US 8,571,090 B2 · Technique for searching for a preamble signal in a spread spectrum using a fast hadamard transform

Abstract

In one embodiment, a method for demodulating and searching for a preamble signal containing a complex phasor signal is disclosed. The complex phasor is demodulated using a phasor-rotated fast transformer. A received signal is correlated with a spreading code to produce a correlated signal. The correlated signal is coherently accumulated to produce a coherently accumulated signal. A first phasor-rotated signal transformation is performed on a real component of the coherently accumulated signal, and a second phasor-rotated signal transformation is performed on an imaginary component of the coherently accumulated signal. Finally, the signal power of the transformed real and imaginary components of the coherently accumulated signal is determined.

Claims18

Dependent claims

A method for signal processing in a spread-spectrum communication system, comprising:

correlating a received signal with a spreading code to produce a correlated signal;
coherently accumulating the correlated signal to produce a coherently accumulated signal;
performing a first phasor-rotated signal transformation on a real component of the coherently accumulated signal;
performing a second phasor-rotated signal transformation on an imaginary component of the coherently accumulated signal;
and
determining signal powers of the transformed real and imaginary components of the coherently accumulated signal, wherein:
the received signal is a phasor-rotated signal;
and
the first and second phasor-rotated signal transformations perform phasor-derotation of the phasor-rotated signal.

6 more elements

A signal processor, comprising:

a correlation unit configured to correlate a received signal with a spreading code to produce a correlated signal;
a coherent accumulator configured to coherently accumulate the correlated signal to produce a coherently accumulated signal;
one or more transform processors configured to (i) perform a first phasor-rotated signal transformation on a real component of the coherently accumulated signal and (ii) perform a second phasor-rotated signal transformation on an imaginary component of the coherently accumulated signal;
and
an energy calculator configured to determine signal powers of the transformed real and imaginary components of the coherently accumulated signal, wherein:
the received signal is a phasor-rotated signal;
and
the first and second phasor-rotated signal transformations perform phasor-derotation of the phasor-rotated signal.

5 more elements

Dependencies are inferred from the claim text.

Technique for searching for a preamble signal in a spread spectrum using a fast hadamard transform

Life of this patent

Technique for searching for a preamble signal in a spread spectrum using a fast hadamard transform

Life of this patent

Abstract

Claims18