US 7,095,993 B2 · Frequency auto-correction apparatus for CDMA multipath fading channel

Abstract

An automatic frequency correction (AFC) apparatus used for CDMA multipath fading channels comprises a frequency-offset evaluator, an automatic frequency correction loop filter and a carrier frequency adjuster. The present invention provides a “multipath energy window” designing method for the non-determinacy of multipath signals in mobile communication environment. Frequency-offset information can be extracted from the multipath energy window by a simple calculation and evaluated by a maximal SNR weight process. This invention also provides a step-variable accumulation adjusting method and greatly improves the response speed of the AFC apparatus as compared with a conventional loop filter, whereby supplies better AFC required for CDMA mobile terminals.

Claims4

Dependent claims

A automatic frequency correction apparatus used for CDMA multipath fading channel comprises:

a frequency-offset evaluating means for extracting frequency-offset information from a multipath energy window and evaluating the frequency-offset value {overscore (Δω)}c by using maximal signal-noise ratio weight method;
an automatic frequency correction (AFC) loop filter for calculating a step δm of mth output based on the evaluated frequency-offset value and performing adaptive accumulating filtering on the calculated step δm;
and
a carrier frequency adjuster for making the local carrier frequency approach the carrier frequency value of the received signals gradually.

1 more element

Dependencies are inferred from the claim text.

Frequency auto-correction apparatus for CDMA multipath fading channel

Life of this patent

Frequency auto-correction apparatus for CDMA multipath fading channel

Life of this patent

Abstract

Claims4