—An information-theoretic framework for unequal error protection is developed in terms of the exponential error bounds. The fundamental difference between the bit-wise and message-wise unequal error protection (UEP) is demonstrated, for fixed-length block codes on discrete memoryless channels (DMCs) without feedback. Effect of feedback is investigated via… (More)
—A lower bound bound is established on the error probability of fixed-length block-coding systems with finite memory feedback, which can be described in terms of a time dependent finite state machine. It is shown that the reliability function of such coding systems over discrete memoryless channels is upper-bounded by the sphere-packing exponent.
Schalkwijk and Kailath (1966) developed a class of block codes for Gaussian channels with ideal feedback for which the probability of decoding error decays doubly exponentially in block length for rates below capacity. This well-known but surprising result is explained and simply derived here in terms of a result by Elias (1956) concerning the minimum… (More)
—In a remarkable paper published in 1976, Burna-shev determined the reliability function of variable-length block codes over discrete memoryless channels (DMCs) with feedback. Subsequently, an alternative achievability proof was obtained by Yamamoto and Itoh via a particularly simple and instructive scheme. Their idea is to alternate between a communication… (More)
— Variable-length block-coding schemes are investigated for discrete memoryless channels (DMC) with perfect feedback under cost constraints. Upper and lower bounds are found for the minimum achievable probability of decoding error Pe,min as a function of transmission rate R, cost constraint P, and expected block length τ. For given P and R, the lower and… (More)
As modern infrastructure systems become increasingly more complex, we are faced with many new challenges in the area of information security. In this thesis we examine some approaches to security based on ideas from information theory. The protocols considered in this thesis, build upon the " wiretap channel, " a model for physical layer security proposed… (More)
— Fixed length block codes on discrete memoryless channels with feedback are considered for errors and erasures decoding. Upper and lower bounds are derived for the error exponent in terms of the rate and the erasure exponents. In addition the converse result of Burnashev for variable length block codes is extended to include list decoding.
A new technique is proposed for upper bounding the error probability of fixed length block codes with feedback. Error analysis is inspired by Gallager's error analysis for block codes without feedback. Zigangirov-D'yachkov (2-D) encoding scheme is analyzed with the technique on binary input channels and k-ary symmetric channels. A strict improvement is… (More)
The bit-wise unequal error protection problem, for the case when the number of groups of bits ℓ is fixed, is considered for variable length block codes with feedback. An encoding scheme based on fixed length block codes with erasures is used to establish inner bounds to the achievable performance for finite expected decoding time. A new technique for… (More)
— 1 Various scenarios are considered where some information is more important than other and needs better protection. A general theoretical framework for unequal error protection is developed in terms of exponential error bounds. It provides some fundamental limits and optimal strategies for such problems. A new class of problems called message-wise unequal… (More)