System and method for generating signal waveforms in a CDMA cellular telephone system
First Claim
1. In a direct sequence spread spectrum modulator, a signal orthogonalizer comprising:
- pilot channel signal generator means for generating a pilot signal according to a first orthogonal function; and
communication channel signal generator means for receiving an input information signal, generating an orthogonal function signal according to a second orthogonal function, combining said orthogonal function signal with said input information signal to provide a resultant communication channel signal.
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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 signalling along with QPSK spreading.
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Citations
45 Claims
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1. In a direct sequence spread spectrum modulator, a signal orthogonalizer comprising:
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pilot channel signal generator means for generating a pilot signal according to a first orthogonal function; and communication channel signal generator means for receiving an input information signal, generating an orthogonal function signal according to a second orthogonal function, combining said orthogonal function signal with said input information signal to provide a resultant communication channel signal. - View Dependent Claims (2, 3, 4, 5)
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6. A communication system modulation system comprising:
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pilot channel signal generator means for generating as a pilot signal a first orthogonal function signal according to a first orthogonal function selected from a set of Walsh functions; communication channel signal generator means for receiving an input information signal, generating a second orthogonal function signal according to a second orthogonal function selected from said set of Walsh functions wherein said second orthogonal function is different from said first orthogonal function, combining said second orthogonal function signal with said input information signal and providing a resultant communication signal; and spreading means for receiving said pilot signal and said communication signal, generating a pseudorandom noise (PN) signal of a predetermined PN code, combining said PN signal with each of said pilot signal and said communication signal to produce corresponding PN spread pilot and communication signals. - View Dependent Claims (7, 8)
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9. A communication system modulation system comprising:
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a pseudorandom noise (PN) generator having an output wherein said PN generator generates and provides at said PN generator output a PN signal of a predetermined PN code; a pilot channel signal generator having an output wherein said pilot signal generator provides at said pilot channel signal generator output a pilot signal according to a first Walsh function from a set of Walsh functions; at least one system channel signal generator each having an input and an output, wherein each system channel signal generator receives at said respective system channel signal generator input a respective system information signal and provides at said respective system channel signal generator output a respective system channel signal representative of each respective system information signal orthogonalized according to a respectively different Walsh function from a first subset of Walsh functions of said set of Walsh functions exclusive of said first Walsh function; at least one user channel signal generator each having an input and an output, wherein each user channel signal generator receives at said respective user channel signal generator input a respective user information signal and provides at said respective user channel signal generator output a user channel signal representative of each respective user information signal orthogonalized according to a respectively different Walsh function selected from a second subset of Walsh functions of said set of Walsh functions exclusive of said first Walsh function and said first subset of Walsh functions; and a combining circuit having a plurality of inputs and an output, each combining circuit input coupled to a respective one of said PN generator output, said pilot channel signal generator output, each of said system channel signal generator outputs and each of said user channel signal generator outputs, wherein said combining circuit combines said PN signal with said pilot channel signal, each of said system channel signals and each of said user channel signals and provides corresponding PN spread signals at said combining circuit output. - View Dependent Claims (10, 11)
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12. In a direct sequence spread spectrum communications modulator in which a plurality of input signals to be transmitted are bandwidth spread according to a predetermined pseudorandom noise spreading code, a method for orthogonalizing said input signals comprising the steps of:
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generating a plurality of orthogonal function signals; and modulating each of said channel signals with a different one of said orthogonal function signals. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A modulation method for direct sequence spread spectrum communications comprising the steps of:
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generating a plurality of orthogonal function signals; and receiving at least one input information signal; modulo-2 adding each of said information signals with a different one of said orthogonal function signals to provide orthogonalized information signals; generating a predetermined pseudorandom noise spreading code; and modulo-2 adding each of said orthogonalized information signals with said pseudorandom noise spreading code to provide bandwidth spread orthogonalized information signals. - View Dependent Claims (19, 20, 21)
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22. In a communication system in which a plurality of remote user stations communicate, via a radio link with a base station, with other user stations, said base station having a base station transceiver for communicating user station information signals to intended recipient remote user stations and for receiving remote user station communicated information signals for transfer to intended recipient user stations, said base station transceiver comprising:
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base station transmission means for receiving at least one user station information signal, orthogonalizing each received user station information signal according to a respective predetermined orthogonal function, bandwidth spreading and transmitting said orthogonalized user station information signals as a base station communication signal; and base station reception means for receiving and extracting from each remote user station transmitted remote user station communication signal a corresponding remote user station information signal for transfer to intended recipient user stations. - View Dependent Claims (23, 24, 25, 26)
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27. A communication system in which a plurality of remote user stations communicate, via a radio link with a base station, with other user stations, said base station having a base station transceiver for communicating user station information signals to intended recipient remote user stations and for receiving remote user station communicated information signals destined for intended recipient user stations, said base station transceiver comprising:
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base station transmitter means for generating a plurality of orthogonal function signals wherein one of said orthogonal functions signals is a pilot signal, receiving at least one user station information signal each intended for a recipient remote user station, combining each received user station information signal with a respective another one of said plurality of orthogonal function signals to produce corresponding resultant base station intermediate signals, generating a base station first pseudorandom noise (PN) signal of a first predetermined PN code, combining said base station first PN signal with each of said pilot and base station intermediate signals to produce corresponding base station PN spread pilot and base station intermediate signals, modulating said base station PN spread pilot and base station intermediate signals upon a base station carrier signal and transmitting said modulated base station carrier signal as a base station communication signal; and base station receiver means for receiving and extracting from each remote user station transmitted remote user station communication signal a corresponding remote user station information signal. - View Dependent Claims (28, 29, 30, 31, 32, 33)
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34. A communication system in which a plurality of remote user stations communicate with other user stations, via a radio link with a base station, said communication system comprising:
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a base station having base station transmission means for communicating user station information signals to intended recipient remote user stations, said base station transmission means comprising; (a) pilot channel signal generator means for generating as a pilot signal an orthogonal function signal according to a first Walsh function selected from a set of Walsh functions; (b) at least one communication channel signal generator means each for receiving a respective user station information signal each intended for a different one of said remote user stations, generating an additional Walsh function signal according to an additional Walsh function selected from said set of Walsh functions wherein each additional Walsh function is different from said first Walsh function, combining each additional Walsh function signal with said respective user station information signal to produce a respective communication channel signal; (c) base station spreading means for receiving said pilot signal and each communication channel signal, generating a base station pseudorandom noise (PN) signal of a first predetermined PN code, combining said PN signal with each of said pilot channel and communication channel signals to produce corresponding base station PN spread pilot and communication signals; and (d) base station transmission means for receiving and modulating said base station PN spread pilot and communication channel signals upon a base station carrier signal and transmitting said modulated base station carrier signal as a base station communication signal; said base station having base station reception means for receiving and extracting from each remote user station transmitted remote user station communication signal a corresponding remote user station information signal destined for intended recipient user stations; at least one remote user station each having remote user station transmission means for communicating remote user station information signals to said base station, said remote user station transmission means comprising; (a) orthogonal function encoder means for, receiving an input remote user station information signal, converting sequential portions of said input signal into respective Walsh function signal portions wherein each Walsh function signal portion is according to a Walsh function selected from a plurality of Walsh functions according to a value of said respective portions of said input remote user station information signal, and providing an output of said Walsh functions functions function signal portions; (b) remote user station spreading means for, receiving each of said Walsh function signal portions, generating a remote user station pseudorandom noise (PN) signal of a second predetermined PN code, combining said Walsh function signal portions with said remote user station PN signal so as to produce a remote user station PN spread signal; and (c) remote user station transmission means for receiving and modulating said remote user station PN spread signal upon a remote user station carrier signal and transmitting said modulated remote user station carrier signal as a remote user station communication signal; and said at least one remote user station each having remote user station reception means for receiving and extracting from said base station communication signal said user station information signal intended for each respective remote user station. - View Dependent Claims (35, 36, 37, 38, 39)
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40. A communication system modulator comprising:
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means for generating a plurality of orthogonal function signals; and means for combining a plurality of input information signals with a different one of said orthogonal function signals to provide a plurality of orthogonalized information signals; means for generating a common pseudorandom noise (PN) signal; means for combining each orthogonalized information signals with said common PN signal to provide respective bandwidth spread orthogonalized information signals. - View Dependent Claims (41, 42, 43, 44, 45)
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Specification