Optimal Sequential Frame Synchronization

We consider the ‘one-shot frame synchronization problem’ where a decoder wants to locate a sync pattern at the output of a channel on the basis of sequential observations. We assume that the sync pattern of length N starts being emitted at a random time within some interval of size A, that characterizes the asynchronism level between the transmitter and the receiver. We show that a sequential decoder can optimally locate the sync pattern, i.e., exactly, without delay, and with probability approaching one as N → ∞, if and only if the asynchronism level grows as O(eNα ), with α below the synchronization threshold, a constant that admits a simple expression depending on the channel. This constant is the same as the one that characterizes the limit for reliable asynchronous communication, as was recently reported by the authors. If α exceeds the synchronization threshold, any decoder, sequential or non-sequential, locates the sync pattern with an error that tends to one as N â†...

• Type: Journal
• Year: 2007
• Where: CORR
• Authors: Venkat Chandar, Aslan Tchamkerten, Gregory W. Wornell
• Keywords: Asynchronism Level, CORR 2007, Decoder, Education, Sync Pattern