Importance

Loading Importance Indicators...

Abstract

An improvement for a method and system for tracking a spreading code, used in a code division multiple access (CDMA) system. An input signal has spread-spectrum modulation. The spreading code embedded in the spread-spectrum modulation has a plurality of chips. The input signal is sampled, and half-chip offset samples are formed from the sampled input signal. An even set of the half-chip offset samples are grouped into an early set of samples, and an odd set of the half-chip offset samples are grouped into a late set of samples. Each early set of samples is multiplied by spreading codes c(n+1), c(n+2), . . . , c(n+L), to generate a first plurality of products. L is approximately equal to the number of chips of delay between the earliest and latest multipath signals. A first plurality of sums and magnitudes are computed from the first plurality of products. The first plurality of magnitudes are multiplied by a first plurality of weights, to generate a first plurality of weighted-signal values. The first plurality of weighted-signal values are summed to generate an early signal-energy value. Each late set of samples is multiplied by spreading codes c(n-1), c(n-2), . . . , c(n-L), to generate a second plurality of products. A second plurality of sums and magnitudes are computed from the second plurality of products. The second plurality of magnitudes are multiplied by a second plurality of weights, to generated a second plurality of weighted-signal values. The second plurality of weighted-signal values are summed to generate a late signal-energy value. A difference is calculated between the early signal-energy value and the late signal-energy value, thereby producing an error signal.

Loading the Abstract Image...

First Claim