CN111988253B - Multi-carrier multi-element differential chaotic shift keying noise suppression system and method - Google Patents

Multi-carrier multi-element differential chaotic shift keying noise suppression system and method Download PDF

Info

Publication number
CN111988253B
CN111988253B CN202010897102.3A CN202010897102A CN111988253B CN 111988253 B CN111988253 B CN 111988253B CN 202010897102 A CN202010897102 A CN 202010897102A CN 111988253 B CN111988253 B CN 111988253B
Authority
CN
China
Prior art keywords
signal
matrix
information
noise
reference signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN202010897102.3A
Other languages
Chinese (zh)
Other versions
CN111988253A (en
Inventor
徐位凯
任华荣
蔡相明
王琳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xiamen University
Original Assignee
Xiamen University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xiamen University filed Critical Xiamen University
Priority to CN202010897102.3A priority Critical patent/CN111988253B/en
Publication of CN111988253A publication Critical patent/CN111988253A/en
Application granted granted Critical
Publication of CN111988253B publication Critical patent/CN111988253B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/001—Modulated-carrier systems using chaotic signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2626—Arrangements specific to the transmitter only
    • H04L27/2627—Modulators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2649—Demodulators

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

A multi-carrier multi-element differential chaotic shift keying noise suppression system and a method belong to the field of noise suppression in wireless communication technology. The system transmitting end comprises a chaotic signal generator, a serial/parallel converter, a bit/symbol converter, a multi-element DCSK modulator, a pulse shaping filter, a multiplier and an adder; the receiving end comprises a matched filter, a sampling module, an averaging module, a noise suppression module and a multi-element DCSK modulator. And at a receiving end, using the correlation coefficient of the received reference signal and the information-bearing signal as a weight factor, using the weight factor as feedback to update the previous reference signal and the previous information-bearing signal and inhibit noise in a transmission signal, and verifying the effectiveness of the proposed method by using computer simulation. Under the additive white Gaussian noise channel and the multipath fading channel, the noise in the transmission signal is obviously reduced, and the system error rate performance is improved. Has wide application prospect in the future wireless communication application.

Description

Multi-carrier multi-element differential chaotic shift keying noise suppression system and method
Technical Field
The invention belongs to the field of noise suppression in wireless communication technology, and particularly relates to a multi-carrier multi-element differential chaotic shift keying noise suppression system and method.
Background
The inherent broadband, non-periodic and noise-like characteristics of the chaotic signals enable the chaotic signals to have wide application prospects in spread spectrum communication and secret communication. Therefore, chaotic communication using chaotic signals as carriers has been widely studied in the field of wireless communication, and many chaotic communication systems have been proposed by domestic and foreign scholars, wherein one important modulation scheme is Differential Chaos Shift Keying (DCSK). The DCSK system can realize a simple receiver that does not require Channel State Information (CSI), and thus the system does not require Channel estimation and chaotic synchronization at the receiving end. However, DCSK systems are transmit-reference structures, which means that half the symbol period of the system is required for transmitting the reference signal, which results in a low data rate and energy efficiency of DCSK. In addition, the reference information and the information-bearing signal can be adversely affected by channel noise, which degrades Bit Error Rate (BER) performance of the DCSK system. Therefore, many scholars have improved the DCSK scheme to increase data rate and energy efficiency.
In order to increase the data rate, a Quadrature Chaos Shift Keying (QCSK) system is proposed, which performs a Quadrature phase Shift Keying (qpsk) modulation on a reference signal and its hilbert transform, so that the system obtains twice the data rate compared with a DCSK system under the same bandwidth consumption. Inspired by this, the document (l.wang, g.cai, and g.r.chen, "Design and performance analysis of a new multiple resolution M-ary differential shift communication system," IEEE trans.wireless communication, vol.14, No.9, pp.5197-5208, sep 2015.) proposes a generalized multiple DCSK (M-ary DCSK) system, which can further improve the data rate of the system by adjusting the modulation order. However, as the modulation order increases, the BER performance of the multivariate DCSK system may decrease. In order to improve the data rate of the system without sacrificing BER performance, a multi-carrier DCSK (MC-DCSK) system is proposed, which uses a predefined sub-carrier for transmitting a reference signal and then uses the remaining sub-carriers for transmitting a multi-channel information-carrying signal. However, the MC-DCSK system has the problems of complex matched filtering and complex hardware implementation. In recent years, a Multicarrier chaotic Shift Keying (MC-CSK) system has also been proposed. The scheme utilizes Gram-Schmidt algorithm to generate a series of normalized orthogonal chaotic signals, and then one of the signals is selected as an information bearing signal through mapping bits. In other words, in the MC-CSK system, the information bits are implicitly carried by the specific index of the reference signal, and this design achieves the improvement of the data rate and BER performance. However, the reference signal in the above system is affected by channel fading and distortion, and channel noise still remains a big problem limiting the performance of the system.
To address this problem, many researchers have proposed many effective solutions in transmitter signal design. For example, a Short Reference DCSK (SR-DCSK) system that maximally shortens a Reference signal to reduce adverse effects of channel noise on the Reference signal. On the other hand, the Noise Reduction DCSK (Noise Reduction DCSK, NR-DCSK) system proposed by the literature (g.kaddoum and e.soujeri, "NR-DCSK: a Noise Reduction differential Noise shift keying system," IEEE trans. circuits system, II, exp. briefs, vol.63, No.7, pp.648-652, jul.2016) first connects several identical signals in series to construct a new reference signal, and then uses a moving average filter with the same length as the initial chaotic signal to respectively average the received reference signal and information-carrying signal, thereby greatly reducing the influence of the channel Noise on the system performance. Inspired by this, the subcarrier assisted MC-DCSK (SA-MC-DCSK) system proposed by the literature (h.yang, g. -p.jiang, w.k.s.tang, g.chen, and y. — c.lai, "Multicarrier differential chain shift keying system with Subcarriers Allocation for noise reduction," IEEE trans. circuits system ", II, exp.briefs, vol.65, No.11, pp.1733-1737, nov.2018) transmits the same reference signal using multiple Subcarriers and averages these received contaminated reference signals at the receiving end to reduce noise and thereby improve the performance of the system.
In addition, another method for effectively solving the noise of the reference signal is to perform Iterative design on a system Receiver, and a multi-carrier DCSK Iterative Receiver (MC-DCSK-IR) updates the reference signal by adopting a correlation value between the received reference signal and the information-bearing signal as a weight factor. The scheme can suppress the noise in the reference signal under the condition of not changing a system transmitter, thereby obtaining the improvement of the error rate performance. But the scheme only updates the reference signal to reduce channel distortion and suppress noise, the noise in the information-carrying signal is not processed, and the multi-channel information-carrying signal in the MC-DCSK-IR system contains more channel noise. Viewed from another perspective, the weight factors obtained in MC-DCSK-IR systems depend on the information-bearing signal containing more noise, and therefore cannot completely suppress the noise in the reference signal even if the updating process continues indefinitely.
Disclosure of Invention
The invention aims to provide a multi-carrier multi-element differential chaotic shift keying noise suppression system and a method, which can reduce the influence of channel noise in a reference signal and an information bearing signal of a system and further improve the BER performance of the system aiming at the problems that the conventional multi-carrier multi-element differential chaotic shift keying system is adversely affected by noise under a wireless channel.
The multi-carrier multi-element differential chaotic shift keying noise suppression system comprises a transmitting end and a receiving end;
the transmitting end comprises a chaotic signal generator, a serial/parallel converter, a bit/symbol converter, a multi-element DCSK modulator, a pulse shaping filter, a multiplier and an adder;
the chaotic signal generator is used for generating a chaotic signal c ═ c with the length theta1,c2,...,cθ]The chaotic signal is respectively matched with a reference Walsh code WRAnd mutually orthogonal Walsh codes WxAnd WyMultiplying, wherein the former part is transmitted to a pulse shaping filter to obtain a reference signal, and the latter part is transmitted to a multi-element DCSK modulator;
the serial/parallel converter is used for generating a U-path parallel bit data stream signal from the transmitting bit data stream signal through the serial/parallel converter;
the bit/symbol converter is used for converting a bit data stream into a symbol data stream;
the multi-element DCSK modulator is used for converting chaotic signals c and mutually orthogonal Walsh codes WxAnd WyThe symbol data stream is modulated by the product of (a) to generate a modulated signal, and the signal is transmitted to a pulse shaping filter;
the pulse shaping filter is used for filtering the signal to obtain a reference signal and an information bearing signal;
the adder is used for adding the reference signals modulated to different subcarriers and the information bearing signals to obtain transmission signals and transmitting the transmission signals to a wireless channel;
the receiving end comprises a matched filter, a sampling module, an averaging module, a noise suppression module and a multi-element DCSK modulator;
the matched filter is used for performing matched filtering on a signal obtained by multiplying a received signal r (t) by each subcarrier, and extracting a reference signal and an information bearing signal from each frequency band of the subcarrier;
the sampling module is used for sampling the extracted reference signal and information bearing signal and converting an analog signal into a corresponding digital signal;
the averaging module is used for averaging the sampling signals processed by different Walsh codes to obtain an averaged reference signal rRAnd in-phase component of information-bearing signal
Figure BDA0002658732860000031
And the orthogonal component
Figure BDA0002658732860000032
And transmitting to a noise suppression module;
the noise suppression module is used for suppressing the noise of the reference signal rRAnd in-phase component of information-bearing signal
Figure BDA0002658732860000033
And the orthogonal component
Figure BDA0002658732860000034
Form aMatrix B ofxAnd ByApplying a noise suppression algorithm to obtain an updated low-noise reference signal and an updated information bearing signal;
the multi-element DCSK demodulator is used for demodulating the updated low noise reference signal and the information bearing signal to obtain information bits.
The multi-carrier multi-element differential chaotic shift keying noise suppression method comprises the following steps:
1) the receiver multiplies the received signal r (t) affected by multipath fading and additive white Gaussian noise by a Walsh code and obtains an averaged reference signal r after an averaging moduleRIn-phase component of an information-bearing signal
Figure BDA0002658732860000041
And the orthogonal component
Figure BDA0002658732860000042
Thereby obtaining an initial matrix BxAnd By；
2) According to an initial matrix B in a noise suppression modulexAnd ByInitializing the updating times N;
3) and a two-layer nested loop iteration is used in the noise suppression module to update the weight factor, so that the noise suppression of the reference signal and the information bearing signal is realized.
In step 1), the signal r (t) comprises a reference signal and U information-carrying signals, and the received signal r (t) and the Walsh code are multiplied by using the orthogonality of the Walsh code, and the multiplied signal is averaged by an averaging module to obtain an averaged reference signal rRIn-phase component of an information-bearing signal
Figure BDA0002658732860000043
And the orthogonal component
Figure BDA0002658732860000044
The initial matrix BxAnd ByThe definition is as follows:
Figure BDA0002658732860000045
in step 2), the initialization comprises the following steps:
(1) defining a matrix of updated low noise reference signals and information-bearing signals in the ith iteration as
Figure BDA0002658732860000046
And
Figure BDA0002658732860000047
order to
Figure BDA0002658732860000048
Initialization is performed.
(2) The initial decision variable Z0 is obtained as follows in equation (2).
Figure BDA0002658732860000049
(3) Information bits are acquired using a multivariate DCSK demodulator, namely:
Figure BDA00026587328600000410
in step 3), iteratively updating the weight factor using a two-layer nested loop comprises the following steps:
(1) matrix derived in the i-1 st iteration
Figure BDA00026587328600000411
And
Figure BDA00026587328600000412
are multiplied by the jth row of
Figure BDA00026587328600000413
And
Figure BDA00026587328600000414
thereby obtaining a product matrix KxAnd KyThen, againWill KxAnd KyIs set to 0, i.e. the matrix
Figure BDA00026587328600000415
The j-th row of (a) is not in accordance with the matrix
Figure BDA00026587328600000416
Is multiplied by the jth column of (1), matrix
Figure BDA00026587328600000417
The j-th row of (a) is not in accordance with the matrix
Figure BDA00026587328600000418
Column j of (d);
(2) obtaining the weight factor G of the reference signal and the different information bearing signals according to the following formula (2)xAnd GyWherein
Figure BDA0002658732860000051
Denotes a kronecker product,. indicates a hadamard product,. 11×θAn identity matrix of size 1 × θ is shown.
Figure BDA0002658732860000052
(3) Will matrix GxAnd GyThe different row sums of (a) are averaged to get the jth row of the updated matrix, i.e.,
Figure BDA0002658732860000053
wherein sum (-) represents the sum of each row element;
(4) the updated decision variable Z is obtained as shown in the following equation (4)i；
Figure BDA0002658732860000054
(5) Information bits are acquired using a multivariate DCSK demodulator, namely:
Figure BDA0002658732860000055
(6) according to the following formula (5) pair
Figure BDA0002658732860000056
And
Figure BDA0002658732860000057
normalizing to obtain a normalized matrix
Figure BDA0002658732860000058
And
Figure BDA0002658732860000059
wherein norm (·) represents a norm taking operation;
Figure BDA00026587328600000510
(7) calculating the maximum difference value between the normalization matrixes obtained in two adjacent iterations, and judging whether the iteration can be stopped; is determined promptly
Figure BDA00026587328600000511
And
Figure BDA00026587328600000512
whether all are less than a set threshold value; if both terms are smaller than the set threshold value, the weighting factor is represented to contain all prior information in the reference signal and the information bearing signal, the iteration is stopped at the moment, and if not, the next iteration is carried out.
The invention has the following beneficial effects:
in the invention, the correlation coefficient of the received reference signal and the information bearing signal is used as a weight factor at a receiving end, then the weight factor is used as feedback to update the previous reference signal and the previous information bearing signal and inhibit noise in a transmission signal, and finally, the validity of the proposed algorithm is verified by utilizing computer simulation. The result shows that the combined transceiving noise suppression algorithm of the multi-carrier multi-element differential chaotic shift keying system can obviously reduce the noise in the transmission signal under an additive white Gaussian noise channel and a multipath fading channel, thereby improving the error rate performance of the system. The combined transceiving noise suppression algorithm of the multi-carrier multi-element differential chaotic shift keying system is used for suppressing channel noise in a reference signal and an information bearing signal, and the noise in a transmission signal is remarkably reduced under the condition of not sacrificing energy efficiency, so that the BER performance of the system is improved, and the design has wide application prospect in future wireless communication application.
Drawings
Fig. 1 is a block diagram of a multi-carrier multivariate differential shift keying noise suppression (JTR-NS-MC-MDCSK) system.
Fig. 2 is a graph comparing BER performance of the JTR-NS-MC-MDCSK system and the MC-DCSK-IR system under AWGN and CM2 channels under the condition that the number U of the same information subcarriers is 30.
FIG. 3 shows the number of transmitted bits per symbol NtPlot of BER performance versus AWGN and CM1 channels for JTR-NS-MC-MDCSK system and MC-DCSK-IR system with 10 identical.
FIG. 4 shows the number of transmitted bits per symbol NtPlots of BER performance versus AWGN and CM2 channels for JTR-NS-MC-MDCSK systems, MC-DCSK systems, MC-CSK systems, and SA-MC-DCSK systems for the same 24.
Detailed Description
In order to make the technical means, the creation features, the achievement purposes and the effects of the invention easy to understand, the following embodiments are further described with the attached drawings.
FIG. 1 is a block diagram of a JTR-NS-MC-MDSK system. The system comprises a transmitting end and a receiving end. The transmitting end comprises a chaotic signal generator, a serial/parallel converter, a bit/symbol converter, a multi-element DCSK modulator, a pulse shaping filter, a multiplier and an adder, and the receiving end comprises a matched filter, a sampling module, an averaging module, a noise suppression module and the multi-element DCSK modulator.
The specific working process of the system is as follows:
at the transmitting end, one subcarrier is used for transmitting reference signalsAnd U subcarriers are used for transmitting multivariate information. The transmitted reference signal is
Figure BDA0002658732860000061
The information bearing signal is
Figure BDA0002658732860000062
The transmission signal of the transmitting end can be expressed as:
Figure BDA0002658732860000063
wherein: c ═ c1,c2,...,cθ]Is a chaotic signal with the length theta; w is aR＝[wR,1,wR,2,...,wR,P]For reference Walsh codes of length P, similarly wxAnd wyTwo different Walsh code sequences for carrying the in-phase and quadrature components of the constellation symbols, respectively; a isuAnd buRepresenting the inphase and quadrature components of the u-th multivariate constellation symbol, fuIs the frequency of the u-th subcarrier. Generating a chaotic reference signal using logical mapping: c. Cj+1＝1-2cj 2(j ═ 1, 2.). The length P θ of one symbol period of the system is defined as the spreading factor of the system, i.e., β ═ P θ.
When the transmission signal is affected by multipath fading and AWGN during transmission, the signal received by the receiving end at this time can be represented as:
Figure BDA0002658732860000071
wherein L, λlAnd τlRepresenting the number of multipaths of the channel, the channel coefficient and the delay of the l-th path, respectively, η (t) represents AWGN, whose mean is zero and variance is N0/2. Furthermore, the channel coefficients of each path obey the rayleigh distribution and remain constant over the transmission symbol period. In particular, when L ═ 1, λ l1 and τlWhen 0, the channel degrades to an AWGN channel.
At the receiving end, the signals on each subcarrier are separated firstly, then the orthogonality of Walsh codes is utilized to carry out the Crohn's product operation on the received signals, and then the results are averaged to obtain the average reference signal rRIn-phase component of an information-bearing signal
Figure BDA0002658732860000072
And the orthogonal component
Figure BDA0002658732860000073
Respectively, as follows:
rR＝[rR,1,rR,2,...,rR,θ] (8)
Figure BDA0002658732860000074
Figure BDA0002658732860000075
wherein:
Figure BDA0002658732860000076
the signal design for averaging the received reference signal and information-bearing signal can suppress the adverse effect of noise, thereby enhancing the robustness of the system and embodying the noise suppression of the transmitting end.
Storing the obtained signals in matrix B respectivelyxAnd ByThe expression (1) is shown in (1).
Subsequently using the initial matrix BxAnd ByAnd initializing the initial signal by iteration number N. Reuse formula
Figure BDA0002658732860000077
Obtaining an initial decision variable Z0Thereafter, information bits are acquired using a multivariate DCSK demodulator.
And then updating the weight factors and the decision variables by using a nested loop to realize noise suppression of the reference signals and the information bearing signals. In the ith iteration, the following steps are included:
(1) matrix derived in the i-1 st iteration
Figure BDA0002658732860000078
And
Figure BDA0002658732860000079
are multiplied by the jth row of
Figure BDA00026587328600000710
And
Figure BDA00026587328600000711
thereby obtaining a product matrix KxAnd KyThen, K is addedxAnd KyIs set to 0, i.e. the matrix
Figure BDA00026587328600000712
The j-th row of (a) is not in accordance with the matrix
Figure BDA00026587328600000713
Is multiplied by the jth column of (1), matrix
Figure BDA00026587328600000714
The j-th row of (a) is not in accordance with the matrix
Figure BDA00026587328600000715
Column j of (d);
(2) obtaining the weight factor G of the reference signal and different information bearing signals according to the formula (2)xAnd Gy。
(3) Will matrix GxAnd GyThe different row sums of (a) are averaged to get the jth row of the updated matrix, i.e.,
Figure BDA0002658732860000081
(4) obtaining an updated decision variable Z according to equation (4)i。
(5) Information bits are acquired using a multivariate DCSK demodulator.
(6) According to the formula (5) to
Figure BDA0002658732860000082
And
Figure BDA0002658732860000083
and (6) normalizing.
(7) And calculating the maximum difference value between the normalization matrixes obtained in the two adjacent iterations, and judging whether the iteration can be stopped. Is determined promptly
Figure BDA0002658732860000084
And
Figure BDA0002658732860000085
whether all are less than a set threshold value; if both terms are smaller than the set threshold value, the weighting factor is represented to contain all prior information in the reference signal and the information bearing signal, the iteration is stopped at the moment, otherwise, the next iteration is carried out, and the step (1) is returned.
The invention provides a joint transmit-receive noise suppression (JTR-NS-MC-MDSK) method of a multi-carrier multi-element differential chaotic shift keying system. To better clarify its effectiveness, some computer simulation results are given. The fading channel used in the simulation is a three-path rayleigh fading channel, wherein the channel fading coefficients of the CM1 channel are:
Figure BDA0002658732860000086
the channel fading coefficients of the CM2 channel are:
Figure BDA0002658732860000087
multipath delays of both channels are tau1＝0，τ 21 and τ3＝2。
Fig. 2 compares BER performances of the JTR-NS-MC-MDCSK system and the MC-DCSK-IR system under AWGN and CM2 channels in the case where the number of information subcarriers U is 30. The channel fading coefficient of the CM2 channel is
Figure BDA0002658732860000088
Corresponding multipath delays of tau respectively1＝0，τ 21 and τ 32. Other simulation parameters of the system are respectively the iteration number N equal to 1, the modulation order M equal to 4, and the spreading factor β equal to 400. It can be seen from the graph that the BER performance of the JTR-NS-MC-MDCSK system is better than that of the MC-DCSK-IR system when N ═ 1. Specifically, it is up to 10 in AWGN channel-4The performance gain of JTR-NS-MC-MDSK is close to 5dB compared with that of MC-DCSK-IR system.
FIG. 3 compares the number of bits transmitted N per symboltThe BER performance of JTR-NS-MC-MDCSK and MC-DCSK-IR systems under AWGN and CM1 channels under the same condition of 10. The channel fading coefficient of the CM1 channel is
Figure BDA0002658732860000089
Figure BDA00026587328600000810
Corresponding multipath delays of tau respectively1＝0，τ 21 and τ 32. In the simulation, the number of iterations and spreading factor of the two systems are the same, N-1 and β -400, respectively. In a JTR-NS-MC-MDSK system, the modulation order M is 4, and the number of subcarriers U is 5; in the MC-DCSK-IR system, U is 10. The total number of transmitted bits for both systems in one symbol period is 10. Since the MC-DCSK-IR only suppresses noise in the reference signal and not in the information-carrying signal, and the proposed JTR-NS-MC-MDSK system performs noise suppression on both the reference signal and the information-carrying signal, the JTR-NS-MC-MDSK system has better BER performance than the MC-DCSK-IR system. As can be seen from FIG. 3, the channel of AWGN is reached to 10-5The BER of the system is lower than the signal-to-noise ratio required by the MC-DCSK-IR system by more than 3.5 dB.
FIG. 4 compares the number of bits transmitted N per symboltThe BER performance of JTR-NS-MC-MDCSK, MC-DCSK, MC-CSK and SA-MC-DCSK systems under AWGN and CM2 channels with 24 identical. In a JTR-NS-MC-MDSK system, the iteration number and the modulation order are respectively N-1 and M-2; in SA-MC-DCSK system, reference number of subcarriersAnd the number of information subcarriers are both 24. It can be seen from the figure that the SA-MC-DCSK has better BER performance than the MC-DCSK and MC-CSK systems, mainly because the reference diversity of the SA-MC-DCSK system enhances the robustness of the system in the face of noise interference. However, this performance improvement needs to be at the cost of energy efficiency, since the SA-MC-DCSK system needs to share half the symbol energy when transmitting the reference signal. In contrast, the JTR-NS-MC-MDSK system can have BER performance more than 6dB better than that of the MC-DCSK system and the MC-CSK system without sacrificing energy efficiency.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. The combined transceiving noise suppression algorithm of the multi-carrier multi-element differential chaotic shift keying system updates the previous reference signal and information bearing signal by using the correlation coefficient of the received reference signal, the reference signal and the information bearing signal as a weight factor at a receiving end so as to realize the suppression of channel noise. Experiments show that the combined transceiving noise suppression algorithm of the multi-carrier multi-element differential chaotic shift keying system can obviously reduce the noise in transmission signals under an additive white Gaussian noise channel and a multipath fading channel, thereby improving the error rate performance of the system.

Claims (2)

1. A multi-carrier multi-element differential chaotic shift keying noise suppression system is characterized by comprising a transmitting end and a receiving end;
the transmitting end comprises a chaotic signal generator, a serial/parallel converter, a bit/symbol converter, a multi-element DCSK modulator, a pulse shaping filter, a multiplier and an adder; the receiving end comprises a matched filter, a sampling module, an averaging module, a noise suppression module and a multi-element DCSK demodulator;
the chaotic signal generator is used for generating a chaotic signal c ═ c with the length theta1,c2,...,cθ]The chaotic signal is respectively matched with a reference Walsh code WRAnd mutually orthogonal Walsh codes WxAnd WyMultiplication, the previous part being passed to pulse shaping filteringThe device obtains a reference signal, and the latter part is transmitted to a multi-element DCSK modulator;
the serial/parallel converter is used for generating a U-path parallel bit data stream signal from the transmitting bit data stream signal through the serial/parallel converter;
the bit/symbol converter is used for converting a bit data stream into a symbol data stream;
the multi-element DCSK modulator is used for converting chaotic signals c and mutually orthogonal Walsh codes WxAnd WyThe symbol data stream is modulated by the product of (a) to generate a modulated signal, and the signal is transmitted to a pulse shaping filter;
the pulse shaping filter is used for filtering the signal to obtain a reference signal and an information bearing signal;
the adder is used for adding the reference signals modulated to different subcarriers and the information bearing signals to obtain transmission signals and transmitting the transmission signals to a wireless channel;
the matched filter is used for performing matched filtering on a signal obtained by multiplying a received signal r (t) by each subcarrier, and extracting a reference signal and an information bearing signal from each frequency band of the subcarrier;
the sampling module is used for sampling the extracted reference signal and information bearing signal and converting an analog signal into a corresponding digital signal;
the averaging module is used for averaging the sampling signals processed by the Walsh codes to obtain an averaged reference signal rRAnd in-phase component of information-bearing signal
Figure FDA0003247737730000011
And the orthogonal component
Figure FDA0003247737730000012
And transmitting to a noise suppression module; wherein
Figure FDA0003247737730000013
And
Figure FDA0003247737730000014
an in-phase component and a quadrature component representing the received information-bearing signal transmitted by the u-th subcarrier;
the noise suppression module is used for suppressing the noise of the reference signal rRAnd in-phase component of information-bearing signal
Figure FDA0003247737730000015
And the orthogonal component
Figure FDA0003247737730000016
Formed matrix BxAnd ByObtaining an updated low-noise reference signal and an updated information bearing signal by applying a noise suppression method;
the multi-element DCSK demodulator is used for demodulating the updated low noise reference signal and the information bearing signal to obtain information bits.
2. The multi-carrier multi-element differential chaotic shift keying noise suppression method is characterized by comprising the following steps of:
1) the receiver multiplies the received signal r (t) affected by multipath fading and additive white Gaussian noise by a Walsh code and obtains an averaged reference signal r after an averaging moduleRIn-phase component of an information-bearing signal
Figure FDA0003247737730000021
And the orthogonal component
Figure FDA0003247737730000022
Thereby obtaining an initial matrix BxAnd ByWherein u represents the u-th subcarrier;
the signal r (t) comprises a reference signal and U information-bearing signals, the orthogonality of Walsh codes is utilized to multiply the received signal r (t) and the Walsh codes, and the average signal r is obtained after an averaging moduleRIn-phase component of an information-bearing signal
Figure FDA0003247737730000023
And the orthogonal component
Figure FDA0003247737730000024
The initial matrix BxAnd ByThe definition is as follows:
Figure FDA0003247737730000025
2) according to an initial matrix B in a noise suppression modulexAnd ByInitializing the updating times N;
the initialization comprises the following steps:
(1) defining a matrix of updated low noise reference signals and information-bearing signals in the ith iteration as
Figure FDA0003247737730000026
And
Figure FDA0003247737730000027
order to
Figure FDA0003247737730000028
Carrying out initialization;
(2) obtaining an initial decision variable Z according to the following formula (2)0；
Figure FDA0003247737730000029
(3) Information bits are acquired using a multivariate DCSK demodulator, namely:
Figure FDA00032477377300000210
3) using two layers of nested loops in a noise suppression module to iteratively update the weight factors to realize noise suppression on the reference signals and the information bearing signals;
the method for iteratively updating the weight factors by using the two layers of nested loops comprises the following steps:
(1) matrix derived in the i-1 st iteration
Figure FDA00032477377300000211
And
Figure FDA00032477377300000212
are multiplied by the jth row of
Figure FDA00032477377300000213
And
Figure FDA00032477377300000214
thereby obtaining a product matrix KxAnd KyThen, K is addedxAnd KyIs set to 0, i.e. the matrix
Figure FDA00032477377300000215
The j-th row of (a) is not in accordance with the matrix
Figure FDA00032477377300000216
Is multiplied by the jth column of (1), matrix
Figure FDA00032477377300000217
The j-th row of (a) is not in accordance with the matrix
Figure FDA00032477377300000218
Column j of (d);
(2) obtaining the weight factor G of the reference signal and the different information bearing signals according to the following formula (3)xAnd GyWherein
Figure FDA00032477377300000219
Denotes a kronecker product,. indicates a hadamard product,. 11×θAn identity matrix of size 1 × θ;
Figure FDA00032477377300000220
wherein, KxAs a matrix in the ith iteration
Figure FDA00032477377300000221
J th row and matrix of
Figure FDA00032477377300000222
And setting the element of the jth column of the 1 st row to 0; kyAs a matrix in the ith iteration
Figure FDA0003247737730000031
J th row and matrix of
Figure FDA0003247737730000032
And setting the element of the jth column of the 1 st row to 0;
(3) will matrix GxAnd GyThe different row sums of (a) are averaged to get the jth row of the updated matrix, i.e.,
Figure FDA0003247737730000033
wherein sum (-) represents the sum of each row element;
(4) the updated decision variable Z is obtained as shown in the following equation (4)i；
Figure FDA0003247737730000034
(5) Information bits are acquired using a multivariate DCSK demodulator, namely:
Figure FDA0003247737730000035
(6) according to the following formula (5) pair
Figure FDA0003247737730000036
And
Figure FDA0003247737730000037
normalizing to obtain a normalized matrix
Figure FDA0003247737730000038
And
Figure FDA0003247737730000039
wherein norm (·) represents a norm taking operation;
Figure FDA00032477377300000310
(7) calculating the maximum difference value between the normalization matrixes obtained in two adjacent iterations, and judging whether the iteration can be stopped; is determined promptly
Figure FDA00032477377300000311
And
Figure FDA00032477377300000312
whether all are less than a set threshold value; if both terms are smaller than the set threshold value, the weighting factor is represented to contain all prior information in the reference signal and the information bearing signal, the iteration is stopped at the moment, and if not, the next iteration is carried out.
CN202010897102.3A 2020-08-31 2020-08-31 Multi-carrier multi-element differential chaotic shift keying noise suppression system and method Expired - Fee Related CN111988253B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010897102.3A CN111988253B (en) 2020-08-31 2020-08-31 Multi-carrier multi-element differential chaotic shift keying noise suppression system and method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010897102.3A CN111988253B (en) 2020-08-31 2020-08-31 Multi-carrier multi-element differential chaotic shift keying noise suppression system and method

Publications (2)

Publication Number Publication Date
CN111988253A CN111988253A (en) 2020-11-24
CN111988253B true CN111988253B (en) 2021-10-29

Family

ID=73440534

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010897102.3A Expired - Fee Related CN111988253B (en) 2020-08-31 2020-08-31 Multi-carrier multi-element differential chaotic shift keying noise suppression system and method

Country Status (1)

Country Link
CN (1) CN111988253B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117240673B (en) * 2023-11-16 2024-03-15 南京邮电大学 Multi-carrier index differential chaos shift keying modem and method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106817330A (en) * 2017-02-04 2017-06-09 厦门大学 The multi-system difference chaotic shift keying modulation demodulator of combination code subscript modulation

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9966991B2 (en) * 2015-07-28 2018-05-08 John David Terry Method and apparatus for secure network access and group membership in a digital chaos cooperative network
CN106549894B (en) * 2016-11-18 2019-08-16 厦门大学 The code of combination code subscript modulation is multiplexed difference chaotic modem
CN110417695B (en) * 2019-08-07 2020-07-03 厦门大学 Reference diversity design algorithm of multistage code shift differential chaotic shift keying system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106817330A (en) * 2017-02-04 2017-06-09 厦门大学 The multi-system difference chaotic shift keying modulation demodulator of combination code subscript modulation

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
An M-ary Code Shifted Differential Chaos Shift Keying Scheme;Yunsheng Tan, .etc;《2017 23rd Asia-Pacific Conference on Communications (APCC)》;20171213;全文第2章，附图1、3 *
General Iterative Receiver Design for Enhanced Reliability in Multi-Carrier Differential Chaos Shift Keying Systems;Bingjun Chen, .etc;《IEEE TRANSACTIONS ON COMMUNICATIONS》;20190906;第67卷(第11期);全文 *
Guofa Cai, .etc.Multi-Carrier M-ary DCSK System With Code Index Modulation: An Efficient Solution for Chaotic Communications.《IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING》.2019,第13卷(第6期),全文第2、4章，附图1、3. *
Multi-Carrier M-ary DCSK System With Code Index Modulation: An Efficient Solution for Chaotic Communications;Guofa Cai, .etc;《IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING》;20190501;第13卷(第6期);全文第2、4章，附图1、3 *

Also Published As

Publication number Publication date
CN111988253A (en) 2020-11-24

Similar Documents

Publication Publication Date Title
AU731266B2 (en) Data transmission method and radio system
US7492830B2 (en) Signal receiving method in MIMO system and device therefor
KR101053556B1 (en) Equal GE power control for uplink MC-CDMA with MMS continuous interference cancellation
CN113206813B (en) OFDM system peak-to-average power ratio suppression method based on improved selective mapping method
KR100906948B1 (en) Reception of multicarrier spread-spectrum signals
CN112003804B (en) Multipath multivariate differential chaotic shift keying iterative receiving method
CN112003805B (en) Joint time-frequency index modulation multimode differential chaos shift keying modulation and demodulation method
CN110417695B (en) Reference diversity design algorithm of multistage code shift differential chaotic shift keying system
Chitra et al. Performance enhancement of generalized frequency division multiplexing with RF impairments compensation for efficient 5G wireless access
CN114039825A (en) SIMO-HPO-CDSK communication method based on Rayleigh fading channel
CN101467380B (en) Method and apparatus for estimating noise varience
JP2003249911A (en) Pre-distortion method for telecommunication system and transmitter for mobile terminal of mc-cdma telecommunication system
CN111988253B (en) Multi-carrier multi-element differential chaotic shift keying noise suppression system and method
Hasan Design and analysis of grouping subcarrier index modulation for differential chaos shift keying communication system
US20060256894A1 (en) Frequency offset compensation in radio receiver
CN116915554A (en) Millimeter wave LOS-MIMOOOFDM phase noise estimation compensation method and system
Dinis et al. IB‐DFE receivers with space diversity for CP‐assisted DS‐CDMA and MC‐CDMA systems
Na et al. PAPR reduction scheme for FBMC-OQAM without side information
CN111245589B (en) Pilot frequency superposition channel estimation method
Gomes et al. Iterative frequency domain equalization for single carrier signals with magnitude modulation techniques
Al‐Saggaf et al. Machine Learning Aided Channel Equalization in Filter Bank Multi‐Carrier Communications for 5G
Ni et al. Cochannel interference suppression for coded OFDM systems over frequency-selective slowly fading channels
JP4187555B2 (en) Communication system and receiving apparatus
Harbi et al. DWT-MCM based OQAM modulation scheme in the downlink transmission of wireless systems
Cai et al. A spectrum-efficient M-ary correlation delay shift keying scheme for non-coherent chaotic communications

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20211029