This will also change the underlying topology of the network. A natural question
is then how to assign the transmission power for each node such that
the wireless sensor network is connected (or with other nice properties) with
optimization criteria minimizing the maximum (or total) transmission power
assigned. Much research has been done in this area [98, 99, 101??“105].
Another related problem is power management in sensor networks. Remember
that power is the critical issue in sensor networks, therefore network
lifetime can be prolonged by using smart power management techniques. The
most common power management technique is turning o?® the radio of the
inactive sensor node to save power. However, sensor networks require nodes
to forward packets for other nodes. Therefore, there is a tradeo?® between energy
conservation and network performance. The goal of power management
is turning o?® as many nodes as possible without significantly diminishing the
capacity or connectivity of the network. Several power management protocols
[106??“108] have been proposed. The main assumption of all these power
management protocols is high density of sensors.
Due to the various applications of sensor networks, the topology control
design is also various. For example, Pan et al [109] considered a two-tiered
wireless sensor network consisting of sensor clusters deployed around strategic
locations and base-stations (BSs) whose locations are relatively flexible.
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