Download or read book Interference Suppression in Multiple Access Communications Using M Ary Phase Shift Keying Generated Via Spectral Encoding written by Abel S. Nunez and published by . This book was released on 2004-03-01 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: A conceptual transform domain communication system (TDCS) is shown capable of operating successfully using M-Ary phase shift keying (MPSK) data modulation in a multiple access environment. Using spectral encoding, the conceptual TDCS provides an effective means for mitigating interference affects while achieving multiple access communications. The use of transform domain processing with MPSK data modulation (TD-MPSK) provides higher spectral efficiency relative to other modulation techniques (antipodal signaling and cyclic shift keying) considered previously for TDCS applications. The proposed TD-MPSK technique uses spectral encoding for both data and multiple access phase modulations. Demodulation of the spectrally encoded TD-MPSK communication symbols is accomplished using conventional, multi-channel time domain correlation techniques. Analytic expressions for TD-MPSK probability of symbol error (PE) and probability of bit error (PB) are derived and validated using simulated results over the range of signal-to-noise ratios typically considered for communications. This validation includes scenarios with: 1) multiple access interference, 2) spectral notching, 3) jamming present and 4) combinations of all three. For a J/S of 3.14 dB and a Eb/N0 of 6 dB, PB dropped by up to a factor of 3 for TD-QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasn't present. The cross- correlation between communication symbols of different synchronous users can be made identically zero through proper selection of multiple access phase codes (orthogonal signaling). For a synchronous network containing orthogonal users, PE and PB are unaffected as the number of orthogonal network users increases. For a J/S of 3.14 dB and a Eb/N0 of 6 dB, PB dropped by a factor of 12 for TD- QPSK in a MA environment for the case when spectral notching was present versus the case when spectral notching wasn't present.

Download or read book Interference Suppression in Multiple Access Communications Using M Ray Phase Shift Keying Generated Via Spectral Encoding written by Abel Sanchez Nunez and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Digital Communications with Chaos written by Wai M Tam and published by Elsevier. This book was released on 2010-07-07 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the 1970's, there has been a great deal of research effort spent on studying chaotic systems and the properties of the chaotic signals generated. Characterized by their wideband, impulse-like autocorrelation and low cross-correlation properties, chaotic signals are useful spread-spectrum signals for carrying digital information. Spectrum spreading has become one of the most popular modulation techniques for high-speed wireless communications. It makes use of signals of very wide bandwidth to carry information at relatively low data rates, and possesses advantages such as low probability of interception, resistance to jamming, multiple-access capability and mitigation to multipath effect, which are particularly important in a wireless scenario. In addition to enjoying the aforementioned benefits, chaotic signals can be generated using simple circuitries, thus lowering the cost of transceivers. Early study of chaos-based communication systems was focused on a single-user case. In the past few years, more effort has been put on investigating systems with multiple-access capability, which is a key feature of spread-spectrum communication systems. Digital Communications with Chaos presents a detailed study of some multiple-access schemes used for chaos-based communications, and evaluates their performance. In addition, the effectiveness of the multiuser detection techniques, whose primary objective is to reduce interference between users and hence improve performance, is evaluated in the context of multiple-access digital communication systems. Hot research topic Describes communication technologies for the future Authors among the pioneers researching in chaos-based communications

Download or read book Performance of a Spectrally Encoded Multi Carrier Phase Shift Keying Communications System in a Frequency Selective Slowly Fading Multipath Channel written by and published by . This book was released on 2005 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research examines the performance of a spectrally encoded, multi-carrier, phase shift keying communications system in a frequency-selective, slowly-fading multipath channel. The specific communications system modeled is the transform domain communication system (TDCS) originally researched as an interference avoidance technique. Previous TDCS research assumed an additive white gaussian noise channel, which is not representative of a realistic environment. This thesis presents overviews of previous TDCS research, the multipath fading channel, and the RAKE receiver. Analysis and Matlab simulations compare the performance of spectrally encoded and un-encoded signals through a multipath fading channel using an L-diversity TDCS RAKE receiver. Encoded signals take on the spectral shape of the multipath fading channel transfer function. Un-encoded signals have a flat magnitude spectrum. The research also evaluates the interference rejection capability of spectrally encoded signals in a multipath channel. Research results indicate for diversities ranging between 2 and 50, spectrally encoded signals need 1.0 to 2.75dB less transmitted normalized bit energy to noise power spectral density ratios to achieve the same probability of bit error as un-encoded signals. Results also demonstrate that spectrally encoded TDCS signals retain the interference rejection capability.

Download or read book Code Shift Keying Impulse Modulation for Ultra Wideband Communications written by Serhat Erküçük and published by . This book was released on 2007 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra wideband impulse radio (UWB-IR) is a promising technology that has been recently investigated for high-rate data communications and low-rate location and ranging systems. Despite its many advantages including low-cost circuitry, use of unlicensed spectrum and multipath resolving capabilities, the current implementation of UWB-IRs exhibits some problems. Firstly, the conventional UWB-IR modulation format, pulse position modulation (PPM), uses consecutive fixed pulse transmit locations that are largely affected by multipath-delayed pulses, which degrades the system performance. Secondly, increasing the data rate of the most commonly used binary PPM (BPPM) format is still an open research problem. Thirdly, periodic time-hopping (TH) codes used for multiple-access generate undesired peaks for the spectrum, which may cause increased interference levels for the systems co-existing in the same bandwidth. Considering above mentioned drawbacks of the current UWB-IRs, a new modulation format is proposed in this dissertation: Code Shift Keying (CSK) Impulse Modulation. M-ary CSK (MCSK), which can be employed by itself or combined with other UWB-IR modulations, achieves data transmission by selecting one of the M orthogonal user-specific TH codes, where these TH codes are used to randomize pulse transmit locations. While the randomized pulse transmit locations reduce the effect of multipath-delayed pulses on the system performance, the random selection of TH codes increases the effective TH code period and suppresses the undesired peaks in the spectrum. In this dissertation, CSK impulse modulation is studied in detail to quantify its performance improvement over the existing systems. Initially, MCSK is compared to M-ary PPM (MPPM) to show the advantage of randomizing pulse transmit locations over fixed locations. It is shown that MCSK can provide about 2dB performance gain over MPPM in a multipath channel. Secondly, MSCK is combined with BPPM (i.e., MCSK/BPPM) in order to increase the data rate of conventional TH-BPPM systems. It is shown that MCSK/BPPM can achieve improved system performance at increased data rate if system design parameters are properly selected. Finally, power spectral density (PSD) characteristics of MCSK based IRs are studied. It is shown that the random selection of TH codes improves the resulting PSD with respect to that of conventional UWB-IRs.

Download or read book Performance Analysis of Direct Sequence Code Division Multiple Access Communications with Asymmetric Quadrature Phase Shift Keying Modulation written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-09-16 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.Wang, C.-W. and Stark, W.Jet Propulsion LaboratoryQUADRATURE PHASE SHIFT KEYING; BINARY PHASE SHIFT KEYING; ASYMMETRY; CODE DIVISION MULTIPLE ACCESS; PHASE SHIFT KEYING; MULTIPLE ACCESS; PROTECTION; RELIABILITY ANALYSIS

Download or read book Interference Suppression in Spread Spectrum Code Division Multiple Access Communications written by Leslie Ann Rusch and published by . This book was released on 1994 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 1904 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance of a Spectrally Encoded Multi carrier Phase Shift Keying Communication System in a Frequency selective Slowly fading Multipath Channel written by Charles M. Gaona and published by . This book was released on 2005 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trellis coded Multidimensional M ary Phase Shift Keying with Full Phase Rotational Invariance written by Chin-Feng Lin and published by . This book was released on 1994 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1990 with total page 734 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book M ary Differential Phase Shift Keying with Non coherent Detection in Mobile Channels written by Shi Hong (M.E.) and published by . This book was released on 1991 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiple user Interference in a Frequency hopped Spread spectrum Communication System Using Differential Phase shift Keying written by Alex Waiho Lam and published by . This book was released on 1984 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: A design of short Reed-Solomon hopping sequences which have excellent correlation properties is proposed. Within the design, any two sequences will have at most one partial hit or one full hit when used asynchronously. The behavior of a near-optimum differential phase-shift keying (DPSK) receiver with multiple-user interference over a non-fading channel is discussed. Bit error rates for the receiver with single interference in one chip and the receiver with single interference in J distinct chips are found. Finally, generalization of the multiple-user interference model is considered. Keywords include: Near-optimum FH-DPSK receiver, Reed-Solomon frequency hopping patterns, and multiple-user interference, error probabilities.

Download or read book A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct Sequence Code Division Multiple Access Communications written by Yuejin Huang and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct-sequence Code Division Multiple Access Communications" by 黃耀進, Yuejin, Huang, 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_b3123707 Subjects: Wireless communication systems Code division multiple access Spread spectrum communications

Download or read book Frequency Hopped M ary Frequency Shift Keyed Communications Using List Metric Decoding Over Jamming and Multiple Access Channels written by Mark Alan Creighton and published by . This book was released on 1986 with total page 718 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of a Multipath Channel and Interference on Coherent M PSK Digital Communication Systems written by and published by . This book was released on 1993 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report derives expressions for the average probability of symbol error of coherent M-ary phase-shift-keyed (M-PSK) communication system operating under the following nonideal conditions: (1) time-invariant multipath channel consisting of a direct path and a single multipath, (2) intentional/ unintentional interference consisting of either a continuous wave (CW) signal or a bandpass filtered white Gaussian noise signal (bandwidth is variable), and (3) additive white Gaussian noise. Exact solutions are derived for coherent binary phase shift-keyed (BPSK) while both exact and upper bound solutions (shown to be tighter than the Chernoff bound) are derived for coherent M-PSK. One particular example, line-of-sight ultrahigh frequency (LOS UHF) radio, is used extensively to exercise the derived expressions and illustrate typical system performance. These results pertain to receiver with no means of compensation for the nonideal channel conditions. Methods of compensation for multipath and interference, like adaptive equalization, beamforming, spatial diversity, and multichannel adaptive equalization, are presently under investigation by the authors. The results in this report will help determine the performance gain offered by these methods of compensation.

Download or read book Quadrature Phase Shift Keying direct Sequence Spread Spectrum code Division Multiple Access with Disparate Quadrature Chip and Data Rates written by Shweta S. Agarwal and published by . This book was released on 2006 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: