Self-Cancellation of Intercarrier Interference in OFDM Systems with Phase Noise

Instability of the local oscillator causes phase noise – a phenomenon that is a disadvantage and is considered to be a major obstacle in the functioning of coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. An attempt has been made in this paper to reduce the eﬀects of common phase errors generated by phase noise. In this paper, a least mean square (LMS) based algorithm is proposed for estimation of phase noise. Using this proposed algorithm, the major problem of phase ambiguity caused by cycle slip is avoided and the bit error rate is greatly improved. Further, there is no requirement for modifying the frame structure of OFDM using this algorithm. A CO-OFDM system with the 8-PSK technique is used to implement the algorithm concerned. Furthermore, the algorithm, using the 8-PSK modulation technique, is analyzed and compared with the existing QPSK technique and with other algorithms. The investigations reveal that 8-PSK outperforms existing LMS algorithms using other techniques and signiﬁcantly reduces the bit error rate.

Download Full-text

A Radon Slantlet Transforms Based OFDM System Design and Performance Simulation under Different Channel Conditions

ISRN Communications and Networking ◽

10.5402/2012/318921 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Abbas Hasan Kattoush

Keyword(s):

Radon Transform ◽

Spectral Efficiency ◽

Fading Channel ◽

Orthogonal Frequency Division Multiplexing ◽

Additive White Gaussian Noise ◽

Mapping Technique ◽

Intercarrier Interference ◽

Ofdm Systems ◽

Ofdm System ◽

Channel Parameters

Due to its good orthogonality, slantlet transform (SLT) is used in orthogonal frequency division multiplexing (OFDM) systems to reduce intersymbol interference (ISI) and intercarrier interference (ICI). This eliminates the need for cyclic prefix (CP) and increases the spectral efficiency of the design. Finite Radon transform (FRAT) mapper has the ability to increase orthogonality of subcarriers, is nonsensitive to channel parameters variations, and has a small constellation energy compared with conventional fast-Fourier-transform- (FFT-) based OFDM. It is also able to work as a good interleaver, which significantly reduces the bit error rate (BER). In this paper both FRAT mapping technique and SLT modulator are implemented in a new design of an OFDM system. The new structure was tested and compared with conventional FFT-based OFDM, Radon transform-based OFDM, and SLT-based OFDM for additive white Gaussian noise (AWGN) channel, flat fading channel (FFC), and multipath selective fading channel (SFC). Simulation tests were generated for different channel parameters values. The obtained results showed that the proposed system has increased the spectral efficiency, reduced ISI and ICI, and improved BER performance compared with other systems.

Download Full-text

Common Magnitude Error Due to Phase Noise in OFDM Systems

2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications ◽

10.1109/pimrc.2007.4394322 ◽

2007 ◽

Author(s):

Sean Lawrence ◽

Ashim Biswas ◽

Anees Sahib

Keyword(s):

Phase Noise ◽

Ofdm Systems

Download Full-text