Carrier frequency offset position detection method, device, equipment and backscatter communication system

Abstract

The application provides a carrier frequency offset position detection method, device and equipment and a backscattering communication system, and belongs to the technical field of backscattering communication. A signal is received; the signal is a superimposed signal of a carrier signal and a backscattering signal obtained by modulating to-be-sent data on the carrier signal; the received signal is demodulated into a digital baseband signal; the digital baseband signal is taken modulo after direct current removal; whether the carrier frequency offset exists is judged; if the carrier frequency offset exists, the frequency offset position is calculated. The application can detect the existing position of the carrier frequency offset without a pilot, the data processing is simple, only needs to accumulate and calculate the data obtained by sampling, and has important significance for improving the performance of backscattering communication.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of backscatter communication, and particularly relates to a carrier frequency offset position detection method, device and equipment and a backscatter communication system. BACKGROUND

[0002] Backscatter communication technology is one of the key technologies of future Internet of Things. Its working principle is that sensors or tags obtain energy by using wireless signals and communicate by using backscatter, thereby getting rid of the shackles of batteries and avoiding frequent manual maintenance operations. At the same time, since backscatter communication does not need to generate a carrier radio frequency signal, it does not need an active radio frequency component, thereby reducing the cost of sensors. Zero power consumption, low cost and easy maintenance are important features of backscatter communication technology.

[0003] In a backscatter communication system, due to the influence of factors such as differences in physical environment such as temperature and humidity, relative motion of the transmitting and receiving ends, and crystal oscillator precision, carrier frequency offset (CFO) may exist between the receiving end and the transmitting end in the actual signal transmission process. Carrier frequency offset will affect the orthogonality of subcarriers, thereby causing inter-carrier interference and seriously affecting system performance. CFO has an important influence on signal detection and system performance, and current most passive backscatter communication system research ignores CFO. SUMMARY

[0004] The present application aims to provide a carrier frequency offset position detection method, device and equipment and a backscatter communication system without pilot-based detection of the existence of carrier frequency offset position, to solve at least one of the technical problems in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] On the one hand, the present application provides a backscatter communication carrier frequency offset position detection method, comprising:

[0007] receiving a signal; the signal is a superimposed signal of a carrier signal and a backscatter signal after modulating the data to be sent onto the carrier signal;

[0008] demodulating the received signal into a digital baseband signal;

[0009] taking the modulus after removing the direct current of the digital baseband signal;

[0010] judging whether the carrier frequency offset exists, and if it exists, calculating the frequency offset position.

[0011] Preferably, the received signal is demodulated into a digital baseband signal is:

[0012] ;

[0013] wherein, denotes the signal after carrier signal demodulation, denotes the signal after backscattering signal demodulation, denotes the time, is the carrier frequency offset, is the noise, is the carrier signal frequency, is the initial phase, is the natural constant.

[0014] Preferably, the removing DC and then taking modulus of the digital baseband signal comprises:

[0015] sampling the signal, the sampled signal being:

[0016] wherein, is the sampling period, is the number of sampling points;

[0017] then removing DC and then taking modulus of the signal:

[0018] wherein, is the modulus operator.

[0019] Preferably, the judging whether the carrier frequency offset exists comprises:

[0020] obtaining the sampled data , and solving the cumulative sum of the obtained data, the cumulative sum being:

[0021] ;

[0022] wherein, is the data average value, and the obtained cumulative sum data is expressed as ;

[0023] then calculating the maximum difference of the cumulative sum variation amplitude of the original data :

[0024] ;

[0025] wherein, ;

[0026] then randomly sorting the data to obtain N sorting manners, the data after a certain sorting being , and the new cumulative sum being ;

[0027] then, the maximum difference of the cumulative sum variation amplitude of the data of each sorting manner is:

[0028] ; wherein , , ;

[0029] calculating the number C of the orderings in N orderings satisfying

[0030] then:

[0031] ;

[0032] if =1, it indicates that there is a carrier frequency offset; otherwise, there is not; is a confidence level.

[0033] Preferably, the frequency offset position is calculated.

[0034] ; wherein, represents the index value of the maximum value in the parentheses.

[0035] In a second aspect, the present application provides a device for detecting the carrier frequency offset position in backscatter communication, comprising:

[0036] a receiving module, configured to receive a signal; the signal is a superimposed signal of a carrier signal and a backscatter signal after modulating to-be-sent data onto the carrier signal;

[0037] a demodulating module, configured to demodulate the received signal into a digital baseband signal;

[0038] a processing module, configured to take a modulus after removing direct current from the digital baseband signal;

[0039] a judging module, configured to judge whether the carrier frequency offset exists, and if it exists, calculate the frequency offset position.

[0040] In a third aspect, the present application provides a backscatter communication system, comprising:

[0041] a first device, configured to generate a carrier signal with a center frequency;

[0042] a second device, in communication connection with the first device, configured to receive the carrier signal generated by the first device, and emit a backscatter signal after modulating to-be-sent data onto the carrier signal;

[0043] ​​A third device, in communication with the first device and the second device, receives a superimposed signal of the carrier signal transmitted by the first device and the backscatter signal transmitted by the second device, demodulates the received signal into a digital baseband signal, removes DC from the digital baseband signal, and determines whether a carrier frequency offset exists and, if so, calculates the location of the frequency offset.

[0044] In a fourth aspect, the present application provides a non-transitory computer readable storage medium for storing computer instructions, which, when executed by a processor, implement the backscatter communication carrier frequency offset location detection method as described above.

[0045] In a fifth aspect, the present application provides a computer program product comprising a computer program which, when run on one or more processors, is configured to implement the backscatter communication carrier frequency offset location detection method as described above.

[0046] In a sixth aspect, the present application provides an electronic device comprising a processor, a memory, and a computer program, wherein the processor is connected to the memory, and the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory to cause the electronic device to execute instructions for implementing the backscatter communication carrier frequency offset location detection method as described above.

[0047] The present application has the advantages of detecting the location of the carrier frequency offset without pilot signals, simple data processing, and only needing to accumulate and calculate the sampled data, which is of great significance to improving the performance of backscatter communication.

[0048] The advantages of the additional aspects of the present application will be more apparent from the following description or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0050] Fig. 1 is a schematic diagram of a backscatter communication carrier frequency offset location detection system according to an embodiment of the present application.

[0051] Fig. 2 is a schematic diagram of a backscatter communication carrier frequency offset location detection system according to an embodiment of the present application.

[0052] Figure 3 is a simulation diagram of the theoretical and detection curves of the method for detecting the carrier frequency offset position of the backscatter communication system according to the embodiment of the present application.

[0053] Figure 4 is a flow chart of the method for detecting the carrier frequency offset position of the backscatter communication system according to the embodiment of the present application. DETAILED DESCRIPTION

[0054] The embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments of the present application described below are examples and are used to explain the present application, but should not be construed as limiting the embodiments of the present application.

[0055] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0056] It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined herein.

[0057] Those skilled in the art can understand that, unless otherwise stated, the singular forms "a", "an" and "the" used herein also include the plural forms. It should be further understood that the use of the phrase "comprises" in the specification of the present application means that the features, integers, steps, operations, elements and / or groups thereof are present, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or groups thereof.

[0058] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0059] In order to facilitate the understanding of the present application, the present application is further explained and described in specific embodiments below with reference to the accompanying drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present application.

[0060] Those skilled in the art should understand that the drawings are only schematic views of embodiments and that the components in the drawings do not necessarily have to be present in the embodiments of the present application.

[0061] Embodiment 1

[0062] In this embodiment 1, a carrier frequency offset position detection device is provided first, comprising:

[0063] A receiving module is configured to receive a signal; the signal is a superimposed signal of a carrier signal and a backscattering signal after modulating to-be-sent data onto the carrier signal;

[0064] A demodulating module is configured to demodulate the received signal into a digital baseband signal;

[0065] A processing module is configured to take a modulus after removing direct current from the digital baseband signal;

[0066] A judging module is configured to judge whether the carrier frequency offset exists, and if so, calculate the frequency offset position.

[0067] In this embodiment 1, the carrier frequency offset position detection method is realized by using the above device, comprising:

[0068] The receiving module is used to receive a signal; the signal is a superimposed signal of a carrier signal and a backscattering signal after modulating to-be-sent data onto the carrier signal; the demodulating module is used to demodulate the received signal into a digital baseband signal; the processing module is used to take a modulus after removing direct current from the digital baseband signal; and the judging module is used to judge whether the carrier frequency offset exists, and if so, calculate the frequency offset position.

[0069] The received signal is demodulated into a digital baseband signal , which is:

[0070] ;

[0071] wherein, denotes the signal after demodulating the carrier signal, denotes the signal after demodulating the backscattering signal, denotes the time point, is the carrier frequency offset, is the noise, is the carrier signal frequency, is the initial phase, is a natural constant.

[0072] Taking a modulus after removing direct current from the digital baseband signal comprises:

[0073] Sampling the signal, and the sampled signal is:

[0074] ; wherein is the sampling period, is the number of sampling points;

[0075] Then the signal is de-DC and moduled:

[0076] ; wherein, is the modulo operator.

[0077] Judging whether the carrier frequency offset exists, comprising:

[0078] Obtaining the sampled data , and solving the cumulative sum of the obtained data, the cumulative sum being:

[0079] ;

[0080] wherein is the data average value, and the cumulative sum data is expressed as ;

[0081] Then the maximum difference of the cumulative sum change amplitude of the original data is calculated :

[0082] ;

[0083] wherein ;

[0084] Then the data is randomly sorted to obtain N sorting modes, the data after a certain sorting being , and the new cumulative sum being ;

[0085] The maximum difference of the cumulative sum change amplitude of the data of each sorting mode is :

[0086] ; wherein , , ;

[0087] The number C of the sorting modes in the N sorting modes satisfying < is calculated;

[0088] Then:

[0089] ;

[0090] If =1, it is indicated that the carrier frequency offset exists; otherwise, it does not exist; is the confidence level.

[0091] Calculating the frequency offset position is:

[0092] ; wherein, denotes the index value of the maximum value in the brackets.

[0093] Embodiment 2

[0094] In this embodiment 2, a backscatter communication system is provided, which comprises:

[0095] a first device for generating a carrier signal of a center frequency;

[0096] a second device, which is in communication connection with the first device, for receiving the carrier signal generated by the first device and transmitting a backscatter signal after modulating the data to be sent onto the carrier signal;

[0097] and a third device, which is in communication connection with the first device and the second device, for receiving the superimposed signal of the carrier signal transmitted by the first device and the backscatter signal transmitted by the second device; demodulating the received signal into a digital baseband signal; taking the modulus after removing the direct current from the digital baseband signal; and judging whether the carrier frequency offset exists, and if so, calculating the frequency offset position.

[0098] In the first device, a transmitting unit is provided, which is used for transmitting the generated carrier signal; the second device has a micro-processing unit with a crystal oscillator to support backscatter communication, which is used for receiving the carrier signal generated by the first device and transmitting the backscatter signal after modulating the data to be sent onto the carrier signal; the third device has a receiving unit and a processing unit, wherein the receiving unit is used for receiving the signal and demodulating it into a digital baseband signal; the processing unit is used for processing the demodulated signal, including detecting whether the carrier frequency offset exists. Specifically, in the third device, the receiving unit is used for receiving the signal; the signal is the superimposed signal of the carrier signal and the backscatter signal after modulating the data to be sent onto the carrier signal; the processing unit includes a demodulation module, a processing module and a judgment module, the demodulation module is used for demodulating the received signal into a digital baseband signal; the processing module is used for taking the modulus after removing the direct current from the digital baseband signal; and the judgment module is used for judging whether the carrier frequency offset exists, and if so, calculating the frequency offset position.

[0099] In this embodiment 2, the communication method of the above backscatter communication system is:

[0100] Step one: the first device transmits a carrier signal to the second device and the third device;

[0101] Step two: the second device modulates the data to be sent onto the carrier signal and backscatters the signal to the third device;

[0102] Step three: the third device sends the received signal sent by the first device and the signal backscattered by the second device into the processing unit after demodulation, takes the modulus after removing the direct current of the signal, and judges whether the carrier frequency offset exists between the first device and the third device and the second device according to the algorithm;

[0103] Step four: the third device processing unit judges whether the carrier frequency offset exists according to the judgment result, if it exists, detects the backscattered signal to detect the position where the carrier frequency offset exists.

[0104] Among them, the received signal is demodulated into a digital baseband signal , is:

[0105] ;

[0106] Among them, indicates the signal after demodulation of the carrier signal, indicates the signal after demodulation of the backscattered signal, indicates the time, is the carrier frequency offset, is the noise, is the carrier signal frequency, is the initial phase, is a natural constant.

[0107] Taking the modulus after removing the direct current of the digital baseband signal includes:

[0108] Sampling the signal, the sampled signal is:

[0109] ; wherein is the sampling period, is the number of sampling points;

[0110] Then taking the modulus after removing the direct current of the signal:

[0111] ; wherein, is the modulus operator.

[0112] Judging whether the carrier frequency offset exists includes:

[0113] Obtaining the sampled data , obtaining the cumulative sum of the data, the cumulative sum is:

[0114] ;

[0115] Among them is the average value of the data, and the cumulative sum data is represented as ;

[0116] Then the maximum difference of the cumulative sum and the change amplitude of the original data is calculated :

[0117] ;

[0118] wherein ;

[0119] Then the data is randomly sorted to obtain N sorting methods, and the data after a certain sorting is , and the new cumulative sum is ;

[0120] The maximum difference of the cumulative sum and the change amplitude of the data of each sorting method is :

[0121] ; wherein , , ;

[0122] The number C of sorting methods satisfying is calculated.

[0123] Then:

[0124] ;

[0125] If =1, it indicates that the carrier frequency offset exists; otherwise, it does not exist. is the confidence level.

[0126] The frequency offset position is calculated:

[0127] ; wherein represents the index value of the maximum value in the parentheses.

[0128] Embodiment 3

[0129] In this embodiment 3, a backscattering communication system is provided, in which a backscattering communication carrier frequency offset position detection method is designed, which can quickly detect whether the carrier frequency offset exists without pilot, and find the position where the frequency offset exists. The third device described in the system can judge whether the carrier frequency offset of the second device exists and the position where the carrier frequency offset exists through calculation, and can meet the communication demand of backscattering in different application scenarios.

[0130] Specifically, the backscattering communication system comprises a first device, a second device and a third device, wherein: the first device is used for generating a carrier signal with a center frequency; the second device is used for receiving the carrier signal and scattering the signal back; and the third device is used for receiving the carrier signal and the scattered signal​

[0131] The first device is provided with a transmitting unit, and the third device is provided with a receiving unit and a processing unit, wherein: the transmitting unit is used for transmitting a carrier signal; the receiving unit is used for receiving a signal and demodulating it into a digital baseband signal; and the processing unit is used for processing the demodulated signal, including judging whether a carrier frequency offset exists. The second device supports backscatter communication.

[0132] In the system, the carrier frequency offset position detection method is as follows:

[0133] Step 1: The first device transmits a carrier signal to the second device and the third device.

[0134] Step 2: The second device modulates the data to be transmitted onto the carrier signal and backscatters the signal to the third device.

[0135] Step 3: The third device demodulates the signal received from the first device and the signal backscattered by the second device, sends the demodulated signal into the processing unit, removes direct current from the signal, takes a modulus of the signal, and judges whether a carrier frequency offset exists between the first device and the third device and the second device according to the algorithm.

[0136] Step 4: The third device processing unit judges whether a carrier frequency offset exists according to the judgment result, and if it exists, detects the position of the carrier frequency offset.

[0137] The signal received by the third device is the superposition of the carrier signal emitted by the first device and the signal reflected by the second device. The demodulated signal received by the third device is represented by formula (1):

[0138] ; (1)

[0139] Wherein, represents the demodulated signal of the carrier signal, represents the demodulated signal of the backscattered signal, represents the time, is the carrier frequency offset, is the noise, is the carrier signal frequency, is the initial phase, is a natural constant.

[0140] On the basis of the above scheme, in step 3, the third device demodulates the signal and sends it into the processing unit. The sampled signal is represented by formula (2):

[0141] ; (2)

[0142] Wherein is a sampling period, is a sampling point number.

[0143] Then, the signal is de-DC and modulated to obtain a processed signal, which is represented by formula (3):

[0144] ; (3)

[0145] wherein, is a mod operator.

[0146] On the basis of the above scheme, the third device detects the position of the carrier frequency offset according to the judgment result of whether the carrier frequency offset exists or not, including: obtaining the sampled data , and solving the cumulative sum of the obtained data, which is represented by formula (4):

[0147] ; (4)

[0148] wherein is a data average value, and the cumulative sum data is represented as ;

[0149] Then, the maximum difference of the cumulative sum change amplitude of the original data is calculated , which is represented by formula (5):

[0150] ; (5)

[0151] wherein ;

[0152] Then, the data is randomly sorted to obtain N sorting methods, and the data after a certain sorting is , and the new cumulative sum is obtained according to formula (4);

[0153] The maximum difference of the cumulative sum change amplitude of the data of each sorting method is calculated according to formula (6) as follows:

[0154] ; wherein , , ; The number C of sorting methods that satisfy

[0155] in N sorting methods is calculated; The third device obtains the result of judging whether the carrier frequency offset exists or not according to the algorithm according to formula (7), that is:

[0156] ​​

[0157] (7)

[0158] like =1 indicates that a carrier frequency offset exists; otherwise, it does not exist. The confidence level.

[0159] exist When the value is 1, meaning a carrier frequency offset exists, the detection algorithm is used to detect the position of the first occurrence of the carrier frequency offset. It can be expressed by formula (8):

[0160] (8)

[0161] in, Indicates the index of the maximum value within the parentheses.

[0162] The backscatter communication carrier frequency offset position detection system and method provided in this embodiment allows the third device to detect the location of the carrier frequency offset without pilot signals. The data processing is simple, requiring only the accumulation and calculation of the sampled data. This provides a new carrier frequency offset position detection scheme, which is of great significance for improving the performance of backscatter communication.

[0163] Example 4

[0164] In backscatter communication systems, it is considered that carrier frequency offset (CFO) may exist between the receiver and transmitter during actual signal transmission. To detect the existence and location of carrier frequency offset, this embodiment designs a general carrier frequency offset location detection method.

[0165] First, the third device demodulates the superposition of the carrier signal sent by the first device and the signal reflected by the second device. Second, the third device samples the demodulated signal and uses the proposed algorithm to determine if a carrier frequency offset exists. Finally, based on the determination of the carrier frequency offset, if a carrier frequency offset exists, the third device detects the location of the first occurrence of the carrier frequency offset.

[0166] like Figure 1 The backscatter communication system shown includes:

[0167] The device comprises a first device, a second device, and a third device; both the first and second devices are equipped with a transmitting unit, and the third device includes a receiving unit and a processing unit.

[0168] The first device is configured to generate a carrier signal, the transmitting unit is configured to modulate a digital baseband signal and transmit the modulated signal to space, the second device is configured to receive the carrier signal and modulate data to be transmitted onto the carrier signal and backscatter the signal to the third device, the receiving unit of the third device is configured to receive the signal transmitted by the first device and the signal backscattered by the second device and demodulate the signal, and the processing unit is configured to determine whether a carrier frequency offset exists and detect the position of the carrier frequency offset according to the determination result.

[0169] As shown in the backscattering communication system, Figure 2 the first device and the third device are configured to generate a carrier signal, modulate a digital baseband signal and transmit the modulated signal to space, receive the signal transmitted by the first device and the signal backscattered by the second device and demodulate the signal, and determine whether a carrier frequency offset exists and detect the position of the carrier frequency offset according to the determination result; and the second device is configured to receive the carrier signal, modulate data to be transmitted onto the carrier signal and backscatter the signal to the third device.

[0170] The backscattering communication system works as follows: the first device implements a transmitter function and is configured to generate a transmitting radio frequency, the second device is configured to receive and modulate a signal and modulate the signal in a backscattering mode to obtain a backscattering signal transmitted to the third device, and the third device receives the superposition of the signal transmitted by the first device and the signal backscattered by the second device, demodulates the signal and sends the signal to the processing unit.

[0171] As shown in the backscattering communication system, Figure 4 a backscattering communication carrier frequency offset position detection method includes the following steps:

[0172] Step 1: The first device transmits a carrier signal to the second device and the third device.

[0173] Step 2: The second device modulates data to be transmitted onto the carrier signal and backscatters the signal to the third device.

[0174] Step 3: The third device demodulates the signal received by the first device and the signal backscattered by the second device and sends the signal to the processing unit, removes direct current from the signal, takes a modulus of the signal, and determines whether a carrier frequency offset exists between the first device and the third device and the second device according to the algorithm.

[0175] Step 4: The third device determines whether a carrier frequency offset exists according to the determination result, and if a carrier frequency offset exists, detects the position of the carrier frequency offset.

[0176] On the basis of the above scheme, the signal received by the third device is the superposition of the carrier signal emitted by the first device and the signal reflected by the second device. The receiving unit of the third device obtains the signal after demodulation of the received signal , samples the signal, and the sampling period is ;

[0177] On the basis of the above scheme, after the third device sends the demodulated signal into the processing unit in step three, the signal is first sampled, and the signal after the direct current removal and modulo operation of the signal is obtained by formula (3) , , wherein is the number of sampling points, and in the embodiment, it is assumed that is 100; the third device divides the processed signal into two parts: a carrier frequency offset exists and a carrier frequency offset does not exist , and it is assumed that ;

[0178] The fourth step is that the third device detects the position of the carrier frequency offset according to the judgment result of whether the carrier frequency offset exists, and includes the following steps.

[0179] Obtain the sampled data , and obtain the cumulative sum of the 100 data, and the cumulative sum data is represented as ;

[0180] Calculate the maximum difference of the cumulative sum change amplitude of the original data by formula (4) , randomly sort the data to obtain N sorting methods, and set N=1000; the data after a certain sorting is , Obtain the new cumulative sum according to formula (5) ;

[0181] Calculate the maximum difference of the cumulative sum change amplitude of the data of each sorting method by formula (6) : the number of samples that satisfy in the 1000 samples is C=957;

[0182] The third device judges whether the carrier frequency offset exists by formula (7) , takes , and obtains , so it is judged that the carrier frequency offset exists.

[0183] The processing unit of the third device detects the result of the position of the carrier frequency offset according to the detection algorithm, that is, the position of the first occurrence of the carrier frequency offset.​

[0184] Theoretical and detection curve simulation diagram of the carrier frequency offset position detection obtained by using the application in different positions of the frequency offset is shown in the following figure: Figure 3

[0185] In the simulation, the samples of the signal obtained after processing are simulated, wherein is the number of samples when the carrier frequency offset exists; is the number of samples when the carrier frequency offset does not exist. It can be seen from the following figure that: 1) the detection position increases with the increase of the value, and the relationship is linear. 2) the detected carrier frequency offset position is basically consistent with the theoretical analysis result. It can be considered that the method can effectively solve the problem of carrier frequency offset position detection. Figure 3

[0186] Embodiment 5

[0187] Embodiment 5 provides a non-transitory computer readable storage medium for storing computer instructions, which, when executed by a processor, implements the carrier frequency offset position detection method for backscatter communication as described above, which comprises:

[0188] receiving a signal; the signal is a superimposed signal of a carrier signal and a backscatter signal after modulating to-be-sent data on the carrier signal;

[0189] demodulating the received signal into a digital baseband signal;

[0190] taking a modulus after removing direct current from the digital baseband signal;

[0191] judging whether the carrier frequency offset exists, and if it exists, calculating the frequency offset position.

[0192] Embodiment 6

[0193] Embodiment 6 provides a computer program product comprising a computer program, which, when running on one or more processors, is used to implement the carrier frequency offset position detection method for backscatter communication as described above, which comprises:

[0194] receiving a signal; the signal is a superimposed signal of a carrier signal and a backscatter signal after modulating to-be-sent data on the carrier signal;

[0195] demodulating the received signal into a digital baseband signal;

[0196] taking a modulus after removing direct current from the digital baseband signal;

[0197] judging whether the carrier frequency offset exists, and if it exists, calculating the frequency offset position. ​​​

[0198] Embodiment 7

[0199] Embodiment 7 provides an electronic device, comprising: a processor, a memory and a computer program; wherein the processor is connected with the memory, and the computer program is stored in the memory; when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes instructions for realizing the backscattering communication carrier frequency offset position detection method as described above, which comprises:

[0200] receiving a signal; the signal is a superimposed signal of a carrier signal and a backscattering signal after the to-be-sent data is modulated on the carrier signal;

[0201] demodulating the received signal into a digital baseband signal;

[0202] taking a modulus after removing direct current from the digital baseband signal;

[0203] judging whether the carrier frequency offset exists, and if so, calculating the frequency offset position.

[0204] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0205] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 an apparatus that carries out the functions specified in one or more flows and / or blocks.

[0206] These computer program instructions can also be stored in a computer-readable memory capable of guiding the computer or other programmable data processing devices to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including instruction apparatus, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1the function specified in the one or more blocks.

[0207] These computer program instructions can also be loaded into computer or other programmable data processing devices, to cause a series of operational steps to be performed on the computer or other programmable data processing devices, so that the computer program instructions which execute on the computer or other programmable data processing devices provide steps for implementing the function specified in the flowchart block or blocks. Figure 1 the function specified in the one or more blocks. Figure 1 the function specified in the one or more blocks.

[0208] The above description is only a specific implementation of the present application, and is not a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications or changes can be made to the disclosed technical solutions without requiring inventive labor, and all such modifications or changes should be covered within the scope of protection of the present application.

Claims

1. A method of carrier frequency offset position detection, the method comprising: Comprising: receiving a signal; the signal is a superimposed signal of a carrier signal and a backscattering signal after modulating to-be-sent data onto the carrier signal; demodulating the received signal into a digital baseband signal; After the digital baseband signal is removed from direct current, the modulus is obtained ; judging whether a carrier frequency offset exists, and if so, calculating the frequency offset position; wherein judging whether the carrier frequency offset exists comprises: Obtain the sampled data , for the obtained Calculate the cumulative sum from the given data points. The cumulative sum is: ； wherein is the average value of the data, the cumulative sum data is represented as ; Then the maximum difference of the accumulated sum and the amplitude of change of the original data is calculated first : ； wherein ; Then the data is randomly sorted to obtain N kinds of sorting, the data after a certain sorting is , and the new cumulative sum is ; Then, the maximum difference of the cumulative sum and the change range of the data of each sorting manner is: ; wherein , , ; Calculate the number of permutations C that satisfy ​​ then: ； If = 1, it indicates that there is a carrier frequency offset; otherwise, there is not; is a confidence level; Computing the frequency offset position : ; wherein, denotes the index value of the maximum in the parentheses.

2. The carrier frequency offset position detection method of claim 1, wherein, demodulating the received signal into a digital baseband signal for: ； wherein, denotes the demodulated signal of the carrier signal, denotes the demodulated signal of the backscatter signal, denotes the time instant, is the carrier frequency offset, is the noise, is the carrier signal frequency, is the carrier signal, is the natural constant.

3. The carrier frequency offset position detection method of claim 2, wherein, taking a modulus after removing direct current from the digital baseband signal comprises: sampling the signal, and the sampled signal is: ; wherein is a sampling period, is a number of sampling points; then taking a modulus after removing direct current from the signal: ; wherein, is a modulo operator.

4. A carrier frequency offset position detection apparatus characterized by comprising: comprising: a receiving module, configured to receive a signal; the signal is a superimposed signal of a carrier signal and a backscattering signal after modulating to-be-sent data onto the carrier signal; a demodulating module, configured to demodulate the received signal into a digital baseband signal; The processing module is configured to perform modulo operation on the digital baseband signal after removing direct current to obtain ; a judging module, configured to judge whether a carrier frequency offset exists, and if so, calculate the frequency offset position; wherein judging whether the carrier frequency offset exists comprises: acquiring the sampled data solving the cumulative sum of the obtained data, the cumulative sum being ； wherein is the average value of the data, the cumulative sum data is represented as ; Then the maximum difference of the accumulated sum and the amplitude of change of the original data is calculated first : ； wherein ; Then the data is randomly sorted to obtain N sorting methods, the data after a certain sorting is , and the new cumulative sum is ; Then, the maximum difference of the cumulative sum and the change range of the data of each sorting manner is: ; wherein , , ; Calculate the number of permutations C that satisfy in N permutations​ then: ； If = 1, it indicates that there is a carrier frequency offset; otherwise, there is not; is a confidence level; Computing the frequency offset position : ; wherein, denotes the index value of the maximum in the parentheses.

5. A backscatter communication system, characterized by comprising: a first device, configured to generate a carrier signal with a center frequency; a second device, in communication connection with the first device, configured to receive the carrier signal generated by the first device, and emit a backscattering signal after modulating to-be-sent data onto the carrier signal; A third device, in communication with the first device and the second device, for receiving a superimposed signal of the carrier signal transmitted by the first device and the backscatter signal transmitted by the second device; demodulating the received signal into a digital baseband signal; taking a modulo of the digital baseband signal after removing a direct current to obtain ​ judging whether a carrier frequency offset exists, and if so, calculating the frequency offset position; wherein judging whether the carrier frequency offset exists comprises: acquiring the sampled data solving the cumulative sum of the obtained data, the cumulative sum being ； wherein is the average value of the data, the cumulative sum data is represented as ; Then the maximum difference of the accumulated sum and the amplitude of change of the original data is calculated first : ； wherein ; Then the data is randomly sorted to obtain N sorting methods, the data after a certain sorting is , and the new cumulative sum is ; Then, the maximum difference of the cumulative sum and the change range of the data of each sorting manner is: ; wherein , , ; Calculate the number of permutations C that satisfy in N permutations​ then: ； If = 1, it indicates that there is a carrier frequency offset; otherwise, there is not; is a confidence level; Computing the frequency offset position : ; wherein, denotes the index value of the maximum in the parentheses.

6. A non-transitory computer-readable storage medium, comprising: the non-transitory computer readable storage medium is configured to store computer instructions, which are executed by a processor to implement the carrier frequency offset position detection method according to any one of claims 1-3.

7. A computer program product, characterised in that, comprising a computer program, which, when running on one or more processors, is configured to implement the carrier frequency offset position detection method according to any one of claims 1-3.

8. An electronic device, comprising: comprising: a processor, a memory and a computer program; wherein the processor is connected with the memory, and the computer program is stored in the memory; when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes instructions for implementing the carrier frequency offset position detection method according to any one of claims 1-3.

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