CN108540416A - Cognitive radio-based C/Ku frequency band NC-OFDM satellite communication method - Google Patents

Cognitive radio-based C/Ku frequency band NC-OFDM satellite communication method Download PDF

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CN108540416A
CN108540416A CN201810236862.2A CN201810236862A CN108540416A CN 108540416 A CN108540416 A CN 108540416A CN 201810236862 A CN201810236862 A CN 201810236862A CN 108540416 A CN108540416 A CN 108540416A
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satellite communication
ofdm
cognitive radio
signal
algorithm
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王勇
王磊
胡以华
郝士琦
樊甫华
焦均均
马涛
朱然刚
骆盛
董世友
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National University of Defense Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0006—Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • 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
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0003—Two-dimensional division
    • H04L5/0005—Time-frequency
    • H04L5/0007—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • H04L5/001—Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT the frequencies being arranged in component carriers

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Radio Relay Systems (AREA)

Abstract

The invention relates to the field of satellite communication, in particular to a method for applying an NC-OFDM communication technology to C/Ku frequency band synchronous satellite communication based on a cognitive radio theory, which comprises the following steps: the method comprises the steps of firstly realizing interaction between an NC-OFDM satellite communication system and a spectrum environment and on-off control of subcarriers by researching a satellite communication spectrum hole sensing method based on cognitive radio, then realizing a system model by researching key technologies such as a carrier allocation scheme and bit power control, and finally realizing optimal design of the system by researching system performance under the coexistence condition with authorized users, and finally realizing coexistence of the NC-OFDM satellite communication system based on cognitive radio and a narrow-band authorization system. The invention realizes the dynamic utilization of the satellite communication spectrum hole, improves the spectrum utilization efficiency and coexists with a narrow-band authorization system through the fusion of the cognitive radio, the NC-OFDM and the satellite communication.

Description

A kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio
Technical field
The present invention relates to satellite communication fields, specifically a kind of that NC-OFDM being communicated skill based on cognition wireless electric theory The method that art is used for C/Ku frequency range synchronous satellite communications.
Background technology
The communication that satellite communication is reliable as a kind of transmission, is not limited by geographical conditions, in recent decades To being widely applied.Traditional fixed channel authorized appropriation pattern is continued to use in the spectrum management of satellite communication at present, by satellite rail Road and the limitation of transponder frequency band, with the raising of portfolio and increasing for number of users, the frequency range of satellite communication is more and more crowded, Frequency spectrum resource is increasingly deficient.But while frequency spectrum resource is in short supply, there is also serious frequency spectrum waste, the frequencies of satellite communication There is a large amount of frequency spectrum cavity-pockets in spectrum.
Federal Communication administration committee (FCC) points out in the report that frequency spectrum policy task groups are write, and is authorizing In the frequency range of distribution, the most of availability of frequency spectrum is only 15% one 85%.This part of report indicates the protrusion of spectrum management Contradiction：Frequency spectrum resource is in short supply, and the availability of frequency spectrum is very low.The reason of causing this phenomenon mainly has two aspects：(1) it authorizes and uses Family does not always occupy entire authorized spectrum band, has band segment to be in idle state；(2) portfolio of authorized user is smaller, compared with Without using authorized spectrum band in the long period.It is above-mentioned analysis shows, wireless communication system is the system of a dynamic change, no Demand with user and business to frequency spectrum changes over time and changes, and static spectrum management pattern obviously can not make frequency spectrum Resource is fully utilized.How to make the distribution of frequency spectrum and access way that there is flexibility and adaptivity, realize frequency spectrum Shared and recycling becomes the hot spot studied at present.
Cognitive radio (Cognitive Radio, CR) and discontinuous orthogonal frequency division multiplexing ultra wide band (Non- Continuous Orthogonal Frequency Division Multiplexing, NC-OFDM) appearance be above-mentioned to ask The solution of topic provides possibility.Cognitive radio is a kind of intelligent wireless communication technology, by perceiving surrounding wireless transmission environment, Transmission information is obtained from environment with the method for " understanding-structure ", and adapts to frequency spectrum ring by changing self transmission parameter The variation in border occupies idle frequency spectrum, in May, 2004 in a manner of " chance access ", and FCC makes an announcement, and allows unauthorized user Certain authorized spectrum bands are used in such a way that chance accesses.
The traditional OFDM technology of NC-OFDM technological improvements, it finds communication using frequency spectrum perception and channel estimation technique Frequency spectrum cavity-pocket in environment only establishes the transmission of data on discontinuous subcarrier corresponding with frequency spectrum cavity-pocket, this just keeps away Exempt to interfere authorized user.The core concept of cognitive radio and NC-OFDM are identical, are all the sides using frequency spectrum share Formula is used in conjunction with frequency spectrum with existing communication system, and to achieve the purpose that improve the availability of frequency spectrum, alleviating ever-increasing business needs The contradiction between increasingly deficient frequency spectrum resource is sought, therefore the NC-OFDM satellite communications based on CR have research valence well Value and development prospect.
Cognition wireless electric theory enables NC-OFDM systems to share frequency spectrum with authorized user, thus can greatly improve The availability of frequency spectrum, but its application is limited only to terrestrial wireless communication at present, this method is by CR, NC-OFDM and satellite communication three In conjunction with, and a kind of NC-OFDM satellite communication systems based on CR are thus designed, satellite communication spectrum utilization efficiency is improved, is delayed The present situation of frequency resource anxiety is solved, and promotes merging for satellite mobile communication system and terrestrial wireless/mobile communications network.
Invention content
Present invention aim to address above-mentioned the deficiencies in the prior art, provide a kind of C/Ku frequency ranges based on cognitive radio NC-OFDM satellite communication methods.
The present invention is achieved by the following technical solutions：
A kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio, include the following steps：Pass through first It studies the satellite communication frequency spectrum cavity-pocket cognitive method based on cognitive radio and realizes NC-OFDM satellite communication systems and spectrum environment Interaction and subcarrier switch control, then pass through study carrier allocation scheme, bit power control key technology realize System model realizes the optimization design of system finally by research with the system performance under authorized user's concurrent conditions, final real Now the NC-OFDM satellite communication systems based on cognitive radio and narrowband authoring system coexist.
Preferably, the satellite communication frequency spectrum cavity-pocket perception based on cognitive radio includes the energy inspection towards transmitting terminal It surveys and the interference temperature towards receiving terminal detects.
Further, the energy measuring towards transmitting terminal includes the following steps：
(1) signal y (t) is filtered out into out-of-band noise by bandpass filter；
(2) square value of signal is calculated by squarer；
(3) gross energy of signal is calculated by integrator；
(4) thresholding is set, the gross energy of signal is made decisions.
Further, the interference temperature detection towards receiving terminal is using the interference inspection based on compressed sensing technology Survey method will replace the perception in different user geographical location with the perception to subscriber signal field strength, sparse in known signal It is compressible in the case of obtain or reconstruction signal restored by restructing algorithm for one group of linear measurement of observation signal Go out sparse signal.
Preferably, the restructing algorithm is to be based on l1The algorithm for reconstructing of norm minimum.
Preferably, the switch control of the NC-OFDM satellite communication systems subcarrier includes the following steps：
(1) ground short distance NC-OFDM systems are used for reference, by C/Ku frequency range NC-OFDM satellite communication system carrier frequencies point Several subcarriers of dispensing use；
(2) according to frequency spectrum cavity-pocket perception as a result, judging whether there is authorization user signal on each subcarrier, if there is awarding It weighs subscriber signal to exist, closes corresponding subcarrier.
Preferably, the carrier allocation scheme, bit power control minimize algorithm, transmission rate most using bit error rate Bigization algorithm or general power minimize algorithm.
Further, it includes greedy algorithm, iterative waterfilling algorithm that the transmission rate, which maximizes algorithm,.
Preferably, the carrier allocation scheme, bit power control use improved greedy algorithm, include the following steps：
(1) switch of each subcarrier is determined according to the result of frequency spectrum perception；
(2) minimum value is set；
(3) power increment needed for all subcarriers one bit of current distribution is calculated, and searches for power increment；
(4) judge whether to meet power constraint, iteration, until reaching the upper limit；
(5) each subcarrier distributing bit and power are given.
The beneficial effects of the present invention are：
(1) by cognitive radio, NC-OFDM and satellite communication triplicity, showing for satellite communication frequency range anxiety will be alleviated Shape solves the problems, such as that current satellite communication spectrum utilization efficiency is low.
(2) cognitive radio technology structure frequency spectrum perception and subcarrier Controlling model are utilized, it is logical to complete NC-OFDM satellites The interaction of letter system and environment will be improved to currently used for the NC-OFDM subcarrier fixed allocation schemes of ground short haul connection Based on the Dynamic Assignment that frequency spectrum cavity-pocket utilizes, the flexible control of NC-OFDM satellite communication system subcarriers is realized.
(3) NC-OFDM satellite communication systems carrier allocation scheme, bit control and power based on cognitive radio are broken through The key technology of control lays the foundation for the NC-OFDM satellite communication system functionizations based on cognitive radio.
Description of the drawings
Fig. 1 is NC-OFDM satellite communications overall study protocol procedures figure of the present invention.
Fig. 2 is energy detector functional block diagram.
Fig. 3 is the ROC curve figure of awgn channel energy detector.
Fig. 4 is interference temperature model figure.
Fig. 5 is that the broader frequency spectrum based on compressed sensing perceives sampler simulation platform structure figure.
Fig. 6 is that 3.1-10.6GHz OFDM UWB frequency bands divide figure.
Specific implementation mode
To be best understood from the present invention, with reference to embodiment and attached drawing, the invention will be further described, following embodiment Only it is that the present invention will be described rather than is limited to it.
As shown in Figure 1, the present invention is realized by the fusion of cognitive radio, NC-OFDM and satellite communication three to satellite The dynamic in communication spectrum cavity utilizes, improves spectrum utilization efficiency and is coexisted with narrowband authoring system.First by studying base The interaction of NC-OFDM satellite communication systems and spectrum environment is realized in the satellite communication frequency spectrum cavity-pocket cognitive method of cognitive radio It is controlled with the switch of subcarrier, then realizes system mould by studying the key technologies such as carrier allocation scheme, bit power control Type realizes that the optimization design of system, final realize are based on finally by research with the system performance under authorized user's concurrent conditions The NC-OFDM satellite communication systems of cognitive radio and coexisting for narrowband authoring system, detailed process is as follows：
One, the satellite communication frequency spectrum cavity-pocket perception based on cognitive radio
Frequency spectrum perception is the basis of satellite communication signals perception, it is the first step of satellite communication signals environment sensing, solution Certainly cognitive user to environmental signal judge with and without the problem of, include mainly energy measuring towards transmitting terminal and towards receiving terminal Interference temperature detection.
1) energy measuring towards transmitting terminal
The design of energy detector is substantially a Hypothesis Testing Problem, and detection performance utilizes detection probability PdAnd void Alarm probability PfIt is weighed.The hypothesis testing model that energy measuring is established under the conditions of considering channel effect is as follows：
H0:Y (t)=n (t)
H1:Y (t)=h*s (t)+n (t) (1)
Wherein y (t) indicates that the reception signal of cognitive user, s (t) indicate that primary user's signal, n (t) indicate additive white gaussian Noise (AWGN), h indicate channel magnitude gain.Null hypothesis H0Expression only exists noise and primary user's signal is not present, standby then assume H1 Indicate that the primary user's signal for having by noise jamming, energy detector principle are as shown in Figure 2.
It is constant in awgn channel lower channel amplitude gain h, then what signal-to-noise ratio γ was also to determine.It can be calculated energy Detection probability P of the detector under awgn channeldWith false-alarm probability PfRespectively：
Wherein T (y) is indicated in H0Under the conditions of energy detector test statistics, λ indicate decision threshold, Γ () indicate not Complete Gamma functions, Qm () indicate m rank broad sense Marcum Q functions.
Fig. 3 is ROC curve of the energy detector under awgn channel, takes signal-to-noise ratio γ=- 5dB, 2dB, 5dB, 8dB, by Fig. 3 is it is found that the detection performance of energy detector improves with the increase of SNR.
The step of energy measuring, is as follows：
(1) signal y (t) is filtered out into out-of-band noise by bandpass filter；
(2) square value of signal is calculated by squarer；
(3) gross energy of signal is calculated by integrator；
(4) thresholding is set, the gross energy of signal is made decisions.
2) the interference temperature detection towards receiving terminal
FCC proposes interference temperature concept, and gives the interference temperature model based on ground short distance cognitive radio, As shown in Figure 4.
Authorized user is produced from fig. 4, it can be seen that interference temperature contains noise floor original in frequency range and CR user Raw jamming power.It is described under authorized user's normal operation on a certain geographical location in the frequency range, and receiver is permitted Perhaps worst radio frequency environment feature, i.e., it provide the interference that authorized user can tolerate and accurately estimate.In authorized spectrum band, one It cuts and causes noise to increase and be allowed to the signal beyond interference temperature thresholding all be prohibited.According to the regulation of FCC, when CR user with When the frequency spectrum share mode insertion authority frequency range of formula coexists, CR user must assure that in the frequency range produced interference it is cumulative not More than preset interference temperature thresholding.
Satellite communication frequency spectrum cavity-pocket detection model based on interference temperature needs to be improved on this basis.For satellite It, can be with the perception to subscriber signal field strength come generation to the perception in different user geographical location for the interference temperature detection of communication It replaces, this provides a new approach to the foundation of the interference temperature detection model based on compressed sensing technology.Using based on pressure The interference temperature detection method of contracting cognition technology, compressed sensing are a kind of sparse or compressible obtain in known signal Or the technology of reconstruction signal, it is directed to one group of linear measurement of observation signal, sparse signal is recovered by restructing algorithm.By It is that original image is subjected to sparse decomposition in transform domain, is ensureing to scheme in image processing field in the initial application of compressed sensing As in the case of reconstruction quality, compressed data as far as possible, to achieve the purpose that reduce storage or transmission data volume.
Assuming that there are one real value to be compressed, having limit for length one-dimensional discrete time signal x, it can be expressed asIn space N × 1 column vector.SpaceBase be(setting it as orthonormal basis), wherein ψiFor the column vector of N × 1, that In arbitrary vector can be indicated with the linear combination of base.By this N number of orthonormal basis constitute a basic matrix Ψ= [ψ1, ψ2..., ψN].Signal x can be expressed as following formula：
Wherein, s=<X, ψi>=ψi TX is the weighting coefficient column vector of N × 1.From formula (3) as can be seen that x and s can table Show signal to be compressed, x is in time domain, frequency domain or spatial domain, and s is in the domains Ψ.If only K larger in column vector s Nonzero value, other are to be similar to 0 fractional value, and K ＜ ＜ N, then signal x is claimed relative to the domains Ψ to be K- sparse either It is compressible.Under desirable channel conditions, signal is by transmission, and receiving end signal is by being y after sample decimation:
Y=Φ x=Φ Ψ s (4)
Wherein y is the vector of M × 1, and the size for the M sample value that its element representation extracts, Φ is the calculation matrix of M × N, Ψ is sparse basis array.When meeting M ＜ ＜ N, compressed data rate is just achieved the purpose that.
The theoretical proof of compressed sensing can choose M by calculation matrix for the signal that K- is sparse from signal x Sample value, receiving terminal can be with prodigious probability reconstruction signals using this M sample value, wherein M >=cKlog (N/K) ＜ ＜ N, c For the constant of very little.Calculation matrix Φ allows for realizing the conversion of the signal x to a length of M of a length of N, but due to M ＜ ＜ N, The equation group established by equation (4) is to owe fixed.However, if x in the domains Ψ is K- sparse (M ＞ ＞ K), and K are non- Position of the zero coefficient in s is known, then the reconstruct probability of signal will become very high.Above-mentioned equation group, which exists, determines solution Sufficient and necessary condition be that matrix Θ=Φ Ψ meet equidistantly limited criterion (RIP), but the complexity of RIP conditions application is very Height, thus Bareaniuk search out a kind of condition of equivalence, i.e., when calculation matrix Φ meets uncorrelated to sparse basis array Ψ, θ Meet RIP conditions.
L is based on when the signal reconstruction algorithm of classics1The algorithm for reconstructing of norm minimum, Solve problems are equivalent to convex optimization Problem can be converted into linear programming problem and solve, and computation complexity is O (N3), when n is large, classic algorithm is answered Miscellaneous degree is very high.
Field is sampled in broader frequency spectrum, due to the limitation of analog device development level and cost so that sensing node is equipped with High-speed DAC generates the Fourier transformation basic matrix of multivalue, and the frequency-domain transform for carrying out sampled signal is unpractical.Therefore, at present Mostly it is to make the PN sequences of two-value to the sampling of signal in the hardware circuit AIC sampled to broader frequency spectrum using compressed sensing For calculation matrix, the transformation by signal from time domain to frequency domain with Fourier transformation basic matrix is cannot achieve, to which letter can not be utilized The sparsity of number frequency domain carries out more accurate restore to signal.Therefore, it studies and designs a sampling with transformation basic matrix Module allows it to carry out the processing of signal in transform domain, makes full use of it in the sparse characteristic of transform domain, in existing hardware Under conditions of equipment, it may be convenient to carry out the acquisition and recovery of time-domain signal, promote further grinding to compressed sensing concept Study carefully and apply, simulation platform structure block diagram is as shown in Figure 5.
Two, suitable for the distribution of the Nc-OFDM carrier frequencies of satellite communication and subcarrier control
NC-OFDM systems itself have the characteristics that carrier Control is flexible, and NC-OFDM satellite communication systems need to only utilize frequency spectrum Cavity, frequency spectrum is no longer Chong Die with authorized user, and carrier allocation scheme can use for reference ground short distance NC-OFDM systems, carries out Improvement is applied to satellite communication.Including following two step：
1) C/Ku frequency ranges NC-OFDM satellite communication system carrier frequencies are distributed
3.1-10.6GHz frequency ranges are mainly directed towards for the research of OFDM technology at present, are illustrated in figure 6 3.1-10.6GHz The frequency band splitting scheme of range OFDM UWB systems.
3.1~10.6GHz frequency ranges are divided into 13 subbands, each subband 528MHz, per height by ground OFDM UWB schemes Band is divided into 128 subcarriers of dispensing and uses, wherein information subcarrier 100, and pilot sub-carrier 12 protects subcarrier 10, Null subcarrier 6.
The band limits of telecommunication satellite is relatively narrow, therefore can not subdivided subband.Such as the frequency of c/Ku band communication satellites Band range only has 500MHz or so, uses for reference ground NC-OFDM schemes, 500MHz bandwidth allocations is used to 122 subcarriers, such as Shown in table 1.
Table 1C/Ku frequency range NC-0FDM satellite communication system subcarriers distribute and OFDM parameters
Parameter Value
Data subcarrier quantity 100
Pilot sub-carrier quantity 12
Protect number of subcarriers 10
Use total number of sub-carriers amount 122
Sub-carrier frequencies interval 4.125MHz
The IFFT/FFT periods 242.42ns
ZP prefixes (37) 70.08ns
OFDM symbol interval 312.5ns
2) C/Ku frequency ranges NC-OFDM satellite communication systems carrier wave subcarrier controls
According to frequency spectrum cavity-pocket perception as a result, judging whether there is authorization user signal on each subcarrier, if there is authorizing Subscriber signal exists, and closes corresponding subcarrier.On the basis of carrier allocation scheme research, control is switched using subcarrier and is calculated Method, make NC-OFDM satellite communication systems using sub-carrier carry out ON/OFF by the way of come avoid authorized user occupancy frequency range, System and the compossibility of authorized user are improved with this.
Three, NC-OFDM satellite communication systems bit and power control
According to Optimum Theory, in the case where the channel status of multicarrier system is certain, if in given bit error rate Limit, two in three parameters of transmission rate and general power, then another there will be optimal solutions, this is also bit and power The theoretical foundation of allocation algorithm.According to the difference of optimizing index, existing algorithm can be divided into 3 classes：The first kind be bit error rate most Smallization algorithm, the general power upper limit and transmission rate (total bit number distributed on each subcarrier in other words) at this moment are constant；Second Class is that transmission rate maximizes algorithm, and the general power upper limit and the bit error rate upper limit at this moment is constant；Third class is general power minimum Change algorithm, transmission rate and the errored bit upper limit at this moment is constant.
One important goal of NC-OFDM satellite communication systems is the high rate data transmission under certain QoS guarantee, so can The power minimization algorithm and transmission rate maximization algorithm for ensureing the bit error rate upper limit will be more meaningful.Since rate maximizes Algorithm can be converted into power minimization algorithm after suitably adjusting, so this project will mainly study rate and maximize calculation Method, emphasis are the optimal algorithms of low computational complexity.
Typical rate maximization algorithm has greedy algorithm, iterative waterfilling algorithm etc., it is contemplated that NC-OFDM satellite communications system The problem of system will face multi-carrier power allocation optimization intends using improved greedy algorithm, first according to frequency spectrum perception As a result it determines the switch of each subcarrier, then power distribution is carried out by the way of increasing bit one by one, first by each subcarrier Bit number be set as minimum value, a minimum ratio of current desired power increment is then searched on all subcarriers repeatedly Spy is just unsatisfactory for total power constraint, computational complexity and sub-carrier number and istributes bit number until being further added by a bit Product is directly proportional.Algorithm steps are：
1) switch of each subcarrier is determined according to the result of frequency spectrum perception；
2) minimum value is set；
3) power increment needed for all subcarriers one bit of current distribution is calculated, and searches for power increment；
4) judge whether to meet power constraint, iteration, until reaching the upper limit；
5) each subcarrier distributing bit and power are given.
At present in terms of the research of frequency spectrum cavity-pocket detection, the detection method towards transmitter is more intuitive, correlative study Comparative maturity, but for satellite communication, due to cannot achieve to the perception of user location, so the detection towards receiving terminal It is relatively difficult.In addition, it is the NC-OFDM based on cognitive radio to solve the compatibility of cognitive system and authoring system between the two The key that can satellite communication system promote and apply.For cognitive system, narrow band signal becomes interference, and this dry It is time-varying to disturb.Therefore the technologies such as the carrier Control of system, bit power control will have the adaptive work(of reply time-varying interference Energy.
Cognitive radio, NC-OFDM and satellite communication triplicity will be alleviated satellite communication frequency range anxiety by the present invention Present situation solves the problems, such as that current satellite communication spectrum utilization efficiency is low.Frequency spectrum perception and son are built using cognitive radio technology Carrier Control model completes the interaction of NC-OFDM satellite communication systems and environment, will be currently used for ground short haul connection NC-OFDM subcarrier fixed allocation schemes are improved to the Dynamic Assignment utilized based on frequency spectrum cavity-pocket, realize NC-OFDM satellites The flexible control of communication system subcarrier.In addition, also breaking through the NC-OFDM satellite communication system carrier waves based on cognitive radio point Key technology with scheme, bit control and power control, it is practical for the NC-OFDM satellite communication systems based on cognitive radio Change is laid a good foundation.
Embodiment described above is only that the preferred embodiment of the present invention is described, not to the model of the present invention It encloses and is defined, under the premise of not departing from design spirit of the present invention, technical side of the those of ordinary skill in the art to the present invention The various modifications and improvement that case is made should all be fallen into the protection domain of claims of the present invention determination.

Claims (9)

1. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio, which is characterized in that including following step Suddenly：First NC-OFDM satellite communications system is realized by studying the satellite communication frequency spectrum cavity-pocket cognitive method based on cognitive radio System is controlled with the interaction of spectrum environment and the switch of subcarrier, is then controlled by research carrier allocation scheme, bit power Key technology realizes system model, realizes the optimization of system with the system performance under authorized user's concurrent conditions finally by research Design, NC-OFDM satellite communication system of the final realization based on cognitive radio coexist with narrowband authoring system.
2. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 1, special Sign is：The satellite communication frequency spectrum cavity-pocket perception based on cognitive radio include energy measuring towards transmitting terminal and towards The interference temperature of receiving terminal detects.
3. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 2, special Sign is that the energy measuring towards transmitting terminal includes the following steps：
(1) signal y (t) is filtered out into out-of-band noise by bandpass filter；
(2) square value of signal is calculated by squarer；
(3) gross energy of signal is calculated by integrator；
(4) thresholding is set, the gross energy of signal is made decisions.
4. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 1, special Sign is：The interference temperature detection towards receiving terminal is to use the interference detection method based on compressed sensing technology, will be right The perception in different user geographical location is replaced with the perception to subscriber signal field strength, known signal is sparse or compressible feelings It is obtained under condition or reconstruction signal recovers sparse signal for one group of linear measurement of observation signal by restructing algorithm.
5. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 4, special Sign is：The restructing algorithm is to be based on l1The algorithm for reconstructing of norm minimum.
6. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 1, special Sign is that the switch control of the NC-OFDM satellite communication systems subcarrier includes the following steps：
(1) ground short distance NC-OFDM systems are used for reference, C/Ku frequency range NC-OFDM satellite communication system carrier frequencies are distributed to Several subcarriers use；
(2) according to frequency spectrum cavity-pocket perception as a result, judging whether there is authorization user signal on each subcarrier, if there is authorizing use Family signal exists, and closes corresponding subcarrier.
7. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 1, special Sign is：The carrier allocation scheme, bit power control minimize algorithm using bit error rate, transmission rate maximizes algorithm Or general power minimizes algorithm.
8. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 7, special Sign is：It includes greedy algorithm, iterative waterfilling algorithm that the transmission rate, which maximizes algorithm,.
9. a kind of C/Ku frequency range NC-OFDM satellite communication methods based on cognitive radio according to claim 1, special Sign is that the carrier allocation scheme and bit power control use improved greedy algorithm, include the following steps：
(1) switch of each subcarrier is determined according to the result of frequency spectrum perception；
(2) minimum value is set；
(3) power increment needed for all subcarriers one bit of current distribution is calculated, and searches for power increment；
(4) judge whether to meet power constraint, iteration, until reaching the upper limit；
(5) each subcarrier distributing bit and power are given.
CN201810236862.2A 2018-03-21 2018-03-21 Cognitive radio-based C/Ku frequency band NC-OFDM satellite communication method Pending CN108540416A (en)

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CN110312262A (en) * 2019-06-28 2019-10-08 中国人民解放军国防科技大学 Interference analysis method of NC-OFDM satellite communication system to authorization system
CN110380798A (en) * 2019-07-24 2019-10-25 深圳大学 The parameter optimization method of non-orthogonal multiple Verification System based on shared authenticating tag
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CN110312262A (en) * 2019-06-28 2019-10-08 中国人民解放军国防科技大学 Interference analysis method of NC-OFDM satellite communication system to authorization system
CN110380798A (en) * 2019-07-24 2019-10-25 深圳大学 The parameter optimization method of non-orthogonal multiple Verification System based on shared authenticating tag
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CN112838890A (en) * 2021-02-07 2021-05-25 航天科工空间工程发展有限公司 Satellite communication system with cooperative spectrum sensing and communication
CN112996051A (en) * 2021-04-27 2021-06-18 融智通科技（北京）股份有限公司 Microwave backhaul method, switch and computer readable storage medium

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