All digital maximum likelihood based spread spectrum receiver
First Claim
1. A spread spectrum receiver for use in a spread spectrum communication system, said spread spectrum receiver comprising:
- an analog-to-digital converter for receiving an analog spread spectrum signal, and for converting said received analog signal to a digital signal, said received analog signal having a plurality of both main and multipath return signals of varying signal strengths;
a frequency offset correction device, electrically connected to said analog-to-digital converter, for modifying said digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in said received analog signal;
searching means for receiving said modified digital signal, and for searching through said modified digital signal to identify M of said main and multipath return signals having the strongest signal strengths; and
processing means, electrically connected to said searching means and said frequency offset correction device, for processing said identified main and multipath return signals in accordance with predetermined maximum likelihood techniques to thereby generate said frequency correction term signal.
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Abstract
A spread spectrum receiver for use in spread spectrum communication systems is disclosed. The spread spectrum receiver of the present invention includes an analog-to-digital converter for receiving an analog spread spectrum signal, and for converting the received analog signal to a digital signal. The spread spectrum receiver also includes a digital frequency offset correction device, for modifying the digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in the received analog signal. The spread spectrum receiver also contains a Rake receiver. The spread spectrum receiver searches through the modified digital signal to identify M of the main and multipath return signals having the strongest signal strengths. The identified main and multipath return signals are processed in accordance with predetermined maximum likelihood techniques to thereby generate phase correction and maximal-ratio combining weighting factors for each of the M signals, as well as the overall frequency correction term signal.
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Citations
10 Claims
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1. A spread spectrum receiver for use in a spread spectrum communication system, said spread spectrum receiver comprising:
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an analog-to-digital converter for receiving an analog spread spectrum signal, and for converting said received analog signal to a digital signal, said received analog signal having a plurality of both main and multipath return signals of varying signal strengths; a frequency offset correction device, electrically connected to said analog-to-digital converter, for modifying said digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in said received analog signal; searching means for receiving said modified digital signal, and for searching through said modified digital signal to identify M of said main and multipath return signals having the strongest signal strengths; and processing means, electrically connected to said searching means and said frequency offset correction device, for processing said identified main and multipath return signals in accordance with predetermined maximum likelihood techniques to thereby generate said frequency correction term signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of receiving spread spectrum signals, comprising the steps of:
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(a) receiving an analog spread spectrum signal having a plurality of both main and multipath return signals of varying signal strengths; (b) converting said received analog signal to a digital signal; (c) modifying said digital signal in accordance with a frequency correction term signal to thereby correct for frequency offset in said received analog signal; (d) searching through said modified digital signal to identify M of said main and multipath return signals having the strongest signal strengths; and (e) processing said identified main and multipath return signals in accordance with predetermined maximum likelihood techniques to thereby generate said frequency correction term signal. - View Dependent Claims (9, 10)
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Specification