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Title:OCENJEVANJE KOTA PRIHODA SIGNALA Z UPORABO NEUSMERJENIH ANTEN IN MERJENJA MOČI SIGNALA
Authors:ID Malajner, Marko (Author)
ID Gleich, Dušan (Mentor) More about this mentor... New window
Files:.pdf DR_Malajner_Marko_2013.pdf (26,14 MB)
MD5: 4425D38D48EA638D1156EE577941033D
PID: 20.500.12556/dkum/e51ccfd1-9a4f-45a4-843e-c289508d105f
 
Language:Slovenian
Work type:Dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FERI - Faculty of Electrical Engineering and Computer Science
Abstract:V disertaciji se ukvarjamo s problemom ugotavljanja pozicije senzorjev, ki so povezani v brezžična senzorska omrežja (BSO). Pri izbiri koncepta ugotavljanja pozicije smo upoštevali glavni cenilki teh omrežij in v njih povezanih senzorjev, to je (i) minimizacija potrošnje energije in (ii) minimizacija cene senzorja. Tema cenilkama najbolje zadostimo, če uporabljamo vire, ki so na voljo v topologiji brezžičnega senzorskega omrežja in v delovanju radijskega dela senzorjev. Na tej osnovi deluje mnogo metod določanja pozicije senzorjev. Izmed njih smo se v tezi omejili na metodo, ki temelji na merjenju kota prihoda RF signala (AoA). Kot merimo s posebnimi, vrtečimi se vozlišči v omrežju, v katerih kot ocenimo s pomočjo merjenja moči sprejetega RF signala iz ostalih senzorjev omrežja v njegovi okolici. Sprejeto moč signala (RSSI) merijo vsi radijski moduli senzorjev, ki komunicirajo skladno s standardom IEEE 802.15.4. Možnost merjenja AoA smo omejili na referenčne enote (svetilnike), ki poznajo svojo pozicijo in so tudi iz vidika strojne opreme kompleksnejše. V BSO imajo lahko referenčne enote tudi nalogo usmerjati promet in zbiranje podatkov iz ostalih senzorskih enot. Ostale “iskane” enote so navadne enote brez posebnosti. Za eksperimentalno potrditev raziskav, na katerih temelji ta disertacija smo razvili novo strojno in programsko opremo za ocenjevanje AoA. Programska oprema temelji na algoritmih, ki jih v disertaciji predlagamo kot originalni prispevek disertacije. Algoritmi izkoriščajo posebnosti dipolnih anten: (i) sevalna karakteristika magnetnega polja (H) je izotropna, (ii) sevalna karakteristika električnega polja (E) pa je anizotropna v zelo ozkem področju. Ta usih sprejetega RF signala iz senzorja, katerega pozicijo iščemo, smo izkoristili za ugotavljanje smeri, v kateri se ta nahaja. Ta, rečemo lahko v primerjavi z ostalimi AoA tehnikami, ki temeljijo na iskanju maksimuma usmerjenega polja, nekonvencionalna metoda, omogoča natančnejšo izmero kota, uporablja standardne (mikrostrip) dipolne antene tako v svetilnikih kot ostalih senzorjih ter uporablja preprostejšo dodatno strojno opremo in preprostejše algoritme. Ker se uporablja dipolna antena, je lahko svetilnik tudi usmerjevalnik podatkov v omrežju. V eksperimentih smo se omejili na optično vidno linijo (LOS) med svetilnikom in senzorji. Vsaka ovira, ki zastira vidno linijo povzroči neželene odmeve radijskega signala in s tem oteženo oceno AoA. Omejili smo se tudi na stacionarna senzorska omrežja. Vozlišča ne spreminjajo lege med ocenjevanjem AoA. Za eksperimentalno potrditev teze smo razvili in izdelali tri merilne sisteme: (i) sistem s svetilnikom s štirimi dipolnimi (mikrostrip) antenami nameščenimi na rotirajoči plošči (ii) sistem s svetilnikom z eno rotirajočo dipolno (mikrostrip) anteno in (iii) sistem s svetilnikom z dvanajstimi (mikrostrip) dipolnimi antenami razporejenimi na obodu mirujoče okrogle plošče. Za vsak sistem smo s programsko opremo prilagodili algoritem ugotavljanja smeri posebnostim strojne opreme. Vsi sistemi so potrdili našo tezo. Dobljeni eksperimentalni rezultati se seveda medsebojno razlikujejo v točnosti ocene AoA.
Keywords:brezžična senzorska omrežja, RSSI, kot prihoda RF signala, neusmerjena antena
Place of publishing:Maribor
Publisher:[M. Malajner]
Year of publishing:2013
PID:20.500.12556/DKUM-40312 New window
UDC:004.5:004.8/.9(043.3)
COBISS.SI-ID:16877334 New window
NUK URN:URN:SI:UM:DK:TZEVF5LF
Publication date in DKUM:10.05.2013
Views:2554
Downloads:339
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FERI
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Secondary language

Language:English
Title:ANGLE OF ARRIVAL ESTIMATION USING RSSI AND OMNIDIRECTIONAL ROTATABLE ANTENNAS
Abstract:In this thesis we deal with the problem of determining the position of sensors connected into Wireless Sensor Networks (WSN). When choosing the concept of determining the position we consider the following cost functions of these networks and their associated sensors, i.e., (i) the minimization of energy consumption and (ii) minimization of sensor cost. The cost functions are served best by using sources available in topology of WSN, and through operating of the radio sensors. Many methods of determining the position of sensors work in such way. In the thesis we limit ourselves to the method based on the angle measurement of the RF signals (AoA) arrival. The angles are measured by specific, rotating nodes in the network, where by estimation we measure the received power of the RF signals from other sensors in the network. The received signal strength (RSSI) is measured by all radio modules sensors that communicate in accordance with IEEE 802.15.4. AoA measurement capability is limited to the reference nodes (beacons), which know their position. These beacons have more complex hardware than other sensor nodes. The reference nodes in WSN may also serve as traffic routers and as data sink for data from other sensors. Other, so called "unknown nodes«, are ordinary units, with no particulars. For the experimental validation underlying research and studies for this thesis we have developed a new hardware and software for the assessment of AoA. The software is based on algorithms, for which we claim to be an original contribution of the dissertation. The algorithms exploit specifics of dipole antennas: (i) radiation characteristic of the magnetic field (H) is isotropic, (ii) radiation characteristics of the electric field (E) is anisotropic in a very narrow area of the spherical surface. The fading of the received RF signal from the sensor, which position we are searching, is used to determine the direction where it is located. This method, in comparison to other AoA techniques based on finding maximum oriented radiated power farfetched method, allows also requires simpler additional hardware and software. Since beacons use dipole antenna, they can also be used as router of the data networks. The experiments were constrained to optically visible distance, i.e. the case of LOS (line of Sight), between the beacon sensor and other sensors. Any barriers that obscure visible line cause unwanted echoes of radio signals and thus aggravates the measurement of AoA. For the experimental confirmation of the thesis we have developed and made three measurement testbays: (i) testbay with beacon having four dipole (microstrip) antennas mounted on a rotating plate, (ii) the testbay with beacon having a rotating dipole (microstrip) antenna and (iii) the testbay with beacon having twelve (microstrip) dipole antennas arranged on the circumference of a stationary circular plate. For each testbay we have adapted the algorithm to estimate AoA to the specifics of the used hardware. All options of the developed hardware and software have validated our thesis. The obtained experimental results, of course, differ from one another in the accuracy of AoA assessment.
Keywords:angle of arrival, omnidirectional antenna, received signal strength indicator, wireless sensor network


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