Signal processing algorithms in multicarrier systems

doctoral thesis

• Title (croatian): Algoritmi obradbe signala u sustavima s više nosilaca
• Author: Maja Slišković
• Mentor: Branko Jeren (mentor)
• Committee member: Hrvoje Babić (član povjerenstva)
• Committee member: Branko Jeren (član povjerenstva)
• Committee member: Klaus Dostert (član povjerenstva)
• Committee member: Mladen Kos (član povjerenstva)
• Committee member: Borivoj Modlic (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Electronic Systems and Information Processing); Zagreb
• Defense date and country: 2001-03-26, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

Multicarrier modulation is a technique in which a spectrally shaped channel with colored noise is partitioned into a set of parallel orthogonal subchannels, each with its own carrier. The work presented in this dissertation focuses on multicarrier systems whose basis vectors are inverse discrete Fourier transform and discrete Fourier transform vectors. To be able to reliably transmit and receive digital data at the highest possible data rate, every component of the communication system must be optimized. This dissertation addresses the following problems: optimal energy allocation (the bit-loading problem), frequency error estimation and correction, and impulse noise cancellation. A number of practical bit-loading algorithms designed for communication systems with power spectral density constraint are proposed and analyzed. Special attention is given to the problem of noise margin maximization with power spectral density constraint and bit rate constraint. A major drawback of multicarrier systems is their sensitivity to synchronization errors. The influence of sampling frequency offset is discussed and methods for its estimation and correction are proposed. A novel sampling frequency offset correction structure is developed, which interpolates the twiddle factors instead of input samples. Impulse noise is known to be highly damaging to the performance of a multicarrier system. In this dissertation, a selection of impulse noise detection algorithms is presented, and their performance is investigated. Consequently, a novel impulse noise cancellation algorithm that combines time-domain and frequency-domain analysis is proposed. Finally, computationally efficient receiver structures, for systems employing modified frequency hopping modulation are presented.

Abstract (croatian)

Modulacija s više nosilaca (engl. multicarrier modulation) dijeli spektralno oblikovani kanal s obojenim šumom na skup paralelnih ortogonalnih podkanala. U disertaciji su opisani algoritmi obradbe signala u sustavima s više nosilaca čiji su bazni vektori inverzna diskretna Fourier-ova transformacija i diskretna Fourier-ova transformacija. Da bi se postigla što veća brzina komunikacija uz zadanu pouzdanost, potrebno je optimizirati svaku komponentu komunikacijskog sustava. U disertaciji su opisana rješenja za optimalnu raspodjelu energije na pojedine nosioce, procjenu i korekciju greške frekvencije otipkavanja, te poništavanje impulsnog šuma. Predloženo je i analizirano više algoritama za optimalnu raspodjelu energije unutar zadanog frekvencijskog pojasa, uz uvjet ograničenja spektralne gustoće snage. Jedan od principijelnih nedostataka sustava s više nosilaca je osjetljivost na greške sinkronizacije u vremenskoj i frekvencijskoj domeni. U radu je analiziran utjecaj greške frekvencije otipkavanja, te su predložene metode procjene greške i algoritam korekcije. Predloženi algoritam interpolira koeficijente Fourier-ove transformacije, a ne uzorke signala, čime je postignuta veća točnost i brzina algoritma. Impulsni šum može značajno smanjiti pouzdanost prijenosa podataka u sustavima s više nosilaca. U radu je opisano više algoritama za detekciju impulsnog šuma. Informaciju o prisustvu impulsnog šuma unutar simbola mogu iskoristiti dekoder, svi adaptivni elementi prijemnika (izbjegavanje adaptiranja parametara za simbol kontaminiran impulsnim šumom), te element za poništavanje impulsnog šuma. Predložen je novi algoritam poništavanja impulsnog šuma koji kombinira analizu u vremenskoj i frekvencijskoj domeni. Također je opisana realizacija prijemnika za sustav koji koristi modulaciju modificiranog frekvencijskog skakanja, a koja se također može smatrati modulacijom s više nosilaca.

• Keywords: Multicarrier modulation; bit-loading algorithm; sampling frequency offset estimation and correction; impulse noise detection and cancellation
• Keywords (croatian): Modulacija s više nosilaca; spektralna raspodjela energije; procjena i korekcija greške frekvencije otipkavanja; detekcija i poništavanje impulsnog šuma
• Language: english
• URN:NBN: urn:nbn:hr:168:881609
• 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: 2019-04-16 08:46:54