Real-Time Traffic in Ad-hoc Sensor Networks

The usage of sensors is emerging in the nowadays scenario where safety related applications are more and more used. These applications have timing constraints that need to be met by the control system. Thus, guaranteeing timeliness properties is considered a key challenge for research on wireless sensor networks. Among the different components that need to address this problem, we focus on the communication subsystem and, in particular, on the MAC protocols that handles transmissions. To provide timeliness behavior, the employed MAC protocol has to provide a time-bounded service. The contribution of this paper is to investigate the performance of two wireless MAC protocols that can be employed in wireless sensor networks: IEEE 802.11e and WRT-Ring. The former is part of the well know IEEE 802.11 standard, whereas the latter has characteristics that well fit the requirements of wireless sensor networks. Results show that two protocols have similar performances for networks with limited devices and/or traffic, whereas when devices and/or traffic increases, WRT-Ring has to be preferred.