Procjena vremenskog pomaka simbola u OFDM sustavima

master's thesis

• Title (english): Estimation of symbol timing offset in OFDM systems
• Author: Ivan Čavlek
• Mentor: Sonja Grgić (mentor)
• Committee member: Sonja Grgić (predsjednik povjerenstva)
• Committee member: Tomislav Kos (član povjerenstva)
• Committee member: Mislav Grgić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; Zagreb
• Defense date and country: 2023-07-04, Croatia

Abstract

U ovom radu sinkronizacijske tehnike koje koriste zaštitni interval (eng. Cyclic Prefix - CP) su analizirane, s ciljem ukljanjanja utjecaja vremenskog pomaka simbola (eng. Symbol Time Offset - STO ) za ispravnu sinkronizaciju u frekvencijskom multipleksu ortogonalnih podnosioca (eng. Orthogonal Frequency Division Multiplex - OFDM). OFDM je robusna i učinkovita sinkronizacijska tehnika korištena u bežičnim komunikacijama, stoga je vrlo važno provesti postupak sinkronizacije radi ispravne demodulacije. Za točnu procjenu STO-a koristeći CP rabe se dvije tehnike. Prva se bazira na pronalasku maksimalne korelacije između dva bloka, a druga na pronalasku sličnosti između dva bloka, koja je maksimalna kada je razlika između njih minimalna. Promatraju se dva slučaja. Prvi je slučaj samo s bijelim Gaussovim šumom, a u drugom se koristi i impulsni odziv Rayleighevog kanala. Kada su nadodani efekti kanala, performanse obiju estimacija (korelacije i diferencije) budu degradirane ako nije osigurana dovoljna razina odnosa signal-šum i odgovarajuća duljina CP-a.

Abstract (english)

In this paper synchronization techniques using cyclic prefix (CP) are analyzed to remove the influence of symbol time offset (STO) for correct synchronization in Orthogonal
Frequency Division Multiplex (OFDM) system. OFDM is a robust and efficient modulation technique used in wireless communications, therefore it is very important to perform a
synchronization procedure for correct demodulation. For correct detection of STO using CP
two techniques are used. The first one is based on finding the maximum correlation between
two blocks and the second one is on finding the similarity between two blocks which is
maximized when the difference between them is minimized. Two cases are observed. The
first one uses only additive white Gaussian noise (AWGN), while the second also uses the
channel impulse response (CIR) of the Rayleigh channel. When channel effect is added both
performances of estimation by correlation and difference deteriorate if a sufficient level of
signal-to-noise (SNR) and proper length of CP are not provided.

• Keywords: Sinkronizacija; OFDM; STO; Zaštitni interval
• Keywords (english): Synchronization; OFDM; STO; Cyclic Prefix
• Language: croatian
• URN:NBN: urn:nbn:hr:168:933033
• Study programme: Title: Information and Communication Technology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka informacijske i komunikacijske tehnologije (magistar/magistra inženjer/inženjerka informacijske i komunikacijske tehnologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2023-10-11 08:37:38