Abstract:
Orthogonal frequency-division multiplexing (OFDM) is robust against frequency selective fading due to the increase of the symbol duration. However, for mobile application...Show MoreMetadata
Abstract:
Orthogonal frequency-division multiplexing (OFDM) is robust against frequency selective fading due to the increase of the symbol duration. However, for mobile applications channel time-variations in one OFDM symbol introduce intercarrier-interference (ICI) which degrades the performance. This becomes more severe as mobile speed, carrier frequency or OFDM symbol duration increases. As delay spread increases, symbol duration should also increase in order to maintain a near-constant channel in every frequency subband. Also, due to the high demand for bandwidth, there is a trend toward higher carrier frequencies. Therefore, to have an acceptable reception quality for the applications that experience high delay and Doppler spread, there is a need for ICI mitigation within one OFDM symbol. We introduce two new methods to mitigate ICI in an OFDM system with coherent channel estimation. Both methods use a piece-wise linear model to approximate channel time-variations. The first method extracts channel time-variations information from the cyclic prefix. The second method estimates these variations using the next symbol. We find a closed-form expression for the improvement in average signal-to-interference ratio (SIR) when our mitigation methods are applied for a narrowband time-variant channel. Finally, our simulation results show how these methods would improve the performance in a highly time-variant environment with high delay spread.
Published in: IEEE Transactions on Wireless Communications ( Volume: 4, Issue: 2, March 2005)
Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA
Yasamin Mostofi (S'98–M'04) received the B.S. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 1997, and the M.S. and Ph.D. degrees from Stanford University, Stanford, CA, in 1999 and 2003, respectively.
She has worked on several aspects of wireless communications for Lucent Technologies–Bell Labs, Murray Hills, NJ, in 1999 and National Semiconductor, Fremont, CA, in 2002. Since Janua...Show More
Yasamin Mostofi (S'98–M'04) received the B.S. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 1997, and the M.S. and Ph.D. degrees from Stanford University, Stanford, CA, in 1999 and 2003, respectively.
She has worked on several aspects of wireless communications for Lucent Technologies–Bell Labs, Murray Hills, NJ, in 1999 and National Semiconductor, Fremont, CA, in 2002. Since Janua...View more
Department of Electrical Engineering, University of Stanford, Stanford, CA, USA
Donald C. Cox (M'61–SM'72–F'79) received the B.S. and M.S. degrees in electrical engineering from the University of Nebraska, Lincoln, in 1959 and 1960, respectively, and the Ph.D. degree in electrical engineering from Stanford University, Stanford, CA, in 1968. He received an Honorary Dr. Sci. degree from the University of Nebraska in 1983.
From 1960 to 1963, he was with Wright-Patterson AFB, OH, where he reasearched micr...Show More
Donald C. Cox (M'61–SM'72–F'79) received the B.S. and M.S. degrees in electrical engineering from the University of Nebraska, Lincoln, in 1959 and 1960, respectively, and the Ph.D. degree in electrical engineering from Stanford University, Stanford, CA, in 1968. He received an Honorary Dr. Sci. degree from the University of Nebraska in 1983.
From 1960 to 1963, he was with Wright-Patterson AFB, OH, where he reasearched micr...View more
Contents Department of Electrical Engineering, California Institute of Technology, Pasadena, CA, USA
Yasamin Mostofi (S'98–M'04) received the B.S. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 1997, and the M.S. and Ph.D. degrees from Stanford University, Stanford, CA, in 1999 and 2003, respectively.
She has worked on several aspects of wireless communications for Lucent Technologies–Bell Labs, Murray Hills, NJ, in 1999 and National Semiconductor, Fremont, CA, in 2002. Since January 2004, she has been a Postdoctoral Scholar with the California Institute of Technology, Pasadena. Her research interests include mobile communications, sensor networks, cross-layer designs, and advanced signal processing.
Yasamin Mostofi (S'98–M'04) received the B.S. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 1997, and the M.S. and Ph.D. degrees from Stanford University, Stanford, CA, in 1999 and 2003, respectively.
She has worked on several aspects of wireless communications for Lucent Technologies–Bell Labs, Murray Hills, NJ, in 1999 and National Semiconductor, Fremont, CA, in 2002. Since January 2004, she has been a Postdoctoral Scholar with the California Institute of Technology, Pasadena. Her research interests include mobile communications, sensor networks, cross-layer designs, and advanced signal processing.View more
Department of Electrical Engineering, University of Stanford, Stanford, CA, USA
Donald C. Cox (M'61–SM'72–F'79) received the B.S. and M.S. degrees in electrical engineering from the University of Nebraska, Lincoln, in 1959 and 1960, respectively, and the Ph.D. degree in electrical engineering from Stanford University, Stanford, CA, in 1968. He received an Honorary Dr. Sci. degree from the University of Nebraska in 1983.
From 1960 to 1963, he was with Wright-Patterson AFB, OH, where he reasearched microwave communications system design. From 1963 to 1968, he was with Stanford University researching tunnel diode amplifier design and research on microwave propagation in the troposphere. From 1968 to 1973, his research at Bell Laboratories, Holmdel, NJ, in mobile radio propagation and on high-capacity mobile radio systems provided important input to early cellular mobile radio system development, and is continuing to contribute to the evolution of digital cellular radio, wireless personal communications systems, and cordless telephones. From 1973 to 1983, he was Supervisor of a group at Bell Laboratories that did innovative propagation and system research for millimeter-wave satellite communications. In 1978, he pioneered radio system and propagation research for low-power wireless personal communications systems. At Bell Laboratories in 1983, he organized and became Head of the Radio and Satellite Systems Research Department that became a Division in Bell Communications Research (Bellcore) with the breakup of the Bell System on January 1, 1984. He was Division Manager of the Radio Research Division until it again became a department in 1991. He continued as Executive Director of the Radio Research Department where he championed, led, and contributed to research on all aspects of low-power wireless personal communications entitled Universal Digital Portable Communications (UDPC). He was instrumental in evolving the extensive research results into specifications that became the U.S. Standard for the Wireless or Personal Access Communications System (WACS or PACS). In September 1993, he became a Professor of Electrical Engineering and Director of the Center for Telecommunications, Stanford University, where he continues to pursue research and teaching of wireless mobile and personal communications. He was appointed Harald Trap Friis Professor of Engineering at Stanford in 1994. He is author or coauthor of many papers and conference presentations, including many invited and several keynote addresses, and books. He has been granted 15 patents.
Dr. Cox was a member of the Administrative Committee of the IEEE Antennas and Propagation Society (1986–1988), and was an Associate Editor of the IEEE Transactions on Antennas and Propagation (1983–1986). He received the 1983 IEEE Vehicular Technology Society Paper of the Year Award, the IEEE 1985 Morris E. Leeds Award, the 1990 Communications Magazine Prize Paper Award, the IEEE Communications Society 1992 L. G. Abraham Prize Paper Award, the IEEE 1993 Alexander Graham Bell Medal “for pioneering and leadership in personal portable communications,” and the IEEE Third Millennium Medal in 2000. He was also a corecipient of the 1983 International Marconi Prize in Electromagnetic Wave Propagation (Italy), and received the Bellcore Fellow Award in 1991. He is a Fellow of AAAS and the Radio Club of America and a member of the National Academy of Engineering, Commissions B, C and F of USNC/URSI, Sigma Xi, Sigma Tau, Eta Kappa Nu, and Phi Mu Epsilon. He was a member of the URSI Intercommission Group on Time Domain Waveform Measurements from 1982 to 1984. He is a Registered Professional Engineer in Ohio and Nebraska.
Donald C. Cox (M'61–SM'72–F'79) received the B.S. and M.S. degrees in electrical engineering from the University of Nebraska, Lincoln, in 1959 and 1960, respectively, and the Ph.D. degree in electrical engineering from Stanford University, Stanford, CA, in 1968. He received an Honorary Dr. Sci. degree from the University of Nebraska in 1983.
From 1960 to 1963, he was with Wright-Patterson AFB, OH, where he reasearched microwave communications system design. From 1963 to 1968, he was with Stanford University researching tunnel diode amplifier design and research on microwave propagation in the troposphere. From 1968 to 1973, his research at Bell Laboratories, Holmdel, NJ, in mobile radio propagation and on high-capacity mobile radio systems provided important input to early cellular mobile radio system development, and is continuing to contribute to the evolution of digital cellular radio, wireless personal communications systems, and cordless telephones. From 1973 to 1983, he was Supervisor of a group at Bell Laboratories that did innovative propagation and system research for millimeter-wave satellite communications. In 1978, he pioneered radio system and propagation research for low-power wireless personal communications systems. At Bell Laboratories in 1983, he organized and became Head of the Radio and Satellite Systems Research Department that became a Division in Bell Communications Research (Bellcore) with the breakup of the Bell System on January 1, 1984. He was Division Manager of the Radio Research Division until it again became a department in 1991. He continued as Executive Director of the Radio Research Department where he championed, led, and contributed to research on all aspects of low-power wireless personal communications entitled Universal Digital Portable Communications (UDPC). He was instrumental in evolving the extensive research results into specifications that became the U.S. Standard for the Wireless or Personal Access Communications System (WACS or PACS). In September 1993, he became a Professor of Electrical Engineering and Director of the Center for Telecommunications, Stanford University, where he continues to pursue research and teaching of wireless mobile and personal communications. He was appointed Harald Trap Friis Professor of Engineering at Stanford in 1994. He is author or coauthor of many papers and conference presentations, including many invited and several keynote addresses, and books. He has been granted 15 patents.
Dr. Cox was a member of the Administrative Committee of the IEEE Antennas and Propagation Society (1986–1988), and was an Associate Editor of the IEEE Transactions on Antennas and Propagation (1983–1986). He received the 1983 IEEE Vehicular Technology Society Paper of the Year Award, the IEEE 1985 Morris E. Leeds Award, the 1990 Communications Magazine Prize Paper Award, the IEEE Communications Society 1992 L. G. Abraham Prize Paper Award, the IEEE 1993 Alexander Graham Bell Medal “for pioneering and leadership in personal portable communications,” and the IEEE Third Millennium Medal in 2000. He was also a corecipient of the 1983 International Marconi Prize in Electromagnetic Wave Propagation (Italy), and received the Bellcore Fellow Award in 1991. He is a Fellow of AAAS and the Radio Club of America and a member of the National Academy of Engineering, Commissions B, C and F of USNC/URSI, Sigma Xi, Sigma Tau, Eta Kappa Nu, and Phi Mu Epsilon. He was a member of the URSI Intercommission Group on Time Domain Waveform Measurements from 1982 to 1984. He is a Registered Professional Engineer in Ohio and Nebraska.View more
