Networking Reference
In-Depth Information
one of the major design considerations that should be taken care of in any protocol
designed for such networks including the routing ones. Routing protocols designed
for such networks should include mechanisms to conserve node energy to prolong
the lifetime of the nodes and of the network as a whole. Examples of such tech-
niques are data aggregation, use of meta-data, load balancing, restricted flooding,
use of energy-aware metrics, use of a resource manager, and putting nodes into
sleep mode.
(a) Data Aggregation
Data aggregation is one of the techniques that is highly utilized in the energy-
efficient routing protocols because, when deployed, it has a great impact on the
nodes' residual energy and lifetime. The idea is that instead of sending
redundant packets or packets that have a kind of correlation, these packets can
be combined and aggregated together into only one packet. Reducing the
number of transmitted packets leads to great conservation in node energy.
(b) Use of Meta-Data
A number of protocols depend on sending meta-data that describes the actual
data packets instead of sending the actual packets themselves. This technique
is mainly used for advertising the actual data. Instead of sending long data
packets to nodes that may not be interested in them, small meta-data is sent to
advertise the acquired data packets and if a node shows its interest in such
data, the complete data packet is sent to it afterwards.
(c) Load Balancing
Many protocols focus on balancing the traffic load among the nodes in order
not to overload some nodes compared to others which may lead to depletion of
these nodes' batteries and cause their failures. For example, in cluster-based
routing protocols, if cluster formation is static and not changed throughout the
network life, the nodes that act as cluster-heads will burn their energy quickly,
and after they die, all their members will be ''headless'' and therefore useless.
This is because the role of being a cluster-head is energy consuming as the
cluster-head has to be awake all the time, receive data from all of its cluster
members, incur processing overhead for aggregating the data, and is respon-
sible for the long-range transmissions to the data collector. To provide energy
efficiency and balance energy consumption among the nodes, some routing
protocols utilize dynamic clustering to rotate the role of being a cluster-head
among the nodes.
(d) Restricted Flooding
When a packet needs to be broadcast (e.g., route request packets or data
interests), some protocols make use of restricted flooding instead of flooding
the packet to the whole network. For example, the packet can be sent to a
group of nodes with higher probability to forward the packet or with wider
coverage and view for the network. Another example is forwarding the packet
to an area of interest instead of to the whole network, for example, sending
data interests geographically to the area of interest then flooding the interest
only within this area.
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