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Stephen B. Weinstein

Other affiliations: Bell Labs
Bio: Stephen B. Weinstein is an academic researcher from Telcordia Technologies. The author has contributed to research in topics: Adaptive equalizer & Data transmission. The author has an hindex of 16, co-authored 38 publications receiving 4651 citations. Previous affiliations of Stephen B. Weinstein include Bell Labs.

Papers
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Journal ArticleDOI
TL;DR: Performance is evaluated under the assumption of high signal-to-noise ratio (SNR), and the resultant error probability is a good approximation for coarse quantization, and an upper bound for any degree of quantization is suggested.
Abstract: The degree of complexity of a digital signal processor is closely related to the precision with which samples of an incoming analog waveform are represented. There is considerable interest in determining how coarse this representation can be without seriously degrading performance from that of an ideal processor of unquantized samples. This question is examined for a receiver of noisy, linearly distorted pulse amplitude modulation (PAM) signals. An optimum [maximum likelihood (ML)] detector, analogous to the Viterbi detector for unquantized samples, is derived for the case of a quantized sample sequence. Performance is evaluated under the assumption of high signal-to-noise ratio (SNR), and the resultant error probability is a good approximation for coarse quantization, and an upper bound for any degree of quantization. For a specified error probability, the degree of quantization suggested by this approach is conservative. Since receiver complexity is closely associated with the length of the digital representation of an input sample, an upper bound on receiver complexity is also suggested. Numerical evaluation of the error probability is quite tedious for an arbitrary channel; however, system performance may be readily evaluated for partial-response (PR) signaling. For the PR channels

2 citations

Book ChapterDOI
01 Jan 1992
TL;DR: This chapter begins a detailed examination of signaling techniques for pulse trains, which constitute the art of conveying digital information through analog channels, which means essentially all channels, since every meaningful physical channel is analog.
Abstract: The foregoing chapters have given an overview of data communications, and reviewed topics in statistical communication theory, coding, and computer communication relevant to data communications analysis and systems design. Chapter 2 in particular described detection techniques for isolated pulse signaling. This chapter begins a detailed examination of signaling techniques for pulse trains. Such techniques constitute the art of conveying digital information through analog channels, which means essentially all channels, since every meaningful physical channel is analog. They include telephone channels, twisted-pair subscriber access lines, magnetic recording channels, shared coaxial media, and optical fiber channels. Not all of the discussion is analytical, for signal design is to some extent a collection of clever techniques developed over time, but there are some unifying theoretical foundations.

1 citations

Book ChapterDOI
01 Jan 1992
TL;DR: The purpose of this chapter is to present the various aspects of synchronization, including carrier phase coherency, which is present in the detection of passband signals.
Abstract: The theme of this chapter might well be “…timing is everything.” In the course of our discussion in Chapter 4, we saw that the detection of a baseband digital data sequence presumed proper timing at the receiver. (See Section 4.10, particularly.) The same requirement for timing is present in the detection of passband signals; however, as we saw in Section 5.2, carrier phase coherency is also necessary. The roles of each of these synchronization subsystems are shown in Figure 6.1a. The carrier tracking system provides an estimate of the received carrier phase θ^, while the timing recovery system provides an estimate of the proper sampling epoch to the receiver sampling system A^. The effect of a poorly designed carrier loop will be to increase the dispersion of the received symbols about their nominal values, bringing the received points considerably closer to the decision boundaries and decreasing the margin against an error (caused say by a noise burst); of course, large phase perturbations can cause errors without any noise. In Figure 6.1b we show how the transmitted symbol s 1 is rotated by phase jitter to the point u, and then further distorted by noise to the point z; note that the received point is within the decision region associated with s 2 so that an error will be made. Similarly, timing phase errors will cause the receiver to sample away from the maximum eye opening, and reduce the margin for error. It is the purpose of this chapter to present the various aspects of synchronization.

1 citations

Journal ArticleDOI
Stephen B. Weinstein1
TL;DR: It is shown that under certain moderate conditions, a large class of passband data signals, including all two-dimensional signal sets and many multilevel frequency-shift keying signals, can be constructed from a finite set of stored waveforms.
Abstract: It is shown that under certain moderate conditions, a large class of passband data signals, including all two-dimensional signal sets and many multilevel frequency-shift keying (FSK) signals, can be constructed from a finite set of stored waveforms. A description is given of a transversal filter with time-varying tap weights which can generate this class of signals. The configuration is amenable to digital implementation and to use in program-controlled systems.

1 citations

Patent
11 Sep 1980
TL;DR: In this article, a master modem and a plurality of tributary modems are interconnected via respective transmission channels, and the master samples and equalizes the received timing acquisition signal to form a succession of timing acquisition equalizer outputs.
Abstract: In a multipoint data communication system a master modem and a plurality of tributary modems are interconnected via respective transmission channels. Adaptive equalizer circuitry (55,56) in the master modem equalizes the channel from a particular tributary by multiplying samples of signals received from the tributary by an appropriate ensemble of tap coefficients stored in a memory (91). Timing-acquisition circuitry (29) adjusts the phase of the master's sampling circuitry (23, 27) at the start of transmission from a given tributary so that the received signals are sampled at the correct time points. In order to do this, a timing acquisition signal having spectral components only within the non-rolloff region of the equalized baseband-equivalent transfer function is transmitted by the tributary. The master samples and equalizes the received timing acquisition signal to form a succession of timing acquisition equalizer outputs.

1 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors examined the performance of using multi-element array (MEA) technology to improve the bit-rate of digital wireless communications and showed that with high probability extraordinary capacity is available.
Abstract: This paper is motivated by the need for fundamental understanding of ultimate limits of bandwidth efficient delivery of higher bit-rates in digital wireless communications and to also begin to look into how these limits might be approached. We examine exploitation of multi-element array (MEA) technology, that is processing the spatial dimension (not just the time dimension) to improve wireless capacities in certain applications. Specifically, we present some basic information theory results that promise great advantages of using MEAs in wireless LANs and building to building wireless communication links. We explore the important case when the channel characteristic is not available at the transmitter but the receiver knows (tracks) the characteristic which is subject to Rayleigh fading. Fixing the overall transmitted power, we express the capacity offered by MEA technology and we see how the capacity scales with increasing SNR for a large but practical number, n, of antenna elements at both transmitter and receiver. We investigate the case of independent Rayleigh faded paths between antenna elements and find that with high probability extraordinary capacity is available. Compared to the baseline n = 1 case, which by Shannon‘s classical formula scales as one more bit/cycle for every 3 dB of signal-to-noise ratio (SNR) increase, remarkably with MEAs, the scaling is almost like n more bits/cycle for each 3 dB increase in SNR. To illustrate how great this capacity is, even for small n, take the cases n = 2, 4 and 16 at an average received SNR of 21 dB. For over 99% of the channels the capacity is about 7, 19 and 88 bits/cycle respectively, while if n = 1 there is only about 1.2 bit/cycle at the 99% level. For say a symbol rate equal to the channel bandwith, since it is the bits/symbol/dimension that is relevant for signal constellations, these higher capacities are not unreasonable. The 19 bits/cycle for n = 4 amounts to 4.75 bits/symbol/dimension while 88 bits/cycle for n = 16 amounts to 5.5 bits/symbol/dimension. Standard approaches such as selection and optimum combining are seen to be deficient when compared to what will ultimately be possible. New codecs need to be invented to realize a hefty portion of the great capacity promised.

10,526 citations

Journal ArticleDOI
TL;DR: The general technique of parallel transmission on many carriers, called multicarrier modulation (MCM), is explained, and the performance that can be achieved on an undistorted channel and algorithms for achieving that performance are discussed.
Abstract: The general technique of parallel transmission on many carriers, called multicarrier modulation (MCM), is explained. The performance that can be achieved on an undistorted channel and algorithms for achieving that performance are discussed. Ways of dealing with channel impairments and of improving the performance through coding are described, and implementation methods are considered. Duplex operation of MCM and the possible use of this on the general switched telephone network are examined. >

3,995 citations

Book
31 Aug 1994
TL;DR: The use of infrared radiation as a medium for high-speed short-range wireless digital communication, and several modification formats, including on-off keying (OOK), pulse-position modulation (PPM), and subcarrier modulation, are discussed.
Abstract: The use of infrared radiation as a medium for high-speed short-range wireless digital communication is discussed. Available infrared links and local-area networks are described. Advantages and drawbacks of the infrared medium are compared to those of radio and microwave media. The physical characteristics of infrared channels using intensity modulation with direct detection (IM/DD) are presented including path losses and multipath responses. Natural and artificial ambient infrared noise sources are characterized. Strategies for designs of transmitter and receivers that maximize link signal-to-noise ratio (SNR) are described. Several modification formats are discussed in detail, including on-off keying (OOK) pulse-position modulation (PPM), and subcarrier modulation. The performance of these techniques in the presence of multipath distortion is quantified. Techniques for multiplexing the transmissions of different users are reviewed. The performance of an experimental 50-Mb/s on-off-keyed diffuse infrared link is described.

2,972 citations

Journal ArticleDOI
D. Godard1
TL;DR: This paper solves the general problem of adaptive channel equalization without resorting to a known training sequence or to conditions of limited distortion.
Abstract: Conventional equalization and carrier recovery algorithms for minimizing mean-square error in digital communication systems generally require an initial training period during which a known data sequence is transmitted and properly synchronized at the receiver. This paper solves the general problem of adaptive channel equalization without resorting to a known training sequence or to conditions of limited distortion. The criterion for equalizer adaptation is the minimization of a new class of nonconvex cost functions which are shown to characterize intersymbol interference independently of carrier phase and of the data symbol constellation used in the transmission system. Equalizer convergence does not require carrier recovery, so that carrier phase tracking can be carried out at the equalizer output in a decision-directed mode. The convergence properties of the self-recovering algorithms are analyzed mathematically and confirmed by computer simulation.

2,645 citations

Journal ArticleDOI
Jr. L.J. Cimini1
TL;DR: The analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel using the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel is discussed.
Abstract: This paper discusses the analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel. This system uses the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel. When this technique is used with pilot-based correction, the effects of flat Rayleigh fading can be reduced significantly. An improvement in signal-to-interference ratio of 6 dB can be obtained over the bursty Rayleigh channel. In addition, with each subchannel signaling at a low rate, this technique can provide added protection against delay spread. To enhance the behavior of the technique in a heavily frequency-selective environment, interpolated pilots are used. A frequency offset reference scheme is employed for the pilots to improve protection against cochannel interference.

2,627 citations