Preamble detection using low-complexity cross-correlation
First Claim
1. A system, comprising:
- a differential demodulation module that (i) differentially demodulates modulated signals and (ii) generates corresponding differentially demodulated signals; and
a cross-correlation module thatreceives said differentially demodulated signals,generates cross-correlation values by cross-correlating states of X symbols in said differentially demodulated signals with corresponding states of X predetermined symbols in each of Y preamble sequences, anddetermines whether one of said Y preamble sequences is present in said modulated signals based on said cross-correlation values, where X and Y are integers greater than 1, andwherein said cross-correlation module comprises;
a state detection module that detects said states of said X symbols in said differentially demodulated signals, where each of said X symbols has one of a first state and a second state; and
a summing module that (i) receives said Y preamble sequences and (ii) generates said cross-correlation values by generating X sums for each of said Y preamble sequences by adding each of said states of said X symbols with said corresponding states of said X predetermined symbols in each of said Y preamble sequences.
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Abstract
A system includes a differential demodulation module that differentially demodulates modulated signals. A cross-correlation module generates cross-correlation values by cross-correlating states of X symbols in the differentially demodulated signals with corresponding states of X predetermined symbols in each of Y preamble sequences, and determines whether one of the Y preamble sequences is present in the modulated signals, where X and Y are integers greater than 1. The cross-correlation module includes a state detection module that detects the states of the X symbols in the differentially demodulated signals, where each of the X symbols has one of a first state and a second state, and a summing module that generates the cross-correlation values by generating X sums for each of the Y preamble sequences by adding each of the states of the X symbols with the corresponding states of the X predetermined symbols in each of the Y preamble sequences.
43 Citations
46 Claims
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1. A system, comprising:
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a differential demodulation module that (i) differentially demodulates modulated signals and (ii) generates corresponding differentially demodulated signals; and a cross-correlation module that receives said differentially demodulated signals, generates cross-correlation values by cross-correlating states of X symbols in said differentially demodulated signals with corresponding states of X predetermined symbols in each of Y preamble sequences, and determines whether one of said Y preamble sequences is present in said modulated signals based on said cross-correlation values, where X and Y are integers greater than 1, and wherein said cross-correlation module comprises; a state detection module that detects said states of said X symbols in said differentially demodulated signals, where each of said X symbols has one of a first state and a second state; and a summing module that (i) receives said Y preamble sequences and (ii) generates said cross-correlation values by generating X sums for each of said Y preamble sequences by adding each of said states of said X symbols with said corresponding states of said X predetermined symbols in each of said Y preamble sequences. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method, comprising:
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generating differentially demodulated signals by differentially demodulating modulated signals using a differential demodulator, wherein said modulated signals include sub-carriers that are modulated using orthogonal frequency domain multiplexing (OFDM); detecting states of X symbols in said differentially demodulated signals, where each of said X symbols has one of a first state and a second state, and X is an integer greater than 1; generating cross-correlation values by cross-correlating said states of said X symbols in said differentially demodulated signals with corresponding states of X predetermined symbols in each of Y preamble sequences, where Y is an integer greater than 1, wherein said cross-correlation values are generated by generating X sums for each of said Y preamble sequences by adding each of said states of said X symbols with said corresponding states of said X predetermined symbols of each of said Y preamble sequences, where said X sums are modulo-2 sums; and determining whether one of said Y preamble sequences is present in said modulated signals based on said cross-correlation values. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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Specification