CN103634025B - Frequency spectrum sensing method in a kind of cognitive radio system and system - Google Patents

Abstract

The invention discloses the frequency spectrum sensing method in a kind of cognitive radio system and system, the method comprises: cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum being authorized the characteristic signal of main system arrive the positional information of described cognitive radio system; Described cognitive radio system is according to described positional information determination frequency spectrum perception parameter; Described cognitive radio system utilizes described frequency spectrum perception parameter to perform frequency spectrum perception process.In the embodiment of the present invention, Received signal strength window length and slip associated numbers of times can be reduced, thus reduce the complexity of frequency spectrum perception, and improve the detection perform of frequency spectrum perception.

Description

Frequency spectrum sensing method in a kind of cognitive radio system and system

Technical field

The present invention relates to communication technical field, especially relate to the frequency spectrum sensing method in a kind of cognitive radio system and system.

Background technology

Radio communication frequency spectrum is a kind of natural resources of preciousness, along with the very fast development of wireless communication technology, the poor problem of frequency spectrum resource is day by day serious, in order to alleviate the present situation of frequency spectrum resource anxiety, currently wireless communication spectrum is monitored and studies, find that some frequency range (as TV band) does not use or do not use in most of region in most of time, then there is the situation that multisystem multi-user competes simultaneously in some frequency range, namely the use of frequency spectrum resource exists unbalanced phenomenon.

Propose CR(CognitiveRadio under this background, cognitive radio) concept, the basic thought of cognitive radio is: under not causing the prerequisite of interference to mandate main system, and cognitive radio system can be accessed white spaces carried out dynamic opportunistic by the change of monitoring current radio environment and communicate.Further; when the blank frequency spectrum of cognitive radio system opportunistic insertion authority main system; its prerequisite is that protection authorizes the business of main system not to be subject to the harmful interference of cognitive radio system; this just requires: cognitive radio system accurately can judge the blank frequency spectrum of authorizing main system frequency range; and; when cognitive radio system finds to authorize main system to reappear on the blank frequency spectrum (source working frequency points) of current use, the blank frequency spectrum of current use can be exited in time.

In order to realize said process, cognitive radio system needs to possess frequency spectrum perception ability, so-called frequency spectrum perception refers to: authorizing the signal of main system to judge to authorize main system whether to take target spectrum by detecting on target spectrum, namely judging that target spectrum takies or the free time; And the main method of frequency spectrum perception comprises energy measuring frequency spectrum perception and the frequency spectrum perception based on signal characteristic.

In the mode of energy measuring frequency spectrum perception, directly energy is averaging to the Received signal strength on target spectrum, and by judging whether its energy exceedes a certain thresholding, determines that the whether authorized main system of target spectrum takies; The advantage of energy measuring frequency spectrum perception is that method is simple, and its shortcoming is that the sensitivity of algorithm is lower, and when signal to noise ratio is lower, detection perform is not good.

Based in the frequency spectrum perception mode of signal characteristic, it can comprise matched filtering detection and Autocorrelation Detection further, aforesaid way utilizes the correlation between the correlation between Received signal strength and known array or Received signal strength to detect respectively, and higher sensitivity can be reached, when lower channel ratio, still higher detection perform can be obtained.But, based in the frequency spectrum perception mode of signal characteristic, owing to treating that the mandate main system of perception is not synchronous with between cognitive radio system, in order to ensure the signal characteristic of authorizing main system to be detected, cognitive radio system needs to ensure that characteristic signal drops in receive window, therefore need to receive longer burst, and the relevant summation of slip by symbol is carried out to the burst in receive window, thus cause very high complexity, and the sensitivity of algorithm can be reduced, reduce detection perform.

To authorize main system for DTMB(DigitalTelevisionMultimediaBroadcasting, digital TV multimedia is broadcasted) system illustrates as follows: as shown in Figure 1, for the schematic diagram of DTMB frame structure, suppose that DTMB adopts fixing frame head mode one (frame length N=420), and the frame head of every frame is fixed (supposing to be referred to as PN420 sequence), frame length M=3780.Based on this:

If adopt matched filtering detection algorithm, when cognitive radio system is asynchronous with DTMB system, in order to ensure necessarily to comprise a frame head characteristic signal in Received signal strength, then Received signal strength window length must be more than or equal to (frame head length N+ frame length M), cognitive radio system slides successively relevant the original position using Received signal strength in Received signal strength window, sue for peace relevant to local sequence for these data, in the correlated results slided, select maximum correlated results as detection statistic, detection statistic is compared with a certain thresholding, main system is authorized whether to launch on target spectrum according to comparative result judgement, be shown below:

$r\left(m\right)=\mathrm{abs}\left\{\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x(m+n)s_{\mathrm{PN}}^{*}\left(n\right)\right\},m=\mathrm{0,1,2}...M-1$

$T=\underset{m}{\max }\left[r\left(m\right)\right].$

If adopt Autocorrelation Detection algorithm, when cognitive radio system is asynchronous with DTMB system, for ensureing to comprise two frame head characteristic signals in Received signal strength, Received signal strength window is long is more than or equal to 2 × (frame head length N+ frame length M), cognitive radio system slides successively relevant the original position using Received signal strength in Received signal strength window, Received signal strength auto-correlation after a data and delay frame length is sued for peace, in the auto-correlation result of sliding, select maximum auto-correlation result as detection statistic, detection statistic is compared with thresholding, main system is authorized whether to launch on target spectrum according to comparative result judgement, be shown below:

$r\left(m\right)=\mathrm{abs}\left\{\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x(m+n)x^{*}(m+n+M+N)\right\},m=\mathrm{0,1,2}...M-1$

$T=\underset{m}{\max }\left[r\left(m\right)\right].$

Realizing in process of the present invention, inventor finds at least there is following problem in prior art:

Existing based in the frequency spectrum perception mode of signal characteristic, because cognitive radio system is not synchronous with mandate main system, in order to ensure to receive the characteristic signal of authorizing main system, then cognitive radio system Received signal strength window is much larger than characteristic signal length, and need to slide successively relevant summation in whole Received signal strength window, then ask its maximum to sequence, complexity is very high, reduces detection perform.

Summary of the invention

The embodiment of the present invention provides frequency spectrum sensing method in a kind of cognitive radio system and system, to improve the detection perform of frequency spectrum perception.

In order to achieve the above object, the embodiment of the present invention provides the frequency spectrum sensing method in a kind of cognitive radio system, comprising:

Cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum being authorized the characteristic signal of main system arrive the positional information of described cognitive radio system;

Described cognitive radio system is according to described positional information determination frequency spectrum perception parameter;

Described cognitive radio system utilizes described frequency spectrum perception parameter to perform frequency spectrum perception process.

The embodiment of the present invention provides the system of the frequency spectrum perception in a kind of cognitive radio system, comprising:

Acquisition module, for carrying out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum is authorized the characteristic signal of main system to arrive the positional information of cognitive radio system;

Determination module, for according to described positional information determination frequency spectrum perception parameter;

Processing module, performs frequency spectrum perception process for utilizing described frequency spectrum perception parameter.

Compared with prior art, the embodiment of the present invention at least has the following advantages: in the embodiment of the present invention, can reduce Received signal strength window length and slip associated numbers of times, thus reduce the complexity of frequency spectrum perception, and improve the detection perform of frequency spectrum perception.

Accompanying drawing explanation

In order to be illustrated more clearly in technical scheme of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

Fig. 1 is the schematic diagram of DTMB frame structure in prior art;

Fig. 2 is the schematic diagram of the multi-frame structure of DTMB in prior art;

Fig. 3 is the frequency spectrum sensing method schematic flow sheet in a kind of cognitive radio system provided in the embodiment of the present invention one;

Fig. 4 is the transmitting time diagram of in the embodiment of the present invention one, target spectrum being authorized main system characteristic signal;

Fig. 5 is the structural representation of the perception receiver of a kind of cognitive radio system provided in the embodiment of the present invention two;

Fig. 6 is the structural representation of the frequency spectrum perception system in a kind of cognitive radio system provided in the embodiment of the present invention three.

Embodiment

Inventor is realizing noticing in process of the present invention: authorize main system (as DTMB system) for some, the appearance of its header signal is periodic in time, and may fixedly appear at sometime (which microsecond as nature second); As shown in Figure 2, be the multi-frame structure schematic diagram of DTMB, day frame with a Gregorian calendar consecutive days for the cycle carry out periodicity repeat, it is made up of 1440 framings, time is 24h, is reset, starts new day frame at Beijing time 00:00:00AM or other selected day reference time frame; The time span of a framing is 1min, and comprise 480 superframes, the time span of superframe is defined as 125ms, and 8 superframes are 1s, is convenient to like this and the timing system alignment time; For frame head mode one, every 225 signal frames form a superframe, therefore frame head mode one frame head go out be respectively now in certain nature second in which microsecond on; Therefore header signal periodically occurs in time, and may appear at certain fixed time.Based on above-mentioned discovery, the embodiment of the present invention provides frequency spectrum sensing method in cognitive radio system and system, make cognitive radio system first can obtain time synchronized with mandate main system, and calculate frequency spectrum perception parameter based on time synchronized result, thus obviously can reduce Received signal strength window length and slip associated numbers of times, and significantly reduce the complexity of frequency spectrum perception, improve the detection perform of frequency spectrum perception.

Below in conjunction with the accompanying drawing in the present invention, be clearly and completely described the technical scheme in the present invention, obviously, described embodiment is only a part of embodiment of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.

Embodiment one

The embodiment of the present invention one provides the frequency spectrum sensing method in a kind of cognitive radio system, the method can be applied to the LTE(LongTermEvolution adopting cognitive radio technology, Long Term Evolution) system, TD-SCDMA(TimeDivision-SynchronousCodeDivisionMultipleAcc ess, TD SDMA) system, GSM(GlobalSystemofMobilecommunication, global system for mobile telecommunications) system, WCDMA(WidebandCodeDivisionMultipleAccess, Wideband Code Division Multiple Access (WCDMA)) system, CDMA-2000(CodeDivisionMultipleAccess-2000, Wideband Code Division Multiple Access (WCDMA) 2000) system and WLAN(WirelessLocalAreaNetworks, WLAN (wireless local area network)) etc. mobile communication system.As shown in Figure 3, the method comprises the following steps:

Step 301, cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains target spectrum is authorized the characteristic signal of main system to arrive the positional information of cognitive radio system; Wherein, this positional information includes but not limited to absolute time information, for convenience of description, is described in the embodiment of the present invention for absolute time information.

In the embodiment of the present invention, cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains target spectrum is authorized the characteristic signal of main system to arrive the positional information of cognitive radio system, specifically comprises the following steps:

Steps A, cognitive radio system obtain and treat the prior information of perception target spectrum being authorized main system, the obtain manner of this prior information includes but not limited to: assist by authorizing main system to obtain, by accessing database acquisition, obtained by other cognitive radio systems notice, the acquisition of information prestored by self.

Concrete, cognitive radio system obtains the mode treating the prior information of perception target spectrum being authorized main system, includes but not limited to under type: cognitive radio system authorizes main system notice prior information by receiving, and obtains prior information; Or cognitive radio system stores the database of prior information by access, obtain prior information; Or cognitive radio system, by receiving the prior information of other cognitive radio systems notice, obtains prior information; Or cognitive radio system obtains prior information from the prior information that self prestores.

In the embodiment of the present invention, this prior information includes but not limited to following combination:

The cycle T of the characteristic signal of combination one, mandate main system transmitter _cycle, authorize the reference time cycle T of main system transmitter _refCycle, in cycle reference time, authorize first characteristic signal of main system to arrive the start time position at cognitive radio system geographic location place wherein, reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and reference time cycle T _refCycleit is the cycle T of characteristic signal _cycleintegral multiple.

The cycle T of the characteristic signal of combination two, mandate main system transmitter _cycle, authorize the reference time cycle T of main system transmitter _refCycle, in cycle reference time, authorize the starting location offset T of first characteristic signal of main system _offset; Wherein, reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and reference time cycle T _refCycleit is the cycle T of characteristic signal _cycleintegral multiple.

Certainly, in actual applications, this prior information is not limited to parameter corresponding in combinations thereof, and such as, this prior information can also comprise the length T of characteristic signal in one-period _lengthdeng, for other parameters of prior information, will describe in detail in subsequent process.

As shown in Figure 4, for target spectrum being authorized the transmitting time diagram of main system characteristic signal, for the multi-frame structure of the DTMB shown in Fig. 2, suppose that the transmitted-reference time of DTMB is Beijing time 00:00:00AM, adopt frame head mode one, then every 1s of known DTMB is interior exists 8 superframes, there are 225 signal frames in each superframe, then there is 225 × 8=1800 signal frame in every 1s, and known p interior characteristic signal per second is identical in the original position in per second, the therefore reference time cycle T of desirable mandate main system transmitter _refCycle=1s, the starting location offset T of first characteristic signal in cycle reference time _offset=0, the cycle T of characteristic signal _cycle=frame head length N+ frame length M=555.56 μ s(microsecond), the length T of characteristic signal _length=frame head length N=55.56 μ s(microsecond).

Step B, cognitive radio system utilize on prior information calculating target spectrum authorizes the characteristic signal of main system to arrive the absolute time information of cognitive radio system; This absolute time information is start time position or the start time position scope in absolute moment, i.e. absolute moment position or time location scope.

In the embodiment of the present invention, for the combinations thereof mode of prior information, then cognitive radio system utilizes on prior information calculating target spectrum and authorizes the characteristic signal of main system to arrive the mode of the absolute time information of cognitive radio system, includes but not limited to under type:

Under mode one, which, absolute time information is the start time position in absolute moment, and prior information comprises the cycle T of characteristic signal _cycle, reference time cycle T _refCycle, start time position then within each cycle reference time, cognitive radio system utilizes the start time position in following formulae discovery absolute moment: ${\stackrel{\‾}{T}}_{\mathrm{begin},i}={\hat{T}}_{\mathrm{begin}}+(i-1)\×T_{\mathrm{Cycle}},i=\mathrm{1,2},...P;$ Wherein, for the start time position of cycle reference time internal object frequency spectrum being authorized i-th characteristic signal of main system arrive cognitive radio system, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle.

Under mode two, which, absolute time information is start time position or the start time position scope in absolute moment, and prior information comprises the cycle T of characteristic signal _cycle, reference time cycle T _refCycle, starting location offset T _offset, then, within each cycle reference time, cognitive radio system utilizes the transmitting initial time of following formulae discovery mandate main system characteristic signal: T _{begin, i}=T _offset+ (i-1) × T _cycle, i=1,2 ... P; Wherein, T _{begin, i}for cycle reference time internal object frequency spectrum being authorized the transmitting initial time of i-th characteristic signal of main system, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle; Further, cognitive radio system is according to above-mentioned transmitting initial time T _{begin, i}calculate start time position or the start time position scope of target spectrum being authorized the characteristic signal of main system arrive cognitive radio system geographic location place.

As shown in Figure 4, the reference time cycle T of main system transmitter is authorized _refCycle=1s, the starting location offset T of first characteristic signal in cycle reference time _offset=0, the cycle T of characteristic signal _cycle=555.56 μ s(microseconds), the length T of characteristic signal _length=55.56 μ s(microseconds); Based on this, interior i-th DTMB of each cycle reference time (per second) authorizes the transmitting initial time of the characteristic signal frame head of main system to be specially: T _{begin, i}μ s(is delicate in=(i-1) × 555.56), i=1,2 ... 1800; And the transmitting initial time of the DTMB header signal of employing frame head mode one is (the i-1) × 555.56 μ s in every natural second.

For aforesaid way two, for cognitive radio system according to transmitting initial time T _{begin, i}calculate and target spectrum authorized the characteristic signal of main system arrive the start time position at cognitive radio system geographic location place or the process of start time position scope, can further include:

The geographical location information of authorizing main system transmitter is also comprised in prior information, and geographical location information for determining to authorize the distance at main system transmitter distance cognitive radio system geographic location place to be d time, cognitive radio system utilizes following formulae discovery characteristic signal to arrive the start time position at cognitive radio system geographic location place: wherein, for the start time position of cycle reference time internal object frequency spectrum being authorized i-th characteristic signal of main system arrive cognitive radio system, τ is propagation delay, and c=3 × 10 ⁸m/s, namely c is the light velocity.

The geographical location information of authorizing main system transmitter is also comprised in prior information, and geographical location information for determining to authorize the ultimate range at main system transmitter distance cognitive radio system geographic location place to be no more than Δ d time, cognitive radio system utilizes following formulae discovery characteristic signal to arrive the start time position at cognitive radio system geographic location place: wherein, for the start time position of cycle reference time internal object frequency spectrum being authorized i-th characteristic signal of main system arrive cognitive radio system, τ is propagation delay, and the span of τ is [0, Δ τ], Δ τ is maximum delay spread, and the account form of Δ τ is: c=3 × 10 ⁸m/s, namely c is the light velocity.

Step 302, cognitive radio system determines frequency spectrum perception parameter according to positional information (it includes but not limited to absolute time information); Wherein, this frequency spectrum perception parameter includes but not limited to: the original position of the Received signal strength window of frequency spectrum perception and the length of Received signal strength window, slip associated numbers of times etc.

It should be noted that above-mentioned prior information also can comprise the length T of characteristic signal in one-period _length, and cognitive radio system is according to absolute time information determination frequency spectrum perception parameter, includes but not limited to:

Be start time position at absolute time information (namely authorize the initial time that main system characteristic signal occurs, for absolute time, which of such as each natural second is delicate) time, for the process that frequency spectrum perception detects, then:

For the frequency spectrum perception mode that matched filtering detects, the window's position of cognitive radio system determination Received signal strength window may be the original position of window is the length of Received signal strength window is T _length, slip associated numbers of times L is 1, and in subsequent step, the signal in this receive window is relevant to local sequence; Wherein, for the start time position of cycle reference time internal object frequency spectrum being authorized i-th characteristic signal of main system arrive cognitive radio system;

For the frequency spectrum perception mode of Autocorrelation Detection, cognitive radio system determines that the window's position of 2 Received signal strength windows may be respectively the original position of window is respectively with the length of Received signal strength window is T _length, slip associated numbers of times L is 1, and is correlated with by the signal in these 2 receive windows in subsequent step; Wherein, for the start time position of cycle reference time internal object frequency spectrum being authorized i-th characteristic signal of main system arrive cognitive radio system, for the start time position of cycle reference time internal object frequency spectrum being authorized a jth characteristic signal of main system arrive cognitive radio system.

Be start time position scope [T at absolute time information _{begin, i}, T _{begin, i}+ Δ τ] (namely authorizing the initial time scope that main system characteristic signal occurs) time, for the process that frequency spectrum perception detects, then:

For the frequency spectrum perception mode that matched filtering detects, the window's position of cognitive radio system determination Received signal strength window may be [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ], the original position of window is T _{begin, i}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times L are 1+floor(Δ τ/T _sample), floor(.) represent round downwards; Wherein, T _{begin, i}for cycle reference time internal object frequency spectrum being authorized the transmitting initial time of i-th characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of cognitive radio system, in subsequent step, the signal in this receive window is slided relevant to local sequence, and process correlated series;

For the frequency spectrum perception mode of Autocorrelation Detection, cognitive radio system determines that the window's position of 2 Received signal strength windows may be [T respectively _{begin, i}, T _{begin, i}+ T _length+ Δ τ] and [T _{begin, j}, T _{begin, j}+ T _length+ Δ τ], j ≠ i, the original position of window is respectively T _{begin, i}and T _begin, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times L are 1+floor(Δ τ/T _sample), floor(.) represent round downwards; Wherein, T _{begin, i}for cycle reference time internal object frequency spectrum being authorized the transmitting initial time of i-th characteristic signal of main system, T _{begin, j}for cycle reference time internal object frequency spectrum being authorized the transmitting initial time of a jth characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of cognitive radio system, in subsequent step, the signal in these 2 receive windows is carried out slip and be correlated with, and process correlated series.

Step 303, cognitive radio system utilizes frequency spectrum perception parameter to perform frequency spectrum perception process.

In the embodiment of the present invention, cognitive radio system utilizes frequency spectrum perception parameter to perform frequency spectrum perception process, comprise: cognitive radio system obtains the absolute time of system, utilize the absolute time receive feature signal of frequency spectrum perception parameter and system, and utilize characteristic signal to perform frequency spectrum perception process.

Further, cognitive radio system also needs the absolute time of acquisition system, and in the preferred implementation of the embodiment of the present invention, the mode that cognitive radio system obtains the absolute time of system includes but not limited to: cognitive radio system is by carrying atomic clock determination external time reference, and external time reference is used for the absolute time of certainty annuity; Or cognitive radio system passes through GPS(GlobalPositioningSystem, global positioning system) time service determination external time reference, and external time reference is used for the absolute time of certainty annuity; Or cognitive radio system is by Big Dipper time service determination external time reference, and external time reference is used for the absolute time of certainty annuity; Or, when priori packets of information draws together the external time reference defining method of the absolute time of authorizing main system transmitter, the external time reference defining method of the absolute time of cognitive radio system determination native system is the external time reference defining method of the absolute time of authorizing main system transmitter.

In the embodiment of the present invention, cognitive radio system receives the characteristic signal in absolute time window based on frequency spectrum perception parameter (i.e. Received signal strength window original position, length and slip associated numbers of times etc.), and obtain slip correlated results, and then calculating detection statistic, and detection statistic is compared with a certain decision threshold, finally obtain frequency spectrum perception result, namely target spectrum is authorized to main system and takies or idle.

Detect for matched filtering, suppose that the burst in receive window is [x ₀, x ₁..., x _n-1+L-1], local sequence is [s ₀, s ₁..., s _n-1], wherein for authorizing the number of samples of main system characteristic signal, L is slip associated numbers of times, then a kind of account form of matched filtering detection statistic is as follows:

$r\left(m\right)=\mathrm{abs}\left\{\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x(m+n)s_{\mathrm{PN}}^{*}\left(n\right)\right\},m=\mathrm{0,1,2}...L-1.$

$T=\underset{m}{\max }\left[r\left(m\right)\right]$

For Autocorrelation Detection, suppose that the burst in 2 receive windows is respectively [x ₀, x ₁..., x _n-1+L-1], [y ₀, y ₁..., y _n-1+L-1], wherein for authorizing the number of samples of main system characteristic signal, L is slip associated numbers of times, then a kind of account form of Autocorrelation Detection statistic is as follows:

$r\left(m\right)=\mathrm{abs}\left\{\frac{1}{N}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}x(m+n)y_{\mathrm{PN}}^{*}\left(n\right)\right\},m=\mathrm{0,1,2}...L-1.$

$T=\underset{m}{\max }\left[r\left(m\right)\right]$

It should be noted that, frequency spectrum sensing method in the above-mentioned cognitive radio system that the embodiment of the present invention proposes, also can be used for cognitive radio system and perception is carried out to other cognitive radio systems on target spectrum, repeat no more in the detailed handling process embodiment of the present invention.

Embodiment two

Based on the inventive concept same with said method, in order to support above-mentioned flow process, provide a kind of perception receiver of cognitive radio system in the embodiment of the present invention two, as shown in Figure 5, this perception receiver comprises:

(1) main system prior information acquiring unit is authorized, for obtaining the prior information for the treatment of perception target spectrum to be authorized main system;

(2) main system prior information processing unit is authorized, for the treatment of the prior information of authorizing main system, calculate on target spectrum and authorize the characteristic signal of main system to arrive the absolute time information (i.e. absolute moment position or time location scope equal time information) of cognitive radio system;

(3) frequency spectrum perception parameter calculation unit, absolute time information for utilizing the characteristic signal of authorizing main system to arrive cognitive radio system calculates frequency spectrum perception parameter, and this frequency spectrum perception parameter includes but not limited to frequency spectrum perception Received signal strength window original position, length and slip associated numbers of times;

(4) absolute time clock retrieving unit, for obtaining the absolute time of system;

(5) signal receiving unit, receives one or more characteristic signal for utilizing the absolute time of frequency spectrum perception parameter and system;

(6) frequency spectrum perception performance element, concrete frequency spectrum perception process is performed for utilizing frequency spectrum perception parameter, its specific implementation can be: perform matched filtering detection or Autocorrelation Detection computing based on Received signal strength, obtain slip correlated results, and then calculating detection statistic, and detection statistic is compared with a certain decision threshold, finally obtain frequency spectrum perception result, namely target spectrum is authorized to main system and takies or idle.

Embodiment three

Based on the inventive concept same with said method, provide the frequency spectrum perception system in a kind of cognitive radio system (i.e. cognitive radio system) in the embodiment of the present invention three, as shown in Figure 6, this system comprises:

Acquisition module 11, for carrying out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum is authorized the characteristic signal of main system to arrive the positional information of cognitive radio system;

Determination module 12, for according to described positional information determination frequency spectrum perception parameter;

Processing module 13, performs frequency spectrum perception process for utilizing described frequency spectrum perception parameter.

Described acquisition module 11, treats the prior information of perception target spectrum being authorized main system specifically for obtaining, and utilizes described prior information to calculate on described target spectrum to authorize the characteristic signal of main system to arrive the positional information of described cognitive radio system.

In the embodiment of the present invention, described prior information comprises:

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, in cycle reference time, first characteristic signal of described mandate main system arrives the start time position at described cognitive radio system geographic location place wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple; Or,

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, the starting location offset T of first characteristic signal of described mandate main system in cycle reference time _offset; Wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple.

Described positional information comprises absolute time information, and described absolute time information is the start time position in absolute moment; Described acquisition module 11, is further used for the cycle T comprising characteristic signal in described prior information _cycle, reference time cycle T _refCycle, start time position time, within each cycle reference time, utilize the start time position in absolute moment described in following formulae discovery: ${\stackrel{\‾}{T}}_{\mathrm{begin},i}={\hat{T}}_{\mathrm{begin}}+(i-1)\×T_{\mathrm{Cycle}},i=\mathrm{1,2},...P;$ Wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle.

Described positional information comprises absolute time information, and described absolute time information is start time position or the start time position scope in absolute moment; Described acquisition module 11, is further used for the cycle T comprising characteristic signal in described prior information _cycle, reference time cycle T _refCycle, starting location offset T _offsettime, within each cycle reference time, utilize the transmitting initial time of following formulae discovery characteristic signal: T _{begin, i}=T _offset+ (i-1) × T _cycle, i=1,2 ... P; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle; And, according to described transmitting initial time T _begin, i calculates on described target spectrum and authorizes the characteristic signal of main system to arrive start time position or the start time position scope at described cognitive radio system geographic location place.

Also comprise the geographical location information of authorizing main system transmitter in described prior information, and described geographical location information for determining that the distance at cognitive radio system geographic location place described in described mandate main system transmitter distance is d time; Described acquisition module 11, is further used for utilizing characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: ${\stackrel{\‾}{T}}_{\mathrm{begin},i}=\mathrm{mod}(T_{\mathrm{begin},i}+\mathrm{\τ},T_{\mathrm{refCycle}});$ Wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, τ is propagation delay, and c=3 × 10 ⁸m/s.

Comprise the geographical location information of authorizing main system transmitter in described prior information, and described geographical location information for determining that the ultimate range at cognitive radio system geographic location place described in described mandate main system transmitter distance is no more than Δ d time; Described acquisition module 11, is further used for utilizing characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal, τ is propagation delay, and the span of τ is [0, Δ τ], Δ τ is maximum delay spread, and the account form of Δ τ is: c=3 × 10 ⁸m/s.

In the embodiment of the present invention, described frequency spectrum perception parameter comprises: the original position of the Received signal strength window of frequency spectrum perception and length, slip associated numbers of times.

Described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information; Described determination module 12, specifically for being start time position at described absolute time information time, for the frequency spectrum perception mode that matched filtering detects, determine that the window's position of Received signal strength window is the original position of window is the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, determine that the window's position of 2 Received signal strength windows is respectively with the original position of window is respectively with the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized the jth of a main system characteristic signal.

Described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information; Described determination module 12, specifically for being start time position scope [T at described absolute time information _{begin, i}, T _{begin, i}+ Δ τ] time, for the frequency spectrum perception mode that matched filtering detects, determine that the window's position of Received signal strength window is [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ], the original position of window is T _{begin, i}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor(Δ τ/T _sample), floor(.) represent round downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, determine that the window's position of 2 Received signal strength windows is respectively [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ] and [T _{begin, j}, T _{begin, j}+ T _length+ Δ τ], j ≠ i, the original position of window is respectively T _{begin, i}and T _{begin, j}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor(Δ τ/T _sample), floor(.) represent round downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, T _{begin, j}for target spectrum described in cycle reference time being authorized the transmitting initial time of a jth characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system.

Described processing module 13, specifically for obtaining the absolute time of system, utilizes the absolute time receive feature signal of described frequency spectrum perception parameter and system, utilizes described characteristic signal to perform frequency spectrum perception process.

Described processing module 13, be further used for by carrying atomic clock determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

By global position system GPS time service determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

By Big Dipper time service determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

When described prior information comprises the external time reference defining method of the absolute time of authorizing main system transmitter, determine that the external time reference defining method of the absolute time of native system is the external time reference defining method of the absolute time of described mandate main system transmitter.

Described acquisition module 11, specifically for notifying described prior information by receiving described mandate main system, obtains described prior information; Or, stored the database of prior information by access, obtain described prior information; Or, by receiving the described prior information of other cognitive radio systems notice, obtain described prior information; Or, from the prior information that self prestores, obtain described prior information.

Wherein, the modules of present system can be integrated in one, and also can be separated deployment.Above-mentioned module can merge into a module, also can split into multiple submodule further.

Through the above description of the embodiments, those skilled in the art can be well understood to the mode that the present invention can add required general hardware platform by software and realize, and can certainly pass through hardware, but in a lot of situation, the former is better execution mode.Based on such understanding, technical scheme of the present invention can embody with the form of software product the part that prior art contributes in essence in other words, this computer software product is stored in a storage medium, comprising some instructions in order to make a computer equipment (can be personal computer, server, or the network equipment etc.) perform method described in each embodiment of the present invention.

It will be appreciated by those skilled in the art that accompanying drawing is the schematic diagram of a preferred embodiment, the module in accompanying drawing or flow process might not be that enforcement the present invention is necessary.

It will be appreciated by those skilled in the art that the module in the device in embodiment can carry out being distributed in the device of embodiment according to embodiment description, also can carry out respective change and be arranged in the one or more devices being different from the present embodiment.The module of above-described embodiment can merge into a module, also can split into multiple submodule further.

The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

Be only several specific embodiment of the present invention above, but the present invention is not limited thereto, the changes that any person skilled in the art can think of all should fall into protection scope of the present invention.

Claims (24)

1. the frequency spectrum sensing method in cognitive radio system, is characterized in that, comprising:

Cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum being authorized the characteristic signal of main system arrive the positional information of described cognitive radio system;

Described cognitive radio system is according to described positional information determination frequency spectrum perception parameter;

Described cognitive radio system utilizes described frequency spectrum perception parameter to perform frequency spectrum perception process;

Wherein, described cognitive radio system utilizes described frequency spectrum perception parameter to perform frequency spectrum perception process, comprising:

Described cognitive radio system obtains the absolute time of native system, utilizes the absolute time receive feature signal of described frequency spectrum perception parameter and native system, and utilizes described characteristic signal to perform frequency spectrum perception process.

2. the method for claim 1, it is characterized in that, described cognitive radio system carries out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum being authorized the characteristic signal of main system arrive the positional information of described cognitive radio system, comprising:

Described cognitive radio system obtains and treats the prior information of perception target spectrum being authorized main system;

Described cognitive radio system utilizes described prior information to calculate on described target spectrum to authorize the characteristic signal of main system to arrive the positional information of described cognitive radio system.

3. method as claimed in claim 2, it is characterized in that, described prior information comprises:

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, in cycle reference time, first characteristic signal of described mandate main system arrives the start time position at described cognitive radio system geographic location place wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple; Or,

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, the starting location offset T of first characteristic signal of described mandate main system in cycle reference time _offset; Wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple;

Wherein, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle.

4. method as claimed in claim 3, it is characterized in that, described positional information comprises absolute time information, and described absolute time information is the start time position in absolute moment, described cognitive radio system utilizes described prior information to calculate on described target spectrum and authorizes the characteristic signal of main system to arrive the positional information of described cognitive radio system, comprising:

The cycle T of characteristic signal is comprised in described prior information _cycle, reference time cycle T _refCycle, start time position time, within each cycle reference time, described cognitive radio system utilizes the start time position in absolute moment described in following formulae discovery: wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal.

5. method as claimed in claim 3, it is characterized in that, described positional information comprises absolute time information, and described absolute time information is start time position or the start time position scope in absolute moment, described cognitive radio system utilizes described prior information to calculate on described target spectrum and authorizes the characteristic signal of main system to arrive the positional information of described cognitive radio system, comprising:

The cycle T of characteristic signal is comprised in described prior information _cycle, reference time cycle T _refCycle, starting location offset T _offsettime, within each cycle reference time, described cognitive radio system utilizes the transmitting initial time of following formulae discovery characteristic signal: T _{begin, i}=T _offset+ (i-1) × T _cycle, i=1,2 ... P; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system;

Described cognitive radio system is according to described transmitting initial time T _{begin, i}calculating on described target spectrum authorizes the characteristic signal of main system to arrive start time position or the start time position scope at described cognitive radio system geographic location place.

6. method as claimed in claim 5, it is characterized in that, the geographical location information of authorizing main system transmitter is also comprised in described prior information, and described geographical location information for determining that the distance at cognitive radio system geographic location place described in described mandate main system transmitter distance is d time, described cognitive radio system is according to described transmitting initial time T _{begin, i}calculating on described target spectrum authorizes the characteristic signal of main system to arrive the start time position at described cognitive radio system geographic location place, comprising:

Described cognitive radio system utilizes characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, τ is propagation delay, and c=3 × 10 ⁸m/s.

7. method as claimed in claim 5, it is characterized in that, the geographical location information of authorizing main system transmitter is also comprised in described prior information, and described geographical location information for determining that the ultimate range at cognitive radio system geographic location place described in described mandate main system transmitter distance is no more than Δ d time, described cognitive radio system is according to described transmitting initial time T _{begin, i}calculating on described target spectrum authorizes the characteristic signal of main system to arrive start time position or the start time position scope at described cognitive radio system geographic location place, comprising:

Described cognitive radio system utilizes characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal, τ is propagation delay, and the span of τ is [0, Δ τ], Δ τ is maximum delay spread, and the account form of Δ τ is: c=3 × 10 ⁸m/s.

8. method as claimed in claim 2, it is characterized in that, described frequency spectrum perception parameter comprises: the original position of the Received signal strength window of frequency spectrum perception and length, slip associated numbers of times.

9. method as claimed in claim 8, it is characterized in that, described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information, and described cognitive radio system, according to described positional information determination frequency spectrum perception parameter, comprising:

Be start time position at described absolute time information time, for the frequency spectrum perception mode that matched filtering detects, the window's position of described cognitive radio system determination Received signal strength window is the original position of window is the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, described cognitive radio system determines that the window's position of 2 Received signal strength windows is respectively with the original position of window is respectively with the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized the jth of a main system characteristic signal.

10. method as claimed in claim 8, it is characterized in that, described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information, and described cognitive radio system, according to described positional information determination frequency spectrum perception parameter, comprising:

Be start time position scope [T at described absolute time information _{begin, i}, T _{begin, i}+ Δ τ] time, for the frequency spectrum perception mode that matched filtering detects, the window's position of described cognitive radio system determination Received signal strength window is [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ], the original position of window is T _begin,, _ithe length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor (Δ τ/T _sample), floor (.) expression rounds downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, described cognitive radio system determines that the window's position of 2 Received signal strength windows is respectively [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ] and [T _{begin, j}, T _{begin, j}+ T _length+ Δ τ], j ≠ i, the original position of window is respectively T _{begin, i}and T _{begin, j}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor (Δ τ/T _sample), floor (.) expression rounds downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, T _{begin, j}for target spectrum described in cycle reference time being authorized the transmitting initial time of a jth characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system.

11. methods as claimed in claim 2, is characterized in that, described cognitive radio system obtains the absolute time of native system, comprising:

Described cognitive radio system is by carrying atomic clock determination external time reference, and described external time reference is for determining the absolute time of native system; Or,

Described cognitive radio system is by global position system GPS time service determination external time reference, and described external time reference is for determining the absolute time of native system; Or,

Described cognitive radio system is by Big Dipper time service determination external time reference, and described external time reference is for determining the absolute time of native system; Or,

When described prior information comprises the external time reference defining method of the absolute time of authorizing main system transmitter, the external time reference defining method of the absolute time of described cognitive radio system determination native system is the external time reference defining method of the absolute time of described mandate main system transmitter.

12., as the method in claim 2,3,4,5,6,7,9,10,11 as described in any one, is characterized in that, the acquisition pattern of described prior information, comprising:

Described cognitive radio system notifies described prior information by receiving described mandate main system, obtains described prior information; Or,

Described cognitive radio system stores the database of prior information by access, obtains described prior information; Or,

Described cognitive radio system, by receiving the described prior information of other cognitive radio systems notice, obtains described prior information; Or,

Described cognitive radio system obtains described prior information from the prior information that self prestores.

Frequency spectrum perception system in 13. 1 kinds of cognitive radio systems, is characterized in that, comprising:

Acquisition module, for carrying out synchronous with the mandate main system treated on perception target spectrum, obtains described target spectrum is authorized the characteristic signal of main system to arrive the positional information of cognitive radio system;

Determination module, for according to described positional information determination frequency spectrum perception parameter;

Processing module, performs frequency spectrum perception process for utilizing described frequency spectrum perception parameter;

Wherein, described processing module, specifically for obtaining the absolute time of cognitive radio system, utilizes the absolute time receive feature signal of described frequency spectrum perception parameter and cognitive radio system, and utilizes described characteristic signal to perform frequency spectrum perception process;

Wherein, described cognitive radio system obtains and treats the prior information of perception target spectrum being authorized main system.

14. systems as claimed in claim 13, is characterized in that,

Described acquisition module, treats the prior information of perception target spectrum being authorized main system specifically for obtaining, and utilizes described prior information to calculate on described target spectrum to authorize the characteristic signal of main system to arrive the positional information of described cognitive radio system.

15. systems as claimed in claim 14, it is characterized in that, described prior information comprises:

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, in cycle reference time, first characteristic signal of described mandate main system arrives the start time position at described cognitive radio system geographic location place wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple; Or,

The cycle T of the characteristic signal of described mandate main system transmitter _cycle, the reference time cycle T of described mandate main system transmitter _refCycle, the starting location offset T of first characteristic signal of described mandate main system in cycle reference time _offset; Wherein, described reference time cycle T _refCyclerefer within each cycle reference time, the original position of P characteristic signal is identical in each cycle reference time bias internal amount, and described reference time cycle T _refCycleit is the cycle T of described characteristic signal _cycleintegral multiple;

Wherein, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle.

16. systems as claimed in claim 15, it is characterized in that, described positional information comprises absolute time information, and described absolute time information is the start time position in absolute moment;

Described acquisition module, is further used for the cycle T comprising characteristic signal in described prior information _cycle, reference time cycle T _refCycle, start time position time, within each cycle reference time, utilize the start time position in absolute moment described in following formulae discovery: wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal.

17. systems as claimed in claim 15, it is characterized in that, described positional information comprises absolute time information, and described absolute time information is start time position or the start time position scope in absolute moment;

Described acquisition module, is further used for the cycle T comprising characteristic signal in described prior information _cycle, reference time cycle T _refCycle, starting location offset T _offsettime, within each cycle reference time, utilize the transmitting initial time of following formulae discovery characteristic signal: T _{begin, i}=T _offset+ (i-1) × T _cycle, i=1,2 ... P; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, P is total number of the characteristic signal of the mandate main system comprised in cycle reference time, and P=T _refCycle/ T _cycle; And, according to described transmitting initial time T _{begin, i}calculating on described target spectrum authorizes the characteristic signal of main system to arrive start time position or the start time position scope at described cognitive radio system geographic location place.

18. systems as claimed in claim 17, it is characterized in that, also comprise the geographical location information of authorizing main system transmitter in described prior information, and described geographical location information for determining that the distance at cognitive radio system geographic location place described in described mandate main system transmitter distance is d time;

Described acquisition module, is further used for utilizing characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, τ is propagation delay, and c=3 × 10 ⁸m/s.

19. systems as claimed in claim 17, it is characterized in that, comprise the geographical location information of authorizing main system transmitter in described prior information, and described geographical location information for determining that the ultimate range at cognitive radio system geographic location place described in described mandate main system transmitter distance is no more than Δ d time;

Described acquisition module, is further used for utilizing characteristic signal described in following formulae discovery to arrive the start time position at described cognitive radio system geographic location place: wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal, τ is propagation delay, and the span of τ is [0, Δ τ], Δ τ is maximum delay spread, and the account form of Δ τ is: c=3 × 10 ⁸m/s.

20. systems as claimed in claim 13, it is characterized in that, described frequency spectrum perception parameter comprises: the original position of the Received signal strength window of frequency spectrum perception and length, slip associated numbers of times.

21. systems as claimed in claim 20, it is characterized in that, described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information;

Described determination module, specifically for being start time position at described absolute time information time, for the frequency spectrum perception mode that matched filtering detects, determine that the window's position of Received signal strength window is the original position of window is the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, determine that the window's position of 2 Received signal strength windows is respectively with the original position of window is respectively with the length of Received signal strength window is T _length, slip associated numbers of times is 1; Wherein, for target spectrum described in cycle reference time being authorized i-th of main system characteristic signal arrive the start time position of described cognitive radio system, the start time position of described cognitive radio system is arrived for target spectrum described in cycle reference time being authorized the jth of a main system characteristic signal.

22. systems as claimed in claim 20, it is characterized in that, described prior information also comprises the length T of characteristic signal in one-period _length, described positional information comprises absolute time information;

Described determination module, specifically for being start time position scope [T at described absolute time information _{begin, i}, T _{begin, i}+ Δ τ] time, for the frequency spectrum perception mode that matched filtering detects, determine that the window's position of Received signal strength window is [T _{begin, i}, T _{begin, i}+ T _length+ Δ τ], the original position of window is T _{begin, i}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor (Δ τ/T _sample), floor (.) expression rounds downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system; Or,

For the frequency spectrum perception mode of Autocorrelation Detection, determine that the window's position of 2 Received signal strength windows is respectively [T _{begin, j}, T _{begin, j}+ T _length+ Δ τ], j ≠ i, the original position of window is respectively T _{begin, i}and T _{begin, j}, the length of Received signal strength window is T _length+ Δ τ, slip associated numbers of times is 1+floor (Δ τ/T _sample), floor (.) expression rounds downwards; Wherein, T _{begin, i}for target spectrum described in cycle reference time being authorized the transmitting initial time of i-th characteristic signal of main system, T _{begin, j}for target spectrum described in cycle reference time being authorized the transmitting initial time of a jth characteristic signal of main system, Δ τ is maximum delay spread, T _samplefor the time sampling interval of described cognitive radio system.

23. systems as claimed in claim 13, is characterized in that,

Described processing module, be further used for by carrying atomic clock determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

By global position system GPS time service determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

By Big Dipper time service determination external time reference, and described external time reference is used for the absolute time of certainty annuity; Or,

When described prior information comprises the external time reference defining method of the absolute time of authorizing main system transmitter, determine that the external time reference defining method of the absolute time of native system is the external time reference defining method of the absolute time of described mandate main system transmitter.

24. systems according to any one of claim 15,16,17,18,19,20,22,23, is characterized in that,

Described acquisition module, specifically for notifying described prior information by receiving described mandate main system, obtains described prior information; Or, stored the database of prior information by access, obtain described prior information; Or, by receiving the described prior information of other cognitive radio systems notice, obtain described prior information; Or, from the prior information that self prestores, obtain described prior information.