Behavior of IEEE 802.11 devices under interference

Abstract

IEEE 802.11 suite of protocols is the de facto standard for wireless local area networks, extending to a wide breadth of application domains. One such domain is robotics and teams of cooperating mobile agents. This is a challenging domain due to ad-hoc links and highly dynamic topology. Improving the use of the Radio-Frequency channel requires some level of coordination of transmissions in time and space. However, achieving this level of coordination requires that the network interface cards (NICs) behave in a predictable manner, at least following the Medium Access Control (MAC) protocol. In this preliminary work we report early intriguing observations with existing NICs that are lenient to interpretations of the standard MAC resulting in different ways to handle interference in the medium. Some NICs do not seem to respect an interference zone as commonly defined and silently impose very different buffering/delay trade-offs, with consequences for overlay protocols, particularly TDMA.