ON MAKING INFORMATION FEEDBACK FAIL-SAFE
Scientific rept. no. 8
NEW YORK UNIV NY COLL OF ENGINEERING
Pagination or Media Count:
Various possible decision policies are enumerated for both decision and information feedback subject to the restriction that communication be by binary sequences and that a binary decision be made for individual digits, as well as several other restrictions. It is then shown that, within the allowed class of systems, only the one decision feedback policy described previously and the two information feedback policy described herein can have the desired high-reliability fail-safe properties. The first information feedback system, which uses decision policies on the forward and feedback channels such that erasure-to-confirmation errors are always very rare on both channels, is shown to be nearly equivalent, but slightly inferior, to the decision feedback system. An exception to this statement holds when the feedback channel is extremely reliable in itself. The second information feedback system, which uses decision policies such that confirmation-to-erasure errors are always very rare on both channels, has the advantage that reliability depends on the number of information digits per code word, rather than the number of check digits as in the other systems. Thus, a saving in the number of forward channel check digits is available. The system has the disadvantage that the receiver must store tentatively a large number of words.
- Computer Hardware