some fundamental limits of unequal error protection

Various formulations are considered where some information is more important than other and needs better protection. Our information theoretic framework in terms of exponential error bounds provides some fundamental limits and optimal strategies for such problems of unequal error protection. Even for data-rates approaching the channel capacity, it shows how a crucial part of information can be protected with exponential reliability. Channels without feedback are analyzed first, which is useful later in analyzing channels with feedback. A new channel parameter, called the Red-Alert Exponent, is fundamentally important in such problems.