Spread spectrum multipath combining subsystem and method
First Claim
1. A multipath-combining subsystem for use with a spread-spectrum receiver for receiving a spread-spectrum signal arriving at different times from a plurality of paths, with the spread-spectrum signal having a plurality of packets with each packet having a header followed by a data portion, with the header including a header-chip-sequence signal, and with the data portion including a data-symbol-sequence signal, with each data symbol of the data-symbol-sequence signal spread-spectrum processed by a data-chip-sequence signal, said multipath-combining subsystem comprising:
- matched-filter means, coupled to said spread-spectrum receiver, having a first impulse response matched to the header-chip-sequence signal of the header embedded in the spread-spectrum signal, for detecting, within a packet and for each path of the spread-spectrum signal, each match of the header-chip-sequence signal with the first impulse response, with a time difference between receiving each path of the spread-spectrum signal greater than a time of each chip of the header-chip-sequence signal and greater than a time of each chip of the data-chip-sequence signal, and for outputting, responsive to a detected match having a correspondence between the header-chip-sequence signal and the first impulse response above a header threshold, a header detection signal having a header amplitude and a respective chip location;
header-memory means, coupled to said matched-filter means, for storing the header amplitude of each header-detection signal and the respective chip location of each header-detection signal;
said matched-filter means having a second impulse response matched to the data-chip-sequence signal of the data portion embedded in the spread-spectrum signal, for detecting, at the respective chip location of each header-detection signal for each path, each match of the data-chip-sequence signal with the second impulse response, and for outputting, responsive to each detected match, a data-detection signal having a data amplitude; and
combining means, coupled to said header-memory means and to said matched-filter means, for multiplying the header amplitude of each header-detection signal by the data amplitude of each data-detection signal at each corresponding chip location, respectively, thereby generating a plurality of weighted elements for each data symbol within the data portion, and for combining the plurality of weighted elements of a respective data symbol as a sum signal of the respective data symbol.
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Abstract
A multipath-combining subsystem for receiving a spread-spectrum signal arriving from a plurality of paths. A header-matched filter detects each match, within each path, of a header-chip-sequence signal with a first impulse response and outputs a header-detection signal having a header amplitude and a respective chip location. A data-matched filter detects at the respective chip location of each header-detection signal, a respective data-chip-sequence signal and outputs a data-detection signal having a data amplitude. A combiner multiplies the header amplitude of each header-detection signal and the data amplitude of the respective data symbol to generate a plurality of weighted elements for each data symbol. The combiner then adds the plurality of weighted elements for each data symbol as a sum signal of the respective data symbol.
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Citations
16 Claims
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1. A multipath-combining subsystem for use with a spread-spectrum receiver for receiving a spread-spectrum signal arriving at different times from a plurality of paths, with the spread-spectrum signal having a plurality of packets with each packet having a header followed by a data portion, with the header including a header-chip-sequence signal, and with the data portion including a data-symbol-sequence signal, with each data symbol of the data-symbol-sequence signal spread-spectrum processed by a data-chip-sequence signal, said multipath-combining subsystem comprising:
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matched-filter means, coupled to said spread-spectrum receiver, having a first impulse response matched to the header-chip-sequence signal of the header embedded in the spread-spectrum signal, for detecting, within a packet and for each path of the spread-spectrum signal, each match of the header-chip-sequence signal with the first impulse response, with a time difference between receiving each path of the spread-spectrum signal greater than a time of each chip of the header-chip-sequence signal and greater than a time of each chip of the data-chip-sequence signal, and for outputting, responsive to a detected match having a correspondence between the header-chip-sequence signal and the first impulse response above a header threshold, a header detection signal having a header amplitude and a respective chip location; header-memory means, coupled to said matched-filter means, for storing the header amplitude of each header-detection signal and the respective chip location of each header-detection signal; said matched-filter means having a second impulse response matched to the data-chip-sequence signal of the data portion embedded in the spread-spectrum signal, for detecting, at the respective chip location of each header-detection signal for each path, each match of the data-chip-sequence signal with the second impulse response, and for outputting, responsive to each detected match, a data-detection signal having a data amplitude; and combining means, coupled to said header-memory means and to said matched-filter means, for multiplying the header amplitude of each header-detection signal by the data amplitude of each data-detection signal at each corresponding chip location, respectively, thereby generating a plurality of weighted elements for each data symbol within the data portion, and for combining the plurality of weighted elements of a respective data symbol as a sum signal of the respective data symbol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A multipath-combining subsystem for use with a spread-spectrum receiver for receiving a spread-spectrum signal arriving at different times from a plurality of paths, with the spread-spectrum signal having a plurality of packets with each packet having a header followed by a data portion, with the header including a header-chip-sequence signal, and with the data portion including a data-symbol-sequence signal, with each data symbol of the data-symbol-sequence signal spread-spectrum processed by a data-chip-sequence signal, said multipath-combining subsystem comprising:
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a header-matched filter, coupled to said spread-spectrum receiver, having a first impulse response matched to the header-chip-sequence signal of the header embedded in the spread-spectrum signal, for detecting, within a packet and for each path of the spread-spectrum signal, each match of the header-chip-sequence signal with the first impulse response, with a time difference between receiving each path of the spread-spectrum signal greater than a time of each chip of the header-chip-sequence signal and greater than a time of each chip of the data-chip-sequence signal, and for outputting, responsive to a detected match having a correspondence between the header-chip-sequence signal and the first impulse response above a header threshold, a header detection signal having a header amplitude and a respective chip location; a header memory, coupled to said header-matched filter, for storing the amplitude and the respective chip location of each header-detection signal; a symbol-matched filter, having a second impulse response matched to the data-chip-sequence signal of the data portion embedded in the spread-spectrum signal, for detecting, at the respective chip location of each header-detection signal for each path, each match of the data-chip-sequence signal with the second impulse response, and for outputting, responsive to each detected match, a data-detection signal having a data amplitude; a header-timing circuit, coupled to an output of said header-matched filter, for detecting, from a plurality of header-detection signals, a strongest header-detection signal and, responsive to the strongest header-detection signal, for outputting a packet-start signal; product means, coupled to an output of said header-matched filter and to an output of said header-timing circuit, for multiplying the header amplitude of each header-detection signal by the data amplitude of each data-detection signal at each corresponding chip location, respectively, thereby generating a plurality of weighted elements for each data symbol of the data-symbol-sequence signal within the data portion of the packet; adding means, coupled to an output of said product means, for adding the plurality of weighted elements for a respective data symbol to generate a sum signal of the respective data symbol; a combiner memory, coupled to an output of said adding means, for storing the sum signal; and a data demodulator, coupled to said combiner memory, for detecting data from the sum signal.
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11. A multipath-combining subsystem for use with a spread-spectrum receiver for receiving a spread-spectrum signal arriving at different times from a plurality of paths, with the spread-spectrum signal having a plurality of packets with each packet having a header followed by a data portion, with the header including a header-chip-sequence signal, and with the data portion including a data-symbol-sequence signal, with each data symbol of the data-symbol-sequence signal spread-spectrum processed by a data-chip-sequence signal, said multipath-combining subsystem comprising:
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a programmable-matched filter, coupled to said spread-spectrum receiver, having a first impulse response matched to the header-chip-sequence signal of the header embedded in the spread-spectrum signal, for detecting, within a packet and for each path of the spread-spectrum signal, each match of the header-chip-sequence signal with the first impulse response, with a time difference between receiving each path of the spread-spectrum signal greater than a time of each chip of the header-chip-sequence signal and greater than a time of each chip of the data-chip-sequence signal, and for outputting, responsive to each detected match above a header threshold, a header detection signal having a header amplitude and a respective chip location; a header memory, coupled to said programmable-matched filter, for storing the header amplitude and the respective chip location of each header-detection signal; a header-timing circuit, coupled to an output of said programmable-matched filter, for detecting, from a plurality of header-detection signals, a strongest header-detection signal and, responsive to the strongest header-detection signal, for outputting a packet-start signal; said programmable-matched filter, responsive to the packet-start signal, for changing the first impulse response to a second impulse response, the second impulse response matched to the data-chip-sequence signal of the data portion embedded in the spread-spectrum signal, for detecting, at the respective chip location of each header-detection signal for each path, each match of the data-chip-sequence signal with the second impulse response, and for outputting, responsive to each detected match, a data-detection signal having a data amplitude; product means, coupled to an output of said programmable-matched filter and to an output of said header-timing circuit, for multiplying the header amplitude of each header-detection signal by the data amplitude of each data-detection signal at each corresponding chip location, respectively, thereby generating a plurality of weighted elements for each data symbol of the data-symbol-sequence signal within the data portion of the packet; adding means, coupled to an output of said product means, for adding the plurality of weighted elements for a respective data symbol to generate a sum signal of the respective data symbol; a combiner memory, coupled to an output of said adding means, for storing the sum signal; and a data demodulator, coupled to said combiner memory, for detecting data from the sum signal.
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12. A multipath-combining method for use with a spread-spectrum receiver for receiving a spread-spectrum signal arriving at different times from a plurality of paths, with the spread-spectrum signal having a plurality of packets with each packet having a header followed by a data portion, with the header including a header-chip-sequence signal, and with the data portion including a data-symbol-sequence signal, with each data symbol of the data-symbol-sequence signal spread-spectrum processed by a data-chip-sequence signal, said multipath-combining method comprising the steps of:
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a. detecting, with a first impulse response matched to the header-chip-sequence signal of the header embedded in the spread-spectrum signal, within a packet and for each path, each match of the header-chip-sequence signal with the first impulse response, with a time difference between receiving each path of the spread-spectrum signal greater than a time of each chip of the header-chip-sequence signal; b. outputting, in response to each detected match above a header threshold, a header-detection signal having a header amplitude and a respective chip location; c. storing the header amplitude and the respective chip location of each header-detection signal; d. detecting, with a second impulse response matched to the data-chip-sequence signal embedded in the data portion of the spread-spectrum signal, at the respective chip location of each header-detection signal for each path, each match of the data-chip-sequence signal with the second impulse response; e. outputting, responsive to each detected match, a data-detection signal having a data amplitude; f. multiplying the header amplitude of each header-detection signal with the data amplitude of each data-detection-signal at each corresponding chip location, respectively, thereby generating a plurality of weighted elements for each data symbol of the data-symbol-sequence signal; and g. adding the plurality of weighted elements for a respective data symbol as a sum signal of the respective data symbol. - View Dependent Claims (13, 14, 15, 16)
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Specification