Localized QoS-Aware MAC Protocol for Real-time Dynamic Sensor Networks

Sensor networks have found important applications on real-time sensing and control. In those applications, the stringent quality of service (QoS) requirements (e.g., delay, jitter) and the dynamic nature of low-power wireless communication render existing MAC protocols undesirable. In this paper, we present RoMac, a localized QoS-aware TDMA MAC protocol for real-time dynamic sensor networks. The key contributions of RoMac include: (I) it provides collision-free communication and persistent QoS guarantee such as constant packet jitter and bounded latency; (2) it is resilient to topology dynamics and truly traffic adaptive in dynamic environments. To our best knowledge, this is the first TDMA MAC protocol that can achieve the resilience to dynamic topologies; (3) its localized design eases the need of scheduling message exchange beyond the initialization phase. We present an implementation of the protocol using the TinyOS operating system running on the iMote2 sensor mote platform. Our experiment result shows that RoMac can achieve the adaptability to dynamic changes in data collection sensor networks and provide persistent QoS support in terms of timeliness, packet jitter and fairness.