Method for amplitude insensitive packet detection
First Claim
1. A method, comprising:
- converting a radio frequency (RF) signal into in-phase (I) and quadrature (Q) baseband signals;
removing direct current (DC) offsets from the I and Q baseband signals to generate I and Q corrected signals;
mapping the I and Q corrected signals to a quadrature phase shift keying (QPSK) constellation to generate mapped I and Q baseband signals;
using a complex correlator to correlate the mapped I and Q baseband signals to a reference signal to generate complex correlated I and Q baseband signals; and
determining receipt of a data packet in the RF signal responsive to at least a portion of the complex correlated I and Q baseband signals exceeding a predetermined threshold.
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Accused Products
Abstract
The invention relates generally to the field of wireless communications and more particularly to a method of and device for detecting the presence of a received data packet in a digital receiver. The present invention proposes a simplified method of correlation by removing dependency on the amplitude fluctuations while at the same time maintaining phase relevancy. The key advancement involves mapping the complex quadrature amplitude modulation (QAM) preamble to a quantized phase shift keying (PSK) constellation before application to a matched complex correlator. The proposed process essentially “amplitude normalizes” the input signal without the use or complexity associated with a divider. This simplified normalization scheme makes the packet detection algorithm robust against amplitude variations in the input signal, while still allowing for good correlation output. In applications where interference is superimposed on the I/Q input signals, the invention improves the detection capability over automatic gain control (AGC) normalization methods.
33 Citations
23 Claims
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1. A method, comprising:
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converting a radio frequency (RF) signal into in-phase (I) and quadrature (Q) baseband signals; removing direct current (DC) offsets from the I and Q baseband signals to generate I and Q corrected signals; mapping the I and Q corrected signals to a quadrature phase shift keying (QPSK) constellation to generate mapped I and Q baseband signals; using a complex correlator to correlate the mapped I and Q baseband signals to a reference signal to generate complex correlated I and Q baseband signals; and determining receipt of a data packet in the RF signal responsive to at least a portion of the complex correlated I and Q baseband signals exceeding a predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus, comprising:
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means for converting a radio frequency (RF) signal into in-phase (I) and quadrature (Q) baseband signals; means for removing direct current (DC) offsets from the I and Q baseband signals to generate corrected I and Q baseband signals; means for mapping the corrected I and Q baseband signals to a quadrature phase shift keying (QPSK) constellation to generate mapped I and Q baseband signals; means for complex correlating the mapped I and Q baseband signals to a reference signal to generate complex correlated I and Q baseband signals; and means for determining receipt of a data packet in the RF signal responsive to at least a portion of the complex correlated I and Q baseband signals exceeding a predetermined threshold. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An apparatus, comprising:
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a down-converter configured to convert a radio frequency (RF) signal at least into in-phase (I) and quadrature (Q) baseband signals; a direct current (DC) offset module configured to remove DC offsets from the I and Q baseband signals to generated corrected I and Q baseband signals; a mapper configured to generate mapped I and Q baseband signals by mapping the corrected I and Q baseband signals to a quadrature phase shift keying (QPSK) constellation; a complex correlator configured to generate complex correlated I and Q baseband signals by correlating the mapped I and Q baseband signals to a reference signal; and a detector configured to detect at least one data packet in the RF signal according to at least a portion of the complex correlated I and Q baseband signals exceeding a predetermined threshold. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A wireless receiver, comprising:
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a converter configured to convert a radio frequency signal (RF) into in-phase (I) and quadrature (Q) baseband signals; an offset module configured to remove direct current (DC) offsets from the I and Q baseband signals to generate I and Q corrected signals; a phase shift keying (PSK) mapper configured to map I and Q corrected to a quantized phase shift keying (QPSK) constellation; a complex correlator configured to compare the mapped I and Q baseband signals to a reference to thereby generate complex correlated I and Q baseband signals; and a detector configured to detect a signature in the RF signal responsive to to at least a portion of the complex correlated I and Q baseband signals. - View Dependent Claims (22, 23)
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Specification