Providing Hard Real-Time Guarantees in Context-Aware Applications: Challenges and Requirements

Context-aware applications rely on the ability to perceive the state of the surrounding environment. In this paper, we address a class of such applications where real-time guarantees are required on top of mobile ad hoc networks. While guaranteed timeliness is a critical requirement, the unpredictability of dynamic wireless networks adversely impacts such guarantees. Therefore, we identify the challenges and the requirements on different architectural levels in order to provide timeliness guarantees. None of the existing systems have succeeded in providing adequate solutions to all of the identified requirements. Therefore, we describe a cross-layer architecture that supports the development of real-time context-aware applications for wireless networks, in particular, ad hoc networks. This cross-layer architecture is based on three main components. (i) Sentient objects - mobile intelligent software agents that extract, interpret and use context information. (ii) Event-based real-time middleware supports communication between sentient objects and provides hard real-time guarantees within adaptable geographic spaces. (iii) A real-time routing and resource reservation protocol attempts to discover and maintain real-time constrained routes within these proximities in a multi-hop ad hoc network