21-04-2012, 10:58 AM
Classification of Ad Hoc Routing Protocols
[attachment=20498]
Introduction
Ad hoc network is a multi-hop wireless network, which
consists of number of mobile nodes. These nodes
generate traffic to be forwarded to some other nodes or a
group of nodes. Due to a dynamic nature of ad hoc
networks, traditional fixed network routing protocols are
not viable. Based on that reason several proposals for
routing protocols has been presented.
Ad hoc radio networks have various implementation
areas. Some areas to be mentioned are military,
emergency, conferencing and sensor applications. Each
of these application areas has their specific requirements
for routing protocols. For example in military
applications low probability of detection and interception
is a key factor such is routing efficiency during fading
and disturbed radio channel conditions.
A Taxonomy for Routing Protocols
Because of multiple and diverse ad hoc protocols there is
an obvious need for a general taxonomy to classify
protocols considered. Traditional classification is to
divide protocols to table-driven and to source-initiated
on-demand driven protocols [1].
Table-driven routing protocols try to maintain consistent,
up-to-date routing information from each node to every
other node. Network nodes maintain one or many tables
for routing information. Nodes respond to network
topology changes by propagating route updates
throughout the network to maintain a consistent network
view.
State Information
Protocols may be described in terms of the state
information obtained at each node and / or exchanged
among nodes. Topology-based protocols use the
principle that every node in a network maintains largescale
topology information. This principle is just the
same as link-state protocols use.
Destination-based protocols do not maintain large-scale
topology information. They only may maintain topology
information needed to know the nearest neighbors. The
best known such protocols are distance-vector protocols,
which maintain a distance and a vector to a destination
(hop count or other metric and next hop).
Scheduling
The way to obtain route information can be a continuous
or a regular procedure or it can be trigged only by on
demand. On that basis the protocols can be classified to
proactive and on-demand protocols. Proactive
protocols, which are also know as table-driven
protocols, maintain all the time routing information for
all known destinations at every source. In these protocols
nodes exchange route information periodically and / or
in response to topology change.
Partitioning Protocol
CEDAR
Core Extraction Distributed Ad hoc Routing (CEDAR)
[12] is a partitioning protocol, emphasizing QoS support.
Each partition includes a core node. The core nodes use
a reactive source routing protocol to outline a route from
a source to a destination.
Applicability of different Protocols
Evaluation criteria
Different kind of ad hoc routing protocols are suitable
for different kind of network structures and node
behaviors. When evaluating protocols one needs some
appropriate classification also for the features of
performance metrics.
The critical features for ad hoc networks can be
classified according to Subbaro [19] to following
quantitative and qualitative features. Quantitative
features are:
- Network settling time, which is the time for a
network to reach a stable state and be able to
send its first message reliably.
- Network join time, which is the time for an
entering node or group of nodes to become
integrated into the ad hoc network.
- Network depart time , which is the time
required for the ad hoc network to recognize the
loss of one or more nodes, and reorganize itself
to manage lacking links.
- Network recovery time, which is the time for a
network to recover after a condition that
dictates reorganization of the network.
- Frequency of updates, which is the number of
control packets or overhead bytes inside packets
to be sent in a given time to maintain proper
network operation. This means also same as
overhead.
Conclusion
As it can be seen, there is vast number of different kinds
of protocols. Only minority of the presented protocols
will attain a technical or commercial success, one would
forecast. Each of these protocols has some common
goals. Every protocol has the ability of distributed
routing calculations and every protocol try to manage the
consequences caused by mobility of nodes. But the
means are such different as they can be.
[attachment=20498]
Introduction
Ad hoc network is a multi-hop wireless network, which
consists of number of mobile nodes. These nodes
generate traffic to be forwarded to some other nodes or a
group of nodes. Due to a dynamic nature of ad hoc
networks, traditional fixed network routing protocols are
not viable. Based on that reason several proposals for
routing protocols has been presented.
Ad hoc radio networks have various implementation
areas. Some areas to be mentioned are military,
emergency, conferencing and sensor applications. Each
of these application areas has their specific requirements
for routing protocols. For example in military
applications low probability of detection and interception
is a key factor such is routing efficiency during fading
and disturbed radio channel conditions.
A Taxonomy for Routing Protocols
Because of multiple and diverse ad hoc protocols there is
an obvious need for a general taxonomy to classify
protocols considered. Traditional classification is to
divide protocols to table-driven and to source-initiated
on-demand driven protocols [1].
Table-driven routing protocols try to maintain consistent,
up-to-date routing information from each node to every
other node. Network nodes maintain one or many tables
for routing information. Nodes respond to network
topology changes by propagating route updates
throughout the network to maintain a consistent network
view.
State Information
Protocols may be described in terms of the state
information obtained at each node and / or exchanged
among nodes. Topology-based protocols use the
principle that every node in a network maintains largescale
topology information. This principle is just the
same as link-state protocols use.
Destination-based protocols do not maintain large-scale
topology information. They only may maintain topology
information needed to know the nearest neighbors. The
best known such protocols are distance-vector protocols,
which maintain a distance and a vector to a destination
(hop count or other metric and next hop).
Scheduling
The way to obtain route information can be a continuous
or a regular procedure or it can be trigged only by on
demand. On that basis the protocols can be classified to
proactive and on-demand protocols. Proactive
protocols, which are also know as table-driven
protocols, maintain all the time routing information for
all known destinations at every source. In these protocols
nodes exchange route information periodically and / or
in response to topology change.
Partitioning Protocol
CEDAR
Core Extraction Distributed Ad hoc Routing (CEDAR)
[12] is a partitioning protocol, emphasizing QoS support.
Each partition includes a core node. The core nodes use
a reactive source routing protocol to outline a route from
a source to a destination.
Applicability of different Protocols
Evaluation criteria
Different kind of ad hoc routing protocols are suitable
for different kind of network structures and node
behaviors. When evaluating protocols one needs some
appropriate classification also for the features of
performance metrics.
The critical features for ad hoc networks can be
classified according to Subbaro [19] to following
quantitative and qualitative features. Quantitative
features are:
- Network settling time, which is the time for a
network to reach a stable state and be able to
send its first message reliably.
- Network join time, which is the time for an
entering node or group of nodes to become
integrated into the ad hoc network.
- Network depart time , which is the time
required for the ad hoc network to recognize the
loss of one or more nodes, and reorganize itself
to manage lacking links.
- Network recovery time, which is the time for a
network to recover after a condition that
dictates reorganization of the network.
- Frequency of updates, which is the number of
control packets or overhead bytes inside packets
to be sent in a given time to maintain proper
network operation. This means also same as
overhead.
Conclusion
As it can be seen, there is vast number of different kinds
of protocols. Only minority of the presented protocols
will attain a technical or commercial success, one would
forecast. Each of these protocols has some common
goals. Every protocol has the ability of distributed
routing calculations and every protocol try to manage the
consequences caused by mobility of nodes. But the
means are such different as they can be.