SDMAC: A Software-Defined MAC for Wi-Fi to Ease Implementation of Soft Real-Time Applications

In distributed control systems where devices are connected through Wi-Fi, direct access to low-level medium access control (MAC) operations may help applications to meet their timing constraints. In particular, the ability to timely control single transmission attempts on air, by means of software programs running at the user space level, eases the implementation of mechanisms aimed at improving communication timeliness and reliability. Relevant examples are deterministic traffic scheduling, seamless channel redundancy, rate adaptation algorithms, and so on. In this paper, a novel architecture is defined, we call software-defined MAC (SDMAC), which in its current embodiment relies on conventional Linux PCs equipped with commercial Wi-Fi adapters. Preliminary SDMAC implementation on a real testbed and its experimental evaluation showed that integrating this paradigm in the existing protocol stacks constitutes a viable option, whose performance suits a wide range of applications characterized by soft real-time requirements.