Frequency offset self-compensation UWB signal detection method

Abstract

The invention discloses a frequency offset self-compensation UWB (ultra wide band) signal detection method, which belongs to the technical field of UWB communication and comprises the following steps of: firstly, performing cross-correlation operation on a signal sampled by an ADC (analog-to-digital converter) and a local sequence; secondly, on the basis of a peak value detection position, calculating a phase difference by utilizing a cross-correlation operation result obtained by calculation and a cross-correlation operation result of a previous symbol; performing phase compensation on the currently calculated cross-correlation result by using phase compensation; adding the cross-correlation result after phase compensation and the cross-correlation result of the previous symbol at the same position; carrying out peak period detection by using the added cross-correlation result, and updating a peak detection position and a peak period detection count value; updating a phase compensation value according to the peak period detection count value and the calculated phase difference; finally, whether the peak period detection count value reaches a set threshold value or not is judged, and if the peak period detection count value reaches the set threshold value, a signal detection result is output; and if not, the steps 1-7 are executed again.

Description

Technical Field

[0001] The invention belongs to the field of ultra-wideband (UWB) communication technology, and in particular relates to a UWB signal detection method with self-compensation for frequency deviation. Background Art

[0002] At present, the outdoor positioning technology based on GNSS is relatively mature, but indoors, the satellite signal is easily blocked and cannot complete the normal positioning service, and the positioning accuracy cannot meet the service requirements. In recent years, people's demand for high-precision positioning services has become stronger. According to statistics, 70%-80% of people's activities take place indoors, so it is of great significance to develop indoor positioning technology. Based on various needs, many corresponding positioning technologies have been demonstrated and achieved good results, such as infrared, radio frequency identification, ultrasound, WIFI, Bluetooth, Zigbee, visual positioning and other technologies. However, they all have their own curves, either low positioning accuracy or harsh requirements on the environment, which cannot meet people's requirements for high accuracy and good environmental adaptability of indoor positioning perception systems. The many advantages of UWB positioning technology are that this technology can achieve high-precision indoor positioning. Compared with other wireless positioning technologies, UWB has many advantages such as strong anti-interference ability, extremely wide bandwidth, fast transmission rate, and low power consumption.

[0003] However, UWB technology is also a type of wireless communication technology. For wireless communication technology, a key technology is signal detection technology. The robustness of the signal detection method is of great significance for improving communication quality and building a robust communication system. Signal detection is the first gateway to identify signals. High-reliability signal detection methods can ensure low false detection rates and low missed detection rates in low signal-to-noise ratio environments. The sensitivity of the signal detection method is directly related to the ranging range of UWB and its application in complex scenarios. Therefore, low-complexity and high-reliability signal detection methods have always been one of the main research directions of wireless communication technology. Summary of the invention

[0004] The purpose of the present invention is to provide a UWB signal detection method with self-compensation for frequency deviation, so as to solve the problems in the prior art of low positioning accuracy, harsh requirements on the environment, and inability to meet people's requirements for high accuracy and good environmental adaptability of indoor positioning perception systems.

[0005] To achieve the above object, the present invention provides a UWB signal detection method with self-compensation for frequency offset, comprising the following steps:

[0006] Step 1: Perform cross-correlation operation on the signal sampled by ADC and the local sequence;

[0007] Step 2: Based on the peak detection position, the phase difference is calculated using the calculated cross-correlation operation result and the cross-correlation operation result calculated for the previous symbol;

[0008] Step 3: Perform phase compensation on the currently calculated cross-correlation result using the phase compensation value;

[0009] Step 4, the cross-correlation result after phase compensation is added to the cross-correlation result of the previous symbol at the same position;

[0010] Step 5: Use the added cross-correlation result to perform peak period detection, and update the peak detection position and peak period detection count value;

[0011] Step 6: Update the phase compensation value according to the peak period detection count value and the calculated phase difference;

[0012] Step 7: Determine whether the peak period detection count value reaches the set threshold. If it reaches the set threshold, output the signal detection result; if not, re-execute steps 1 to 7.

[0013] Preferably, the calculation expression of the cross-correlation operation in step 1 is as follows:

[0014]

[0015] Among them, S C is the result of cross-correlation operation, s sig is the signal sampled by ADC, S loc is the local sequence, N smp is the number of sampling points contained in one symbol period.

[0016] Preferably, in step 2, based on the peak detection position, the phase difference is calculated using the calculated cross-correlation operation result and the cross-correlation operation result calculated for the previous symbol, including the following cases:

[0017] When Pidx<0,

[0018] When Pidx=0, the calculation method is as follows:

[0019]

[0020] When 0 <Pidx<N smp When -1, the calculation method is as follows:

[0021]

[0022] When Pidx=N smp When -1, the calculation method is as follows:

[0023]

[0024] in, is the calculated phase difference, angle() is the method for converting complex numbers into radians, conj() is the conjugate method, Pidx is the current peak detection position index value, S' C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, N smp is the number of sampling points contained in one symbol period.

[0025] Preferably, the specific process of performing phase compensation on the currently calculated cross-correlation result using the phase compensation value in step 3 is as follows:

[0026] When idx≥Pidx-1&&idx≤Pidx+1

[0027]

[0028] otherwise

[0029] S(idx)=S′ C (idx)

[0030] S is the same as S' C The corresponding value after phase compensation is is the phase compensation value, idx is the data index value of the cross-correlation result within a symbol, and the value range is 0 to N smp -1.

[0031] Preferably, the specific expression of adding the cross-correlation result after phase compensation and the cross-correlation result of the previous symbol in the same position in step 4 is as follows:

[0032] When C peak = 0,

[0033] S Add (idx) = abs(S(idx)) + abs(S″ C (idx))

[0034] When C peak >0 hours

[0035] S Add (idx) = abs(S(idx) + S″ C (idx))

[0036] Among them, S Add is the result of adding the correlation results of the two symbols at the same position, idx is the data index of the correlation result in a symbol, C peakis the updated peak cycle detection count value, abs() is the absolute value operation, S' C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, S is the same as S' C The corresponding value after phase compensation.

[0037] Preferably, in step 6, the specific process of updating the phase compensation value according to the peak period detection count value and the calculated phase difference is as follows:

[0038] S601, determine the peak period detection count value C peak Is it 0?

[0039] S602, when the peak period detection count value C peak = 0, the output phase compensation value is

[0040] S603, when the peak period detection count value C peak ≠0, continue C peak Is it less than C' peak ;

[0041] S604, when the peak period detection count value C peak <C' peak When the output phase compensation value is not updated,

[0042] S605, when the peak period detection count value C peak ≥C' peak When C peak Is it equal to 1?

[0043] S606, when the peak period detection count value C peak =1, the output phase compensation value is

[0044] S607: Otherwise, update the phase compensation value

[0045] Among them, φ' c is the phase compensation value before updating; C' peak is the peak period detection count value before updating; is the calculated phase difference.

[0046] Therefore, the present invention adopts the above-mentioned UWB signal detection method with self-compensation of frequency offset, which has the following beneficial effects:

[0047] (1) The sensitivity of signal detection is improved by applying peak enhancement technology to the cross-correlation results;

[0048] (2) By performing carrier frequency offset estimation during signal detection, the influence of carrier frequency offset on signal detection is reduced, and a coarse estimation result of carrier frequency offset is provided, which helps to improve the convergence speed of subsequent carrier frequency offset estimation.

[0049] (3) While ensuring high performance, this method maintains a low implementation complexity, which is conducive to the implementation of practical projects.

[0050] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is an overall flow chart of a UWB signal detection method with self-compensation for frequency offset of the present invention;

[0052] Figure 2 It is a schematic diagram of adding the cross-correlation results in the same position of a UWB signal detection method with self-compensation for frequency offset according to the present invention;

[0053] Figure 3 The present invention discloses a phase compensation value updating process flow chart of a UWB signal detection method with frequency offset self-compensation. DETAILED DESCRIPTION

[0054] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] See also Figure 1-3 , a UWB signal detection method with frequency offset self-compensation, comprising the following steps:

[0056] Step 1: Perform a cross-correlation operation on the signal sampled by the ADC and the local sequence; the calculation expression of the cross-correlation operation is as follows:

[0057]

[0058] Among them, S C is the result of cross-correlation operation, s sig is the signal sampled by ADC, S loc is the local sequence, N smp is the number of sampling points contained in one symbol period;

[0059] Step 2: Based on the peak detection position, the phase difference is calculated using the calculated cross-correlation result and the cross-correlation result calculated for the previous symbol; the peak detection position Pidx comes from the feedback of step 5. And, when there is no feedback at the beginning of the work, the initial value of Pidx is -1. When calculating the phase difference using the calculated cross-correlation result and the cross-correlation result calculated for the previous symbol, first check whether Pidx is reasonable. If Pidx<0, then output

[0060] When Pidx=0, the calculation method is as follows:

[0061]

[0062] When 0 <Pidx<N smp When -1, the calculation method is as follows:

[0063]

[0064] When Pidx=N smp When -1, the calculation method is as follows:

[0065]

[0066] in, is the calculated phase difference, angle() is the method for converting complex numbers into radians, conj() is the conjugate method, Pidx is the current peak detection position index value, S' C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, N smp is the number of sampling points contained in one symbol period;

[0067] Step 3: Use the phase compensation value to perform phase compensation on the currently calculated cross-correlation result; wherein the phase compensation value Derived from step 6, the initial value is When performing compensation, based on the peak detection position Pidx, only the peak position of the cross-correlation result and the two points before and after the peak are compensated. The specific method is as follows:

[0068] When idx≥Pidx-1&&idx≤Pidx+1

[0069]

[0070] otherwise

[0071] S(idx)=S′ C (idx)

[0072] S is the same as S' CThe corresponding value after phase compensation is is the phase compensation value, idx is the data index value of the cross-correlation result within a symbol, and the value range is 0 to N smp -1;

[0073] Step 4: The cross-correlation result after phase compensation is added to the cross-correlation result of the previous symbol at the same position; Figure 2 As shown, the cross-correlation result S(idx) after phase compensation is compared with the cross-correlation result S″ of the previous symbol. C (idx) adds the same position within the symbol. The addition method is as follows:

[0074] When C peak = 0,

[0075] S Add (idx) = abs(S(idx)) + abs(S″ C (idx))

[0076] When C peak >0 hours

[0077] S Add (idx) = abs(S(idx) + S″ C (idx))

[0078] Among them, S Add is the result of adding the correlation results of the two symbols at the same position, idx is the data index of the correlation result in a symbol, C peak is the updated peak cycle detection count value, abs() is the absolute value operation, S' C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, S is the same as S' C The corresponding value after phase compensation;

[0079] Step 5: Use the added cross-correlation result to perform peak period detection, and update the peak detection position and peak period detection count value;

[0080] Step 6: Update the phase compensation value according to the peak period detection count value and the calculated phase difference; the specific process is as follows:

[0081] S601, determine the peak period detection count value C peak Is it 0?

[0082] S602, when the peak period detection count value C peak = 0, the output phase compensation value is

[0083] S603, when the peak period detection count value C peak ≠0, continue C peak Is it less than C' peak ;

[0084] S604, when the peak period detection count value C peak <C' peak When the output phase compensation value is not updated,

[0085] S605, when the peak period detection count value C peak ≥C' peak When C peak Is it equal to 1?

[0086] S606, when the peak period detection count value C peak =1, the output phase compensation value is

[0087] S607: Otherwise, update the phase compensation value

[0088] in, is the phase compensation value before updating; C' peak is the peak period detection count value before updating; is the calculated phase difference.

[0089] Step 7: Determine whether the peak period detection count value reaches the set threshold. If it reaches the set threshold, output the signal detection result; if not, re-execute steps 1 to 7.

[0090] Therefore, the present invention adopts the above-mentioned UWB signal detection method with self-compensation for frequency offset, estimates the carrier frequency offset while detecting the signal, uses the estimated result of the carrier frequency offset to perform phase compensation on the points near the peak of the currently calculated cross-correlation result, and adds the cross-correlation result after phase compensation to the cross-correlation result of the previous symbol to enhance the cross-correlation result, and further enhances the cross-correlation result by performing cumulative filtering on the enhanced cross-correlation result. This method improves the sensitivity of signal detection while ensuring low complexity.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A UWB signal detection method with self-compensation for frequency offset, characterized in that: The following steps are involved: Step 1: Perform cross-correlation operation on the signal sampled by ADC and the local sequence; Step 2: Based on the peak detection position, the phase difference is calculated using the calculated cross-correlation operation result and the cross-correlation operation result calculated for the previous symbol; Step 3: Perform phase compensation on the currently calculated cross-correlation result using the phase compensation value; Step 4, the cross-correlation result after phase compensation is added to the cross-correlation result of the previous symbol at the same position; Step 5: Use the added cross-correlation result to perform peak period detection, and update the peak detection position and peak period detection count value; Step 6: Update the phase compensation value according to the peak period detection count value and the calculated phase difference; Step 7: Determine whether the peak period detection count value reaches the set threshold. If it reaches the set threshold, output the signal detection result; if not, re-execute steps 1 to 7.

2. A UWB signal detection method with frequency offset self-compensation according to claim 1, characterized in that: The calculation expression of the cross-correlation operation in step 1 is as follows: Among them, S C is the result of cross-correlation operation, s sig is the signal sampled by ADC, S loc is the local sequence, N smp is the number of sampling points contained in one symbol period.

3. The UWB signal detection method with frequency offset self-compensation according to claim 2, characterized in that: In step 2, based on the peak detection position, the phase difference is calculated using the calculated cross-correlation operation result and the cross-correlation operation result calculated for the previous symbol, including the following cases: When Pidx<0, When Pidx=0, the calculation method is as follows: When 0 <Pidx<N smp When -1, the calculation method is as follows: When Pidx = N smp When -1, the calculation method is as follows: in, is the calculated phase difference, angle() is the method for converting complex numbers into radians, conj() is the conjugate method, Pidx is the index value of the current peak detection position, S′ C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, N smp is the number of sampling points contained in one symbol period.

4. The UWB signal detection method with frequency offset self-compensation according to claim 3, characterized in that: The specific process of using the phase compensation value to perform phase compensation on the currently calculated cross-correlation result in step 3 is as follows: When idx≥Pidx-1&&idx≤Pidx+1 otherwise S(idx)=S′ C (idx) S is the same as S′ C The corresponding value after phase compensation is is the phase compensation value, idx is the data index value of the cross-correlation result within a symbol, and the value range is 0 to N smp -1.

5. The UWB signal detection method with frequency offset self-compensation according to claim 4, characterized in that: The specific expression for adding the cross-correlation result after phase compensation and the cross-correlation result of the previous symbol in the same position in step 4 is as follows: When C peak = 0, S Add (idx)=abs(S(idx))+abs(S″ C (idx)) When C peak >0 o'clock S Add (idx)=abs(S(idx)+S" C (idx)) Among them, S Add is the result of adding the correlation results of the two symbols at the same position, idx is the data index of the correlation result in a symbol, C peak is the updated peak cycle detection count value, abs() is the absolute value operation, S' C Represents the cross-correlation result of the current symbol, S″ C is the cross-correlation result of the previous symbol, S is the same as S' C The corresponding value after phase compensation.

6. A UWB signal detection method with frequency offset self-compensation according to claim 5, characterized in that: In step 6, the specific process of updating the phase compensation value according to the peak period detection count value and the calculated phase difference is as follows: S601, determine the peak period detection count value C peak Is it 0? S602, when the peak period detection count value C peak = 0, the output phase compensation value is S603, when the peak period detection count value C peak ≠0, continue C peak Is it less than C' peak ; S604, when the peak period detection count value C peak <C' peak When the output phase compensation value is not updated, S605, when the peak period detection count value C peak ≥C' peak When C peak Is it equal to 1? S606, when the peak period detection count value C peak =1, the output phase compensation value is S607: Otherwise, update the phase compensation value in, is the phase compensation value before updating; C' peak is the peak period detection count value before updating; is the calculated phase difference.

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