Mesh Mac Enabling Mesh Networking Over Ieee 802.15.4 Mac Layer

"Wireless sensor network is a network of sensor nodes that function in a cooperative manner to monitor the changes in the physical environment. Wireless sensor networks are used in environment and habitat monitoring, healthcare applications, building automation, and traffic control to name a few. Typically, wireless sensor node is a low power embedded device which consists of a microcontroller, sensors, wireless transceiver and a battery. These devices are usually distributed in a physical environment which makes it difficult to maintain the network manually. The IEEE 802.15.4 and Zigbee are considered as standard protocols for wireless sensor networks. The IEEE 802.15.4 standard is originally proposed for battery powered embedded devices that operate in a personal operating space. However its low power nature and the easy availability of the hardware chips based on this standard made it suitable for wireless sensor networks. Although, IEEE 802.15.4 is being considered as a promising standard for low-cost low- power Wireless Sensor Networks (WSNs), several issues in the specification are still open. One of those open issues is how to build a synchronized multi-hop mesh network for scalable, reliable and robust networking. In fact, while the current specification supports multi-hop networking using peer-to-peer topology, it restricts its usage to the beaconless mode. This thesis presents the MeshMAC, an extension to the current IEEE 802.15.4 standard in which mesh networking in the low power beacon mode is enabled through the usage of distributed beacon scheduling. The MeshMAC has been implemented on top of the Open-ZB IEEE 802.15.4 stack in TinyOS. The feasibility of the MeshMAC is demonstrated and evaluated through both physical test-bed and computer based emulation."