joint feedback correction according to the present invention. Detailed Implementation

[0034] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0035] refer to Figure 1 and Figure 2 As shown, this application provides a wireless continuous communication synchronization method based on time-frequency joint feedback correction, specifically including:

[0036] The slave device receives wireless communication frames sent by the master device;

[0037] The slave device calculates the carrier frequency offset estimate of the received signal using the preamble sequence. and timing estimates The remaining carrier frequency offset estimate is calculated using auxiliary pilots. and residual timing offset estimate ;

[0038] The slave device estimates the quantity based on timing. Locate the starting point of the data stream;

[0039] The slave device estimates the carrier frequency offset. and residual timing offset estimator The data is fed back to the global synchronization controller, which then corrects the start position of the data stream and the carrier frequency based on the received information.

[0040] In a preferred embodiment, before the slave device receives the wireless communication frame sent by the master device, the wireless continuous communication synchronization method based on time-frequency joint feedback correction further includes:

[0041] The slave device continuously captures the continuous wireless communication frames sent by the master device throughout the entire time period. Once a wireless communication frame is captured, the capture of wireless communication frames stops until the end of that wireless communication frame, and then the search for the next wireless communication frame continues.

[0042] Furthermore, the slave device calculates the end time of the wireless communication frame using the frame header sequence in the wireless communication frame.

[0043] The wireless continuous communication synchronization method based on time-frequency joint feedback correction provided in this application utilizes the timing estimate obtained from the time-domain preamble sequence estimation. The data stream is located by inputting the carrier frequency offset estimate from the time-domain preamble sequence, the remaining carrier frequency offset estimate from the frequency-domain auxiliary pilot estimate, and the remaining timing offset estimate into the global synchronization controller, thereby enabling the global synchronization controller to correct the data stream frequency and location. The following details the process of calculating relevant parameters based on the preamble sequence and auxiliary pilot in this application.

[0044] The synchronization method provided in this application utilizes a preamble sequence for timing estimation and carrier frequency offset estimation. The preamble sequence is a periodic sequence with a period of Np, containing Mp repeating periods, and exhibiting good autocorrelation (ZC) characteristics.

[0045] The synchronization method provided in this application uses the cross-correlation between the received preamble sequence r[n] and the transmitted preamble sequence s[n] for time-domain timing estimation. To avoid erroneous decisions caused by accidental interference and low signal-to-noise ratio, the average power of the data stream is used as the threshold for cross-correlation. Correlation peaks exceeding the threshold are detected Mp consecutively, and the interval between two correlation peaks exceeding the threshold is L points. Only then can it be considered a timed estimate, where This is due to correlation peak shift caused by multipath propagation or frequency offset. If the number of correlation peak intervals exceeding the threshold twice consecutively is not within the above range, the timing estimation process restarts. Define the timing function. Normalized value:

[0046]

[0047] Where k represents the cross-correlated displacement. The adjustment coefficient is used to adjust the estimated threshold under different channel conditions. The correlation peak timing point can be determined in the following way:

[0048]

[0049] The synchronization method provided in this application utilizes auxiliary pilots for frequency domain timing estimation and residual timing offset estimation, which are then fed back to the global synchronization controller. The residual timing offset... Divided into integer multiples of timing offset With a fractional multiple of timing offset .

[0050] The phase deflection of the k-th subcarrier introduced by the timing offset is proportional to the subcarrier index:

[0051]

[0052] in Indicates the effective symbol period, Where N is the sampling period and N is the number of subcarriers. These represent the timing offset for the integer sign and the timing offset for the decimal sign, respectively. Common phase error is considered. Sampling clock frequency offset With fractional frequency offset The phase deflection of the k-th subcarrier of the j-th symbol can be obtained as follows:

[0053]

[0054] in , Let the period be the cyclic prefix period. Let each symbol have... The subcarrier number of each pilot is The phase difference between adjacent pilots can be expressed as the pilot subcarrier index difference. Normalized sign timing offset Functions:

[0055]

[0056] A higher-precision normalized timing offset estimate is obtained by averaging the timing offsets of all pilot phase differences. :

[0057]

[0058] because We can obtain:

[0059]

[0060] The above equation shows that the range of symbol timing offset estimation is limited by the phase deflection angle, and... Inversely proportional, and the maximum is .

[0061] Based on the known normalized timing offset estimate, the entire timing offset estimate can be further divided into integer multiples of the timing offset. With a fractional multiple of timing offset To facilitate subsequent corrections.

[0062] The synchronization method provided in this application utilizes the periodicity of the preamble sequence to estimate the carrier frequency offset in the time domain, and uses an auxiliary pilot to estimate the remaining carrier frequency offset in the frequency domain. The remaining carrier frequency offset estimation includes integer multiple frequency offset estimation and fractional multiple frequency offset estimation. Time-domain carrier frequency offset estimation has the advantage of fast synchronization time and reduces carrier interference caused by the carrier frequency offset, thereby achieving higher estimation accuracy of the remaining carrier frequency offset value estimated by the pilot in the frequency domain. By feeding back the frequency-domain remaining carrier frequency estimate to the time domain to correct the data stream, fast and high-precision carrier frequency synchronization can be achieved.

[0063] Define the observation function:

[0064]

[0065] in L represents the nth sampled received signal. Let d represent the correlation window length and d be the symbol timing estimation bias. Then, the time-domain frequency offset estimation result, i.e., the carrier frequency offset estimate, is... It is given by the following formula:

[0066]

[0067] in This indicates the total duration of the leading sequence.

[0068] The synchronization method provided in this application utilizes auxiliary pilots to estimate the remaining carrier frequency offset in the frequency domain, thereby obtaining the estimated remaining carrier frequency offset. Remaining carrier frequency offset estimate Including integer multiples of frequency offset estimates With fractional frequency offset estimate The fractional frequency offset estimation requires an integer frequency offset estimation as a prerequisite. Therefore, the integer frequency offset estimation is performed first, followed by the fractional frequency offset estimation.

[0069] Among them, the integer multiple frequency offset estimate :

[0070]

[0071] W represents the number of consecutive pilots, l represents the sliding window length, and k represents the subcarrier index. This represents the k subcarrier values ​​of the m-th symbol.

[0072] Because the phases of two adjacent symbols at the pilot position have a common factor:

[0073]

[0074]

[0075] The remaining fractional octave frequency offset estimate can be obtained based on the phase difference between the two. :

[0076]

[0077] Where P is the number of pilots involved in the estimation. The above formula calculates... It also includes errors caused by sampling clock frequency offset, which needs to be eliminated. The impact on Further revisions were made to obtain .

[0078] First, let the phase difference between two adjacent symbols at the pilot position be... ,in This indicates the location of the pilot point.

[0079]

[0080] When the number of subcarriers is large, the effect of sampling clock frequency offset cannot be ignored. Based on adjacent pilots... Estimate :

[0081]

[0082] Substituting into (10) and averaging, we obtain the accurate fractional octave frequency offset estimation result:

[0083]

[0084] like Figure 3 As shown, the global synchronization controller estimates the carrier frequency offset. Remaining carrier frequency offset With remaining timing offset estimate = The feedback input corrects the data stream frequency and starting point, where the data stream after the i-th correction... The data stream after the (i-1)th correction The relationship is:

[0085]

[0086]

[0087] Where i is an integer greater than 0. This is the adjustment factor. The data stream after the correction starting point. Data stream before the calibration start point The relationship is:

[0088]

[0089] like Figure 4 As shown, this application also discloses a wireless continuous communication synchronization system based on time-frequency joint feedback correction, comprising: a master unit and several slave units. Both the master and slave units include analog and digital sections in their hardware circuit architecture. The analog section includes analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). The digital section mainly consists of digital signal processing and control loop digital logic circuits, which can be implemented using field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs). The master unit's digital logic generates digital signals with synchronization sequences and data information for transmission. The slave unit's digital logic estimates the offset of the received signal and uses the estimated offset to calculate the control value of the global synchronization controller.

[0090] Specifically, the host computer includes a frame generation module, a frame control module, and a DAC module. The frame generation module generates wireless communication frames, including preamble sequence generation, header sequence generation, data sequence generation, and check sequence generation. The frame control module generates frame control signals to control the frame generation module to generate wireless communication frames of different lengths and modulation schemes. The DAC module converts the wireless communication frames generated by the frame generation module into analog signals before transmitting them via the host computer's antenna.

[0091] The slave device includes a frame capture module, a frame demodulation module, a global synchronization controller, and an ADC module.

[0092] The ADC module performs analog-to-digital conversion on the signal received from the slave device. The frame acquisition module captures the converted signal and calculates the carrier frequency offset estimate. With timed estimates Based on carrier frequency offset estimate The converted signal is then corrected for carrier frequency based on timing estimates. Locate the starting point of the data stream.

[0093] After locating the start point of the data stream, the slave frame demodulation module recovers the data of each frequency point of the wireless communication frame and demodulates it. Based on the phase relationship of each frequency point, it calculates the remaining timing offset estimate. The remaining carrier frequency offset estimate is calculated based on the phase relationship of different symbols at the same frequency point. .

[0094] The global synchronization controller estimates the remaining timing offset. With the remaining carrier frequency offset estimate The starting position of the data stream and the carrier frequency are corrected.

[0095] In the embodiments of this application, the wireless communication signal used for synchronization adopts Orthogonal Frequency Division Multiplexing (OFDM) signal. The master transmits OFDM, and the slave receives the OFDM signal and provides it to the global synchronization controller through a time-frequency joint feedback correction model.

[0096] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A wireless continuous communication synchronization method based on time-frequency joint feedback correction, characterized in that, Include: The slave device receives wireless communication frames sent by the master device; The slave device calculates the carrier frequency offset estimate of the received signal using the preamble sequence. and timing estimates The remaining carrier frequency offset estimate is calculated using auxiliary pilots. and residual timing offset estimate ; The slave device estimates the quantity based on timing. Locate the starting point of the data stream; The slave device estimates the carrier frequency offset. and residual timing offset estimator The data is fed back to the global synchronization controller, which then corrects the start position of the data stream and the carrier frequency based on the received information. Remaining carrier frequency offset estimate Including integer multiples of frequency offset estimates With fractional frequency offset estimate ; Estimates of fractional frequency offset By eliminating sampling clock frequency offset errors, a corrected fractional frequency offset estimate is obtained. The corrected fractional frequency offset estimate As the remaining carrier frequency offset estimate The fractional octave frequency offset estimate is obtained and then processed by the global synchronization controller based on the corrected fractional octave frequency offset estimate. Remaining carrier frequency offset estimate The carrier frequency is corrected.

2. The wireless continuous communication synchronization method based on time-frequency joint feedback correction according to claim 1, characterized in that, Before the slave device receives the wireless communication frame sent by the master device, the wireless continuous communication synchronization method based on time-frequency joint feedback correction further includes: The slave device continuously captures the continuous wireless communication frames sent by the master device throughout the entire time period. Once a wireless communication frame is captured, the capture of wireless communication frames stops until the end of that wireless communication frame, and then the search for the next wireless communication frame continues.

3. The wireless continuous communication synchronization method based on time-frequency joint feedback correction according to claim 1, characterized in that, The slave device captures the wireless communication frame through the preamble sequence in the wireless communication frame. During the acquisition process, the timing estimate is calculated using cross-correlation. .

4. The wireless continuous communication synchronization method based on time-frequency joint feedback correction according to claim 1, characterized in that, The slave device calculates the end time of the wireless communication frame using the frame header sequence in the wireless communication frame.

5. The wireless continuous communication synchronization method based on time-frequency joint feedback correction according to claim 1, characterized in that, Remaining timing offset estimate Including integer multiples of timing offset With a fractional multiple of timing offset .

6. A wireless continuous communication synchronization system based on time-frequency joint feedback correction, characterized in that, It includes a master unit and several slave units; The host includes a frame generation module, a frame control module, and a DAC module; The frame generation module generates wireless communication frames, including preamble sequence generation, frame header sequence generation, data sequence generation, and check sequence generation. The frame control signal generated by the frame control module is used to control the frame generation module to generate wireless communication frames of different lengths and modulation schemes. The DAC module converts the wireless communication frames generated by the frame generation module into digital-to-analog signals and then transmits them via the host's antenna. The slave device includes a frame acquisition module, a frame demodulation module, a global synchronization controller, and an ADC module; The ADC module performs analog-to-digital conversion on the signals received from the slave device. The frame capture module captures the converted signal and calculates the carrier frequency offset estimate. With timed estimates And based on the timed estimate Locate the starting point of the data stream; After locating the start point of the data stream, the frame demodulation module of the slave device recovers the data of each frequency point of the wireless communication frame and demodulates it, and calculates the remaining timing offset estimate based on the phase relationship of each frequency point. The remaining carrier frequency offset estimate is calculated based on the phase relationship of different symbols at the same frequency point. ; The global synchronization controller estimates the carrier frequency offset. Remaining timing offset estimate With the remaining carrier frequency offset estimate Correct the start position of the data stream and the carrier frequency; Remaining carrier frequency offset estimate Including integer multiples of frequency offset estimates With fractional frequency offset estimate ; Estimates of fractional frequency offset By eliminating sampling clock frequency offset errors, a corrected fractional frequency offset estimate is obtained. The corrected fractional frequency offset estimate As the remaining carrier frequency offset estimate The fractional octave frequency offset estimate is obtained and then processed by the global synchronization controller based on the corrected fractional octave frequency offset estimate. Remaining carrier frequency offset estimate The carrier frequency is corrected.

7. The wireless continuous communication synchronization system based on time-frequency joint feedback correction according to claim 6, characterized in that, The wireless communication signals used for synchronization employ orthogonal frequency division multiplexing (OFDM) signals.

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