WO2009143736A1

WO2009143736A1 - Method and device eliminating interference in signals in short range wireless network

Info

Publication number: WO2009143736A1
Application number: PCT/CN2009/071595
Authority: WO
Inventors: 刘培; 张兴炜; 韩瑜; 赵玉萍
Original assignee: 华为技术有限公司
Priority date: 2008-05-31
Filing date: 2009-04-30
Publication date: 2009-12-03
Also published as: CN101594166A; CN101594166B

Abstract

A method and device eliminating narrowband interference in signals in short range wireless network. The method comprises: eliminating the narrowband interference signal of which the center frequency is zero in the received baseband signal and obtaining the baseband signal from which the zero frequency interference has been eliminated; estimating the center frequency of the narrowband interference signal in the received baseband signal and obtaining the estimated center frequency value; eliminating the interference signal of which the estimated center frequency is non-zero and obtaining the signal from which the interference has been eliminated. The method and device have good compatibility for zero frequency and non-zero frequency narrowband interference and can improve the anti-jamming tolerance and demodulation performance.

Description

Method and device for eliminating interference in signal in short-range wireless network This application claims to be submitted to the Chinese Patent Office on May 31, 2008, and the application number is 200810067554. 8. The invention is entitled "Method for Eliminating Interference in Signal in Short-Range Wireless Network" The priority of the Chinese Patent Application, the entire disclosure of which is incorporated herein by reference.

Technical field

The present invention relates to the field of communications and computer technologies, and in particular, to a method and apparatus for eliminating interference in a signal in a short-range wireless network. BACKGROUND OF THE INVENTION

The low-rate, low-cost, low-power short-range wireless transmission system for short-distance information transmission is one of the research hotspots in the field of wireless communication in recent years. The low-cost, low-power target puts high demands on the design of the receiver scheme. It requires the receiver to be as simple as possible and low in cost, that is, to minimize the implementation while maintaining the performance of the system. The complexity.

The short-range wireless transmission system uses a direct sequence spread spectrum technology that is simple to implement but can greatly improve system performance. The direct sequence spread spectrum technology can bring about the spread spectrum gain, so it can effectively resist the narrowband interference in the channel to some extent. The spread spectrum gain determines the countermeasure capability of narrowband interference. When the narrowband interference power is large, the relatively small spread spectrum gain cannot effectively disperse the attenuation interference, so that the receiver cannot work normally. At this time, corresponding measures need to be taken to counter the strong narrowband interference in the system.

There are two main methods for narrowband interference cancellation: the time domain based narrowband interference cancellation method and the transform domain based narrowband interference cancellation method. The time domain based narrowband interference cancellation methods mainly include linear prediction adaptive filtering method and nonlinear predictive adaptive filtering method, which usually adopts Least Mean Square (LMS) algorithm and recursive least squares (RLS, Recursive Least). The Squares algorithm uses the error values of the filter output and the reference signal to adjust the coefficients of the filter to eliminate narrowband interference. The transform domain-based narrowband interference cancellation method transforms the time domain signal into the frequency domain, detects the frequency component of the interference signal, and attenuates the frequency component, thereby achieving the purpose of eliminating interference.

In the process of implementing the present invention, the inventor has found that: a time domain-based narrowband interference cancellation method requires an iterative operation, so the implementation complexity is high; a transform domain based narrowband interference cancellation method uses a time-frequency domain transform. Therefore, it requires a large amount of hardware resources, which greatly increases the complexity of the receiver. This is undoubtedly not applicable to short-range wireless network receivers with low complexity, low power consumption and low cost. Summary of the invention

Embodiments of the present invention provide a method for eliminating narrowband interference in a signal in a short-range wireless network, which can reduce complexity.

The technical solution adopted by the embodiment of the present invention is as follows: A method for eliminating narrowband interference in a signal in a short-range wireless network, the method comprising:

Removing the narrowband interference signal whose center frequency is zero in the received baseband signal, and obtaining a baseband signal for removing the zero frequency interference;

Estimating a center frequency of the narrowband interference signal in the baseband signal from which the zero-frequency interference is removed, to obtain a center frequency of the interference signal;

The baseband signal with zero-frequency interference is filtered to remove an interference signal whose center frequency is non-zero.

Embodiments of the present invention provide a method for signal center frequency estimation, which can reduce complexity.

The technical solution adopted by the embodiment of the present invention is as follows: A method for estimating a signal center frequency, the method comprising: detecting each peak point of a signal to be estimated, and obtaining a peak sequence including all peak points;

Counting the number of samples between adjacent peak points in the to-be-estimated signal as a sequence of time intervals between the peak points; performing statistical judgment on the frequency point values corresponding to the time interval sequence between the peak points, A center frequency value of the waveform of the signal to be estimated is obtained.

Embodiments of the present invention provide a means for eliminating interference in a signal in a short-range wireless network, which can reduce complexity.

The technical solution adopted by the embodiment of the present invention is as follows: A device for eliminating interference in a signal in a short-range wireless network, including:

a zero-frequency interference removing module, configured to remove a narrow-band interference signal whose center frequency is zero in the received baseband signal, to obtain a baseband signal that removes zero-frequency interference;

a frequency estimation module, configured to estimate a center frequency of the narrowband interference signal in the baseband signal of the zero-frequency interference obtained by the zero-frequency interference removal module, to obtain a center frequency of the narrowband interference signal;

a non-zero frequency interference removing module, configured to filter the baseband signal that removes zero frequency interference, remove a interference signal whose center frequency is non-zero according to a center frequency obtained by the frequency estimation module, and obtain a non-zero frequency interference signal Target signal frame.

Embodiments of the present invention provide a frequency estimation module capable of reducing complexity.

The technical solution adopted by the embodiment of the present invention is as follows: A frequency estimation module includes:

a detecting unit, configured to detect each peak point of the signal to be estimated, to obtain a peak sequence including all peak points; a statistical unit, configured to count the number of samples between adjacent peak points obtained by the detecting unit in the signal to be estimated, as a sequence of time intervals between peak points;

And a determining unit, configured to perform a statistical decision on the frequency point value corresponding to the time interval sequence between the peak points of the statistical unit statistics, to obtain a center frequency value of the waveform of the signal to be estimated.

Embodiments of the present invention provide a receiver for eliminating interference in a signal in a short-range wireless network, which can reduce complexity.

The technical solution adopted by the embodiment of the present invention is as follows: A receiver for eliminating interference in a signal in a short-range wireless network, including:

a signal frame detection module, configured to perform a detection process on the target signal frame for the baseband signal obtained by the zero-frequency interference removal module to remove the zero-frequency interference, to obtain a target signal frame;

a signal frame synchronization module, configured to perform a synchronization process on the target signal frame for the target signal frame output by the signal frame detection module, to obtain a synchronized target signal frame;

a frequency estimation module, configured to estimate a center frequency of the narrowband interference signal in the baseband signal output by the signal frame synchronization module, to obtain a center frequency of the narrowband interference signal;

a non-zero frequency interference removing module, configured to filter a synchronized target signal frame output by the signal frame synchronization module, and remove a narrowband interference signal whose center frequency is non-zero according to a center frequency obtained by the frequency estimation module, to obtain Target signal frame unless zero-frequency interference;

And a data despreading and demodulating module, configured to despread and demodulate the target signal frame output by the non-zero frequency interference removing module, and output a binary data stream.

It can be seen from the above technical solutions that the embodiments of the present invention have good compatibility with zero-band interference of zero-frequency and non-zero-frequency, and can significantly improve the anti-interference tolerance and demodulation performance of the system. The embodiment of the present invention performs the elimination of narrowband interference in the time domain, and does not need to introduce a complicated time-frequency transform operation, thereby reducing hardware requirements. In addition, the embodiments of the present invention are capable of performing targeted interference cancellation by distinguishing between zero-frequency interference and non-zero-frequency interference. The zero-frequency interference can be directly removed by the waveform fitting method. When there is no zero-frequency interference, the waveform fitting elimination method has no effect on the non-zero-frequency interference and the target signal frame; the non-zero-frequency interference needs to estimate the frequency component of the interference signal in advance, and then adopts The corresponding notch is removed directly. The frequency estimation algorithm disclosed in the embodiment of the present invention has good frequency estimation accuracy for a narrowband waveform having a center frequency value of an integral multiple of a finite number of basic bandwidths, and it is particularly important that the method only uses data weighted average, statistical counting, Methods such as threshold comparison and thus have extremely low complexity. Therefore, the embodiments of the present invention are well suited for use in an application environment where high complexity is required. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and other drawings can be obtained from those skilled in the art without any inventive labor.

1 is a flowchart of a method for canceling narrowband interference in a short-range wireless network according to an embodiment of the present invention; FIG. 2 is a flowchart of a method for estimating a center frequency of a signal according to an embodiment of the present invention;

FIG. 3 is a structural diagram of an apparatus for canceling interference in a signal in a short-range wireless network according to an embodiment of the present invention; FIG. 4 is a structural diagram of a receiver for canceling interference in a signal in a short-range wireless network according to an embodiment of the present invention; A structure diagram of a frequency estimation module provided by an embodiment of the present invention;

6 is a structural diagram of a receiver for canceling interference in a signal in a short-range wireless network according to Embodiment 1 of the present invention; FIG. 7 is a flowchart of a method for estimating a center frequency of a signal according to Embodiment 1 of the present invention;

8 is a flowchart of a statistical decision step in a method for estimating a center frequency of a signal according to Embodiment 1 of the present invention; FIG. 9 is a PER_SNR graph of a receiver according to Embodiment 1 of the present invention;

10 is a PER_CIR graph of a receiver according to Embodiment 1 of the present invention;

FIG. 11 is a graph showing a correct probability _SNR of a method for estimating a center frequency of a signal according to Embodiment 1 of the present invention; FIG. 12 is a PER_SNR graph of a receiver according to Embodiment 2 of the present invention. Detailed ways

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following description is only some embodiments of the present invention, Other embodiments of the invention may be derived from these embodiments without the inventive effort.

Referring to FIG. 1, an embodiment of the present invention provides a method for eliminating narrowband interference in a short-range wireless network, where the method includes the following steps:

Step S1, removing a narrowband interference signal whose center frequency is zero in the received baseband signal, to obtain a baseband signal for removing zero-frequency interference;

Step S2, estimating a center frequency of the narrowband interference signal in the baseband signal from which the zero-frequency interference is removed, to obtain an estimated center frequency value; Step S3, filtering the baseband signal that removes the zero-frequency interference, removing the interference signal whose center frequency is non-zero, and obtaining the baseband signal for canceling the interference.

It can be seen from the above technical solutions that the embodiments of the present invention have good compatibility with zero-band and non-zero-frequency narrow-band interference, and can significantly improve the anti-interference tolerance and demodulation performance of the system. Embodiments of the present invention have lower complexity than conventional narrowband interference cancellation methods. The time-domain-based adaptive filtering interference cancellation method does not pre-emptively estimate the statistical characteristics (such as frequency components) of the interference signal, but eliminates the interference signal at any frequency point. The introduction of highly complex iterative operations is therefore highly demanding on hardware. The transform domain-based interference cancellation method eliminates interference by detecting the frequency component of the interference signal in the frequency domain and attenuating the frequency component. This method usually requires fast Fourier transform (FFT) technology to complete the time-frequency domain of the signal. Transforming, taking up more hardware resources, increases the complexity and production cost of the receiver. The embodiment of the present invention performs the elimination of narrowband interference in the time domain, and does not need to introduce a complicated time-frequency transform operation, thereby reducing hardware requirements. In addition, the embodiments of the present invention are capable of performing targeted interference cancellation by distinguishing between interferences of the same nature but different cancellation methods, such as zero-frequency interference and non-zero-frequency interference. The zero-frequency interference can be directly removed by the waveform fitting method. When there is no zero-frequency interference, the waveform fitting elimination method has no effect on the non-zero-frequency interference and the target signal frame; the non-zero-frequency interference needs to estimate the frequency component of the interference signal in advance, and then adopts The corresponding notch is removed directly.

The method for estimating the center frequency of the signal in the step S2 of the method for eliminating interference in the signal in the short-range wireless network according to the embodiment of the present invention is described in detail below. The signal to be estimated in step S10 may be a narrowband interference signal in the baseband signal from which the zero-frequency interference is removed in step S2.

In this embodiment, referring to FIG. 2, the method for estimating the center frequency of the signal in step S2 may adopt the following steps: Step S10: Smoothing the signal to be estimated to obtain a processed signal;

In this embodiment, the signal waveform χ(«) to be estimated is smoothed, and some false spikes due to random noise are removed by smoothing to obtain a smoothed signal waveform.

In this embodiment, the method for determining the smoothing of the narrowband signal waveform may be: assuming that the narrowband signal waveform is x(") (« = 1, 2, ..., N), and the smoothed signal waveform is ( « = 1, 2, ..., N ), the smoothing parameter is k, and the A value is obtained from the empirical value of the narrowband signal waveform; then when the narrowband signal waveform has the subscript value at [A + 1, N -A: ], between each adjacent + 1 narrow-band signal sample value weighted summation, where the weight can be expressed as (« + ), its value is obtained from the empirical value of the narrow-band signal waveform, and then, will be weighted The result of the summation operation averages the values of the +1 narrowband signal samples, that is, the smoothed signal waveform is obtained when the subscript value of the narrowband signal waveform is not in the range of [A + 1, N - A:], The value of Bay is taken as the value of x(«). This step can be expressed as the following formula:

Step S20, detecting peak points of the smoothed signal to obtain a peak sequence including all peak points; in this embodiment, detecting peak points of the smoothed signal waveform to obtain peaks including all peak points Sequence / ^(«);

In this embodiment, the method for detecting the peak point of the narrowband signal waveform may be: shifting the narrowband signal waveform sample by point, if the amplitude of a certain sample is larger than the amplitude of the two preceding and succeeding samples, The sample point is the peak point of the narrowband signal waveform, and the sample sequence number is recorded, and all the peak sample numbers constitute the peak sequence.

Step S30, the number of samples between adjacent peak points in the statistical signal is used as a time interval sequence between the peak points; in this embodiment, the number of samples between adjacent peak points in the statistical signal waveform, As a sequence of time intervals between peak points t (/ _;

In this embodiment, the method for counting the number of samples between adjacent peak points in the narrowband signal waveform may be: according to the peak sequence / («) of the narrowband signal waveform detected in step S20, the subtraction operation can be calculated The number of samples between every two adjacent peak points, the value of which can be used as the time interval between the peak points;

Step S40: Perform statistical judgment on the frequency point value corresponding to the time interval sequence between the peak points to obtain a center frequency value of the estimated signal waveform.

In the present embodiment, the frequency point value corresponding to the time interval sequence t(«) between the peak points is statistically determined, and the center frequency value of the estimated signal waveform is obtained.

In this embodiment, the method for performing statistical decision on the frequency point value corresponding to the time interval sequence between the peak points may be: a one-to-one correspondence between the time interval between the peak points and the corresponding frequency point value The relationship, if the time interval between peak points is small, indicates that the center frequency of the narrowband signal waveform is higher, and vice versa. According to the time interval between adjacent peak points in the narrowband signal waveform counted in step S30, the estimated value of the narrowband signal center frequency can be obtained by the following method: Let the possible center frequency value of the narrowband signal waveform be: where = ∞ Δ / , where is an integer, Δ/ is the basic bandwidth of the narrowband signal, < F ₂ where < ₂ is the lower frequency value, and ₊₁ < ^ ₊₂ < ... < ^ is the higher frequency value.

The system initialization frequency level is 0. If the proportion of the high frequency component is more than the judgment center frequency value is otherwise, if the proportion of the secondary high frequency component is more than _ ₂ %, the center frequency value is judged and so on, until the center frequency value is judged to be ₊₁ . Frequency component. Among them, the values of h _N —%, _ ₂ % are preset.

If none of the above conditions are met, the center frequency of the narrowband signal is a lower frequency point (less than ₊₁ ), and the set frequency level is 1. In order to reduce the false decision of the false spike caused by random noise, the above steps need to be repeated. S10. Step S20 and step S30, respectively performing a second smoothing process on the narrowband signal, a peak point of the detection signal, and a time interval between the statistical peak points. Then, the following statistical judgment is made: If the proportion of the lower frequency component is more than /^%, the center frequency value is judged; otherwise, if the proportion of the secondary low frequency component is more than /^_ ₂ %, the center frequency is judged The value is F _p _ _x ; and so on, if none of the above conditions are met, the center frequency of the narrowband waveform is . When the estimated center frequency value is obtained, the current frequency level is modified to be 0. Where ί _ρ / ₀ , the equivalent is preset.

If the current frequency level of the system is 0, the resulting center frequency is the center frequency of the estimated narrowband signal.

It should be noted that step S10 in the method for estimating the signal center frequency in the embodiment is optional, and may be included in a preferred embodiment, and may not be included in other embodiments.

The signal center frequency estimation method in this embodiment has a resolution greater than the basic bandwidth of the signal, and the implementation complexity is low. The signal having the center frequency of the integer multiple of the finite number of basic bandwidths for the signal to be estimated is a preferred frequency estimation method. .

The frequency estimation algorithm disclosed in the embodiment of the present invention has good frequency estimation accuracy for a narrowband waveform having a center frequency value of an integral multiple of a finite number of basic bandwidths, and it is particularly important that the method only uses data weighted average, statistical counting, Methods such as threshold comparison and thus have extremely low complexity. Therefore, embodiments of the present invention are well suited for use in applications where high complexity is required.

The technical solutions provided by the embodiments of the present invention include, but are not limited to, the foregoing methods, and those skilled in the art can obtain the estimated center frequency values in step S2 in the embodiment of the present invention according to the disclosed content in the prior art.

It should be noted that the method for estimating the center frequency of the narrowband signal according to the embodiment of the present invention is not limited to the application in the short-range wireless network. For other networks, it is necessary to estimate a narrowband signal having an integer multiple of the center frequency of a limited basic bandwidth, especially In the case where the low complexity is required, the technical solution of the embodiment of the present invention can be adopted. In different applications, according to the empirical value of the narrowband signal to be estimated, the smoothing processing parameter Κ weight coefficient + and the threshold value of each frequency component may be modified.

Embodiments of the present invention provide an apparatus for eliminating interference in a signal in a short-range wireless network, which can reduce complexity.

Referring to FIG. 3, an embodiment of the present invention provides a device for eliminating interference in a short-range wireless network, where the device includes: a zero-frequency interference removal module 10, a frequency estimation module 20, and a non-zero-frequency interference removal module 30.

The zero-frequency interference removing module 10 is configured to remove a narrow-band interference signal whose center frequency is zero in the received baseband signal, to obtain a baseband signal that removes zero-frequency interference;

In the present embodiment, the zero-frequency interference removing module 10 removes the narrow-band interference signal whose center frequency is zero in the received baseband signal by using the waveform fitting method.

The frequency estimation module 20 is configured to narrow the baseband signal of the zero-frequency interference obtained by the zero-frequency interference removal module 10 Estimating the center frequency of the interfering signal to obtain the center frequency of the narrowband interfering signal;

The non-zero frequency interference removing module 30 is configured to filter the baseband signal that removes the zero frequency interference, remove the interference signal whose center frequency is non-zero according to the center frequency obtained by the frequency estimation module 20, and obtain the baseband signal that removes the non-zero frequency interference. .

Further, the device in the embodiment of the present invention may be a receiver. As shown in FIG. 4, the receiver may further include a signal frame detecting module 40, a signal frame synchronization module 50, and a data despreading and demodulating module 60, where:

The signal frame detection module 40 is configured to detect the baseband signal of the non-zero frequency interference removal module 30 and remove the non-zero frequency interference, to obtain a target signal frame;

The signal frame synchronization module 50 is configured to synchronize the target signal frame output by the signal frame detection module 40 to obtain a synchronized target signal frame.

The data despreading and demodulating module 60 is configured to perform despreading and demodulating the target signal frame output by the signal frame synchronization module 50 to obtain a binary data stream.

As shown in FIG. 5, the frequency estimation module 20 provided by the embodiment of the present invention includes:

The detecting unit 202 is configured to detect each peak point of the signal to be estimated, and obtain a peak sequence including all peak points; and a statistical unit 204, configured to count the number of samples between adjacent peak points in the signal to be estimated, as a peak point Sequence of time intervals between;

The determining unit 206 is configured to perform statistical judgment on the frequency point value corresponding to the time interval sequence between the peak points to obtain a center frequency value of the waveform of the signal to be estimated.

Further, the frequency estimation module 20 provided by the embodiment of the present invention may further include a smoothing unit 200, configured to perform smoothing processing on the signal to be estimated, and send the processed signal to the detecting unit 202;

It should be noted that the receiver for eliminating interference in the signal in the short-range wireless network provided by the embodiment of the present invention can reduce the complexity and effectively eliminate the interference in the signal. If the center frequency of the narrowband interference is zero, the zero-frequency interference removal module 10 of the receiver front end will first remove it, and the frequency estimation module 20 estimates that its center frequency is zero, and the non-zero frequency interference removal module 30 does not perform any processing; If the center frequency of the narrowband interference is non-zero, the interference signal of the zero-frequency interference removal module 10 fitted by the waveform fitting method is approximately 0, the received signal waveform is unchanged, and the frequency estimation module 20 estimates the center thereof. The frequency is removed in the non-zero frequency interference removal module 30.

A receiver for eliminating interference in a signal in a short-range wireless network provided by an embodiment of the present invention will be described in detail below.

Embodiment 1

In this embodiment, the short-range wireless network selects a wireless personal area network (WPAN) based on the IEEE 802. 15. 4b international standard, and the narrowband interference is selected based on the ISO/IEC 18000-6 (Type B) standard. Radio Frequency Identification (RFID) signal. This embodiment will explain how to apply the narrowband signal frequency estimation method provided by the present invention and the receiver device against narrowband interference in a short-range wireless network with reference to the accompanying drawings, so that the IEEE 802. 15.4b receiver receives IEEE 802. 15. 4b. The signal and the baseband of the RFID signal are mixed, and the narrowband interference of the RFID signal is effectively removed, and the correct demodulation of the IEEE 802. 15. 4b signal is realized.

It is advisable to set the IEEE 802. 15. 4b signal rate to 250kbps and the chip rate to lMchip/s. The RFID signal information rate is 40 kbps, the symbol rate is 80 ksymbol/s, and the center frequency may be 0, 250 kHz, 500 kHz, and 750 kHz, wherein the RFID signal with a center frequency of 0 coincides with the center frequency of the IEEE 802. 15.4b signal. An RFID signal whose center frequency is not 0, the shift of the spectrum is equivalent to multiplying the RFID signal having a center frequency of 0 by a sinusoidal signal having the center frequency.

Since the center frequency of the RFID signal does not necessarily coincide with the center frequency of the IEEE 802. 15. 4b signal, and the IEEE 802. 15.4b receiver cannot know the frequency of the RFID signal in the received baseband signal at this time, it is necessary to adopt the embodiment provided by the embodiment of the present invention. The frequency estimation method estimates the frequency of the interference signal.

The receiver structure provided in this embodiment is as shown in FIG. 6, and includes:

In this embodiment, the zero-frequency interference removal module 10 uses a least squares polynomial fitting method for the baseband signal R(«) received by the receiver to remove the RFID narrowband interference signal with a center frequency of zero in R(«). Obtaining a baseband signal Z^) that removes zero-frequency interference;

The signal frame detection module 40 is configured to complete a detection process on the target signal frame for the baseband signal that removes the zero-frequency interference, to obtain a target signal frame.

In this embodiment, the signal frame detection module 40 performs a IEEE 802. 15. 4b signal frame on the baseband signal Z(«) for removing the zero-frequency interference for the baseband signal Z(«) by using the self-sliding correlation method of the received signal. The detection process obtains a mixed signal with the presence of an IEEE 802. 15.4b signal frame / ;

The signal frame synchronization module 50 is configured to perform a synchronization process on the target signal frame for the output signal of the signal frame detection module 40 to obtain a synchronized target signal frame.

In this embodiment, the signal synchronization module 50 performs a synchronization process on the IEEE 802. 15. 4b signal frame for the mixed signal frame /) («) by using a method in which the received signal is related to the local signal slip to obtain the synchronized IEEE 802. 15. Mixed signal of 4b signal frame

The frequency estimation module 20 is configured to estimate a center frequency of the narrowband interference signal in the baseband signal output by the signal frame synchronization module 50, to obtain a center frequency of the narrowband interference signal;

In this embodiment, the frequency estimation module 20 narrows the RFID band whose center frequency in the mixed signal is non-zero. The signal is subjected to frequency estimation. First, a plurality of synchronization symbols of the known IEEE 802. 15.4b signal frame are removed from the mixed signal of the synchronized IEEE 802. 15.4b signal frame, and then the frequency estimation method disclosed in the embodiment of the present invention is used. , get the estimated frequency value

The non-zero frequency interference removing module 30 is configured to filter the baseband signal output by the signal frame synchronization module 50, and remove the interference signal whose center frequency is non-zero according to the center frequency obtained by the frequency estimation module 20, thereby obtaining the non-zero frequency interference. Target signal frame.

In this embodiment, if the frequency value of ^(«) is not zero, the non-zero frequency interference removing module 30 designs a band rejection filter with the frequency value as the center frequency and the bandwidth of the RFID signal bandwidth of 80 KHz. Zero-frequency RFID interference signal; if the estimated frequency value is zero, no processing is performed;

The data despreading and demodulating module 60 is configured to despread and demodulate the target signal frame output by the non-zero frequency interference removing module 30, and output a binary data stream.

In this embodiment, the data despreading and demodulating module 60 performs despreading and demodulating, and outputting binary data for the signal frame N (n, (in the present embodiment, an IEEE 802. 15. 4b signal frame) after the interference is removed. Stream S).

The specific working process of the IEEE 802. 15. 4b receiver provided by the embodiment of the present invention is:

The receiver receives the baseband signal R(«);

The baseband signal R(«) is passed through the zero-frequency interference removal module 10, and the least squares polynomial fitting method is used to remove the RFID narrowband interference signal with zero center frequency in R(«), and the baseband signal Z with zero-frequency interference is obtained. («);

The baseband signal Z(«) is passed through the signal frame detection module 40, and the baseband signal for removing the zero-frequency interference is subjected to the detection process of the IEEE 802. 15.4b signal frame by using the self-sliding correlation method of the received signal, and the IEEE 802.15 is obtained. . 4b mixed signal of signal frame

The mixed signal frame is passed through the signal frame synchronization module 50, and the received signal is synchronized with the local signal, and the IEEE 802. 15. 4b signal frame is synchronized to obtain a mixed signal of the synchronized IEEE 802. 15. 4b signal frame. ^«) ;

Frequency estimation of the RFID narrowband signal with a non-zero center frequency in the mixed signal ^(«), first removing the known IEEE 802. 15. 4b signal from the mixed signal of the synchronized IEEE 802. 15. 4b signal frame a plurality of synchronization symbols of the frame, and then using the frequency estimation method disclosed in the embodiment of the present invention to obtain an estimated frequency value

The mixed signal is removed by non-zero frequency interference by the module 30. If the estimated frequency value is not zero, design a band rejection filter with the frequency value as the center frequency and the bandwidth of the RFID signal bandwidth of 80 KHz to remove the non-zero frequency RFID interference signal; if the frequency value is zero, do not do any deal with;

The signal frame N(«) after the interference is removed is despread and demodulated by the data despreading and demodulating module 60, and the IEEE 802.15 4b signal frame is despread and demodulated, and the binary data stream 3 («) is output. Specifically, the signal center frequency estimation method used in this embodiment is shown in FIG. 7, and the specific workflow is as follows:

Step S71, smoothing the narrowband signal waveform x(«) of the RFID to obtain a smoothed signal waveform, wherein the smoothing processing parameter A is 2, and the weight coefficient + value is a constant 1;

Step S72, detecting peak points of the smoothed RFID narrowband signal waveform to obtain a sequence containing all peak points / ^(«);

Step S73, counting the number of samples between adjacent peak points in the waveform of the narrowband signal of the RFID, as a time interval sequence t(«) between the peak points;

Step S74, the time interval between the peak points T sequence ( «) corresponding to the frequency values of the decision statistic shown in Figure 8, the center frequency to obtain a value of the estimated narrowband signal RFID, where N = _4, F 4 = 750KHz, F ₃ = 500KHz, F ₂ = 250KHz, F _x = 0Hz , Ρ = 2 , h3% = 62%, h2% = 65%, 11% = 50%.

Since the RFID narrowband signal has only a limited number of possible center frequency values, and no processing is required when the center frequency is 0, in practice, several possible band rejection filter coefficients can be designed in advance and stored. The filter coefficients can be selected based on the estimated frequency point values, thereby further reducing the complexity of the receiver.

The comparison between the embodiments of the present invention and other narrowband interference cancellation methods is as follows: There are mainly two commonly used narrowband interference cancellation methods: a time domain based narrowband interference cancellation method and a transform domain based narrowband interference cancellation method. The time domain based narrowband interference cancellation methods mainly include linear prediction adaptive filtering method and nonlinear predictive adaptive filtering method. It usually adopts minimum mean square error (LMS) algorithm and recursive least squares (RLS) algorithm, and uses filter output. And the error value of the reference signal to adjust the coefficient of the filter to eliminate narrow-band interference, this method requires iterative operation, and the implementation complexity is high; the narrow-band interference cancellation method based on the transform domain transforms the time domain signal into the frequency domain, detecting interference The frequency component of the signal is attenuated and the interference is eliminated. This method requires a large amount of hardware resources and high complexity due to the use of time-frequency domain transformation. The signal frequency estimation method disclosed in the embodiment of the present invention detects the peak point by smoothing the narrowband signal to be estimated, and counts the number of samples between the adjacent peak points as a time interval sequence between the peak points, thereby obtaining an estimated narrowband signal waveform. The center frequency value is less complex and easier to implement than the previous two methods.

9 and FIG. 10 respectively illustrate the demodulation of the 15.4 signal, the system error frame, by the IEEE 802. 15.4b receiver designed by the embodiment of the present invention in the presence of the RFID narrowband signal having the center frequency of zero. Rate (PER, Packet Error Rate) varies with the signal-to-noise ratio (SNR) and the system's PER vs. Carrier Interference Ratio (CIR). It can be seen from the simulation results that, after the receiver device against narrowband interference in the short-range wireless network provided by the embodiment of the present invention, the performance of the system is close to that of the non-RFID narrowband signal. Figure 11 shows the correct probability of the signal frequency estimation algorithm provided by the embodiment of the present invention. The figure assumes that the IEEE 802. 15. 4b signal power is constant. As can be seen from Fig. 11, as the signal-to-noise ratio increases, the correct probability of the frequency estimation algorithm increases, and as the CIR decreases, the correct probability of the frequency estimation algorithm increases. It should be noted that when the CIR is large, that is, the narrowband interference energy is low, the frequency estimation module will estimate the current interference frequency value to be 0 with a very high probability, and the system will not do any processing and will not affect the IEEE 802. 15. 4b signal. Correct demodulation. Therefore, the frequency estimation algorithm has low complexity and high frequency estimation performance.

Embodiment 2

It should be noted that the location of the module in the receiver structure for canceling interference in the signal in the short-range wireless network provided by the embodiment of the present invention is not limited to the location given in Embodiment 1, as in the embodiment, the frequency estimation module and The non-zero frequency interference removal module can be placed before the signal frame detection module, and the other system parameters are set as in the first embodiment, as shown in FIG.

12 shows an IEEE 802. 15.4b receiver designed by the embodiment of the present invention to demodulate a 15.4 signal in the presence of an RFID narrowband signal having a center frequency of 250 kHz. The frame error rate (PER) of the system varies with the signal to noise ratio. (SNR) curve. It can be seen that the receiver provided by the embodiment of the present invention can significantly improve the performance of the system compared with the conventional IEEE 802. 15. 4b receiver.

The comparison between the receiver of the embodiment of the present invention and other corresponding devices is as follows: There are two main types of processing for narrowband interference devices: one is to pass a signal (usually performing analog processing) through a narrowband trap or a trap group, The method generally uses some estimation of the frequency of the interference signal, and according to the estimation result, a narrowband notch device is placed in the place where the interference signal is present; the other is a device based on frequency domain cancellation, and the filter is used in the frequency domain data. In addition to the influence of interference, this method is applicable to the case of known interference bandwidth and location. When the location of the interference in the frequency domain, the interference bandwidth, and the number cannot be clearly determined, the method has certain limitations because the design is completely Adaptively varying filters have certain difficulties. In addition, phase-locked loops can also be used to track interfering signals, but analog technology has its limitations and is often not flexible enough. Compared with these technologies, the receiver for eliminating interference in the short-range wireless network disclosed in the embodiment of the present invention has good compatibility with zero-band and non-zero-frequency narrow-band interference, and the receiver implementation complexity is low. Compared with the conventional receiver, the receiver provided by the embodiment of the invention can significantly improve the resistance of the system to narrowband interference.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus a necessary general hardware platform, and of course, can also be through hardware, but in many cases, the former is a better implementation. the way. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a readable storage medium, such as a floppy disk of a computer. , a hard disk or an optical disk, etc., including instructions for causing a device (which may be a server, or a network device, etc.) to perform the methods described in various embodiments of the present invention. The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any change or replacement that can be easily conceived by those skilled in the art within the technical scope of the present invention is All should be covered by the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Claim

A method for eliminating narrowband interference in a short-range wireless network, the method comprising: removing a narrowband interference signal having a center frequency of zero in a received baseband signal, and obtaining a baseband for removing zero-frequency interference Signal

2. The method according to claim 1, wherein the step of estimating a center frequency of the narrowband interference signal in the baseband signal for removing the zero-frequency interference comprises:

Detecting respective peak points of the narrowband interference signal in the baseband signal from which the zero-frequency interference is removed, to obtain a peak sequence including all peak points;

Counting the number of samples between adjacent peak points in the narrowband interference signal in the baseband signal of the zero-frequency interference as a time interval sequence between the peak points;

A statistical decision is made on the frequency point value corresponding to the time interval sequence between the peak points to obtain a center frequency value of the narrowband interference signal waveform in the baseband signal from which the zero frequency interference is removed.

3. The method according to claim 2, further comprising: before detecting the peak points of the narrowband interference signal in the baseband signal for removing the zero-frequency interference:

Smoothing the narrowband interference signal in the baseband signal with zero frequency interference removed.

4. A method for estimating a frequency of a signal center, the method comprising:

Detecting respective peak points of the signal to be estimated, and obtaining a peak sequence including all peak points;

The method according to claim 4, further comprising: before the detecting each peak point of the signal to be estimated, performing: smoothing the signal to be estimated.

A device for eliminating interference in a signal in a short-range wireless network, the device comprising: a zero-frequency interference removal module, configured to remove a narrow-band interference signal with a center frequency of zero in a received baseband signal, Obtaining a baseband signal that removes zero-frequency interference;

a frequency estimation module, configured to estimate a center frequency of the narrowband interference signal in the baseband signal of the zero-frequency interference obtained by the zero-frequency interference removal module, to obtain a center frequency of the narrowband interference signal; a non-zero frequency interference removing module, configured to filter the baseband signal that removes zero frequency interference, remove a interference signal whose center frequency is non-zero according to a center frequency obtained by the frequency estimation module, and obtain a non-zero frequency interference signal Baseband signal.

The apparatus according to claim 6, wherein the zero-frequency interference removing module is specifically configured to remove a narrowband interference signal whose center frequency is zero in the received baseband signal by using a waveform fitting method, A baseband signal is obtained that removes zero-frequency interference.

8. The device according to claim 6, wherein the device further comprises:

a signal frame detection module, configured to detect, by using the non-zero frequency interference removal module, a non-zero frequency interference baseband signal, to obtain a target signal frame;

a signal frame synchronization module, configured to synchronize a target signal frame output by the signal frame detection module to obtain a synchronized target signal frame;

The data despreading and demodulating module is configured to perform despreading and demodulating the synchronized target signal frame output by the signal frame synchronization module to obtain a binary data stream.

9. The apparatus according to claim 6, wherein the frequency estimation module comprises:

a detecting unit, configured to detect each peak point of the signal to be estimated, to obtain a peak sequence including all peak points; and a statistical unit, configured to collect samples between adjacent peak points obtained by the detecting unit in the signal to be estimated Number, as a sequence of time intervals between peak points;

The device of claim 9, wherein the estimating module further comprises:

And a smoothing unit, configured to perform smoothing processing on the to-be-estimated signal, and send the processed signal to the detecting unit.

11. A frequency estimation module, comprising:

The module of claim 11, further comprising:

13. A receiver for eliminating interference in a signal in a short-range wireless network, the receiver comprising: a zero-frequency interference removal module, configured to remove narrow-band interference with a center frequency of zero in a received baseband signal. Signal, got To remove the baseband signal of zero-frequency interference;

The receiver of claim 13, wherein the frequency estimation module comprises:

And a determining unit, configured to perform a statistical decision on the frequency point value corresponding to the time interval sequence between the peak points obtained by the statistical unit, to obtain a center frequency value of the waveform of the signal to be estimated.

The receiver of claim 14, wherein the frequency estimation module further comprises:

The receiver according to claim 13, wherein the zero-frequency interference removal module is specifically configured to remove a center frequency of the received baseband signal by using a least squares polynomial fitting method. The narrowband interference signal is used to obtain a baseband signal that removes zero-frequency interference.