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Author: Behnaam Aazhang Publisher: ISBN: Category : Languages : en Pages : 148
Book Description
Performance of digital linear and nonlinear correlation receivers is studied in a muli-user environment. There are assumed to be two types of sources interfering with data transmission: multiple-access interference, and additive channel noise, which is attributed to impulsive noise sources in the environment. The contribution of multiple-access interference is examined by considering K users transmitting simultaneously over a linear channel using the binary PSK direct-sequence SSMA technique. Alternatively, the effects of the non-Gaussian impulse channel in such a system are studied by modeling the sample of noise after front-end filtering. The performance of hard-limiting correlation receivers is compared with that of conventional linear correlation receivers in such channels by exact computation of the average bit error probabilities of these two systems. It is seem that hard-limiting correlation receivers can offer substantial improvement over the conventional linear correlator when the additive non-Gaussian channel noise exhibits impulsive behavior.
Author: Behnaam Aazhang Publisher: ISBN: Category : Languages : en Pages : 148
Book Description
Performance of digital linear and nonlinear correlation receivers is studied in a muli-user environment. There are assumed to be two types of sources interfering with data transmission: multiple-access interference, and additive channel noise, which is attributed to impulsive noise sources in the environment. The contribution of multiple-access interference is examined by considering K users transmitting simultaneously over a linear channel using the binary PSK direct-sequence SSMA technique. Alternatively, the effects of the non-Gaussian impulse channel in such a system are studied by modeling the sample of noise after front-end filtering. The performance of hard-limiting correlation receivers is compared with that of conventional linear correlation receivers in such channels by exact computation of the average bit error probabilities of these two systems. It is seem that hard-limiting correlation receivers can offer substantial improvement over the conventional linear correlator when the additive non-Gaussian channel noise exhibits impulsive behavior.
Author: David Edward Borth Publisher: ISBN: Category : Languages : en Pages : 366
Book Description
The performance of biphase direct-sequence spread-spectrum multiple-access (SSMA) communication for a general class of fading channels is investigated. The channels considered are those for which the channel output consists of a strong stable specular signal plus a faded version of this signal. Such channels are the result of a transmission medium which gives rise to a major stable communication path and a number of additional weaker communication paths. The fading channel is modeled as a general is modeled as a general wide-sense-stationary uncorrelated-scattering (WSSUS) channel -- a model which is general enough to exhibit both time and frequency selectivity and to impose no restrictions on the fading rate. A discussion of the important parameters of the WSSUS channel is given and two important classes of WSSUS channels are developed from the general fading channel model; time-selective fading channels and frequency-selective fading channels. In analyzing the performance of direct-sequence SSMA communications via fading channels two measures of system performance that are considered are average signal-to-noise ratio at the receiver output and the average probability of error. (Author).
Author: H. V. Poor Publisher: ISBN: Category : Languages : en Pages : 7
Book Description
The overall purpose of this research project was to seek new methods for improving the robustness and efficiency of spread-spectrum communications systems operating over non-Gaussian channels. The study was motivated in large part by the fact that modern military radio networks must operate in complex and variable noise environments that are often dominated by impulsive, non-Gaussian man-made noise sources. The research under this contract progressed in three basic areas: (1) optimum multiuser demodulation techniques; (2) direct-sequence spread-spectrum multiple-access (DS/SSMA) signaling through impulsive channels; and (3) improved suppression of narrowband interferers from spread-spectrum signals. The common thread binding these three disparate multiuser-communications research topics is the fact that each involves the processing of signals in non-Gaussian interference. In the first case, the non-Gaussian interference is the multiuser noise interfering with the demodulation of a given user; in the second case, the non-Gaussian interference is the impulsive noise dominating the channel; and in the third case, the non-Gaussian interference is the spread-spectrum signal itself as it interferes with the prediction and consequent excision of the narrowband interferer. (rh).
Author: Matthew G. Glen Publisher: ISBN: 9781423519928 Category : Coding theory Languages : en Pages : 78
Book Description
This research characterizes MAI effects on DS/SSMA system performance through simulation in Matlab , and explores the impact of multiple access code selection, chip waveform shaping, and multiple access code length on BER for both synchronous and asynchronous multiple access networks. In addition, the simulated DS/SSMA model permits rapid research into the effects of additional factors on BER. Prior to experimental testing, model validation is conducted through single user trials and by comparison with existing research for similar system designs. For synchronous and asynchronous networks, Gold coding improves BER by 7.5 and 4.0 dB, respectively, relative to aperiodic random spreading codes. Synchronous network results show that chip waveform shaping provides no significant BER improvement for the Blackman or Lanczos shapes. However, asynchronous network results show a potential BER improvement for Blackman and Lanczos shapes. Increasing code length from 31 to 511 resulted in a 7.5 dB BER improvement. Collectively, these results directly relate changes in BER to waveform cross-correlation statistics.
Author: Paul R. Prucnal Publisher: CRC Press ISBN: 1351837001 Category : Science Languages : en Pages : 292
Book Description
Code-division multiple access (CDMA) technology has been widely adopted in cell phones. Its astonishing success has led many to evaluate the promise of this technology for optical networks. This field has come to be known as Optical CDMA (OCDMA). Surveying the field from its infancy to the current state, Optical Code Division Multiple Access: Fundamentals and Applications offers the first comprehensive treatment of OCDMA from technology to systems. The book opens with a historical perspective, demonstrating the growth and development of the technologies that would eventually evolve into today's optical networks. Building on this background, the discussion moves to coherent and incoherent optical CDMA coding techniques and performance analysis of these codes in fiber optic transmission systems. Individual chapters provide detailed examinations of fiber Bragg grating (FBG) technology including theory, design, and applications; coherent OCDMA systems; and incoherent OCDMA systems. Turning to implementation, the book includes hybrid multiplexing techniques along with system examples and conversion techniques to connect networks that use different multiplexing platforms, state-of-the-art integration technologies, OCDMA network security issues, and OCDMA network architectures and applications, including a look at possible future directions. Featuring contributions from a team of international experts led by a pioneer in optical technology, Optical Code Division Multiple Access: Fundamentals and Applications places the concepts, techniques, and technologies in clear focus for anyone working to build next-generation optical networks.
Author: 葉冠華 Publisher: Open Dissertation Press ISBN: 9781374766402 Category : Languages : en Pages :
Book Description
This dissertation, "A Study of Direct-sequence Spread-spectrum Multiple-access Communications Over Multipath Rayleigh Fading Channels" by 葉冠華, Kun-wah, Yip, 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_b3123454 Subjects: Spread spectrum communications
Author: Behnaam Aazhang
Author: Behnaam Aazhang
Author: David Edward Borth
Author: Fatih M. Ozluturk
Author: H. V. Poor
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Author: Matthew G. Glen
Author: 
Author: Paul R. Prucnal
Author: 葉冠華
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