Back to results
US 4,559,625 AGranted
Interleavers for digital communications
AssigneeCyclotomics, Inc.
InventorsElwyn R. Berlekamp, Po Tong
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeCyclotomics, Inc.
InventorsElwyn R. Berlekamp, Po Tong
Estimating the term…
An improved method and apparatus for interleaving block codes exploits helical symmetry whereby correspondingly positioned code symbols of code words of length n interleaved to depth i, i<n, are separated on the channel by .alpha.i+.beta. symbol intervals where 1+.gamma..gtoreq.i is averaged over the i correspondingly positioned symbols and .alpha.and .vertline..beta..vertline. are integers >1. The requirement for synchrony is reduced to a period counted modulo n instead of mod (n.times.i). For the case i=n-1, the total interleaving delay is reduced to 2(n-1)n and phase dependence of burst error onset is minimized. The performance of the de-interleaver is enhanced through a pseudo fade detector implemented by creating erasures prior to decoding, at certain positions for codewords subsequent to confirmed error. Synchronization of interleaver and de-interleaver is accomplished in apparatus which inspects all c contiguous bit patterns corresponding to a c bit synch symbol. To each c contiguous bit pattern of the data stream there is associated a probability counter for incrementing when the synch pattern is detected and decremented otherwise. Maximum probability establishes synch.
Digital information system apparatus for communicating information comprising an ordered sequence of i digital words, each said digital word comprising an ordered sequence of n.times.i symbols, over a channel from an information source to an information destination with improved immunity from noise bursts or fading on said channel, said information source comprising encoder means for algebraically encoding information units of n symbols and to append one or more characters of redundancy thereto, comprising
An error correcting decoding system for correcting erasures and errors in an interleaved stream of digitally encoded symbols, corresponding to a plurality of codewords, said system comprising
An error correcting coding system for protecting digital information from errors, said system operating upon a data stream propagating across a communication channel, said data stream comprising digitally encoded symbols forming a plurality of codewords, comprising
The method for extending the error correcting capability of an interleaved error correcting code of length n interleaved to depth i for modulation of a communication channel, comprising the steps of
A digital communication system for error protected transmission of information in sequences of code words across a communication channel, comprising
Interleaver apparatus for resequencing digital symbols comprising first interleaver means operative upon i codewords, each said codeword comprising n symbols to produce a first sequence of n.times.i symbols and second interleaver means operative upon said first sequence to further re-sequence said n.times.i symbols to produce a second sequence, said second sequence different from said first sequence, at least one said first or second interleaver means comprising an interleaver of helical symmetry.
The method of helically interleaving blocks of digital information for serial transmission over a communication channel, each said block comprising a plurality of i independently encoded codewords, each said codeword comprising n code symbols, i less than n, said method comprising the steps of
In apparatus for resequencing code symbols for transmission across a channel, said apparatus comprising block interleaver means for interleaving i codewords, each said codeword comprising n code symbols, the improvement comprising
Dependencies are inferred from the claim text.