CN102073031A - Sensor network-based environmental monitoring system and method - Google Patents

Abstract

The invention discloses a sensor network-based environmental monitoring system and a sensor network-based environmental monitoring method, and belongs to the fields of acoustic positioning and wireless data network transmission. The system comprises three parts, namely a monitoring center, an acoustic sensor and a wireless sensor network; and the method comprises the following steps of: acquiring a sound signal transmitted by a sniper target sound source through the acoustic sensor, measuring the time difference for the sound signal to reach different acoustic sensor nodes, and calculating a coordinate of the sound source by combining the position and sound velocity of the known acoustic sensor nodes; positioning the position of a mobile node carried by nearby related personnel in real time by using the monitoring center through the wireless sensor network, calculating the position of the nearby related personnel relative to the target sound source and transmitting the calculated information to each node of the wireless sensor network; therefore, the related personnel can sense the position of the target sound source relative to the related personnel in real time. The invention has the advantages of low cost, low power consumption, adoption of a universal wireless sensor network, design miniaturization, good real-time property and high positioning accuracy.

Description

Environmental monitoring system and method based on sensor network

Technical field

The present invention relates to a kind of system and method that utilizes sensor network to realize the location, belong to acoustics location and wireless sensor network positioning field.

Background technology

Along with fast development of information technology, information war will become the principal mode of future war.If existing armament systems are likened to people's bone and muscle, command system likens people's nervous centralis to, and sensor network nodes is exactly the competent cell of nerve endings so.

The wireless network of the oriented mission that wireless sensor network is made up of a plurality of nodes, it can be monitored target information in real time by all kinds of microsensors, by embedded computational resource information is handled, and information is sent to the long-distance user by cordless communication network.Have that volume is little, intensive, stochastic distribution, fast the characteristics of disposing.The acoustics location technology is to utilize acoustic sensing device to receive acoustical signal, by electronic installation the acoustical signal that receives is carried out the technology that analyzing and processing is determined sound source position again.The sounding sensor has good concealment, and strong security is not subject to characteristics such as interference.The sound-detection location can remedy the situation that wireless sensor network is difficult for the perception noncooperative target.With above-mentioned both combine and be fit to very much be applied in the rugged environment, comprise gathering intelligence about the enemy, anti-terrorism, monitoring battle field information, judging many-sided purposes such as biological chemistry attack.Therefore the research of this two aspect has obtained using widely in military field, and has become the important component part of environmentally sensitive monitoring system.

The sniper causes great threat easily to personnel/vehicle, because sniper's exactissima diligentia disguise even therefore it is in radio sensor network monitoring range, also possibly can't be sensed by wireless sensor network.But; receive the acoustical signal of sniping gun by the sounding sensor that is equipped with; adopt the acoustics localization method to determine sniper's position; simultaneously calculate the sniper with respect to related personnel (as: soldier, security personnel) position and direction by wireless sensor network again; can reach the purpose of accurate riposte enemy, protection oneself, thereby improve fighting efficiency greatly.Though someone proposes the scheme that both combine is applied to the battlefield monitoring, Master's thesis " based on the auditory localization technical research of the wireless sensor network node " (Northcentral University of writing as Wang Jianliang, in June, 2009), with auditory localization and wireless data transmission combination, but the just simple wireless mode transmission auditory localization data that adopt do not realize the relative positioning of wireless sensor network node to sound source; There has been Wang Xue the patent aspect by in November, 2010, " wireless measurement method of auditory localization " (Chinese patent that Bi Daowei etc. propose, application number 200810118829.6), this invention adopts the method that receives the signal energy location to carry out auditory localization, but it is similar to the former, all do not realize the combination of wireless sensor network location technology and auditory localization technology, do not satisfy in the actual environment related personnel the application demand of target sound source information.

Summary of the invention

Technical matters to be solved by this invention is to locate the realization that combines at the deficiency that prior art exists by wireless sensor network node location and acoustics the relative position of target is surveyed.

The present invention is based on the environmentally sensitive monitoring system of sensor network, comprise monitoring center, sounding sensor and wireless sensor network; System comprises a plurality of sounding sensor nodes, wireless sensor network is made of a plurality of mobile nodes, beaconing nodes and a Centroid, wherein communicate by letter with wireless mode by antenna between mobile node, beaconing nodes and Centroid, Centroid is connected with monitoring center respectively with the sounding sensor node.

Wherein, described sounding sensor node comprises signal receiving circuit, filter amplification circuit, hysteresis comparator circuit; Signal receiving circuit is used for collected sound signal, the input end of signal receiving circuit output termination filter amplification circuit, and the output terminal of filter amplification circuit connects the input end of hysteresis comparator circuit.

Wherein, described monitoring center comprises microprocessor and supports circuit, crystal oscillating circuit, code translator, charactron, trigger and reset circuit, voltage stabilizer; The trigger of monitoring center links to each other with microprocessor, and crystal oscillating circuit links to each other with microprocessor.Code translator links to each other with microprocessor and drives charactron.Voltage stabilizer provides stabilized power source for entire circuit.

Monitoring method based on the environmentally sensitive monitoring system of sensor network comprises the steps:

When a) sound source was sounded signal, the sounding node sensed voice signal and voice signal is converted into electric signal; Monitoring center receives described electric signal and calculates the sound source coordinate;

B) monitoring center is the Centroid of sound source coordinate notice wireless sensor network, and the Centroid networking also sends positioning request signal to mobile node;

C) after mobile node successfully networks, regularly to beaconing nodes exchange correlation distance value information; Beaconing nodes sends information to Centroid after the information such as correlation distance value of having gathered with mobile node;

D) Centroid is sent to monitoring center with information by data port, mobile node coordinate, the sound source positional information with respect to mobile node is calculated by distance between mobile node and beaconing nodes and known beaconing nodes location solution by monitoring center, and by Centroid positional information is sent to corresponding mobile node.

The invention has the beneficial effects as follows: the present invention is the military Position Research based on wireless sensor network, finally can be used for battlefield/anti-terrorism monitors in real time, the realization of its wireless sensor network localization part is set up on the cordless communication network basis, characteristics such as it is low that wireless sensor node has energy consumption, and survivability is strong are suitable for large scale deployment.And, merged that the practicality of this system improves greatly after the auditory localization, as aim at foreign environments such as battlefield/anti-terrorism and survey, this is studied and be used targetedly, will improve fight/anti-terrorism efficient, promote fighting capacity, for powerful guarantee is made in the war of winning under the high-technology condition.

Description of drawings

Fig. 1 is a system construction drawing;

Fig. 2 is a sounding node locating synoptic diagram;

Fig. 3 is wireless senser TOF range measurement principle figure;

Fig. 4 is range finding positioning principle figure;

Fig. 5 is a sounding sensor node hardware design block diagram;

Fig. 6 is monitoring center's hardware design block diagram;

Fig. 7 is a wireless sensor node software design process flow diagram, (a) Centroid, (b) mobile node, (c) beaconing nodes;

Fig. 8 is monitoring center's software flow pattern;

Embodiment

Be elaborated below in conjunction with the technical scheme of accompanying drawing to invention:

Wireless sensor network node can be distributed in geographic area very widely, need not the underlying basis facility, can dispose characteristics such as self-organization, disguised strong, zmodem and cost are lower fast but have.Sound has its singularity, is not subjected to the restriction of sight line and visibility, good concealment, and strong security is not subject to disturb.The two is combined can be deployed in a large number that the people carries out information search in inaccessiable hazardous location in emergency situations or the battlefield, thereby helps the monitoring of battle field information and the raising of whole battle efficient.

Referring to Fig. 1

In order to remedy the existing defective that wireless mode transmission auditory localization information only is provided, the invention provides a kind of battlefield sensing and monitoring system based on wireless sensor network and sounding sensor, be illustrated in figure 1 as the entire system structure.This system comprises monitoring center, sounding sensor and three parts of wireless sensor network.Utilize on the one hand the voice signal of the burst in the sounding sensor search coverage, send information to monitoring center and handle, thereby effectively catch and locate; On the other hand, monitoring center utilizes the positional information aggregation process of wireless sensor network to the entrained mobile node of related personnel, make the related personnel of each dispersion can both receive the burst sound source position of oneself relatively, and then acoustic target hit effectively, thereby realized the target of real-time monitoring.

Referring to Fig. 2

Among Fig. 2, P is a sound source, and the A point is for having the node of processing capacity harmony brake; B, C, D, E are the sounding sensor node.During system works, set handling node A makes it be in standby condition; When sound source P sent acoustical signal to the sounding part of A, it triggered the processing section of A, and was provided with by the processing section and write down at that time Ta constantly, and other sensors trigger the processing section of A too, constantly are respectively Tb, Tc, Td, Te.When the A point receive start the clock after all the sensors is sent pulse electrical signal poor.

$\left.\begin{array}{c}\mathrm{Tab}=\mathrm{Tb}-\mathrm{Ta}\\ \mathrm{Tac}=\mathrm{Tc}-\mathrm{Ta}\\ \mathrm{Tad}=\mathrm{Td}-\mathrm{Ta}\\ \mathrm{Tae}=\mathrm{Te}-\mathrm{Ta}\end{array}\right\}$

Obtain after the mistiming, calculate the position that P is ordered in conjunction with the known coordinate of ABCDE.Record sound source P point acoustical signal and arrive A point and the mistiming Tab that arrives other each points, Tac, Tad, Tae according to known ABCDE coordinate, calculates P point position.

$\left\{\begin{array}{c}\sqrt{{(\mathrm{xp}-\mathrm{XA})}^2-{(\mathrm{yp}-\mathrm{YA})}^2+{(\mathrm{zp}-\mathrm{ZA})}^2}-\sqrt{{(\mathrm{xp}-\mathrm{XB})}^2+{(\mathrm{yp}-\mathrm{YB})}^2+{(\mathrm{zp}-\mathrm{ZB})}^2}=\mathrm{Tab}*c\\ \sqrt{{(\mathrm{xp}-\mathrm{XA})}^2+{(\mathrm{yp}-\mathrm{YA})}^2+{(\mathrm{zp}-\mathrm{ZA})}^2}-\sqrt{{(\mathrm{xp}-\mathrm{XC})}^2+{(\mathrm{yp}-\mathrm{YC})}^2+{(\mathrm{zp}-\mathrm{ZC})}^2}=\mathrm{Tac}*c\\ \sqrt{{(\mathrm{xp}-\mathrm{XA})}^2+{(\mathrm{yp}-\mathrm{YA})}^2+{(\mathrm{zp}-\mathrm{ZA})}^2}-\sqrt{{(\mathrm{xp}-\mathrm{XD})}^2+{(\mathrm{yp}-\mathrm{YD})}^2+{(\mathrm{zp}-\mathrm{ZD})}^2}=\mathrm{Tad}*c\\ \sqrt{{(\mathrm{xp}-\mathrm{XA})}^2+{(\mathrm{yp}-\mathrm{YA})}^2+{(\mathrm{zp}-\mathrm{ZA})}^2}-\sqrt{{(\mathrm{xp}-\mathrm{XE})}^2+{(\mathrm{yp}-\mathrm{YE})}^2+{(\mathrm{zp}-\mathrm{ZE})}^2}=\mathrm{Tae}*c\end{array}\right.$

Referring to Fig. 3,4

Among the present invention, the range finding location algorithm of wireless senser is to select suitable ranging technology, adopt RSSI and TOF location algorithm to measure the distance that unknown node arrives three or more beaconing nodes, behind the range information that collects unknown node and beaconing nodes, use least square method to merge the computing node position.

1) RSSI ranging technology

Receiving node calculates the loss in communication process of signal according to the intensity of receiving signal in the RSSI range finding, utilizes the relation between signal attenuation and the propagation distance to calculate distance.

Path loss model in the free space is as follows:

Loss＝32.44+10klgd ₀+10klgf

In the formula, general d ₀Be 1m, f is frequency (MHz); K is the path attenuation factor, generally between 2～5.

In actual application environment, because factors such as multipath, diffraction, barrier interference can be used logarithm-normal distribution model:

PL(d)＝PL ₀+10klg(d/d ₀)+X _σ

In the formula, PL (d) is for passing through apart from the path loss behind the d, and unit is dBm; X _σFor average is zero Gaussian distribution random number, the standard deviation scope is 4～10; PL ₀Be process reference distance d ₀After path loss.

Signal strength values when unknown node receives the beaconing nodes signal can be obtained by following formula:

RSSI＝P+G-PL(d)

In the formula, P is an emissive power, and G is an antenna gain.

For certain concrete environment, can set up the model equation of RSSI and distance according to the empirical data of basic principle model and a large amount of actual measurements.So the relation between RSSI and actual range can be reduced to:

RSSI＝c ₁×lgd+c ₂

In the formula, c ₁And c ₂(dBm) change with environment change.As long as can determine c more exactly ₁And c ₂Value, just can access the relation of RSSI and actual range more accurately.

2) TOF ranging technology

The TOF range finding is by the distance between propagation of wireless signal time measured node.Range measurement principle obtained euclidean distance between node pair by the mensuration of wireless signal bi-directional time between two nodes as shown in Figure 3 when TOF surveyed.At first, at a time send a signal to node 2, meanwhile start the timer in the node 1 by node 1; Node 2 will include information isoparametric information frame of turnaround time in node 2 again and postback to node 1 behind the signal that receives node 1; The T.T. t that timer record information was transmitted when node 1 was received the information of node 2 _Tot1Then node 1 can be extrapolated the direct passing time t of wireless signal between two nodes _Tof, the formula of embodying is:

t _tof＝(t _tot1-t _tx1-t _rx1-t _cor1-t _tat2-t _tx2-t _rx2-t _cor2)/2

In the formula, t _Tx1, t _Tx2Be the wireless transceiver transmitting time; t _Rx1, t _Rx2Be the wireless transceiver time of reception; t _Cor1, t _Cor2Be the time correction, this value is relevant with factor such as internodal signal intensity; t _Tat2For node 2 is received node 1 signal and is postbacked turnaround time between the signal.

If the light velocity is c, then two internodal distances are:

d＝t _tof×c

3) least square method

Suppose to be respectively (x at deployed in areas A, B, three beaconing nodes coordinates of C ₁, y ₁, z ₁), (x ₂, y ₂, z ₂), (x ₃, y ₃, z ₃), they are respectively d to the distance of unknown node D ₁, d ₂, d ₃, the coordinate of establishing unknown node for (x, y, z), as shown in Figure 4.

Then can set up following system of equations:

$\left\{\begin{array}{c}{(x-x_1)}^2+{(y-y_1)}^2+{(z-z_1)}^2=d_1^2\\ {(x-x_2)}^2+{(y-y_2)}^2+{(z-z_2)}^2=d_2^2\\ {(x-x_3)}^2+{(y-y_3)}^2+{(z-z_3)}^2=d_3^2\end{array}\right.$

If the individual beaconing nodes of n (n 〉=3) is arranged in the zone, their coordinate corresponds to (x _n, y _n, z _n), they correspond to d to the distance of unknown node _n, the coordinate of establishing unknown node for (x, y, z).Then can set up following system of equations:

$\left\{\begin{array}{c}{(x-x_1)}^2+{(y-y_1)}^2+{(z-z_1)}^2={\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HDA0000037040730000021.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2\\ {(x-x_2)}^2+{(y-y_2)}^2+{(z-z_2)}^2={\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">d</figure-callout>}}_2^2\\ M\\ {(x-x_n)}^2+{(y-y_n)}^2+{(z-z_n)}^2={\mathrm{<figure-callout\; id="2"\; label="d\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">d</figure-callout>}}_n^{}\end{array}\right.$

Arrangement is system of linear equations form: AX=B

In the formula,

$A=\left[\begin{array}{ccc}2(x_1-x_n)& 2(y_1-y_n)& 2(z_1-z_n)\\ M& M& M\\ 2(x_{n-1}-x_n)& 2(y_{n-1}-y_n)& 2(z_{n-1}-z_n)\end{array}\right]$

$B=\left[\begin{array}{c}{x}_1^2-{\mathrm{<figure-callout\; id="2"\; label="x\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">x</figure-callout>}}_n^{}+{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000037040730000021.png"\; state="\{\{state\}\}">y</figure-callout>}}_1^2-{\mathrm{<figure-callout\; id="2"\; label="y\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">y</figure-callout>}}_n^{}+{\mathrm{<figure-callout\; id="1"\; label="z"\; filenames="HDA0000037040730000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_1^2-{\mathrm{<figure-callout\; id="2"\; label="z\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">z</figure-callout>}}_n^{}+d_n^2-{\mathrm{<figure-callout\; id="1"\; label="d"\; filenames="HDA0000037040730000021.png"\; state="\{\{state\}\}">d</figure-callout>}}_1^2\\ M\\ x_{n-1}^2-{\mathrm{<figure-callout\; id="2"\; label="x\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">x</figure-callout>}}_n^{}+y_{n-1}^2-{\mathrm{<figure-callout\; id="2"\; label="y\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">y</figure-callout>}}_n^{}+z_{n-1}^2-{\mathrm{<figure-callout\; id="2"\; label="z\; n"\; filenames="HDA0000037040730000031.png"\; state="\{\{state\}\}">z</figure-callout>}}_n^{}+d_n^2-d_{n-1}^2\end{array}\right],X=\left[\begin{array}{c}x\\ y\\ z\end{array}\right]$

Find the solution matrix equation and can obtain the unknown node coordinate:

$\hat{X}={\left(A^{T}A\right)}^{-1}{A}^{T}b$

Referring to Fig. 5

Circuit such as Fig. 5 of the actual connection of sounding sensor node hardware, it is mainly by signal receiving circuit, filter amplification circuit, hysteresis comparator circuit is formed.When certain sound made the microphone vibration, entire circuit also can be along with variation, and output at last has the magnitude of voltage that height changes, and used as the time clock of d type flip flop, triggers follow-up circuit in circuit system.

1) signal receiving circuit

Microphone and resistance string joining power, for microphone work provides a direct current biasing, conducting when microphone is experienced sound and intensity and reached certain index begins to gather acoustical signal.

2) filter amplification circuit

Form by electric capacity, resistance and triode, the AC compounent of microphone voltage signal can be extracted and amplify, obtain the easy to handle large-signal through triode by capacitance resistance filtering.

3) hysteresis comparator circuit

Utilize amplifier to form a hysteresis comparator, the signal after previous step is amplified carries out sluggishness relatively, judges whether signal is effective.Choose comparative voltage (for the quiescent voltage of previous step output, i.e. DC component), the thresholding width of suitable selection hysteresis comparator (the sluggish thresholding of 3.8v and 1.3v is proper, has guaranteed the sensitivity and the stability of sensor).Compare with comparative voltage after the previous step signal is come, signal effectively just can produce the output voltage of height change, for the trigger use of follow-up circuit.

Referring to Fig. 6

Monitoring center is the core of total system, is responsible for mission criticals such as data processing and transmission, and monitoring center's hardware circuit as shown in Figure 6.Monitoring center's modular circuit mainly comprises microprocessor and supports circuit, crystal oscillating circuit, code translator, trigger and reset circuit, voltage stabilizer.Trigger receives the output signal of sounding sensor node, produces step signal, as the input signal of microprocessor.Because sound arrives the asynchronism(-nization) of different nodes, therefore d type flip flop produces also difference of step signal rising edge, read in step signal and timing by microprocessor, after all arriving, handle all road signals, can obtain the mistiming that each input signal arrives microprocessor, in conjunction with the position and the velocity of sound of known node, calculate just and can obtain the sound source coordinate again.

Microprocessor is communicated by letter with the wireless sensor network Centroid by the data-interface standard, thereby realizes the transmission of data message.Microprocessor internal has the full duplex serial communication interface, and these parts can carry out the transmission and the reception of data simultaneously.

The wireless senser hardware node is provided by Jennic company, hardware module is integrated all radio frequency components and wireless microcontroller, employing modular design mode.Module adopts single-chip to manage, and has SMA antenna connector, and signal transmission power is strong, and propagation distance is far away, and networking flexibility is well positioned to meet the requirement of wireless sensor network.Integrated JN5147 module on the sensor node, Temperature Humidity Sensor, RS232 DLL (dynamic link library), RS485 interface, module pin draw winding displacement, power circuit, 3 status indicator lamps, 2 programming buttons etc.The risc processor that the JN5147 built-in chip type is a 32 disposes the wireless transceiver that meets IEEE 802.15.4 standard of 2.4GHz frequency range, the ROM of 192Kb and the RAM of 96Kb.

Referring to Fig. 7 (a) and (b), (c)

When the center node receives the positioning request signal that monitoring center sends mobile node, start network, waiting facilities adds network, in case networking success, mobile node and beaconing nodes exchange distance value related data, beaconing nodes arrives Centroid with data transmission again, forwards the data to monitoring center by Centroid at last and handles.After result of calculation is come out, postback again to Centroid and whole network.

Referring to Fig. 8

Monitoring center's program mainly contains initialization, data are read in and detection, data processing, numerical evaluation, data output unit.Program circuit as shown in Figure 8.At first carry out initialization and define some variablees.If data are read in from microprocessor P1 mouth then are handled sounding sensor node signal.Read in circulating behind the P1 mouth one writing, up to the input four all uprise till.This is an outer loop, if this part finishes, reading in also of data just finished.And inner adopt inquiry mode to detect data whether to have new signal to arrive, if having, if then record time this moment and the record value of reading in be not then skip.Here also have some internal clocking control statements, realize clocking capability.What input signal was used is the step signal that has rising edge, by adjusting hopping time, just can obtain the different data of importing separately constantly.Carry out simple process after data are read in, just can obtain the time that signal arrives different nodes.Calculate through the acoustics location algorithm again and just can obtain the sound source coordinate.If data are read in from microprocessor P3 mouth then are handled the wireless sensor node signal.The P3 mouth circulated read in, up to mobile node till the data of each beaconing nodes all run through in the network.If this part finishes, reading in also of data just finished.The packet that Centroid transmits is resolved, call the wireless sensor node location algorithm then and just can obtain the mobile node coordinate.Carry out azimuth information at last and resolve, can calculate the orientation of sound source, at last information is sent back to whole network, make mobile node reach accurate location sound source with respect to mobile node.

Claims (4)

1. the environmentally sensitive monitoring system based on sensor network is characterized in that comprising monitoring center, sounding sensor and wireless sensor network; System comprises a plurality of sounding sensor nodes, wireless sensor network is made of a plurality of mobile nodes, beaconing nodes and a Centroid, wherein communicate by letter with wireless mode by antenna between mobile node, beaconing nodes and Centroid, Centroid is connected with monitoring center respectively with the sounding sensor node.

2. the environmentally sensitive monitoring system based on sensor network according to claim 1 is characterized in that described sounding sensor node comprises signal receiving circuit, filter amplification circuit, hysteresis comparator circuit; The input end of signal receiving circuit output termination filter amplification circuit, the output terminal of filter amplification circuit connects the input end of hysteresis comparator circuit.

3. the environmentally sensitive monitoring system based on sensor network according to claim 1 is characterized in that described monitoring center comprises microprocessor and supports circuit, crystal oscillating circuit, code translator, charactron, trigger and reset circuit, voltage stabilizer; The trigger of monitoring center links to each other with microprocessor, and crystal oscillating circuit links to each other with microprocessor, and code translator links to each other with microprocessor and drives charactron, and voltage stabilizer provides stabilized power source for entire circuit.

4. the monitoring method based on the described environmentally sensitive monitoring system based on sensor network of claim 1 is characterized in that comprising the steps:

When a) sound source was sounded signal, the sounding node sensed voice signal and voice signal is converted into electric signal; Monitoring center receives described electric signal and calculates the sound source coordinate;

B) monitoring center is the Centroid of sound source coordinate notice wireless sensor network, and the Centroid networking also sends positioning request signal to mobile node;

C) after mobile node successfully networks, regularly to beaconing nodes exchange correlation distance value information; Beaconing nodes sends information to Centroid after the information such as correlation distance value of having gathered with mobile node;

D) Centroid is sent to monitoring center with information by data port, mobile node coordinate, the sound source positional information with respect to mobile node is calculated by distance between mobile node and beaconing nodes and known beaconing nodes location solution by monitoring center, and by Centroid positional information is sent to corresponding mobile node.

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