Telefonaktiebolaget Lm Ericsson (publ)

Christer &Ouml;stberg

Roozbeh Atarius

H&aring;kan Eriksson

Bengt Lindoff

Yi-Pin Eric Wang

Torgny Palenius

Torsten John Carlsson

Kjell Berthold Gustafsson

Fredrik Jaenecke

H&aring;kan Henningsson

Channel estimation is performed in a mobile communications system. In order to reduce the computational load, and thereby decrease power consumption, a polynomial expression is used to approximate a Minimum Mean Squared Error (MMSE) based channel estimator with respect to Doppler and SIR variations. A lookup table may be used to supply coefficients for the polynomial expression. In another aspect of the invention, coefficients for the polynomial expression may, themselves, be approximated by a second polynomial expression.

Approximated MMSE-based channel estimator in a mobile communication system

A receiver can identify the source of a signal from an unsynchronized source. The receiver has an antenna for receiving two signals. The receiver correlates the first signal with a code to find a first location in time, and correlates the second signal with the same code to find a second location in time. The receiver calculates a time difference between the first location in time and the second location in time and uses the time difference to identify the source of the two signals. A group of base stations or directional antennas use the same long code and synchronization codes. However, each source shifts the long code by a different amount so that for any two sources there is a unique difference between the shifts in the long code. Each source shifts a set of synchronization codes the same amount as the long code. The synchronization codes can be any short code that is relatively easy for the mobile station to detect. When the receiver receives the two signals, the receiver calculates the difference in the shifts. Because there is a unique difference for each pair of sources, the receiver can identify the source of a signal from an unsynchronized source without having to connect to the source to use a broadcast channel or control channel. The receiver can distinguish between different synchronized sources without any prior synchronization.

Method and apparatus for identifying the source of a digital signal

A method, apparatus, and system perform fast sector identification and base station synchronization. The base station transmits information in primary and secondary control channels to the remote station. The remote station performs synchronization using information in the primary and secondary control channels. A group of identification codes corresponding to the sector is determined using information in the secondary control channel. If this does not result in identification of the sector, an identification code corresponding to the sector is determined from information in the primary control channel. If this does not result in identification of the sector, the sector is identified based on information multiplied with symbols, e.g., pilot symbols, in the primary control channel, without having to decode the BCCH.

Method, apparatus, and system for fast base synchronization and sector identification

The present invention provides a system and method for reducing the power consumed by a RAKE receiver. In exemplary embodiments of the present invention, an environment variation estimator is implemented in a CDMA mobile station. The environment variation estimator is connected to the searcher of the RAKE receiver and provides an estimate of the rate at which the mobile station's environment is changing. By providing an estimate of the rate of change of the mobile station's environment, the duty cycle of the searcher can be optimized, thereby reducing the overall power consumed by the receiver. By also providing the estimate to the RAKE fingers, channel tracking can be improved.

Growing community of inventors

Staffanstorp, Sweden

Christer Östberg

Growing community of inventors

Staffanstorp, Sweden

Christer &Ouml;stberg

Christer Östberg