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Excision Techniques In Direct Sequence Spread Spectrum Communication Systems
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Book Synopsis Excision Techniques in Direct Sequence Spread Spectrum Communication Systems by :
Download or read book Excision Techniques in Direct Sequence Spread Spectrum Communication Systems written by and published by . This book was released on 1990 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents a comprehensive summary of a number of methods used in filtering narrowband jammers and interference out of direct sequence spread spectrum communication systems. The basic concept is presented first followed by a discussion of several analog techniques for interference suppression. Most of the emphasis is on digital adaptive methods, which rely on adaptive filtering algorithms. Many of these algorithms are highlighted. This is followed by a discussion on the research which has been conducted in digital excision over the past several years. Two cases based on the author's work are also presented. The first details the performance one can expect from the recursive least squares algorithm when the interferer is a stable tone. An analytical model, which predicts the bit error rate performance for the recursive algorithm under certain conditions, is derived. This model is compared to results obtained from computer simulation, the tracking and filtering capabilities of hte block and recursive least square algorithms when the interference is of the FM-type, i.e., a swept tone having a bandwidth which is approximately 20% of the chip rate. (Author).
Book Synopsis Time-Frequency Receivers for Nonstationary Interference Excision in Spread Spectrum Communication Systems by :
Download or read book Time-Frequency Receivers for Nonstationary Interference Excision in Spread Spectrum Communication Systems written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-Frequency distribution are being recognized as powerful tools in signal analysis and processing. Although time-frequency analysis has been of interest for some-time, several advances in recent years have broaden its application areas to include both civilian and military use. The capability of the time-frequency distributions to properly represent multiple component signals in time and frequency permits the development of new and efficient approaches for interference excision in direct sequence spread spectrum communication systems. This report addresses techniques for mitigating nonstationary interference in spread spectrum communication systems; and fast algorithms and efficient realizations of excision techniques based on time-frequency distributions. The scope of this effort is to develop technology to immunize the spread spectrum communication systems to smart jamming and demonstrate the ability to yield improved receiver performance in a highly nonstationary interference environment. This is achieved by utilizing the jammer temporal, spectral, and spatial characteristics to provide accurate and sufficient information leading to its full and effective excision.
Book Synopsis Perspectives in Spread Spectrum by : Amer A. Hassan
Download or read book Perspectives in Spread Spectrum written by Amer A. Hassan and published by Springer Science & Business Media. This book was released on 1998-08-31 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perspectives in Spread Spectrum brings together studies and recent work on six exciting topics from the spread spectrum arts. The book gives a wide, collective view of trends, ideas, and techniques in the spread spectrum discipline, due to the authors' extensive work on spread spectrum techniques and applications from different vantage points. The inexorable march of electronics towards ever faster, ever smaller, and ever more powerful electronic and optical circuitry has wrought, and will continue to enable, profound changes in the spread spectrum arts, by allowing increasingly complex signalling waveforms and statistical tests to be implemented as the theory beyond spread spectrum continues to evolve. Perspectives in Spread Spectrum is divided into six chapters. The first chapter deals with sequence spreading design. There is not a single metric for design of spreading sequences; rather, the design is ideally tailored to the specific scenario of usage. This chapter delves into recent and very promising synthesis work. The second chapter deals with OFDM techniques. As channels become wider and trans-channel fading (or jamming) becomes frequency selective across the band, OFDM techniques may provide a powerful alternative design perspective. The third chapter is a generalization of the venerable Walsh functions. A new modulation scheme, Geometric Harmonic Modulation, GHM for short, is reviewed and characterized as a form of OFDM. From GHM, a further generalization of the Walsh functions is derived for non-binary signalling. The fourth chapter is concerned with some new and exciting results regarding the follower jammer paradigm. A counter-countermeasure technique is reviewed, notable for its counterintuitive characteristic which can be understood from a simple yet elegant game framework. The fifth chapter recounts some results pertaining to random coding for an optical spread spectrum link. The technique is based on laser speckle statistics and uses a coherent array of spatial light modulators at the transmitter but allows the receiver to be realized as a spatially distributed radiometric and therefore incoherent structure. The sixth and final chapter looks at an important and interesting application of spread spectrum to accurately locate a wideband, ‘bent pipe’, satellite transponder. It is, in a strong sense, an inverted GPS technique. Perspectives in Spread Spectrum serves as an excellent reference and source of ideas for further research, and may be used as a text for advanced courses on the topic.
Book Synopsis Analysis of Interference Excision Algorithms for Direct Sequence Spread Spectrum Signals by : Harvey Hum
Download or read book Analysis of Interference Excision Algorithms for Direct Sequence Spread Spectrum Signals written by Harvey Hum and published by . This book was released on 1994 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Analysis of Modified Direct Sequence Spread-spectrum Techniques Applied to Multiple Access Communications by : John William Porter
Download or read book An Analysis of Modified Direct Sequence Spread-spectrum Techniques Applied to Multiple Access Communications written by John William Porter and published by . This book was released on 1984 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Spread Spectrum Communications by : Marvin K. Simon
Download or read book Spread Spectrum Communications written by Marvin K. Simon and published by . This book was released on 1985 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Application of Autoregressive Methods to Adaptive Excision of Interfering Tones from Direct Sequence Spread Spectrum Communications Systems by : Brian W. Kozminchuk
Download or read book Application of Autoregressive Methods to Adaptive Excision of Interfering Tones from Direct Sequence Spread Spectrum Communications Systems written by Brian W. Kozminchuk and published by . This book was released on 1988 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Computer Simulation of a BPSK Direct Sequence Spread Spectrum System has been developed to investigate the effects of adaptively filtering stable tone interferers covering twenty per cent of the communication band. Preliminary results for the swept tone interfering signal are also presented and shows that the block filter is effective when the tones are stable, but degrades in performance as the tone sweeps quickly across the band. To combat the non-stationary signal environment, either shorter block lengths may be required or the use of recursive algorithms that are based on gradient or least square concepts may have to be examined. Keywords: Spread spectrum; Binary phase shift keyers; Spectrum estimation; Computer simulation; Autoregressive processes; Maximum entropy method; Least squares; Adaptive filtering; Signal excision; Weiner filtering; Linear prediction; Canada. (jd/rh).
Book Synopsis Direct Sequence Spread Spectrum in Communication System by : Ngoc Hoa Thach
Download or read book Direct Sequence Spread Spectrum in Communication System written by Ngoc Hoa Thach and published by . This book was released on 2004 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Parallel Acquisition of Spreading Sequences in Direct-sequence Spread-spectrum Communication Systems by : Zhiyuan Yan
Download or read book Parallel Acquisition of Spreading Sequences in Direct-sequence Spread-spectrum Communication Systems written by Zhiyuan Yan and published by . This book was released on 1999 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Direct Sequence Spread Spectrum Techniques by : J. E. Hershey
Download or read book Direct Sequence Spread Spectrum Techniques written by J. E. Hershey and published by . This book was released on 1984-07-01 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Parallel Acquisition of Spreading Sequences in Direct-sequence Spread-spectrum Communication Systems by : Meera Srinivasan
Download or read book Parallel Acquisition of Spreading Sequences in Direct-sequence Spread-spectrum Communication Systems written by Meera Srinivasan and published by . This book was released on 1996 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parallel search schemes are presented for the acquisition of spreading sequences in chip-asynchronous direct-sequence spread-spectrum communication systems. In a parallel acquisition scheme, an estimate of the delay of a direct-sequence signal is made directly from a number of correlations of the received signal against different shifted versions of the spreading signal. Parallel schemes acquire the signal very quickly, but are more computationally intensive than serial schemes. In this thesis, we investigate several parallel strategies for the acquisition for general binary spreading sequences and develop suboptimal acquisition schemes that are easier to implement than the previously proposed optimal schemes. The techniques presented are attractive in that they approximate the optimal parallel schemes in terms of probability of successful acquisition, but are much easier to implement than the optimal schemes. The single-user phase-coherent situation is considered first. In this case, both carrier frequency and phase are known. We first discuss the optimal and maximum likelihood estimators for general binary spreading sequences and then present two new suboptimal schemes. One of these schemes is a small signal approximation of the optimal scheme, and it performs very well over a large range of signal-to-noise ratio. The other scheme is a hybrid of the optimal and maximum likelihood schemes, and is extremely simple. The hybrid scheme can be analyzed precisely in terms of its probability of unsuccessful acquisition. It is shown that this hybrid scheme has error probability decreasing exponentially with increasing SNR, and that this scheme is practically the simplest possible parallel scheme that has this property. Our result also proves an earlier conjecture that the optimal parallel estimator has error probability that decreases exponentially with increasing SNR. The same approach is used to devise simple acquisition schemes for the single-user noncoherent situation. A locally optimal estimator for low SNR is presented, along with two different noncoherent analogues of the coherent hybrid scheme. One of the noncoherent hybrid schemes is analyzed, and it is shown that this scheme also has exponentially decreasing error probability. This also proves that the error probability of the optimal noncoherent estimator decreases exponentially with increasing SNR. The problem of acquiring several direct-sequence signals in the absence of data modulation is also considered. The chip-synchronous situation is considered first and decorrelating methods are used to develop two near-far resistant strategies. One of these schemes estimates the signal delays in multiple stages, with each delay estimate depending on previous delay estimates, while the other scheme estimates the delays simultaneously and independently of each other. Schemes for the chip-asynchronous case are then developed by combining the coherent hybrid scheme for the single-user situation with the multistage decorrelating method. Monte Carlo simulation is used to obtain the error probabilities for the various schemes.
Book Synopsis Advanced Techniques for Direct Sequence Spread Spectrum Acquisition by : Alem, Ahmad Waddah Kayyaly
Download or read book Advanced Techniques for Direct Sequence Spread Spectrum Acquisition written by Alem, Ahmad Waddah Kayyaly and published by . This book was released on 1977 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Acquisition Techniques for Direct Sequence Spread Spectrum Packet Radio Systems by : Zhen-liang Shi
Download or read book Acquisition Techniques for Direct Sequence Spread Spectrum Packet Radio Systems written by Zhen-liang Shi and published by . This book was released on 1993 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Study of Binary Sequences for Direct-Sequence Spread-Spectrum Multiple-Access Communication Systems by : 陳子健
Download or read book A Study of Binary Sequences for Direct-Sequence Spread-Spectrum Multiple-Access Communication Systems written by 陳子健 and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "A Study of Binary Sequences for Direct-sequence Spread-spectrum Multiple-access Communication Systems" by 陳子健, Chi-kin, John Baptist, Chan, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3121276 Subjects: Spread spectrum communications
Book Synopsis Band-reject Filtering for Direct-sequence Spread Spectrum Communication Systems by : John Edward Uth
Download or read book Band-reject Filtering for Direct-sequence Spread Spectrum Communication Systems written by John Edward Uth and published by . This book was released on 1985 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interference Mitigation in Spread Spectrum Systems Using Lapped Transforms by :
Download or read book Interference Mitigation in Spread Spectrum Systems Using Lapped Transforms written by and published by . This book was released on 2002 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, linear and non-linear transform domain filtering techniques are examined and proposed as a means of enhancing the inherent interference immunity associated with direct sequence spread spectrum communication receivers. This analysis begins with a review of block transform domain Wiener filters and is further developed in the lapped transform domain. The latter part of this report addresses the use of lapped transforms to transform the received data signal into the transform domain wherein adaptive excision is performed. System performance results are presented for a variety of channel conditions and compared to those obtained using orthonormal block transforms. These results demonstrate the improved performance and increased robustness with respect to jammer frequency and bandwidth of lapped transform domain excision techniques relative to similar algorithms based on non-weighted block transforms.
Book Synopsis Direct Sequence Spread-spectrum Communication System by : Timothy John Malone
Download or read book Direct Sequence Spread-spectrum Communication System written by Timothy John Malone and published by . This book was released on 1983 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
