Unequal Error Protection: Some fundamental limits and optimal strategies

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 error protection is also analyzed. Even for data-rates approaching the channel capacity, we show 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 its pseudo-capacity, is fundamentally important in such problems.