The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 13, 1983
Filed:
Jul. 10, 1981
Smith A Rhodes, Falls Church, VA (US);
Communications Satellite Corporation, Washington, DC (US);
Abstract
New techniques are disclosed which utilize soft detection to improve the performance of FEC codes. For an FEC code with minimum Hamming distance, the decoder utilizes hard-detected code symbols to obtain d independent estimates of each information bit, including the detected information symbol itself and d-1 orthogonal parity checks on the information bit. Soft detection is employed for the purpose of computing reliability measures for the d estimates. The reliability numbers serve as weighting coefficients, with the bit decision determined on a weighted majority basis. In one preferred technique, Reliability Majority Decoding (RMD), the reliability of each estimate is determined from some number I of the least reliable of the m hard-detected code symbols contributing to the estimate. For I=1, a simplified logic circuit can be used to determine estimate reliability, while for I=m each symbol is assigned a number of demerits inversely proportional to reliability. The demerits are totalled for each estimate and inverse mapping yields an estimate reliability. In a second preferred technique, all detected symbols are assigned equal weights for purposes of computing parity symbols, but each detected code symbol is then itself assigned a reliability which is used to determine how many parity symbol mismatches are required to overrule the bit estimate. Cascaded feedback decoding techniques can be used to further improve decoding performance. Also disclosed is a technique for providing error protection of parity symbols.