ADHOC NETWORK THROUGHPUT ENHANCEMENT

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Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


7


ADHOC NETWORK THROUGHPUT ENHANCEMENT

Asim Shahzad,

K
urram Zeeshan Haider, Qamas Gul Khan Safi




Abstract


Ad hoc networking is emerging as
todays

and future requirement

for dynamic and
mobile
wireless
communication.
For fast
connections

the refugee node
needs a path
where it can avail the best

throughput by
means of connections created
on the fly, for
single time usage or on short
-
term basis.

In
this paper we have focused on the scenario
of introducing the
physical
shortest path
for the selection of best
route offering the
fast connection and greater throughput.


Introduction

In business networking the infrastructure of a
central hub type hardware device or the
software on a computer pass information
among the participants. These networks,
commonly deploy
a server to which other
workstations connect and share the resources
and information. Ad hoc networks contrary to
it do not experience such scenario of central
location type device and communications. Ad
hoc networks are banged in a sense that it is
fashio
ned among the participants and there is
no need to be connected with the internet. The
beauty of ad hoc networking is that if there is
a node who has a connection to some public or
private network, this connection can be shared
among other associates of th
e ad hoc network
which can provide a natural facility of a
connection to the internet to all of the other
users.

The main practice of ad hoc networks are
commonly for video game systems for
example data (pictures, audio and video),
Sony PSP and Nintendo DS

because
user/player make his/her work done wirelessly.
Another example of ad hoc networks may be
some departmental store's local ad hoc
network to allow their users to use new game
demos recently made available. An ad hoc
network is always peer to peer in

this wireless
era.

Keeping in account the requirements of
wireless Ad hoc networks this paper considers
minimizing duplications, quick comeback to
link breakage in active routes and forwarding
error correction by destination sequence.


Multi
-
rate traffic

and Multipath routing

Multipath routing should possess the
following properties:


1.

Dynamically route traffic

2.

Multiple paths to a destination

3.

Path taken de
pendant on the cumulative
load and child paths

4.

Help flows
to
avoid

congested links

5.

Should
be able to
balance the Load

6.

Better
response time














Time

taken for full expected backoff, RTS,
CTS,

DATA, ACK exchange. (w/ 1500 byte
payload) “Data”

is actual application level
payload, “Overhead” is everything else here
almost constant overhead regardle
ss of link
speed. Important to note that only

higher link
speed provides the shorter transmission time.

Higher link speed = shorter transmission time

Short transmission time = high ratio of MAC
overhead

per packet which gives us an idea of
how much medium
time a packet sent at each
rate consumes.

In this paper we

achieve a solution in Ad hoc

networking for the best link speed and hence
shortest transmission time.

Throughput
of an ad hoc network
depends on
numerous

factors
mainly
:


1.

Physical pattern
/arrangem
ent

of the

participant

nodes

2.

The basic

properties of
ad hoc

network

3.

communication
channel



Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


8



In this paper throughput enhancement has
been tried to achieve by adopting the shortest
physical path available as the fundamental
property of wireless ad hoc netw
orks is the
direct relationship between throughput and the
channel quality. When the distance from the
wireless source increases the channel quality
and thus the throughput gets reduce and it
ends on the breakup of the channel. There
exist tradeoff between

communication range
and the speed of the link.

MAC ada
ptively

sets

rate and multi
-
rate
allows both longer range and higher

speed
(but not at same time) also Multi
-
rate used by

most existing standards (802.11abg
HiperLANII, etc.)

and
it is more
likely to
c
ontinue into the future. Very little

research
has been made
on the effects of multi
-
rate on
ad hoc networks.


Ad hoc networking features

1.

Network
establishment time

2.

Network Depart (Time required for the ad
-
hoc network to recognize the loss of one
or more n
odes)

3.

Network reestablish

t
ime

4.

Network maximum scalability


There is modern and future requirement for
self
-
motivated ad hoc networking technology.
The rising field is of mobile and computing
with no central control, with its contemporary
focus on mobile
IP working, should be slowly
but surely expanded and it requires a highly
suitable, balance and homogenize technology
to successfully manage multi hop, ad hoc
network clusters which can perform work
separately or more than likely, be able to
communicate at

some point(s) to the already
available internet
.





Fig:
Ad hoc and fixed
Network example


Dynamic topologies:

Participants in a ad hoc network are dynamic
in a sense they are free to shift their places
without rhyme or reason; thus, the network
topolo
gy
--

which is typically multi hop

will
change unexpectedly and rapidly at irregular
in the terms of time, and will surely have both
bidirectional and unidirectional linkage.


Table
-
driven protocols

For mobile an ad hoc networking Table driven
approach is a
mong the
state of affairs

which
has been used from the beginning of such
networks. Table Driven protocol has always
the knowledge of the entire network under
consideration. Each participant of the network
maintains its routing table containing the
informat
ion of the other participants in that
network; this table is then used for sharing
data and the communication in the network.
There is always a need to ensure the updated
contents of these routing tables. For this
purpose different ways and methods have
be
en adopted. Below
are some of the

common

table
-
driven approach examples of mobile ad
hoc networks:


1)

DSDV
,
Destination

Sequence Distance
Vector routing protocol

2)

Broadcast "hello" method ___ "hello" is
broadcasted among all of the participants
in the network

and then each node be able
to update its status and routing table
entries.

3)

WRP
,

Wireless Routing Protocol

Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


9


4)

CGSR
,

Clust
er
-
head Gateway Switch
Routing

The limitation
s

of mobile infrastructure
can be
listed as:


1)

More scalability results in
producing
large
rou
ting tables

2)

Less battery power

of mobile participants

3)

Small available bandwidth

4)

High mobility of participant nodes

5)

Scalability compromises the consumption
of bandwidth

and

6)

Whenever update comes

it

definitely
produces overhead

over the network


On
-
demand ro
uting protocols

On demand routing approach is more in
practice for mobile ad hoc networking, with
this when a participant node (sender) has to
send a packet to another node (receiver) in the
network of which it has not any prior
knowledge of route then the
re will be a
calculation to discover the route. The
procedure spreads from one participant to
anther and lastly a route is configured. The
middle nodes which fall in the calculation are
to route the packets to the destination.

The participants in the netw
ork which receive
request for a route answer back to the
requester about the achievable path for the
transmission. Some of the examples of On
demand routing approaches are:


1)

AODV,
Ad
-
hoc
O
n
-
demand

Distance
Vector routing

2)

TORA,

Temporary Ordered Routing

Alg
orithm

3)

DSR, Dynamic Source Routing


The utilization of the previously discovered
route information and the storage of a network
path are the factors
as a result of

which these
approaches emerge in different functionality.


Distance Vector Routing Protocols

A
straightforward

distance

vector routing
approach

is

as follows:

1.

The first step is to maintain the list of
number of networks a router can approach
and how may hops it requires. It would
experience at
-
least two networks for which
it will assign the 1 as
a hop count.

2.

With specific interval of time the routing
table is made available for other routers
for this purpose some protocol is used to
communicate among routers. The local
updating is shared only among routers
which are physically linked by doing this

privacy is maintained and the routers of
other networks can not approach to the
new entries.

3.

At this point a fresh routing table is
created which is made from the configured
network interfaces and it also contains the
information from other routers as don
e in
the first step.

4.

The routes which result in infeasible, not
used or found bad are excluded. The
shortest path in terms of hop count is kept
and others are discarded.

5.

The fresh constructed routing table is
broadcasted to all neighbors. Hence the
informa
tion about routes is communicated
among all routers over the network and it
becomes possible for a router to maintain
the path to other networks and the
possibility of next usable router in routing
the communication to the destination.

Some distance vector

routing protocols have
been discussed here they use hop count as the
distance factor.

Routing Information Protocol V1 & V2
:


The very simple distance vector approach is
RIP V1 which uses static metric for the route
comparison. The working of RIP V1 has be
en
improved by introducing Split Horizon and
Poison Reverse which has increased its
performance in the complex networks. In the
first version of RIP hope count if exceeds 15
the route is then not maintained. In RIP V2
some additions have been introduced wh
ich
include e
xternal route label
s
, Subnet masks,
Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


10


neighbor hop router addresses and

a
uthentication
.


Open Shortest Path First
:

OSPF is link state routing mechanism for the
Inter
net protocol IP networks. It is
in the
category of Interior Gateway Protocols a
nd its
work is bounded in a single Autonomous
System (AS). The working of OSPF is same
as other Link State Protocols which is sending
Link State Advertisements (LSA) to the other
routers with in a single approachable area.
When the link state information
is made
informed to every other router in the network
they imply APF algorithm to calculate the
shortest path to the destination node.



Interior Gateway Routing Protocol
:


It is another distance vector routing approach.
Like other such protocols it identi
fies the routs
by some mathematical calculations of the
distance. The benchmarks for the calculations
are internet work delay, available bandwidth,
traffic load and reliability of the path. These
benchmarks can be modified and set by the
network administra
tors running the network.
The calculation of distance vector identifies
the route to follow. The routing table must be
fresh one and it is achieved by sending it all or
some portion of it as an update message to all
other neighbor routers in the network so

the
new paths if any can be used by others. IGRP
is unique in the sense that it calculates the
work by parameter list discussed above. The
IGRP also avoid loop information and offer a
path which is loop free but this is achieved
bearing increased complexi
ty. OSPF has
gathered praised over IGRP by its fast
calculation and working.




Our work

In Peer to peer WLAN ad hoc networking
scenario the throughput decreases
significantly for the all traffic directed to the
access point AP. Alternatively the overall
t
hroughput received to the participant nodes
falling in relatively small physical circular
area around AP will defiantly be greater. Thus
the conclusion of discussion is that the
throughput of multi
-
rate, multi
-
hop, peer to
peer and ad hoc network can be en
hanced by
calculating the shortest route around the AP.
The efficient route is calculated on the factor,

smaller the distance greater throughput will be
experienced.


Parameter list to be judged for the best path
evaluation:


1.

Source


2.

Destination

3.

Packet seq
uence number

4.

No of neighbor nodes

5.

Previous rout
e

6.

Best rout
e

to be used for next transmission





Fig: Best rout
e

Selection mechanism


The proposed route selection mechanism if
embedded with the existing wireless will
provide the

best results regarding throughput.



Packet sequence number

Here packet sequence number is for the
destination to rearrange it of it arrives in out of
order.


Source/new
node in the
network

Destination/
Existing
node

Packet sequence number


No of neighbor nodes


Objective distance


Best rout
e

Second
step


forward to the
best route

First
step
-

Compute

Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


11


No of neighbor nodes

Number of neighbor nodes provides the
maximum paths if the destination is n
ot
among the neighbors.


D
istance

Which is the basic parameter introduced in
this paper covering the fact that that more
close the device more will be the throughput
as discussed above in multi rate wireless
signals and their corresponding time.



Finding

b
est route

Consider the following figure which has 12
nodes in it. Let the node 1 is the source node
in the wireless ad hoc network. Apparently

the
numbers
1, 2, 3 …, 12 are indicating the node
numbers moreover this figure depicts the next
node to search
i,e. the next node after node 4
will be the node number 5.


There needs to be enough nodes between the
source and the destination to provide a faster
path.
Suggestion for the section for the best
nearest node is to follow the br
eadth first
search
BFS
as
it will minimize the
broadcasting requirements in ad hoc wireless
area network

some until

link break occurs
in
the active route. Now the basic requirement is
to reestablish the link in minimum time for
which algorithm being used c
an help. The key
point of this work is to induce a factor of
measuring the distance. It is based on the fact
that lesser the distance greater will be the
throughput.


It is to be noticed that the best next node to
connect will be the node which will have t
he
best physical distance i.e the shortest one and
after that we focus on selecting the breadth
first search which will gather out the nearest
available node fitting on the proposed scenario.

Best rout
e

Selection mechanism can be
achieved from the above sc
enario. Each new
Node will store the latest
route that is

needed
in transmission and there is no need to
remember previous paths. It minimizes
broadcasting

Which in turn reduces memory requirements

and

duplications are restricted.


Conclusion

By selecting
links which operate at the lowest
speed, the MAC protocol has no flexibility in
dealing with topological changes. This results
in paths breaking from mobility.

The proposed
work can be applied to existing link stat
e and
distance vector protocols and the BF
S along
with it will guarantee the next best node to be
chosen in the near in physical distance lying
under the presented radius of the Access point
like device.


Future work

Quick come back from the link breakage in
wireless ad hoc communication world can

be a
challenge as the existing node leaves the
active path the next active route detection may
slow down the throughput so, we plan it to be
accomplish in the next work.


References


1.

http://www.computingunplugged.com/issu
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Routing protocols for mobile ad
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hoc
networks

By Humayun Bakht


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1

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More Nodes

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Bibliography

1.

Mr. Khurram Zeeshan Haider has
completed his Masters in Computer
Science from Punjab University College of
Infor
mation Technology, Lahore.
H
e is
student of MS Software Engineering at
UET Taxila. Presently he is working as
Junior Programmer at UET Taxila. His
areas of interest are Networking, software
development and Database Management
Systems (DBMS).



2.

Mr. Qamas Gu
l Khan Safi is student of
MS Software Engineering at University of
Canadian Journal on Multimed
ia & Wireless Networks Vol. 1, No. 2 March 2010


13


Engineering & Technology Taxila. He
earned his Bachelor’s degree in Computer
Sciences from Allama Iqbal Open
University, Islamabad with distinction and
currently working as Network Supervis
or
at UET Taxila. His current areas of
interest are
Networks,
Data Mining and
Database Management Systems.


3.

Mr asim shahzad is serving as assistant
professor in department of telecom
engineering in university of engineering
and technology Taxila Pakistan a
nd also
doing his Phd in area of optical
communication. His research interest
includes optical communication and
network security. He has more than twelve
journal publication on various issues of
network security.