Wireless Communication Using Real-Time Extensions to the Linux Network Subsystem

Abstract

Timely wireless communication is essential to allow real-time mobile applications, e.g., communication between mobile robots and intervehicle communication to be realized. The current IEEE 802.11 ad hoc protocol is unable to provide real-time communication guarantees due to its underlying contention-based MAC layer. Our current research is addressing the implementation of a time-bounded MAC protocol as a layer above 802.11. The implementation of a timely MAC protocol requires predictable and deterministic behavior at the device driver level, currently unavailable in the Linux operating system. This paper describes real-time extensions to the Linux operating system to provide real-time guarantees at the device driver level. To our knowledge, we are the first to implement a real-time ORiNOCO driver for real-time Linux. In addition we provide a low-level evaluation of the timeliness of packet transmission achievable using IEEE 802.11.