US 7,688,878 B2 · Method and device of peak detection in preamble synchronization for direct sequence spread spectrum communication

Abstract

A spread-spectrum preamble synchronization peak detection system performs multiple statistical tests based on instant and time-averaged channel condition measurements to identify the synchronization peak. In a normalized peak-to-average test, a peak-to-average ratio measurement is normalized by a signal-to-noise ratio measurement to form a new statistical measure which effectively eliminates the impact of the wide dynamic range of the signal-to-noise ratio of the received samples. A transition SNR test is used to eliminate potential false alarms caused by spurious PARN peaks during the transition period at the onset of preamble arrival. Code-phase aligned time-averaging is used to estimate the signal and noise levels over a sliding window. The code-phase alignment of samples effectively separates signal and noise samples in the averaging process, and resulting in more accurate signal and noise measurements. In estimating noise levels, the system takes multi-path interference into account by excluding both the peak signal and the side-lobe signals caused by multi-path wireless channels, resulting in more accurate estimation of noise level.

Claims16

Dependent claims

An apparatus for detecting a preamble in a burst-type spread-spectrum communications system, the device comprising:

means for determining channel signal and noise features;
means for performing a normalized peak-to-average ratio (PARN) test using the channel signal and noise features, wherein the means for performing the PARN test includes means for determining an outer code matched filter peak-to-average output value, means for normalizing said value by a time-averaged signal-to-noise ratio, and means for comparing said normalized peak-to-average ratio against a threshold value;
means for performing a transition signal-to-noise ratio (SNR) test using the channel signal and noise features, wherein the means for performing the transition SNR test includes means for determining a ratio between an instant and a delayed time-averaged signal-to-noise ratio and comparing said ratio between an instant and a delayed time-averaged signal-to-noise ratio against a threshold value;
and
means for generating a preamble detection indication if the PARN test and the transition SNR test pass, wherein generating the preamble detection indication is disabled during a transition period at an onset of an arrival of the preamble.

2 more elements

Dependencies are inferred from the claim text.

Method and device of peak detection in preamble synchronization for direct sequence spread spectrum communication

Life of this patent

Method and device of peak detection in preamble synchronization for direct sequence spread spectrum communication

Life of this patent

Abstract

Claims16