Abstract: In one embodiment, a programmable vector processor performs preamble detection in a wireless communication network. Implementation of preamble detection in the vector processor is made possible by a set of vector instructions that include (i) a circular load instruction for loading vectors of received data, (ii) a correlation instruction for correlating the vectors of received data with vectors of the scrambling code to concurrently generate a plurality of complex correlations, (iii) a partial-transpose instruction for arranging vectors of the complex correlations for use by a Fast Hadamard Transform (FHT) processor, and (iv) an FHT instruction for performing FHT processing on a vector of complex correlations. Implementing preamble detection in the vector processor allows more of the received data to be processed concurrently. As a result, preamble detectors of the disclosure may detect preambles using fewer clock cycles than that of comparable preamble detectors implemented using hardware accelerators.

Abstract: A method for estimating error probability of LDPC codes includes ordering LDPC codes according to features in each code with known error characteristics. The method includes identifying features in each LDPC code having known error characteristics; adding each code to one or more categories based on the existence of such features; and ranking the LDPC codes according to the level of error risk.

Abstract: A computer-aided design method for developing, simulating, and testing a read-channel architecture to be implemented in a VLSI circuit. The method uses a coset operating mode and nonzero-syndrome-based decoding to accelerate the simulation of the read-channel's error-rate characteristics corresponding to different parity-check matrices employed in the read-channel's turbo-decoder, such as a low-density parity-check decoder. The acceleration is achieved through recycling some previously generated log-likelihood-ratio values, which enables the method to sometimes bypass certain time-consuming processing steps therein.

Abstract: In one embodiment, the present invention is a method for performing incremental preamble detection in a wireless communication network. The method processes non-overlapping chunks of incoming antenna data, where each chunk is smaller than the preamble length, to detect the signature of the transmitted preamble. For each chunk processed, chips of the chunk are correlated with possible signatures employed by the wireless network to update a set of correlation profiles, each profile comprising a plurality of profile values. Further, an intermediate detection is performed by comparing the updated profile values to an intermediate threshold that is also updated for each chunk. Upon receiving the final chunk, the correlation profiles are updated, and a final preamble detection is made by comparing the updated profile values to a final threshold. Detections are performed on an incremental basis to meet latency requirements of the wireless network.

Abstract: In one embodiment, a high-level compensation (HLC) module receives samples of an input signal and determines whether a magnitude of each sample, represented in a linear domain, is relatively low or relatively high by comparing the magnitude to a threshold. If a sample is less than or equal to the threshold, then it is considered to have a relatively low magnitude and the sample is not attenuated. If a sample is greater than the threshold, then it is considered to have a relatively high magnitude and the HLC module attenuates the sample according to a “soft” non-linear function. The “soft” non-linear function is characterized by at least two of the following characteristics: the non-linear function (i) increases monotonically, (ii) forms a convex upwards curve, (iii) has a first derivative at the threshold equal to one, and (iv) has a first derivative at a maximum possible magnitude value equal to zero.

Abstract: In one embodiment, an acoustic echo control (AEC) module receives an outgoing signal and an incoming signal, which, at various times, contains acoustic echo corresponding to the outgoing signal. The AEC module has a delay estimation block that estimates, in the time domain, the echo delay using an adaptive filtering technique. This delay estimation is used to align samples of the incoming signal having acoustic echo with the corresponding samples of the outgoing signal from which the acoustic echo originated. The AEC module determines whether or not samples of the incoming signal contain acoustic echo based on the aligned outgoing signal, and the determinations are applied to a hangover counter. The AEC module then suppresses acoustic echo in the incoming signal and adds comfort noise to the incoming signal. The amount of echo suppression performed is gradually increased or decreased based on comparisons of the counter to a hangover threshold.

Abstract: In one embodiment, a music detection (MD) module accumulates sets of one or more frames and performs FFT processing on each set to recover a set of coefficients, each corresponding to a different frequency k. For each frame, the module identifies candidate musical tones by searching for peak values in the set of coefficients. If a coefficient corresponds to a peak, then a variable TONE[k] corresponding to the coefficient is set equal to one. Otherwise, the variable is set equal to zero. For each variable TONE[k] having a value of one, a corresponding accumulator A[k] is increased. Candidate musical tones that are short in duration are filtered out by comparing each accumulator A[k] to a minimum duration threshold. A determination is made as to whether or not music is present based on a number of candidate musical tones and a sum of candidate musical tone durations using a state machine.

Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein motion-vector dispersion observed at the higher spatial resolution is quantified and used to configure the motion-vector search at the lower spatial resolution. For example, for video-frame areas characterized by relatively low motion-vector dispersion values, the motion-vector search may be performed over a relatively small vector space and with the use of fewer search patterns and/or hierarchical search levels. These constraints enable the transcoder to find appropriate motion vectors for inter-prediction coding without having to perform an exhaustive motion-vector search for these video-frame areas, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.

Abstract: A video transcoder for converting an encoded input video bit-stream having one spatial resolution into an encoded output video bit-stream having a lower spatial resolution, wherein learned statistics of intra-mode transcoding are used to constrain the search of intra modes for the output video bit-stream. The statistics of intra-mode transcoding can be gathered, e.g., by applying brute-force downsizing to a training set of video frames and then analyzing the observed intra-mode transcoding patterns to determine a transition-probability matrix for use during normal operation of the transcoder. The transition-probability matrix enables the transcoder to select appropriate intra modes for the output video bit-stream without performing a corresponding exhaustive full search, which advantageously reduces the computational complexity and processor load compared to those of a comparably performing prior-art video transcoder.