Dr. Maurits de Graaf
5th March 2009
In a wireless sensor network, a communications session is achieved either through single-hop transmission, if the recipient is within the transmission range of the source, or by relaying through intermediate nodes. In the talk we will provide an overview of various problems that exist when the aim is to create reliable networks with a long network lifetime. (Network lifetime: the time until the first node in a network runs out of energy). In a typical setting, we assume broadcast traffic that is generated by one (more generally: a subset) of the nodes. The two main issues discussed during the talk are problems and solutions relating to (1) the settings of the transmission powers of the nodes; and (2) the set of relay nodes (nodes that forward the traffic on the multi-hop path from one node to its destination(s)). For the first aspect, we assume the transmission powers to be variable, one aim is to reduce the transmit powers as much as possible, without losing connectivity of the network. The second aspect is the selection of relay nodes. In a multi-hop network these are the nodes on a path from the source to a destination. If there are multiple paths from a source to a destination then these can be alternated, taking into account the remaining battery capacity of the nodes, in order to maximize the network lifetime.