Mobile Ad Hoc on Demand Data Delivery Ro (1)
Mobile Ad Hoc on Demand Data Delivery Routing Protocol
In the proceedings of the 3rd Annual Post-Graduate Symposium on the Convergence of
Telecommunications, Networking and Broadcasting, June 2002, Liverpool, UK.
Humayun Bakht, Madji d Merabti, and Bob Askwith
School of Computing and Mathematics
Liverpool John Moores Univeristy
Byrom Street, Liverpool L3 3AF, UK
Email: {cmshbakh, M.Merabti, R.Askwith} @livjm.ac.uk
Abstract
Routing in mobile adhoc network is an unresolved
issue. Much effort has been undergoing to invent a
mechanism for achieving efficient and reliable
routing in mobile adhoc networks. In this paper we
presented a routing algorithm at very abstract level
for mobile adhoc networks. The proposed
algorithm adopts an intermediate approach in
between the two existing techniques i.e. Table
driven and on demand routing.
We believe, efficient routing in mobile adhoc
network could be achieved if route discovery and
data delivery could occur at the same time, based
on the presented algorithm a more advance form
could be develop which would be helpful in
providing a effective solution for the routing
problem of mobile adhoc networks.
1) Introduction
Mobile adhoc networks are relatively a new field,
which is mainly used in a dynamic or unpredictable
environment. These types of networks give
opportunity for users to enjoy networking facilities
where either there is no fixed network
infrastructure available or to make one is not cost
effective.
Mobile Ad hoc networking is an advantageous way
of exchanging peer-to-peer information among
different types of network devices such as fixed,
portable and mobile nodes. The use of these
network are increased dramatically and are being in
use for implementing solutions for business,
entertainment and safety applications in the office,
residential and industrial areas. The key
characteristic of a mobile ad hoc network is the
ability of any node to route traffic for other nodes.
Ad-hoc network is a collection of mobile nodes
connected together forming a communication
network without any centralized support. The
problem here relates to how mobile hosts can
communicate with one other, over the wireless
media, in the absence of any fixed infra structured.
To provide communication ability, a routing
protocol must be able to support unicast, multicast
and broadcast.
Existing Internet protocols are specifically
designed for fixed networks, i.e. some supporting
structure. These protocols are not therefore well
suited for mobile adhoc networks; therefore there is
a need of inventing some new mechanism for
supporting routing in mobile adhoc network.
Routing in mobile adhoc network is a growing
research topic in wireless networks research
community. There are a number of protocols,
which have been specifically designed for mobile
adhoc networks. Examples of some early work in
this area is [1,2] while some current effort could be
found in [3,4]. These protocols do not work well in
all environments [5], which suggest more efficient
techniques need to be developed for mobile adhoc
networks.
In an ad-hoc network all nodes cooperate each
other in order to dynamically establish and
maintain routing in the network, forwarding
packets for each other to allow communication
between nodes not directly within wireless
transmission range. Rather then using then using
the periodic or background exchange of routing
information common in most routing protocols.
One traditional way of achieving routing in mobile
adhoc network is to consider each host as a router.
In mobile adhoc network a route between a pair of
mobile nodes may go through several other mobile
nodes. These routes can change when hosts change
location. Therefore a good amount of research has
been done in this area for both unicast routing [6]
and multicast routing [7,8,9] of mobile adhoc
networks, also a significant amount of research
[10,11,12,13] has been done addressing routing
problem in mobile adhoc networks.
2) Related Work
This paper presents a new algorithm for routing in
mobile adhoc network. The interest in these types
of network is growing due to the widely available
license-free wireless communication devices that
users of laptop computers can use to communicate
with each other.
Link state routing is one of the old way of
acquiring routing in mobile adhoc network, based
on broadcast, in this type of routing each node
maintains information on the state of the links
established between the other nodes in the network.
However link state routing is very expensive
especially in terms of bandwidth. Current protocols
for mobile adhoc networks are based on one of two
main techniques, table driven and on demand. In
Table driven routing nodes attempts to maintain a
consistent overview of the network by requiring
periodic updates, it records all information in the
routing tables, which is use whenever a
transmission is required. On Demand protocols
discover a route only on demand i.e. eliminate the
need of routing table and updates. We believe if
one side routing table in table driven protocols can
be helpful in effective and fast transmission on the
other hand it causes Updates overhead, especially
in presence of high mobility, large routing tables,
low scalability which results in consummation of
bandwidth and battery life. In On Demand protocol
[14] there are number of advantages such as
reducing control overhead, increasing bandwidth
and conserving power at the mobile station,
However these networks are relatively slow i.e.
may not be appropriate for real time
communication, Bottleneck may occur due to
latency of route discovery. Most of the work done
so far in this field is either based on or extension
one of these two techniques.
One other type of existing routing techniques is
GPS-enabled Adhoc routing algorithm, In this
types of routing nodes are equipped with positing
system devices (e.g. Global positioning System
receivers) that make them aware of their position,
this enable “directional” routing, however
positional solution differ on how the location
information of the destination could be achieved.
Some of the draw back of this technique are, need
extra hardware, depends on the extra hardware
limitation and scalability.
Hence the problems associated with the existing
schemes motivate us to describe a better routing
approach to support mobile adhoc networks.
3) Proposed Protocol
We want our protocol inherited the best
characteristics from table driven and from on
demand protocols. When the local connectivity of
the mobile nodes is of interest each mobile node
can become aware of the other nodes in its
neighbourhood by the use of one of several
techniques such as broadcasting hello messages.
The routing tables of the nodes within the
neighbour hood are organized and each node
update it table with the received information such
as sequence number and hop count to all other
nodes in the network.
Some of the primary objective of purposed
algorithm is as follows.
n
n
n
n
Broadcast information to deliver data only
when requires (On demand data delivery)
To provide fast effective means of
transmission (Deliver data as soon as
destination is found)
Minimizing the battery power usage
Minimizing bandwidth usage
Any node wants to deliver data to any other node in
the network invoke the route discovery and data
delivery process very similar to on demand
protocols however it differs in some respects,
which are as follows.
There are three possibilities when a node broadcast
some data packet
1)
2)
3)
Either it reached to any intermediate node,
which on receiving it transfer it to the
destination.
Destination it self
Un- delivers and returned to the source.
3.1) Basic Mechanism
Each node in the network maintains a routing
table, which recorded destination IP address,
Destination Sequence number, hop count to
destination and next hop for routes to other
nodes in the network. New entries are placed
in the route table following the reception of
hello message, issued by the node on joining
the network, route request and data delivery
process.
In our proposed algorithm source node does
not need to wait to hear from the destination or
the intermediate node. Whenever a node
wants to transmit some data to any other node
in the network. It first looks in to its routing
table if it has route information for the
destination node? If it does not have route
information for the destination it invokes the
route discovery and data delivery process, as
soon as this data packet reach to any
intermediate node having route to the
destination or the destination it self, it is
delivered to the destination. If the packet does
not reach to destination it is marked as
undelivered and returned to the source node;
which forward this message to all other nodes
in the network; This node is then recorded as
invalid or inactive, a sequence number of ∞ is
assign to it while sequence numbers of all
other nodes are rearranged accordingly.
The proposed algorithm can be separated into
three basic functions, route discovery and data
delivery process, route table management and
local connectivity management. Creating a
route from a given node to destination node
requires establishment of a sequence of links
from the source to the destination. The method
use to accomplish this is route discovery and
data delivery process, in which not only route
discovery is done but also transferring of data
to other node is performed. Routing tables are
used to hold the information about other nodes
in the network while local connectivity
management is required to keep update with
the current status of all other neighbouring
nodes. Detail description of each process is as
follows.
3.2) Route Discovery and Data Delivery
Process
The path discovery process is very similar to
Adhoc on demand distance vector protocol and
it initiated whenever a source node needs to
communicate with another node for which it
has no routing information in its table. Every
node maintains two separate pieces of
information: a node sequence number and a
broadcast_id. The source node initiates route
discovery and data delivery process by
broadcasting a route request (RREQ) + (Data)
packet to its neighbours. The RREQ contains
the following fields.
The
pair
uniquely identified a RREQ. Broadcast_id is
incremented each time source issue a new
process. Each neighbour on receiving this
message performs the following two functions.
First of all it recorded the sequence number
and next hop information for the source node.
Secondly it look into the routing table weather
it has a route to the destination or not if it has
route it forward the packet to the destination
otherwise broadcast this packet to the closest
neighbour in its table. Any intermediate node
before forward the packet to the destination
makes sure that the route is current by
comprising the destination sequence number in
its own route entry to the destination sequence
number in the RREQ however if the broadcastid and source address is similar to the one it
has received before it simply ignore the request
and does not rebroadcast it. This process
continues until either the packet reach to the
destination or it returned to the source node as
undelivered.
3.3)
Route Table Management
In addition to the source and destination sequence
numbers, other useful information is stored in the
route table entries. In each route table entry the
address of active neighbours through which packets
for the given destination are received is also
maintained. A route entry in the route table is
recorded active if use by any other active neighbour
which is followed by the acknowledge packet from
the destination.
A mobile node maintains a route table entry for
each destination of interest. Each route table entry
contains the following information.
n
n
n
n
Destination address
Next Hop
Sequence number for the destination
Active neighbours for this route
If a new route is offered to a mobile node, the
mobile node compares the destination sequence
number of the new route to the destination
sequence number of the current route.
3.4) Local Connectivity Management
A Node can adopt two ways to know about its
neighbours. Whenever a node receive a broadcast
from a neighbour its updates its local connectivity
information to ensure that it includes this
neighbours. In the event when the node is not in
transmission, it itself can broadcast a hello message
to inform all other nodes about it status.
4) Analysis and Discussion
After reviewing all the existing techniques we
found if on one hand continues updates could
create network overhead on the other hand route
discovery for each transmission is not very feasible
either. In the case of adhoc network where changes
in topology is unpredictable it is relatively very
difficult to always get the successful route
discovered via route discovery mechanism. We
therefore suggested rather then performing route
discovery task for route discovery the similar
process could be invokes to deliver the data
directly to the destination instead. We consider this
approach more feasible to adopt because one of
following reasons.
n
It does not require keeping consistent
overview of the network as in the case of
link state protocols. Thus does not create
unnecessary network overhead.
n
Some on demand protocols such as
AODV and DSR [15] uses periodic
beaconing to keep routing table updated
thus adding a significant overhead to the
protocol where’s in the case our
proposed algorithm, No periodic updates
is require as the proposed algorithm
discover route to deliver the data only
when requires.
n
n
n
In the case of existing on demand
protocol by the time a suitable route
establish
between a source and
destination there is a chance of link
failure or topology changes between any
of these two nodes or by an intermediate
node which could results either in
transmission failure or invoke route
maintenance mechanism, Therefore we
can avoid this situation by delivering the
packets directly to the destination node.
It is not always true especially in mobile
adhoc networks that all the routes are
always valid no matter weather recorded
in the routing table or by caching. So
even if a source node has a valid route
recorded (link state) or cache (on
demand) it is not necessary there is no
guarantee that the route will always be
available throughout the transmission or
some time even for a single successful
transmission, By giving freedom of
choice to all nodes to transfer the packet
to the destination either if they a link to
the destination or rebroadcast it until the
route is found eliminates possibility of
route invalidity. As if the destination
node is in the transmission range and
still active the data will be transfer
otherwise would be returned to the
source node as undelivered.
Route discovery creates unnecessary
time delay thus effects the overall
performance of the network, which make
on demand existing protocols unsuitable
for real time communication, Where’s
our proposed protocol does not require
route to be established before being
transfer the packet and thus make it
possible
to
achieve
real
time
communication.
n
A Bottleneck occurs either when the
node send query packet to discover the
best possible route to the destination
node or it issues a route error messages.
We believe the possibility of bottleneck
could be minimize by adopting our
algorithm.
n
We like to emphasize, that though we do
adopt routing table strategy of link state
protocols but does not depend entirely
on the recorded information, we used
these information as a starting point
instead and to returned the undelivered
data packet.
n
In our approach, we do not suggest any
route maintenance mechanism however
in the case when the source node could
not discover the data it can retransmit it
if require.
n
Based on the availability issue some
protocol such as global positioning
system enable protocol requires use of
global positioning system receiver for
directional routing in mobile ad hoc
network. However in our approach no
extra hardwire is required.
In the light of the above discussion it can
easily be realized that this approach is an
does not require continuous updates, it does
not require route discovery process for each
transmission,
no
route
maintenance
mechanism is required, does not create
network overhead and no extra hardware is
needed, which prove it as a bandwidth
efficient, minimize battery usage and a
reliable algorithm.
5) Further Work
In this paper we presented our thoughts by
considering the existing work in the area of routing
in mobile adhoc networks, and in effort to develop
some new techniques that can be helpful to
accomplish successful and reliable routing in
mobile adhoc networks. As mentioned earlier
current existing table driven and on demand
protocols does not work well in all environments,
which impose a challenge of developing some new
protocols which not only full fill the basic routing
requirement of on demand protocols but also shows
significant results in different types of
environment.
Some of the fundamental task in accomplish the
final product is to evaluate the performance of both
proactive and reactive protocols, although
extensive comparisons are available for proactive
and reactive protocols but our research shows these
comparison mainly based on numerical results and
there is a lack of analytical results available in this
area. This comparison is very important as we
regard as one of the most important in successful
implementation of our routing protocol. We are
particularly interested in the functionality of Ad
hoc on demand routing protocol, as most of the
function of our proposed protocol is very similar to
it.
Mobility, bandwidths and battery life are some of
the important miles stones in achieving efficient
routing in mobile adhoc networks. Minimizing
energy consumption is an important challenge in
mobile computing. Mobility causes variation
between the lifetimes of two hosts. And limited
bandwidth makes a network to be easily congested
by control signalling, we consider these issues as
some of the important issue, Our proposed protocol
could be use to minimize bandwidth usage and to
give battery a longer life. However a series of test
needs to be done in order to obtain a clear view
about the over all performance of the protocol i.e.
up to what extend it could minimize the bandwidth
usage and maximize the battery life.
Multicast routing and packet forwarding in mobile
adhoc network is a fairly unexplored. Since fixed
network multicast routing is based on state in
routers, it is fundamentally unsuitable for an AHN
environment with unconstrained mobility. Our own
going work looking into possibility of extending
the initial model of the proposed protocol to
support both unicast and multicast routing.
The above discussion gives a picture of our longterm research plan, Once implemented, we believe
our protocol will be able to provide a reliable and
efficient mechanism for routing in mobile adhoc
networks.
6) Conclusion
We have proposed a routing algorithm, based on
the idea of route discovery and data delivery at the
same time. We believe the algorithm could be well
suited for operation in mobile adhoc network. The
main features of proposed protocol are as follows
n
n
n
n
n
Established routes and deliver data at the
same time.
All routes are loop- free through the use of
destination sequence numbers.
Discover route and deliver data at the
same time
Inactive routes can easily be identified.
Does not require periodic updates
n
n
n
n
Reduce network overhead
Minimize bandwidth usage
Increase battery life.
Provide real time communication
Efficient routing could be achieved if source does
not need to wait to establish route to the destination
rather then it invoke route discovery and data
delivery process at the same time. This algorithm
can be utilize to minimize bandwidth, maximize
the battery life and to achieve fast reliable
transmission when require.
7) References
[1]
D. B. Jhonson, “Routing in Ad-Hoc
Networks of Mobile Hosts,” Proceedings of the
IEEE Workshop on Mobile Computing Systems
and Applications, Dec. 1994.
[2]
S.Murthy and J. J. Carcia -Luna-Aceves,
“A Routing Protocol for Packet Radio Networks,”
1st ACM International Conference on Mobile
Computing and Networking (Mobicom 95), pp. 8695, 1995.
[3]
Y. Ko and N. H. Vaidya, “GeoTORA: A
Protocol for Geocasting in Mobile Ad Hoc
Networks,” 8th International Conference on
Network Protocols (ICNP), Osaka,, November
2000.
[4]
Y.-C. Hu and D. B. Johnson, “Caching
Strategies in On Demand Routing Protocols for
Wireless Ad Hoc Networks,” To appear in
Proceedings of the Sixth Annual International
Conference on Mobile Computing and Networking,
August 6-11,2000, Boston, MA, USA., 2000.
[5]
N. Vaidya., “Tutorial on Mobile Ad Hoc
Networks: Routing, MAC and Transport Issues,”
2001 MobiCom (Rome) and 2000 MobiCom
(Boston), 2000.
[6]
B. S., I. Chlamtac, and V. R. Syrotiuk,
“Dynamic Source Routing for Ad Hoc Networks
Using the Global Positioning System,” Proceedings
of the IEEE Wireless Communications and
Networking Conference 1999 (WCNC'99),New
Orleans, LA,, September 21-24, 1999.
[7]
E. M. Royer and C. E. Perkins, “Multicast
Operation of the Ad-hoc On-Demand Distance
Vector Routing Protocol,” Proceedings of
MobiCom '99, 1999.
[8]
E. L, Madruga, and J.J.Garcia-LunaAceves, “Multicasting Along Meshes in Ad-Hoc
Networks,” Proc. IEEE ICC '99 Vancouver,
Canada, June 6--10, 1999.
[9]
S. Lee and C. Kim, “A new Wireless ad
hoc multicast routing protocol,” Comp uter
Networks, pp. 121-135, 5 June 2001.
[10]
K. Obraczka and G. Tsudik, “Multicasting
Routing Issues in Ad Hoc Networks,”
IEEE
International Conference on Universal Personal
Communication (ICUPC'98), Oct. 1998.
[11]
E. Royer and C.-K. Toh, “A Review of
Current Routing Protocols for Ad-Hoc Mobile
Wireless
Networks,”
IEEE
Personal
Communications Magazine, pp. 46-55, April 1999.
[12]
E. M. Royer, S.-J. Lee, and C. E. Perkins,
“The Effects of MAC Protocols on Ad hoc
Network Communication,” IEEE WCNC 2000,
September 2000.
[13]
C.-K. Toh, “A Novel Distributed Routing
Protocol To Support Ad-Hoc Mobile Computing,”
Proceedings of 15th IEEE Annual International
,Phoenix
Conference
on
Computers
and
Communications, pp. 480-486, 1996.
[14]
C. E. Perkins and E. M. Royer, “Ad-hoc
On-Demand
Distance
Vector
Routing,”
Proceedings of the 2nd IEEE Workshop on Mobile
Computing Systems and Applications, pp. pp. 90100, February 1999.
[15]
G. Aggelou and R. Tafazolli, “RDMAR:
A bandwidth-effiecent Routing Protocol for Mobile
Adhoc Network,” In Proceedings of ACM
MobiCom99/WoWMoM99 , Washington, USA,
August 1999.
In the proceedings of the 3rd Annual Post-Graduate Symposium on the Convergence of
Telecommunications, Networking and Broadcasting, June 2002, Liverpool, UK.
Humayun Bakht, Madji d Merabti, and Bob Askwith
School of Computing and Mathematics
Liverpool John Moores Univeristy
Byrom Street, Liverpool L3 3AF, UK
Email: {cmshbakh, M.Merabti, R.Askwith} @livjm.ac.uk
Abstract
Routing in mobile adhoc network is an unresolved
issue. Much effort has been undergoing to invent a
mechanism for achieving efficient and reliable
routing in mobile adhoc networks. In this paper we
presented a routing algorithm at very abstract level
for mobile adhoc networks. The proposed
algorithm adopts an intermediate approach in
between the two existing techniques i.e. Table
driven and on demand routing.
We believe, efficient routing in mobile adhoc
network could be achieved if route discovery and
data delivery could occur at the same time, based
on the presented algorithm a more advance form
could be develop which would be helpful in
providing a effective solution for the routing
problem of mobile adhoc networks.
1) Introduction
Mobile adhoc networks are relatively a new field,
which is mainly used in a dynamic or unpredictable
environment. These types of networks give
opportunity for users to enjoy networking facilities
where either there is no fixed network
infrastructure available or to make one is not cost
effective.
Mobile Ad hoc networking is an advantageous way
of exchanging peer-to-peer information among
different types of network devices such as fixed,
portable and mobile nodes. The use of these
network are increased dramatically and are being in
use for implementing solutions for business,
entertainment and safety applications in the office,
residential and industrial areas. The key
characteristic of a mobile ad hoc network is the
ability of any node to route traffic for other nodes.
Ad-hoc network is a collection of mobile nodes
connected together forming a communication
network without any centralized support. The
problem here relates to how mobile hosts can
communicate with one other, over the wireless
media, in the absence of any fixed infra structured.
To provide communication ability, a routing
protocol must be able to support unicast, multicast
and broadcast.
Existing Internet protocols are specifically
designed for fixed networks, i.e. some supporting
structure. These protocols are not therefore well
suited for mobile adhoc networks; therefore there is
a need of inventing some new mechanism for
supporting routing in mobile adhoc network.
Routing in mobile adhoc network is a growing
research topic in wireless networks research
community. There are a number of protocols,
which have been specifically designed for mobile
adhoc networks. Examples of some early work in
this area is [1,2] while some current effort could be
found in [3,4]. These protocols do not work well in
all environments [5], which suggest more efficient
techniques need to be developed for mobile adhoc
networks.
In an ad-hoc network all nodes cooperate each
other in order to dynamically establish and
maintain routing in the network, forwarding
packets for each other to allow communication
between nodes not directly within wireless
transmission range. Rather then using then using
the periodic or background exchange of routing
information common in most routing protocols.
One traditional way of achieving routing in mobile
adhoc network is to consider each host as a router.
In mobile adhoc network a route between a pair of
mobile nodes may go through several other mobile
nodes. These routes can change when hosts change
location. Therefore a good amount of research has
been done in this area for both unicast routing [6]
and multicast routing [7,8,9] of mobile adhoc
networks, also a significant amount of research
[10,11,12,13] has been done addressing routing
problem in mobile adhoc networks.
2) Related Work
This paper presents a new algorithm for routing in
mobile adhoc network. The interest in these types
of network is growing due to the widely available
license-free wireless communication devices that
users of laptop computers can use to communicate
with each other.
Link state routing is one of the old way of
acquiring routing in mobile adhoc network, based
on broadcast, in this type of routing each node
maintains information on the state of the links
established between the other nodes in the network.
However link state routing is very expensive
especially in terms of bandwidth. Current protocols
for mobile adhoc networks are based on one of two
main techniques, table driven and on demand. In
Table driven routing nodes attempts to maintain a
consistent overview of the network by requiring
periodic updates, it records all information in the
routing tables, which is use whenever a
transmission is required. On Demand protocols
discover a route only on demand i.e. eliminate the
need of routing table and updates. We believe if
one side routing table in table driven protocols can
be helpful in effective and fast transmission on the
other hand it causes Updates overhead, especially
in presence of high mobility, large routing tables,
low scalability which results in consummation of
bandwidth and battery life. In On Demand protocol
[14] there are number of advantages such as
reducing control overhead, increasing bandwidth
and conserving power at the mobile station,
However these networks are relatively slow i.e.
may not be appropriate for real time
communication, Bottleneck may occur due to
latency of route discovery. Most of the work done
so far in this field is either based on or extension
one of these two techniques.
One other type of existing routing techniques is
GPS-enabled Adhoc routing algorithm, In this
types of routing nodes are equipped with positing
system devices (e.g. Global positioning System
receivers) that make them aware of their position,
this enable “directional” routing, however
positional solution differ on how the location
information of the destination could be achieved.
Some of the draw back of this technique are, need
extra hardware, depends on the extra hardware
limitation and scalability.
Hence the problems associated with the existing
schemes motivate us to describe a better routing
approach to support mobile adhoc networks.
3) Proposed Protocol
We want our protocol inherited the best
characteristics from table driven and from on
demand protocols. When the local connectivity of
the mobile nodes is of interest each mobile node
can become aware of the other nodes in its
neighbourhood by the use of one of several
techniques such as broadcasting hello messages.
The routing tables of the nodes within the
neighbour hood are organized and each node
update it table with the received information such
as sequence number and hop count to all other
nodes in the network.
Some of the primary objective of purposed
algorithm is as follows.
n
n
n
n
Broadcast information to deliver data only
when requires (On demand data delivery)
To provide fast effective means of
transmission (Deliver data as soon as
destination is found)
Minimizing the battery power usage
Minimizing bandwidth usage
Any node wants to deliver data to any other node in
the network invoke the route discovery and data
delivery process very similar to on demand
protocols however it differs in some respects,
which are as follows.
There are three possibilities when a node broadcast
some data packet
1)
2)
3)
Either it reached to any intermediate node,
which on receiving it transfer it to the
destination.
Destination it self
Un- delivers and returned to the source.
3.1) Basic Mechanism
Each node in the network maintains a routing
table, which recorded destination IP address,
Destination Sequence number, hop count to
destination and next hop for routes to other
nodes in the network. New entries are placed
in the route table following the reception of
hello message, issued by the node on joining
the network, route request and data delivery
process.
In our proposed algorithm source node does
not need to wait to hear from the destination or
the intermediate node. Whenever a node
wants to transmit some data to any other node
in the network. It first looks in to its routing
table if it has route information for the
destination node? If it does not have route
information for the destination it invokes the
route discovery and data delivery process, as
soon as this data packet reach to any
intermediate node having route to the
destination or the destination it self, it is
delivered to the destination. If the packet does
not reach to destination it is marked as
undelivered and returned to the source node;
which forward this message to all other nodes
in the network; This node is then recorded as
invalid or inactive, a sequence number of ∞ is
assign to it while sequence numbers of all
other nodes are rearranged accordingly.
The proposed algorithm can be separated into
three basic functions, route discovery and data
delivery process, route table management and
local connectivity management. Creating a
route from a given node to destination node
requires establishment of a sequence of links
from the source to the destination. The method
use to accomplish this is route discovery and
data delivery process, in which not only route
discovery is done but also transferring of data
to other node is performed. Routing tables are
used to hold the information about other nodes
in the network while local connectivity
management is required to keep update with
the current status of all other neighbouring
nodes. Detail description of each process is as
follows.
3.2) Route Discovery and Data Delivery
Process
The path discovery process is very similar to
Adhoc on demand distance vector protocol and
it initiated whenever a source node needs to
communicate with another node for which it
has no routing information in its table. Every
node maintains two separate pieces of
information: a node sequence number and a
broadcast_id. The source node initiates route
discovery and data delivery process by
broadcasting a route request (RREQ) + (Data)
packet to its neighbours. The RREQ contains
the following fields.
The
pair
uniquely identified a RREQ. Broadcast_id is
incremented each time source issue a new
process. Each neighbour on receiving this
message performs the following two functions.
First of all it recorded the sequence number
and next hop information for the source node.
Secondly it look into the routing table weather
it has a route to the destination or not if it has
route it forward the packet to the destination
otherwise broadcast this packet to the closest
neighbour in its table. Any intermediate node
before forward the packet to the destination
makes sure that the route is current by
comprising the destination sequence number in
its own route entry to the destination sequence
number in the RREQ however if the broadcastid and source address is similar to the one it
has received before it simply ignore the request
and does not rebroadcast it. This process
continues until either the packet reach to the
destination or it returned to the source node as
undelivered.
3.3)
Route Table Management
In addition to the source and destination sequence
numbers, other useful information is stored in the
route table entries. In each route table entry the
address of active neighbours through which packets
for the given destination are received is also
maintained. A route entry in the route table is
recorded active if use by any other active neighbour
which is followed by the acknowledge packet from
the destination.
A mobile node maintains a route table entry for
each destination of interest. Each route table entry
contains the following information.
n
n
n
n
Destination address
Next Hop
Sequence number for the destination
Active neighbours for this route
If a new route is offered to a mobile node, the
mobile node compares the destination sequence
number of the new route to the destination
sequence number of the current route.
3.4) Local Connectivity Management
A Node can adopt two ways to know about its
neighbours. Whenever a node receive a broadcast
from a neighbour its updates its local connectivity
information to ensure that it includes this
neighbours. In the event when the node is not in
transmission, it itself can broadcast a hello message
to inform all other nodes about it status.
4) Analysis and Discussion
After reviewing all the existing techniques we
found if on one hand continues updates could
create network overhead on the other hand route
discovery for each transmission is not very feasible
either. In the case of adhoc network where changes
in topology is unpredictable it is relatively very
difficult to always get the successful route
discovered via route discovery mechanism. We
therefore suggested rather then performing route
discovery task for route discovery the similar
process could be invokes to deliver the data
directly to the destination instead. We consider this
approach more feasible to adopt because one of
following reasons.
n
It does not require keeping consistent
overview of the network as in the case of
link state protocols. Thus does not create
unnecessary network overhead.
n
Some on demand protocols such as
AODV and DSR [15] uses periodic
beaconing to keep routing table updated
thus adding a significant overhead to the
protocol where’s in the case our
proposed algorithm, No periodic updates
is require as the proposed algorithm
discover route to deliver the data only
when requires.
n
n
n
In the case of existing on demand
protocol by the time a suitable route
establish
between a source and
destination there is a chance of link
failure or topology changes between any
of these two nodes or by an intermediate
node which could results either in
transmission failure or invoke route
maintenance mechanism, Therefore we
can avoid this situation by delivering the
packets directly to the destination node.
It is not always true especially in mobile
adhoc networks that all the routes are
always valid no matter weather recorded
in the routing table or by caching. So
even if a source node has a valid route
recorded (link state) or cache (on
demand) it is not necessary there is no
guarantee that the route will always be
available throughout the transmission or
some time even for a single successful
transmission, By giving freedom of
choice to all nodes to transfer the packet
to the destination either if they a link to
the destination or rebroadcast it until the
route is found eliminates possibility of
route invalidity. As if the destination
node is in the transmission range and
still active the data will be transfer
otherwise would be returned to the
source node as undelivered.
Route discovery creates unnecessary
time delay thus effects the overall
performance of the network, which make
on demand existing protocols unsuitable
for real time communication, Where’s
our proposed protocol does not require
route to be established before being
transfer the packet and thus make it
possible
to
achieve
real
time
communication.
n
A Bottleneck occurs either when the
node send query packet to discover the
best possible route to the destination
node or it issues a route error messages.
We believe the possibility of bottleneck
could be minimize by adopting our
algorithm.
n
We like to emphasize, that though we do
adopt routing table strategy of link state
protocols but does not depend entirely
on the recorded information, we used
these information as a starting point
instead and to returned the undelivered
data packet.
n
In our approach, we do not suggest any
route maintenance mechanism however
in the case when the source node could
not discover the data it can retransmit it
if require.
n
Based on the availability issue some
protocol such as global positioning
system enable protocol requires use of
global positioning system receiver for
directional routing in mobile ad hoc
network. However in our approach no
extra hardwire is required.
In the light of the above discussion it can
easily be realized that this approach is an
does not require continuous updates, it does
not require route discovery process for each
transmission,
no
route
maintenance
mechanism is required, does not create
network overhead and no extra hardware is
needed, which prove it as a bandwidth
efficient, minimize battery usage and a
reliable algorithm.
5) Further Work
In this paper we presented our thoughts by
considering the existing work in the area of routing
in mobile adhoc networks, and in effort to develop
some new techniques that can be helpful to
accomplish successful and reliable routing in
mobile adhoc networks. As mentioned earlier
current existing table driven and on demand
protocols does not work well in all environments,
which impose a challenge of developing some new
protocols which not only full fill the basic routing
requirement of on demand protocols but also shows
significant results in different types of
environment.
Some of the fundamental task in accomplish the
final product is to evaluate the performance of both
proactive and reactive protocols, although
extensive comparisons are available for proactive
and reactive protocols but our research shows these
comparison mainly based on numerical results and
there is a lack of analytical results available in this
area. This comparison is very important as we
regard as one of the most important in successful
implementation of our routing protocol. We are
particularly interested in the functionality of Ad
hoc on demand routing protocol, as most of the
function of our proposed protocol is very similar to
it.
Mobility, bandwidths and battery life are some of
the important miles stones in achieving efficient
routing in mobile adhoc networks. Minimizing
energy consumption is an important challenge in
mobile computing. Mobility causes variation
between the lifetimes of two hosts. And limited
bandwidth makes a network to be easily congested
by control signalling, we consider these issues as
some of the important issue, Our proposed protocol
could be use to minimize bandwidth usage and to
give battery a longer life. However a series of test
needs to be done in order to obtain a clear view
about the over all performance of the protocol i.e.
up to what extend it could minimize the bandwidth
usage and maximize the battery life.
Multicast routing and packet forwarding in mobile
adhoc network is a fairly unexplored. Since fixed
network multicast routing is based on state in
routers, it is fundamentally unsuitable for an AHN
environment with unconstrained mobility. Our own
going work looking into possibility of extending
the initial model of the proposed protocol to
support both unicast and multicast routing.
The above discussion gives a picture of our longterm research plan, Once implemented, we believe
our protocol will be able to provide a reliable and
efficient mechanism for routing in mobile adhoc
networks.
6) Conclusion
We have proposed a routing algorithm, based on
the idea of route discovery and data delivery at the
same time. We believe the algorithm could be well
suited for operation in mobile adhoc network. The
main features of proposed protocol are as follows
n
n
n
n
n
Established routes and deliver data at the
same time.
All routes are loop- free through the use of
destination sequence numbers.
Discover route and deliver data at the
same time
Inactive routes can easily be identified.
Does not require periodic updates
n
n
n
n
Reduce network overhead
Minimize bandwidth usage
Increase battery life.
Provide real time communication
Efficient routing could be achieved if source does
not need to wait to establish route to the destination
rather then it invoke route discovery and data
delivery process at the same time. This algorithm
can be utilize to minimize bandwidth, maximize
the battery life and to achieve fast reliable
transmission when require.
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