A signal detection method and device under a large frequency offset

Abstract

The present application belongs to the technical field of wireless communication, and particularly relates to a signal detection method and device under large frequency offset. Firstly, the input signal of the current detection period is obtained, and the frequency domain signal is obtained by conversion to the frequency domain. The number of subcarriers used by the useful signal and the number of useful subcarriers offset out of the band are calculated. Then, the power average of the subcarriers in a specific range of the frequency domain signal is calculated according to the two parameters, and the average of all power averages is calculated as the real-time power of the input signal of the current detection period. Finally, whether the input signal of the current detection period exists useful signal is judged according to the real-time power of the input signal of the current detection period and the sliding average power of the input signal power of the previous detection period. The present application can quickly calculate the real-time power of the input signal of the current detection period, and quickly judge whether the input signal of the current detection period exists useful signal, so as to lock the power amplifier gain in a short time after discovering the signal, and improve the receiving reliability.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to a signal detection method and apparatus with large frequency offset. Background Technology

[0002] In wireless communication systems, a preamble signal is typically used for access during the initial phase of signal transmission, including symbol synchronization, sampling synchronization, and channel estimation. There is usually a certain frequency offset between transmission and reception. The receiving system can tolerate a certain degree of frequency offset. However, a large frequency offset will drastically degrade synchronization performance, leading to reception failure of the current signal frame. Therefore, synchronization has a tolerance range for frequency offset; if this range is exceeded, frequency offset compensation needs to be performed on the incoming signal before synchronization. This compensation value does not need to be very precise; it only needs to be within the synchronization capability range. Subsequent fine-tuning of the frequency offset will make further minor adjustments to ensure the current frame reaches the optimal reception state.

[0003] Simultaneously, this preamble signal is also used for automatic gain control (AGaD), enabling the signal to quickly adjust to a suitable amplitude range, preventing it from becoming too large (oversaturation) or too small (limited accuracy). However, AGaD has a drawback: it is inherently unstable. If signal strength tracking and adjustment continue after synchronization, signal amplitude jitter can easily occur, severely impacting the reliability of channel estimation at the receiver and reducing reception performance. Therefore, signal detection is necessary to lock the power amplifier gain within a short time after signal detection, improving reception reliability. Most existing methods for detecting useful signals are based on synchronization technology, matching the received preamble signal with the known signal at the transmitter to confirm the detection of the target signal. However, this process is time-consuming, and by the time AGaD locks the gain value based on the confirmation message, it is usually too late. Summary of the Invention

[0004] The purpose of this invention is to provide a signal detection method and apparatus with large frequency offset, so as to solve the problem of long time consumption in the existing useful signal detection methods.

[0005] To address the aforementioned technical problems, this invention provides a signal detection method with large frequency offset, comprising the following steps:

[0006] 1) Obtain the input signal for the current detection period and take its N value. fft *l sampling points are used to convert the signal to the frequency domain, resulting in the frequency domain signal Z. j (k), j = 1, 2, ..., l, k is the subcarrier index and k = 0, ..., N fft -1;

[0007] 2) Calculate the number of subcarriers N used for the useful signal.u And the number N of useful subcarrier offset bands fo And then according to N u and N fo Calculate the frequency domain signal Z respectively j (k) Average power P of subcarriers within a specific range jm The subcarriers within the specific range include: subcarriers in the in-band signal excluding those not transmitted, and N subcarriers in the out-of-band signal closest to the in-band signal. fo Each subcarrier; then calculate the average power P of all subcarriers. jm The average value is used as the real-time power of the input signal in the current detection cycle.

[0008] 3) Based on the real-time power P of the input signal in the current detection cycle m (i d The moving average power P of the input signal power in the previous detection period and the previous detection period. ma (i d -1), determine whether there is a useful signal in the input signal of the current detection cycle.

[0009] Its beneficial effects are as follows: Based on the bandwidth characteristics of the input signal, this invention calculates the number of subcarriers used by the available signal and the number of useful subcarriers offset from the outside band. Then, it uses the number of subcarriers used by the available signal and the number of useful subcarriers offset from the outside band to calculate the average power of the subcarriers within a specific range, so as to quickly calculate the real-time power of the input signal in the current detection period. Combined with the moving average power of the input signal power in the previous detection period, it can quickly determine whether there is a useful signal in the input signal in the current detection period, so as to lock the power amplifier gain in a short time after the signal is detected in a timely and rapid manner, thereby improving the reliability of reception. Moreover, this method does not require the precision of signal estimation, as long as it can be determined that the signal frequency offset has exceeded the synchronization capability range of traditional methods.

[0010] Furthermore, if R(i) d If the input signal in the current detection period is greater than SIG_ON_THLD and the Counter is greater than the set number, then it is determined that there is a useful signal in the input signal of the current detection period; where, SIG_ON_THLD is the first ratio threshold, SIG_ON_THLD > 0, and Counter is the number of times the moving average power is calculated.

[0011] Furthermore, the detection method also includes: for the frequency domain signal Z j (k), calculate N near the right outer band and the inner band respectively. fo The sum of the power and value P of each subcarrier pr and N near the left edge of the bandwidth within the band fo The power P of each subcarrier plAnd calculate N near the left outer band and close to the inner band. fo The sum of the power and value P of each subcarrier nl and N near the right edge of the bandwidth within the band fo The sum of the power and value P of each subcarrier nr Then, the observation factor of positive frequency partial correlation is calculated. Observation factors related to negative frequency bias The positive frequency offset factor R is obtained by averaging the observed factors for each positive frequency offset. p The negative frequency offset factor R is obtained by averaging the observed factors for each negative frequency offset. n If R p >FREQ_OFFSET_THLD1 and R n If <FREQ_OFFSET_THLD2, then it is determined that there are at least positive N. fo If the frequency offset of each subcarrier is R n >FREQ_OFFSET_THLD1 and R p If <FREQ_OFFSET_THLD2, then it is determined that there is at least negative N. fo There are 1 subcarrier frequency offset; where FREQ_OFFSET_THLD1 and FREQ_OFFSET_THLD2 are different threshold values, and FREQ_OFFSET_THLD1 > FREQ_OFFSET_THLD2.

[0012] Its beneficial effect is: by statistically analyzing N near the out-of-band area and near the bandwidth edge within the band... fo The energy of each subcarrier can be used to calculate the positive frequency offset factor for examining positive frequency offset and the negative frequency offset factor for examining negative frequency offset, thereby enabling rapid identification of the frequency deviation of the signal.

[0013] Furthermore, the average power P of the subcarriers within a specific range jm The calculation formula is:

[0014]

[0015] In the formula, P j (k) is the frequency domain signal Z j The power of subcarrier k of (k).

[0016] Furthermore, N near the inner band of the right outer band. fo The sum of the power and value P of each subcarrier pr and N near the left edge of the bandwidth within the band fo The power P of each subcarrier pl They are respectively:

[0017]

[0018]

[0019] In the formula, P j (k) is the frequency domain signal Z j The power of subcarrier k of (k).

[0020] Furthermore, N near the inner band on the left outer band. fo The sum of the power and value P of each subcarrier nl and N near the right edge of the bandwidth within the band fo The sum of the power and value P of each subcarrier nr They are respectively:

[0021]

[0022]

[0023] In the formula, P j (k) is the frequency domain signal Z j The power of subcarrier k of (k).

[0024] Furthermore, the number N of subcarriers used by the useful signal u And the number N of useful subcarrier offsets outside the band fo They are respectively:

[0025]

[0026]

[0027] In the formula, B is the bandwidth of the wireless signal; F s F is the sampling frequency; o The maximum supported frequency offset; round() indicates rounding operation.

[0028] Furthermore, if it is determined that the input signal in the previous detection cycle contains a useful signal, and the current detection cycle satisfies R(i) d If SIG_OFF_THLD < SIG_OFF_THLD, then it is determined that there is no useful signal in the input signal of the current detection period; where SIG_OFF_THLD is the second ratio threshold, and SIG_OFF_THLD < 0.

[0029] Its beneficial effects are: by using the above conditions, it is possible to quickly determine whether the signal has disappeared with high accuracy, ensuring timely adjustment of abnormal signals and ensuring that the automatic gain function is updated normally until the normal signal arrives.

[0030] Furthermore, the moving average power for each detection period is: if the number of times the moving average power is calculated, Counter, satisfies Counter≤N ma ,but otherwise Where, N ma To calculate the number of cycles required for the moving average power, P ma (i d P represents the moving average power under the current detection conditions. ma This is the moving average power from the previous detection period.

[0031] Its beneficial effect is that it can improve the calculation efficiency by using the detection period within the sliding window to calculate the moving average power.

[0032] To address the aforementioned technical problems, the present invention also provides a signal detection device with large frequency offset, comprising a memory and a processor, wherein the processor is used to execute program instructions stored in the memory to implement the signal detection method with large frequency offset described above.

[0033] Its beneficial effect is that it ensures the effective and reliable execution of the signal detection method with large frequency offset. Attached Figure Description

[0034] Figure 1 This is a flowchart of the method of the present invention;

[0035] Figure 2 This is a schematic diagram of the specific subcarrier positions inside and outside the wireless signal band of the present invention;

[0036] Figure 3 This is a schematic diagram of the specific subcarrier positions inside and outside the wireless signal band in the FFT transform of the present invention;

[0037] Figure 4 This is a schematic diagram illustrating the frequency offset of specific subcarriers within and outside the wireless signal band according to the present invention. Detailed Implementation

[0038] The main concept of this invention lies in employing an efficient convergence method to quickly calculate the real-time power of the input signal and the moving average power of previous signals based on the bandwidth characteristics of the input signal, thereby determining whether a useful signal exists in the current input and simultaneously identifying whether the frequency deviation of the signal reaches a large frequency deviation range. Based on this, a signal detection method and a signal detection device under large frequency deviations can be implemented. To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the invention. It should be understood that the scope of protection of this invention is not limited to the specific embodiments.

[0039] Method Implementation Examples:

[0040] This embodiment focuses on a transceiver device based on OFDM technology in a wireless communication system. It assumes the wireless signal input is z(n) = i(n) + j*q(n), n = 0, 1, ..., and the detection period is T, which in this embodiment is T = 600. Each period is further divided into two equal-length small processing units N. fft This refers to the computation length of the FFT. Considering the calculation of intermediate variables and logical judgments, generally, T > 2 * N. fft In this embodiment, N fft =256. Frequency offset F o The number of subcarriers that cause the in-band signal to shift out of the band is known, let's assume it's N. fo The number of cycles required for power moving average is N. ma (N in this embodiment) ma =6), the index value of the number of signal detections is i. d The counter for the moving average is Counter, i d Both the initial values ​​of the counter and the ADC are set to 0, and the sampling frequency F of the ADC analog-to-digital conversion is set to 0. s =2.08MHz. For example... Figure 1 As shown, the specific detection methods and processes are as follows:

[0041] 1)i d First, increment by 1. The input signal z(n) is detected with a period T, and the first N values ​​are taken in each period. fft *Two sampling points are used, and N is performed twice on both the front and back parts. fft =256-point FFT (Discrete Fourier Transform) to obtain Z j (k)(j=1 and 2, respectively Z1(k) and Z2(k)), k=0,...,N fft -1. In the frequency domain, the powers corresponding to each subcarrier k are P1(k) and P2(k), respectively.

[0042] 2) Based on the bandwidth B of the wireless signal and N in the FFT fft and the sampling frequency F of the digital signal s The maximum frequency offset F supported by the synchronization algorithm o The number of subcarriers N used for the useful signal can be roughly calculated. u and the number N of useful subcarriers offset out of band fo In this embodiment, N is calculated. fo =3, N u =104. Therefore, Z1(k) in N is further calculated. fo The specific range below (including: subcarriers in the in-band signal excluding non-transmitted signals and N in the out-of-band signal close to the in-band) fo The average power P of the subcarriers within the subcarriers (number of subcarriers) 1m The specific calculation formula is as follows:

[0043]

[0044]

[0045] In the formula, round() represents the rounding operation.

[0046] The principle of formula (2) is explained below. Assuming there is no frequency offset in the received signal, the center of the bandwidth is the default location where no signal is transmitted; if F occurs... o If the frequency offset is N, then the subcarrier number N fo The corresponding power is not included in the calculation, so excluding the power of this subcarrier requires the following power statistics: [1, N] fo -1] and [N fo +1, ], and the other half is offset by N fo The power of each subcarrier [ N fft -1], see details Figure 4 This is the actual location of the FFT calculation output. Due to the periodicity of the FFT, the frequency domain values ​​of the left half have been moved to the right.

[0047] 3) Similarly, the power mean P in the second half can be obtained using a formula similar to formula (2). 2m .

[0048] 4) such as Figure 2 and Figure 3 As shown, N in the vicinity of the left band is calculated based on P1(k). fo The energy P of each subcarrier pl (i.e., power and value), N near the right band fo The energy P of each subcarrier pr Right now:

[0049]

[0050] 5) Calculate P pr and P pl The ratio of the positive frequency partial correlation is used to obtain the observation factor.

[0051] 6) Similarly, according to equation (4), we can obtain the N near the left band outside the band related to P1(k). fo The energy P of each subcarrier nl N near the right band fo The energy P of each subcarrier nr And calculate the ratio. This is an observation factor with negative frequency bias.

[0052]

[0053] 7) Based on P2(k), another comparison value is obtained using a formula similar to that in formulas (3) and (4). and

[0054] 8) Then, calculate the average value of each positive frequency offset observation factor to obtain the positive frequency offset factor. The negative frequency offset factor is obtained by averaging the observed factors for each negative frequency offset.

[0055] 9) Calculate the average power during the detection period using the following formula, and use it as the real-time power of the input signal during the detection period:

[0056]

[0057] 10) Calculate the moving average power for each detection period according to formula (6) or (7). First, increment Counter. If Counter is less than or equal to N... ma If the condition is met, then follow equation (6); otherwise, follow equation (7).

[0058]

[0059]

[0060] 11) Calculate the ratio of the current period's power to the previous moving average power:

[0061]

[0062] It should be noted that dB is conventionally used to represent strength, so the calculation of log10 is used in formula (8).

[0063] 12) If R(i) d If the value is greater than SIG_ON_THLD and Counter is greater than 2, then update the moving average P. ma (i d ) = P m (i d Counter = 1, and the signal flag SigOnFlag = 1. The default value of SIG_ON_THLD is 3dB. It should be noted that R(i d When Counter is less than or equal to 1, it is easy to cause large jitter and misjudgment. Therefore, the condition for updating the moving average here includes "Counter is greater than 2".

[0064] 13) If SigOnFlag = 1, if R(i dIf the value is less than SIG_OFF_THLD, then update the moving average P. ma (i d ) = P m (i d Counter = 1, and the signal flag SigOnFlag = 0. The default value of SIG_OFF_THLD is -2.5dB.

[0065] 14) If SigOnFlag = 1, then check whether R is satisfied. p >FREQ_OFFSET_THLD1 and R n <FREQ_OFFSET_THLD2: If satisfied, then determine that there are at least positive N. fo One subcarrier frequency offset; otherwise, determine whether R is satisfied. n >FREQ_OFFSET_THLD1 and R p <FREQ_OFFSET_THLD2: If satisfied, then determine that there is at least negative N. fo Subcarrier frequency offset. The threshold value FREQ_OFFSET_THLD1 can be set to 1.8dB, and the threshold value FREQ_OFFSET_THLD2 can be set to 0.4dB.

[0066] 15) Repeat steps 1) to 14) to perform signal detection and large frequency offset estimation in a cyclical (detection cycle).

[0067] In this embodiment, each cycle is divided into two small processing units N of equal length. fft As another implementation, a cycle can be divided into three, four or even more small processing units of equal length. However, too many processing units require more preamble signals and processing time, which is not conducive to the rapid detection of useful signals. It is necessary to select the number of small processing units of equal length according to the actual situation.

[0068] In summary, the present invention has the following characteristics: 1) The method provided by the present invention does not require estimating the precise frequency offset of the signal, as long as it can be determined that the frequency offset of the signal has exceeded the synchronization capability range of the traditional method; 2) It can quickly determine whether there is a useful signal and can quickly determine whether the signal has disappeared, with high accuracy, and can make timely adjustments to abnormal signals to ensure that the automatic gain function is updated normally until a normal signal arrives.

[0069] Device Example:

[0070] An embodiment of a signal detection device with large frequency deviation according to the present invention includes a memory, a processor, and an internal bus. The processor and the memory communicate and exchange data with each other through the internal bus. The memory stores program instructions, and the processor executes these program instructions to implement the signal detection method with large frequency deviation described in the method embodiment of the present invention. The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing devices. The memory can be various types of memory that store information using electrical energy, such as RAM, ROM, etc., or other types of memory.

[0071] The present invention has been described in detail above through specific embodiments, which clarifies the features of the present invention. However, these descriptions do not constitute a limitation on the present invention. On the contrary, the purpose of the present invention is to cover various technical changes with equivalent arrangements within the scope of the patent application to be made by the present invention.

Claims

1. A signal detection method with a large frequency offset, characterized in that, Includes the following steps: 1) Obtain the input signal for the current detection cycle and take its value. One sampling point, The computation length for converting from the time domain to the frequency domain is calculated, and the signal is obtained by converting to the frequency domain. , , The subcarrier sequence number and ; 2) Calculate the number of subcarriers used for the useful signal. and the number of useful subcarriers offset out of band And then according to and Calculate frequency domain signals Average power of subcarriers within a specific range The subcarriers within the specific range include: subcarriers in the in-band signal excluding those that do not transmit signals, and subcarriers in the out-of-band signal that are close to the in-band signal. Subcarriers; then calculate the average power of all obtained subcarriers; The sums are then averaged, and the result is used as the real-time power of the input signal for the current detection cycle. ; 3) Calculate the moving average power of the input signal power in the current detection period. The calculation method is as follows: if the number of times the moving average power is calculated... satisfy ,but ,otherwise ;in, The number of cycles required to calculate the moving average power. This is the index value for the number of signal detections. , These are the moving average power values ​​for the previous and current detection periods, respectively. 4) According to and Determine whether there is a useful signal in the input signal of the current detection period: If >SIG_ON_THLD and If the number exceeds the set number, it is determined that the input signal in the current detection cycle contains a useful signal; where, SIG_ON_THLD is the first ratio threshold, SIG_ON_THLD > 0; 5) If >SIG_ON_THLD and If the number exceeds the set number, update the moving average. Counter = 1, and there is a signal flag SigOnFlag = 1; if SigOnFlag = 1, and If <SIG_OFF_THLD, then update the moving average. When Counter = 1, there is a signal flag SigOnFlag = 0; when SigOnFlag = 1, then check if there is a positive flag. Subcarrier frequency offset or negative Subcarrier frequency offset.

2. The signal detection method under large frequency deviation according to claim 1, characterized in that, The number of counters is set to 2; the default value of SIG_ON_THLD is 3dB; the default value of SIG_OFF_THLD is -2.5dB.

3. The signal detection method under large frequency deviation according to claim 1, characterized in that, The detection method further includes: For frequency domain signals Calculate the right outer band near the inner band respectively. Power and value of each subcarrier and within the band near the left edge of the bandwidth Power and value of each subcarrier And calculate the area near the left outer band and inside the band. Power and value of each subcarrier and within the band near the right edge of the bandwidth Power and value of each subcarrier Then, the observation factor of positive frequency partial correlation is calculated. Observation factors related to negative frequency bias The positive frequency offset factor is obtained by averaging the observed factors for each positive frequency offset. The negative frequency offset factor is obtained by averaging the observed factors for each negative frequency offset. ; like and Then it is determined that at least one positive If the frequency offset of each subcarrier is... and Then it is determined that there is at least one negative. Each subcarrier frequency offset; among them and For different threshold values, and > .

4. The signal detection method under large frequency deviation according to claim 1, characterized in that, Average power of subcarriers within a specific range The calculation formula is: In the formula, Frequency domain signal subcarrier The power.

5. The signal detection method under large frequency deviation according to claim 3, characterized in that, Right outer band near the inner band Power and value of each subcarrier and within the band near the left edge of the bandwidth Power of each subcarrier They are respectively: In the formula, Frequency domain signal subcarrier The power.

6. The signal detection method under large frequency deviation according to claim 3, characterized in that, Left outer band near the inner band Power and value of each subcarrier and within the band near the right edge of the bandwidth Power and value of each subcarrier They are respectively: In the formula, Frequency domain signal subcarrier The power.

7. The signal detection method under large frequency deviation according to any one of claims 1 to 6, characterized in that, Number of subcarriers used for useful signals and the number of useful subcarriers offset out of band They are respectively: In the formula, The bandwidth of the input wireless signal; The sampling frequency; This represents the maximum frequency offset supported by the synchronization algorithm; round() indicates rounding operation.

8. The signal detection method under large frequency deviation according to claim 1, characterized in that, If the input signal in the previous detection cycle is determined to contain a useful signal, and the current detection cycle satisfies... If SIG_OFF_THLD < 0, it is determined that there is no useful signal in the input signal of the current detection period; where SIG_OFF_THLD is the second ratio threshold, and SIG_OFF_THLD < 0.

9. The signal detection method under large frequency deviation according to claim 3, characterized in that, Threshold Set to 1.8dB, threshold value Set to 0.4dB.

10. A signal detection device with large frequency offset, characterized in that, The system includes a memory and a processor, wherein the processor executes program instructions stored in the memory to implement a signal detection method with large frequency offset, the method comprising the following steps: 1) Obtain the input signal for the current detection cycle and take its value. One sampling point, The computation length for converting from the time domain to the frequency domain is calculated, and the signal is obtained by converting to the frequency domain. , , The subcarrier sequence number and ; 2) Calculate the number of subcarriers used for the useful signal. and the number of useful subcarriers offset out of band And then according to and Calculate frequency domain signals Average power of subcarriers within a specific range The subcarriers within the specific range include: subcarriers in the in-band signal excluding those that do not transmit signals, and subcarriers in the out-of-band signal that are close to the in-band signal. Subcarriers; then calculate the average power of all obtained subcarriers; The sums are then averaged, and the result is used as the real-time power of the input signal for the current detection cycle. ; 3) Calculate the moving average power of the input signal power in the current detection period. The calculation method is as follows: if the number of times the moving average power is calculated... satisfy ,but ,otherwise ;in, The number of cycles required to calculate the moving average power. This is the index value for the number of signal detections. , These are the moving average power values ​​for the previous and current detection periods, respectively. 4) According to and Determine whether there is a useful signal in the input signal of the current detection period: If >SIG_ON_THLD and If the number exceeds the set number, it is determined that the input signal in the current detection cycle contains a useful signal; where, SIG_ON_THLD is the first ratio threshold, SIG_ON_THLD > 0; 5) If >SIG_ON_THLD and If the number exceeds the set number, update the moving average. Counter = 1, and there is a signal flag SigOnFlag = 1; if SigOnFlag = 1, and If <SIG_OFF_THLD, then update the moving average. When Counter = 1, there is a signal flag SigOnFlag = 0; when SigOnFlag = 1, then check if there is a positive flag. Subcarrier frequency offset or negative Subcarrier frequency offset.

11. The signal detection device under large frequency deviation according to claim 10, characterized in that, The number of counters is set to 2; the default value of SIG_ON_THLD is 3dB; the default value of SIG_OFF_THLD is -2.5dB.

12. The signal detection device under large frequency deviation according to claim 10, characterized in that, The detection method further includes: For frequency domain signals Calculate the right outer band near the inner band respectively. Power and value of each subcarrier and within the band near the left edge of the bandwidth Power and value of each subcarrier And calculate the area near the left outer band and inside the band. Power and value of each subcarrier and within the band near the right edge of the bandwidth Power and value of each subcarrier Then, the observation factor of positive frequency partial correlation is calculated. Observation factors related to negative frequency bias The positive frequency offset factor is obtained by averaging the observed factors for each positive frequency offset. The negative frequency offset factor is obtained by averaging the observed factors for each negative frequency offset. ; like and Then it is determined that at least one positive If the frequency offset of each subcarrier is... and Then it is determined that there is at least one negative. Each subcarrier frequency offset; among them and For different threshold values, and > .

13. The signal detection device under large frequency deviation according to claim 10, characterized in that, Average power of subcarriers within a specific range The calculation formula is: In the formula, Frequency domain signal subcarrier The power.

14. The signal detection device under large frequency deviation according to claim 12, characterized in that, Right outer band near the inner band Power and value of each subcarrier and within the band near the left edge of the bandwidth Power of each subcarrier They are respectively: In the formula, Frequency domain signal subcarrier The power.

15. The signal detection device under large frequency deviation according to claim 12, characterized in that, Left outer band near the inner band Power and value of each subcarrier and within the band near the right edge of the bandwidth Power and value of each subcarrier They are respectively: In the formula, Frequency domain signal subcarrier The power.

16. The signal detection device with large frequency deviation according to any one of claims 10 to 15, characterized in that, Number of subcarriers used for useful signals and the number of useful subcarriers offset out of band They are respectively: In the formula, The bandwidth of the input wireless signal; The sampling frequency; This represents the maximum frequency offset supported by the synchronization algorithm; round() indicates rounding operation.

17. The signal detection device under large frequency deviation according to claim 10, characterized in that, If the input signal in the previous detection cycle is determined to contain a useful signal, and the current detection cycle satisfies... If SIG_OFF_THLD < 0, it is determined that there is no useful signal in the input signal of the current detection period; where SIG_OFF_THLD is the second ratio threshold, and SIG_OFF_THLD < 0.

18. The signal detection device under large frequency deviation according to claim 12, characterized in that, Threshold Set to 1.8dB, threshold value Set to 0.4dB.

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