| Abstract: |
Advancements in technologies in the recent ten years brought to us the promising technology of wireless sensor networks (WSNs). WSNs are networks that consist of a large number of nodes that communicate using a wireless mediwn. These nodes are small devices with limited capabilities. Batteries are used to provide the nodes with therequired power to operate their circuits. Replacement of batteries is impossible, in most cases, as the network is deployed in a large scale, usually in a harsh environment.Therefore, techniques that prolong the nodes’ lifetime are required. from network wide perspective, a single node failure may bring the entire network down, so methods that extend the lifetime of the network are demanded.The lifetime problem was addressed in many ways. The concept was to alter theWSN at each layer and provide means to reduce energy consumption, hence increase the lifetime of the nodes as well as the network. An important layer to think about when studying the energy consumption is the network layer. In this layer, nodes build paths tofollow when delivering data to the BS. It is involved every time a data communication process is needed. Communication is more power demanding than computation, so efficient network layer protocols - that can reduce the amount of communicated packetsto the BS and make efficient selection and usage of communication paths - are desired.The power used to transmit a packet is proportional to the distance from the source to the destination. For that, a technique to shorten the transmission distance should be developed.Multi-hop transmission is the process of forwarding data to a neighbor node using short-range transmission, instead of directly sending the data to the BS with long-range transmission. This makes it necessary to have several transmission-power-levels in thenodes’ transceivers. These levels can be changed according to the needed transmission distance. Relying on multi-hop transmission, as a method for lessening transmission distance, can reduce energy consumption.Clustering is a technique in which nodes in the network are grouped together in a number of clusters. Each cluster is composed of a cluster head (CH) and clustermembers (CMs), where CMs do not communicate directly to the base station. Instead, CMs send their data, using short-range transmission, to the CH, which, in turn, sends
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