Search window delay tracking in code division multiple access communication systems

US6370397B1 · kind B1 · utility

Assignee

• Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventors

• Branislav M. Popović · Solna, SE
• Frank-Mike Georg · Dillenburg, DE
• Matthlas Schulist · Erlangen, DE
• Göran N. Klang · Solna, SE

Key dates

• Filing date: May 1, 1998
• Grant date: Apr 9, 2002
• Expiry date: May 1, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B1/7117
• WIPO field: Telecommunications
• WIPO sector: Electrical engineering

Abstract

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 responses 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. A mean or average delay is calculated for the estimated channel impulse response (CIR), and an error is determined between the mean CIR delay and a desired delay position corresponding to the center of the CIR search window. An adjustment is made to reduce that error so that the center of the search window and the mean CIR delay are aligned. The error may be processed either linearly (in one embodiment) or non-linearly (in another embodiment) to minimize the error and to reduce an influence of noise. A non-linear filtering process includes calculating a delay spread from the mean CIR delay calculated for successive processing cycles of a window delay tracking procedure corresponding to each new input. A difference is determined between the successive delay spreads. Adjustment signal is set equal to the error signal if the …