A wireless MAC method with support for heterogeneous data traffic

An important aspect of any communication technology is its medium access method, being responsible for sharing the medium among users. For delay-sensitive applications, such as industrial control systems, timely and reliable channel access is of essence. Hence, existing protocols like HART and TTEthernet use a time-triggered medium access approach. However, as the nature of industrial control systems change and evolve, there is a growing need to provide wireless access and support data traffic with mixed requirements. While technologies like WirelessHART can offer timely and reliable access to the wireless medium, only one type of data traffic is usually supported. In this paper, we therefore propose and evaluate three different medium access methods for wireless communications, all capable of supporting three different data traffic classes: time-triggered, rate-constrained and best-effort traffic. In particular, different options on how to handle best-effort traffic, using scheduled time-slots or contention, are evaluated, showing for all the proposals different drawbacks and benefits depending on additional requirements on e.g., hardware, protocol overhead and resistance to interference.