Title :
Mitigation of intercarrier interference in OFDM systems over slow fading channels based on the EM algorithm
Author :
Vizziello, Anna ; Savazzi, Pietro ; Favalli, Lorenzo
Author_Institution :
Dipt. di Elettron., Univ. degli Studi di Pavia, Pavia, Italy
Abstract :
Orthogonal Frequency Division Multiplexing (OFDM) is a transmission technique that allows simple multipath channel equalization schemes. On the other side it is sensitive to frequency offset at the local oscillator, phase noise and Doppler shift which may destroy the orthogonality among subcarriers causing Inter Carrier Interference (ICI). It is possible to represent this interference in the frequency domain by means of an ICI matrix. Since these types of errors greatly affect the performance of an OFDM system, estimation of this matrix is crucial. In this work we propose an iterative method to mitigate the interference among subcarriers exploiting the presence of pilot tones in the frequency domain. It can be explained referring to the Expectation-Maximization (EM) paradigm. The proposed technique is very effective in multipath fading channels and a simplified version is also introduced in case of AWGN channel with frequency offset at the local oscillator. Simulation results show that the presented algorithm converges very quickly and looks promising to be used in actual implementations.
Keywords :
AWGN channels; Doppler shift; OFDM modulation; expectation-maximisation algorithm; fading channels; intercarrier interference; multipath channels; oscillators; phase noise; AWGN channel; Doppler shift; EM algorithm; OFDM systems; expectation-maximization; inter carrier interference; intercarrier interference mitigation; iterative method; multipath channel equalization; orthogonal frequency division multiplexing; oscillator; phase noise; slow fading channels; subcarriers; AWGN channels; Doppler shift; Fading; Frequency domain analysis; Interference; Iterative methods; Local oscillators; Multipath channels; OFDM; Phase noise; EM; ICI; MMSE; channel estimation; frequency offset;
Conference_Titel :
MELECON 2010 - 2010 15th IEEE Mediterranean Electrotechnical Conference
Conference_Location :
Valletta
Print_ISBN :
978-1-4244-5793-9
DOI :
10.1109/MELCON.2010.5475972