The Experts below are selected from a list of 5475 Experts worldwide ranked by ideXlab platform
Seemay Phoong - One of the best experts on this subject based on the ideXlab platform.
-
A filterbank approach to window designs for multicarrier systems
IEEE Circuits and Systems Magazine, 2007Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:Windowing is often applied to multicarrier systems to improve frequency separation among the subcarriers. At the transmitter side better frequency separation leads to a smaller out-of-band Spectral Leakage and also less interference to radio frequency transmission. At the receiver side better separation gives more suppression of radio frequency interference. As these are frequency based characteristics, a filterbank representation presents a natural and useful framework for formulating the problem. In this work, we propose a unified filterbank approach to the design of windows for multicarrier systems. The filterbank viewpoint provides an additional insight into the transmitter design for Spectral Leakage reduction as well as to the receiver design for interference suppression. A better frequency separation among the subchannels can be achieved.
-
Window designs for DFT-based multicarrier systems
IEEE Transactions on Signal Processing, 2005Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:We consider window designs for discrete Fourier transform (DFT) based multicarrier transceivers without using extra cyclic prefix. As in previous works of window designs for DFT-based transceivers, a postprocessing matrix that is generally channel dependent, is needed to have a zero-forcing receiver. We show that postprocessing is channel independent if and only if the window itself has the cyclic-prefixed property. We design optimal windows with minimum Spectral Leakage subject to the cyclic-prefixed condition. Moreover, we analyze how postprocessing affects the signal-to-noise ratio (SNR) at the receiver, which is an aspect that is not considered in most of the earlier works. The resulting SNR can be given in a closed form. Join optimization of Spectral Leakage and SNR are also considered. Furthermore, examples demonstrate that we can have a significant reduction in Spectral Leakage at the cost of a small SNR loss. In addition to cyclic-prefixed systems, window designs for zero-padded DFT-based transceivers are considered. For the zero-padded transceivers, windows that minimize Spectral Leakage can also be designed.
-
windowed multicarrier systems with minimum Spectral Leakage
International Conference on Acoustics Speech and Signal Processing, 2004Co-Authors: Yuanpei Lin, Yungyih Ban, Seemay PhoongAbstract:The transmitter output of OFDM or DMT systems with a rectangular window is known to have large Spectral sidelobes. Windowing and pulse shaping have been proposed to reduce Spectral Leakage in the literature. If no extra cyclic prefix is available, windowing at the transmitter requires additional post-processing equalization at the receiver. In this paper, we design optimal windows with minimum Spectral Leakage. Moreover, we show that the post processing affects the SNR at the receiver and the resulting SNR can be given in a closed form. Furthermore, we demonstrate that we can have a good trade-off between SNR and Spectral Leakage.
-
ICASSP (4) - Windowed multicarrier systems with minimum Spectral Leakage
2004 IEEE International Conference on Acoustics Speech and Signal Processing, 1Co-Authors: Yuanpei Lin, Yungyih Ban, Seemay PhoongAbstract:The transmitter output of OFDM or DMT systems with a rectangular window is known to have large Spectral sidelobes. Windowing and pulse shaping have been proposed to reduce Spectral Leakage in the literature. If no extra cyclic prefix is available, windowing at the transmitter requires additional post-processing equalization at the receiver. In this paper, we design optimal windows with minimum Spectral Leakage. Moreover, we show that the post processing affects the SNR at the receiver and the resulting SNR can be given in a closed form. Furthermore, we demonstrate that we can have a good trade-off between SNR and Spectral Leakage.
-
ISCC - DFT based transceivers with-windowing
Proceedings. ISCC 2004. Ninth International Symposium on Computers And Communications (IEEE Cat. No.04TH8769), 1Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:In this paper we consider window designs for DFT (discrete Fourier transform) based multicarrier transceivers without using extra cyclic prefix. As in previous works of window designs for DFT based transceiver, a post processing matrix, generally channel dependent, is needed to have a zero forcing receiver. We show that post processing is channel independent if and only if the window itself has the cyclic prefixed property. We design optimal windows with minimum Spectral Leakage subject to the cyclic-prefixed condition. Moreover, we analyze how post processing affects SNR (signal to noise ratio) at the receiver, an aspect that is hot considered in most of the earlier works. The resulting SNR can be given in a closed form. Join optimization of Spectral Leakage and SNR are also considered. Furthermore, examples demonstrate that we can have a significant reduction in Spectral Leakage at the cost of a small SNR penalty.
Márcio Flávio Dutra Moraes - One of the best experts on this subject based on the ideXlab platform.
-
Post-processing of auditory steady-state responses to correct Spectral Leakage
Journal of neuroscience methods, 2009Co-Authors: Leonardo Bonato Felix, Eduardo M. A. M. Mendes, Márcio Flávio Dutra MoraesAbstract:Auditory steady-state responses (ASSRs) are electrical manifestations of brain due to high rate sound stimulation. These evoked responses can be used to assess the hearing capabilities of a subject in an objective, automatic fashion. Usually, the detection protocol is accomplished by frequency-domain techniques, such as magnitude-squared coherence, whose estimation is based on the fast Fourier transform (FFT) of several data segments. In practice, the FFT-based spectrum may spread out the energy of a given frequency to its side bins and this escape of energy in the spectrum is called Spectral Leakage. The distortion of the spectrum due to Leakage may severely compromise statistical significance of objective detection. This work presents an offline, a posteriori method for Spectral Leakage minimization in the frequency-domain analysis of ASSRs using coherent sampling criterion and interpolation in time. The technique was applied to the local field potentials of 10 Wistar rats and the results, together with those from simulated data, indicate that a Leakage-free analysis of ASSRs is possible for any dataset if the methods showed in this paper were followed.
-
Avoiding Spectral Leakage in objective detection of auditory steady-state evoked responses in the inferior colliculus of rat using coherence.
Journal of neuroscience methods, 2005Co-Authors: Leonardo Bonato Felix, José Elvano Moraes, Hani Camille Yehia, Márcio Flávio Dutra MoraesAbstract:Local field potentials (LFP) are bioelectric signals recorded from the brain that reflect neural activity in a high temporal resolution. Separating background activity from that evoked by specific somato-sensory input is a matter of great clinical relevance in neurology. The coherence function is a Spectral coefficient that can be used as a detector of periodic responses in noisy environments. Auditory steady-state responses to amplitude-modulated tones generate periodic responses in neural networks that may be accessed by means of coherence between the stimulation signal and the LFP recorded from the auditory pathway. Such signal processing methodology was applied in this work to evaluate in vivo, anaesthetized Wistar rats, activation of neural networks due to single carrier sound stimulation frequencies, as well as to evaluate the effect of different modulating tones in the evoked responses. Our results show that an inappropriate choice of sound stimuli modulating frequencies can compromise coherence analysis, e.g. misleading conclusions due to mathematical artefact of signal processing. Two modulating frequency correction protocols were used: nearest integer and nearest prime number. The nearest prime number correction was successful in avoiding Spectral Leakage in the coherence analysis of steady-state auditory response, as predicted by Monte Carlo simulations.
Thinh Hung Pham - One of the best experts on this subject based on the ideXlab platform.
-
An efficient Spectral Leakage filtering for IEEE 802.11af in TV white space
2018 2nd International Conference on Recent Advances in Signal Processing Telecommunications & Computing (SigTelCom), 2018Co-Authors: Phu X. V. Nguyen, Thinh Hung Pham, Trang Hoang, Oh-soon ShinAbstract:Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant Spectral Leakage due to the accumulation of multiple siwc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient Spectral Leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce Spectral Leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ESI), resulting in a loss of Spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better Spectral Leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters.
-
An Efficient Spectral Leakage Filtering for IEEE 802.11af in TV White Space
arXiv: Signal Processing, 2017Co-Authors: Phu X. V. Nguyen, Thinh Hung Pham, Trang Hoang, Oh-soon ShinAbstract:Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant Spectral Leakage due to the accumulation of multiple sinc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient Spectral Leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce Spectral Leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ISI), resulting in a loss of Spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better Spectral Leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters.
-
VTC Spring - Shaping Spectral Leakage for IEEE 802.11p Vehicular Communications
2014 IEEE 79th Vehicular Technology Conference (VTC Spring), 2014Co-Authors: Thinh Hung Pham, Ian Mcloughlin, Suhaib A. FahmyAbstract:IEEE 802.11p is a recently defined standard for the physical (PHY) and medium access control (MAC) layers for Dedicated Short-Range Communications. Four Spectrum Emission Masks (SEMs) are specified in 802.11p that are much more stringent than those for current 802.11 systems. In addition, the guard interval in 802.11p has been lengthened by reducing the bandwidth to support vehicular communication (VC) channels, and this results in a narrowing of the frequency guard. This raises a significant challenge for filtering the spectrum of 802.11p signals to meet the specifications of the SEMs. We investigate state of the art pulse shaping and filtering techniques for 802.11p, before proposing a new method of shaping the 802.11p Spectral Leakage to meet the most stringent, class D, SEM specification. The proposed method, performed at baseband to relax the strict constraints of the radio frequency (RF) front-end, allows 802.11p systems to be implemented using commercial off-the-shelf (COTS) 802.11a RF hardware, resulting in reduced total system cost.
Oh-soon Shin - One of the best experts on this subject based on the ideXlab platform.
-
An efficient Spectral Leakage filtering for IEEE 802.11af in TV white space
2018 2nd International Conference on Recent Advances in Signal Processing Telecommunications & Computing (SigTelCom), 2018Co-Authors: Phu X. V. Nguyen, Thinh Hung Pham, Trang Hoang, Oh-soon ShinAbstract:Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant Spectral Leakage due to the accumulation of multiple siwc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient Spectral Leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce Spectral Leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ESI), resulting in a loss of Spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better Spectral Leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters.
-
An Efficient Spectral Leakage Filtering for IEEE 802.11af in TV White Space
arXiv: Signal Processing, 2017Co-Authors: Phu X. V. Nguyen, Thinh Hung Pham, Trang Hoang, Oh-soon ShinAbstract:Orthogonal frequency division multiplexing (OFDM) has been widely adopted for modern wireless standards and become a key enabling technology for cognitive radios. However, one of its main drawbacks is significant Spectral Leakage due to the accumulation of multiple sinc-shaped subcarriers. In this paper, we present a novel pulse shaping scheme for efficient Spectral Leakage suppression in OFDM based physical layer of IEEE 802.11af standard. With conventional pulse shaping filters such as a raised-cosine filter, vestigial symmetry can be used to reduce Spectral Leakage very effectively. However, these pulse shaping filters require long guard interval, i.e., cyclic prefix in an OFDM system, to avoid inter-symbol interference (ISI), resulting in a loss of Spectral efficiency. The proposed pulse shaping method based on asymmetric pulse shaping achieves better Spectral Leakage suppression and decreases ISI caused by filtering as compared to conventional pulse shaping filters.
Yuanpei Lin - One of the best experts on this subject based on the ideXlab platform.
-
A filterbank approach to window designs for multicarrier systems
IEEE Circuits and Systems Magazine, 2007Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:Windowing is often applied to multicarrier systems to improve frequency separation among the subcarriers. At the transmitter side better frequency separation leads to a smaller out-of-band Spectral Leakage and also less interference to radio frequency transmission. At the receiver side better separation gives more suppression of radio frequency interference. As these are frequency based characteristics, a filterbank representation presents a natural and useful framework for formulating the problem. In this work, we propose a unified filterbank approach to the design of windows for multicarrier systems. The filterbank viewpoint provides an additional insight into the transmitter design for Spectral Leakage reduction as well as to the receiver design for interference suppression. A better frequency separation among the subchannels can be achieved.
-
Window designs for DFT-based multicarrier systems
IEEE Transactions on Signal Processing, 2005Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:We consider window designs for discrete Fourier transform (DFT) based multicarrier transceivers without using extra cyclic prefix. As in previous works of window designs for DFT-based transceivers, a postprocessing matrix that is generally channel dependent, is needed to have a zero-forcing receiver. We show that postprocessing is channel independent if and only if the window itself has the cyclic-prefixed property. We design optimal windows with minimum Spectral Leakage subject to the cyclic-prefixed condition. Moreover, we analyze how postprocessing affects the signal-to-noise ratio (SNR) at the receiver, which is an aspect that is not considered in most of the earlier works. The resulting SNR can be given in a closed form. Join optimization of Spectral Leakage and SNR are also considered. Furthermore, examples demonstrate that we can have a significant reduction in Spectral Leakage at the cost of a small SNR loss. In addition to cyclic-prefixed systems, window designs for zero-padded DFT-based transceivers are considered. For the zero-padded transceivers, windows that minimize Spectral Leakage can also be designed.
-
windowed multicarrier systems with minimum Spectral Leakage
International Conference on Acoustics Speech and Signal Processing, 2004Co-Authors: Yuanpei Lin, Yungyih Ban, Seemay PhoongAbstract:The transmitter output of OFDM or DMT systems with a rectangular window is known to have large Spectral sidelobes. Windowing and pulse shaping have been proposed to reduce Spectral Leakage in the literature. If no extra cyclic prefix is available, windowing at the transmitter requires additional post-processing equalization at the receiver. In this paper, we design optimal windows with minimum Spectral Leakage. Moreover, we show that the post processing affects the SNR at the receiver and the resulting SNR can be given in a closed form. Furthermore, we demonstrate that we can have a good trade-off between SNR and Spectral Leakage.
-
ICASSP (4) - Windowed multicarrier systems with minimum Spectral Leakage
2004 IEEE International Conference on Acoustics Speech and Signal Processing, 1Co-Authors: Yuanpei Lin, Yungyih Ban, Seemay PhoongAbstract:The transmitter output of OFDM or DMT systems with a rectangular window is known to have large Spectral sidelobes. Windowing and pulse shaping have been proposed to reduce Spectral Leakage in the literature. If no extra cyclic prefix is available, windowing at the transmitter requires additional post-processing equalization at the receiver. In this paper, we design optimal windows with minimum Spectral Leakage. Moreover, we show that the post processing affects the SNR at the receiver and the resulting SNR can be given in a closed form. Furthermore, we demonstrate that we can have a good trade-off between SNR and Spectral Leakage.
-
ISCC - DFT based transceivers with-windowing
Proceedings. ISCC 2004. Ninth International Symposium on Computers And Communications (IEEE Cat. No.04TH8769), 1Co-Authors: Yuanpei Lin, Seemay PhoongAbstract:In this paper we consider window designs for DFT (discrete Fourier transform) based multicarrier transceivers without using extra cyclic prefix. As in previous works of window designs for DFT based transceiver, a post processing matrix, generally channel dependent, is needed to have a zero forcing receiver. We show that post processing is channel independent if and only if the window itself has the cyclic prefixed property. We design optimal windows with minimum Spectral Leakage subject to the cyclic-prefixed condition. Moreover, we analyze how post processing affects SNR (signal to noise ratio) at the receiver, an aspect that is hot considered in most of the earlier works. The resulting SNR can be given in a closed form. Join optimization of Spectral Leakage and SNR are also considered. Furthermore, examples demonstrate that we can have a significant reduction in Spectral Leakage at the cost of a small SNR penalty.
