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Patent Abstracts
Patent titles, numbers and abstracts are given below. For complete versions, please visit either the U.S Patent and Trademark Office or the Canadian Intellectual Property Office.
Forward Error Correction (FEC)
[CRO00a_Patent] S. Crozier, A. Hunt, J. Lodge, "High-performance low-complexity error-correcting codes"
U.S. Patent 6,145,111
November 7, 2000
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A method of encoding data is described herein. According to the method, source data elements are coded using one or more product codes having a common component code. The resulting one or more primary product codewords consist of a plurality of first codewords of the common component code. One or more first sets of codewords of the common component code are assembled such that each of the first sets comprises two or more distinct first codewords forming part of a same primary product codeword. Each of the codewords of each of the first sets is codeword-mapped to a second codeword of the common component code using a one-to-one codeword-mapping. One or more second sets of second codewords are provided, where each second set corresponds to a first set of codewords. The codeword-mapping includes re-ordering, according to a known interleaving pattern, the symbols within a codeword. The codeword-mappings are such that if all of the codewords of a first set are from a same primary product codeword, then some codeword-mappings applied to the codewords of the first set are different, and if two or more repetitions of a same codeword are included in a single first set, then the codeword-mappings applied to those repetitions are different. Each set of second codewords is coded using a systematic code so as to generate a secondary product codeword for a product code having as component codes the common component code and the systematic code. Then, the primary product codewords and the non-systematic portion of the secondary product codewords are provided as encoded output data.
[CRO00b_Patent] S. Crozier, A. Hunt, J. Lodge, "Method of enhanced max-log-a posteriori probability processing"
U.S. Patent 6,145,114
November 7, 2000
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The invention comprises an enhancement to max-log-APP processing that significantly reduces performance degradation associated with introducing the "max" approximation into log-APP computations, while still maintaining lower computational complexity associated with max-log-APP processing. This enhancement is achieved by adjusting extrinsic information produced by a max-log-APP process where the magnitude of the extrinsic information is reduced, for example, by multiplying it with a scale factor between 0 and 1.
[CRO05_Patent] S. Crozier, P. Guinand, "High-performance low-memory interleaver banks for turbo-codes"
U.S. Patent 6,857,087
February 15, 2005
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An interleaver for interleaving a set of K ordered elements is disclosed herein. The disclosed interleaver can be expressed as a single permutation that corresponds to two local dithering operations and a global permutation operation. The single permutation can be represented as a small collection of short vectors, and can be calculated recursively, allowing the interleaver to be both stored and implemented using a smaller amount of memory than conventionally possible.
[HUN05_Patent] A. Hunt, "Code structure, encoder, encoding method, and associated decoder and decoding method and iteratively decodable code structure, encoder, encoding method, and associated iterative decoder and iterative decoding method"
U.S. Patent 6,944,803
September 13, 2005
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A class of codes and associated methods and devices are provided. Advantageously, such codes when used as constituent codes in composite codes intended for iterative decoding, as compared to the standard practice of using convolutional codes, may allow better error-correcting performance to be achieved, especially at low error rates and high code rates, for a given decoder complexity. State sequencing in these codes is driven not by source data alone, as is the case with convolutional codes, but rather by a sequence that includes both the source data and so-called "inserted" data elements, the inserted data elements having a linear dependence on the state sequencing state. In decoding, state transition intervals involving one or more inserted data elements are handled in a special way.
[MOH00_Patent] M. Moher, "Joint detector for multiple coded digital signals"
U.S. Patent 6,161,209
December 12, 2000
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A method for the joint detection of multiple coded digital signals that share the same transmission medium in a manner that causes mutual interference. The method is comprised of two steps that are applied to preliminary estimates of each digital signal, one or more times. The first step is to obtain reliability estimates for each data element of each digital signal by combining the preliminary estimates, a statistical model for the interference, and any a priori information regarding the data elements. The second step is to revise these reliability estimates for each digital signal based on the forward error correction code used for that digital signal. When the steps are repeated, the revised reliability estimates from the second step are used as a priori information for the first step.
[MOH04_Patent] M. Moher, S. Crozier, P. Guinand, "Method and system for detection of short digital radio messages"
U.S. Patent 6,693,983
February 17, 2004
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Digital signals transmitted on an RF carrier modulated in phase and amplitude and subject to noise constitute separate bursts each comprising information symbols of data and a pair of separated unique words. The signals are subjected to processing which involves reception of the signals and an initial conversion to approximate baseband and then analog to digital sampling. Quadrature and in phase samples are then stored in a buffer. The buffered samples are subjected to coarse timing, coarse frequency synchronization, a first phase correction, fine timing, further phase and amplitude correction and finally to fine frequency correction and subsequent reliability estimation.
