08-16-2017, 10:00 PM
Described here is the notion of a network-on-a-chip: a programmable, asynchronous VLSI architecture for fast and efficient simulation of wireless networks. Wireless sensor networks have high potential economic
impact in many fields, including military, education,
monitoring, retail, and science. low power, low cost, small size,
error and fault resiliency, flexibility, security and
privacy are other features.
networks and asynchronous VLSI are starkingly similar. Network simulators
like OPNET aid designers in determining whether a particular protocol change would improve the overall behavior of the network.A wireless channel is more complex than a traditional wired transmission channel in that messages sent by different entities to distinct destinations can interfere with one another. Wireless network
simulators like OPNET include modules that model these additional properties.Analysis of individual components on SN nodes
(processor, communication, storage, sensors, actuators,
and power supply), node level and networked system
level are done.
Individual Components of SN Nodes
SN nodes have six components: processor, storage
unit, radio, sensors, actuators, and power supply
subsystems.
Processor
It provides processing capabilities and includes a standard processor,
possibly supplemented with DSP and other co-processors
and some ASIC units.
Storage:
It depends on the architecture. there is very little need for local
storage on each individual node if one follows the
architecture where all information is instantaneously sent
to the central node. there will be significant requirement
for local storage in architectures aiming significantly less communication. Flash memory is very attractive in terms
of cost and storage capacity. nano-electronics -
based MRAM is also used.
Power Supply.
each sensor node can be added with a (rechargeable) source of energy.
The widely taken option is to use high-density
battery cells. Full cells provide
exceptional high density and clean source of energy.Other sources like
solar cells,
converting vibration to electric energy are also being considered.
Sensors.
The sensing technologies
are not progressing as fast as semi-conductors. Transducers are front-end components in sensor nodes
which are being used to transform one form of energy into
another. quantity of sensors and
their placement is a challenge. Most of the times, more than one
sensor type is needed to ensure the correctness of
operation and data from different sensor that can be
combined.
Radios.
They do the sending and receiving of messages. The physical, media access control
(MAC), and network layers have to be considered while designing the radios. Often several radios have to share the
same interconnect medium. In this situation, there is a
need for coordinated access policy.
Wireless SNs as Embedded Systems
the wireless sensor networks is the
widely used cellular wireless network. In this
architecture, a number of base stations are already
deployed within the field.Each base atation(cell) covers a certain part of the area. Mobile wireless
nodes and other appliances can communicate wirelessly,
as long as they are at least within the area covered by one
cell. In the wireless multihop ad-hoc
networks , a definite architecture is not needed and the nodes can configure themselves to communicate to other nodes within their
communication range on the fly. If two nodes that are not
within each other's range need to communicate to each
other, they use the intermediate nodes as the relays.