Receiver based on M-FSK modulation and receiving method thereof

Abstract

A receiver and a receiving method based on M-FSK modulation that are highly scalable and have good receiving performance are provided. The present invention includes performing M-FSK demodulation on a frame structure including a preamble frame, a SYNC frame, and a data frame, specifically, performing M-FSK demodulation on a preamble frame of a repeating sequence by adopting a time-frequency synchronization technique of autocorrelation, performing M-FSK demodulation on a preamble frame of a non-repeating sequence by adopting a time-frequency synchronization technique of cross-correlation sliding FFT, and performing M-FSK demodulation on a SYNC frame and a data frame by adopting an M-FSK data demodulation technique of self-adaptive scalable FFT. The present invention employs the technical solution based on advanced M-FSK to achieve low sensitivity and at the same time adapt to various multipath and Doppler scenarios.

Description

[Technical field]

[0001] The present application relates to the field of communications technology, and in particular to a receiver based on M-FSK modulation and a receiving method thereof. [Background technology]

[0002] Demodulation is the process of recovering information from a modulated signal that carries that information. In various information transmission or processing systems, the sender modulates a carrier wave with the information to be transmitted, producing a signal that carries this information. The receiver must recover the transmitted information before it can be used, which is demodulation. Summary of the Invention [Problem to be solved by the invention]

[0003] Most of the traditional M-FSK demodulation techniques are based on analog methods or perform matching correlation detection methods in the time domain, which have low scalability and poor receiving performance. [Means for solving the problem]

[0004] This application provides a receiving method based on M-FSK modulation, which demodulates a frame structure including a preamble frame, a SYNC frame and a Data frame by M-FSK demodulation, where M-FSK refers to M-order frequency shift keying, which selects one frequency point from M consecutive orthogonal modulation frequency points in the frequency domain according to the required modulation bits of each symbol to transmit, where M is an exponent of 2, and each M-FSK symbol can transmit log2(M) bits, and the other two important parameters are the minimum frequency point interval SCS and each symbol time length T, and the schematic diagram of M-FSK modulation is shown in Figure 8.

[0005] Demodulating the preamble frame; if the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, adopting an autocorrelation time-frequency synchronization technique to demodulate the preamble frame M-FSK; if the preamble frame is a non-repetitive sequence, adopting a cross-correlation sliding FFT time-frequency synchronization technique to demodulate the preamble frame M-FSK; demodulating the preamble frame; Demodulating the SYNC frame and / or the DATA frame, adopting a self-adaptive scalable FFT M-FSK data demodulation technique to perform M-FSK demodulation of the SYNC frame and the DATA frame; Includes.

[0006] When the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, the preamble frame sequence is autocorrelated with the previous and next to obtain a new sequence, and based on satisfying a threshold, the synchronization point is the autocorrelation peak value point which is the corresponding preamble synchronization point, and when the autocorrelation value is maximum, it indicates that the complete preamble sequence has been received, the above-mentioned receiving method based on M-FSK modulation.

[0007] The frequency offset calculated based on the autocorrelation value of the maximum correlation width, the number of time delay symbols zz, and the M-FSK symbol duration T is: CFO = phase(Corr(K max )) / (2π*(T*zz)), where phase represents the desired phase and is calculated based on multiple real and imaginary values, and Corr(k) is a new sequence obtained by autocorrelating the preamble frame sequence before and after the preamble frame sequence.

[0008] The above-mentioned receiving method based on M-FSK modulation, in which the non-repeating sequence includes a non-repeating sequence based on M-FSK sequence modulation, and is also suitable for other sequences or other modulation schemes, and supports the use of CAZAC sequences and ZadoffChu sequences.

[0009] The cross-correlation sliding FFT time-frequency synchronization technology is specifically based on the sliding FFT method of receiving an M-FSK modulation sequence and a local sequence, and the scalable local sequence is used to perform a conjugate dot product with the received signal of the same sampling rate, which performs the function of deserializing information, transforming it into the frequency domain, and obtaining the maximum value and the position information of the frequency domain. At this time, the correlation peak value and the value for frequency offset estimation are obtained, and the peak values ​​at different times and the maximum value of the peak values ​​are compared, and if they are greater than a certain threshold, that is, the time synchronization point of the preamble, and the frequency offset value is obtained based on the frequency magnitude represented by the position of the frequency point at the synchronization time and the interval between the DC frequency points. This is the above-mentioned receiving method based on M-FSK modulation.

[0010] The self-adaptive scalable FFT M-FSK data demodulation technology specifically demodulates the transmission symbols of scalable Advanced M-FSK based on the frequency point interval SCS / symbol time length / number of modulation frequency points, and self-adaptively demodulates the data demodulation based on M-FSK modulation, in the above-mentioned receiving method based on M-FSK modulation.

[0011] The receiving method based on the above M-FSK modulation is based on the multi-antenna combining technology, in which the frequency domain peak value is the correlation combining coefficient, and the data symbol demodulation combining is a combining based on each M-FSK symbol, and the combining weight value of each antenna is the value that corresponds most to all the frequency points of the energy after the M-FSK symbol is transformed into the frequency domain, or only the maximum value on the modulation frequency point is retained.

[0012] The receiving method based on the above M-FSK modulation, which is based on a non-repeated sequence synchronous multi-antenna synthesis technology, and the synthesis weight value of each antenna is the value that corresponds most greatly to the energy in the frequency domain of the M-FSK symbol.

[0013] In the present application, M-FSK demodulation is performed on a frame structure including a preamble frame, a SYNC frame, and a data frame. Specifically, When the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, the autocorrelation time-frequency synchronization technique is adopted to perform SNR detection and time-frequency synchronization of the preamble frame; when the preamble frame is a non-repetitive sequence, the cross-correlation sliding FFT time-frequency synchronization technique is adopted to perform SNR detection and time-frequency synchronization of the preamble frame; demodulating the preamble frame; Demodulating the SYNC frame and / or the DATA frame by adopting a self-adaptive scalable FFT M-FSK data demodulation technique to obtain maximum likelihood detection performance; The present invention further provides a receiving method based on M-FSK modulation, including:

[0014] The receiving method based on the above M-FSK modulation is based on the multi-antenna combining technology, in which the frequency domain peak value is the correlation combining coefficient, and the data symbol demodulation combining is a combining based on each M-FSK symbol, and the combining weight value of each antenna is the value that corresponds most to all the frequency points of the energy after the M-FSK symbol is transformed into the frequency domain, or only the maximum value on the modulation frequency point is retained.

[0015] The receiving method based on the above M-FSK modulation, which is based on a non-repeated sequence synchronous multi-antenna synthesis technology, and the synthesis weight value of each antenna is the value that corresponds most greatly to the energy in the frequency domain of the M-FSK symbol.

[0016] Specifically, SNR detection and time-frequency synchronization are 1. Synchronizing the time point according to the non-repeated preamble sequence, the frequency domain peak value or the energy around the peak value of the deserialized information is the signal energy, and the other than the signal energy is the noise energy, and calculating the SNR according to the signal energy and the noise energy; 2. According to the M-FSK data symbol, after transforming into frequency domain, the total energy of the frequency domain peak value or the points near the peak value is the signal energy, and the frequency points other than the signal energy are the noise energy, and the SNR is calculated according to the signal energy and the noise energy; The above-mentioned receiving method based on M-FSK modulation includes:

[0017] The present application further provides a receiver based on M-FSK modulation, the receiver comprising: a receiving method for M-FSK modulation according to any one of the above claims.

[0018] The beneficial effects achieved by the present application are as follows:

[0019] 1. This application uses the relevant receiver technology and is based on Advanced M-FSK to achieve low sensitivity while adapting to various multipath and Doppler scenarios.

[0020] 2. This application adopts synchronization technology, which greatly improves the sensitivity of the detection technology, and can synchronize the frequency even when the frequency offset is large, thereby saving the TCXO on the transmitting side.

[0021] 3. This application adopts self-adaptive FFT-based demodulation technology, which can achieve maximum likelihood demodulation performance.

[0022] 4. This application adopts multi-antenna synthesis technology, allowing the receiving side to obtain energy and diversity gains.

[0023] 5. The M-FSK energy detection and SNR measurement method of the present invention enables the receiving side to obtain the corresponding receiving conditions relatively accurately.

[0024] In order to more clearly describe the technical solutions in the embodiments of the present invention or the prior art, the following will briefly describe the drawings that need to be used in the description of the embodiments or the prior art. Of course, the drawings in the following description are only some of the embodiments described in the present invention, and those skilled in the art can also obtain other drawings based on these drawings. [Brief description of the drawings]

[0025] [Figure 1] 1 is a schematic diagram of an M-FSK digital demodulation advanced receiver algorithm based on zero IF; [Diagram 2] FIG. 2 is a schematic diagram of a receiving method based on M-FSK modulation provided by a first embodiment of the present application; [Diagram 3] 1 is a schematic diagram of a receiver receiving a repeating sequence of preamble frames; [Figure 4] 1 is a schematic diagram showing the relationship between preamble frame sequences and autocorrelation values. FIG. [Diagram 5] 1 is a schematic diagram of a receiver receiving a preamble frame of a non-repeated sequence. [Figure 6] 11 is a schematic diagram of a frequency offset interval for a maximum synchronization point when receiving a preamble frame of a non-repeated sequence. [Figure 7] FIG. 2 is an illustration of a receiver algorithm based on FFT self-adaptation. [Figure 8] 1 is an example of M-FSK modulation, where M=8, the SCS is 2 kHz, and the symbol duration is 1 / 600 seconds or 600 sps (symbols per second). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention. Of course, the described embodiments are only some of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art under the premise of not performing creative labor, all belong to the scope of protection of the present invention.

[0027] The receiver and receiving method based on M-FSK modulation in the present application are corresponding receivers and receiving methods designed based on the advanced M-FSK transmission technology provided in patent applications 202011132046.0 and 202011402522.6, and the transmitter in the above application and the receiver in the present application jointly constitute an LPWAN technology based on advanced M-FSK. This application details a self-adaptive scalable receiver technology based on advanced M-FSK transmission, which has detection capability in low signal-to-noise ratio, anti-frequency offset capability, measurement technology, technology for multi-antenna synthesis to obtain energy and diversity gain, and scalable demodulation technology.

[0028] Before describing the receiver and receiving method based on M-FSK modulation provided by the present application, first, the transmitting side frame structure based on the M-FSK modulation technology (the present application refers to the self-adaptive or configurable M-FSK modulation transmission technology and the corresponding receiver technology as advanced M-FSK technology) of the present application is defined as follows: [Table 1]

[0029] Here, the preamble frame is used for frame detection and frame synchronization, the SYNC frame is used for data format establishment, and the data frame is transmitted adopting M-FSK coded or uncoded modulation, i.e., supporting different modulation and coding schemes. The preamble frame and the SYNC frame can be compatible with the conventional 2FSK or 2GFSK format (i.e., adopting 2FSK or 2GFSK modulation), and can also adopt a higher order modulation technique, i.e., the modulation order M=2n (n is an integer and n≧1) in the advanced M-FSK modulation technique realized in the present application. In addition, in order to reduce frequency spectrum leakage, the M-FSK modulation maintains phase continuity between symbols, i.e., M-CPFSK, and in order to further reduce frequency spectrum leakage, Gaussian filtering is added, i.e., M-GFSK, and M-FSK in the present application includes these two modulation methods.

[0030] The M-FSK modulation method is compatible with the conventional 2FSK or 2GFSK format, the preamble frame is transmitted using the conventional 2FSK or 2GFSK format, the SYNC code is modulated using 2FSK or 2GFSK, and the SYNC frame contains multiple types of modulation information. If the modulation information therein is the same as the conventional 2FSK or 2GFSK format, the Data frame is transmitted using the conventional 2FSK or 2GFSK format. If the modulation information therein is different, the frame structure of the Data frame is modulated and transmitted according to a predetermined format.

[0031] The modulation order M of the M-FSK modulation method is 2 or more, and the preamble frame, SYNC frame and data frame are modulated using the M-FSK format. Here, the format of the preamble frame or the sequence information to be transmitted differs from the conventional 2FSK or 2GFSK format, and specifically, may have any of the following formats.

[0032] 1 The Preamble code may be a repeating sequence, the minimum repeating granularity is N symbols, N≥2, and the number of all symbols of the Preamble code is an integer multiple of N.

[0033] 2 The Preamble code is a non-repeating m-sequence modulated using 2FSK or 2GFSK. Here, the m-sequence is an abbreviation for the maximum length linear shift register sequence. As the name indicates, the m-sequence is the longest code sequence generated by linear feedback using a multi-stage shift register or its delay element. In a binary shift register, if n is the number of stages of the shift register, the n-stage shift register has a total of 2^n states. Since all states except the all-0 state remain at 2^n - 1, the maximum length code sequence it can generate is 2^n - 1 bits.

[0034] 3 The Preamble code may be different from the conventional format, that is, it may not use M-FSK modulation. The Preamble supports the use of a CAZAC (Constant Amplitude Zero Auto Correlation) sequence. When adopting a Zadoff-Chu sequence, this sequence has constant amplitude characteristics and good correlation.

[0035] Example 1 Example 1 of the present application provides a receiving method based on M-FSK modulation. It adopts the M-FSK digital demodulation advanced receiver algorithm based on zero-IF shown in FIG. 1 and is realized based on the above M-FSK modulation transmission technology. As shown in FIG. 2, the receiving method based on the M-FSK modulation includes the following.

[0036] (1) Demodulate the Preamble frame The frame structure arrangements of both the transmitter and receiver, including the modulation order M and the sequence format of the preamble frame, are determined in advance. However, in the M-FSK modulation method of the transmitter, the preamble frame can be designed as a repeating sequence or a non-repeating sequence. Therefore, when demodulating in the receiver, appropriate demodulation processing must be performed on the preamble frame of a repeating sequence or a non-repeating sequence.

[0037] 1. If the preamble frame is a repeated sequence and each symbol adopts M-FSK modulation, the autocorrelation time-frequency synchronization technology is used to perform M-FSK demodulation of the preamble frame; Here, the time delay of the autocorrelation sequence is a multiple of the minimum number of repeated sequence symbols, the autocorrelation length is the sequence length minus the time delay of both autocorrelated sequences, the synchronization point is the preamble synchronization point to which the autocorrelation peak value point corresponds, and the frequency offset is determined based on the phase of the autocorrelation peak value position and the time delay of the two autocorrelated sequences.

[0038] Taking the repeated sequence of 2FSK modulation as an example, the reception of the preamble frame at the receiver is as shown in Figure 3. If the repeated sequence bits [1010.....10], total K bits, that is, the number of symbols in the preamble frame is K, and OSR (oversampling) is the sampling number of each symbol, the sequence length of the preamble frame at the transmitter is K*OSR. Since there is a symbol time delay in the frame structure transmission process, the sequence length of the autocorrelation preamble frame received at the receiver is (K-zz)*OSR. zz is the number of time delay symbols during autocorrelation, which is a multiple of the number of symbols of the minimum repetitive sequence, and its value ranges from 2 to K / 2. A new sequence Corr(k) is obtained by autocorrelation back and forth, where the preamble frame sequence changes from absent to present and then from present to absent, so the autocorrelation value gradually increases and then gradually decreases again. When the autocorrelation value is at its maximum and is greater than a certain threshold, that is, the complete preamble complete sequence has been received, and this time is the synchronization point of the preamble (Figure 4 is a schematic diagram of the relationship between the preamble frame sequence and the autocorrelation value).

[0039] At this time, the frequency offset calculated based on the phase estimate of the maximum correlation value width, the autocorrelation value, the number of time delay symbols, and the M-FSK symbol duration T is estimated as: CFO=phase(Corr(Kmax)) / (2π*(T*zz)), where phase represents the desired phase, and the phase is calculated based on multiple real and imaginary values; This application employs an autocorrelation time-frequency synchronization technique to detect preamble frames and perform time-frequency synchronization, thereby reducing the amount of calculation required to receive preamble frames.

[0040] 2 If the preamble frame is a non-repeating sequence (such as a pseudo-random sequence), the cross-correlation sliding FFT time-frequency synchronization technology is adopted to perform M-FSK demodulation of the preamble frame, where the non-repeating sequence includes the non-repeating sequence based on M-FSK sequence modulation, and is also suitable for other sequences or other modulation methods, such as CAZAC sequences and ZadoffChu sequences.

[0041] This application is based on the time-frequency synchronization technology of cross-correlation sliding FFT of non-repeated sequence preamble, and based on the sliding FFT method of receiving M-FSK modulation sequence and local sequence, the extensible local sequence (i.e., sampling rate is variable) acts to perform conjugate dot product with the received signal of the same sampling rate, and performs the function of deserialization information. Transform it into frequency domain, obtain the maximum value and frequency domain position information, obtain the correlation peak value at this time and the value for frequency offset estimation, compare the peak values ​​at different times, and if the maximum value of the peak value is greater than a certain threshold, that is, it is the time synchronization point of the preamble, and then obtain the frequency offset value according to the frequency domain position of the synchronization time point.

[0042] Taking the non-repeated sequence of 2FSK modulation as an example, the reception of the preamble frame by the receiver is as shown in Figure 5. If there are K 2-FSK preamble symbols, each symbol time length is T, and each symbol sampling number is OSR, then the sampling rate is T / OSR, and the local sequence length is K*OSR. t0, t1, t2... in Figure 5 are different sampling times, and the operation steps for each time are as follows: The preamble signal s(n) of the received sequence and the local sequence is properly zero-padded to an exponential length of 2 after several operations such as multiplication, thereby achieving the purpose of deserializing information, and is transformed into the frequency domain by FFT, and the width maximum value c(t(k)) and the corresponding frequency point position f(t(k)) are obtained in the frequency domain, where the time corresponding to the maximum point of the absolute value of the maximum value sequence of the frequency domain sequence is the synchronization time of the preamble, that is,

number

[0043] This application employs cross-correlation sliding FFT time-frequency synchronization technology to detect and synchronize preamble frames, which is insensitive to frequency offsets and can greatly improve the sensitivity of M-FSK detection and synchronization. At the same time, it has low detection sensitivity and can determine the allowable frequency offset over a relatively large range, which means that there is no need to use high crystal oscillation accuracy in the terminal.

[0044] (2) Adopting self-adaptive scalable FFT M-FSK data demodulation technology to perform M-FSK demodulation of SYNC frame and DATA frame, self-adaptation is based on three parameters, namely frequency point spacing SCS / symbol time length / number of modulation frequency points, to demodulate the transmitted symbols of scalable Advanced M-FSK, and self-adaptively demodulate the data demodulation based on M-FSK modulation to demodulate the SYNC frame and / or DATA frame.

[0045] In the embodiment of the present application, the demodulation method of the SYNC frame and the Data frame is the same, and both adopt the self-adaptive scalable FFT M-FSK data demodulation technology to perform demodulation. During subsequent decoding, different decoding methods can be adopted to perform decoding. However, what is mainly disclosed in the present application is the demodulation method, and the decoding method is not limited here.

[0046] The receiver described in this application adopts a receiver algorithm based on FFT self-adaptation, and determines the FFTSzie and the frequency point position according to the carrier spacing SCS and the symbol rate duration T through an appropriate sampling frequency Sampling Rate (SR), specifically including the following points:

[0047] 1 Signal bandwidth BW=SCS×2 K and the sampling frequency SR>=SCS×2 K The sampling frequency should be determined by the signal bandwidth. The higher the SR, the higher the noise immunity.

[0048] 2 The number of individual symbol sampling points is OSR = SR * T, and is padded to at least 2 by the zero padding method. K If the M-FSK symbol OSR value exceeds this number, the appropriate n to 2 is filled by the zero padding method. K ×2 nThe FFTSize is determined based on the sampling frequency SR and the symbol time length T, and the maximum frequency is selected. The biggest advantage of this method is that it obtains all the energy of M-FSK, and if OFDM has a cyclic prefix, it can remove the symbol energy one symbol before the M-FSK symbol to reduce the interference between symbols.

[0049] 3. Calculate based on the symbol time length T and carrier spacing SCS, and modulate the carrier position spacing SCSSize of the frequency points.

number

[0050] 4. Based on M, SCSSize and FFTSize, determine the position of the modulation frequency points, and in the frequency domain, only keep the values ​​of the modulation frequency points and set other values ​​to zero. Filtering.

[0051] 5. Compare the magnitude of the amplitude values ​​on the corresponding modulation frequency points, and the frequency point where the maximum energy is located is the modulation frequency point, and demodulate the modulated bit based on the frequency point. This method is hard decision. Due to the influence of noise, the difference between the maximum value of the modulation frequency point and the value of other frequency points is small, so the confidence interval of the demodulated bit can be calculated by the method of soft decision according to the value on each modulation frequency point.

[0052] Example calculation: parameters are SCS=7.5kHz; M=16 (i.e. K=4); T=1 / (4.8kHz).

[0053] According to the calculations, SR>=7.5*16=120kHz; SR=480kHz, OSR=SR*T=100; FFTSize=128; SCSSize=ceil(T*SCS)=2.

[0054] Based on M=16, FFTSize=128, and SCSSize=2, after the FFT shown in FIG. 7, the DC carrier is cycle-shifted to the center position FFTSize / 2+1=65, and the position of the modulation frequency point is at the (50:2:80) position.

[0055] This application adopts self-adaptive scalable FFT M-FSK data demodulation technology, which can obtain maximum likelihood detection performance and maximize all the energy of M-FSK symbols, and is especially suitable for demodulation of low-speed narrowband communication.

[0056] The above described process is relatively specific, but the important process is as follows:

[0057] The self-adaptive scalable FFT M-FSK data demodulation technology specifically adopts a receiver algorithm based on FFT self-adaptation, and determines the FFTSzie and frequency point position according to the carrier interval SCS and the symbol rate time length T by using the appropriate sampling frequency SR, specifically: determining a sampling frequency according to a signal bandwidth; determining an FFTSize based on a sampling frequency SR and a symbol time length T; Calculate based on the symbol time length T and the carrier interval SCS, and modulate the carrier position interval SCSSize of the frequency point; determining a position of a modulation frequency point based on M, SCSSize and FFTSize; demodulating the modulated bits based on the frequency points; Includes.

[0058] Example 2 In the second embodiment of the present application, M-FSK demodulation is performed on a frame structure including a preamble frame, a SYNC frame, and a Data frame. Specifically, When the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, the autocorrelation time-frequency synchronization technique is adopted to perform SNR detection and time-frequency synchronization of the preamble frame; when the preamble frame is a non-repetitive sequence, the cross-correlation sliding FFT time-frequency synchronization technique is adopted to perform SNR detection and time-frequency synchronization of the preamble frame; demodulating the preamble frame; Demodulating the SYNC frame and / or the DATA frame by adopting a self-adaptive scalable FFT M-FSK data demodulation technique to obtain maximum likelihood detection performance; The present invention further provides a receiving method based on M-FSK modulation, including:

[0059] This application provides a method for M-FSK energy detection and SNR measurement, which allows a receiver to obtain the corresponding receiving condition relatively accurately. Here, the energy calculation can use data symbols or preamble sequence symbols, and the peak value energy in the frequency domain is the energy of the desired signal. When using data symbols, the energy of the desired signal is the energy of the maximum energy value point in the frequency domain.

number

[0060] The present application provides a measurement technique for separating signal and noise in the frequency domain based on M-FSK or M-FSK modulation sequences, which can determine the signal energy and noise magnitude, respectively, and further calculate the magnitude of the signal-to-noise ratio, specifically: 1. Synchronizing the time point according to the non-repeated preamble sequence, the frequency domain peak value or the energy around the peak value of the deserialized information is the signal energy, and the other than the signal energy is the noise energy, and calculating the SNR according to the signal energy and the noise energy; 2. According to the M-FSK data symbol, after transforming into frequency domain, the total energy of the frequency domain peak value or the points near the peak value is the signal energy, and the frequency points other than the signal energy are the noise energy, and the SNR is calculated according to the signal energy and the noise energy; Includes.

[0061] Considering the energy leakage of the peak value, some frequency points around the peak value frequency point can be statistically calculated as the signal energy value, i.e.

number

number

[0062] Example 3 Embodiment 3 of the present application provides a method for realizing signal reception based on an M-FSK multi-antenna synthesis technology, which includes enabling the receiving side to obtain energy and diversity gain based on a multi-antenna synthesis technology where the peak value in the frequency domain serves as the correlation synthesis coefficient and / or based on a non-repeating sequence synchronization multi-antenna synthesis technology. The multi-antenna synthesis technology employs the maximum ratio synthesis method or the coherent synthesis method, and it can be performed in either the time domain or the frequency domain. Usually, in a communication system, a special pilot frequency symbol is required to estimate the corresponding antenna weight value in order to obtain the antenna weight coefficient. However, the present invention does not require any pilot frequency and can use only the M-FSK data symbols. These data symbols can be used for synthesizing different antenna data symbols, and an antenna synthesis coefficient can also be obtained using a pilot frequency sequence.

[0063] In the embodiment of the present application, data symbol demodulation synthesis is based on a multi-antenna synthesis technology where the peak value in the frequency domain serves as the correlation synthesis coefficient. Sampling is performed using a coherent or non-coherent synthesis method based on the synthesis of individual M-FSK symbols. The synthesis weight value of each antenna is the value that most greatly corresponds to all frequency points of the energy after the M-FSK symbol is converted into the frequency domain, or only retains the maximum value on the modulation frequency point. Based on the non-repeating sequence synchronization multi-antenna synthesis technology, sampling is performed using a coherent or non-coherent synthesis method, and the synthesis weight value of each antenna is the value that most greatly corresponds to the energy in the frequency domain of the M-FSK symbol.

[0064] Here, obtaining the antenna synthesis coefficient specifically includes the following sub-steps.

[0065] Step1, calculate the weight value.

[0066] The data symbol demodulation synthesis is a synthesis based on each M-FSK symbol, and the synthesis weight value of each antenna is the value that corresponds most to all the frequency points of the energy after the M-FSK symbol is transformed into the frequency domain, or the maximum value a on the modulation frequency point i e -jθ Only the maximum value obtained after modulating the frequency points is retained or filtered based on i e -jθ Based on the non-repetitive sequence synchronous multi-antenna synthesis technology, the synthesis weight value of each antenna is the value a i e -jθ It is.

[0067] Step 2: Calculate the compensation value.

[0068] The compensation value is the energy Ni of all points other than the maximum position and three points around it (which may be the energy calculated within 30 KHz), where Ni represents the energy of the i-th point.

[0069] Step 3: Calculate the compensation coefficient.

[0070] Antenna 0 is used as the reference, and the compensation coefficient

number

[0071] Step 4: Combine each antenna.

[0072] The resulting antenna synthesis coefficient is

number

number

[0073] Example 4 A fourth embodiment of the present application provides a receiver based on M-FSK modulation, which performs the methods of the first to third embodiments.

[0074] The above examples are merely specific embodiments of the present application, and are used to explain the technical solutions of the present application, but are not limitations thereon, and the scope of protection of the present application is not limited thereto. Although the present application has been described in detail with reference to the above examples, any person skilled in the art may still modify the technical solutions described in the above examples within the technical scope disclosed in the present application, or may easily come up with modifications, or may make equivalent substitutions for some of the technical features thereof, but such modifications, modifications or substitutions shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the examples of the present application. All of them shall be included in the scope of protection of the present application. Therefore, the scope of protection of the present application shall conform to the scope of protection of the claims.

Claims

1. When performing M-FSK demodulation on a frame structure including a preamble frame, a SYNC frame, and a Data frame, specifically, If the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, adopting autocorrelation time-frequency synchronization technology to perform M-FSK demodulation of the preamble frame; If the preamble frame is a non-repeated sequence, adopt the time-frequency synchronization technique of cross-correlation sliding FFT to perform M-FSK demodulation of the preamble frame; Employing self-adaptive scalable FFT M-FSK demodulation to perform M-FSK demodulation of the SYNC frame and the DATA frame; 2. A method of receiving based on M-FSK modulation, comprising:

2. The receiving method based on M-FSK modulation according to claim 1, characterized in that, when the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, the preamble frame sequence is autocorrelated with the previous and next to obtain a new sequence, and the synchronization point is determined based on satisfying a threshold value, and the autocorrelation peak value point is the corresponding preamble synchronization point, and when the autocorrelation value is maximum, it indicates that the complete preamble frame sequence has been received.

3. The frequency offset calculated based on the autocorrelation value of the maximum correlation value width, the number of time delay symbols zz, and the M-FSK symbol time length T is: CFO=phase(Corr(K ｍａｘ )) / (2π*(T*zz)), where phase represents the desired phase, the phase is calculated based on a complex number, and Corr(k) is a new sequence obtained by autocorrelating the preamble frame sequence with the preamble frame sequence.

4. A receiving method based on M-FSK modulation as described in claim 1, characterized in that when the preamble frame is a non-repeating sequence, the non-repeating sequence includes a non-repeating sequence based on M-FSK sequence modulation, is also suitable for other sequences or other modulation methods, and supports the use of CAZAC sequences and ZadoffChu sequences.

5. When the preamble frame is a non-repeated sequence, the time-frequency synchronization technology of cross-correlation sliding FFT is specifically based on the sliding FFT method of receiving the M-FSK modulation sequence and the local sequence, and the scalable local sequence is used to perform a conjugate dot product with the received signal of the same sampling rate, and performs the function of deserialization information, and transforms it into the frequency domain to obtain the maximum value and the position information of the frequency domain, and obtain the correlation peak value at this time and the value for frequency offset estimation, and compare the correlation peak values ​​at different times and the maximum value of the correlation peak value, and if it is greater than a certain threshold, that is, it is the time synchronization point of the preamble, and obtain the frequency offset value according to the frequency magnitude represented by the position of the frequency point at the synchronization time and the interval of the DC frequency point.

6. The receiving method based on M-FSK modulation as claimed in claim 1, characterized in that the self-adaptive scalable FFT M-FSK demodulation specifically demodulates the transmission symbol of scalable Advanced M-FSK according to the frequency point interval SCS / symbol time length / number of modulation frequency points, and demodulates the data demodulation based on M-FSK modulation in a self-adaptive manner.

7. The receiving method based on M-FSK modulation according to claim 1, characterized in that: based on multi-antenna combining technology, the frequency domain peak value is the correlation combining coefficient; the data symbol demodulation combining is based on each M-FSK symbol; and the combining weight value of each antenna is the value that corresponds most to all frequency points of the energy after the M-FSK symbol is transformed into the frequency domain, or only the maximum value on the modulation frequency point is kept.

8. A receiving method based on M-FSK modulation as described in claim 1, characterized in that when the preamble frame is a non-repeating sequence, based on synchronous multi-antenna synthesis technology, the synthesis weight value of each antenna is the value that corresponds most greatly to the energy in the frequency domain of the M-FSK symbol.

9. M-FSK demodulation is performed on a frame structure including a preamble frame, a SYNC frame, and a Data frame. Specifically, When the preamble frame is a repetitive sequence and each symbol adopts M-FSK modulation, adopt the time-frequency synchronization technique of autocorrelation to perform SNR detection and time-frequency synchronization of the preamble frame; when the preamble frame is a non-repetitive sequence, adopt the time-frequency synchronization technique of cross-correlation sliding FFT to perform SNR detection and time-frequency synchronization of the preamble frame; and M-FSK demodulate the preamble frame; M-FSK demodulation of the SYNC frame and the DATA frame is performed by adopting self-adaptive scalable FFT M-FSK demodulation to obtain maximum likelihood detection performance; 2. A method of receiving based on M-FSK modulation, comprising:

10. The receiving method based on M-FSK modulation as claimed in claim 9, characterized in that: based on multi-antenna combining technology, the frequency domain peak value is the correlation combining coefficient; the data symbol demodulation combining is based on each M-FSK symbol; and the combining weight value of each antenna is the value that corresponds most to all frequency points of the energy after the M-FSK symbol is transformed into the frequency domain, or only the maximum value on the modulation frequency point is kept.

11. A receiving method based on M-FSK modulation as described in claim 9, characterized in that when the preamble frame is a non-repeating sequence, based on synchronous multi-antenna synthesis technology, the synthesis weight value of each antenna is the value that corresponds most greatly to the energy in the frequency domain of the M-FSK symbol.

12. Specifically, the SNR detection and the time / frequency synchronization are performed as follows:

1. When the preamble frame is a non-repeated sequence, synchronize the time point based on the non-repeated preamble sequence, and the frequency domain peak value or the energy near the peak value of the deserialized information is the signal energy, and the other than the signal energy is the noise energy, and calculate the SNR based on the signal energy and the noise energy; 2. According to the M-FSK data symbol, after transforming into frequency domain, the total energy of the frequency domain peak value or points near the peak value is the signal energy, and the frequency points other than the signal energy are the noise energy, and the SNR is calculated according to the signal energy and the noise energy; A receiving method based on M-FSK modulation according to claim 9, characterized in that it comprises:

13. A receiver based on M-FSK modulation, characterized in that the receiver comprises implementing a method for receiving an M-FSK modulated signal according to any one of claims 1 to 12.

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