Search window delay tracking in code division multiple access communication systems

摘要

The present invention provides a search window delay tracking procedure for use in a multipath search processor of a CDMA radio receiver. A channel impulse response is estimated for a received signal containing plural paths, each path having a corresponding path delay. A search window defines a delay profile that contains the plural paths of the received signal (P1-P3). A mean or average delay (RMS Delay-Spread) is calculated for the estimated channel impulse response (CIR), and an error ( epsilon (m)) is determined between the mean CIR delay and a desired or target delay position of the Cir. search window. An adjustment is made to reduce that error to align the targeted position (T) of the search window and the mean CIR delay. A Doppler frequency is estimated for each path. The adjustment is made taking into account a Doppler effect caused by relative movement between the transmitter and receiver.