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International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:10 No: 02
9
A Novel Routing Algorithm for MANET
Mamoun Hussein Mamoun
Faculty of Computers and Information Sciences
Mansoura University, Egypt
[email protected]
Abstract
In this paper, we propose a novel algorithm to
routing called NRA, in mobile ad hoc networks, that
allows the network layer to adjust its routing protocol
dynamically based on SNR along the end-to-end
routing path for each transmission link. The
experimental results are very promising as the
proposed algorithm exhibits superior performance
with respect to traditional DSR routing algorithm in
terms of throughput and packet delivery ratio
Key words: MANET, QoS, Routing Protocols.
1. Introduction
A Mobile Ad hoc Network (MANET) is a dynamic
wireless network with or without fixed infrastructure.
Nodes may move freely and arrange themselves
randomly. The contacts between nodes in the network
do not occur very frequently. As a result, the network
graph is rarely, if ever, connected and message
delivery required a mechanism to deal with this
environment [1] Routing in MANET using the
shortest-path metric is not a sufficient condition to
construct high-quality paths, because minimum hop
count routing often chooses routes that have
significantly less capacity than the best paths that exist
in the network. [2]
Most of the existing MANET protocols optimize
hop count as building a route selection. Examples of
MANET protocols are Ad hoc On Demand Distance
Vector (AODV) [3], Dynamic Source Routing (DSR)
[4], and Destination Sequenced Distance Vector
(DSDV) [5]. However, the routes selected based on
hop count alone may be of bad quality since the
routing protocols do not ignore weak quality links
which are typically used to connect to remote nodes.
These links usually have poor signal-to-noise ratio
(SNR), hence higher frame error rates and lower
throughput. [6], [7].
The wireless channel quality among mobile nodes is
time varying due to fading, Doppler Effect and
pathloss. Known that the shortest-path metric does not
take into account the physical channel variations of the
wireless medium, it is desirable to choose the route
with minimum cost based on some other metrics which
are aware of the wireless nature of the underlying
physical channel. In MANET, there are many other
metrics to be considered: Power, SNR, Packet Loss,
maximum available bandwidth etc. These metrics
should come from a cross-layer approach in order to
make the routing layer aware of the local issues of the
underling layers. [8].
The ability of MANET to provide acceptable
quality of service (QoS) is restricted by the ability of
the underlying routing protocol to provide consistent
behavior despite the inherent dynamics of a mobile
computing environment. [9] [10].
Many proposals and models addressed quality of
service (QoS) among mobile nodes of the wireless
networks and considered the link quality in their
designs and architectures [11][12][13].
Our objective is to design a mechanism to provide
an efficient QoS routing protocol to enhance the
performance of existing routing protocols in Mobile ad
hoc network environment
In this paper we select DSR as one of the common
MANET protocols to demonstrate our two models,
Signal to noise Ratio (SNR), to enhance the quality of
service of the DSR. We evaluate how the protocol
differ in the methods it uses to select paths, detect
broken links, and buffer messages during periods of
link outage. Our new approach is called NRA. We
computed differences in terms of packet delivery ratio,
throughput, end-to-end latency, and mechanism
overhead. We show that the performance of DSR
protocol improved by using the proposed model.
This paper is structured as follows: Section 2
presents a DSR routing protocol. We investigate the
proposed routing protocol (NRA) in section 3. Section 4
elaborates on the simulation environment and the
International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:10 No: 02
experimental results. In Section 5, we present our
conclusion.
2. DSR Protocol
DSR is an entirely on-demand ad hoc network
routing protocol composed of two parts: Route
Discovery and Route Maintenance. In this section, we
describe the basic form of Route Discovery and Route
maintenance in DSR.
In DSR, when a node has a packet to send to some
destination and does not currently have a route to that
destination in its Route Cache, the node initiates Route
Discovery to find a route; this node is known as the
initiator of the Route Discovery, and the destination of
the packet is known as the Discovery's target. The
initiator transmits a Route Request (RREQ) packet as a
local broadcast, specifying the target and a unique
identifier from the initiator. Each node receiving the
Route Request, if it has recently seen this request
identifier from the initiator, discards the Request.
Otherwise, it appends its own node address to a list in
the Request and rebroadcasts the Request. When the
Route Request reaches its target node, the target sends a
Route Replay (RREP) back to the initiator of the
Request, including a copy of the accumulated list of
addresses from the Request. When the Replay reaches
the initiator of the Request, it caches the new route in its
Route Cache.
Route Maintenance is the mechanism by which a
node sending a packet along a specified route to some
destination detects if that route has broken, for example
because two nodes in it have moved too apart. DSR is
based on source routing: when sending a packet, the
originator lists in the header of the packet the complete
sequence of nodes through which the packet is
forwarded. Each node along the route forwards the
packet to the next hop indicated in the packet’s header,
and attempts to confirm this by means of a link-layer
acknowledgment or network layer acknowledgment. If,
after a limited number of local retransmissions of the
packet, a node in the route is unable to make this
confirmation, it returns a Route Error to the original
source of packet, identifying the link from itself to the
next node was broken. The sender then removes this
broken link from its Route Cache; for subsequent
packets to its destination, the sender may use any other
route to its destination in its Cash, or it may attempt a
new Route Discovery for that target if necessary.
3. A Proposed Routing Protocol (NRA)
10
Routing in MANET is difficult as a result of the
dynamic nature of network topology and the resource
constraints. The issue of Link reliability in mobile ad
hoc networks is a main problem to transmit messages
through the wireless channels. Routing in multi-hop
wireless networks using the shortest-path metric is not
an adequate condition to build good quality paths,
because minimum hop count routing often selects
paths that have significantly less capacity than the best
paths that exist in the network. [2]
Physical-layer limits of wireless channel because
of: time-varying fading, multipath, co-channel
interference, hostile jamming, mobility, dynamic
network topology.
In technicality, information from the transmission
links, such as Signal to Noise Ratio (SNR), can furnish
valuable information to the source node about the
transmission paths as far as routing is concerned. Each
wireless node can communicate with any other node
within its transmission range, which depends on SNR
at the receiver node.
We modified the route reply packet format and
added one extra field in the packet format to store the
worst value of SNR along the route from destination to
source.
Section 2 illustrated how original DSR works. We
modified also the mechanism of DSR process to
include our model. The new mechanism will works as
follows: When the route request packet arrives at the
destination or an intermediate node with a route to the
destination, a route reply packet will be generated.
This reply packet is then sent back to the source node
following the reverse route contained in the route
request packet. Each intermediate node will update the
SNR value if its link values of SNR lower than the
existing recorded values in the route reply packet. If
SNR value of its link is greater than recorded value,
the node will not update the value. The process will
continue until the route reply packet reach the source
node. Now, at the source node there are many of
available routes with different values of SNR. The
Source node will select the route based on the value of
best of worse available values of SNR.
4. Simulation and Results
A network simulator (NS2) [14] was developed in
order to monitor, observe and measure the
performance of MDSR routing. In simulations, we
choose propagation model based on 802.11.
The fading modules contributed in [15] are included
into account. The modulation, BPSK, compute the
BER under fading condition from the loop-up tables.
We calculate the Doppler shift velocity according to
International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:10 No: 02
Table1. Configuration parameters
Configuration Parameter
Value
Effective comm. area
300- 400 m
Terrain range
3000x3000 m
No. of nodes
80
Modulation Scheme
BPSK
Threshold Power
-75dBm
Propagation Pass Loss
Free space
Fading model
Rician
Rician Fading factor
5
Speed
3-12 m/sec
Packet size
1024 bits
Routing protocol
NRA, DSR
MAC layer
IEEE 802.11
Routing protocol
DSR and MDSR
Carrier frequency
2.4 GHz
90
P a c k e t d e l i v e ry (p a c k e t/ s e c )
the ground speed, pitch, and yaw of the transmitting
node and the receiving node. Look up the fading
amplitude according to the Rician K=5 factor [16].
We considered in our network topology to include
fading, Doppler Effect and various speed mobility.
Under these simulation conditions, the wireless
node is configured as:
11
80
70
60
50
NRA
40
DSR
30
20
10
0
0
50
100
150
200
250
300
350
Pause time (sec)
Figure2. Packet delivery vs. Pause time
From figure 1, it is noticed that there is an increase
in the network throughput due to the using of the NRA
protocol compared to the traditional DSR showing that
the influence of our algorithm to the DSR protocol.
From figure 2, it is noticed that there is an increase
in the packet delivery ratio due to the using NRA
compared to the standard DSR protocol showing that
the influence of the our algorithm to the DSR protocol.
45
18000
Throughput (bit/sec)
16000
14000
E n d -to -e n d d e l a y (s e c )
40
The results of experiments are shown in the
following Figures.
35
30
25
NRA
20
DSR
15
10
5
12000
0
NRA
10000
0
50
DSR
100
150
200
250
300
350
Pause time (sec)
8000
6000
4000
Figure3. End-to-end delay vs. Pause time
2000
0
Pause tims (sec)
Figure1. Throughput vs. Pause time
From figure 3, it is noticed that there is slightly
increase in End-to-End delay in NRA compared to
traditional DSR.
5. Conclusion
In this paper, we propose a new algorithm to
modify the DSR routing protocol to choose routes
according to the Signal to Noise Ratio (SNR) criterion
which is characterized with the best value of SNR of
the weakest link along the route from destination to
source to eliminate the routes with bad links that has
very low SNR and to improve QoS.
Simulation results show that our model achieved
better performance than traditional DSR protocol in
International Journal of Electrical & Computer Sciences IJECS-IJENS Vol:10 No: 02
terms of delivery rate and throughput over intermittent
network.
6. References
[1] F. Alnajjar, T. Saadawi, “Social-stratification
Probabilistic Routing Algorithm in Delay-Tolerant
Networks”, The International Conference on Wireless
Algorithms, Systems and Applications (WASA'09), Boston,
MA, pp. 579–59, August 2009.
[2] W. Ho Yuen, H. Lee and T. D. Andersen “A Simple and
Effective Cross Layer Networking System for Mobile Ad
Hoc Networks”, PIMRC 2002, vol. 4, pp. 1952-1956,
September 2002.
[3] C. E. Perkins and E. M. Royer, “Ad-hoc on-demand
distance vector routing”, Proc. IEEE Workshop on Mobile
Comp. Systems .and Applications, pp. 90-100, Feb. 1999.
[4] D. B. Johnson and D. A. Maltz, “Dynamic source routing
in ad hoc wireless networks”, Mobile Computing, pp. 153181, 1996.
[5] C. E. Perkins and P. Bhagwat, “Highly dynamic
destination sequenced distance-vector routing (DSDV) for
mobile computers”, Computer Communications Review, pp.
234-244, Oct.1994.
[6] H. M. Tsai, N. Wisitpongphan and O.K. Tonguz,
“Link-Quality Aware AODV Protocol,” Proc. IEEE
International Symposium on Wireless Pervasive Computing
(ISWPC), Phuket, Thailand, January 2006
[7] E. Royer and C.-K. Toh, "A Review of Current Routing
Protocols for Ad Hoc Mobile Wireless Networks", IEEE
Personal Communications Magazine, vol. 6, No. 2, April
1999.
[8] M. Drini and T. Saadawi, “Modeling Wireless Channel
for Ad-Hoc Network Routing Protocol”, ISCC Marakech
Marocco, pp. 549-555, July 2008.
[9] J. Novatnack , L. Greenwald and H. Arora, “Evaluating
ad hoc routing protocols with respect to quality of service”,
Wireless And Mobile Computing, Networking And
Communications, Vol. 3, pp. 205-212, Aug. 2005.
[10] F. Aune, “Cross-Layer Tutorial”, NTNU 2004.
[11] N. Wisitpongphan, G. Ferrari, S. Panichpapiboon, J.S.
Parikh and O.K. Tonguz, "QoS provisioning using BERbased routing for ad hoc wireless networks", IEEE Vehicular
Tech. Conf. (VTC), pp. 2483-2487, Spring 2005.
[12] B. R Arun kumar, C. Lokanatha Reddy and P. S.
Hiremath, “High performance Modified DSR with Power
Consumption Optimization for Mobile Ad hoc Networks”,
IJCSNS International Journal of Computer Science and
Network Security, Vol.7, No. 5, May 2007.
12
[13] V. Gulati, A. Garg and N. Vaidya, “Anycast in Mobile
Ad Hoc Networks”, Technical Report, Texas A&M
University, April 2001.
[14] D. Cavin, Y. Sasson and A. Schiper, “On the accuracy
of MANET simulators”, Proceeding ACM POMC’02, pp.
38-43, Oct. 2002.
[15] R. J. Punnoose, P. V. Nikitin, and D. D. Stancil,
“Efficient simulation of Rician fading within a packet
simulator”, September 2000. Code available at
http://www.ece.cmu.edu/downloads/ns2 ricean dist.tgz
[16]. Theodore Rappaport, Wireless Communications:
Principles and Practice, Prentice Hall PTR, Upper Saddle
River, NJ, 2001.
Bibliography
▲Name:
Dr. Mamoun
Hussein Mamoun.
Address: Faculty of
Computer and Information
Sciences,
Mansoura
University, Egypt.
Education & Work
experience: has completed B.S. degree in electrical
and computer engineering from Military Technical
Collage (Egypt) in June 1979, his M.S degree in
electrical and computer engineering from Cairo
University (Faculty of Engineering) in Oct. 1985 and
PhD degree in electrical and computer engineering
from Cairo University (Faculty of Engineering) in
Dec.1990.His research interests including Routing and
Multicast for MANET. Presently he is working as
Associate Prof. in Faculty of Computers and
Information Sciences, Mansoura University, Egypt.
Tel: +20180554768
: +966594113095
E-mail: [email protected]
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