Optimizacija diferencijalne demodulacije u radijskim sustavima s fraktalnom modulacijom

doctoral thesis

• Title (english): Differential demodulation optimization in fractal modulation wireless systems
• Author: Gordan Šišul
• Mentor: Borivoj Modlic (mentor)
• Committee member: Sonja Grgić (član povjerenstva)
• Committee member: Borivoj Modlic (član povjerenstva)
• Committee member: Vladimir Lipovac (član povjerenstva)
• Committee member: Mladen Kos (član povjerenstva)
• Committee member: Darko Žubrinić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Communication and Space Technologies); Zagreb
• Defense date and country: 2004-12-01, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Radio Communications
• Universal decimal classification (UDC): 621.3 - Electrical engineering ; 004 - Computer science and technology. Computing. Data processing

Abstract

U fraktalnoj modulaciji istovremeno se prenose podaci različitim brzinama prijenosa kroz kanal. Ova nova diverziti tehnika omogućava poboljšani prijam poruke u odnosu na standardne modulacijske postupke: ako se poruka uslijed smetnji u kanalu ne može primiti jednom brzinom prijenosa, ona se može primiti drugom brzinom prijenosa. Prethodna istraživanja uključivala su svojstva fraktalne modulacije s koherentnom demodulacijom u Gaussovom i vremenski promjenjivim kanalima. Ova disertacija nadopunjuje istraživanje demodulacije postupkom koji je puno praktičniji u pokretnim uvjetima - diferencijalnim postupkom demodulacije. Korištena su dva oblika fraktalne modulacije koja pružaju mogućnost diferencijalne demodulacije: fraktalna modulacija s DCBPSK simbolima i fraktalna modulacija s π/4 DQPSK simbolima. Pokretni radijski kanal modeliran je kao kanal sa sporim ravnim Rayleighevim zamiranjem i kao frekvencijski selektivni kanal dobiven pomoću dvije zrake koje imaju Rayleighevu razdiobu uz dodani Gaussov šum. Optimizacija demodulacije provedena je na više različitih kanala u smislu izbora skale (na svakoj skali podaci se prenose različitom brzinom) s najmanjom vjerojatnosti pogreške. Ako se iskoriste različite brzine prijenosa podataka u postupku demodulacije rezultati se poboljšavaju. Zaključno, uspoređeni su rezultati π/4 DQPSK modulacije s rezultatima fraktalne modulacije s π/4 DQPSK simbolima.

Abstract (english)

Fractal modulation simultaneously sends data at multiple rates through the channel. This novel multirate diversity strategy offers improved message recovery over conventional modulation techniques: if the message is not received at one rate due to the channel disturbances, it can be received at another rate. Previous research has demonstrated the performance of fractal modulation with coherent demodulation in Gaussian and time varying channels. Coherent demodulation is not suitable for mobile channels. So, this thesis extends the investigation of demodulation which is more practical in mobile conditions - differential demodulation. Two types of fractal modulation are implemented which offer differential demodulation: fractal modulation with DCBPSK symbols and fractal modulation with π/4 DQPSK symbols. The mobile radio environment was modeled as a slow Rayleigh flat fading channel and a frequency selective, two-ray, Rayleigh fading channel with additive Gaussian noise. Demodulation optimization was carried out for all channel types in the sense of scale selection (each scale is of different data rate) for minimal error rate. Improvement in fractal demodulation performance may be achieved when multiple rates are used for demodulation. Finally, a comparison of π/4 DQPSK modulation and fractal modulation with π/4 DQPSK symbols is carried out.

• Keywords: Fraktalna modulacija; diferencijalna demodulacija; waveleti; diskretna wavelet transformacija; radijski kanal; zamiranje; diverziti; radijski sustavi
• Keywords (english): Fractal modulation; differential demodulation; wavelets; discrete wavelet transform; radio channel; fading; diversity; wireless systems
• Language: croatian
• URN:NBN: urn:nbn:hr:168:308298
• Study programme: Title: Doctoral study programme "Electrical Engineering and Computing"; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, po-dručje tehničkih znanosti (doktor/doktorica znanosti, po-dručje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-06-26 10:57:10