Method for amplitude insensitive packet detection
First Claim
1. In a digital wireless receiver, a method of detecting the presence of a data packet in a received radio frequency (RF) signal comprising the steps of:
- (a) down-converting said RF signal into in-phase (I) and quadrature (Q) baseband signals;
(b) removing direct current (DC) offsets from said I and Q baseband signals;
(c) modulating said I and Q baseband signals;
(d) performing amplitude normalization on said modulated I and Q baseband signals;
(e) comparing said amplitude normalized I and Q baseband signals to a reference signal via a complex correlator;
(f) detecting a peak of said complex correlator output; and
(g) if said peak is above a predefined threshold, indicating that a data packet has been received, else performing steps (a) to (g) on a subsequently received RF signal.
3 Assignments
0 Petitions
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.
-
Citations
18 Claims
-
1. In a digital wireless receiver, a method of detecting the presence of a data packet in a received radio frequency (RF) signal comprising the steps of:
-
(a) down-converting said RF signal into in-phase (I) and quadrature (Q) baseband signals;
(b) removing direct current (DC) offsets from said I and Q baseband signals;
(c) modulating said I and Q baseband signals;
(d) performing amplitude normalization on said modulated I and Q baseband signals;
(e) comparing said amplitude normalized I and Q baseband signals to a reference signal via a complex correlator;
(f) detecting a peak of said complex correlator output; and
(g) if said peak is above a predefined threshold, indicating that a data packet has been received, else performing steps (a) to (g) on a subsequently received RF signal. - View Dependent Claims (2, 3, 4, 5, 6, 14)
-
-
7. In a wireless digital receiver, a circuit for detecting the presence of a data packet in a received radio frequency (RF) signal comprising:
-
(a) a direct current (DC) offset module to correct for local oscillator (LO) leakage in in-phase (I) and quadrature (Q) baseband signals derived from said received RF signal;
(b) an acquisition module communicating with said DC offset module comprising i. a M-ary phase shift keying (PSK) mapper for mapping said I and Q baseband signals to a quantized PSK signal constellation;
ii. a complex correlator receiving input from said M-ary PSK mapper for comparing said mapped I and Q baseband signals to a reference; and
iii. a detector receiving input from said complex correlator for determining the presence of a correct signature. - View Dependent Claims (8, 9, 18)
-
-
10. In a wireless digital receiver, a method for detecting the presence of a data packet in a received quadrature amplitude modulated (QAM) radio frequency (RF) signal comprising mapping said QAM RF signal to a quantized phase shift keying (PSK) constellation;
- and processing in a matched complex correlator to detect the presence of a data packet.
- View Dependent Claims (11, 12, 13)
-
15. In a wireless digital receiver, a circuit for detecting the presence of a data packet in a received radio frequency (RF) signal (a) a direct current (DC) offset module to correct for local oscillator (LO) leakage in in-phase (I) and quadrature (Q) baseband signals derived from said received RF signal;
- and (b) an acquisition module receiving said corrected I and Q baseband signals for performing mapping, comparing and detecting functions in relation thereto to determine the presence of information bits associated with said data packet.
- View Dependent Claims (16, 17)
Specification