CN113098558B - Multi-sequence complex spread spectrum transmission method and system based on sequence complex correlation processing - Google Patents
Multi-sequence complex spread spectrum transmission method and system based on sequence complex correlation processing Download PDFInfo
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- CN113098558B CN113098558B CN202110344690.2A CN202110344690A CN113098558B CN 113098558 B CN113098558 B CN 113098558B CN 202110344690 A CN202110344690 A CN 202110344690A CN 113098558 B CN113098558 B CN 113098558B
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B1/707—Spread spectrum techniques using direct sequence modulation
- H04B1/7097—Interference-related aspects
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
A multi-sequence complex spread spectrum transmission method and system based on sequence complex correlation processing belongs to the technical field of wireless communication. The invention solves the problems of poor Doppler frequency shift resistance, complex equipment and high implementation cost of the traditional direct spread spectrum technology. The invention relates to a modulation and demodulation method for multi-sequence spread spectrum by mapping different multi-system data bits by using complex sequences. Since the complex sequence is not sensitive to phase offset and Doppler shift, the Doppler shift resistance of the system is effectively enhanced. And a traditional direct-spread carrier synchronization module is omitted at a receiving end, a traditional spread spectrum phase-locked loop is not needed, and the complexity and the implementation cost of direct-spread system equipment are reduced. The invention can be applied to the technical field of wireless communication.
Description
Technical Field
The invention belongs to the technical field of wireless communication, and particularly relates to a multi-sequence complex spread spectrum transmission method and system based on sequence complex correlation processing.
Background
The physical layer modulation method of information has been a key issue in the field of wireless communication, and the Direct Sequence Spread Spectrum (DSSS) is a modulation method widely used at present. A block diagram of a common direct spread spectrum system is shown in fig. 1. The traditional direct spread spectrum technology mainly utilizes a real pseudo-random code to perform spectrum spreading and remodulation transmission on information, and utilizes the characteristics of large frequency bandwidth and good self-cross-correlation performance of the pseudo-random code to enable a transmitted signal to have a series of advantages of multipath resistance, narrow-band interference resistance, low spectrum density, good confidentiality and the like. However, the direct spread spectrum technology has the disadvantages of complex equipment, high implementation cost, poor resistance to doppler shift, and the like, which undoubtedly restricts the application scenario of the direct spread spectrum technology.
Disclosure of Invention
The invention aims to solve the problems of poor Doppler frequency shift resistance, complex equipment and high implementation cost of the traditional direct spread spectrum technology, and provides a multi-sequence complex spread spectrum transmission method and a multi-sequence complex spread spectrum transmission system based on sequence complex correlation processing.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing specifically comprises the following steps:
a transmitter section:
step one, the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
represents the transmitted M-th bit binary data, wherein M is 1,2, …, M is a positive integer,
to the sequence
After serial-to-parallel conversion, converting the serial-to-parallel converted result into decimal symbol value
Step two, reading N complex sequences C 0 ,C 1 ,…,C N-1 ，N＝2 M Then will be
Mapped to complex sequence of corresponding sequence numbers
Will be provided with
The real part of (a) passes through the I path,
multiplying the real part of the carrier wave by the local carrier wave to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
converting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna;
a receiver section:
thirdly, receiving signals in a channel through a receiver antenna, and obtaining analog signals after the received signals pass through a radio frequency filter;
step four, after down-conversion, the analog signal is converted into a digital intermediate frequency signal through an A/D converter; dividing the digital intermediate frequency signal into I, Q paths, wherein, I path digital intermediate frequency signal is multiplied with local carrier, Q path digital intermediate frequency signal is multiplied with local carrier shifted 90 degree, the multiplication result of I path and the multiplication result of Q path are passed through low pass filter respectively, finally, a real number sequence with length Z is obtained in I path and Q path respectively;
taking the real number sequence obtained by the path I as a real part and the real number sequence obtained by the path Q as an imaginary part to obtain a complex sequence
Step five, mixing
With each complex sequence C of the transmitter part 0 ,C 1 ,…,C N-1 Respectively correlated to obtain
The correlation result with each complex sequence is then modulo-valued, and the resulting modulo values are represented as
Step six, mixing
Inputting the comparison decision device to compare the magnitude, selecting the maximum module value, and mapping the complex sequence of the transmitter part corresponding to the maximum module value back to the decimal symbol value
And decimal symbol value
Converting into binary representation, and performing parallel-to-serial conversion on binary representation result to recover communicationM-bit binary data transmitted by the system.
A multi-sequence complex spread spectrum transmission system based on sequence complex correlation processing is used for executing a multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing.
A multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing comprises the following working processes in a transmitter part:
step 1, the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
represents the transmitted M-th bit binary data, wherein M is 1,2, …, M is a positive integer,
to the sequence
After serial-to-parallel conversion, converting the serial-to-parallel converted result into decimal symbol value
Will be provided with
Real part ofThe mixture passes through the path I and then passes through the path I,
multiplying the real part of the carrier wave by the local carrier wave to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
and converting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna.
The invention has the beneficial effects that: the invention relates to a modulation and demodulation method for multi-sequence spread spectrum by mapping different multi-system data bits by using complex sequences. Since the complex sequence is not sensitive to phase offset and Doppler shift, the Doppler shift resistance of the system is effectively enhanced. And a traditional direct-spread carrier synchronization module is omitted at a receiving end, a traditional spread spectrum phase-locked loop is not needed, and the complexity and the implementation cost of direct-spread system equipment are reduced.
The invention further enhances the confidentiality and the safety of information transmission on the basis of keeping the advantages of detection resistance, interception resistance and multipath resistance of the traditional spread spectrum, and the high-order number of the complex sequence multi-sequence spread spectrum can improve the speed of information transmission. When transmitting quaternary and above data, the bit error rate performance of complex sequence multi-sequence spread spectrum is obviously superior to that of traditional multi-system modulation modes such as MPSK and MQAM.
Drawings
FIG. 1 is a block diagram of a conventional direct spread spectrum system;
FIG. 2 is an overall system block diagram of the present invention;
FIG. 3 is a plot of the bit error rate for a double ZC sequence under the effect of different signal-to-noise ratios and different cross-correlation values;
in the figure, BER is bit error rate, Eb/N0 is signal-to-noise ratio;
FIG. 4 is a diagram comparing the Doppler shift resistance of a double ZC sequence and a direct spread spectrum sequence;
FIG. 5 is a graph comparing the fixed frequency offset resistance of a double ZC sequence with a direct spreading sequence;
FIG. 6 is a graph comparing error rate performance in 8ZC sequence, 8PSK and 8QAM Gaussian channels;
FIG. 7 is a graph comparing error rate performance in 16ZC sequence, 16PSK and 16QAM Gaussian channels.
Detailed Description
First, a binary data source is taken as an example, and the embodiment is described with reference to fig. 2. The method for transmitting multiple-sequence complex spread spectrum based on sequence complex correlation processing in this embodiment specifically includes the following steps:
a transmitter section:
step one, suppose that the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
represents the transmitted M-th bit binary data, wherein M is 1,2, …, M is a positive integer,
to the sequence
After the serial-parallel conversion is carried out, the result after the serial-parallel conversion is carried outConversion to decimal symbol values
Data in the binary data sequence to be transmitted may also be grouped, for example, if the length of the binary data sequence to be transmitted is n · M, serial-to-parallel conversion may be performed once for every M bits of binary data, that is, a process of step one is performed once for every M bits of binary data;
step two, reading N complex sequences C stored in the system in advance 0 ,C 1 ,…,C N-1 ，N＝2 M Then will be
Mapped to complex sequence of corresponding sequence numbers
Will be provided with
The real part of (a) passes through the I path,
multiplying the real part of the carrier wave by the local carrier wave to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
converting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna to finish t 1 ～t 2 Sending M-bit information data at a moment;
comparing with the conventional direct-spread-spectrum transmitter part in fig. 1, it can be seen that compared to I, Q paths which transmit the product of information code and real-spread-spectrum code when using a single real sequence in the conventional direct-spread-spectrum, the complex-sequence multi-sequence spread-spectrum uses multiple orthogonal complex sequences, I, Q paths transmit only the real part and imaginary part of the complex sequence, and have a larger difference;
a receiver section:
thirdly, receiving signals in a channel through a receiver antenna, and obtaining analog signals after the received signals pass through a radio frequency filter;
step four, after down-conversion is carried out on the analog signal, a digital intermediate frequency signal is obtained through an A/D converter; dividing the digital intermediate frequency signal into I, Q paths, wherein, I path digital intermediate frequency signal is multiplied with local carrier, Q path digital intermediate frequency signal is multiplied with local carrier shifted 90 degree, the multiplication result of I path and the multiplication result of Q path are passed through low pass filter respectively, finally, a real number sequence with length Z is obtained in I path and Q path respectively;
taking the real number sequence obtained by the path I as a real part and the real number sequence obtained by the path Q as an imaginary part to obtain a complex sequence
Step five, mixing
With each complex sequence C of the transmitter part 0 ,C 1 ,…,C N-1 Respectively correlated to obtain
The correlation result with each complex sequence is then modulo-valued, and the resulting modulo values are represented as
Step six, mixing
The input of the comparison decision device is compared in size, the maximum modulus value is selected from the input comparison decision device, and the complex sequence (C) of the transmitter part corresponding to the maximum modulus value is selected 0 ,C 1 ,…,C N-1 One of) is mapped back to a decimal symbol value
And decimal symbol value
And converting the binary representation into binary representation, and recovering the M-bit binary data transmitted by the communication system after performing parallel-serial conversion on the binary representation result.
The I, Q two-path demodulation can be directly carried out at the receiving end without passing through a carrier synchronization module, the demodulation mainly comprises the steps that I path digital intermediate frequency signals are multiplied by local carriers, Q path digital intermediate frequency signals are multiplied by local carriers shifted by 90 degrees, and the multiplication results of the I path and the Q path pass through low-pass filters respectively.
Comparing with the traditional direct spread spectrum receiver part of fig. 1, we can see that the traditional direct spread spectrum requires carrier synchronization, but in the present invention, since the complex sequence is not sensitive to frequency offset, the complex sequence multi-sequence spread spectrum does not need to perform carrier synchronization, and directly performs I, Q two-way demodulation (the main method of demodulation is that I-way digital intermediate frequency signal is multiplied by local carrier, Q-way digital intermediate frequency signal is multiplied by local carrier shifted by 90 °, and the multiplication result of I-way and the multiplication result of Q-way are passed through low pass filters respectively). During demodulation, the two paths are I, Q for demodulation respectively, although the forms are similar, the real part and the imaginary part are obtained respectively through I, Q paths for judgment in the traditional direct sequence spread spectrum, and complex sequence multi-sequence spread spectrum is the operation of a complex domain; the traditional direct spread is to judge the amplitude or phase according to the information baseband modulation mode, and the complex sequence multi-sequence spread spectrum is to compare the magnitude of the modulus.
The second embodiment is as follows: this embodiment differs from the first embodiment in that the decimal notation values
Expressed as:
the third concrete implementation mode: the difference between this embodiment and the second embodiment is that the N complex sequences C 0 ,C 1 ,…,C N-1 The expression of (a) is:
…
where e is the base of the natural logarithm, j is the unit of an imaginary number, Z represents the length of each complex sequence, p k,l For the phase of the k-th complex sequence at point l, A k,l The amplitude of the k-th complex sequence at point l is 1,2, …, Z, k is 0,1, …, N-1.
The fourth concrete implementation mode: the third difference between this embodiment and the third embodiment is that, in the N complex sequences, any two complex sequences are approximately orthogonal and the energy of each complex sequence is guaranteed to be the same.
The complex sequence is a discrete sequence composed of a plurality of complex numbers and distinguished from the real sequence, and the complex sequence with the length of N can be expressed as
In the form of (1), wherein A 1 ,A 2 ,…,A N Amplitude of each point of the sequence, p 1 ,p 2 ,…,p N The values are real numbers for the phases of all points of the sequence; or is represented by [ a ] 1 +jb 1 ,a 2 +jb 2 ,…,a N +jb N ]Form (a) of 1 ,a 2 ,…,a N Representing the real part of each point of the sequence, b 1 ,b 2 ,…,b N And the imaginary parts of all points of the sequence are represented, and the values are real numbers. The physical meaning of its communication domain can be expressed as a real sequence [ a ] 1 ,a 2 ,…,a N ]And a real sequence [ b ] orthogonal thereto 1 ,b 2 ,…,b N ]And (3) superposition. The correlation operation of complex sequences is different from real correlation, sequences
And
make correlation, its formula is expressed as
When R ≈ 0 we call sequence C 1 And sequence C 2 Approximately orthogonal. A sequence of repetitionThe energy carried by a column is usually measured by the sequence autocorrelation value, e.g. by
Represents sequence C 1 Energy of
Is expressed as
The screened complex sequences have the autocorrelation modulus as large as possible when aligned, the modulus of the mutual values is as small as possible when aligned, and the complex sequences are insensitive to phase shift and frequency shift change generated in the channel transmission process, so the invention provides a complex sequence-based multi-sequence spread spectrum method, which not only inherits a series of advantages of traditional spread spectrum such as anti-interference, anti-capture and the like, but also has other advantages such as anti-frequency shift and anti-phase offset.
The fifth concrete implementation mode: the difference between the present embodiment and the fourth embodiment is that, in the fifth step, the step
With each complex sequence C of the transmitter part 0 ,C 1 ,…,C N-1 Respectively correlated to obtain
And obtaining a module value of the correlation result of each complex sequence, wherein the specific process comprises the following steps:
wherein the content of the first and second substances,
is composed of
And the kthModulus of the correlation result of the complex sequence.
The sixth specific implementation mode: the present embodiment provides a multi-sequence spread spectrum transmission system based on a sequence complex correlation process, which is used to implement a multi-sequence spread spectrum transmission method based on a sequence complex correlation process in any one of the first to fifth embodiments.
The seventh embodiment: in this embodiment, a multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing includes, in a transmitter part:
a transmitter section:
step 1, suppose that the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
represents the transmitted M-th bit binary data, wherein M is 1,2, …, M is a positive integer,
to the sequence
After serial-to-parallel conversion, converting the serial-to-parallel converted result into decimal symbol value
Data in the binary data sequence to be transmitted may also be grouped, for example, if the length of the binary data sequence to be transmitted is n · M, serial-to-parallel conversion may be performed once for every M bits of binary data, that is, a process of step one is performed once for every M bits of binary data;
Will be provided with
The real part of (a) passes through the I path,
multiplying the real part of the carrier wave by the local carrier wave to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
addition resultConverting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna to finish t 1 ～t 2 And transmitting the M-bit information data of the time.
The specific implementation mode is eight: seventh difference from the first embodiment is that the decimal symbol value
Expressed as:
the specific implementation method nine: this embodiment differs from the eighth embodiment in that the N complex sequences C 0 ,C 1 ,…,C N-1 The expression of (a) is:
…
where e is the base of the natural logarithm, j is the unit of an imaginary number, Z represents the length of each complex sequence, p k,l For the phase of the k-th complex sequence at point l, A k,l The amplitude of the k-th complex sequence at point l is 1,2, …, Z, k is 0,1, …, N-1.
The detailed implementation mode is ten: the difference between this embodiment and the ninth embodiment is that, in the N complex sequences, any two complex sequences are approximately orthogonal and the energy of each complex sequence is guaranteed to be the same.
Simulation result
A Zadoff-Chu sequence (ZC sequence for short) is one of the common complex sequences, which has good correlation properties. Without loss of generality, a Zadoff-Chu sequence is selected as a representative of a complex sequence in simulation, and the performance of the complex sequence is verified in a simulation mode.
1. The correlation properties of the complex sequence affect the bit error rate performance.
Three pairs of ZC sequences with the same length are selected for double ZC sequence spread spectrum in simulation, and due to the characteristics of the ZC sequences, normalized autocorrelation values when the ZC sequences are aligned are all 1. Under the Gaussian channel, the bit error rate performance of the double ZC sequences under the action of different signal-to-noise ratios and different cross-correlation values is compared, and the simulation result is shown in FIG. 3. From simulation results, it can be seen that the more the complex sequence multi-sequence spread spectrum cross-correlation value is close to 0, the more excellent the error rate performance is.
2. Resisting Doppler frequency shift
The simulation selects a double ZC sequence spread spectrum sequence and an m direct spread spectrum sequence, and under the action of different signal-to-noise ratios and different maximum Doppler frequency shifts, the error rate performances of the double ZC sequence spread spectrum sequence and the m direct spread spectrum sequence are compared under a flat Rayleigh fading channel, and the simulation result is shown in figure 4. The simulation result shows that the complex sequence multi-sequence spread spectrum has obvious Doppler frequency shift resistance.
3. Resistant to fixed frequency shifts
The simulation selects the double ZC sequence spread spectrum and the m direct spread spectrum sequence, and under the Gaussian noise channel, the bit error rate performance of the double ZC sequence spread spectrum and the m direct spread spectrum sequence under the action of different signal-to-noise ratios and different fixed frequency shifts is compared, and the simulation result is shown in FIG. 5. It can be seen from the simulation results that the complex sequence multi-sequence spread spectrum also has a certain resistance effect on fixed frequency offset.
4. Error rate performance in multilevel
Under a gaussian channel, comparing the error rate performances of multi-ZC sequence spreading, MPSK, and MQAM of the same modulation order under different signal-to-noise ratios, as shown in fig. 6, the error rate performance is compared when M is 8, and when the signal-to-noise ratio is greater than about 3dB, the error rate performance advantage of 8ZC sequence spreading is obvious. Fig. 7 is a comparison of the error rate performance when M is 16, and it can be seen from the simulation result that the error rate performance of the spreading of the 16ZC sequence is significantly better than that of 16PSK and 16QAM after the snr is greater than 0 dB.
The above-described calculation examples of the present invention are merely to explain the calculation model and the calculation flow of the present invention in detail, and are not intended to limit the embodiments of the present invention. It will be apparent to those skilled in the art that other variations and modifications of the present invention can be made based on the above description, and it is not intended to be exhaustive or to limit the invention to the precise form disclosed, and all such modifications and variations are possible and contemplated as falling within the scope of the invention.
Claims (7)
1. A multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing is characterized by comprising the following steps:
a transmitter section:
step one, the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
represents the transmitted M-th bit binary data, wherein M is 1,2, …, M is a positive integer,
to the sequence
After serial-to-parallel conversion, converting the serial-to-parallel converted result into decimal symbol value
Step two, reading N complex sequences C 0 ,C 1 ,…,C N-1 ，N＝2 M Then will be
Mapped to complex sequence of corresponding sequence numbers
The N complex sequences C 0 ,C 1 ,…,C N-1 The expression of (a) is:
…
where e is the base of the natural logarithm, j is the unit of an imaginary number, Z represents the length of each complex sequence, p k,l For the phase of the k-th complex sequence at point l, A k,l The amplitude of the kth complex sequence at point l, l is 1,2, …, Z, k is 0,1, …, N-1;
will be provided with
The real part of (a) passes through the I path,
multiplying the real part of the local carrier by the local carrier to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
converting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna;
a receiver section:
thirdly, receiving signals in a channel through a receiver antenna, and obtaining analog signals after the received signals pass through a radio frequency filter;
step four, after down-conversion is carried out on the analog signal, a digital intermediate frequency signal is obtained through an A/D converter; dividing the digital intermediate frequency signal into I, Q paths, wherein, I path digital intermediate frequency signal is multiplied with local carrier, Q path digital intermediate frequency signal is multiplied with local carrier shifted 90 degree, the multiplication result of I path and the multiplication result of Q path are passed through low pass filter respectively, finally, a real number sequence with length Z is obtained in I path and Q path respectively;
taking the real number sequence obtained by the path I as a real part and the real number sequence obtained by the path Q as an imaginary part to obtain a complex sequence
Step five, mixing
With each complex sequence C of the transmitter part 0 ,C 1 ,…,C N-1 Respectively correlated to obtain
The correlation result with each complex sequence is then modulo-valued, and the resulting modulo values are represented as
The device is to
With each complex sequence C of the transmitter part 0 ,C 1 ,…,C N-1 Respectively correlated to obtain
And obtaining a module value of the correlation result of each complex sequence, wherein the specific process comprises the following steps:
wherein the content of the first and second substances,
is composed of
A modulus of the correlation result with the kth complex sequence;
step six, mixing
Inputting the comparison decision device to compare the magnitude, selecting the maximum module value, and mapping the complex sequence of the transmitter part corresponding to the maximum module value back to the decimal symbol value
And decimal symbol value
And converting the binary representation into binary representation, and recovering the M-bit binary data transmitted by the communication system after performing parallel-serial conversion on the binary representation result.
2. The method as claimed in claim 1, wherein the decimal symbol value is a symbol value of a symbol with a multiple sequence spread spectrum
Expressed as:
3. the method according to claim 2, wherein any two complex sequences in the N complex sequences are approximately orthogonal and energy of each complex sequence is the same.
4. A multi-sequence spread-spectrum transmission system based on the complex sequence correlation process, characterized in that the system is used for executing the multi-sequence spread-spectrum transmission method based on the complex sequence correlation process as claimed in any one of claims 1 to 3.
5. A multi-sequence complex spread spectrum transmission method based on sequence complex correlation processing is characterized in that the method works in a transmitter part as follows:
a transmitter section:
step 1, the communication system is at t 1 ～t 2 The M-bit binary data are transmitted at the same time, and the sequence formed by the transmitted M-bit binary data is expressed as
Wherein the content of the first and second substances,
representsThe transmitted M-th bit binary data, M is 1,2, …, M, M is positive integer,
to the sequence
After serial-to-parallel conversion, converting the serial-to-parallel converted result into decimal symbol value
Step 2, reading N complex sequences C 0 ,C 1 ,…,C N-1 ，N＝2 M Then will be
Mapped to complex sequence of corresponding sequence numbers
The N complex sequences C 0 ,C 1 ,…,C N-1 The expression of (a) is:
…
where e is the base of the natural logarithm, j is the unit of an imaginary number, Z represents the length of each complex sequence, p k,l For the phase of the k-th complex sequence at point l, A k,l For the amplitude of the k-th complex sequence at point lThe values l 1,2, …, Z, k 0,1, …, N-1;
will be provided with
The real part of (a) passes through the I path,
multiplying the real part of the carrier wave by the local carrier wave to obtain a multiplication result of the path I;
will be provided with
The imaginary part of (a) is passed through a Q-path,
the imaginary part of the Q path is multiplied by the local carrier wave which is subjected to 90-degree phase shift to obtain a multiplication result of the Q path;
correspondingly adding the multiplication result of the path I and the multiplication result of the path Q, and finishing intermediate frequency digital carrier modulation after adding;
and converting the digital intermediate frequency signal into an analog intermediate frequency signal through a D/A converter, converting the analog intermediate frequency signal into a radio frequency signal through up-conversion, amplifying the transmitting power of the radio frequency signal through a power amplifier, and transmitting the radio frequency signal to a channel through an antenna.
6. The method as claimed in claim 5, wherein the decimal symbol value is a symbol value of a symbol with a multiple sequence spread spectrum
Expressed as:
7. the method according to claim 6, wherein any two of the N complex sequences are approximately orthogonal and energy of each complex sequence is the same.
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