Method and apparatus for preamble synchronization in wireless radio frequency identification (RFID) systems
First Claim
1. A method for detecting a preamble portion of a signal, comprising:
- (a) receiving a plurality of samples in an input signal;
(b) counting samples that occur between consecutive sign changes in the received plurality of samples;
(c) performing step (b) a number of times to produce a sequence of counts of samples between consecutive sign changes in the received plurality of samples; and
(d) performing matched filtering of the sequence of counts of samples to determine whether a preamble is detected.
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Abstract
The present invention provides methods and apparatuses for detection of a preamble portion of a data packet. A plurality of samples are received in an input signal. Samples that occur between consecutive sign changes in the received plurality of samples are counted. The counting of samples is performed a number of times to produce a sequence of counts of samples between consecutive sign changes in the received plurality of samples. Matched filtering of the sequence of counts of samples is performed to determine whether a preamble is detected. Bit rate and timing are initialized for data decoding based on parameters of the sequence of sample counts of a detected preamble.
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Citations
28 Claims
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1. A method for detecting a preamble portion of a signal, comprising:
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(a) receiving a plurality of samples in an input signal;
(b) counting samples that occur between consecutive sign changes in the received plurality of samples;
(c) performing step (b) a number of times to produce a sequence of counts of samples between consecutive sign changes in the received plurality of samples; and
(d) performing matched filtering of the sequence of counts of samples to determine whether a preamble is detected. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for detecting a preamble portion of a signal, comprising:
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(a) receiving an in-phase signal component of an input signal having a first plurality of samples;
(b) counting samples that occur between consecutive sign changes in the received first plurality of samples;
(c) performing step (b) a number N of times to produce a first sequence of counts of samples between consecutive sign changes in the received first plurality of samples;
(d) performing matched filtering of the first sequence of counts of samples to generate a first preamble detection indication for the in-phase signal component;
(e) receiving a quadrature-phase signal component of the input signal having a second plurality of samples;
(f) counting samples that occur between consecutive sign changes in the received second plurality of samples;
(g) performing step (f) the number N of times to produce a second sequence of counts of samples between consecutive sign changes in the received second plurality of samples; and
(h) performing matched filtering of the second sequence of N counts of samples to generate a second preamble detection indication for the quadrature-phase signal component. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system in a receiver for detecting a preamble portion of a signal, comprising:
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a counter that counts samples that occur between consecutive sign changes in a plurality of samples received on an input signal;
a matched filter that includes a shift register of N registers, wherein an input register of the shift registers is coupled to an output of the counter, wherein the N registers store a sequence of N sample counts received from the counter;
N gates that are coupled to the N registers, wherein each gate of the N gates determines whether a sample count of a corresponding register of the N registers is within a predetermined range; and
a logical AND that receives an output determination signal from each gate and generates a preamble detection indication. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A system in a receiver for detecting a preamble portion of a signal, comprising:
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a first counter that counts samples that occur between consecutive sign changes in a plurality of samples received on an in-phase signal component of an input signal;
a first matched filter that includes a first shift register having N registers, wherein an input register of the first shift register is coupled to an output of the first counter, wherein the N registers of the first shift register store a first sequence of N samples counts received from the first counter;
a first N gates that are coupled to the N registers of the first shift register, wherein each gate of the first N gates determines whether a sample count of a corresponding register of the N registers of the first shift register is within a predetermined range;
a first logical AND that receives a determination signal from each gate of the first N gates and generates a first preamble detection indication;
a second counter that counts samples that occur between consecutive sign changes in a plurality of samples received on an quadrature-phase signal component of the input signal;
a second matched filter that includes a second shift register having N registers, wherein an input register of the second shift register is coupled to an output of the second counter, wherein the N registers of the second shift register store a second sequence of N samples counts received from the second counter;
a second N gates that are coupled to the N registers of the second shift register, wherein each gate of the second N gates determines whether a sample count of a corresponding register of the N registers of the second shift register is within a predetermined range; and
a second logical AND that receives a determination signal from each gate of the second N gates and generates a second preamble detection indication. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification