CN115801517A - Carrier processing method based on air-ground combined interference system and related equipment - Google Patents
Carrier processing method based on air-ground combined interference system and related equipment Download PDFInfo
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Abstract
The invention relates to the technical field of communication interference, and discloses a carrier processing method based on an air-ground combined interference system and related equipment, which are used for realizing carrier modulation and demodulation, synchronization, carrier frequency deviation estimation, carrier channel equalization and peak-to-average ratio reduction processing, so that an ad hoc network has the characteristics of strong multipath fading resistance, strong interference resistance, high frequency utilization rate and suitability for high-speed data transmission. The method comprises the following steps: in the transmitter part, according to the transmission data required by different sending rates, the carrier wave of the transmission data is correspondingly modulated by using BPSK, QPSK, 16QAM or 64QAM modulation modes, and all the modulated mappings are normalized; in the receiver part, a complex signal containing in-phase and orthogonal components is received, and when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation, a corresponding code element is judged to be recovered original transmission data.
Description
Technical Field
The present invention relates to the field of communication interference technologies, and in particular, to a carrier processing method and related devices based on an air-ground joint interference system.
Background
In order to meet the requirements of an air-ground combined interference system, the air-ground combined networking is interconnected in a wireless ad hoc network mode, the wireless ad hoc network does not depend on the existing fixed communication network infrastructure, the topological structure is flexible to change, the survivability is strong, and the requirements of the special field on quick expansion, flexible networking, strong survivability, good mobility, no time and space limitation and the like of the communication network can be well met.
Considering the complex electromagnetic environment application scenario of the air-ground combined interference system, the system is easily affected by factors such as electromagnetic environment, natural weather, communication distance and the like, and faces certain risks in safety and reliability. In order to effectively solve the problem of multipath fading resistance, the invention realizes data transmission by using OFDM (Orthogonal Frequency Division Multiplexing) in the air-ground combined interference system, and realizes modulation and demodulation of data by using a digital signal processor so as to reduce the problem related to multipath in the wireless channel. Because the capacity of the communication path in the ad hoc network system for transmitting data changes along with time, namely time-varying, OFDM can dynamically adapt to the ad hoc network, and can almost completely overcome the intersymbol interference caused by multipath, and the method is particularly suitable for the multi-user distributed ad hoc network of an air-ground combined interference system.
The invention provides a carrier processing method based on an air-ground combined interference system, which is used for realizing carrier modulation and demodulation, carrier synchronization, carrier frequency deviation estimation, carrier channel equalization and peak-to-average ratio reduction processing, so that an ad hoc network has the characteristics of strong multipath fading resistance, strong anti-interference capability, high frequency utilization rate and suitability for high-speed data transmission.
Disclosure of Invention
The invention provides a carrier processing method and related equipment based on an air-ground combined interference system, which are used for realizing carrier modulation and demodulation, carrier synchronization, carrier frequency deviation estimation, carrier channel equalization and peak-to-average ratio reduction processing, so that an ad hoc network has the characteristics of strong multipath fading resistance, strong interference resistance, high frequency utilization rate and suitability for high-speed data transmission.
In order to achieve the above object, a first aspect of the present invention provides a carrier processing method based on an air-ground joint interference system, including:
in the transmitter part, according to the transmission data required by different sending rates, correspondingly using BPSK, QPSK, 16QAM or 64QAM modulation modes to modulate the carrier waves of the transmission data, and normalizing all modulated mappings;
in the receiver part, a complex signal containing in-phase and orthogonal components is received, and when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation, a corresponding code element is judged to be recovered original transmission data.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in the transmitter section, a pilot signal is inserted in the frequency domain of the modulated carrier spectrum as a carrier synchronization signal, and transmission data is converted from frequency to a time domain signal by fast fourier transform;
in the receiver part, a carrier synchronization signal subjected to pilot frequency is received, a time domain signal is converted into a frequency domain signal through fast Fourier transform, the pilot frequency is extracted according to the frequency domain signal, carrier frequency deviation is estimated through the pilot frequency, and the received signal is compensated in the time domain according to the carrier frequency deviation.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the estimating a carrier frequency offset through the pilot specifically includes:
a wide range of carrier frequency offset estimates, including integer carrier frequency offsets, is performed using the acquisition mode and a fine carrier frequency offset estimate is performed using the tracking mode.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
at a transmitter portion, embedding a specific training symbol in the transmission data in advance;
in the receiver portion, to estimate the frequency response of the channel, each data symbol in the carrier is channel estimated and equalized using the received training symbols.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in a receiver part, whether the current frequency spectrum is used by equipment is known by periodically sensing frequency points in a certain frequency band range, and the frequency points which are not interfered are recorded;
and detecting whether a preset Ad hoc network link interruption condition is met or not according to the undisturbed frequency point, if so, interrupting the link or carrying out whole network unified frequency conversion, wherein the whole network unified frequency conversion means that a preset anti-interference remote control link sends a frequency conversion instruction to an Ad hoc network communication network of the whole air-ground combined interference system.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in the transmitter section, the peak value of the transmission signal in the time domain is reduced by a peak-to-average power ratio reduction strategy based on clipping and filtering, and the maximum amplitude of the transmission signal is limited to a preset specified amplitude.
Optionally, in another embodiment of the carrier processing method based on the air-ground combined interference system, the clipping and filtering based peak-to-average power ratio reduction strategy is to reduce the peak-to-average power ratio by clipping or nonlinear saturation near a peak of a transmission signal in a time domain, and specifically includes:
after the transmission data change from the frequency to the time domain, the transmission data are processed by a first-stage amplitude limiting module, a first phase compensation module and a BPF filtering module, and are continuously processed by a second-stage amplitude limiting module, a second phase compensation module and an LPF filtering module, so that the obtained time domain signal is output to a radio frequency end.
The second aspect of the present invention provides a carrier processing apparatus based on an air-ground joint interference system, where the apparatus includes:
the transmitting part module is used for correspondingly modulating the carrier waves of the transmission data by using BPSK, QPSK, 16QAM or 64QAM modulation modes according to the transmission data required by different sending rates and normalizing the mapping of all modulation;
and the receiving part module is used for receiving the complex signal containing the in-phase component and the orthogonal component, and judging the corresponding code element as recovered original transmission data when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
the pilot frequency module is used for inserting a pilot frequency signal into the frequency domain of the modulated carrier frequency spectrum to be used as a carrier synchronization signal and transforming transmission data from the frequency to a time domain signal through fast Fourier transform;
the compensation module is used for receiving the carrier synchronization signal subjected to the pilot frequency, transforming the time domain signal into a frequency domain signal through fast Fourier transform, extracting the pilot frequency according to the frequency domain signal, estimating the carrier frequency deviation through the pilot frequency, and compensating the received signal in the time domain according to the carrier frequency deviation.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the compensation module specifically includes:
and the carrier frequency deviation estimation unit is used for carrying out wide-range carrier frequency deviation estimation including integer carrier frequency deviation by using the acquisition mode and carrying out fine carrier frequency deviation estimation by using the tracking mode.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
a training symbol embedding module, configured to embed a specific training symbol in the transmission data in advance;
and the channel estimation and equalization module is used for performing channel estimation and equalization on each data symbol in the carrier by using the received training symbol for estimating the frequency response of the channel.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
the frequency point sensing module is used for periodically sensing frequency points in a certain frequency band range, knowing whether the current frequency spectrum is used by equipment or not, and recording the undisturbed frequency points;
and the detection and processing module is used for detecting whether a preset Ad hoc network link interruption condition is met or not according to the undisturbed frequency point, if so, interrupting the link or carrying out unified frequency conversion on the whole network, wherein the unified frequency conversion on the whole network refers to the fact that a preset anti-interference remote control link sends a frequency conversion instruction to the Ad hoc network communication network of the whole air-ground combined interference system.
Optionally, in another embodiment of the carrier processing apparatus based on air-ground joint interference system, the apparatus further includes:
and the peak-to-average power ratio reducing module is used for reducing the peak value of the transmission signal in the time domain in the fast Fourier transform through a peak-to-average power ratio reducing strategy based on amplitude limiting and filtering, and limiting the maximum amplitude of the transmission signal to a preset specified amplitude.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground combined interference system, the clipping and filtering based peak-to-average power ratio reduction strategy is to reduce the peak-to-average power ratio by clipping or nonlinear saturation near a peak of a transmission signal in a time domain, where the peak-to-average power ratio reduction module specifically includes:
and the peak-to-average ratio reduction processing unit is used for processing the data after changing from frequency to time domain, processing the data by the first-stage amplitude limiting module, the first phase compensation module and the BPF filtering module, and continuously processing the data by the second-stage amplitude limiting module, the second phase compensation module and the LPF filtering module so as to output the obtained time domain signal to a radio frequency end.
The third aspect of the present invention further provides a carrier processing device based on an air-ground combined interference system, where the carrier processing device based on the air-ground combined interference system includes a memory and at least one processor, where the memory has instructions stored therein, and the memory and the at least one processor are interconnected by a line; the at least one processor invokes the instructions in the memory to cause the air-ground based joint interference system carrier processing device to execute any one of the above-mentioned carrier processing methods of the air-ground based joint interference system.
The fourth aspect of the present invention further provides a computer-readable storage medium, on which a computer program is stored, wherein the computer program, when executed by a processor, implements the carrier processing method based on the air-ground joint interference system as described in any one of the above.
In the technical scheme provided by the invention, the carrier wave of the transmission data is correspondingly modulated by using BPSK, QPSK, 16QAM or 64QAM modulation modes according to the transmission data required by different sending rates at a transmitter part, and all modulated mappings are normalized; in the receiver part, receiving a complex signal containing in-phase and orthogonal components, and judging a corresponding code element as recovered original transmission data when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used during modulation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic process diagram of an embodiment of a carrier processing method based on an air-ground joint interference system in the embodiment of the present invention;
fig. 2 is a schematic diagram of an embodiment of a carrier processing apparatus based on an air-ground joint interference system in an embodiment of the present invention;
fig. 3 is a schematic diagram of an embodiment of a carrier processing device based on an air-ground joint interference system in an embodiment of the present invention.
Detailed Description
The embodiment of the invention provides a carrier processing method and related equipment based on an air-ground combined interference system, which are used for realizing carrier modulation and demodulation, carrier synchronization, carrier frequency deviation estimation, carrier channel equalization and peak-to-average ratio reduction processing, so that an ad hoc network has the characteristics of strong multipath fading resistance, strong interference resistance, high frequency utilization rate and suitability for high-speed data transmission.
In order to make the technical field of the invention better understand the scheme of the invention, the embodiment of the invention will be described in conjunction with the attached drawings in the embodiment of the invention.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Moreover, the terms "comprises," "comprising," or "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In order to prevent the complex electromagnetic environment application scene of the air-ground combined interference system from being considered, the electromagnetic environment, natural weather, communication distance and other factors are easily influenced, the caused multipath and time variation are two important influence factors, the multipath can cause the wireless signal to suffer frequency selective fading, and the time variation causes the corresponding time variation of the channel. Since the capability of the communication path in the ad hoc network system to transmit data changes with time, OFDM (Orthogonal Frequency Division Multiplexing) can be dynamically adapted to the ad hoc network, and can almost completely overcome the intersymbol interference caused by multipath, and is particularly suitable for the multi-user distributed ad hoc network of the air-ground combined interference system. The invention realizes the carrier modulation and demodulation, the carrier synchronization, the carrier frequency deviation estimation, the carrier channel equalization and the peak-to-average ratio reduction processing based on the OFDM, thereby leading the ad hoc network to have the characteristics of strong multipath fading resistance, strong anti-jamming capability, high frequency utilization rate and suitability for high-speed data transmission.
Referring to fig. 1, an embodiment of a carrier processing method based on an air-ground joint interference system in the embodiment of the present invention includes:
The transmitters of all networking resources in the space-ground combined interference system modulate information bit sequences into PSK/QAM symbols, then perform inverse fast Fourier transform on the corresponding symbols to convert the symbols into time domain signals, and finally transmit the time domain signals through corresponding wireless channels. In specific implementation, in the transmitter part, according to transmission data required by different transmission rates, the carrier of the transmission data is correspondingly modulated by using BPSK, QPSK, 16QAM or 64QAM modulation methods, and all modulated mappings are normalized, that is, according to different rate requirements, the OFDM subcarriers need to be modulated by using BPSK, QPSK, 16QAM or 64QAM modulation methods. After the data is encoded and interleaved, each 1, 2, 4 or 6 bits of the serial data stream are divided into a group, and the group is mapped into complex numbers according to a certain rule to form BPSK, QPSK, 16QAM or 64QAM modulation.
During transmission, the modulation scheme may change, such as BPSK modulation used for command frames in the transmission data, and another modulation used for data frames. In order to have the same average power for all the maps, the maps need to be normalized. Multiplying the mapped complex number by a normalization K mod And obtaining output data. Normalized quantity K mod The value of the Binary Phase Shift Keying (BPSK), QPSK, 16QAM or 64QAM modulation mode of the invention is different according to different modulation modes, and corresponds to the normalization quantity K mod Have values of 1,
1/42. For example, 16QAM modulation schemes have 16 samples on a constellation diagram, each sample representing a vector state, 16QAM has 16 states, each 4-bit binary specifies one of the 16 states, and 16QAM transmits a 4-bit map for each symbol time. Mapping the data by a preset 16QAM coding table to obtain I/Q data, and multiplying the I/Q data by the data
And normalizing to obtain the modulated I/Q value. And respectively carrying out analog-to-digital conversion on the I/Q data to obtain two paths of analog level signals which are used for multiplying cos omega t and sin omega t, thereby realizing modulation.
Accordingly, demodulation is required at the receiver portion in order to recover the transmitted data. The command frame in the transmission data adopts the most reliable BPSK modulation for ensuring the accuracy of information, and the data frame in the transmission data has four different modulation modes according to different rate requirements. For example, in 16QAM, since the 16QAM quadrature amplitude modulation changes both the amplitude and the phase of the carrier, it is a combination of ASK and PSK, and its mathematical form is: s (t) = Isin (w) c t)-Qcos(w c t); i, Q is the in-phase component and the quadrature component, respectively. In the baseband signal processing, the complex signal, which is typically composed of two components, in-phase and quadrature, is fed to the demodulation module. And the demodulation utilizes the received complex signal to recover the original digital information according to the modulation mapping relation used in the modulation, and in the demodulation process, when the complex signal falls in the corresponding rectangular area, the corresponding code element is judged to be the recovered original transmission data
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in the transmitter section, a pilot signal is inserted in the frequency domain of the modulated carrier spectrum as a carrier synchronization signal, and transmission data is converted from frequency to a time domain signal by fast fourier transform;
in the receiver part, a carrier synchronization signal which is subjected to pilot frequency is received, a time domain signal is transformed into a frequency domain signal through fast Fourier transform, the pilot frequency is extracted according to the frequency domain signal, carrier frequency deviation is estimated through the pilot frequency, and the received signal is compensated in the time domain according to the carrier frequency deviation.
In practical implementation, due to the characteristics of OFDM, the transmitter part transmits signals on multiple overlapping sub-channels, and in order to correctly receive the signals, orthogonality between sub-carriers must be strictly ensured, but because doppler shift and a transmitting/receiving crystal oscillator are not identical, a certain carrier frequency deviation often exists, which will destroy orthogonality between sub-carriers, and the influence of the frequency deviation on the phase is also additive. Therefore, in order to guarantee OFDM performance, carrier frequency synchronization must be performed. The baseband signal is up-converted to the passband due to the carrier modulation, and then down-converted to baseband at the receiver by using a local carrier with the same frequency. In general, there are two types of carrier frequency offset and carrier signal related distortion. One is phase noise caused by instability of the carrier signal generators of the transmitter and receiver, which can be modeled as a zero-mean wiener random process. Another frequency shift f by Doppler d And is caused by this. Let f c And f c ' denotes carrier frequencies of the transmitter and the receiver, respectively; f. of offset Representing the difference between the two, i.e. f offset ＝f c -f c '. Doppler shift f d By carrier frequency f c Co-determining with velocity v of the mobile terminal
Where c is the speed of light, and the normalized Carrier Frequency Offset (CFO) is defined as the ratio of the integer carrier frequency offset to the subcarrier spacing:
let epsilon i And ε f Representing the integer and fractional parts of epsilon, respectively, i.e. epsilon = epsilon i +ε f The difference in carrier frequency, for time domain signals x [ n ]]The carrier frequency deviation of epsilon will cause a deviation of 2 pi n epsilon and the phase will be proportional to epsilon and n, which is equivalent to the frequency signal X k]Which produces a frequency difference of-epsilon.
For the above carrier frequency deviation, the present invention is designed to insert pilot frequency in frequency domain, so that the receiver part can be recovered as carrier synchronization signal, and the sine wave corresponding to the line spectrum is called pilot signal and transmitted in each OFDM symbol, so that the carrier frequency deviation can be tracked.
First, two OFDM symbols y are synchronized l [n]And y l+D [n]Then, the time domain signal is transformed into a frequency domain signal by fast Fourier transform
And
for extracting the pilot. And finally, estimating the carrier frequency deviation by the frequency domain pilot frequency, and compensating the received signal in the time domain through the estimated carrier frequency deviation.
Optionally, in another embodiment of the carrier processing method based on the air-ground combined interference system, the estimating a carrier frequency offset through the pilot specifically includes:
a wide range of carrier frequency offset estimates, including integer carrier frequency offsets, is performed using the acquisition mode and a fine carrier frequency offset estimate is performed using the tracking mode.
In specific implementation, the invention adopts two different carrier frequency deviation estimation modes: an acquisition mode and a tracking mode. In acquisition mode, a wide range of carrier frequency deviations, including integer carrier frequency deviations, is estimated. In tracking mode, only a fine carrier frequency offset estimation is performed. Wherein the integer carrier frequency offset is estimated as:
Meanwhile, the fine carrier frequency offset is estimated as:
i.e. in acquisition mode, estimate epsilon acq And epsilon f Then compensating the carrier frequency offset by their sum, in tracking mode, only estimating epsilon f And then compensates the carrier frequency deviation by it.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
at a transmitter portion, embedding a specific training symbol in the transmission data in advance;
in the receiver portion, to estimate the frequency response of the channel, each data symbol in the carrier is channel estimated and equalized using the received training symbols.
The signal received by the receiver section is usually distorted due to the influence of the channel characteristics. In order to recover the bit information, the channel must be estimated and compensated at the receiver. Each carrier can be considered as an independent channel only if inter-carrier interference (ICI) does not occur, i.e., orthogonality between sub-carriers can be maintained. This orthogonality allows each subcarrier component of the received signal to be represented as the product of the transmitted signal and the channel frequency response of the subcarrier. Therefore, the transmission signal can be recovered only by estimating the channel response of each subcarrier.
The impulse response of a time-varying channel is typically represented as a discrete FIR filter:
According to different processing domains, the channel estimation is divided into a time domain and a frequency domain, wherein the time domain and the frequency domain are carried out before the discrete Fourier transform of a receiving end to estimate the impulse response of the channel; the latter, which is performed after the discrete fourier transform, estimates the channel frequency response. The two methods can be combined to carry out channel estimation in time domain and frequency domain jointly so as to fully mine the respective advantages of signal time domain processing and frequency domain processing.
The invention adopts a simple and efficient method to estimate the frequency response of the channel, namely, the channel estimation and equalization are carried out on each data symbol. Namely, in the transmitter part, embedding specific training symbols in the transmission data in advance; in the receiver portion, to estimate the frequency response of the channel, each data symbol in the carrier is channel estimated and equalized using the received training symbols. In the specific implementation, the OFDM symbol format received by the receiving end comprises a plurality of specific training symbols and a plurality of data symbols, and in the channel equalization process, the received training symbols are used for carrying out channel equalization on the channels of the data symbols.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in a receiver part, whether the current frequency spectrum is used by equipment is known by periodically sensing frequency points in a certain frequency band range, and the undisturbed frequency points are recorded;
and detecting whether a preset Ad hoc network link interruption condition is met or not according to the undisturbed frequency point, if so, interrupting the link or carrying out whole network unified frequency conversion, wherein the whole network unified frequency conversion means that a preset anti-interference remote control link sends a frequency conversion instruction to an Ad hoc network communication network of the whole air-ground combined interference system.
Because of the influence of interference of the surrounding environment of the air-ground combined interference system, in order to improve the anti-interference capability of the ad hoc network, the invention adopts a spectrum sensing technology, namely periodically sensing frequency points in a certain frequency band range and recording the frequency points which are not interfered. When the current self-networking link is interrupted and meets a certain condition, the link is considered to be interfered, the link can be automatically interrupted, or a frequency point selected from the non-interfered frequency points is recommended to an operator, the operator decides whether the whole network is uniformly switched, and when the operator confirms the whole network is uniformly switched, a frequency switching instruction is sent to the self-networking communication network of the whole air-ground combined interference system through a preset anti-interference remote control link. The receiver part of the invention receives baseband data after radio frequency down conversion, calculates the power of a link through AGC processing, and then obtains the power of the whole link by adding AGC to regulate the whole power, and the obtained power is compared with the power of the spectrum without use, so that whether the current spectrum is used by equipment or not can be obtained, namely, the spectrum sensing function is realized.
Optionally, in another embodiment of the carrier processing method based on the air-ground joint interference system, the method further includes:
in the transmitter section, the peak value of the transmission signal in the time domain is reduced by a peak-to-average power ratio reduction strategy based on clipping and filtering, and the maximum amplitude of the transmission signal is limited to a preset specified amplitude.
The clipping and filtering based peak-to-average power ratio reduction strategy is to reduce a peak-to-average power ratio by clipping or nonlinear saturation near a peak of a time-domain transmission signal, and specifically includes: after the transmission data change from the frequency to the time domain, the transmission data are processed by a first-stage amplitude limiting module, a first phase compensation module and a BPF filtering module, and are continuously processed by a second-stage amplitude limiting module, a second phase compensation module and an LPF filtering module, so that the obtained time domain signal is output to a radio frequency end.
In specific implementation, all subcarriers are added after the inverse fast fourier transform operation, so that the transmission signal in the time domain has a high peak value. Therefore, the multi-carrier system of OFDM has a high Peak-to-Average Power Ratio (PAPR) compared to the single carrier system. The high peak-to-average power ratio PAPR reduces the efficiency of the transmitter power amplifier and also reduces the signal to quantization noise ratio (SQNR) of the ADC and DAC devices, so the function of reducing the PAPR is considered in the design of the present invention.
PAPR reduction techniques can be divided into the following: clipping techniques, coding techniques, scrambling techniques, adaptive predistortion techniques, and discrete fourier transform spread spectrum techniques.
The clipping technique used in the present invention, which is clipping or non-linear saturation near the peak to reduce PAPR, is simple to implement, but it may cause in-band and out-of-band interference and also destroy the orthogonality between subcarriers.
However, in the implementation of the scheme, the clipping and filtering technique, i.e., filtering after clipping, can reduce the in-band and out-of-band interference to a great extent under the condition that the orthogonality is satisfied. The present invention is embodied by limiting the maximum amplitude of the transmitted signal to a pre-specified level, which implements a clipping and filtering based PAPR reduction scheme. Specifically, after the transmission data changes from the frequency to the time domain, the transmission data is processed by a first-stage amplitude limiting module, a first phase compensation module and a BPF (band pass filter) filtering module, and is continuously processed by a second-stage amplitude limiting module, a second phase compensation module and an LPF (low pass filter) filtering module, so that the obtained time domain signal is output to a radio frequency end. That is, after the data changes from frequency to time domain, the data is processed by the first stage of amplitude limiting, the output value caused by the operation destroys the orthogonality of the sub-carrier on a certain program, and simultaneously, the interference in band and out of band is caused, therefore, the phase compensation and BPF filtering module is added later, the problem brought by the clipping can be solved well by using the two modules.
In summary, in the embodiment of the present invention, the transmitter correspondingly modulates the carrier of the transmission data by using BPSK, QPSK, 16QAM, or 64QAM modulation methods according to the transmission data required by different transmission rates, and normalizes the mapping of all modulations; in the receiver part, receiving a complex signal containing in-phase and orthogonal components, and judging a corresponding code element to be restored original transmission data when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation.
Referring to fig. 2, the carrier processing method based on the air-ground combined interference system in the embodiment of the present invention is described above, and a carrier processing apparatus based on the air-ground combined interference system in the embodiment of the present invention is described below, where an embodiment of the carrier processing apparatus based on the air-ground combined interference system in the embodiment of the present invention includes:
a transmitting part module 11, configured to modulate a carrier of the transmission data correspondingly in a BPSK, QPSK, 16QAM, or 64QAM modulation manner according to transmission data required by different sending rates, and normalize mapping of all modulations;
a receiving part module 12, configured to receive a complex signal containing in-phase and quadrature components, and determine, according to a modulation mapping relation used during modulation, that a corresponding symbol is recovered as original transmission data when the complex signal falls in a corresponding rectangular region.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
the pilot frequency module is used for inserting a pilot frequency signal into the frequency domain of the modulated carrier frequency spectrum to be used as a carrier synchronization signal and transforming transmission data from the frequency to a time domain signal through fast Fourier transform;
the compensation module is used for receiving the carrier synchronization signal subjected to the pilot frequency, transforming the time domain signal into a frequency domain signal through fast Fourier transform, extracting the pilot frequency according to the frequency domain signal, estimating the carrier frequency deviation through the pilot frequency, and compensating the received signal in the time domain according to the carrier frequency deviation.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the compensation module specifically includes:
and the carrier frequency deviation estimation unit is used for carrying out wide-range carrier frequency deviation estimation including integer carrier frequency deviation by using the acquisition mode and carrying out fine carrier frequency deviation estimation by using the tracking mode.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
a training symbol embedding module, configured to embed a specific training symbol in the transmission data in advance;
and the channel estimation and equalization module is used for performing channel estimation and equalization on each data symbol in the carrier by using the received training symbol for estimating the frequency response of the channel.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
the frequency point sensing module is used for periodically sensing frequency points in a certain frequency band range, knowing whether the current frequency spectrum is used by equipment or not, and recording the frequency points which are not interfered;
and the detection and processing module is used for detecting whether a preset Ad hoc network link interruption condition is met or not according to the undisturbed frequency point, if so, interrupting the link or carrying out unified frequency conversion on the whole network, wherein the unified frequency conversion on the whole network refers to the fact that a preset anti-interference remote control link sends a frequency conversion instruction to the Ad hoc network communication network of the whole air-ground combined interference system.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground joint interference system, the apparatus further includes:
and the peak-to-average power ratio reducing module is used for reducing the peak value of the transmission signal in the time domain in the fast Fourier transform through a peak-to-average power ratio reducing strategy based on amplitude limiting and filtering, and limiting the maximum amplitude of the transmission signal to a preset specified amplitude.
Optionally, in another embodiment of the carrier processing apparatus based on the air-ground combined interference system, the clipping and filtering based peak-to-average power ratio reduction strategy is to reduce the peak-to-average power ratio by clipping or nonlinear saturation near a peak of a transmission signal in a time domain, where the peak-to-average power ratio reduction module specifically includes:
and the peak-to-average ratio reduction processing unit is used for processing the data after changing from frequency to time domain, processing the data by the first-stage amplitude limiting module, the first phase compensation module and the BPF filtering module, and continuously processing the data by the second-stage amplitude limiting module, the second phase compensation module and the LPF filtering module so as to output the obtained time domain signal to a radio frequency end.
It should be noted that the apparatus in the embodiment of the present invention may be configured to implement all technical solutions in the foregoing method embodiments, and the functions of each functional module may be implemented specifically according to the method in the foregoing method embodiments, and the specific implementation process may refer to the relevant description in the foregoing example, which is not described herein again. Fig. 2 describes in detail the carrier processing apparatus based on the air-ground joint interference system in the embodiment of the present invention from the perspective of a modular functional entity, and the carrier processing apparatus based on the air-ground joint interference system in the embodiment of the present invention from the perspective of hardware processing.
Fig. 3 is a schematic structural diagram of a carrier processing apparatus based on an air-ground joint interference system according to an embodiment of the present invention, where the carrier processing apparatus 300 based on an air-ground joint interference system may generate a relatively large difference due to different configurations or performances, and may include one or more processors (CPUs) 301 (e.g., one or more processors) and a memory 309, and one or more storage media 308 (e.g., one or more mass storage devices) storing an application 307 or data 306. Memory 309 and storage media 308 may be, among other things, transient storage or persistent storage. The program stored on the storage medium 308 may include one or more modules (not shown), each of which may include a series of instruction operations in a boolean variable store computed on a graph. Still further, the processor 301 may be configured to communicate with the storage medium 308 to execute a series of instruction operations in the storage medium 308 on the carrier processing device 300 based on the air-ground combined interference system.
The air-ground based joint interference system carrier processing apparatus 300 may further include one or more power supplies 302, one or more wired or wireless network interfaces 303, one or more input-output interfaces 304, and/or one or more operating systems 305, such as Windows server, mac OS X, unix, linux, freeBSD, and so on. Those skilled in the art will appreciate that the structure of the carrier processing device based on the air-ground joint interference system shown in fig. 3 does not constitute a limitation to the carrier processing device based on the air-ground joint interference system, and may include more or less components than those shown, or combine some components, or arrange different components.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium, which may be non-volatile or volatile. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a portable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, an optical disk, or other various media capable of storing program codes.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A carrier processing method based on an air-ground combined interference system is characterized by comprising the following steps:
in the transmitter part, according to the transmission data required by different sending rates, the carrier wave of the transmission data is correspondingly modulated by using BPSK, QPSK, 16QAM or 64QAM modulation modes, and all the modulated mappings are normalized;
in the receiver part, a complex signal containing in-phase and orthogonal components is received, and when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation, a corresponding code element is judged to be recovered original transmission data.
2. The method for processing carriers based on the air-ground joint interference system according to claim 1, further comprising:
in the transmitter section, a pilot signal is inserted in the frequency domain of the modulated carrier spectrum as a carrier synchronization signal, and transmission data is converted from frequency to a time domain signal by fast fourier transform;
in the receiver part, a carrier synchronization signal which is subjected to pilot frequency is received, a time domain signal is transformed into a frequency domain signal through fast Fourier transform, the pilot frequency is extracted according to the frequency domain signal, carrier frequency deviation is estimated through the pilot frequency, and the received signal is compensated in the time domain according to the carrier frequency deviation.
3. The method for processing carriers based on the air-ground combined interference system according to claim 2, wherein the estimating a carrier frequency offset through the pilot frequency specifically includes:
a wide range of carrier frequency offset estimates, including integer carrier frequency offsets, is performed using the acquisition mode and a fine carrier frequency offset estimate is performed using the tracking mode.
4. The method for processing carriers based on the air-ground combined interference system according to claim 1, further comprising:
at a transmitter portion, embedding a specific training symbol in the transmission data in advance;
in the receiver portion, to estimate the frequency response of the channel, each data symbol in the carrier is channel estimated and equalized using the received training symbols.
5. The method for processing carriers based on the air-ground joint interference system according to claim 1, further comprising:
in a receiver part, whether the current frequency spectrum is used by equipment is known by periodically sensing frequency points in a certain frequency band range, and the undisturbed frequency points are recorded;
and detecting whether a preset Ad hoc network link interruption condition is met or not according to the undisturbed frequency point, if so, interrupting the link or carrying out whole network unified frequency conversion, wherein the whole network unified frequency conversion means that a preset anti-interference remote control link sends a frequency conversion instruction to an Ad hoc network communication network of the whole air-ground combined interference system.
6. The method for processing carriers based on the air-ground joint interference system according to claim 2, further comprising:
in the transmitter section, the peak value of the transmission signal in the time domain is reduced by a peak-to-average power ratio reduction strategy based on clipping and filtering, and the maximum amplitude of the transmission signal is limited to a preset specified amplitude.
7. The method according to claim 6, wherein the clipping and filtering based peak-to-average power ratio reduction strategy is to reduce the peak-to-average power ratio by clipping or nonlinear saturation near the peak of the time-domain transmission signal, and specifically comprises:
after the transmission data change from the frequency to the time domain, the transmission data are processed by a first-stage amplitude limiting module, a first phase compensation module and a BPF filtering module, and are continuously processed by a second-stage amplitude limiting module, a second phase compensation module and an LPF filtering module, so that the obtained time domain signal is output to a radio frequency end.
8. An apparatus for processing carrier based on air-ground joint interference system, the apparatus comprising:
a transmitting part module, configured to modulate a carrier of the transmission data correspondingly in a BPSK, QPSK, 16QAM, or 64QAM modulation manner according to transmission data required by different sending rates, and normalize mapping of all modulations;
and the receiving part module is used for receiving the complex signal containing the in-phase component and the orthogonal component, and judging the corresponding code element as recovered original transmission data when the complex signal falls in a corresponding rectangular area according to a modulation mapping relation used in modulation.
9. The carrier processing device based on the air-ground joint interference system is characterized by comprising a memory and at least one processor, wherein the memory stores instructions, and the memory and the at least one processor are interconnected through a line; the at least one processor invokes the instructions in the memory to cause the carrier processing device of the air-ground based joint interference system to execute the carrier processing method of the air-ground based joint interference system according to any one of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, wherein the computer program, when being executed by a processor, implements the carrier processing method of the air-ground based joint interference system according to any one of claims 1 to 7.
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