Signal Processing Methods for Multicarrier Passive Radar and Communication Systems

Keijo Pölönen

Signal Processing Methods for Multicarrier Passive Radar and Communication Systems

Julkaisun otsikon käännös: Signaalinkäsittelymenetelmiä monikantoaaltoisille passiivitutka- ja tietoliikennejärjestelmille

Keijo Pölönen

Tutkimustuotos: Doctoral Thesis › Monograph

Abstrakti

Monikantoaaltomodulaatioon pohjautuva OFDM-menetelmä mahdollistaa tehokkaan tiedonsiirron langattomassa radiokanavassa jakamalla käytettävissä oleva taajuuskaista useampaan pienempään osaan. Sen lisäksi, että OFDM-aaltomuodot soveltuvat hyvin tietoliikennejärjestelmiin, niille löytyy sovelluksia myös tutkatekniikasta. Erityisesti mielenkiintoa ovat viime aikoina herättäneet passiivitutkat, jotka eivät käytä lainkaan omia lähettimiä, vaan hyödyntävät muiden radiojärjestelmien signaaleja maalin valaisussa. Väitöskirjassa tutkitaan sekä OFDM-pohjaisten tietoliikennejärjestelmien että passiivitutkien käyttämiä signaalinkäsittelymenetelmiä. Työssä kehitetään uusia tutkasignaalin ilmaisumenetelmiä toisen sukupolven antenniverkon digitaalitelevisiosignaaleita (DVB-T2) hyödyntäville passiivitutkajärjestelmille. Työssä osoitetaan, että näillä DVB-T2-signaalin kontrollisymboleiden rakenteeseen perustuvilla menetelmillä pystytään ilmaisemaan tutkamaaleja, vaikkei tutkavastaanottimella olisi tietoa lähetetystä sisällöstä. Väitöskirjassa on esitetty analyyttisesti johdetut maalin ilmaisun tilastollisten tunnuslukujen todennäköisyysjakaumat, ja ne on verifioitu simulaatioilla käyttäen useampia erilaisia malleja tutkamaalin häilynnälle. DVB-T2-järjestelmässä lähettimet voidaan järjestää yksitaajuusverkoiksi. Tällöin useampi lähetin käyttää yhtäaikaa samaa lähetystaajuutta. Koska kaikkien lähettimien signaalit ovat muutoinkin samanmuotoisia, passiivitutkavastaanotin ei pysty helposti assosioimaan maalista mitattuja eri heijastuksia oikeisiin lähettimiin. Väitöskirjassa on kehitetty ratkaisu tähän assosiaatio-ongelmaan. Tutkimuksessa osoitetaan, että ehdotettu algoritmi saavuttaa luotettavia tuloksia jo silloinkin, kun saatavilla on ainoastaan yksi mittaustulos jokaista lähetinasemaa kohti. Simulaatioiden avulla näytetään myös, että menetelmän suorituskyky paranee merkit-tävästi mittausten määrän kasvaessa. Väitöskirjassa on kehitetty tila-aikakoodi (STBC) moniantennisiin yksitaajuusverkoissa toimiviin OFDM radiojärjestelmiin, joissa neljä lähetysantennia on jaettu kahteen erilliseen ryhmään. Tällainen tilanne voi esiintyä esimerkiksi kannettaville päätelaitteille suunnitellussa digitaalitelevisiojärjestelmässä (DVB-NGH). Tutkimuksessa osoitetaan, että kehitetyn koodin vastaanotossa pystytään käyttämään yksinkertaistettuja dekoodausmenetelmiä ilman merkittävää eroa suorituskyvyssä aiempiin vastaaviin ratkaisuihin verrattaessa. OFDM-tietoliiken-nejärjestelmien osalta väitöstutkimuksessa on kehitetty myös uusi laskennallisesti yksinkertainen radiokanavan estimointimenetelmä monikaistaiseen OFDM-teknologiaan (MB-OFDM) perustuville ultralaajakaistajärjestelmille (UWB). Iteratiivisen interpoloinnin avulla tämä algoritmi pystyy merkittävästi parantamaan pienimmän neliösumman menetelmään pohjau-tuvaa kanavaestimointia ilman olennaista laskennallisen kompleksisuuden lisäystä.

Julkaisun otsikon käännös	Signaalinkäsittelymenetelmiä monikantoaaltoisille passiivitutka- ja tietoliikennejärjestelmille
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Ohjaaja	Koivunen, Visa, Vastuuprofessori Koivunen, Visa, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6759-9
Sähköinen ISBN	978-952-60-6760-5
Tila	Julkaistu - 2016
OKM-julkaisutyyppi	G4 Monografiaväitöskirja

Tutkimusalat

ilmaisumenetelmät
monikantoaaltojärjestelmät
passiivitutka
yksitaajuusverkko

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-6760-5Lisenssi: Määrittelemätön

Siteeraa tätä

@phdthesis{74ca74f35db84da79ca70492cf2a2c9f,

title = "Signal Processing Methods for Multicarrier Passive Radar and Communication Systems",

abstract = "Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission technique that facilitates efficient information transfer through a wireless channel by dividing the large frequency bandwidth into multiple smaller subbands. Besides being a favorable technology for the communications systems, OFDM waveforms can be utilized in radar systems as well. In particular, there has been a rising interest on the passive radar systems that operate without transmitters of their own and opportunistically use the illumination offered by existing com-munication or broadcast systems that often use multicarrier modulation. This thesis develops signal processing techniques for both the OFDM-based communications systems and passive radars utilizing OFDM broadcast systems as their illuminators. The thesis proposes novel target detection algorithms for passive radar systems that are based on the sec-ond generation digital television (DVB-T2) signals. It is shown that these methods, which are based on the control symbol structure of the DVB-T2 transmission, are able to detect targets even when the information of the transmitted data is not available at the radar receiver. Analyt-ical derivations of the probability distributions of the test statistics are provided in the thesis and the results are verified through simulations using different target fluctuation models. DVB-T2 transmitters can be arranged in a single-frequency network (SFN) configuration. This means that multiple transmitters are using the same frequency at the same time. Because of the identical transmitted signal waveforms, a passive radar receiver is not able to easily associate the measurements of the target reflections with correct transmitters. A solution to this association problem is formulated in the thesis. It is shown that the proposed algorithm can produce a reliable association result already with a single measurement per each available transmitter. Simulations also verify that the performance is significantly improved when the number of measurements increases. The thesis presents a design of a space-time block code (STBC) that can be used in multiple-input multiple-output (MIMO) SFN broadcasting systems where four transmit antennas are divided into two separate groups. This kind of arrangement can be found from the handheld digital television systems (DVB-NGH). The proposed STBC is shown to provide a performance that is very close to the earlier codes designed for similar systems while at the same time de-creasing the maximum likelihood decoding complexity. Another contribution of the thesis to the OFDM communications technology is a proposal of a low-complexity channel estimation method for Multiband-OFDM (MB-OFDM) based ultra-wideband (UWB) systems. This algo-rithm improves the performance of the least squares channel estimation without a significant increase in computational complexity by introducing a novel iterative interpolation technique.",

keywords = "detection methods, multicarrier systems, passive radar, single-frequency network, ilmaisumenetelm{\"a}t, monikantoaaltoj{\"a}rjestelm{\"a}t, passiivitutka, yksitaajuusverkko, detection methods, multicarrier systems, passive radar, single-frequency network",

author = "Keijo P{\"o}l{\"o}nen",

year = "2016",

language = "English",

isbn = "978-952-60-6759-9",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "69",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Signal Processing Methods for Multicarrier Passive Radar and Communication Systems

AU - Pölönen, Keijo

PY - 2016

Y1 - 2016

N2 - Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission technique that facilitates efficient information transfer through a wireless channel by dividing the large frequency bandwidth into multiple smaller subbands. Besides being a favorable technology for the communications systems, OFDM waveforms can be utilized in radar systems as well. In particular, there has been a rising interest on the passive radar systems that operate without transmitters of their own and opportunistically use the illumination offered by existing com-munication or broadcast systems that often use multicarrier modulation. This thesis develops signal processing techniques for both the OFDM-based communications systems and passive radars utilizing OFDM broadcast systems as their illuminators. The thesis proposes novel target detection algorithms for passive radar systems that are based on the sec-ond generation digital television (DVB-T2) signals. It is shown that these methods, which are based on the control symbol structure of the DVB-T2 transmission, are able to detect targets even when the information of the transmitted data is not available at the radar receiver. Analyt-ical derivations of the probability distributions of the test statistics are provided in the thesis and the results are verified through simulations using different target fluctuation models. DVB-T2 transmitters can be arranged in a single-frequency network (SFN) configuration. This means that multiple transmitters are using the same frequency at the same time. Because of the identical transmitted signal waveforms, a passive radar receiver is not able to easily associate the measurements of the target reflections with correct transmitters. A solution to this association problem is formulated in the thesis. It is shown that the proposed algorithm can produce a reliable association result already with a single measurement per each available transmitter. Simulations also verify that the performance is significantly improved when the number of measurements increases. The thesis presents a design of a space-time block code (STBC) that can be used in multiple-input multiple-output (MIMO) SFN broadcasting systems where four transmit antennas are divided into two separate groups. This kind of arrangement can be found from the handheld digital television systems (DVB-NGH). The proposed STBC is shown to provide a performance that is very close to the earlier codes designed for similar systems while at the same time de-creasing the maximum likelihood decoding complexity. Another contribution of the thesis to the OFDM communications technology is a proposal of a low-complexity channel estimation method for Multiband-OFDM (MB-OFDM) based ultra-wideband (UWB) systems. This algo-rithm improves the performance of the least squares channel estimation without a significant increase in computational complexity by introducing a novel iterative interpolation technique.

AB - Orthogonal frequency division multiplexing (OFDM) is a multicarrier transmission technique that facilitates efficient information transfer through a wireless channel by dividing the large frequency bandwidth into multiple smaller subbands. Besides being a favorable technology for the communications systems, OFDM waveforms can be utilized in radar systems as well. In particular, there has been a rising interest on the passive radar systems that operate without transmitters of their own and opportunistically use the illumination offered by existing com-munication or broadcast systems that often use multicarrier modulation. This thesis develops signal processing techniques for both the OFDM-based communications systems and passive radars utilizing OFDM broadcast systems as their illuminators. The thesis proposes novel target detection algorithms for passive radar systems that are based on the sec-ond generation digital television (DVB-T2) signals. It is shown that these methods, which are based on the control symbol structure of the DVB-T2 transmission, are able to detect targets even when the information of the transmitted data is not available at the radar receiver. Analyt-ical derivations of the probability distributions of the test statistics are provided in the thesis and the results are verified through simulations using different target fluctuation models. DVB-T2 transmitters can be arranged in a single-frequency network (SFN) configuration. This means that multiple transmitters are using the same frequency at the same time. Because of the identical transmitted signal waveforms, a passive radar receiver is not able to easily associate the measurements of the target reflections with correct transmitters. A solution to this association problem is formulated in the thesis. It is shown that the proposed algorithm can produce a reliable association result already with a single measurement per each available transmitter. Simulations also verify that the performance is significantly improved when the number of measurements increases. The thesis presents a design of a space-time block code (STBC) that can be used in multiple-input multiple-output (MIMO) SFN broadcasting systems where four transmit antennas are divided into two separate groups. This kind of arrangement can be found from the handheld digital television systems (DVB-NGH). The proposed STBC is shown to provide a performance that is very close to the earlier codes designed for similar systems while at the same time de-creasing the maximum likelihood decoding complexity. Another contribution of the thesis to the OFDM communications technology is a proposal of a low-complexity channel estimation method for Multiband-OFDM (MB-OFDM) based ultra-wideband (UWB) systems. This algo-rithm improves the performance of the least squares channel estimation without a significant increase in computational complexity by introducing a novel iterative interpolation technique.

KW - detection methods

KW - multicarrier systems

KW - passive radar

KW - single-frequency network

KW - ilmaisumenetelmät

KW - monikantoaaltojärjestelmät

KW - passiivitutka

KW - yksitaajuusverkko

KW - detection methods

KW - multicarrier systems

KW - passive radar

KW - single-frequency network

M3 - Doctoral Thesis

SN - 978-952-60-6759-9

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Signal Processing Methods for Multicarrier Passive Radar and Communication Systems

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

Sormenjälki

Siteeraa tätä