Energy-efficient, Reliable, and Flexible Data Transmission in Wireless Personal Area Networks

Wireless personal area network (WPAN) is a standard for wireless communication with short range such as a space around a person. Because of the demand for low power, low cost wireless communication, a low-rate WPAN (LR-WPAN) comes out. Wireless sensor network (WSN) recognizes a wireless technology to support the LR-WPAN services. The WSN consists of a large number of tiny sensor nodes. It constructs ad-hoc network and monitors physical phenomena. Thus it is considered a base technology to implement a ubiquitous computing environment. Since the tiny sensor nodes have limited resources, routing algorithms for WSN should be energy-efficient. Cluster-based hierarchical routing algorithms are known to be more efficient than flat routing algorithms because only cluster-heads communicate with a sink node. Existing hierarchical routing algorithms, however, assume unrealistically large radio transmission ranges of sensor nodes so they cannot be employed in a real environment. Therefore, considering practical transmission range of the sensor nodes, this thesis proposes a clustering and routing method for hierarchical sensor networks: The proposed clustering algorithm provides the optimal ratio of cluster-heads and a clustering scheme which expands the range of clusters until d-hop calculated by the ratio of cluster-head. The proposed routing method provides an intra-cluster routing to transmit data from source nodes to their cluster-head and an inter-cluster routing to deliver data from cluster-heads to a sink node. The efficiency of the proposed clustering and routing method is validated through extensive simulations. In WSN, due to high packet loss rate during multi-hop transmissions, reliable end-