zone based ant colony routing in manet[report]
DESCRIPTION
seminar report on zone based ant colony optimization.TRANSCRIPT
1Zone Based Ant Colony Routing In MANET
1. INTRODUCTION.............................................................................................................................3
2. OVERVIEW OF ANT COLONY ROUTING ALGORITHM.........................................................................4
2.1 The Shortest Path Problem In A Real Ant Colony.........................................................................4
3. POSANT ROUTING ALGORITHM.....................................................................................................6
3.1 Zones In Posant:..........................................................................................................................6
3.2 Route Establishment In Posant:...................................................................................................7
4. ZONE BASED ANT ROUTING USING CLUSTER................................................................................9
4.1 Phases Of Zone Based Clustering Algorithm................................................................................9
4.1.1) Max-Min D-Cluster Formation Algorithm...........................................................................9
4.1.2) Zone Formation algorithm:...............................................................................................11
4.1.3) Cluster Maintenance protocol using GPS technology.......................................................12
4.2 Route Establishment Procedure of Zone based ANT Colony:....................................................13
4.2.1) Route establishment Algorithm of Zone based ANT Colony:............................................14
4.2.2) Route establishment Flow Chart of Zone based ANT Colony:...........................................15
5. COMPARATIVE STUDY OF OVERHEAD OF POSANT WITH THAT OF ZONE BASED ANT COLONY ROUTING.............................................................................................................................................16
5.1) Overhead Comparison..............................................................................................................16
5.2. HOP Count Comparison............................................................................................................18
5.3 Delay Comparison.....................................................................................................................19
5.4 Throughput Comparison............................................................................................................19
5.5. Advantage of Zone based ANT colony over POSANT:...............................................................21
6.CONCLUSION....................................................................................................................................22
REFERENCES........................................................................................................................................23
2Zone Based Ant Colony Routing In MANET
1. INTRODUCTION
Wireless Sensor Network is a collection of wireless, uniquely addressable sensor devices hich
dynamically form a temporary network, without using any existing network infrastructure or
centralized administration. Each node in the network effectively becomes a router, and
orwards packets towards the packet’s destination node.Wireless sensor networks are
characterized by frequently changing network topology, multi-hop wireless connection and
the need of dynamic, efficient routing protocols. . Routing is a major challenging problem in
mobile adhoc networks because of mobile nodes, unstable links and limited resources.
Ant colony optimization (ACO) is a stochastic approach for solving combinatorial
optimization problems like routing in computer networks. The idea of this optimization is
based on the food accumulation methodology of the ant community. Zone based routing
algorithms is build on the concept of individual node’s position for routing of packets in
mobile ad-hoc networks. Here the nodes’ position can be further utilized to discover routes
by the Ants in optimized way. Position based routing algorithms (POSANT) had some
significant loopholes to find route like it never guarantees the route would be the shortest one,
in cases while it is able to find it. The routing algorithms which are based on ant colony
optimization find routing paths that are close in length to the shortest paths. The drawback of
these algorithms is the large number of control messages that needs to be sent or the long
delay before the routes are established from a source to a destination.
This paper describes Zone based Ant Colony routing algorithm using Cluster in mobile ad-
hoc network, which assures to find shortest route using the DIR principle. In this principle,
the source or intermediate node transmits message to several neighbours and the node whose
direction is closest to the direction of destination gets selected as the next hop forwarding
node,together with minimum overhead for route discovery and mobility management. Unlike
other Zone based approach, in clustering it is not required to consider zone related
information of each node while finding shortest path. This algorithm combines the concept of
Ant Colony approach and Zone based routing approach using clustering to get shortest path
with small number of control messages to minimize the overhead.It uses the concept of
clustering in mobile ad-hoc network. Those clusters will be controlled by cluster heads.
3Zone Based Ant Colony Routing In MANET
2. OVERVIEW OF ANT COLONY ROUTING ALGORITHM
Ant colony algorithm (ACO) is a stochastic approach for solving combinatorial optimization
problems like routing in computer networks.ACO is distributed and adaptive in finding
shortest paths from source to destination nodes while also constructing a low cost overlay
routing network. The idea of this optimization is based on the observation of how ants
optimize food gathering in the nature. Each node can take itself some stochastic decision
based on some specific attributes supplied to the node .
Ant colony algorithms get there inspiration from the behaviour of real ants gathering for
food. Individual ants act as simple agents that hunt for food by following pheromone trails
and depositing pheromone along the path taken. An ant is more likely to follow a trail with a
high concentration of pheromone. Pheromone on shorter paths gets increasingly reinforced as
more ants follow the higher concentration of pheromones. This is due to more ants being able
to travel a shorter path than a longer path over a given period of time .
2.1 The Shortest Path Problem In A Real Ant Colony
A real ant colony is able to find food and follow the shortest path from the nest to the food.
As a real ant moves, it deposits a substance called pheromone on the ground. When an ant
reaches a point that has more than one outgoing branch, the probability that a branch will be
selected by an ant is dependent on the amount of pheromone deposited on each branch. An
ant will select a branch and deposit more pheromone on this branch; as a result, the
probability of selecting this branch will increase. The pheromone on the branches of the
shortest path to the food will grow faster than pheromone on other branches. The pheromone
is evaporated over time, allowing the system to forget old paths and helping to avoid quick
convergence to a sub-optimal solution. To highlight how the ant colony finds the shortest
path, an example is described in Fig. 1.
Figure 1.ant colony shortest path problem
4Zone Based Ant Colony Routing In MANET
In Fig. 1-a, two ants at the nest need to reach the food. No pheromone is originally placed on
the two paths .Each ant selects one of the two paths randomly. The Ants deposit pheromone
trails while moving (Fig. 1-b). The ant that selected the shortest path will arrive first; pick up
the food and returns back following the path with highest pheromone. In this case, ant B will
reach the food first (Fig. I-c) and, in its way back, it will select the path it came from since it
has the highest pheromone and at the same time deposits more pheromone as seen in(FigI-
d).Now when ant A reaches the food, it will also follow ant B’s path since this path has more
pheromone and deposits more pheromone, thus enforcing more the selection of this path.
Gradually, the pheromone on the shortest path will increase as shown in (Fig 1-e).
A single ant is not intelligent, but the ant colony can find the shortest path. As the ants search
for the shortest path, they explore many paths. The longest paths and unexplored paths still
have a probability to be visited. If the shortest path fails, a recently explored path will be
followed by the ants. Even if , the first ants used the longer path, the ant colony is able to find
the shortest one as the pheromone evaporates with time and the shortest path still has a
probability to be visited.The real ant colony is a dynamic self-built and self configured
system, which is capable of solving its problems efficiently. These features of real ant colony
system are matching the requirements of the MANETs. By pheromone reinforcement, the
path used from the source node to the destination node attracts more ants and data packets.
As time passes, the pheromone concentration on theshorter path will be higher than that on
the longer path, because the ants using the shorter path will increase the pheromone
concentration faster. The shortest path will thus be identified and will become the only path
used by all ants eventually. This leads to a problem, called stagnation. In pheromone control,
there are several approaches, such as evaporation, aging and limiting and smoothing
pheromone. Evaporation is used to reduce the effect of past experience and aging is used for
controlling the amount of pheromone deposited for each ant according to its age. Limiting is
a scheme that sets maximum pheromone value to be deposited to make the preference of an
ant for optimal paths over nonoptimal paths is reduced.Pheromone smoothing places a
relatively greater reduction in the reinforcement of pheromone concentration on the optimal
paths. Pheromone-heuristic control uses not only the deposited pheromone value but also
heuristic function to choose the next hop.
5Zone Based Ant Colony Routing In MANET
3. POSANT ROUTING ALGORITHM
In position based routing algorithm the destination node is known and addressed by means of
its location. Routing is performed by a scheme that is based on this information, which is
generally classified as position-based scheme.POSANT is ant colony optimization based
routing algorithm which uses location information to improve its efficiency. POSANT is able
to find optimum or nearly optimum routes when a given network contains nodes.
3.1 Zones In Posant:
Consider a destination node D and a network graph G. For each node S,we partition its
neighbours into 3 zones called zone1, zone2 and zone3. Consider a line segment between S
to D. For a neighbours H of S, angle θH is defined as the angle between line segments SH
and SD. Node H belongs to zone1 if θH ≤ π/4, zone2 if π/4 < θH < 3π/4, and zone3 if 3π/4 ≤
θH ≤ π, see Fig below.
Figure 2 Different zones of network N for destination node D
3.1.a Zone Selection Algorithm of POSANT:
if (abs(θH) >= z5)
θH = abs(θH) - z5;
if(((abs(θH) < z1) && (abs(θH) >= 0.0)) || ((abs(θH) > z4) &&
(abs(θH) <= z5)))
6Zone Based Ant Colony Routing In MANET
ret = 1;
elseif (((abs(θH) < z2) && (abs(θH) >= z1)) || ((abs(θH) > z3)
&& (abs(θH) <= z4)))
ret = 2;
elseif((abs(θH) <= z3) && (abs(θH) >= z2))
ret = 3;
return ret;
Where, z5 = 2π, z4 = 7π/4, z3 = 5π/4, z2 = 3π/4, z1 = π/4.
3.2 Route Establishment In Posant:
Consider a set of data packets coming to source node S where the destination address is D. To
establish a route, S launches n forward ants with unique sequence numbers for each zone (3n
ants). Assigning very large value to n increases the overhead of the algorithm without any
significant improvement. Similar to other ACO routing algorithms, at each node a forward
ant makes a stochastic decision which is based on the values of pheromone trails to select the
next hop.The values of pheromone trails are stored in a table called pheromone trail table at
each node according to the zone value of the particular node.
Suppose that a forward ant is currently residing in node S and this node has k neighbours H1,
H2,...,Hk. Among them let H1, H2,..., Hi are in Zone 1, Hi1, Hi2,...,Hj are in Zone 2 and Hj1,
Hj2…. Hk are in Zone 3. S launches 3 ants in each zone. The ant in zone 1 will take
stochastic decision to find the next hop depending upon value of pheromone trail of its
outgoing link. As discussed above, value of pheromone trail of zone 1 will be greater than
that of other zone. So ant will follow the zone 1 go get the shortest path. Similarly, ants of
zone 2 and zone 3 will follow the path of 2nd and 3rd priority.
In the Figure below, according to the POSANT concept, ant of zone 1 chooses A as next hop
and it follows path Source -> A -> B -> L. But the path comes to a dead end and ant 1 lost
because it already traverse node B and no other path is there from node l. But the ant of zone
2 gets the path from source to destination.
7Zone Based Ant Colony Routing In MANET
Figure 3.Traversal of ants in each zone
In addition to the pheromone trail table discussed above, each node maintains another table
which we call Back Routing (BR) table. Whenever a forward ant enters a node from one of
its neighbours, an entry in the BR table will be created that stores the identifier of the
neighbour which the forward ant is coming from, the sequence number of the ant and the
identifier of the destination. Repeated forward ants will be destroyed. When a forward ant
reaches the destination, it is destroyed and a backward ant is sent back to the source. This
backward ant has the same sequence number as the corresponding forward ant and traverses
the same path to the source using the information stored in BR tables. Moving from node B to
node A, the backward ant increases the amount of pheromone stored in AB. An evaporation
process causes the amount of pheromone deposited in each link to decrease as the time passes
on .
8Zone Based Ant Colony Routing In MANET
4. ZONE BASED ANT ROUTING USING CLUSTER
Clustering means grouping of nodes in the network. This grouping depends upon
transmission range and number of hop in a group. Each node group will have a group head
called Cluster head having the responsibility of communication among its member nodes and
other cluster heads. Cluster head should contain address of its member nodes as well as that
of other cluster heads. Member nodes need to store address information of their cluster head
and neighbour nodes. When information needs to pass from one node to another, member
node sends this information to its corresponding cluster head, which decides whether the
destination is a member or not. If yes, it directly sends the information to destination. If no, it
sends the information alone with the destination node to other cluster heads which then start
to search in their own cluster.
4.1 Phases Of Zone Based Clustering Algorithm
The Zone Based Clusering Algorithm has three major phases,and they are:
Phase I :Cluster Formation
Phase II : Zone Formation
Phase III : Mobility Management of Cluster Heads through Selection of Surrogate
Heads
4.1.1) Max-Min D-Cluster Formation Algorithm
The heuristic has four logical stages:
1. Propagation of larger node ids via floodmax,
2. Propagation of smaller node ids via floodmin,
3. Determination of clusterheads,
4. The linking of clusters.
Initial Cluster formation:
At the time of initialization of this algorithm, transmission range and number of hop (d)
should be mentioned so that cluster can be formed and cluster heads can be selected for those
clusters.
Data Structures
The heuristic runs for 2d rounds of information exchange. Each node maintains two
arrays,WINNER and SENDER, each of size 2d node ids: one id per round of information
exchange.The WINNER is the winning node id of a particular round and used to determine
9Zone Based Ant Colony Routing In MANET
the clusterhead for a node.The SENDER is the node that sent the winning node id for a
particular round and is used to determine the shortest path back to the clusterhead, once the
clusterhead is selected.
Basic Idea
Initially, each node sets its WINNER to be equal to its own node id. This is followed by the
Floodmax phase.
Floodmax
Each node locally broadcasts its WINNER value to all of its 1-hop neighbours. After all
neighbouring nodes have been heard from, for a single round, the node chooses the largest
value among its own WINNER value and the values received in the round as its new
WINNER. This process continues for d rounds.
Floodmin
This follows Floodmax and also lasts d rounds. It is the same as Floodmax except a node
chooses the smallest rather than the largest value as its new WINNER
Algorithm:
Step I: At some common epoch each node initiates 2d rounds of flooding of
information exchange (node id) where d is the given heuristic. In this algorithm,
flooding occurs once, at the time of initial cluster formation. Each node maintains a
logged entry of two arrays, WINNER and SENDER to store the results of each
flooding round.
Step II: Initially each node sets its winner to be equal to its own node id.
Step III: This is the phase for FLOODMAX where a node chooses the largest value
among its own WINNER array and this process continues for d rounds.
Step IV: This FLOODMIN phase follows FLOODMAX where a node chooses the
smallest rather than the largest value as its new WINNER.
Step V: After these two d rounds of information exchange a node is able to determine
its cluster-head .
Figure below shows the clusters formed when the heuristic terminates.
10Zone Based Ant Colony Routing In MANET
Figure 4. cluster formation in a network of 25 nodes.
4.1.2) Zone Formation algorithm:
Step I: The cluster head broadcasts get_Position_forAll ( ) request message along
with its own GPS to get percolated within d hop.
Step II: All member nodes in turn unicast back the message node_GPS ( ) to the
cluster-head using geographical routing.
11Zone Based Ant Colony Routing In MANET
Step III: Cluster-head receives all the GPS values of its members and calculates
the maximum limiting coordinates for Left, Right, Up and Down values to define
its boundary.
Step IV: The cluster head then broadcasts the message get_Boundary_values ( )
within the d hop transmission range to notify all the member nodes about the
cluster boundary.
Step IV: All the member nodes become alerted about the rectangular cluster
boundary information, which can be verified while changing their positions and
these geographical formed boundaries are considered as zones.
4.1.3) Cluster Maintenance protocol using GPS technology
In ad hoc networks, because node can move arbitrarily, any node can leave its cluster
boundary. The problem of node mobility is much more alarming when the cluster head itself
becomes mobile and thereby generating the necessity of periodic re-clustering.In the cluster
management protocol any node including the cluster head automatically gets alarmed while
crossing the geographical boundary of a cluster using the cluster management protocol.There
is a program that continuously compares the current GPS value of the node with that of
boundary values. Thus it is quite easy for a departing cluster head to make a timely
arrangement for rebinding with new cluster head and unbind with old one. The cluster head
can select any of its current cluster members for delegating the cluster headship and thus can
handover the entire cluster head responsibility to facilitate the process of data
communication.This paper considers two different schemes for selecting surrogate head.
If surrogate head can be selected from the middle of the cluster then, the chance of
this new cluster head to cross the cluster boundary gets reduced and as such the
duration of a node to remain as cluster head increases, but the traffic overhead
involved for handover of headship is much higher due to multihop data transfer.
In the second scheme, when the departing head can select any of its 1-hop neighbours
as surrogate head and as such there is no need to concern about their position. Here
the initial overhead for data transfer is much less due to 1-hop data transfer.But as the
surrogate head lies within the vicinity of cluster boundary the chance of change of
cluster head in near future also gets increased.
This entire process of using surrogate head highly reduces the need for cluster head
reelection and there by decreasing the network traffic load involved. When any cluster head
crosses its boundary, surrogate head will be chosen to take the responsibility of the departing
12Zone Based Ant Colony Routing In MANET
cluster head. Thus there is no requirement of repetition of flooding for the purpose of
reclustering.So, at the time of overhead calculation we need to consider flooding overhead
once that is, only during the initial cluster formation.
4.2 Route Establishment Procedure of Zone based ANT Colony:
Consider the source node S in Figure 4, has a set of data packets which should be forwarded
to the destination node D.S will contact with its Cluster head to confirm whether the
destination node is within the same cluster. If yes, then data packet is directed towards the
destination node through the cluster head.If the destination node is not in the same cluster of
the source node, then cluster head of the source node creates n – 1 number of forward ants
with unique sequence number and send those ants to each and every reachable cluster
heads.Here n is the number of reachable clusters from the source’s cluster head including its
own cluster. Whenever a forward ant enters a node from one of its neighbours, an entry in the
Backward Routing table will be created..After getting destination id from the forward ants,
each cluster head start searching the destination id within its member list. If any of the cluster
heads finds that the destination id is its member node, then it destroys the forward ant and
creates backward ant. This backward ant has the same sequence number as the corresponding
forward ant and traverses the same path to the source using the information stored in
Backward Routing tables.
Figure 5.Zone based Ant Colony Routing using Clustering concept.
13Zone Based Ant Colony Routing In MANET
4.2.1) Route establishment Algorithm of Zone based ANT Colony:
Let us assume that, Source S has message M to send the destination node D. Then the Route
establishment Algorithm steps are:
1. S unicast data-packet DP to ClusterHead(S) [Data Packet DP consists of Destination
Node address + Message M which need to be delivered to D].
2. CH(S) searches its Member List Table to see if D is a member of CH(S)
3. If CH(S) finds that D is its own member, send feedback to S and deliver the message
M to D
4. If CH(S) finds that D is not its own member, CH(S) generates (n-1) forward ants with
unique sequence numbers to send them to (n-1) reachable Cluster heads through
multi-hop paths.
5. Each forward Ant, is forwarded towards boundary nodes of Cluster(S).
6. From these boundary nodes, forward Ants are sent to those neighbour nodes, which
are boundary nodes of other clusters.
7. From this boundary nodes of other clusters, forward ants travels to the Cluster head of
other Clusters.
8. When forward Ant comes to a Cluster head, sequence number of this forward ant is
stored in this Cluster head to keep track of duplicate entry.
9. Each Cluster head checks the sequence number of the forward ant and see if it already
has the sequence stored in it.If no, it searches its Member List Table to see if D is its
member. Otherwise it kills the forward and as it has already searches for this ant.
Thus this algorithm avoids loops.
10. When any of the Cluster heads finds that D is its member, it kills the forward Ant and
generates Backward Ant with same sequence number.
11. Cluster head which has D as its member node,delivers the message M to D.
12. Then sends back the Backward Ant to the Source node S as a feedback.
13. When a Cluster head finds that D is not its member,it sends the forward ant to its
neighbour cluster to search.
14Zone Based Ant Colony Routing In MANET
4.2.2) Route establishment Flow Chart of Zone based ANT Colony:
Figure 6.Route establishment Flow Chart of Zone based ANT Colony
Abbreviation used in the Flow Chart:
DP: Data Packet. CH(S): Cluster head of Source Node. T: Total number of cluster heads
BN: Boundary Notes. FAnt: Forward Ant
Cnt: Counter. When forward Ant comes to a CH, this counter should be increased by 1.
Seq no: Unique sequence number of ant.
15Zone Based Ant Colony Routing In MANET
5. COMPARATIVE STUDY OF OVERHEAD OF POSANT WITH THAT OF ZONE BASED ANT COLONY ROUTING
In POSANT algorithm the overhead is coming from three paths that have been considered
there between source to destination node. Total overhead in POSANT should be sum of
overhead of all the paths. In Zone based Ant Colony, if source and destination node are not in
the same zone then cluster head of the source node will send ants to all other cluster heads to
find the destination node. So, if n number of zones formed in the network, n number of
cluster heads will be there and (n – 1) number of ants will be sent by source cluster head to all
other cluster heads, so total over head will be sum of overhead of all (n-1) paths.
5.1) Overhead Comparison
a) By varying Zone size:
In Zone based ANT colony using clustering, we can increase the Zone size by increasing the
HOP value of cluster value. Thus, by increasing zone size we can reduce number of zones in
this network. By reducing number of zones we can reduce the number of forward ants which
will be sent from source cluster head to all other reachable cluster head to find out the
destination node’s cluster head. So, in other word we can reduce overhead of forwarding ants
in zone based ANT colony by increasing HOP value. Though it will not affect overhead of
POSANT as it does not depends upon HOP value.Fig. 6 shows the comparison table and
graph between POSANT and Zone based ANT colony with varying HOP value.
Figure 7. Zone size Vs Overhead
16Zone Based Ant Colony Routing In MANET
b) By varying Node Number:
In Zone based ANT colony when number of nodes will be increased, more number of nodes
will be there in each zone and will increase zone concentration and will be taken care by
corresponding cluster head. As here HOP value D is fixed,number of zones and zone size will
not be increased. So,number of ants traversing from one cluster head to another cluster head
will not be increased. Only concentration of node within each zone will be creased. It may
increase responsibility of each cluster head but at the same time increment of overhead will
be less than that of POSANT. In POSANT when number of nodes is increased ANT needs to
traverse more number of nodes to reach the destination node.Fig. below shows the graph
representing the comparison between POSANT and Zone based ANT colony with varying
node number.
Figure 8. Number of Node Vs Overhead
c) By varying Mobility:
In case of Zone based ANT colony, when the destination node will leave its zone due to
mobility and enter into a new zone, previous cluster head will reply back to the source’s
cluster head that destination node is not its member node.After getting this message, source
cluster head will forward ants towards all reachable cluster heads to know the current zone of
destination node. Where as in POSANT, source node will come to know the location change
information of the destination node or any other node in the path from source to destination
after a certain period (time out period) when the sender of the source node will not get any
acknowledgement message from the receiver of destination node. After realizing that, source
node again have to start POSANT algorithm by sending ants in three zones as mentioned
above. As POSANT algorithm needs more overhead to execute than of Zone based ANT
colony, mobility factor affect POSANT much more than Zone based ANT colony. Fig. shows
17Zone Based Ant Colony Routing In MANET
the graph representing the comparison between POSANT and Zone based ANT colony with
varying node number.
Figure 9. Mobility Vs Overhead:
5.2. HOP Count Comparison
a) By varying number of nodes
In Zone based ANT colony when we increase number of nodes ant has to traverse more of
nodes, only concentration of zone will be increased. As here HOP value is fixed, zone size
will not be increased.Number of zones will also be unchanged. So, number of ants traversing
from one cluster head to another cluster head will not be increased. As zone concentration
will be increased, ant has to traverse more number of nodes within the zone of destination
node. Whereas in POSANT, increment of number of nodes will result increment of HOP
count for the entire network. As a result ant has to traverse more number of HOP.Fig. shows
the graph representing the comparison between POSANT and Zone based ANT colony with
varying node number.
Figure 10 Number of Node Vs HOP Count:
18Zone Based Ant Colony Routing In MANET
b) By varying mobility:
In Zone based ANT colony, while location of destination node or any other member node
changes, Cluster head gets this information and guide ants to go to right direction. Where as
in case of POSANT, when position of node changes due to mobility, ants need to start
searching in the three zones again from the scratch. So, increment of mobility causes much
more increment of HOP count in case of POSANT than Zone based ANT colony.Fig. shows
the comparison table and graph between POSANT and Zone based ANT colony with varying
mobility.
Figure 11 Mobility Vs HOP Count:
5.3 Delay Comparison
In a network, if the diameter of the network increases or the density of node increases, ant or
data packet needs to traverse more number of HOP to reach the destination and that causes
increase in processing delay at each node. Thus the overall delay in delivering the data
packets gets increased. So we can ay that delay is proportional to HOP Count of a
network.Simulation results of HOP count can throw light on the variation of delay in the
network
5.4 Throughput Comparison
a) By varying number of nodes
In POSANT, when number of node increases, concentration of the whole network increases.
In case of Zone based Ant colony, when number of node increases, number of zones and zone
size will remains same. But concentration of each zone will be increased. So when Ant
traverses in a zone with higher concentration, the probability of getting lost will be decreases.
19Zone Based Ant Colony Routing In MANET
That increases throughput.Fig. shows the comparison table and graph between POSANT and
Zone based ANT colony with varying node number.
Figure 12 Number of Node Vs Throughput:
b) By varying Mobility:
In Zone based ANT colony, while location of destination node or any other member node
changes, Cluster head gets this information and guide ants to go to right direction. Where as
in case of POSANT, when position of node changes due to mobility, ants need to start
searching in the three zones again from the scratch which causes more data loss. So,
increment of mobility causes much more decrement of throughput in case of POSANT than
Zone based ANT colony.Fig. shows the comparison table and graph between POSANT and
Zone based ANT colony with varying mobility.
Figure 13 : Mobility Vs Throughput:
20Zone Based Ant Colony Routing In MANET
5.5. Advantage of Zone based ANT colony over POSANT:
This algorithm will provide advantage of both ant colony and zone based algorithm. Like ant
colony algorithm, here we need not store large routing tables in nodes, we need to store only
neighbouring node information and previous traversed node information. As nodes in mobile
ad-hoc network will have memory of small storage capacity, it would be tough to store large
routing table inside each node. In our zone based ant colony algorithm there will be cluster
head available within each zone. As clustering concept, only cluster head node need to store
path information of its member nodes as well as zone boundary information for all other
clusters in the network.In POSANT routing, like all other position based routing,source node
need to know the position of the destination node.Robustness is a problem in position based
ant colony algorithm. The use of position of destination node causes problem in terms of
reliability.
Overhead
Overhead of Zone based ANT colony is much less than that of POSANT,
Increment of overhead due to increment of node number and mobility is much
more in POSANT than that of Zone based Ant system. Decrement of overhead
due to increment of HOP value is much more in Zone based ant system than that
of POSANT.
HOP Count
HOP Count of Zone based ANT colony is less than of POSANT, as we can see
from the results of simulations on varying Number of nodes, Mobility and Zone
Size (HOP value).
Throughput
Throughput of Zone based ANT colony is better than of POSANT, because in
Zone Based Algorithm, data packets need not traverse to each individual node.
Cluster heads will decide whether data packets should traverse to a particular zone
or not. So chances of loss are less than of POSANT.
21Zone Based Ant Colony Routing In MANET
6.CONCLUSION
Zone based routing using ant colony optimization aims to support zone based routing with
minimum routing overhead for mobile ad hoc networks. The idea behind this zone based
routing is to allow the nodes within each zone to get referred with the zone boundaries and
control the node. Ant Colony technique merged with Zone based technique to optimize
memory utilization, overhead and throughput.In zone based routing, each zone member is
aware of its mobility using the zone boundary values. It allows the node to inform about their
mobility and thereby enabling the protocol to find the mobile destination quickly with
minimum overhead. A cluster head is available within each zone to perform data transmission
and routing. The performance analysis shows that, in highly mobile network, Zone based ant
colony reduces overhead, Hop value and increases throughput than POSANT in all three
cases (varying node number,mobility and Zone size). So in conclusion, we can say that Zone
based ANT colony is better than POSANT.
Future Work
Zone Based ANT Colony routing algorithm, always uses shortest path for routing the data
packets. Ants always traverse the shortest path from source to destination through the source
cluster head and destination cluster head using geographical shortest path forwarding
technique. So here always the shortest path is selected for routing and load balancing concept
has not been incorporated in this routing algorithm.Load balancing can be introduced by
selecting second shortest path sometimes in case we have large number of data packets to
send so that the same set of nodes should not remain selected in the route path always. Thus
load balancing can also be handled in Zone based Ant colony algorithm. This can be
implemented as a future work.
22Zone Based Ant Colony Routing In MANET
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