Lucent Technologies Inc.

Mark David Hahm

R Michael Buehrer

Shang-Chieh Liu

Steven P Nicoloso

Stephan A Allpress

A recursive, single-wrong-turn (SWT) decoding method and Viterbi decoder which requires no additional circuitry or processing to keep track of a running list of the L best paths. If the most likely (ML) path fails frame quality metric tests, a search is made through a trellis using an existing survivor (trace back) information stored in a survivor (trace back) memory. An iteration in the recursive algorithm includes tracing back along the ML path to a particular stage, then deviating from the ML path and following the survivor information along that new deviant path, and finally checking the fully decoded frame to see if the frame quality metrics are acceptable for the frame. These same trace back steps can be performed for every stage in the trellis, deviating from a different stage on the ML path each time. A recursive, single-wrong-turn (SWT) decoding method and Viterbi decoder which exceed the performance of the general Viterbi algorithm and the various conventional list Viterbi decoders and which is much less computationally and physical complex.

Viterbi decoding using single-wrong-turn correction

A method and device for limiting peaks of an input signal. The device and method isolate peaks of an input signal based on a clipping threshold voltage, generate an extrema signal representing the local extrema of the peak isolated signal, filter the extrema signal based on an appropriate impulse filter response to generate a filter signal, and combine the filter signal with the input signal delayed by a predetermined time period to generate an impulse clipped signal. The impulse clipped signal has a reduced P/A ratio and is without significant out-of-band spectrum artifacts.

Device and method for limiting peaks of a signal

A Fast Hadamard Transform apparatus having a plurality of transform stages, such as would be employed by a wireless telecommunication system for detecting and correcting errors that occur during the transmission of coded signal blocks, such as a Walsh codeword. Each stage of the apparatus comprises an adder and a subtractor, each having an output terminal. The adder and the subtractor are configured to receive signal pairs and generate intermediate coefficients. A first memory unit is coupled to the output terminal of the adder and to the output terminal of the subtractor, and is configured to receive a first specifiable sequence of the intermediate coefficients from the adder and a second specifiable sequence of the intermediate coefficients from the subtractor. A second memory unit is coupled to the output terminal of the subtractor so as to receive a third specifiable sequence of the intermediate coefficients from the subtractor. The first memory unit and the adder provide concurrently a plurality of intermediate coefficient signal pairs to a subsequent transform stage, and the first and second memory units provide concurrently a plurality of other intermediate coefficient signal pairs to the subsequent transform stage.

Hardware efficient fast hadamard transform engine

The base station system includes a cancellation processor connected to a plurality of conventional signal processors. Under the control of a controller, the signal processors acquire user signals in signals received by the base station antennas. The controller controls the cancellation processor to perform cancellation operations with respect to the acquired user signals. The cancellation processor includes first-nth filter stages. Each filter stage operates in the same manner. A filter stage obtains, in parallel, the acquired user signals from signals supplied thereto by estimating symbols in the acquired user signals under the control of the controller. The cancellation processor also includes a cancellation stage associated with each filter stage. Each cancellation stage cancels, in parallel, the obtained user signals output from the associated filter stage from the signals received by the base station antennas. The resulting residual signals output from a cancellation stage are supplied to the next filter stage, and the signals supplied to the first filter stage are the signals received by the base station antennas. A cancellation stage cancels the obtained user signals received thereby from the received signals at a substantially same time with respect to the received signals.

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Flanders, NJ, United States of America

Mark David Hahm