J. Cioffi
Stanford University, Electrical Engineering, Faculty Member
... (A-5) The overall system mean of the sub-channel SNRs defined by:[91 can be approximated by the geometric r 1 L (A-7) ... 5. PS Chow, et al., "Preliminary Feasibility Study of a Multi-Carrier Transmission System... more
... (A-5) The overall system mean of the sub-channel SNRs defined by:[91 can be approximated by the geometric r 1 L (A-7) ... 5. PS Chow, et al., "Preliminary Feasibility Study of a Multi-Carrier Transmission System for the Prqosed ADSL Data Service," TlE1.490-211. ...
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The degradation in echo canceler performance caused by frequency offset (phase roll) in the far-end echo is investigated. It is determined that even a very small nonzero frequency offset, in extreme situations of -0.01 Hz, can lead to an... more
The degradation in echo canceler performance caused by frequency offset (phase roll) in the far-end echo is investigated. It is determined that even a very small nonzero frequency offset, in extreme situations of -0.01 Hz, can lead to an acceptable degradation in the performance of the echo canceler. A method for compensating the frequency offset is also devised and recommended. The method directly estimates the offset frequency while maintaining the use of the Nyquist T/3 echo canceler. This latter feature contrasts with previous methods, which usually revert to the more computationally intensive cross-coupled echo canceler for the implementation. As acquisition of frequency offset in the presence of a strong double talker is very slow; a fast acquisition method is presumed
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We consider the problem of minimizing the outage prob-ability for data transmission in a fading channel. We con-sider a block$at fading channel, where both the transmitter and receiver have per$ect knowledge of the channel gain of the... more
We consider the problem of minimizing the outage prob-ability for data transmission in a fading channel. We con-sider a block$at fading channel, where both the transmitter and receiver have per$ect knowledge of the channel gain of the current block. The delay constraint is in the ...
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The important problem of Adaptive Line Enhancing (ALE) is addressed in this paper. Its solution involves an Adaptive Notch Filter (ANF) proposed in [1],[2] using a minimal parameter constrained infinite impulse response (IIR) model in... more
The important problem of Adaptive Line Enhancing (ALE) is addressed in this paper. Its solution involves an Adaptive Notch Filter (ANF) proposed in [1],[2] using a minimal parameter constrained infinite impulse response (IIR) model in conjunction with the Recursive Prediction Error Method (RPEM) [3]. A Fast Transversal Filter (FTF) algorithm for the adaptive RLS-type updating of the linear phase filter
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... ABSTRACT A recursive-least-squares (RLS) adaptive fast transversal filter (FIT) for processing of continuous-time signals is presented. ... The structure of our analogfast transversal filter is identical to that of the discrete-time... more
... ABSTRACT A recursive-least-squares (RLS) adaptive fast transversal filter (FIT) for processing of continuous-time signals is presented. ... The structure of our analogfast transversal filter is identical to that of the discrete-time FTF. ...
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Space-time codes have been introduced to improve a mobile system's performance in a multipath fading environment. We consider an L-multipath, m mobile-antenna system in which the base station has a phased n-antenna array (i.e. fading... more
Space-time codes have been introduced to improve a mobile system's performance in a multipath fading environment. We consider an L-multipath, m mobile-antenna system in which the base station has a phased n-antenna array (i.e. fading at the base station antennas is completely correlated). We show that when the channel has no ISI, then adaptive antennas, in the form of beamforming,
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Abstract The problem of optimizing the transmission bandwidth of practical coded-modulation transceivers on linear time-invariant (LTI) dispersive channels corrupted by additive white Gaussian noise (AWGN) and crosstalk, with particular... more
Abstract The problem of optimizing the transmission bandwidth of practical coded-modulation transceivers on linear time-invariant (LTI) dispersive channels corrupted by additive white Gaussian noise (AWGN) and crosstalk, with particular emphasis on digital ...
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Research Interests: Electronic Engineering, Computer Science, Numerical Simulation, MIMO, Noise Cancellation, and 14 moreDSL, Crosstalk, Digital Subscriber Line, Transmission Line, Conductors, Information Rate, Electric Power Transmission, Communications, Transmission Line Theory, Digital Subscriber Lines, Electrical And Electronic Engineering, Data Transmission, MIMO System, and Multiconductor Transmission Line
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It is well known that the minimum mean square error (MMSE) and minimum peak distortion (MPD) criteria do not minimize bit error rate (MinBER), and for some channels they can have a large degradation compared to the MinBER solution. Based... more
It is well known that the minimum mean square error (MMSE) and minimum peak distortion (MPD) criteria do not minimize bit error rate (MinBER), and for some channels they can have a large degradation compared to the MinBER solution. Based on the strengths and weaknesses of the MMSE and MPD criteria, we have defined two new solutions, which we call minimum noise limited peak distortion (MNLPD) and min-α. The first solution is based on MPD but avoids the problem of noise enhancement. The second solution finds the optimal of a family of equalizers derived from the MMSE and MPD criteria. We have shown by numerical calculation that by using the MNLPD or the min-α criteria we can achieve almost MinBER performance. The proposed methods have a larger complexity, but can be solved using well known techniques since they can be described as simple convex optimization problems
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In current discrete multitone (DMT) wireline modems, crosstalk interference has been the major limitation in achieving high data rates. The introduction of a crosstalker can cause such a large disturbance that the modem is not able to... more
In current discrete multitone (DMT) wireline modems, crosstalk interference has been the major limitation in achieving high data rates. The introduction of a crosstalker can cause such a large disturbance that the modem is not able to adapt sufficiently fast and ...
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Fast, fixed-order, exact-least-squares algorithms for tapped-delay-line adaptive-filtering applications are presented in this paper. These new recursive algorithms require fewer operations per iteration and exhibit better numerical... more
Fast, fixed-order, exact-least-squares algorithms for tapped-delay-line adaptive-filtering applications are presented in this paper. These new recursive algorithms require fewer operations per iteration and exhibit better numerical properties than the so-called Fast-Kalman algorithm of Ljung and Falconer [1978] and the unnormalized, least-squares, joint-process-lattice algorithms of Morf and Lee [1978]. In comparison with the currently used stochastic-gradient or LMS adaptive algorithm of
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Interest has been growing in the use of sophisticated detection methods to increase the density of bits that can be stored on a disk. Decision Feedback Equalization (DFE) is a strong candi-date among these methods, especially when... more
Interest has been growing in the use of sophisticated detection methods to increase the density of bits that can be stored on a disk. Decision Feedback Equalization (DFE) is a strong candi-date among these methods, especially when implemented as an adaptive filter[l]. An ...
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Page 1. Buffer State Information: Two-Level Water-Filling for Fixed Rate Applications Vinay Majjigi, Daniel O'Neill and John Cioffi {vmajjigi,dconeill,cioffi@stanford.edu} ... Then the buffer occupancy progression is given... more
Page 1. Buffer State Information: Two-Level Water-Filling for Fixed Rate Applications Vinay Majjigi, Daniel O'Neill and John Cioffi {vmajjigi,dconeill,cioffi@stanford.edu} ... Then the buffer occupancy progression is given as, bn = bn−1 + Rn − Rreq = b0 + n ∑ i=1 Ri − nRreq (1) ...
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diversity, ” IEEE Commun. Lett., vol. 9, no. 10, pp. 948–950, Oct. 2005. [2] S. Patil and G. de Veciana, “Reducing feedback for opportunistic schedul-ing in wireless systems, ” IEEE Trans. Wireless Commun., vol. 6, no. 12,
We study the problem of optimizing the mapping of LDPC codes on parallel machines to minimize the communication cost. To reduce the search space, the problem is solved in two stages: clustering, and cluster allocation. We propose a... more
We study the problem of optimizing the mapping of LDPC codes on parallel machines to minimize the communication cost. To reduce the search space, the problem is solved in two stages: clustering, and cluster allocation. We propose a simplified clustering technique based on a modified min-cut algorithm that reduces the search complexity from O(n2) to O(n). It was found that
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Discrete multitone transmission (DMT) [l, 21 has be-come an accepted line code for use in high data rate bandwidth efficient systems, such as asymmetric digital subscriber lines (ADSL) . DMT mitigates intersymbol interference and... more
Discrete multitone transmission (DMT) [l, 21 has be-come an accepted line code for use in high data rate bandwidth efficient systems, such as asymmetric digital subscriber lines (ADSL) . DMT mitigates intersymbol interference and optimizes the spectrum of the trasmit-ted signal by ...
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Digital Subscriber Line (DSL) Internet subscriptions form an overwhelming majority (60 70%) of the world’s 700+ million fixed-line access connections today. While the name for any DSL link may have changed terminology to “G.fast”, “homes... more
Digital Subscriber Line (DSL) Internet subscriptions form an overwhelming majority (60 70%) of the world’s 700+ million fixed-line access connections today. While the name for any DSL link may have changed terminology to “G.fast”, “homes passed”, “fiber-tothe-curb/node/basement/distribution-point”, etc., those same copper twisted-pairs today are the workhorse delivery mechanism to billions of end-user devices and Internet endpoints in residential and commercial connections. Even though the transmission characteristics of fiber may be better, it is the cost of replacing copper by fiber that has delayed the promises of fiber to everyone’s home for over 40 years. This article provides an update on some of the most recent developments in DSL technology.
This paper investigates the problem of maximizing the spectral efficiency for adaptive modulated systems with a peak power constraint. The solutions for both the continuous constellation case and the discrete constellation case are... more
This paper investigates the problem of maximizing the spectral efficiency for adaptive modulated systems with a peak power constraint. The solutions for both the continuous constellation case and the discrete constellation case are derived by the Lagrangian method,and an iterative algorithm solving the Karush-Kuhn-Tucker (KKT) optimality conditions are proposed. Our simulation results show that the spectral efficiency loss due to
Research Interests: Mathematics, Iterative Methods, Fading Channel, Noise, Fading, and 15 moreBit Error Rate, Rayleigh fading, Adaptive modulation, BER, Interference, Qam, SNR, Signal to Noise Ratio, Lagrangian Method, Optimality Condition, Quadrature Amplitude Modulation, Peak Power, Channel Capacity, Fading channels, and Iterative Algorithm
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Research Interests: Computer Science, System Identification, Nonlinear filters, Frequency, Adaptive Filter, and 12 moreThroughput, Adaptive Filters, Linear Systems, Vectors, Time Domain, Length Measurement, Initial Condition, Adaptive Algorithm, Time measurement, Recursive Least Square, Frequency Domain, and Finite Impulse Response Filter
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P.4UL ALGOET and JOHN CIOFFI Information Systems Laboratory. Durand 141B, Stanford CA 94305 We study modulation and equalization schemes to achiel-e the capacity of a vector channel with additive gaussian noise and intersymbol... more
P.4UL ALGOET and JOHN CIOFFI Information Systems Laboratory. Durand 141B, Stanford CA 94305 We study modulation and equalization schemes to achiel-e the capacity of a vector channel with additive gaussian noise and intersymbol interference. \$-e thereby reduce the ...
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Research Interests: Computer Science and IEEE
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AbstractWe present a new algorithm for blind symbol synchronization in orthogonal frequency division multiplexing (OFDM) systems. The new algorithm declares symbol synchro-nization when a certain autocorrelation matrix, constructed from... more
AbstractWe present a new algorithm for blind symbol synchronization in orthogonal frequency division multiplexing (OFDM) systems. The new algorithm declares symbol synchro-nization when a certain autocorrelation matrix, constructed from the received signal, achieves ...