Error Exponents of Asynchronous and Controlled Asynchronous Multiple Access Channels

Lóránt Farkas

Budapest University of Technology and Economics (BUTE), Hungary

Abstract:

Csiszar-style exponential error bounds are derived for frame-asynchronous discrete memoryless multiple access channels with two senders. To achieve this, the method of types is generalized to asynchronous setting leading to the new concept of subtypes. An intermediate formula is given, that very resembles to the formulas given in synchronous systems by Liu and Hughes, though it is uncomputable. The formula can be simplified to a computable one, by delta-balancig the codewords. By evaluation for a particular case, it follows that the best error exponent known for synchronous transmission may be beaten if the senders are allowed to use controlled asynchronism, where transmission happens with a chosen delay. The controlled asynchronism can be used also in place of rate splitting in successive cancellation detection.

Biography:

Lóránt Farkas was born in Budapest, Hungary, in 1979. He received M.Sc. degree in mathematics at the Budapest University of Technology and Economics (BUTE), Hungary, in 2002. He is currently pursuing the Ph.D. degree in mathematics at BUTE. From 2002 he was at BUTE and Hungarian Academy of Science in various research jobs. Since 2008 he has been an assistant lecturer at the Department of Analysis, BUTE. His research interest includes extending the method of types and typical sequences to various areas such as quantum information theory, gaussian channels with ISI or asynchronous multiple access channels.