Optimizacija kognitivnih sistema sa kontrolisanim nivoom interferencije primenom višeantenskih tehnika sa adaptivnom kontrolom snage
Optimization of cognitive systems with controlled interference level by using multi-antenna techniques with adaptive power control
Author
Blagojević, VesnaMentor
Ivaniš, Predrag
Committee members
Dukić, MiroslavĐorđević, Goran
Simić, Mirjana

Erić, Miljko
Metadata
Show full item recordAbstract
Zbog sve rasprostranjenijeg korišćenja bežičnih komunikacionih sistema koji
omogućavaju prenos podataka velikim brzinama, slobodni frekvencijski opsezi postali
su veoma ograničen i tražen resurs. Regulatorna tela koja dodeljuju licence za
korišćenje određenih opsega su već izvršila raspodelu velikog dela spektra, zbog čega
razvoj novih ili proširenje postojećih servisa predstavlja poseban izazov. Brojne analize
ukazuju da nedovoljna fleksibilnost u načinu pristupa spektru predstavlja veći problem
od samog fizičkog nedostatka slobodnih frekvencijskih opsega. Koncept kognitivnog
radio sistema predstavlja potencijalno rešenje za efikasnije korišćenje spektra.
U ovoj disertaciji analiziran je kognitivni radio sistem sa kontrolisanim nivoom
interferencije, koji podrazumeva da primarni (licencirani) i sekundarni (kognitivni)
korisnici spektra istovremeno pristupaju istom opsegu učestanosti. Sekundarnom
korisniku je dozvoljeno emitovanje signala pod uslovom da na ulazu primarnog
prijemnika ge...neriše interferenciju koja je manja od unapred definisanog praga. Ovaj
zahtev se može ispuniti korišćenjem adaptivne kontrole snage na sekundarnom
predajniku, čime se direktno ograničava kapacitet sekundarnog linka. U disertaciji je
analizana primena višeantenskih tehnika na sekundarnom linku, kojima se mogu
poboljšati performanse sekundarnog korisnika.
Razmatrana je primena diverzitija zasnovanog na kombinovanju sa maksimalnim
odnosom (Maximal Ratio Combining, MRC), kao i primena tehnike optimalne selekcije
predajne antene (Transmit Antenna Selection, TAS). Analizirana je i kombinovana
tehnika združene selekcije predajne antene i prijemnog diverzitija (Transmit Antenna
Selection/ Maximal Ratio Combining, TAS/MRC), kao i primena ortogonalnih
prostorno-vremenskih blok kodova (Orthogonal Space Time Block Codes, OSTBC).
Izvršena je analiza performansi sekundarnog sistema sa primenom svake od navedenih
tehnika i adaptivnom kontrolom snage. Analiza je data za slucaj kada se statističke
karakteristike fedinga u propagacionom okruženju mogu opisati Nakagami-m
raspodelom...
Due to massive use of wireless communication systems that are enabling data
transfer with high data rates, available frequency bands became very limited and scarce
resource. Regulatory bodies have already granted licences for exclusive spectral use of
large part of available spectrum, thus making development and expansion of new
services extremely challenging. Numerous analyses indicate that the lack of flexibility
in the spectrum access represents more significant problem than physical lack of
available frequency bands. The concept of cognitive radio represents the potential
solution, leading to the more efficient use of spectrum.
In this thesis cognitive radio system with controlled interference level is analyzed,
where primary (licensed) and secondary (cognitive) spectrum users simultaneously
access the same spectrum band. Secondary user is allowed to transmit signal under the
constraint that generated interference at the primary user’s receiver is below the
predetermined threshold.... This requirement can be achieved by applying adaptive power
control at the secondary transmitter, with the consequence of limiting the secondary link
capacity. In this thesis the application of multi-antenna techniques is analyzed, with an
aim of improvement of secondary user’s performances.
The employment of maximal ratio combining (MRC) diversity at the secondary
user’s receiver is considered, as well as the application of transmit antenna selection
(TAS) technique. Combined use of both above mentioned techniques (TAS/MRC) is
also analyzed, together with possibility of application of orthogonal space time block
codes (OSTBC) at the secondary user’s link. The analysis of the performance of the
secondary system with the application of each of these techniques and adaptive power
control is provided. The analysis is given for the case when the statistical properties of
the fading in the propagation environment can be described by Nakagami-m
distribution...
Faculty:
Универзитет у Београду, Електротехнички факултетDate:
07-04-2014Projects:
- Advanced Techniques for Efficient Use of Spectrum in Wireless Systems (RS-32028)
- Research and development of robust transmission systems for corporative networks (RS-32037)