DESIGN ISSUES
·
The wireless link characteristics are
time-varying in nature: There are transmission impediments like fading, path
loss, blockage and interference that adds to the susceptible behaviour of
wireless channels. The reliability of wireless transmission is resisted by
different factors.
·
Limited range of wireless
transmission – The limited radio band results in reduced data rates compared to
the wireless networks. Hence optimal usage of bandwidth is necessary by keeping
low overhead as possible.
·
Packet losses due to errors in
transmission – MANETs experience higher packet loss due to factors such as
hidden terminals that results in collisions, wireless channel issues (high bit
error rate (BER)), interference, frequent breakage in paths caused by mobility
of nodes, increased collisions due to the presence of hidden terminals and
uni-directional links.
·
Route changes due to mobility- The
dynamic nature of network topology results in frequent path breaks.
·
Frequent network partitions- The
random movement of nodes often leads to partition of the network. This mostly
affects the intermediate nodes.
·
Limited bandwidth: Wireless link continue to have
significantly lower capacity than infra structured networks. In addition, the
realized throughput of wireless communication after accounting for the effect
of multiple access, fading, noise, and interference conditions, etc., is often
much less than a radio‘s maximum transmission rate.
·
Dynamic topology: Dynamic topology membership may
disturb the trust relationship among nodes. The trust may also be disturbed if
some nodes are detected as compromised.
·
Routing Overhead: In wireless adhoc networks, nodes
often change their location within network. So, some stale routes are generated
in the routing table which leads to unnecessary routing overhead.
·
Hidden terminal problem: The hidden terminal
problem refers to the collision of packets at a receiving node due to the
simultaneous transmission of those nodes that are not within the direct
transmission range of the sender, but are within the transmission range of the
receiver.
·
Packet losses due to transmission errors: Ad hoc
wireless networks experiences a much higher packet loss due to factors such as
increased collisions due to the presence of hidden terminals, presence of
interference, uni-directional links, frequent path breaks due to mobility of
nodes.
·
Mobility-induced route changes: The network
topology in an ad hoc wireless network is highly dynamic due to the movement of
nodes; hence an on-going session suffers frequent path breaks. This situation
often leads to frequent route changes.
·
Battery constraints: Devices used in these networks
have restrictions on the power source in order to maintain portability, size
and weight of the device.
·
Security threats: The wireless mobile ad hoc nature
of MANETs brings new security challenges to the network design. As the wireless
medium is vulnerable to eavesdropping and ad hoc network functionality is
established through node cooperation, mobile ad hoc networks are intrinsically
exposed to numerous security attacks.
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