Abstract: An adaptive equalizer including an equalizer filter and a tap coefficients generator used to process a sample data stream derived from a plurality of received signals is disclosed. The tap coefficients generator includes an equalizer tap update unit, a vector norm square estimator, an active taps mask generator, a switch and a pilot amplitude reference unit used to minimize the dynamic range of the equalizer filter. A dynamic mask vector is used to mask active taps generated by the equalizer tap update unit when an unmasked signal output by the equalizer filter is selected by the switch to generate an error signal fed to the equalizer tap update unit. A fixed mask vector is used to mask active taps generated by the equalizer tap update unit when a masked signal output by the equalizer filter is used to generate the error signal.

Abstract: A receiver which includes at least one equalizer filter and a tap coefficients generator for implementing receive diversity. The equalizer filter processes a signal derived from signals received by a plurality of antennas. In one embodiment, sample data streams from the antennas are merged into one sample data stream. The merged sample data stream is processed by a single extended equalizer filter, whereby filter coefficients are adjusted in accordance with a joint error signal. A filter coefficient correction term used by the equalizer filter is generated by the tap coefficients generator using a normalized least mean square (NLMS) algorithm. In another embodiment, a plurality of equalizer filters are utilized, whereby each equalizer receives a sample data stream from a specific one of the antennas. In yet another embodiment, the sample data streams are combined after being processed by a plurality of matched filters based on respective estimated channel impulse responses.

Abstract: A normalized least means square (NLMS) equalizer including two equalizer filters is disclosed. In one embodiment, a single correction term generator is used to generate correction terms for tap coefficient updates of each of the equalizer filters based on a pilot signal. In another embodiment, two different correction term generators are used to generate correction terms for each of the equalizer filters, whereby one of the correction term generators uses data received from a hard decision unit at the output of one of the equalizer filters to generate correction terms for both of the equalizer filters.

Abstract: A step-size estimator for controlling the step-size of an adaptive equalizer incorporated in a transceiver, (e.g., a wireless transmit/receive unit (WTRU)). The step-size estimator updates at least one adaptive equalizer tap used by the adaptive equalizer based on an apparent speed of a channel established between the transceiver and another transceiver. The step-size estimator includes a speed estimator, a signal-to-noise ratio (SNR) averager and a step-size mapping unit. The speed estimator is used to estimate the apparent speed of the channel, (i.e., the observed and/or measured rate of change of the channel impulse response). The SNR averager generates a common pilot channel (CPICH) SNR estimate. The step-size mapping unit uses the speed estimate and the CPICH SNR estimate to generate a step-size parameter, ?, and a filter taps leakage factor parameter, ?, used by the adaptive equalizer to update the filter tap coefficient.

Abstract: A method and apparatus for estimating and correcting baseband frequency error in a receiver. In one embodiment, an equalizer performs equalization on a sample data stream and generates filter tap values based on the equalization. An estimated frequency error signal is generated based on at least one of the filter tap values. A rotating phasor is generated based on the estimated frequency error signal. The rotating phasor signal is multiplied with the sample data stream to correct the frequency of the sample data stream. In another embodiment, a channel estimator performs channel estimation and generates Rake receiver finger weights based on at least one of the finger weights. An estimated frequency error signal is generated based on at least one of the finger weights.

Abstract: A system and method for automatic gain control for a wireless transmit and receive unit in a time-slotted communications system includes initializing an automatic gain control loop, sampling a received signal, and estimating the power of the received signal. The estimated power of the received signal is compared with a reference power level and an error signal is generated based upon the difference between the estimated power and the reference power level. The error signals generated by a plurality of received signals are accumulated in an accumulator, and the value of the accumulator is looked up in a table to locate a control word for an attenuator. The control word is then passed to the attenuator to adjust the gain.