US 6,983,125 B2
Method and apparatus for varying the length of an adaptive equalizer based on doppler frequency
John E. Smee, San Diego, Calif. (US); Ivan Jesus Fernandez-Corbaton, San Diego, Calif. (US); and Srikant Jayaraman, San Diego, Calif. (US)
Assigned to Qualcomm Incorporated, San Diego, Calif. (US)
Filed on Sep. 25, 2001, as Appl. No. 9/965,204.
Prior Publication US 2003/0078025 A1, Apr. 24, 2003
Int. Cl. H04B 1/00 (2006.01); H03H 7/30 (2006.01)
U.S. Cl. 455—63.1 28 Claims
OG exemplary drawing
 
1. In a wireless communications system wherein an equalizer is used to reduce interference on a communications channel, wherein a Doppler frequency is reflective of a rate of change of the communications channel, and wherein the equalizer comprises a main tap, a first number of causal taps, and a second number of anti-causal taps, a method for adjusting a length of the equalizer comprising increasing the length as the Doppler frequency decreases, and decreasing the length as the Doppler frequency increases, wherein said increasing comprises determining whether said causal taps are more useful than said anti-causal taps, and if so, increasing said first numbers, and if not, increasing said second number.