However it is important to curb the energy expenditure due
13 Chapter 1 Design of Large-scale Sensor Networks
Aravind Iyer et al.
to (i) idle-listening in MAC protocols, and due to (ii) the control message
exchanges for the routing and MAC protocols. Also, for such networks, it is
reasonable to assume that there would be no data destined for an individual
sensor device. As discussed in Subsection 3.3, there might be a need for the
sink to communicate with all the sensors for reconfiguration. But due to the
infrequency of sensor events, the volume of this tra?±c is expected to be very
low, if at all. Following are some of the important design challenges for this
class of applications:
Lightweight Addressing
In general, there is a need for addressing in a sensor network for the following
three purposes: (i) MAC, (ii) routing, and (iii) location information to tag the
data. The traditional mechanism for addressing is to use a unique per-node
identifier which can be mapped and used at all the three levels. However,
owing to the large number of nodes in many sensor networks, using strict pernode
addressing is wasteful. Not only would the size of an address be large,
but also these addresses would need to be allocated and exchanged at di?®erent
layers of the protocol stack. Besides, as noted in Subsection 3.3, sensor
networks follow the many-to-one paradigm of communication. So it is unlikely
that any two sensors would want to communicate with each other.
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