In this paper, we introduce existing asynchronous duty cycling MAC protocols for WSNs. We first outline important issues for the design of MAC layer protocols. We categorize existing duty cycling MAC protocols proposed for WSNs into the preamble sampling MAC protocol and the beacon frame MAC protocol. We introduce them describing their advantages and disadvantages. Finally, we present an analysis table that compares performance of each MAC protocol based on the design issue we define.

WSNs, MAC, preamble sampling, beacon frame, asynchronous, duty cycling.