| Wireless ad hoc networking is one of the most promising technologies. The recent decade has seen a significant advance in the area of wireless ad hoc networks. In such networks, the available resources such as battery, computational power, and communication bandwidth are scarce. This dissertation aims on the resource efficiency in wireless ad hoc networks by studying topology control, routing and virtual backbone schemes which minimize battery usage, computation and communication overhead. We classify the wireless ad hoc networks into two categories: static networks and mobile networks.; For static networks such as wireless sensor networks where sensors are deployed on non-moving objects, conservation of battery energy is one of the most important objectives. This is directly related to the network lifetime since once a critical node, such as vertex cut in the network, has depleted its battery energy, the network is partitioned. This dissertation presents two approaches to achieve increased energy efficiency in static networks. Sensors can be partitioned into disjoint dominating sets so that sensors in each group perform sensing and communication tasks in turn. In addition to the total energy consumption, balancing of energy consumption plays an important role in increasing the network lifetime. Using the fact that minimum spanning tree has the minimum longest edge among all spanning trees, a broadcast and multicast tree which balances the energy consumption can be constructed. In order to reduce the communicational bandwidth by limiting redundant retransmission, virtual backbones are studied so that only the nodes in the backbone can retransmit the received message. Using a Steiner tree approximation, this dissertation proposes the construction of a virtual backbone with improved performance ratio.; In mobile networks where computing devices move around, the nodal mobility can disturb the network topology. Under such conditions, the routing protocols that do not take nodal mobility into account may be inefficient by repeatedly updating the route information. This dissertation presents a new reliable virtual backbone scheme which takes into account the nodal mobility and uses only local information. The proposed scheme significantly increases the backbone lifetime and it is efficient in both construction and maintenance. |
