Binary causal-adversary channels

Michael Langberg, S. Jaggi, B. K. Dey

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


In this work we consider the communication of information in the presence of a causal adversarial jammer. In the setting under study, a sender wishes to communicate a message to a receiver by transmitting a codeword x = (x1, ⋯ , xn) bit-by-bit over a communication channel. The adversarial jammer can view the transmitted bits xi one at a time, and can change up to a p-fraction of them. However, the decisions of the jammer must be made in an online or causal manner. Namely, for each bit xi the jammer's decision on whether to corrupt it or not (and on how to change it) must depend only on xj for j ≥ i. This is in contrast to the "classical" adversarial jammer which may base its decisions on its complete knowledge of x. We present a non-trivial upper bound on the amount of information that can be communicated. We show that the achievable rate can be asymptotically no greater than min{1 - H(p), (1 - 4p)+}. Here H(.) is the binary entropy function, and (1 - 4p) + equals 1 - 4p for p ≥ 0.25, and 0 otherwise.

Original languageEnglish
Title of host publication2009 IEEE International Symposium on Information Theory, ISIT 2009
Number of pages5
StatePublished - 2009
Event2009 IEEE International Symposium on Information Theory, ISIT 2009 - Seoul, Korea, Republic of
Duration: 28 Jun 20093 Jul 2009

Publication series

NameIEEE International Symposium on Information Theory - Proceedings
ISSN (Print)2157-8102


Conference2009 IEEE International Symposium on Information Theory, ISIT 2009
Country/TerritoryKorea, Republic of


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