Cryptographic system for wireless communications
First Claim
Patent Images
1. A base station in a spectrum wireless communications system, comprising:
- an RF antenna;
a reverse channel that receives and processes a signal from a wireless terminal; and
a forward channel that transmits an input signal from a mobile switching center to a wireless terminal, said forward channel circuit comprising;
a channel coder responsive to said mobile switching center that error correction codes said input signal,a bit interleaver responsive to said channel coder that rearranges the order of the bits in the input signal so as to minimize the effect of error bursts,an encryptor responsive to said channel coder that encrypts said input signal, said encryptor including a nonlinear scrambler for generating a key signal comprising a sequence of bits that have a nonlinear relationship to a private long code mask, andcircuitry responsive to said channel coder, said bit interleaver and said encryptor and coupled to said antenna for modulating and transmitting said input signal.
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Abstract
A wireless communications system (110) with increased privacy. The system (110) transmits an encrypted signal between a base station (112) and a wireless terminal (122). In the forward channel, the base station (112) includes an encryptor (130) with a nonlinear scrambler (202) that creates an key signal that has a nonlinear dependence on a long code mask M. The wireless terminal (122) similarly includes a decryptor (164) with a nonlinear scrambler (210) that creates a key signal that has a nonlinear dependence on the long code mask M.
55 Citations
55 Claims
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1. A base station in a spectrum wireless communications system, comprising:
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an RF antenna; a reverse channel that receives and processes a signal from a wireless terminal; and a forward channel that transmits an input signal from a mobile switching center to a wireless terminal, said forward channel circuit comprising; a channel coder responsive to said mobile switching center that error correction codes said input signal, a bit interleaver responsive to said channel coder that rearranges the order of the bits in the input signal so as to minimize the effect of error bursts, an encryptor responsive to said channel coder that encrypts said input signal, said encryptor including a nonlinear scrambler for generating a key signal comprising a sequence of bits that have a nonlinear relationship to a private long code mask, and circuitry responsive to said channel coder, said bit interleaver and said encryptor and coupled to said antenna for modulating and transmitting said input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. An encryptor for encrypting an input signal in a forward channel of a spread spectrum wireless communication system, said encryptor comprising:
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a long code generator that creams a long code sequence from a long code mask; a nonlinear scrambler responsive to said long code generator that creates a key signal that is a nonlinear function of the bits of the long code mask; and a combinational logic circuit that encrypts said input signal with said key signal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A wireless terminal for a spread spectrum wireless communication system, comprising;
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an RF antenna; a reverse channel circuit that processes and transmits a signal to a base station; and a forward channel circuit that receives and processes a transmitted signal from a base station, said forward channel circuit comprising; a receiver circuit coupled to said antenna that demodulates said transmitted signal, a decryptor responsive to said receiver circuit that decrypts said transmitted signal, said decryptor including a nonlinear scrambler for generating a key signal comprising a sequence of bits that have a nonlinear relationship to a private long code mask, a bit deinterleaver responsive to said receiver circuit that rearranges the order of the bits in the transmitted signal, a channel decoder responsive to said receiver circuit that utilizes error correction coding of said transmitted signal to provide error correction, a voice decoder responsive to said receiver circuit that generates an output signal from said transmitted signal, and an output device for outputting the transmitted signal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A method for preventing interception of an information signal from a spread spectrum base station to a wireless terminal in a wireless communications system, said method comprising the steps of:
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receiving an input signal from a mobile switching center; coding said input signal with a channel coder to provide error correction coding of said input signal; interleaving the bits of said input signal with a bit interleaver so as to minimize the effect of error bursts; generating a key signal with an encryptor including a nonlinear scrambler such that the bits of the key signal comprise a sequence of bits that have a nonlinear relationship to a private long code mask; encrypting said input signal with said key signal;
modulating said input signal for transmission; andtransmitting said input signal. - View Dependent Claims (38, 39, 40, 41, 42)
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43. A spread spectrum wireless infrastructure, comprising:
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a mobile switching center coupled to receive input signals from at least one local office and at least one toll office; a plurality of base stations coupled to said mobile switching center, each base station comprising; an RF antenna; a reverse channel that receives and processes a signal from a wireless terminal; and a forward channel that transmits an input signal from one of said mobile switching centers to a wireless terminal, said forward channel circuit comprising; a channel coder responsive to said mobile switching center that error correction codes said input signal, a bit interleaver responsive to said channel coder that rearranges the order of the bits in the input signal so as to minimize the effect of error bursts, an encryptor responsive to said channel coder that encrypts said input signal, said encryptor including a nonlinear scrambler for generating a key signal comprising a sequence of bits that have a nonlinear relationship to a private long code mask, and circuitry responsive to said channel coder and coupled to said antenna that modulates said input signal. - View Dependent Claims (44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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Specification