Patent
System and method for generating signal waveforms in a CDMA cellular telephone system
Klein S. Gilhousen,Irwin M. Jacobs,Roberto Padovani,Lindsay A. Weaver,Wheatley Charles E,Andrew J. Viterbi +5 more
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TLDR
In this paper, a system and method for communicating information signals using spread spectrum communication techniques is presented, where PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance.Abstract:
A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, bi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols. In the mobile-to-cell link, access and voice channels are defined. Information communicated on the mobile-to-cell link channels are, in general, encoded, interleaved, orthogonal signaling along with QPSK spreading.read more
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Patent
Echo cancellation using cross-correlation of buffered receive and transmit sample segments to determine cancelling filter coefficients
TL;DR: An echo detection system comprises data stores (8, 18) for storing signals from up and down channels (5, 15) respectively, and signals undergo pre-processing to identify signals forms characteristic of speech and instruct the measurement unit to carry out comparison using cross-correlation techniques between the signals stored in stores only when such characteristics are detected.
Patent
Synchronous transmitter and receiver of spread spectrum communication method
Je-woo Kim,Sung-Hun Jung +1 more
TL;DR: In this paper, a synchronous transmitter and receiver utilizing a spread spectrum communication method includes a pseudo noise code generator for generating a preset pseudo noise (PN) code; a spectrum spreading device for band-spreading input data in accordance with a pseudo-noise code; and a modulator for modulating an intermediate frequency signal to an in-phase and a quadrature phase by means of the pseudo-Noise code and spread spectrum data according to a quad-ature phase shift keying modulation method.
Patent
Fast power control in a variable data rate mobile cmda communication system
Edward G. Tiedemann,Tao Chen +1 more
TL;DR: In this article, a closed-loop power control method for variable rate transmissions is proposed for mobile communication systems, where the power of transmissions is varied in accordance with the rate of the frames of data being transmitted.
Patent
Method and apparatus for puncturing code symbols in a communications system
TL;DR: In this paper, a number of puncture distances, D1 through DN, are computed based on S and P, and a particular number of symbol punctures is determined for each computed puncture distance.
Patent
Code generating method and code selecting method
TL;DR: In this article, the authors propose a code generating method by combining an orthogonal code for CDMA having diffusivity larger than the original diffusivities of the original code by inverting the polarity of the orthogonality of the code.
References
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Book
Advanced Engineering Mathematics
TL;DR: This book discusses ODEs, Partial Differential Equations, Fourier Series, Integrals, and Transforms, and Numerics for ODE's and PDE's, as well as numerical analysis and potential theory, and more.
Patent
Spread spectrum multiple access communication using satellite or terrestrial repeaters
TL;DR: In this article, a multiple access, spread spectrum communication system and method for providing high capacity communications to, from, or between a plurality of system users, using code-division-spread-spectrum communication signals is presented.
Journal ArticleDOI
Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission
TL;DR: A class of nonlinear estimation algorithms is described to estimate the unknown phase of a carrier which is fully modulated by m -ary PSK modulation, and the effect of quantization and finite read-only-memory implementation of the nonlinearity are determined by computer simulation.