Error exponents in asynchronous communication

Based on recent work on asynchronous communication, this paper proposes a slotted asynchronous channel model and investigates the fundamental limits of asynchronous communication, in terms of miss and false alarm error exponents. We propose coding schemes that are suitable for various asynchronous communication scenarios, and quantify more precisely the suboptimality of training-based schemes, i.e., communication strategies that separate synchronization from information transmission. In particular, we show that under a broad set of conditions, training-based schemes are suboptimal at all positive rates. Finally, we demonstrate these performance differences by specializing our results to BSCs and AWGN channels.