M.Sc Thesis
M.Sc Student Zeitlin Oren Error Exponents of Fixed Block Binary Messaging through DMCS Department of Electrical Engineering Professor Neri Merhav

Abstract

We consider error exponents for binary messaging through discrete memoryless channels, in various scenarios involving the presence of states, feedback, channel uncertainty, causality and delay constraints.

One scenario considered in detail is channels with states known both at the encoder and the decoder. We characterize the error exponents both for the case of causal and non-causal availability of states at the encoder, showing that the latter can be strictly better than the former. We show that feedback does not improve the reliability in these cases, nor does positive state look ahead improve on the reliability of the channel with causal states knowledge.

We also consider the case of unknown channel parameters and show that, in general, channel uncertainty results in lower exponents. We characterize the exponent in the case of a BSC whose crossover probability is known to be either p or 1-p, with and without noise-free feedback. We also derive a lower bound on the exponent for the case of noisy BSC-corrupted feedback and show that reliability is boosted relative to the absence of feedback when the crossover probability in the feedback channel is low enough.