Performance degradation of OFDM systems due to Doppler spreading

• Published in: IEEE transactions on wireless communications Vol. 5; no. 6; pp. 1422 - 1432
• Main Authors: Tiejun Wang, Proakis, J.G., Masry, E., Zeidler, J.R.
• Format: Journal Article
• Language: English
• Published: Piscataway, NJ IEEE 01-06-2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Channels; Degradation; Digital video broadcasting; Doppler effect; Error probability; Errors; Exact sciences and technology; Gaussian; Information, signal and communications theory; Land mobile radio; Mathematical models; Modulation; Multiplexing; OFDM modulation; Orthogonal Frequency Division Multiplexing; Phase modulation; Phase shift keying; Probability density functions; Quadrature amplitude modulation; Rayleigh channels; RF signals; Signal and communications theory; Studies; Subcarriers; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Fading channels; Performance evaluation; Error probability; OFDM; Wireless telecommunication; Intercarrier interference; two-dimensional Gram-Charlier series; Doppler effect; ICI; Doppler spreading; Orthogonal frequency division multiplexing; Gaussian mixture; Rayleigh fading; C/I ratio
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2006.1638663

The focus of this paper is on the performance of orthogonal frequency division multiplexing (OFDM) signals in mobile radio applications, such as 802.11a and digital video broadcasting (DVB) systems, e.g., DVB-CS2. The paper considers the evaluation of the error probability of an OFDM system transmitting over channels characterized by frequency selectivity and Rayleigh fading. The time variations of the channel during one OFDM symbol interval destroy the orthogonality of the different subcarriers and generate power leakage among the subcarriers, known as inter-carrier interference (ICI). For conventional modulation methods such as phase-shift keying (PSK) and quadrature-amplitude modulation (QAM), the bivariate probability density function (pdf) of the ICI is shown to be a weighted Gaussian mixture. The large computational complexity involved in using the weighted Gaussian mixture pdf to evaluate the error probability serves as the motivation for developing a two-dimensional Gram-Charlier representation for the bivariate pdf of the ICI. It is demonstrated that its truncated version of order 4 or 6 provides a very good approximation in the evaluation of the error probability for PSK and QAM in the presence of ICI. Based on Jakes' model for the Doppler effects, and an exponential multipath intensity profile, numerical results for the error probability are illustrated for several mobile speeds