CN112615643A - Receiving end signal capturing method and related equipment used in large frequency offset state - Google Patents
Receiving end signal capturing method and related equipment used in large frequency offset state Download PDFInfo
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- H—ELECTRICITY
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- H04B1/69—Spread spectrum techniques
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Abstract
One or more embodiments of the present disclosure provide a method and related apparatus for capturing a signal at a receiving end in a large frequency offset state, where the method divides a large frequency offset range into a plurality of continuous estimated frequency offset ranges; mixing a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal; capturing the converted pilot frequency signal to obtain a capture value, if the capture value is not lower than a preset capture threshold, determining that the capture is successful, calculating to obtain a small-range frequency offset value in the estimated frequency offset range, and correcting the local compensation carrier in a small range. Under the condition of successful capture, only a small-range frequency offset value needs to be calculated, the small-range frequency offset value is far smaller than the carrier overall frequency offset value, and the shift value of the local pseudo code signal relative to the pilot signal is also greatly reduced, so that the single calculation amount in the capture stage is greatly reduced, and the smooth operation of the capture stage is facilitated.
Description
Technical Field
One or more embodiments of the present disclosure relate to the field of carrier synchronization technologies, and in particular, to a method for capturing a signal at a receiving end in a large frequency offset state and a related device.
Background
In a wireless communication system, signals are exposed in a wireless space and are easily affected by doppler shift, multipath attenuation, co-channel interference and the like, local oscillator clocks of a transmitting end and a receiving end of the communication system are not completely consistent, a local oscillator circuit is unstable, and unknown carrier frequency difference and unknown phase deviation exist in the received signals due to the multi-factor factors. High-rate, high-reliability and high-security signal communication is premised on accurate synchronization of wireless transmission systems, wherein carrier synchronization is one of the important factors affecting receiver performance. One of the purposes of the receiving end is to implement carrier synchronization on the received signals through a series of methods, so that the receiving end can accurately receive the required baseband signals to complete accurate communication. The process of receiving signals by a receiving end can be divided into two parts of acquisition and tracking: firstly, capturing a local carrier which is mainly used for correcting and receiving signal frequency mixing by using a carrier frequency offset value, and then capturing a pilot signal; secondly, tracking is to calculate the frequency offset value of the pilot signal in real time in the process of tracking the pilot signal in real time, further modify the local carrier mixed with the received signal, and output a baseband signal.
The capture method most commonly used today is a parallel code phase capture method based on Fast Fourier Transform (FFT), which currently has two main problems: (1) in the method, in the process of capturing the pilot signal, the local pseudo code after resampling and the pilot signal need to be circularly convolved (namely frequency domain shift multiplication) on a time domain, when the local pseudo code signal is aligned with the pilot signal, the circular convolution value is maximum, the shift value of conjugate data after local pseudo code FFT is positively correlated with the carrier frequency offset value, the larger the carrier frequency offset value of large frequency offset in the existing process of capturing the pilot signal is, the higher the shift value is, the larger the calculation amount is, and the smooth implementation of the capturing process is not facilitated. (2) When the pseudo code pilot frequency auxiliary receiving technical method is applied, compared with a local pseudo code signal, a baseband signal is equivalent to a noise signal, so that the bandwidth of a low-pass filter determines the quality of the capturing performance, namely the bandwidth of the low-pass filter is narrowed to be beneficial to improving the capturing performance.
Disclosure of Invention
In view of this, one or more embodiments of the present disclosure provide a method and a related apparatus for acquiring a signal at a receiving end in a large frequency offset state, so as to solve the problems of a large calculation amount of an intermediate frequency offset value and a wide bandwidth of a low pass filter in the prior art.
In view of the above, one or more embodiments of the present specification provide a receiving-end signal acquisition method in a large frequency offset state, including:
dividing a large frequency deviation range into a plurality of continuous estimated frequency deviation ranges, taking the middle value of each estimated frequency deviation range as the estimated offset corresponding to the estimated frequency deviation range, and taking the sum of the estimated offset and the local carrier frequency as the frequency of a local compensation carrier;
mixing a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
filtering the down-converted signal by using a narrow-band low-pass filter to filter most of baseband signals and reserve pilot signals;
performing analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter;
capturing the converted pilot frequency signal to obtain a capture value, if the capture value is not lower than a preset capture threshold, determining that the capture is successful, calculating to obtain a small-range frequency offset value in the estimated frequency offset range, and correcting the local compensation carrier in a small range.
Based on the same inventive concept, one or more embodiments of the present specification further provide a receiving end signal capturing apparatus in a large frequency offset state, including:
the setting module is used for dividing a large frequency deviation range into a plurality of continuous estimated frequency deviation ranges, taking the middle value of each estimated frequency deviation range as the estimated offset corresponding to the estimated frequency deviation range, and taking the sum of the estimated offset and the local carrier frequency as the frequency of a local compensation carrier;
the compensation down-conversion module is configured to mix a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
a filtering module configured to filter the down-converted signal using a narrow-band low-pass filter to filter out most of the baseband signal while retaining a pilot signal;
the conversion module is used for carrying out analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter; and the capturing module is configured to capture the converted pilot frequency signal to obtain a captured value, if the captured value is not lower than a preset capturing threshold, the capturing is determined to be successful, a small-range frequency offset value in the estimated frequency offset range is calculated, and the local compensation carrier is corrected in a small range.
Based on the same inventive concept, one or more embodiments of the present specification further provide an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable by the processor, wherein the processor implements the above method when executing the computer program.
Based on the same inventive concept, one or more embodiments of the present specification also provide a non-transitory computer-readable storage medium storing computer instructions which, when executed by a computer, cause the computer to implement the above-described method.
As can be seen from the foregoing, in one or more embodiments of the present disclosure, a receiving end signal capturing method and related apparatus for use in a large frequency offset state are provided, where a receiving signal received by a receiving end is mixed with a local compensation carrier to perform down-conversion, where a frequency of the local compensation carrier is a sum of a local carrier frequency of the receiving end and an estimated offset; firstly, a pre-estimated frequency deviation range is given, the carrier generator directly sends out a local compensation carrier after the local carrier frequency is added with the intermediate value (pre-estimated offset) of the pre-estimated frequency deviation range, if the capturing is successful, the pre-estimated frequency deviation range is correct, a small-range frequency deviation value is obtained by calculation and then returned to correct the local compensation carrier, and the frequency of the corrected local compensation carrier (i.e. the carrier integral frequency deviation value) is the sum of the local carrier frequency of a receiving end, the pre-estimated offset and the small-range frequency deviation value; namely, under the condition of successful capture, only a small-range frequency offset value needs to be calculated, the small-range frequency offset value is far smaller than the carrier overall frequency offset value, and the shift value of the local pseudo code signal relative to the pilot signal is also greatly reduced, so that the single calculation amount in the capture stage is greatly reduced, and the smooth operation of the capture stage is facilitated.
Drawings
In order to more clearly illustrate one or more embodiments or prior art solutions of the present specification, the drawings that are needed in the description of the embodiments or prior art will be briefly described below, and it is obvious that the drawings in the following description are only one or more embodiments of the present specification, and that other drawings may be obtained by those skilled in the art without inventive effort from these drawings.
Fig. 1 is a flowchart illustrating a QPSK modulation scheme applied to a transmitting end in one or more embodiments of the present disclosure;
fig. 2 is a spectrum diagram of a synthesized baseband signal i (n) according to one or more embodiments of the present disclosure;
fig. 3 is a flowchart illustrating a method for acquiring a pilot signal at a receiving end according to one or more embodiments of the present disclosure;
FIG. 4 is a functional block diagram of an FFT-based parallel code phase acquisition method in accordance with one or more embodiments of the present disclosure;
fig. 5 is a schematic diagram illustrating resampling of a pilot signal and a local pseudo-code signal at a receiving end according to one or more embodiments of the present disclosure;
FIG. 6 is a search diagram when N is 400 in one or more embodiments of the disclosure;
FIG. 7(a), FIG. 7(b), and FIG. 7(c) are graphical representations of the location of correlation peaks a, b, c, respectively, of one or more embodiments of the present disclosure;
fig. 8 is a schematic block diagram of a receiving-end pilot signal acquisition process apparatus according to one or more embodiments of the present disclosure;
fig. 9 is a hardware configuration diagram of an electronic device according to one or more embodiments of the present disclosure.
Detailed Description
For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.
It is to be noted that unless otherwise defined, technical or scientific terms used in one or more embodiments of the present specification should have the ordinary meaning as understood by those of ordinary skill in the art to which this disclosure belongs.
As described in the background art, the larger the carrier frequency offset value of the large frequency offset in the existing pilot signal capturing process is, the higher the local pseudo code signal shift value is, the larger the calculation amount is, which is not favorable for the smooth implementation of the capturing process. Specifically, in the prior art, the received signal received by the receiving end is directly mixed with the local carrier for down-conversion to obtain a down-converted signal, because the received signal of the receiving end related to the present invention is a large frequency offset signal (megahertz and above, such as 1MHz, 2MHz, 3MHz, 4MHz, …, 20MHz, etc.), and the shift value of the conjugate data after local pseudo code FFT is positively correlated with the carrier frequency offset value, with the maximum frequency offset value Δ f of the carriermaxFor example, 20MHz is used, the local pseudo code signal shift value involved in the acquisition stage is up to 2000, and the corresponding calculation amount is also large (4001 data needs to be calculated), which is not favorable for the smooth implementation of the acquisition process.
Aiming at the technical problem, the invention discloses a carrier synchronization capturing method under the state of large frequency offset, and the invention is characterized in that a sending end divides a baseband signal into I, Q paths, a low-power spreading code pseudo-random sequence pilot frequency (pilot frequency signal for short) is inserted into an I path, signals of I, Q paths respectively pass through a digital-to-analog converter DAC, I, Q paths of analog signals output by the DAC are respectively subjected to analog orthogonal frequency mixing with a high-frequency carrier, then, signals after orthogonal frequency mixing are subjected to orthogonal modulation of I, Q paths of analog signals, and the signals after orthogonal frequency mixing are sent to a wireless channel by an antenna.
After a wireless signal received by an antenna passes through a low noise amplifier by a receiving terminal, the signal received by the receiving terminal is also divided into I, Q paths, after analog orthogonal frequency mixing is carried out on I, Q paths of signals and a local compensation carrier (namely the sum of the local carrier and a median of an estimated frequency deviation range), the I, Q paths of signals after analog frequency mixing are filtered by a narrow-band low-pass filter, most baseband signals are filtered, and a pilot signal is reserved; and capturing the pilot signal after the low-speed analog-to-digital converter (ADC), if the capturing is successful, indicating that the estimated frequency offset range is correct, calculating to obtain a small-range frequency offset value, and correcting the local compensation carrier frequency during the frequency mixing of the receiving end by using the calculated small-range frequency offset value of the carrier wave to finish the capturing process.
As an alternative embodiment, referring to fig. 1, the transmitting end signaling process includes:
a transmitting end inserts a low-power spread spectrum Code Pseudo-random sequence pilot frequency (Pseudo-Noise Code, hereinafter referred to as pilot signal or PN) into a baseband signal to obtain a combined baseband signal;
enabling the combined baseband signal to pass through a digital-to-analog converter (DAC), and enabling the DAC to output an analog signal to perform analog quadrature mixing with a high-frequency carrier;
the mixed signal is transmitted to a wireless channel.
Further, referring to fig. 1, the transmitting end may use a Quadrature Phase Shift Keying (QPSK) modulation scheme with good noise immunity and frequency band utilization, that is, the transmitting end signal transmitting process includes:
a transmitting end divides a baseband signal into I, Q paths and inserts a pilot signal into an I path;
passing the I, Q two paths of signals through a digital-to-analog converter (DAC), and performing analog quadrature mixing on I, Q two paths of analog signals output by the DAC and a high-frequency carrier respectively;
and (3) carrying out quadrature modulation on the I, Q two paths of analog signals, and sending the quadrature-modulated signals to a wireless channel by an antenna.
In the figure ID(n) and QD(n) is a transmission frequency RsThe base band signal to be transmitted, PN (n) is pilot signal with good autocorrelation, and the transmitting end only inserts the pilot signal into the I path signal, the transmission frequency of the pilot signal is Rc_pnThe pilot signal corresponding to the modulation signal has a frequency of RbAnd R isc_pn＜＜RbThe pilot signal frequency is much less than the baseband data signal frequency so that the pilot does not significantly change the signal waveform when inserted into the baseband signal. Combination of Chinese herbsThe spectrum of the baseband signal i (n) is shown in fig. 2.
As an alternative embodiment, referring to fig. 3, the receiving end signal acquisition process includes:
s301, dividing a large frequency deviation range into a plurality of continuous estimated frequency deviation ranges, taking the middle value of each estimated frequency deviation range as the estimated offset corresponding to the estimated frequency deviation range, and taking the sum of the estimated offset and the local carrier frequency as the frequency of a local compensation carrier;
s302, mixing a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
s303, filtering the down-conversion signal by using a narrow-band low-pass filter to filter most of baseband signals and reserve pilot signals;
s304, performing analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter;
s305, capturing the converted pilot frequency signal to obtain a capture value, if the capture value is not lower than a preset capture threshold, determining that the capture is successful, calculating to obtain a small-range frequency offset value in the estimated frequency offset range, and correcting the local compensation carrier in a small range.
Further, the capturing the converted pilot frequency signal to obtain a captured value, if the captured value is not lower than a preset capture threshold, determining that the capturing is successful, calculating to obtain a small-range frequency offset value within the estimated frequency offset range, and correcting the local compensation carrier in a small range, including:
utilizing a parallel code phase capturing method, taking the estimated offset as a center, searching and calculating a correlation result peak value of the pilot frequency signal and the local pseudo code signal in a time domain in a forward and backward search mode within an estimated frequency offset range where the estimated offset is located, if the correlation result peak value is higher than a set capturing threshold, successfully capturing, and calculating to obtain a local pseudo code signal shift value and the small-range frequency offset value within the estimated frequency offset range; wherein the local pseudo code shift value is used to substantially align the local pseudo code signal with the pilot signal, and the small range offset value is used to return to modify a local compensation carrier;
if the correlation result peak value is lower than the capture threshold, repeating the following operations until the correlation result peak value is determined not to be lower than the capture threshold: and switching to the next estimated frequency offset range, and performing the front and back search calculation in the next estimated frequency offset range by using a parallel code phase capturing method.
And the frequency of the local pseudo code signal is the same as that of a pilot signal of a transmitting end.
In this embodiment, to solve the above problem, a received signal received by a receiving end is mixed with a local compensation carrier to perform down-conversion, where the frequency of the local compensation carrier is the sum of a local carrier frequency of the receiving end and an estimated offset; that is, a pre-estimated frequency deviation range is given, the carrier generator directly sends out a local compensation carrier after the local carrier frequency is added with the intermediate value of the pre-estimated frequency deviation range, if the acquisition is successful, the pre-estimated frequency deviation range is correct, and a small-range deviation value obtained by calculation is returned to correct the local compensation carrier.
That is, the frequency of the corrected local compensation carrier (i.e., the carrier overall frequency offset value) is the sum of the local carrier frequency of the receiving end, the estimated offset and the small-range frequency offset value. And under the condition of successful capture, only a small-range frequency offset value needs to be calculated, wherein the small-range frequency offset value is far smaller than the carrier overall frequency offset value, and the shift value of the local pseudo code signal relative to the pilot signal is also greatly reduced, so that the single calculation amount in the capture stage is greatly reduced, and the smooth operation of the capture stage is facilitated.
In addition, the large frequency offset range is confirmed as follows: when the receiving end and the transmitting end both use the first cosmic velocity v1When the two move reversely at 7.9km/s, the relative movement of the two reaches the maximum vmax＝2v12 × 7.9km/s is 15.8km/s, so the maximum frequency deviation is:
therefore, the frequency offset range required to be captured by the capturing method described in this embodiment is [ - | Δ f [ ]max|,|Δfmax|]I.e. maximum carrier frequency offset of deltafmaxIs 17MHz as high as +/-8.5 MHz, isSo that the maximum frequency offset can be searched and captured, at least B is required to be satisfied1≥Rc_pn+|Δfmax18.73MHz, where B1Is a narrow band low pass filter bandwidth, Rc_pnFor local pseudo-code signal rate, Rc_pnFor the fixed value, the present embodiment takes 10.23MHz, which is commonly used in the analog simulation process, as an example; in the actual operation process, in order to ensure that the maximum frequency offset can be searched and captured, the actual maximum carrier frequency offset is expanded to delta fmax20MHz, i.e. in this case B1≥20.23MHz。
The bandwidths of 18.73MHz and 20.23MHz are large, which causes the noise of the pilot signal passing through the low-pass filter to be too large, and is not favorable for capturing the pilot signal.
In order to solve the above technical problem, as an optional embodiment, the large frequency offset range [ -10MHz ] is divided into a plurality of estimated frequency offset ranges which are continuously set, and each estimated frequency offset measures a middle value of each estimated frequency offset range.
Further, if the absolute value of the difference between the head and tail values of the estimated frequency deviation range is used as the step value (Δ f) of the estimated frequency deviation rangestepThen each step value (Δ f) of the estimated frequency deviation rangestepThe estimated frequency deviation ranges can be the same or different, and the plurality of continuously arranged estimated frequency deviation ranges only need to cover the whole large frequency deviation range (delta f)stepMay be specifically one of 1MHz, 2MHz, 4MHz and 5 MHz. For ease of calculation, the step value (Δ f) is estimated for each frequency offset rangestepSame and (Δ f)step4MHz for example, [ -10MHz to 10MHz]The estimated frequency offset range and the estimated offset are shown in Table 1, i.e., (Δ f)step＝Δfmax＝4MHz，
The bandwidth of the narrow band low pass filter may be narrowed 1/3 to reduce the noise of the pilot signal passing through the low pass filter, which facilitates the acquisition of the pilot signal.
TABLE 1 estimated frequency deviation Range and estimated offset for each acquisition
It should be noted that, in the capturing stage, the pilot signal is mainly captured, so that the QPSK data baseband signal is equivalent to a noise signal, and the narrowing of the bandwidth of the narrow-band low-pass filter reduces the portion of the QPSK data baseband signal within the passband of the filter, so that the narrowing of the bandwidth of the low-pass filter is beneficial to improving the performance of capturing the pilot signal.
As an alternative embodiment, an FFT-based parallel code phase acquisition algorithm may be employed.
The functional block diagram of the implementation of the FFT-based parallel code phase acquisition method is shown in fig. 4. After the received signal is mixed with sine carrier and cosine carrier of local compensation carrier of I branch and Q branch, the pilot signal of each branch is filtered out through a narrow-band low-pass filter, Fast Fourier Transform (FFT) is carried out on complex signal I + jq and the complex signal is multiplied by FFT conjugate of local pseudo code signal, then a module value is obtained after the multiplication result is subjected to Inverse Fast Fourier Transform (IFFT), finally a correlation result peak value of the pilot signal and the local pseudo code signal on a time domain is obtained by searching in an estimated frequency deviation range where estimated offset is located, and finally the correlation value is compared with a set capture threshold. When the correlation value is higher than the capture threshold value, successfully capturing to obtain a shift value and a small-range frequency offset value of the local pseudo code signal, feeding back the obtained small-range frequency offset value and correcting the local compensation carrier, adjusting the phase of the local pseudo code signal according to the shift value of the local pseudo code signal to enable the phase to be basically aligned with the pilot signal, finishing the capture link, and then entering a tracking link; and when the correlation value is lower than the acquisition threshold value, switching to the next frequency search range to continue searching, namely shifting the FFT value of the pilot signal, and repeating the process until the whole frequency range is searched.
Specifically, the FFT-based parallel code phase acquisition algorithm process is represented as follows:
x(n)＝i(n)+j·q(n) (1)
z(n)＝abs{IFFT{FFT[x(n)]×FFT*[PN(n)}}} (2)
because the uncertain receiving end receives the initial value of the signal code phase, in order to ensure that the signal to be processed contains a complete pseudo code sequence, the embodiment selects the 2-bit data length to carry out the correction of the code phase and the frequency offset estimation. With a frequency of 2Rc_pnThe downconverted filtered I, Q signals are resampled individually by a 20.46MHz clock to obtain 4092 points of data each. Meanwhile, oversampling is carried out for 2 times on the pseudo code sequence in a period, and 2046 point data is obtained. When the FFT capture algorithm is adopted, it can be known from formula (2) that the number of points for performing FFT on the resampled signal and the 2-fold oversampled PN code respectively needs to be a power of 2, so that 40 s need to be complemented for data, 2050 s need to be complemented for PN code, and 4096 points need to be complemented respectively (i.e. 2 points are complemented for PN code12) And then FFT is respectively carried out.
In the acquisition process, a visual diagram of the local pseudo code signal and the filtered pilot signal after resampling is shown in fig. 5.
And circularly convolving the local pseudo code after resampling and zero padding with the filtered pilot signal time domain (namely frequency domain shift multiplication). Here, the filtered pilot signal is fixed after FFT, and the local pseudo code FFT-backed conjugate data is shifted to the left and right by N bits, respectively, and if the acquired search frequency range is to be satisfied, the shift value N needs to be determined by the following formula:
wherein, Δ RfRepresenting the frequency value interval on the FFT frequency axis, namely the FFT frequency resolution; f. ofsIs the sampling frequency; n is a radical offftThe number of FFT points. With fs＝2Rc_pn＝20.46MHz，Nfft＝4096，(Δf)stepAs calculated by equation (3) and equation (4), Δ R, for example, at 4MHzf0.005MHz, N400; in the prior art, the large frequency deviation range is not split, and Δ f in the above embodimentmax＝(Δf)stepFor example, when the frequency offset is 20MHz, N is 2000 (4001 segments of data need to be calculated once), which is obviously larger than the shift value obtained by splitting the large frequency offset range in the present embodiment, that is, the local pseudo code signal shift value in the technical scheme of the present embodiment, which divides the large frequency offset range into a plurality of continuously set estimated frequency offset ranges, is small, and the calculation amount is small, thereby facilitating the smooth operation of the capturing process.
When N is 400, the search within a certain estimated frequency offset range is shown in fig. 6.
After the local pseudo code signal FFT, conjugate data are respectively shifted back and forth by 400, and then, data with 0 bit (namely, data which is not moved back and forth) are added, so that 801 sections of data need to be calculated once.
The local pseudo code signal sequence is circularly shifted, and is subjected to correlation operation with the pilot signal at different positions, and the occurrence positions of correlation peaks are illustrated in fig. 7(a), 7(b), and 7 (c).
When the local pseudo code signal is circularly shifted, three positions are all obvious peak values. When the local pseudo code shift state is the local pseudo code 1, the local pseudo code signal sequence 2046 point is completely aligned with the whole data of the pilot signal sequence, and the correlation peak value is highest at the moment; when the local pseudo code signal shift state is local pseudo code 2, only the front (2050-x) points of the local pseudo code signal sequence are aligned with the front (2046-x) points of the next section of data of the pilot signal sequence, although a correlation peak also appears, the correlation peak value is obviously lower than the correlation peak a; when the local pseudo code shift state is a local pseudo code 3, aligning a rear x point of a local pseudo code signal sequence with a rear x point of a segment of data on a pilot signal sequence to generate a correlation peak c, wherein the correlation peak is obviously lower than a correlation peak a because only part of data are aligned; wherein the data bits of the correlation peak b and the correlation peak c are different by only 4 bits.
Comparing the correlation peak value of each shift with the capture threshold, if the correlation peak value is higher than the detection capture threshold, judging that the capture is successful, observing the occurrence position of the corresponding highest correlation peak, namely the maximum peak appears at which shift point, and marking as NmaxThen through NmaxCalculating a small-range frequency offset value delta fSmall rangeThe specific calculation process is as follows:
Δfsmall range＝Nmax·ΔRf
To obtain the estimated frequency deviation range of [6MHz, 10MHz ]]For example, if the capture is successful, which estimates the offset to be 8, if the maximum peak is reached at bit 0 (no motion) and the maximum peak is above the threshold, then Δ f Small range0, 0.005, that is, the carrier integral frequency offset value is 8; if the maximum peak is obtained at 200 bits (200 bits shifted backward), Δ fSmall range200 × 0.005 ═ 1MHz, that is, the carrier overall frequency offset value is 8+1 ═ 9 MHz.
Based on the same inventive concept, corresponding to any of the above embodiments, with reference to fig. 8, one or more embodiments of the present specification further provide a receiving end signal synchronization apparatus in a large frequency offset state, including:
the setting module 801 divides a large frequency deviation range into a plurality of estimated frequency deviation ranges which are continuously set, takes a middle value of each estimated frequency deviation range as an estimated offset, and takes the sum of the estimated offset and a local carrier frequency as the frequency of a local compensation carrier;
a compensation down-conversion module 802 configured to mix a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
a filtering module 803 configured to filter the down-converted signal by using a narrow-band low-pass filter to filter most of the baseband signal and to retain the pilot signal;
a conversion module 804, which performs analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter;
an acquiring module 805 configured to acquire the converted pilot signal to obtain an acquisition value, determine that the acquisition is successful if the acquisition value is not lower than a preset acquisition threshold, calculate a small-range frequency offset value within the estimated frequency offset range, and correct the local compensation carrier in a small range.
For convenience of description, the above devices are described as being divided into various modules by functions, and are described separately. Of course, the functionality of the modules may be implemented in the same one or more software and/or hardware implementations in implementing one or more embodiments of the present description.
The apparatus in the foregoing embodiment is used to implement a corresponding method for acquiring a signal at a receiving end in a large frequency offset state in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiment, which are not described herein again.
Based on the same inventive concept, corresponding to the method of any embodiment described above, one or more embodiments of the present specification further provide an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement the method for capturing a signal at a receiving end in a large frequency offset state according to any embodiment described above.
Fig. 9 is a schematic diagram illustrating a more specific hardware structure of an electronic device according to this embodiment, where the electronic device may include: a processor 1010, a memory 1020, an input/output interface 1030, a communication interface 1040, and a bus 1050. Wherein the processor 1010, memory 1020, input/output interface 1030, and communication interface 1040 are communicatively coupled to each other within the device via bus 1050.
The processor 1010 may be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an Application Specific Integrated Circuit (ASIC), or one or more Integrated circuits, and is configured to execute related programs to implement the technical solutions provided in the embodiments of the present disclosure.
The Memory 1020 may be implemented in the form of a ROM (Read Only Memory), a RAM (Random Access Memory), a static storage device, a dynamic storage device, or the like. The memory 1020 may store an operating system and other application programs, and when the technical solution provided by the embodiments of the present specification is implemented by software or firmware, the relevant program codes are stored in the memory 1020 and called to be executed by the processor 1010.
The input/output interface 1030 is used for connecting an input/output module to input and output information. The i/o module may be configured as a component in a device (not shown) or may be external to the device to provide a corresponding function. The input devices may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output devices may include a display, a speaker, a vibrator, an indicator light, etc.
The communication interface 1040 is used for connecting a communication module (not shown in the drawings) to implement communication interaction between the present apparatus and other apparatuses. The communication module can realize communication in a wired mode (such as USB, network cable and the like) and also can realize communication in a wireless mode (such as mobile network, WIFI, Bluetooth and the like).
It should be noted that although the above-mentioned device only shows the processor 1010, the memory 1020, the input/output interface 1030, the communication interface 1040 and the bus 1050, in a specific implementation, the device may also include other components necessary for normal operation. In addition, those skilled in the art will appreciate that the above-described apparatus may also include only those components necessary to implement the embodiments of the present description, and not necessarily all of the components shown in the figures.
The electronic device of the foregoing embodiment is used to implement a corresponding method for capturing a signal at a receiving end in a large frequency offset state in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiment, which are not described herein again.
Based on the same inventive concept, corresponding to any of the above embodiments, one or more embodiments of the present specification further provide a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute a receiving-end signal acquisition method in a large frequency offset state according to any of the above embodiments.
Computer-readable media of the present embodiments, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), Read Only Memory (ROM), Electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), Digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device.
The computer instructions stored in the storage medium of the foregoing embodiment are used to enable the computer to execute the method for acquiring a signal at a receiving end in a large frequency offset state according to any of the foregoing embodiments, and have the beneficial effects of corresponding method embodiments, which are not described herein again.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the spirit of the present disclosure, features from the above embodiments or from different embodiments may also be combined, steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present description as described above, which are not provided in detail for the sake of brevity.
In addition, well-known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown in the provided figures, for simplicity of illustration and discussion, and so as not to obscure one or more embodiments of the disclosure. Furthermore, devices may be shown in block diagram form in order to avoid obscuring the understanding of one or more embodiments of the present description, and this also takes into account the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the one or more embodiments of the present description are to be implemented (i.e., specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that one or more embodiments of the disclosure can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative instead of restrictive.
While the present disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic ram (dram)) may use the discussed embodiments.
It is intended that the one or more embodiments of the present specification embrace all such alternatives, modifications and variations as fall within the broad scope of the appended claims. Therefore, any omissions, modifications, substitutions, improvements, and the like that may be made without departing from the spirit and principles of one or more embodiments of the present disclosure are intended to be included within the scope of the present disclosure.
Claims (10)
1. A receiving end signal capturing method used in a large frequency offset state is characterized by comprising the following steps:
dividing a large frequency deviation range into a plurality of continuous estimated frequency deviation ranges, taking the middle value of each estimated frequency deviation range as the estimated offset corresponding to the estimated frequency deviation range, and taking the sum of the estimated offset and the local carrier frequency as the frequency of a local compensation carrier;
mixing a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
filtering the down-converted signal by using a narrow-band low-pass filter to filter most of baseband signals and reserve pilot signals;
performing analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter;
capturing the converted pilot frequency signal to obtain a capture value, if the capture value is not lower than a preset capture threshold, determining that the capture is successful, calculating to obtain a small-range frequency offset value in the estimated frequency offset range, and correcting the local compensation carrier in a small range.
2. The method of claim 1,
the large frequency deviation range is [ -10MHz ].
3. The method of claim 1 or 2, wherein the sum of the estimated offset and the small-range frequency offset value is within the estimated frequency offset range corresponding to the estimated offset.
4. The method of claim 3, wherein each of the plurality of successive ranges of estimated frequency offsets has a same step value, and the step value is an absolute value of a difference between a leading value and a trailing value of the range of estimated frequency offsets.
5. The method of claim 4, wherein the bandwidth of the narrow-band low-pass filter is greater than or equal to the sum of the transmission frequency of the pilot signal and one half of the step value.
6. The method of claim 1 or 2, wherein the acquiring the transformed pilot signal to obtain an acquisition value comprises:
and utilizing a parallel code phase capturing method, taking the estimated offset as a center, and searching and calculating a correlation result peak value of the pilot frequency signal and the local pseudo code signal in a time domain in a pre-estimated frequency offset range corresponding to the estimated offset to be used as the capturing value.
7. The method of claim 6, further comprising:
if the correlation result peak value is lower than the capture threshold, repeating the following operations until the correlation result peak value is determined not to be lower than the capture threshold: and switching to the next estimated frequency offset range, and performing the front and back search calculation in the next estimated frequency offset range by using a parallel code phase capturing method.
8. A receiving end signal capturing apparatus in large frequency offset state, comprising:
the setting module is used for dividing a large frequency deviation range into a plurality of continuous estimated frequency deviation ranges, taking the middle value of each estimated frequency deviation range as the estimated offset corresponding to the estimated frequency deviation range, and taking the sum of the estimated offset and the local carrier frequency as the frequency of a local compensation carrier;
the compensation down-conversion module is configured to mix a received signal received by a receiving end with the local compensation carrier to obtain a down-conversion signal;
a filtering module configured to filter the down-converted signal using a narrow-band low-pass filter to filter out most of the baseband signal while retaining a pilot signal;
the conversion module is used for carrying out analog-to-digital conversion on the pilot signal by using a low-speed analog-to-digital converter; and the capturing module is configured to capture the converted pilot frequency signal to obtain a captured value, if the captured value is not lower than a preset capturing threshold, the capturing is determined to be successful, a small-range frequency offset value in the estimated frequency offset range is calculated, and the local compensation carrier is corrected in a small range.
9. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable by the processor, wherein the processor implements the method of any of claims 1-7 when executing the computer program.
10. A non-transitory computer-readable storage medium storing computer instructions which, when executed by a computer, cause the computer to implement the method of any one of claims 1 to 7.
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