Stephen B. Weinstein

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.

Feedback error control system

Abstract: Information sequences are encoded into a block code and both transmitted to a receiving terminal and stored at the transmitting terminal. The transmitted blocks are decoded at the receiving terminal and if uncorrectable errors are detected in a block, the receiving terminal transmits a feedback word to the transmitting terminal indicating that errors have been detected in the block in question. If uncorrectable errors have not occurred, the receiving terminal transmits to the transmitting terminal another feedback word which is a reduced version of the information portion of the block in question. Upon receipt of the feedback word, the transmitting terminal decides if a retransmission is required; if so, it substitutes, for the parity sections of subsequently transmitted blocks, that information sequence corresponding to the erroneous block.

Introduction to Data Communications

Abstract: Data communication has been with us for a long time. Smoke signals, drum beats, and semaphore signals are examples that are commonly given; indeed, semaphore relay may be regarded as the first modern communication network [1]. But the most remarkable example must surely be alphabetical writing. The concept of conveying information by successive choices from a finite alphabet is the very essence of both writing and digital data communication [2]. In fact, many of the ideas of linguistics carry over to information theory, communications, and pattern recognition. It is the purpose of this first chapter, in a book devoted to the principles of data communications, to provide a perspective on the technology of data communications, and to highlight the broad applicability of the foundation technologies of modulation/demodulation, equalization, coding, and synchronization. In this text we will demonstrate the communication-theoretic origin and the broad application of these technologies to a variety of communication media, including the telephone channel, twisted pairs, radio, magnetic recording, and optical fiber.

A First Look at the Application of Signal Extraction Techniques to the Analysis of Body Surface Potential Maps

Abstract: Partial body surface potential maps from both normal subjects and subjects with independently diagnosed myocardial infarcts are visually compared from superimposed plots. A correlation test is devised to distinguish the two groups, with the reference waveform determined by means of a gradient-search algorithm. The results are encouraging, and suggest further investigation of these techniques as a future diagnostic tool.

Introduction to "the history of ofdm" the history of orthogonal frequency-division multiplexing

Abstract: Orthogonal frequency-division multiplexing (OFDM) is one of those ideas that had been building for a very long time, and became a practical reality when the appearance of mass market applications coincided with the availability of efficient software and electronic technologies. This article describes the background and some of the striking early development of OFDM, with explanation of the motivations for using it. I presume a broad definition of OFDM as frequency-division multiplexing (FDM) in which subchannels overlap without interfering. It does not not necessarily require the discrete Fourier transform (DFT) or its fast Fourier transform (FFT) computational method.

On Limits of Wireless Communications in a Fading Environment when UsingMultiple Antennas

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.

Multicarrier modulation for data transmission: an idea whose time has come

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. >

Wireless Infrared Communications

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.

Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems

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.

Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing

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.