CN111817993A - Improved short reference correlation delay shift keying communication scheme - Google Patents

Improved short reference correlation delay shift keying communication scheme Download PDF

Info

Publication number
CN111817993A
CN111817993A CN202010515541.3A CN202010515541A CN111817993A CN 111817993 A CN111817993 A CN 111817993A CN 202010515541 A CN202010515541 A CN 202010515541A CN 111817993 A CN111817993 A CN 111817993A
Authority
CN
China
Prior art keywords
information
scheme
signal
cdsk
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.)
Pending
Application number
CN202010515541.3A
Other languages
Chinese (zh)
Inventor
贺利芳
吴雪霜
陈俊
匡政泽
张刚
张天骐
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.)
Chongqing University of Post and Telecommunications
Original Assignee
Chongqing University of Post and Telecommunications
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 Chongqing University of Post and Telecommunications filed Critical Chongqing University of Post and Telecommunications
Priority to CN202010515541.3A priority Critical patent/CN111817993A/en
Publication of CN111817993A publication Critical patent/CN111817993A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
    • H04L9/001—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols using chaotic signals

Landscapes

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

Abstract

The invention discloses an improved short reference correlation delay shift keying communication scheme, belonging to the technical field of communication. At an information sending end, a time reversal technology is combined with a traditional related delay shift keying (CDSK) modulation technology, so that the new scheme can transmit 2-bit information in one frame, the length of a reference signal is shortened, the information transmission rate is effectively improved, in addition, the reference signal and the information signal are respectively transmitted by utilizing two orthogonal carriers, the interference between the signals is eliminated, and the error code performance of the system is improved. At the demodulation end, the scheme still adopts a simple noncoherent demodulation mode to decode the information bits. Compared with CDSK, the scheme has better error code performance and information transmission rate, so it has more practical application value in communication system.

Description

Improved short reference correlation delay shift keying communication scheme
Technical Field
The invention aims to design an improved short-reference correlation delay shift keying communication scheme, which improves the traditional Correlation Delay Shift Keying (CDSK) modulation technology to obviously improve the transmission rate and the error code new energy and greatly reduce the energy per bit.
Background
In the middle of the 19 th century, chaos first entered the field of view of scientists. In 1990, researchers in the American naval laboratory found the chaos synchronization phenomenon through experiments for the first time, and the breakthrough discovery provides possibility for applying the chaos theory to the communication field. Thereafter, many scholars at home and abroad begin to research and realize secret communication by using chaotic control and chaotic synchronization, and the application of the chaotic theory in the communication field is formally started. The chaotic signal is simple to generate, and has robustness, initial value sensitivity, randomness-like property and unpredictability, so that the chaotic signal has attractive application prospect and great practical value in the fields of information safety and communication.
Parlitz and Dedieu proposed a first chaotic digital modulation technique, Chaotic Shift Keying (CSK), in 1992 and 1993 respectively, and Kolumman et al, a successor, artificially overcome the threshold Shift problem of the CSK scheme during incoherent demodulation, and proposed a incoherent chaotic digital modulation technique, Difference Shift Keying (DCSK), in 1996. DCSK has good noise immunity and multipath fading resistance, but because it uses transmission-Reference (T-R) technique, half of the power is wasted in transmitting Reference signal without any information in one information frame, reducing transmission rate and system energy efficiency. To increase the bit transmission rate of the DCSK scheme, Sushchik et al proposed a Coherent Delay Shift Keying (CDSK) modulation scheme in 2000[1,2]. Different from the DCSK scheme, the CDSK scheme simultaneously transmits modulated chaotic signals carrying information and reference signals corresponding to other information bits. Because the reference signal does not need to be transmitted separately, the frequency band utilization rate of the CDSK scheme is improved, but the CDSK scheme transmits the sum of the current reference signal and the previous information signal, so that the intra-signal interference is introduced when the demodulation end carries out correlation operation, and the error code performance of the CDSK scheme is inferior to that of the DCSK scheme. Two typical systems in the field of DCSK and CDSK schemes chaos digital communication, and new schemes proposed in recent years are improved schemes proposed by numerous researchers aiming at the defects of the two typical schemes.
In summary, the present invention provides an improved short reference correlation delay shift keying (I-SR-CDSK) communication scheme for overcoming the defects of low information transmission rate and poor error performance of the CDSK modulation technique.
Disclosure of Invention
The invention provides an improved short reference correlation delay shift keying (I-SR-CDSK) communication scheme aiming at the problems of low transmission rate and poor error code performance of a CDSK modulation technology. The implementation method of the scheme provided by the invention comprises the following steps: at an information sending end, firstly, a chaos sequence with the length of R generated by a chaos signal generator is subjected to digital-to-analog conversion to obtain a continuous analog signal, the continuous analog signal is used as a reference signal, and the chaos sequence with the length of R is copied for P times to form a chaos sequence with the length of beta (beta is PR); then, performing digital-to-analog conversion on the chaos sequence with the length of beta and a chaos sequence with low correlation with the chaos sequence after time reversal to obtain two analog signals with low correlation, and respectively modulating 1bit data information and then adding the two analog signals to form an information signal; finally, the reference signal and the information signal are respectively modulated by two orthogonal carriers and added together to form a frame of transmission signal. At the demodulation end, the scheme adopts a non-coherent demodulation mode to decode information bits. Firstly, multiplying a received signal by a carrier cos (2 pi ft) and a carrier sin (2 pi ft), and recovering a reference sequence and an information sequence after the multiplication by a matched filter and sampling; then, the reference sequence and the information sequence carry out correlation operation, the correlation operation result is sent to a threshold decision device, and the symbol of the threshold decision device is judged to demodulate 1bit data information; and meanwhile, carrying out time reversal on the extracted reference sequence, then carrying out correlation operation on the reference sequence and the information sequence, sending the correlation result to another threshold decision device, and judging a symbol of the correlation result to demodulate another 1-bit data information. The decision criterion of the threshold decision device is as follows: the correlation value is greater than or equal to zero and is judged to be + 1; otherwise, the result is "-1".
The invention has the beneficial effects that: compared with the traditional CDSK scheme, the information transmission rate, the error code performance and the energy efficiency of the improved short-reference correlation delay shift keying (I-SR-CDSK) communication scheme provided by the invention are obviously improved.
Drawings
FIG. 1 is a diagram of a transmitter architecture for the I-SR-CDSK scheme of the present invention;
FIG. 2 is a diagram of a receiver architecture for the I-SR-CDSK scheme of the present invention;
fig. 3 is a graph comparing experimental values and simulated values of system BER for the present invention where R is 300 and P is 2;
FIG. 4 shows the BER of the system with E when R is 128,256,512 and P is 2 according to the present inventionb/N0A profile of change;
FIG. 5 shows the present invention where P is 2 and Eb/N0The relation curve between the system BER and R is 10dB,15dB and 18 dB;
fig. 6 is a graph comparing error performance curves of different systems when R is 256 and P is 2 according to the present invention.
Detailed Description
The invention is further described with reference to the following drawings and specific examples.
Fig. 1 shows a transmitter structure diagram of an I-SR-CDSK scheme. At a sending end, firstly, a chaotic signal generator generates a chaotic sequence x with the length of Ri,kReference sequence xi,kAfter D/A conversion, a continuous analog signal is obtained and used as a reference signal, and meanwhile, a reference sequence x is usedi,kRepeating the steps for P times to obtain a chaos sequence with the length of beta; then, the section of the copied chaotic sequence and a chaotic sequence with low correlation with the chaotic sequence obtained by time reversal are subjected to digital-to-analog conversion; the two analog signals then modulate the information bit b separately2k-1And information bit b2kThe signals are added together through an adder and then multiplied by a carrier cos (2 pi ft), and meanwhile, a reference signal is multiplied by a carrier-sin (2 pi ft); finally, the two paths of signals are added together by an adder to obtain a sending signal s (t) of the kth frame, and the sending signal s (t) can be expressed as:
Figure BDA0002529954380000041
wherein, x (t)Is a reference signal of length R, b2k-1And b2kRespectively representing information bits, xp(t) is an analog signal obtained by performing digital-to-analog conversion on the copied chaotic sequence,
Figure BDA0002529954380000042
and carrying out time reversal and then digital-to-analog conversion on the copied chaotic sequence to obtain an analog signal.
The average bit energy of the I-SR-CDSK scheme can be calculated by the formula (1) as follows:
Figure BDA0002529954380000043
fig. 2 shows a receiver structure diagram of the I-SR-CDSK scheme. The invention adopts a non-coherent demodulation mode to decode information bits at a demodulation end. Firstly, multiplying a received signal by a carrier cos (2 pi ft), then recovering a reference signal through a matched filter 2, sampling the reference signal, and then converting an analog signal into a digital signal so as to recover a reference sequence; similarly, the received signal is multiplied by the carrier-sin (2 π ft) and then restored to the information signal by the matched filter 1, and the information signal is sampled to realize the conversion from analog signal to digital signal, and then the information sequence is restored, wherein the sampling interval is iTcFor the convenience of theoretical derivation, let T c1 is ═ 1; then, the reference sequence and the information sequence are correlated for P times in the time with the length of R to obtain the information bit b2k-1Is determined by a decision variable Z2k-1The decision variable is sent to a threshold decision device, and the sign is decided, thus recovering the information bit b2k-1(ii) a After the reference sequence used in the demodulation process is time-reversed, the same demodulation operation is carried out, and the information bit b can be decoded2k。
The output of the receiving-end correlator is:
Figure BDA0002529954380000051
assuming that the signal is only affected by gaussian white noise during transmission, the signal r (t) received by the receiver can be represented as:
r(t)＝s(t)+ξ(t) (4)
where ξ (t) is zero as the mean value and the variance is N0White Gaussian noise of/2.
The available correlator output, eventually after substitution and reduction, can be expressed as:
Figure BDA0002529954380000052
Figure BDA0002529954380000061
Figure BDA0002529954380000062
Figure BDA0002529954380000063
in the same way, the following can be obtained:
Figure BDA0002529954380000064
Figure BDA0002529954380000065
Figure BDA0002529954380000066
Figure BDA0002529954380000067
the first term in equations (5) and (9) is the desired signal, and the second term and the third term are the interference terms. As can be seen from equations (7), (8), (11) and (12), these interferences mainly come from inter-signal interference (intra-signal interference) and noise interference terms (extra-signal interference) present in the system. Root of herbaceous plantThe information bit b can be recovered according to the following decision criterion2k-1And b2k：
Figure BDA0002529954380000068
Figure BDA0002529954380000069
Chaotic signal x in the present inventioni,kGenerated from Logistic mapping and normalized. Therefore, it has the following characteristics: e [ x ]i,k]＝0，
Figure BDA00025299543800000610
var[xi,k]＝1，
Figure BDA00025299543800000611
The error rate formula of the I-SR-CDSK system under the Gaussian channel is derived by using a Gaussian Approximation (GA) method. The second term and the third term in both the expression (5) and the expression (9) follow a gaussian distribution, and when the reference signal length R is large, the first term also approximately follows a gaussian distribution.
Simple calculations are performed on the terms in equation (5):
E[A]＝b2k-1PR (15)
E[B]＝E[C]＝0 (16)
E[Z2k-1]＝b2k-1PR (17)
var[A]＝0 (18)
Figure BDA0002529954380000071
Figure BDA0002529954380000072
Figure BDA0002529954380000073
Figure BDA0002529954380000074
where E [. cndot. ] represents a mathematical expectation operation and var [. cndot. ] represents a variance operation.
Assuming that the system transmits binary information with equal probability, the information bit b can be obtained by the equations (17), (21) and (22)2k-1The misjudgment probability is as follows:
Figure BDA0002529954380000075
similarly, information bit b2kThe false positive probability of (2) can also be expressed by the expression (24). Thus, the bit error rate of the system is:
Figure BDA0002529954380000081
as can be seen from the observation (24), the bit error rate of the system is subject to the parameters R, P and Eb/N0Influence when P and Eb/N0When the error rate is unchanged, an optimal R value is always present, so that the error code performance of the system is the best. Thus, let
Figure BDA0002529954380000082
The derivation of equation (25) is taken and the derivative is made equal to 0, resulting in the optimum value for R:
Figure BDA0002529954380000083
in equations (23) and (24), erfc (-) is a complementary error function, and
Figure BDA0002529954380000084
fig. 3 shows the system error when the reference signal length R is 300 and the number of copies P is 2Theoretical and experimental values of the rate (BER) with the signal-to-noise ratio Eb/N0The curve of the change. It can be seen from the curve in the figure that the theoretical value and the experimental value of the system bit error rate are basically consistent, and the correctness of the derivation of the theoretical bit error rate formula is proved. FIG. 4 shows a difference Eb/N0Under the condition, the system BER is a curve changing along with the R value. As can be seen from fig. 4, as R increases, the BER of the system tends to decrease and then increase, so that there must be an optimal R value to minimize the BER of the system. FIG. 5 shows the system BER against E for R of 128,256 and 512, respectivelyb/N0The curve of the change. From the graph of FIG. 5, it can be seen that as R (R > R)opt) The increase in value deteriorates the system BER performance, which is consistent with the curve of fig. 4. Fig. 6 is a graph comparing BER curves of the I-SR-CDSK system, the CDSK system, and the SR-DCSK system when the spreading factor is the same (β is 512). As can be seen from the comparison of FIG. 6, the performance of the I-SR-CDSK system is significantly better than that of the CDSK system, and slightly better than that of the SR-DCSK system. From the aspect of information transmission rate, the information transmission rate of the I-SR-CDSK system is obviously improved compared with that of the CDSK system and the SR-DCSK system.
The invention combines the time reversal technology with the traditional CDSK modulation technology and provides an improved short-reference related delay shift keying communication scheme so as to achieve the purposes of improving the error code performance and the information transmission rate and reducing the bit energy. Simulation results show that theoretical values are consistent with experimental values, and the derivation correctness of the theoretical error rate formula is proved. The invention is more practical in communication system.

Claims (3)

1. The scheme effectively improves the traditional Correlation Delay Shift Keying (CDSK) modulation technology, combines the time reversal technology with the CDSK modulation technology, enables the new scheme to transmit 2-bit information in one frame, shortens the length of a reference signal, and adopts two orthogonal carriers to respectively transmit the reference signal and an information signal, thereby eliminating the interference between the reference signal and the information signal. Compared with CDSK, the length of reference signal of improved short reference correlation delay shift keying (I-SR-CDSK) scheme is shortened to R (R ═ beta/P), and the length of information signal is kept unchanged. The improved scheme effectively improves the information transmission rate and the error code performance. At the demodulation end, the scheme adopts a non-coherent demodulation mode to decode information bits, firstly, a received signal is multiplied by a corresponding carrier, then, a reference sequence and an information sequence are restored after passing through a matched filter and sampling in sequence, then, the reference sequence and the corresponding information sequence are subjected to correlation operation, and finally, a threshold decision device is used for judging symbols of the correlation operation values, so that the information bits can be restored. The judgment criterion is as follows: the correlation value is larger than zero and is judged to be + 1; otherwise, the result is "-1".
2. The communication scheme according to claim 1, having the advantage that: the time reversal technology is applied to the scheme, the cross correlation between two information signals is reduced to a certain extent, and the reference signal and the information signal are respectively transmitted by adopting two orthogonal carriers, so that the interference between the reference signal and the information signal is completely eliminated, and the error rate is reduced; in addition, each frame of the scheme transmits 2-bit user information, and the length of the reference signal is shortened to R, so that the energy of each bit is greatly reduced, and the information transmission rate is improved.
3. The communication scheme according to claim 1, characterized by the advantage that: at the receiving end, the scheme adopts a non-correlation demodulation mode to recover the information bits, and the method has simple structure and low hardware cost.
CN202010515541.3A 2020-06-09 2020-06-09 Improved short reference correlation delay shift keying communication scheme Pending CN111817993A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010515541.3A CN111817993A (en) 2020-06-09 2020-06-09 Improved short reference correlation delay shift keying communication scheme

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010515541.3A CN111817993A (en) 2020-06-09 2020-06-09 Improved short reference correlation delay shift keying communication scheme

Publications (1)

Publication Number Publication Date
CN111817993A true CN111817993A (en) 2020-10-23

Family

ID=72844857

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010515541.3A Pending CN111817993A (en) 2020-06-09 2020-06-09 Improved short reference correlation delay shift keying communication scheme

Country Status (1)

Country Link
CN (1) CN111817993A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114826848A (en) * 2022-03-04 2022-07-29 重庆邮电大学 Communication method of enhanced high-efficiency short-parameter DCSK chaotic communication system

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106161310A (en) * 2016-07-21 2016-11-23 南京邮电大学 A kind of multicarrier difference chaotic shift keying modulation demodulation method and modem
CN107872412A (en) * 2016-09-27 2018-04-03 重庆邮电大学 A kind of energy-efficient difference chaotic communication system
CN109088717A (en) * 2018-10-24 2018-12-25 重庆邮电大学 Multi-user's chaos communications based on time reversal of multiple input single output
CN109347619A (en) * 2018-10-25 2019-02-15 重庆邮电大学 A kind of CD-DCSK chaos communications interfered between no signal
CN109412988A (en) * 2018-11-01 2019-03-01 重庆邮电大学 A kind of orthogonal multi-user's chaos shift keying communication plan
CN109600329A (en) * 2018-11-01 2019-04-09 重庆邮电大学 The efficient chaotic communication system of multi-system based on Walsh code
CN109802823A (en) * 2018-10-25 2019-05-24 重庆邮电大学 Multi output single input multicarrier correlation delay Keying scheme

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106161310A (en) * 2016-07-21 2016-11-23 南京邮电大学 A kind of multicarrier difference chaotic shift keying modulation demodulation method and modem
CN107872412A (en) * 2016-09-27 2018-04-03 重庆邮电大学 A kind of energy-efficient difference chaotic communication system
CN109088717A (en) * 2018-10-24 2018-12-25 重庆邮电大学 Multi-user's chaos communications based on time reversal of multiple input single output
CN109347619A (en) * 2018-10-25 2019-02-15 重庆邮电大学 A kind of CD-DCSK chaos communications interfered between no signal
CN109802823A (en) * 2018-10-25 2019-05-24 重庆邮电大学 Multi output single input multicarrier correlation delay Keying scheme
CN109412988A (en) * 2018-11-01 2019-03-01 重庆邮电大学 A kind of orthogonal multi-user's chaos shift keying communication plan
CN109600329A (en) * 2018-11-01 2019-04-09 重庆邮电大学 The efficient chaotic communication system of multi-system based on Walsh code

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114826848A (en) * 2022-03-04 2022-07-29 重庆邮电大学 Communication method of enhanced high-efficiency short-parameter DCSK chaotic communication system

Similar Documents

Publication Publication Date Title
CN108365945B (en) Differential chaotic shift keying modem and method based on two-way index modulation
US11075669B2 (en) M-ary differential chaos shift keying method based on chaotic shape-forming filter
CN108449297B (en) Phase separation differential chaos keying communication method based on hybrid system
CN113595951B (en) Differential chaotic phase shift keying communication method and system based on mixed index
CN102739322B (en) Remote underwater acoustic communication method based on soft-demodulation soft-decoding joint iteration
CN111756664B (en) Short reference carrier index differential chaotic shift keying modulation and demodulation method and system
CN112260972B (en) Equalization method based on bit field superimposed training sequence under symbol interference channel
CN102025669B (en) Short-wave data transmission method based on dual multisystem quasi-orthogonal spread-spectrum composite phase modulation
CN111770040A (en) Improved multi-user DCSK chaotic communication system
CN111988251A (en) Improved orthogonal multi-user differential chaotic communication system
CN110011947A (en) Modulator approach is eliminated in a kind of interference in super Nyquist Transmission system based on split-matrix
CN112003804A (en) Multipath multivariate differential chaotic shift keying iterative receiving method
CN111817993A (en) Improved short reference correlation delay shift keying communication scheme
CN114039825A (en) SIMO-HPO-CDSK communication method based on Rayleigh fading channel
CN113630356A (en) Fractional order multi-carrier multi-code shift multi-system differential chaotic shift keying modulation and demodulation method and modem
CN110324065B (en) Multi-user underwater acoustic communication method based on cyclic shift keying spread spectrum modulation
CN112422149A (en) I/Q dual-branch index modulation multi-sequence spread spectrum system and method
CN109672495B (en) Physical layer network coding method based on continuous phase modulation
CN106357383B (en) DC-DCSK secret communication system and analysis processing method
CN102202024A (en) Space-time continuous phase modulation (CPM) signal modulation and demodulation methods
CN115883298A (en) Underwater acoustic communication method based on Haar distribution domain coding diversity
CN115378461A (en) Simulation algorithm of time-hopping direct sequence spread spectrum signal
CN110995364B (en) Communication method for improving communication rate of double-differential spread spectrum underwater acoustic communication system
CN109802903B (en) Physical layer safety transmission method based on full duplex signal cancellation
Zhou et al. Noise reduction multi-carrier differential chaos shift keying system

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
WD01 Invention patent application deemed withdrawn after publication

Application publication date: 20201023

WD01 Invention patent application deemed withdrawn after publication