CN102221694B - Measuring frequency selection method based on prime sequence in radio interference positioning - Google Patents

Abstract

The invention relates to a measuring frequency selection method based on a prime sequence in radio interference positioning. The invention provides a construction method which can avoid a frequency interval formed by an integer ambiguity solution, namely a prime-based frequency interval construction method; and meanwhile, an optimal sequence arrangement of the frequency interval is designed, wherein a primary interference measurement comprises three anchor nodes in known positions and a node to be positioned, the two anchor nodes are set as transmitting nodes, the other anchor node and the node to be positioned are set as receiving nodes; the method comprises the steps of a frequency calibration of the transmitting nodes, a design of the interference measuring frequency interval, a design of the interference measuring frequency interval optimizing arrangement, transmitting and receiving node time synchronization, an interference enveloping phase difference estimation, interference distance estimation and node position estimation and the like. By using the method provided by the invention, the problem that the laying range is limited because of the integer ambiguity in the equal frequency interval interferometry ranging system can be solved. The ranging precision of the method provided by the invention is higher than that of the existing equal frequency interval interferometry ranging method.

Description

In the radio interference location based on the survey frequency system of selection of prime number sequence

Technical field

The present invention relates to the ranging technology in the radio interference location, particularly in the radio interference range finding based on the survey frequency system of selection of prime number sequence.

Background technology

Location in the wireless network comprises two big classes: based on the method for range finding and the method for non-range finding.

Non-distance-finding method utilizes internodal link information location, do not need extra hardware device, but general precision is not high.Come measuring position known node and internodal distance to be positioned, range difference or directional information based on distance-finding method by amplitude, phase place or the frequency of measuring-signal.Measuring-signal comprises sound wave, ultrasound wave, infrared and radio signal.Distance-finding method comprises range finding time of arrival (TOA), difference range finding time of arrival (TDOA), angle of arrival range finding (AOA), receives signal energy range finding (RSS) and radio interference range finding (RIPS).On finding range, sound wave, ultrasound wave or infrared signal finding range are at several meters to tens meters, and the radio signal finding range is then from several kilometers to several ten thousand kilometers.Except receiving the signal energy range finding, higher based on the general precision of localization method of range finding, but need expensive hardware.

In the wireless network location, bearing accuracy, orientation range and cost are to estimate good and bad three major criterions of positioning system.Expensive hardware cost has limited range finding class localization method and has laid application in the network on a large scale.The radio interference ranging technology occurs, and has solved the contradiction between bearing accuracy and node cost.

In the radio interference positioning system (Radio Interferometric Positioning System RIPS), transmission frequency is close simultaneously for two source node A, B, is respectively f ₁, f ₂The high_frequency sine wave signal, two sinusoidal signals produce interference at receiving node C, D.C, D node are with high frequency interference signal process of frequency multiplication, and low-pass filtering is taken out the low frequency envelope of interference signal then, calculate envelope phase

Two receiving node envelope phases poor

Corresponding quaternary is apart from combination d _ABCD=d _AD-d _BD+ d _BC-d _AC, and claim d _ABCDInterference distance for four-tuple ABCD correspondence.Wherein, d _XY(X, Y ∈ A, and B, C, the D}) distance of expression nodes X, Y, as shown in Figure 1.

In interfering positioning system, at first utilize and measure

Estimate d _ABCD, and then estimate the position of node to be positioned according to the interference distance of different nodes combination.

The radio interference location technology has the following advantages:

1. require low synchronously to clock: transmitting terminal does not need synchronously; And receiving end only needs the synchronization accuracy of microsecond level, can finish the synchronous of node by the time synchronization protocol of network.

2. hardware cost is low: because receiving end only needs hundreds of hertz low frequency envelope signal is sampled and calculated phase place, A/D sampling device and corresponding hardware circuit are required low, hardware cost is low.

3. bearing accuracy height: the bearing accuracy of existing radio interference positioning system can reach centimetre-sized.

4. finding range is controlled: finding range is subjected to frequency interval control, can reach hundreds of rice.

Therefore, compare with existing other range finding class localization methods, the radio interference location technology has great technical advantage.

But the radio interference location technology adopts interfeerometry ranging, and interfeerometry ranging belongs to the category of phase ranging, and integral circumference ambiguity solution (being the whole number of wavelengths of the unknown that comprises in the estimated value of nodal distance) is its essential problem that faces.For this reason, can only limit the distance between the node by the laying scope (finding range) that limits positioning system, make it less than the cycle of integral circumference ambiguity solution, thereby get rid of singular solution.Existing interference positioning system generally adopts the method for uniformly-spaced choosing survey frequency, and in other condition one regularly, integral circumference ambiguity solution cycle and the frequency interval of this method are inversely proportional to.On the other hand, frequency interval reduces, and range error will increase rapidly, as shown in Figure 3.This has just caused producing between distance accuracy and the finding range implacable contradiction.Therefore, the drawback of this method is: in the frequency of measuring and bandwidth one timing, increasing distance accuracy inevitable be cost to sacrifice finding range; Vice versa.

Because the existence of integral circumference ambiguity problem, distance accuracy and finding range are difficult to take into account also and can't solve in the existing uniformly-spaced interfeerometry ranging method.

Summary of the invention

Purpose of the present invention just is to overcome above-mentioned defective, and the survey frequency system of selection based on the prime number sequence is provided in a kind of radio interference location.

Technical scheme of the present invention is:

Based on the survey frequency system of selection of prime number sequence, its major technique step is in the radio interference location:

(1) transmit and receive the setting of node: an interferometry comprises anchor node and node to be positioned of three location awares, and two anchor nodes are set to transmitting node, and another anchor node and node to be positioned are set to receiving node;

(2) transmitting node frequency calibration: the frequency to two transmitting nodes is calibrated, and eliminates their nominal transmission frequency deviation;

(3) interferometry frequency interval design: utilize the interval between all adjacent survey frequencies of prime number sequence structure, namely construct Δ f _i, Δ f _i=f _I+1-f _i

(4) the interferometry frequency interval optimizes the arrangement of design: utilize optimization method to determine survey frequency ordering at interval; According to the optimal sequencing of frequency interval, determine final one group of N survey frequency f _i, i=1 ... N;

(5) emission, receiving node time synchronized: utilize clock synchronization protocol receiving node synchronously, make it begin to receive operation in the identical moment;

(6) interfere the envelope phase difference to be estimated: two transmitting nodes are respectively in a pair of frequency f _iAnd f _i+ f _LThe sine wave that last transmission frequency is close, f _LBe fixing low frequency signal, two sine wave signals form interference signal at two receiving nodes; Calculate the phase place of two receiving node place interference signal envelopes respectively, obtain the poor of two envelope phases

(7) interference distance is estimated: respectively many to frequency on repeating step (2) and (6), measure a plurality of

Unite and find the solution interference distance d _ABCD, single d _ABCDThe track of determined node to be positioned is a hyperbolic curve;

(8) node location is estimated: use the combination of different anchor nodes and node to be positioned, obtain different d _ABCDAnd hyperbolic curve, many hyperbolic curve intersection points are node location to be positioned.

The present invention is absorbed in the wherein design of survey frequency based on the radio interference ranging technology, is intended to solve the contradiction between the distance accuracy and finding range in the existing radio interference ranging technology.Count under the same terms in available total bandwidth and the survey frequency of measurement, the present invention has provided a kind of didactic Frequency Design method, constructed the optimization frequency interval based on prime number, obtain the optimal alignment order of frequency interval simultaneously, provided a concrete and detailed example of choosing survey frequency with prime number at last.

The concrete difference of the present invention and previous methods is:

1. the present invention has solved the finding range and the distance accuracy that wherein exist and has contradicted problem based on radio interference range measurement system RIPS.

2. the phase ranging method difference is in the present invention and the GPS positioning system: (a) GPS utilizes the phase place of carrier frequency rather than the phase place of interference signal to find range, the integral circumference ambiguity problem that solves in the phase ranging need be utilized extraneous information, the rough estimate that provides as pseudo-random code ranging; (b) gps system is only launched distance measuring signal in fixing frequency, does not relate to the problem of choosing of survey frequency.

3. the phase ranging method difference is in the present invention and the continuous wave radar, can directly measure the phase information on the single carrier frequency in the radio interference range measurement system, and continuous wave radar is measured in twos phase differential on the carrier frequency, when the survey frequency number is identical, because phase ranging method can not obtain the phase information on the single carrier frequency in the radar, the information that comprises is less than the RIPS method, so distance accuracy will be lower than the RIPS method; Each frequency of design tackles the integral circumference ambiguity problem with interval between reference frequency in the continuous wave radar, and the present invention designs adjacent survey frequency interval; After reference frequency is fixing, each survey frequency is determined in the continuous wave radar, and the present invention is after frequency interval is determined, survey frequency still has infinite kind combination, utilize this characteristic just, the present invention has designed survey frequency optimum combination at interval when the structure frequency interval is used for eliminating integral circumference ambiguity.

Be that characteristics of the present invention can be summarized as: the present invention is applied to the RIPS range measurement system, under the total bandwidth confined condition, utilize the prime number sequence, construct adjacent survey frequency at interval, make it to take full advantage of the measurement bandwidth, optimize the frequency interval ordering simultaneously, finally reach and eliminate the integral circumference ambiguity solution and improve the distance accuracy double goal.

The present invention uses emulation to disclose the performance of institute's inventive method.The result shows that the present invention produces a desired effect, do not increase under the prerequisite of hardware cost, has solved the difficult problem of distance accuracy and scope contradiction in the interfeerometry ranging, realizes simple with stylish interfeerometry ranging method.At identical available measurement width with measure under the condition of frequency, when the finding range of the inventive method is expanded greatly, distance accuracy even be higher than uniformly-spaced method.Being worth mentioning is, uniformly-spaced distance-finding method itself just has higher distance accuracy, so method also is a kind of precision distance measurement method simultaneously among the present invention.

Description of drawings

Fig. 1---radio interference location transmitting-receiving node arrangement plan in the prior art.

Fig. 2---radio interference positioning principle block diagram among the present invention.

Fig. 3---uniformly-spaced range finding in the prior art, measuring frequency number and frequency influences synoptic diagram to distance accuracy at interval.

Fig. 4---the long synoptic diagram of the complete cycle of different distance-finding method integral circumference ambiguities among the present invention wherein, (a) is q_range=200m, N=41, uniformly-spaced method Δ f=0.1MHz; (b) be q_range=200m, N=41, uniformly-spaced method Δ f=0.5MHz; (c) be q_range=200m, N=41 is based on the prime number frequency selecting method;

Fig. 5---among the present invention based on the enforcement block diagram of prime number optimization method.

Fig. 6---offset search function primary and secondary peak concerns synoptic diagram among the present invention.

Fig. 7---among the present invention during different frequent points uniformly-spaced with based on prime number Optimization Design distance accuracy synoptic diagram relatively.

Fig. 8---among the present invention during different bandwidth uniformly-spaced with based on prime number Optimization Design distance accuracy synoptic diagram relatively.

Embodiment:

To divide several sections to elaborate the present invention below.Comprise the specific implementation step of system of selection of the present invention and the performance of new method, the performance of new method is mainly weighed with distance accuracy and finding range.New method has solved between radio interference distance accuracy and the scope and has had contradiction.

Below further set forth major technique step of the present invention.

As shown in Figure 2:

Step (1). transmit and receive the setting of node

An interferometry comprises four nodes in the radio interference location, i.e. two transmitting node A, B and two receiving node C, D, the interference distance d that measures _ABCDBe quaternary apart from combination, i.e. d _ABCD=d _AD-d _BD+ d _BC-d _AC

For the ease of location compute, an interferometry comprises three anchor nodes and a node to be positioned, and wherein two anchor nodes are set to transmitting node, and another anchor point and node to be positioned are set to receiving node; The corresponding hyperbolic curve of such interference distance uses many hyperbolic curves can determine the position of node to be positioned.See formula (9).In addition, consider GDOP (the Geometric Dilution of Precision) problem in the location, two transmitting nodes distance can not be too near, when selecting the anchor node of measurement in addition, avoids anchor node and node to be positioned point-blank as far as possible.

Step (2). the transmitting node frequency calibration

When two transmitting nodes sine wave signal that transmission frequency is close simultaneously, receiving end forms interference signal, and the beat frequency of formed interference signal poor for the frequency of interfering source signal.When calculating the phase place of interference signal envelope, it is sampled to signal intensity after by low-pass filter.Producing good interference signal key is to interfere source node can accurately launch the sine wave of assigned frequency.

If the degree of stability of the crystal oscillator of transmitting node is not high enough, make the actual frequency and the assigned frequency that transmit not be inconsistent, can adopt the method for frequency calibration this moment.In the interfeerometry ranging, the purpose of frequency calibration makes that the difference on the frequency of two transmitting nodes is accurate controlled value.

The present invention is example with low-cost node M ica2 sensor node, and the temperature compensating crystal oscillator of the CC1000 chip internal that Mica2 adopts is subject to Effect of Environmental and produces frequency shift (FS).For this reason, cross the Cheng Qian in interferometry and must carry out the difference that frequency adjustment is reduced interference source node frequency.Interfere the frequency computation part formula of source signal to be:

f＝430.1+0.526×channel+65·10 ^-6×tuning (MHz) (1)

In the formula: channel---the frequency range sequence number of current measurement;

Tuning---the frequency adjusted value on the corresponding band.

Herein, 430.1MHz is the reference frequency in CC1000 radio station, and 0.526MHz is the interval of adjacent measurement frequency range, and 65Hz is the base unit that frequency is adjusted.Be in course of adjustment, interfere the frequency of source node to remain unchanged for one, constantly change the frequency adjusted value of another one source node, receiving node is measured the frequency of interference signal envelope, when the frequency of envelope approaches zero, receiving node is selected corresponding optimum calibration values and is reported to transmitting node, and the calibration value that latter's foundation receives is adjusted the setting of self frequency register, and the frequency calibration process finishes.

Step (3). the design of interferometry frequency interval

The invention provides a kind of optimization frequency interval system of selection based on prime number.Optimize frequency interval system of selection emphasis and consider the selection at survey frequency interval rather than the design of survey frequency itself.Because equifrequent is to produce integral circumference ambiguity at interval, and the girth of complete cycle is directly determined every kind of corresponding complete cycle of frequency interval by frequency interval.Can take a hint directly perceived from this, if use a plurality of different frequency intervals, in the offset search function, the complete cycle of every kind of frequency interval correspondence is long not to overlap (except correct interference distance q_range) in same position as far as possible, namely except on the true interference distance, the locational peak value of other integral circumference ambiguities Overlay can not occur.The present invention will provide a kind of method to avoid the stack of non-actual position upward peak as far as possible.

For convenience, at first do as giving a definition.The set that all adjacent measurement frequencies are constituted at interval is designated as Δ F, (each element Δ f wherein _i=f _I+1-f _i) define the long S set q of complete cycle of an integral circumference ambiguity simultaneously, each element S q (i) is positive integer in the set, and and set Δ F in element corresponding one by one, Sq (i)=c/ Δ f _i

Element designs by following principle among the S set q:

To any i, j＜N, if i ≠ j is S _q(i) m=S _q(j) n, then requirement

m＝k·S _q(j)，n＝k·S _q(i) (2)

Wherein k is any positive integer, and N is the number of element in the set.

By the long S set q of the complete cycle of above-mentioned criterion design, any p element S q (1) wherein, ... the long fuzzy solution of the different complete cycles of the corresponding p kind of Sq (p), every kind of fuzzy solution has infinite a plurality of, but this p kind fuzzy solution is independent separately, only privileged site stack form with true interference distance on analogous peak value, these privileged sites are

Illustrate, if the frequency interval sequence is Δ F={300/101MHz, 300/103MHz, 300/107MHz}, i.e. Sq={101m, 103m, 107m}.In uniformly-spaced finding range, these three kinds of frequency intervals respectively form as upper/lower positions with actual position on the fuzzy peak value k101 that intends of comparable size, k103, k107, k are arbitrary integer. and fuzzy peak value only appears at the k101103107 place in optimizing the frequency interval system of selection.

Can prove, suppose that the long S set q of complete cycle is made of Sq={m prime number ₁, m ₂... m _N| m _iBe prime number, i=1...N}, the finding range that does not have fuzzy solution so is

The present invention utilizes prime number to constitute S set q, can verify that obviously the prime number set satisfies the condition of formula (2).

Frequency interval system of selection based on prime number is described below (Fig. 5):

Measuring under frequency N and the bandwidth B specified criteria, produce K prime number set { Pr (k) that arranges according to ascending order, k=1,2...K, K＞＞N}, and from K set, carry out L and doubly extract, namely from set, take out an element every L element, to increase the difference between prime number, obtain K/L prime number as the long candidate collection Pr of complete cycle.Wherein, integer K is much larger than the measurement frequency number of interfeerometry ranging, integer L value L=2 among the present invention.

Select N+1 continuous prime number to constitute prime number subclass Sq from the long set of complete cycle Pr, this prime number set is Δ f with the corresponding relation of frequency interval _j=c/Sq (j), Sq (j)=Pr (i+j-1), c is the light velocity.Determine this section prime number reference position i by way of search, Sq={Pr (i), Pr (i+1) ... Pr (i+N-1), Pr (i+N) }, make the top n prime pair is answered among the Sq frequency interval sum greater than bandwidth B, namely

$\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δf}}_j=\underset{j=i}{\overset{i+N-1}{\mathrm{\Σ}}}(c/P_r\left(j\right))>B---\left(3\right)$

Simultaneously, the frequency interval sum that a back N prime pair is answered is less than bandwidth B, and this will make that measuring frequency takies wide as far as possible bandwidth, and bandwidth is conducive to the distance accuracy raising, sees Fig. 3, Fig. 8.

Namely

$\underset{j=2}{\overset{N+1}{\mathrm{\Σ}}}{\mathrm{\Δf}}_j=\underset{j=i+1}{\overset{i+N}{\mathrm{\Σ}}}(c/P_r\left(j\right))\≤B---\left(4\right)$

Δ F={ Δ f _j| j=2...N+1} is the frequency interval set of final structure.

Step (4). the interferometry frequency interval optimizes the arrangement of design

Emulation shows, near departure function main peak (true interference distance place) and secondary peak (the interior secondary peak of the several wavelength coverages main peak especially, this is the main source of interfeerometry ranging error) difference is more big, secondary peak is mistaken for main peak and causes the probability of range error more little, the antinoise effect is more good, as Fig. 6.

In order to increase main peak and the first secondary peak difference as far as possible, the thought that optimizes the arrangement of is as follows:

The frequency interval sequence is resequenced, its element is had increase progressively the character of afterwards successively decreasing earlier, thereby make survey frequency densely distributed at the frequency band two ends, distribute sparse at band center, make the offset search function that bigger secondary peak be arranged, namely the difference of main peak secondary peak is more obvious.When survey frequency N is odd number, N frequency interval at first by arranging from big to small, obtained gathering Δ F={ Δ f ₁, Δ f ₂, Δ f ₃... Δ f _N, Δ f ₁＞Δ f ₂＞...＞Δ f _N, rearrange element in the set then, newly gathered Δ F _Op1={ Δ f _N, Δ f _N-2, Δ f _N-4... Δ f ₃, Δ f ₁, Δ f ₂, Δ f ₄... Δ f _N-3, Δ f _N-1.When N is even number, newly gather Δ F _Opt={ Δ f _N-1, Δ f _N-3, Δ f _N-5... Δ f ₃, Δ f ₁, Δ f ₂, Δ f ₄... Δ f _N-2, Δ f _N.

Whole frequency selection course such as Fig. 5.

According to mentioned above principle, a concrete example is: supposition measuring-signal bandwidth B=40.5MHz, frequency band range 400MHz～440.5MHz measures frequency N=41.Frequency interval designs as follows

At first the prime number of productive set size K=200 is gathered Pr:

Pr＝{2，3，5，7，11，13，17，19，23，29，31，37，41，43，47，53，59，61，67，71，73，79，83，89，97，101，103，107，109，113，127，131，137，139，149，151，157，163，167，173，179，181，191，193，197，199，211，223，227，229，233，239，241，251，257，263，269，271，277，281，283，293，307，311，313，317，331，337，347，349，353，359，367，373，379，383，389，397，401，409，419，421，431，433，439，443，449，457，461，463，467，479，487，491，499，503，509，521，523，541，547，557，563，569，571，577，587，593，599，601，607，613，617，619，631，641，643，647，653，659，661，673，677，683，691，701，709，719，727，733，739，743，751，757，761，769，773，787，797，809，811，821，823，827，829，839，853，857，859，863，877，881，883，887，907，911，919，929，937，941，947，953，967，971，977，983，991，997，1009，1013，1019，1021，1031，1033，1039，1049，1051，1061，1063，1069，1087，1091，1093，1097，1103，1109，1117，1123，1129，1151，1153，1163，1171，1181，1187，1193，1201，1213，1217，1223}

From prime number set Pr set, carry out 2 times of extractions, increase the difference of prime number, obtain new prime number set

Pr＝{2，5，11，17，23，31，41，47，59，67，73，83，97，103，109，127，137，149，157，167，179，191，197，211，227，233，241，257，269，277，283，307，313，331，347，353，367，379，389，401，419，431，439，449，461，467，487，499，509，523，547，563，571，587，599，607，617，631，643，653，661，677，691，709，727，739，751，761，773，797，811，823，829，853，859，877，883，907，919，937，947，967，977，991，1009，1019，1031，1039，1051，1063，1087，1093，1103，1117，1129，1153，1171，1187，1201，1217}

Select wherein continuation subset, Pr (17) ... Pr (57) constitutes Sq according to formula (4)

Sq={137,149,157,167,179,191,197,211,227,233,241,257,269,277,283,307,313,331,347,353,367,379,389,401,419,431,439,449,461,467,487,499,509,523,547,563,571,587,599,607,617} (unit: rice)

At this moment, the finding range of no fuzzy solution is

(unit: rice).For a practical position system, can be considered as not having the finding range infinity of fuzzy solution.

Next step obtains putting in order of 41 elements among the Sq according to optimization method directly perceived

Index_opt＝[41，39，37，35，33，31，29，27，25，23，21，19，17，15，13，11，9，7，5，3，1，2，4，6，8，10，12，14，16，18，20，22，24，26，28，30，32，34，36，38，40]；

The Sq that is optimized according to putting in order of element _Opt, Sq _Opt=Sq (Index_opt).

Sq _opt＝{617，599，571，547，509，487，461，439，419，389，367，347，313，283，269，241，227，197，179，157，137，149，167，191，211，233，257，277，307，331，353，379，401，431，449，467，499，523，563，587，607}

The frequency interval of optimizing is Δ F for rounding the back _Opt=c/Sq _Opt

Δ F _Opt={ 486224,500835,525394,548446,589391,616016,650759,683371,715990,771208,817439,864553,958466,1060071,1115242,1244813,1321586,1522843,1675978,1910828,2189781,2013423,1796407,1570681,1421801,1287554,1167315,1083032,977199,906344,849858,791557,748130,696056,668151,642398,601202,573614,532860,511073,494234} (unit: Hz)

Final survey frequency is

F={400.486224,400.987059,401.512453,402.060899,402.650290,403.266306,403.917065,404.600436,405.316426,406.087634,406.905073,407.769626,408.728092,409.788163,410.903405,412.148218,413.469804,414.992647,416.668625,418.579453,420.769234,422.782657,424.579064,426.149745,427.571546,428.859100,430.026415,431.109447,432.086646,432.992990,433.842848,434.634405,435.382535,436.078591,436.746742,437.389140,437.990342,438.563956,439.096816,439.607889,440.102123} (unit: MHz)

More than be in 400MHz～440.5MHz frequency band, a survey frequency design example during N=41.Equally, at other frequency band ranges such as 400MHz～481MHz, when other measure frequency such as N=81, can design the survey frequency of corresponding optimization, the present invention no longer sets forth.

Step (5). emission, receiving node time synchronized

The foundation of estimation interference distance is the difference of two receiving node relative phases, and time synchronization error will cause the error of phase estimation.Adopt two receiving node C, D can eliminate the x time t of node _A, t _BTo measuring the influence of phase place, namely the transmitting node synchronous error does not influence measurement.

And the synchronous error Δ t of receiving node C, D _CDTo phase place

Influence can quantize 2 π (f ₁-f ₂) Δ t _CDAs the difference on the frequency (f that transmits usually ₁-f ₂)＜1KHz, the phase error of 1 μ s synchronous error correspondence is 2 π (f so ₁-f ₂) Δ t _CD=2 π * 10 ^-3Therefore, the synchronization accuracy of 1 μ s is enough.And existing network clocking synchronous protocol just can reach the synchronization accuracy of microsecond level.

Do not use the length of a game of network range synchronous in the interfeerometry ranging, but the node that only participates in the synchronous current range finding combination and only remaining on during the one-shot measurement.In the interfeerometry ranging, host node initiates to measure by broadcast, contain another sending node, measurement type (fine setting or range finding), transmitted power in the message, also specified the moment (local zone time with host node is specified) in a future simultaneously, initiate measurement constantly at this.Stamping precise time before message is sent stabs.The recipient is converted to local zone time with timestamp, with the local zone time after the conversion timer is set, and transmits broadcast simultaneously.Can make node begin range operation at synchronization by this agreement.

Step (6). interfere the envelope phase difference to be estimated

Transmission frequency is close simultaneously for two source node A, B, is respectively f ₁, f ₂The high_frequency sine wave signal, make δ=(f ₁-f ₂)/2, and δ＜＜f ₁, δ＜＜f ₂, the difference of two frequencies is fixed value in the measurement.Two sinusoidal signals produce interference at receiving node C, D, claim f=(f ₁+ f ₂The interference source frequency is called for short for interfering the centre frequency of source signal in)/2; Note λ=c/f is for interfering source wavelength.Receiving node C, D carry out mixing, square frequency multiplication and low-pass filtering treatment to interference signal separately, and low frequency sinusoidal signal after the low-pass filtering is sampled.Utilize sample to estimate phase place and the frequency of sinusoidal signal, obtain

Phase place and the frequency approach of estimation sine wave signal are a lot, can adopt time domain approach on low-cost device.The time domain method of estimation is at first carried out running mean to raw data, with the mean value of current RSSI (received signal strength indicator) actual measured value and preceding M historical data as current RSSI reading.Secondly, judge the maximal value R of interference signal intensity by preceding 24 RSSI readings _MaxWith minimum value R _Min, its difference is defined as the amplitude A mp=|R of interference signal _Max-R _Min|.Arrange and be limited to R to the doorstep _Max-0.2 * Amp, the Xiamen is limited to R _Min+ 0.2 * Amp.RSSI reading is subsequently classified: the reading greater than Upper threshold is designated high value, less than the low value that is designated of Lower Threshold.When the RSSI reading is become high value and is become non-high value subsequently again by low value, with the centre position of the high value reading of correspondence as crest location.Two adjacent crest locations are determined cycle and the frequency of sinusoidal signal.The bias size corresponding phase of the crest location of receiving node C and D is poor.

Step (7). interference distance is estimated

The phase place of two receiving node C, D envelope poor Corresponding quaternary is apart from combination d _ABCD=d _AD-d _BD+ d _BC-d _AC, and claim d _ABCDInterference distance for four-tuple ABCD correspondence.Wherein, d _XY(X, Y ∈ A, and B, C, the D}) distance of expression nodes X, Y, as shown in Figure 1.And have

Wherein, n is unknown integer.In order to determine n, need be at n different carrier frequencies f _iLast measurement can get n equation like this

Because the number of positional number is n+1, greater than the system of equations number, system of equations (6) does not have closed solutions, can seek an immediate solution with searching method

Wherein, q _TangeBe basis

(i) the interference distance d of Gu Jiing _ABCD, round{} represents to round.Among the present invention formula (7) is called the offset search function, the interference distance value q that formula (7) obtains estimating _Range

Step (8) node location is estimated

Because node A, B, C are the anchor node of location aware, D is unknown node, so

d _ABCD-d _BC+d _AC＝d _AD-d _BD (9)

Equation (9) is determined a hyperbolic curve, if anchor point A, C are made as transmitting node, B, D are receiving node, does one group of measurement again, can get a new hyperbolic curve, and two hyp intersection points can be determined the position of D.In the practical application, a plurality of anchor point combination commonly used is finished many groups and is measured, and every group measures one is the hyperbolic curve of focus with two transmitting nodes, when noise is arranged, many hyperbolic curve does not meet at a bit, and available weights least-squares algorithm this moment (WLS) is found the solution the position of node to be positioned.

More than be the detail of complete performing step of the present invention, the effect of Frequency Design method of the present invention is mainly verified in following emulation, and simulation parameter is consistent with design example in the step (4) in the emulation.

Except with original RIPS uniformly-spaced the Frequency Design method relatively, the difference that has also compared the distance accuracy that the frequency interval that optimizes the arrangement of and tactic frequency interval cause in emulation of the present invention simultaneously is spaced validity and the necessity of order with design frequency among explanation the present invention.

In addition, when in analogous diagram of the present invention, calculating MSE, corresponding 2000 statistical averages of each noise variance value.

Owing to optimize survey frequency when design, not only considered the elimination problem of integral circumference ambiguity, be devoted to the raising of distance accuracy simultaneously.Method for designing of the present invention has reached Expected Results, as Fig. 4, Fig. 7, shown in Figure 8.From the contrast of several method, find out

(a). equifrequent partitioning method integral circumference ambiguity girth is subjected to the influence of frequency interval, and frequency interval is more little, and the integral circumference ambiguity girth is more long, and the probability that occurs integral circumference ambiguity when namely measuring is more little, but is measuring frequency one regularly, and occupied bandwidth is also more little, and distance accuracy is low.

(b). optimize the Frequency Design method based on prime number and the integral circumference ambiguity problem do not occur.

(c). among Fig. 7, Fig. 8, identical with the measurement frequency at available bandwidth, and guarantee that various measuring methods have all taken full advantage of under the available bandwidth prerequisite, optimize the frequency interval method for designing based on prime number, not only finding range is unrestricted, distance accuracy also will obviously be better than the equifrequent partitioning method (for the medium partitioning method of Fig. 7, Fig. 8 when medium phase noise, measure frequency and take entire available bandwidth, this will be cost to sacrifice finding range also, as B=81MHz among Fig. 8, N=81, uniformly-spaced the finding range of measuring method is restricted to-150m＜q_range＜150m).

Meanwhile, if do not adopt the ordering of optimization based on the frequency interval method for designing of prime number, and adopt ordering arbitrarily as arranging in proper order from small to large, distance accuracy is lower as a result, even is lower than uniformly-spaced method.This simultaneous verification the validity of the frequency interval sort method optimized among the present invention.

The above only is particular implementation example of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the variation that can expect easily or replacement all should be encompassed in protection scope of the present invention.

Claims (6)

1. based on the survey frequency system of selection of prime number sequence, its step was during radio interference was located:

(1) transmit and receive the setting of node: an interferometry comprises anchor node and node to be positioned of three location awares, and two anchor nodes are set to transmitting node, and another anchor node and node to be positioned are set to receiving node;

(2) transmitting node frequency calibration: the frequency to two transmitting nodes is calibrated, and eliminates their nominal transmission frequency deviation;

(3) interferometry frequency interval design: utilize the interval between all adjacent survey frequencies of prime number sequence structure, the set that all adjacent measurement frequencies are constituted at interval is designated as Δ F, wherein each element Δ f _i=f _I+1-f _i, f _iBe survey frequency, define the long S set q of complete cycle of an integral circumference ambiguity simultaneously, each element S q (i) is positive integer in the set, and corresponding one by one with the element of gathering among the Δ F, Sq (i)=c/ Δ f _i, the long S set q of complete cycle is made of prime number;

(4) the interferometry frequency interval optimizes the arrangement of design: utilize optimization method to determine survey frequency ordering at interval; According to the optimal sequencing of frequency interval, determine final one group of N survey frequency f _i, i=1 ... N;

(5) emission, receiving node time synchronized: utilize clock synchronization protocol receiving node synchronously, make it begin to receive operation in the identical moment;

(6) interfere the envelope phase difference to be estimated: two transmitting nodes are respectively in a pair of frequency f _iAnd f _i+ f _LThe sine wave that last transmission frequency is close, f _LBe fixing low frequency signal, two sine wave signals form interference signal at two receiving nodes; Calculate the phase place of two receiving node place interference signal envelopes respectively, obtain the poor of two envelope phases

(7) interference distance is estimated: respectively many to frequency on repeating step (2) and (6), measure a plurality of Unite and find the solution interference distance d _ABCD, single d _ABCDThe track of determined node to be positioned is a hyperbolic curve, described interference distance d _ABCD, refer to that an interferometry comprises four nodes in the radio interference location, i.e. two transmitting node A, B and two receiving node C, D, two receiving node envelope phases poor

Corresponding quaternary is apart from combination, i.e. d _ABCD=d _AD-d _BD+ d _BC-d _AC, claim d _ABCDBe the interference distance of four-tuple ABCD correspondence, wherein, d _XYThe distance of expression nodes X, Y, X, Y ∈ { A, B, C, D};

(8) node location is estimated: use the combination of different anchor nodes and node to be positioned, obtain different d _ABCDAnd hyperbolic curve, many hyperbolic curve intersection points are node location to be positioned.

In the radio interference according to claim 1 location based on the survey frequency system of selection of prime number sequence, it is characterized in that described step (3), with the interfeerometry ranging medium frequency at interval design problem be converted into the long sequences Design problem of complete cycle, it is 1 condition that the number that constitutes the long sequence of complete cycle needs to satisfy arbitrarily highest common factor between any two.

3. based on the survey frequency system of selection of prime number sequence, it is characterized in that described step (3) during radio interference according to claim 1 and 2 is located, the production method of the long set of complete cycle is:

Produce K prime number set of arranging according to ascending order, and from K set, carry out L and doubly extract, namely from set, take out an element every L element, to increase the difference between prime number, obtain K/L prime number as the long candidate collection P of complete cycle _r, wherein, integer K is much larger than the measurement frequency number of interfeerometry ranging, integer L value L=2.

4. based on the survey frequency system of selection of prime number sequence, it is characterized in that described step (3) during radio interference according to claim 3 is located, survey frequency building method at interval:

From the long candidate collection P of complete cycle _rThe middle N+1 of a selection continuous prime number constitutes prime number subclass Sq={P _r(i), P _r(i+1) ... P _r(i+N-1), P _r(i+N) }, this prime number set is Δ f with the corresponding relation of frequency interval _j=c/Sq (j), Sq (j)=P _r(i+j-1), c is the light velocity, determines this section prime number reference position i by way of search, makes the top n prime pair is answered among the Sq frequency interval sum greater than bandwidth B, namely

$\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\Δf}}_j=\underset{j=i}{\overset{i+N-1}{\mathrm{\Σ}}}(c/P_r\left(j\right))>B$

Simultaneously, the back N prime pair frequency interval sum of answering is smaller or equal to bandwidth B, namely

$\underset{j=2}{\overset{N+1}{\mathrm{\Σ}}}{\mathrm{\Δf}}_j=\underset{j=i+1}{\overset{i+N}{\mathrm{\Σ}}}(c/P_r\left(j\right))\≤B$

Δ F={ Δ f _j| j=2 ... N+1} is the frequency interval set of final structure;

Perhaps select several sections continuous prime numbers, make it add up to N, and corresponding frequency interval sum almost takes available measurement bandwidth.

5. based on the survey frequency system of selection of prime number sequence, it is characterized in that described step (4) during radio interference according to claim 1 is located, the frequency interval sort method designs by following thought intuitively:

To the rearrangement of frequency interval sequence, its element is had increase progressively the character of afterwards successively decreasing earlier, thereby make survey frequency densely distributed at the frequency band two ends, distribute sparse at band center; When survey frequency N is odd number, the frequency interval sequence at first by descending sort, is obtained gathering Δ F={ Δ f ₁, Δ f ₂, Δ f ₃... Δ f _N, the element rearrangement in will gathering then is Δ F _Opt={ Δ f _N, Δ f _N-2, Δ f _N-4... Δ f ₃, Δ f ₁, Δ f ₂, Δ f ₄... Δ f _N-3, Δ f _N-1, when N was even number, the set of rearrangement was Δ F _Opt={ Δ f _N-1, Δ f _N-3, Δ f _N-5... Δ f ₃, Δ f ₁, Δ f ₂, Δ f ₄... Δ f _N-2, Δ f _N.

In the radio interference according to claim 1 location based on the survey frequency system of selection of prime number sequence, it is characterized in that described method be applicable to node locating in the wireless network of laying on a large scale and among a small circle in node locating in the wireless sensor network.

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