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
Correlation detectors for use in direct sequence spread spectrum signal receiver
TL;DR: In this paper, a plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different assigned code sequence shift, and each receiver includes a number of correlation detectors offset from each other by a fraction of a code chip together with decision circuitry to identify cross-correlation peaks for optimum synchronization.
Patent
Method and apparatus for reducing effects of multiple access interference in a radio receiver in a code division multiple access communication system
TL;DR: In this article, a CDMA system is disclosed which reduces the effects of multiple access interference, thus increasing channel capacity and achieving greater efficiency in the use of a given frequency bandwidth.
Patent
Spread spectrum communication system
TL;DR: In this article, a spread spectrum communication system has, in a transmission part, a first circuit for extracting a first carrier signal from a predetermined broadcase wave and generating a first clock signal by using the first carrier signals, a second circuit for generating first pseudo-noise signals by using first clock signals from the first circuit, and a third circuit for modulating an information signal and broadening a frequency band of the modulated information signal from the second circuit.
Patent
Direct-sequence spread-spectrum digital signal acquisition and tracking system and method therefor
Bruce M. Holland,Gary L. Bliss +1 more
TL;DR: In this article, a driect-sequence spread-spectrum TDMA (or TDD) digital communication is proposed, where the acquisition and tracking occurs for a plurality of frames having a predetermined number of time slots.
Patent
Anti-jam communications system
TL;DR: In this article, each binary message element, whether a binary "1" or a binary '0", alters successive portions of the pseudo-random binary bit sequence to create a modified pseudo random bit sequence, successive portions representing the binary information.