CN102340478A - Transform domain communication system and transmission signal producing method thereof - Google Patents
Transform domain communication system and transmission signal producing method thereof Download PDFInfo
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Abstract
The invention belongs to the field of communication technology and discloses a transform domain communication system. Aiming to the problem of high peak-to-average power ratio of the traditional transform domain communication system, a transmission end of the system disclosed by the invention comprises a soft amplitude limit module and a Fourier transform module; the threshold of a basic modulation waveform is set by the soft amplitude limit module and the amplitude of the basic modulation waveform is controlled in a low range through a signal circulating treatment so that a transmission signal with a low peak-to-average power ratio can be obtained, the nonlinear influence of a high-power amplifier on the transmission signal is reduced and the power amplifier efficiency of the amplifier is improved. Moreover, the invention also discloses a transmission signal producing method of the transform domain communication system.
Description
Technical field
The invention belongs to communication technical field, relate in particular to a kind of transform domain communication system and send signal generating method.
Background technology
At transform domain communication system (Transform domain communication system; TDCS) in, in order to make full use of idle frequency spectrum resource, the TDCS system is decomposed into a series of separate spectrum to idle frequency range; In conjunction with the random phase maker; Produce the basic modulation waveform of TDCS system, (Circular Cyclic Shift Keying, CCSK) modulation generates final transmission signal through the cyclic code offset keying.By the way, send signal and have the statistical property that is similar to noise, therefore have lower detection probability (being primarily aimed at unauthorized user).The shortcoming of this scheme is: existing TDCS system utilizes the fast Fourier inversionization, and (Inverse Fast Fourier Transform, the pseudo-random phase sequences that IFFT) the random phase maker is produced becomes the basic modulation waveform of TDCS system.According to central-limit theorem, this waveform has the gaussian statistics characteristic, and (Peak-to-Average Power Ratio, PAPR) problem can reduce the efficient of high power amplifier or introduce nonlinear distortion in real system therefore to have higher peak-to-average power ratio.
Summary of the invention
The objective of the invention is to have proposed a kind of transform domain communication system in order to solve existing TDCS system peak-to-average power ratio problem of higher.
Technical scheme of the present invention is: a kind of transform domain communication system, and the transmitting terminal of said transform domain communication system comprises: frequency spectrum sensing module, frequency spectrum comparison module; Random sequence generator, phase mapping device, pseudo-random phase sequences maker; The inverse Fourier transform module, soft limiting module, Fourier transform module; The CCSK modulation module, wherein
Frequency spectrum sensing module is used for obtaining the spectral characteristic on the different frequency point according to the electromagnetic property of external environment condition;
The frequency spectrum comparison module is used for the sensing results according to frequency spectrum sensing module, and the power spectrum amplitude of different frequency point and the frequency spectrum thresholding that presets are compared, and generates the frequency spectrum sequence;
Random sequence generator is used to generate random bit sequence;
The phase mapping device; Be used for producing corresponding random phase sequence or being used for the output signal of said Fourier transform module phase mapping chart according to said transform domain communication system according to the random bit sequence that random sequence generator generates; And minimum vector distance criterion; Map to the phase place that has minimum range in the phase mapping chart, produce the random phase sequence of new mapping;
The pseudo-random phase sequences maker is used for generating frequency spectrum random phase sequence according to the frequency spectrum sequence of frequency spectrum comparison module generation and the random phase sequence of phase mapping device generation;
The inverse Fourier transform module is used for the frequency spectrum random phase sequence that the pseudo-random phase sequences maker generates is made inverse Fourier transform, the formation base modulation waveform;
The CCSK modulation module is used for basic modulation waveform is modulated;
The soft limiting module; Be used for according to the cycle-index that presets and preset the amplitude thresholding the basic modulation waveform that the inverse Fourier transform module generates is judged; If being less than or equal to, the amplitude peak of basic modulation waveform presets the amplitude thresholding; Then basic modulation waveform is modulated through the CCSK modulation module, directly send then; If surpassing, the part range value of basic modulation waveform presets the amplitude threshold value; Judge then whether cycle-index reaches the cycle-index that presets; When cycle-index more than or equal to the cycle-index that presets; Then basic modulation waveform is modulated through the CCSK modulation module, directly send then, preset amplitude threshold value range value partly for presetting the amplitude threshold value otherwise set to exceed in the basic modulation waveform;
The Fourier transform module is used for the basic modulation waveform behind the soft limiting module amplitude limit is made Fourier transform.
For realizing that the object of the invention has also proposed a kind of transmission signal generating method of transform domain communication system, specifically comprises the steps:
S100. according to the electromagnetic property of external environment condition, detect the spectrum signature of all spectral regions, the spectrum signature of gained is compared with the frequency spectrum thresholding that presets, produce and to be used to the frequency spectrum sequence describing idle frequency spectrum and taken frequency spectrum;
S200. utilize random sequence generator to produce random bit sequence,, produce corresponding random phase sequence then according to the phase mapping chart of said transform domain communication system;
S300. the frequency spectrum sequence and the random phase sequence that step S100 are produced are pursued the element multiplying, obtain frequency spectrum random phase sequence;
S400. the frequency spectrum random phase sequence that step S300 is obtained is carried out inverse Fourier transform, obtains the basic modulation waveform of said transform domain communication system;
S500. according to the cycle-index that presets with preset the amplitude thresholding the basic modulation waveform that step S400 obtains judged; If being less than or equal to, the amplitude peak of basic modulation waveform presets the amplitude thresholding; Then basic modulation waveform is carried out the CCSK modulation, directly send then; If surpassing, the part range value of basic modulation waveform presets the amplitude threshold value; Judge then whether cycle-index reaches the cycle-index that presets; When cycle-index more than or equal to the cycle-index that presets, then basic modulation waveform is carried out CCSK modulation, directly send then; Preset amplitude threshold value range value partly for presetting the amplitude threshold value otherwise set to exceed in the basic modulation waveform, make Fourier transform to setting basic modulation waveform then;
S600. according to the phase mapping chart of said transform domain communication system; And minimum vector distance criterion; Map to the phase place that has minimum range in the phase mapping chart, utilize the output signal after the step S500 Fourier transform to produce the random phase sequence of new mapping, change step S300.
Beneficial effect of the present invention: system and method for the present invention is through setting the thresholding of basic modulation waveform; Handle through signal cycle; The amplitude of basic modulation waveform is controlled within the lower scope; And then the transmission signal that can obtain having the equal power ratio of ebb, reduced high power amplifier to sending the non-linear effects of signal, improved the power amplification efficiency of amplifier.
Description of drawings
Fig. 1 is a TDCS of the present invention system transmitting terminal system block diagram.
Fig. 2 is that TDCS of the present invention system sends the signal generating method schematic flow sheet.
Embodiment
Below in conjunction with accompanying drawing and concrete embodiment the present invention is described in further detail.
Fig. 1 is a TDCS of the present invention system transmitting terminal system block diagram, comprising: frequency spectrum sensing module 11, frequency spectrum comparison module 12; Random sequence generator 13, phase mapping device 14, pseudo-random phase sequences maker 15; Inverse Fourier transform module 16, soft limiting module 17, Fourier transform module 18; CCSK modulation module 19, wherein
Frequency spectrum sensing module 11 is used for obtaining the spectral characteristic on the different frequency point according to the external environment condition electromagnetic property;
Frequency spectrum comparison module 12 is used for the sensing results according to frequency spectrum sensing module, and the power spectrum amplitude of different frequency point and the frequency spectrum thresholding that presets are compared, and generates the frequency spectrum sequence;
Pseudo-random phase sequences maker 15 is used for generating frequency spectrum random phase sequence according to the frequency spectrum sequence of frequency spectrum comparison module 12 generations and the random phase sequence of phase mapping device 14 generations;
Inverse Fourier transform module 16 is used for the frequency spectrum random phase sequence that pseudo-random phase sequences maker 15 generates is made inverse Fourier transform, the formation base modulation waveform;
Fourier transform module 18 is used for the basic modulation waveform behind soft limiting module 17 amplitude limits is made Fourier transform.
Fig. 2 is the transmission signal generating method schematic flow sheet of TDCS of the present invention system, and is specific as follows:
S100. according to the electromagnetic property of external environment condition, detect the spectrum signature of all spectral regions, the spectrum signature of gained is compared with the frequency spectrum thresholding that presets, produce and to be used to the frequency spectrum sequence describing idle frequency spectrum and taken frequency spectrum.This step mainly comprises frequency spectrum perception and Frequency spectrum ratio than two processes, when the power spectrum amplitude greater than the frequency spectrum thresholding that presets, setting this Frequency point numerical value was 0 (representing that this Frequency point takies); When the power spectrum amplitude is less than or equal to the frequency spectrum thresholding that presets, setting this Frequency point numerical value was 1 (representing that this Frequency point is idle).Through above-mentioned frequency spectrum perception and frequency spectrum comparison procedure, can access the frequency spectrum sequence of forming by numerical value 0,1 and be used to describe external environment condition frequency operating position.
S200. utilize random sequence generator to produce random bit sequence,, produce corresponding random phase sequence then according to the phase mapping chart of said transform domain communication system;
S300. the frequency spectrum sequence and the random phase sequence that step S100 are produced are pursued the element multiplying, obtain frequency spectrum random phase sequence.Frequency spectrum random phase sequence is mainly used in and produces the waveform with noise characteristic, has low probability of intercept, and distinguishes different users in the access mode.
S400. the frequency spectrum random phase sequence that step S300 is obtained is carried out inverse Fourier transform, obtains the basic modulation waveform of said transform domain communication system.Because the output result of inverse Fourier transform is the result of frequency spectrum random phase sequence according to the out of phase stack, therefore basic modulation waveform has higher peak-to-average power ratio characteristic usually.
S500. according to the cycle-index that presets with preset the amplitude thresholding the basic modulation waveform that step S400 obtains judged; If being less than or equal to, the amplitude peak of basic modulation waveform presets the amplitude thresholding; Then basic modulation waveform is carried out the CCSK modulation, directly send then; If surpassing, the part range value of basic modulation waveform presets the amplitude threshold value; Judge then whether cycle-index reaches the cycle-index that presets; When cycle-index more than or equal to the cycle-index that presets, then basic modulation waveform is carried out CCSK modulation, directly send then; Preset amplitude threshold value range value partly for presetting the amplitude threshold value otherwise set to exceed in the basic modulation waveform, make Fourier transform to setting basic modulation waveform then.
Can find out, basic modulation waveform is divided into following two kinds of different situations here and handle:
1. preset the amplitude thresholding if basic modulation waveform amplitude peak is less than or equal to, then directly basic modulation waveform is carried out the CCSK modulation, directly send signal then.
2. judge if basic modulation waveform amplitude peak, is then carried out cycle-index greater than presetting the amplitude thresholding, and judge the relation of cycle-index and maximum cycle.When cycle-index more than or equal to the cycle-index that presets, then basic modulation waveform is carried out CCSK modulation, directly send signal then.When cycle-index less than maximum cycle; Then preset amplitude threshold value range value partly for presetting the amplitude threshold value with exceeding in the basic modulation waveform; Make Fourier transform to setting basic modulation waveform then, then export the phase mapping that step S600 carries out a new round to.
S600. according to the phase mapping chart of said transform domain communication system; And minimum vector distance criterion; Map to the phase place that has minimum range in the phase mapping chart, utilize the output signal after the step S500 Fourier transform to produce the random phase sequence of new mapping, change step S300.Here, the phase mapping chart is concrete adopts 2
rThe mapping method of-MPSK modulation.
System and method of the present invention is through setting the thresholding of basic modulation waveform; Handle through signal cycle; The amplitude of basic modulation waveform is controlled within the lower scope; Obtained having the transmission signal of the equal power ratio of ebb, reduced high power amplifier, improved the power amplification efficiency of amplifier sending the non-linear effects of signal.
To those skilled in the art, obviously the invention is not restricted to the details of above-mentioned example embodiment, and under the situation that does not deviate from spirit of the present invention or essential characteristic, can realize the present invention with other concrete form.Therefore; No matter from which point; All should regard embodiment as exemplary; And be nonrestrictive, scope of the present invention is limited accompanying claims rather than above-mentioned explanation, therefore is intended to the implication of the equivalents that drops on claim and all changes in the scope are included in the present invention.Should any Reference numeral in the claim be regarded as limit related claim.A plurality of unit of stating in system's claim in addition, or device also can be realized through software or hardware by a unit or device.
Claims (6)
1. transform domain communication system, the transmitting terminal of said transform domain communication system comprises: frequency spectrum sensing module, frequency spectrum comparison module; Random sequence generator, phase mapping device, pseudo-random phase sequences maker; Inverse Fourier transform module and CCSK modulation module is characterized in that, also comprise soft limiting module and Fourier transform module; Wherein
Frequency spectrum sensing module is used for obtaining the spectral characteristic on the different frequency point according to the electromagnetic property of external environment condition;
The frequency spectrum comparison module is used for the sensing results according to frequency spectrum sensing module, and the power spectrum amplitude of different frequency point and the frequency spectrum thresholding that presets are compared, and generates the frequency spectrum sequence;
Random sequence generator is used to generate random bit sequence;
The phase mapping device; Be used for producing corresponding random phase sequence or being used for the output signal of said Fourier transform module phase mapping chart according to said transform domain communication system according to the random bit sequence that random sequence generator generates; And minimum vector distance criterion; Map to the phase place that has minimum range in the phase mapping chart, produce the random phase sequence of new mapping;
The pseudo-random phase sequences maker is used for generating frequency spectrum random phase sequence according to the frequency spectrum sequence of frequency spectrum comparison module generation and the random phase sequence of phase mapping device generation;
The inverse Fourier transform module is used for the frequency spectrum random phase sequence that the pseudo-random phase sequences maker generates is made inverse Fourier transform, the formation base modulation waveform;
The CCSK modulation module is used for basic modulation waveform is modulated;
The soft limiting module; Be used for according to the cycle-index that presets and preset the amplitude thresholding the basic modulation waveform that the inverse Fourier transform module generates is judged; If being less than or equal to, the amplitude peak of basic modulation waveform presets the amplitude thresholding; Then basic modulation waveform is modulated through the CCSK modulation module, directly send then; If surpassing, the part range value of basic modulation waveform presets the amplitude threshold value; Judge then whether cycle-index reaches the cycle-index that presets; When cycle-index more than or equal to the cycle-index that presets; Then basic modulation waveform is modulated through the CCSK modulation module, directly send then, preset amplitude threshold value range value partly for presetting the amplitude threshold value otherwise set to exceed in the basic modulation waveform;
The Fourier transform module is used for the basic modulation waveform behind the soft limiting module amplitude limit is made Fourier transform.
2. transform domain communication system according to claim 1 is characterized in that, the phase mapping device that described phase mapping device is the tap of r position.
3. transform domain communication system according to claim 1 and 2 is characterized in that, described phase mapping chart is concrete to adopt 2
rThe mapping method of-MPSK modulation.
4. the transmission signal generating method of a transform domain communication system specifically comprises the steps:
S100. according to the electromagnetic property of external environment condition, detect the spectrum signature of all spectral regions, the spectrum signature of gained is compared with the frequency spectrum thresholding that presets, produce and to be used to the frequency spectrum sequence describing idle frequency spectrum and taken frequency spectrum;
S200. utilize random sequence generator to produce random bit sequence,, produce corresponding random phase sequence then according to the phase mapping chart of said transform domain communication system;
S300. the frequency spectrum sequence and the random phase sequence that step S100 are produced are pursued the element multiplying, obtain frequency spectrum random phase sequence;
S400. the frequency spectrum random phase sequence that step S300 is obtained is carried out inverse Fourier transform, obtains the basic modulation waveform of said transform domain communication system;
S500. according to the cycle-index that presets with preset the amplitude thresholding the basic modulation waveform that step S400 obtains judged; If being less than or equal to, the amplitude peak of basic modulation waveform presets the amplitude thresholding; Then basic modulation waveform is carried out the CCSK modulation, directly send then; If surpassing, the part range value of basic modulation waveform presets the amplitude threshold value; Judge then whether cycle-index reaches the cycle-index that presets; When cycle-index more than or equal to the cycle-index that presets, then basic modulation waveform is carried out CCSK modulation, directly send then; Preset amplitude threshold value range value partly for presetting the amplitude threshold value otherwise set to exceed in the basic modulation waveform, make Fourier transform to setting basic modulation waveform then;
S600. according to the phase mapping chart of said transform domain communication system; And minimum vector distance criterion; Map to the phase place that has minimum range in the phase mapping chart, utilize the output signal after the step S500 Fourier transform to produce the random phase sequence of new mapping, change step S300.
5. the transmission signal generating method of transform domain communication system according to claim 4 is characterized in that, the process that said step S100 produces the frequency spectrum sequence is following: when the power spectrum amplitude greater than the frequency spectrum thresholding that presets, setting this Frequency point numerical value is 0; When the power spectrum amplitude is less than or equal to the frequency spectrum thresholding that presets, setting this Frequency point numerical value is 1.
6. according to the transmission signal generating method of claim 4 or 5 described transform domain communication systems, it is characterized in that the described phase mapping chart of step S600 is concrete to adopt 2
rThe mapping method of-MPSK modulation.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102647390A (en) * | 2012-03-21 | 2012-08-22 | 电子科技大学 | Transform domain communication system and realization method thereof |
| CN102932306A (en) * | 2012-09-28 | 2013-02-13 | 达新宇 | Method for improving concealment performance of transform domain communication system (TDCS) signal |
| CN103269323A (en) * | 2013-05-29 | 2013-08-28 | 电子科技大学 | Multi-user transform domain communicating system and method |
| CN106230573A (en) * | 2016-08-31 | 2016-12-14 | 电子科技大学 | A kind of TDCS multiple access based on sequential design accesses improved method |
| CN107317774A (en) * | 2017-06-27 | 2017-11-03 | 电子科技大学 | A kind of CCSK demodulates preprocess method |
| CN113067600A (en) * | 2021-03-16 | 2021-07-02 | 上海磐启微电子有限公司 | Generation method of pseudo-random phase sequence and communication method thereof |
| CN115189993A (en) * | 2022-06-28 | 2022-10-14 | 延安大学 | TDCS basic modulation waveform design method and device and information transmitting and receiving method |
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| 金艳玲: "《哈尔滨工程大学硕士学位论文》", 5 May 2011 * |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102647390A (en) * | 2012-03-21 | 2012-08-22 | 电子科技大学 | Transform domain communication system and realization method thereof |
| CN102647390B (en) * | 2012-03-21 | 2014-10-15 | 电子科技大学 | Transform domain communication system and realization method thereof |
| CN102932306A (en) * | 2012-09-28 | 2013-02-13 | 达新宇 | Method for improving concealment performance of transform domain communication system (TDCS) signal |
| CN102932306B (en) * | 2012-09-28 | 2015-07-22 | 达新宇 | Method for improving concealment performance of transform domain communication system (TDCS) signal |
| CN103269323A (en) * | 2013-05-29 | 2013-08-28 | 电子科技大学 | Multi-user transform domain communicating system and method |
| CN103269323B (en) * | 2013-05-29 | 2016-03-02 | 电子科技大学 | A kind of multi-user's transform domain communication system and method |
| CN106230573A (en) * | 2016-08-31 | 2016-12-14 | 电子科技大学 | A kind of TDCS multiple access based on sequential design accesses improved method |
| CN106230573B (en) * | 2016-08-31 | 2019-04-12 | 电子科技大学 | A kind of TDCS multiple access access improved method based on sequence design |
| CN107317774A (en) * | 2017-06-27 | 2017-11-03 | 电子科技大学 | A kind of CCSK demodulates preprocess method |
| CN107317774B (en) * | 2017-06-27 | 2020-04-17 | 电子科技大学 | CCSK demodulation preprocessing method |
| CN113067600A (en) * | 2021-03-16 | 2021-07-02 | 上海磐启微电子有限公司 | Generation method of pseudo-random phase sequence and communication method thereof |
| CN115189993A (en) * | 2022-06-28 | 2022-10-14 | 延安大学 | TDCS basic modulation waveform design method and device and information transmitting and receiving method |
| CN115189993B (en) * | 2022-06-28 | 2024-01-19 | 延安大学 | TDCS basic modulation waveform design method, device and information transmitting and receiving method |
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