Abstract: A turbo decoder iteratively decodes a received, encoded signal with one or more constituent decoders employing a simplified log-maximum a posteriori (SMAP) decoding algorithm. The SMAP decoding algorithm calculates reliability information as a log likelihood ratio for a log-MAP algorithm using a reduced set of path metrics recursively updated based on maximum likelihood recursion. Updated extrinsic information for a subsequent decoding may be derived from the LLR calculated by the SMAP decoding algorithm.

Abstract: For use in a CDMA receiver having a Viterbi decoder, a system for, and method of, performing one-pass blind transport format detection (BTFD) with respect to a received frame and a WCDMA receiver incorporating the system or the method. In one embodiment, the system includes: (1) a traceback circuit that performs a zero state BTFD traceback function with respect to at least a Viterbi-decoded portion of the frame, the traceback function being dependent upon a relative position of a BTFD checkpoint and generating hard decision bits and (2) a BTFD point selection circuit, coupled to the traceback circuit, that employs the hard decision bits to determine a location of a BTFD point with respect to the frame.

Abstract: A receiver for iterative decoding of a received, encoded signal employs slot-based scaling of soft samples. Iterative decoding employs a constituent maximum a priori (MAP) decoder for each constituent encoding of information of the encoded signal. Root mean square (RMS) values for soft samples over a slot are selected for dynamic range scaling. Squared RMS values are combined and equal the squared RMS value for a frame multiplied by a control constant, and this relationship may be employed to derive scaling constants for each slot. Alternatively, the square root of the RMS value multiplied by a constant serves as an SNR estimator that may be employed to scale samples to reduce dynamic range and modify logarithmic correction values for max* term calculation during log-MAP decoding.

Abstract: A receiver for iterative decoding of a received, encoded signal employs slot-based scaling of soft samples. Iterative decoding employs a constituent maximum a priori (MAP) decoder for each constituent encoding of information of the encoded signal. Root mean square (RMS) values for soft samples over a slot are selected for dynamic range scaling. Squared RMS values are combined and equal the squared RMS value for a frame multiplied by a control constant, and this relationship may be employed to derive scaling constants for each slot. Alternatively, the square root of the RMS value multiplied by a constant serves as an SNR estimator that may be employed to scale samples to reduce dynamic range and modify logarithmic correction values for max* term calculation during log-MAP decoding.

Abstract: A turbo decoder iteratively decodes a received, encoded signal with one or more constituent decoders employing a simplified log-maximum a posteriori (SMAP) decoding algorithm. The SMAP decoding algorithm calculates reliability information as a log likelihood ratio for a log-MAP algorithm using a reduced set of path metrics recursively updated based on maximum likelihood recursion. Updated extrinsic information for a subsequent decoding may be derived from the LLR calculated by the SMAP decoding algorithm.

Abstract: A turbo decoder employs max* term or max term maximum a priori (MAP) decoding of received, encoded data. Initially, MAP decoding is iterative and employs max* term computation of log-likelihood values at each iteration. Max* term computation includes computation of a max term and a logarithmic correction term. A bypass algorithm switches from max* term computation to only max term computation in later iterations with little or no degradation in decoder performance. The iteration selected for switching may be based on increasing intrinsic signal-to-noise ratio (SNR) of the iterative MAP decoding. Since, in general, fewer computations are required for max term computation than for max* term computation, switching between max* and max allows for reduced power consumption of a particular decoder implementation.

Abstract: A turbo decoder iteratively decodes a received, encoded signal with one or more constituent decoders employing a simplified log-maximum a posteriori (SMAP) decoding algorithm. The SMAP decoding algorithm calculates reliability information as a log likelihood ratio for a log-MAP algorithm using a reduced set of path metrics recursively updated based on maximum likelihood recursion. Updated extrinsic information for a subsequent decoding may be derived from the LLR calculated by the SMAP decoding algorithm.

Abstract: A turbo decoder iteratively decodes a received, encoded signal with one or more constituent decoders employing a simplified log-maximum a posteriori (SMAP) decoding algorithm. The SMAP decoding algorithm calculates reliability information as a log likelihood ratio for a log-MAP algorithm using a reduced set of path metrics recursively updated based on maximum likelihood recursion. Updated extrinsic information for a subsequent decoding may be derived from the LLR calculated by the SMAP decoding algorithm.

Abstract: A turbo decoder iteratively decodes a received, encoded signal with one or more constituent decoders employing a simplified log-maximum a posteriori (SMAP) decoding algorithm. The SMAP decoding algorithm calculates reliability information as a log likelihood ratio for a log-MAP algorithm using a reduced set of path metrics recursively updated based on maximum likelihood recursion. Updated extrinsic information for a subsequent decoding may be derived from the LLR calculated by the SMAP decoding algorithm.

Abstract: For use in a CDMA receiver having a Viterbi decoder, a system for, and method of, performing one-pass blind transport format detection (BTFD) with respect to a received frame and a WCDMA receiver incorporating the system or the method. In one embodiment, the system includes: (1) a traceback circuit that performs a zero state BTFD traceback function with respect to at least a Viterbi-decoded portion of the frame, the traceback function being dependent upon a relative position of a BTFD checkpoint and generating hard decision bits and (2) a BTFD point selection circuit, coupled to the traceback circuit, that employs the hard decision bits to determine a location of a BTFD point with respect to the frame.

Abstract: A receiver for iterative decoding of a received, encoded signal employs slot-based scaling of soft samples. Iterative decoding employs a constituent maximum a priori (MAP) decoder for each constituent encoding of information of the encoded signal. Root mean square (RMS) values for soft samples over a slot are selected for dynamic range scaling. Squared RMS values are combined and equal the squared RMS value for a frame multiplied by a control constant, and this relationship may be employed to derive scaling constants for each slot. Alternatively, the square root of the RMS value multiplied by a constant serves as an SNR estimator that may be employed to scale samples to reduce dynamic range and modify logarithmic correction values for max* term calculation during log-MAP decoding.

Abstract: A turbo decoder employs max* term or max term maximum a priori (MAP) decoding of received, encoded data. Initially, MAP decoding is iterative and employs max* term computation of log-likelihood values at each iteration. Max* term computation includes computation of a max term and a logarithmic correction term. A bypass algorithm switches from max* term computation to only max term computation in later iterations with little or no degradation in decoder performance. The iteration selected for switching may be based on increasing intrinsic signal-to-noise ratio (SNR) of the iterative MAP decoding. Since, in general, fewer computations are required for max term computation than for max* term computation, switching between max* and max allows for reduced power consumption of a particular decoder implementation.