The document proposes a Neighbor Coverage based Probabilistic Rebroadcast (NCPR) protocol to reduce routing overhead in mobile ad-hoc networks. NCPR uses two parameters - connectivity factor and additional coverage ratio - to calculate a rebroadcast probability. It modifies the AODV routing protocol by adding a "num_neighbors" field to the RREQ packet header to reduce overhead from broadcasting neighbor lists. Simulation results show that NCPR achieves lower routing overhead compared to simple flooding. Future work could explore implementing NCPR with variable bit rate traffic instead of constant bit rate.

1. A NEIGHBOR COVERAGE BASED
PROBABILISTIC REBROADCAST FOR
REDUCING ROUTING OVERHEAD IN
MOBILE AD-HOC NETWORK
ABHIRAM.S
ROLL NO :20181
MTECH COMM. ENGG

2. Add-Hoc Network
• It is a decentralized type of wireless network.
• It does not rely on a pre-existing infrastructure, such as routers in wired
networks or access points in wireless networks.
• The routing decisions are made by the node itself.
• Ad-hoc network can be broadly classified into MANET and VANET.

3. MANET
• mobile ad hoc network (MANET) is a self-routing network of mobile
devices connected wirelessly
• MANETs have many applications : such as
military communication,
in search and rescue operations,
in home and enterprise networks,
in entertainment,
and in sensor networks

4. ROUTING PROTOCOLS IN MANET
• There are number of routing protocols in manet such as AODV,DSDV,DSR
etc..
• The routing protocols in MANET is classified into four types
1) PROACTIVE ROUTING
2) REACTIVE ROUTING
3) HYBRID ROUTING
4) HIERARCHICAL ROUTING

5. REACTIVE ROUTING
• This protocol do not have any pre determined routing table, it is otherwise
called On Demand Routing Protocol
• Here node initiates a route discovery process throughout the network, only
when it wants to send packets to its destination.
• Route discovery is done by using flooding of route request packets
• Eg: AODV

6. BROADCASTING
• Broadcasting is the simplest way for route discovery
• Broadcasting protocols are classified into 4 types
1)Simple flooding
2)Probability based method
3)Area based method
4)Neighbor knowledge method
• Performance of
neighbor knowledge based method>area based method>probability based method

7. A NEIGHBOR COVERAGE BASED
PROBABILISTIC REBROADCAST(NCPR)
• NCPR is used to reduce routing overhead in mobile ad-hoc network.
• Here we use two parameter to obtain ‘rebroadcast probability’; they are
connectivity factor and additional coverage ratio.
• Additional coverage ratio=No. of nodes covered in a single broadcast/Total
number of neighbors
• Connectivity Factor: It gives the relationship of network connectivity &
number of neighbors of a given node

8. PROTOCOL IMPLEMENTATION
• Proposed NCPR requires hello packets to obtain neighbor information.
• Here we use some technique to reduce the routing overhead of hello packets.
1) We don't use periodic hello mechanism. The hello messages are send by
nodes if and only if
time elapsed from last broadcasting packet> hello interval
2)in order to reduce the overhead of neighbor list in the RREQ packet, each
node monitor the variation in neighbor table and maintain a cache of
neighbor list

9. • We modify the RREQ header of AODV and a fixed field “num_neighbors”
and this field is followed by dynamic neighbor list.
• If neighbor table of ‘ni’ adds at least one neighbor ‘nj’; then node ‘ni’ set the
num_neighbor to the number of listed neighbors plus a +ve integer.
• If neighbor table of ‘ni’ deletes some neighbors then the node ‘ni’ set the
num_neighbors to a –ve integer, which is equal and opposite to number of
deleted nodes
• If neighbor table of ‘ni’ does not vary then num_neigbors set to zero & ‘ni’
does not need to list its neighbors.

10. • LIST OF FILES THAT NEED TO BE MODIFIED
• ~/ns-allinone-2.35/ns-2.35/common/packet.h
• ~/ns-allinone-2.35/ns-2.35/trace/cmu-trace.h
• ~/ns-allinone-2.35/ns-2.35/trace/cmu-trace.cc
• ~/ns-allinone-2.35/ns-2.35/tcl/lib/ns-packet.tcl
• ~/ns-allinone-2.35/ns-2.35/tcl/lib/ns-default.tcl
• ~/ns-allinone-2.35/ns-2.35/tcl/lib/ns-lib.tcl
• ~/ns-allinone-2.35/ns-2.35/queue/priqueue.cc

11. SIMULATION TOOL AND PARAMETERS
• The simulation is done by using NETWORK SIMULATOR-2 (NS 2)
• The parameters of the scenario is given in the table shown below.
Parameter value
Simulator NS
Version 2.35
Protocol studied NCPR
Number of nodes 30 and 50
Simulation Time 60 sec
Simulation Area 2000x2000
Traffic Type UDP
Data Payload Bytes/packet
Bandwidth 600kbps

12. SIMULATION RESULTS

13. FUTURE WORKS
• Constant bit rate (CBR) NCPR protocol can be changed to variable bit rate
(VBR), in order to get better
1)Throughput
2)end to end delay
3)packet delivery ratio

14. REFERENCES
• Performance Analysis of MANET Routing Protocols Using An Elegant Visual Simulation Tool
Nazmus Saquib1, Md. Sabbir Rahman Sakib, and Al-Sakib Khan Pathan2Department of Electrical and Electronic
Engineering, BRAC University Department of Computer Science and Engineering, BRAC University66 Mohakhali, Dhaka
1212, Bangladesh{nsaquib, srsakib}@bracu.ac.bd, sakib.pathan@gmail.com
• Simulation and Evaluation of MANET Routing Protocols for Educational Purposes
Alexandros Kaponias, Anastasios Politis, and Constantinos Hilas, Department of Informatics and Communications T.E.I. of
Serres Serres, Greece pli1542@teiser.gr. anpol@teiser.gr, chilas@teiser.gr
• Performance analysis of AODV, DSR & TORA Routing Protocols
Anuj K. Gupta, Member, IACSIT, Dr. Harsh Sadawarti, Dr. Anil K. Verma
• A comprehensive overview about selected Ad-Hoc Networking Routing Protocols
Daniel Lang March 14, 2003

15. THANK YOU