This document provides an overview of mobile ad-hoc networks (MANETs). It discusses how MANETs are formed without any infrastructure by mobile wireless nodes. Key points include: MANETs are useful when wired infrastructure is not present or practical; they allow for communication in disaster or battlefield situations. The document also covers routing challenges in MANETs due to dynamic topologies, and lists some common routing protocols. It discusses implementation issues like interference and discusses power constraints in MANETs. In summary, the document provides a high-level introduction to MANETs, their applications, routing challenges, and implementation considerations.

1. PRASAD ENGINEERING COLLEGE
PAPER ON
MOBILE AD-HOC NETWORK
Presented by
K.ASHWINI 096L1A0404
A.DIVYAJYOTHI 096L1A0405
III YEAR
ELECTRONICS AND COMMUNICATION ENGINEERING

2. INTRODUCTION
• Mobile wireless networks are popular in 1970s
• There are currently two variations of mobile wireless
network
• Infrastructure network
• Ad-hoc network

3. Why Ad Hoc Networks ?
• Setting up of fixed access points and backbone infrastructure is not
always viable
– Infrastructure may not be present in a disaster area or war zone
– Infrastructure may not be practical for short range radios; Bluetooth
(range ~ 10m)
•  Ad hoc networks:
– Do not need backbone infrastructure support
– Are easy to deploy
– Useful when infrastructure is absent, destroyed or impractical

4. What is an Ad hoc Network
• Collection of mobile wireless nodes forming a
network without the aid of any infrastructure
or centralized administration
• Nodes have limited transmission range
• Nodes act as a routers
5

5. WHY WE GO FOR MANET?
 The wired network is not available and multi-
hop wireless networks provide
 The only feasible means for communication and
information access
 Ex: Battlefield communications,disaster
recovery etc

6. MANET: Mobile Ad hoc Networks
A collection of wireless mobile nodes dynamically forming a
network without any existing infrastructure and the relative
position dictate communication links (dynamically changing).
From DARPA Website
7

7. Battle field communication
8

8.  May need to traverse
multiple links to reach
destination
 Mobility causes route
changes
 Circles shown the coverage
area of various laptop
computers
 Node A wants to transmit
packet to Node D,But D is not
coverage area of Node A
 It sends packet to node D via
the Node C

9. Interference in MANET
• In a wired network, every link may be
utilized simultaneously
• On the other hand, neighboring links in
an Ad-hoc network interfere with each
other
• The interference range is typically much
larger than the transmission range.

10. Implementation of backoff
• It has been observed that the
widely used exponential backoff
mechanism (e.g., IEEE 802.11)
• is unfair towards nodes in the
middle of an Ad-Hoc network
with multiple interference
domains.
• Hence the unfairness is
illustrated and the Impatient
Backoff Algorithm is proposed

11. Routing Protocols
 Proactive protocols
– Traditional distributed shortest path protocols
– Maintain routes between every host pair at all times
– Based on periodic updates; High routing overhead
– Example: DSDV (destination sequenced distance vector)
  Reactive protocols
– Determine route if and when needed
– Source initiates route discovery
– Example: DSR (dynamic source routing)
  Hybrid protocols
– Adaptive; Combination of proactive and reactive
– Example : ZRP (zone routing protocol)

12. Routing in MANET
• Routing is one of the primary function of MANET
• The development of efficient routing protocols is
nontrivial interface etc
• These routing protocol may generally be
categorized as two types
» Table-driven
» Source-initiated (demand-driven)

13. Routing in MANET
Ad-hoc Routing Protocols
Table-driven Source-initiated on-demand
DSDV WRP AODV DSR LMR ABR
TORA SSR
CGSR

14. MANET
Characteristics
 Dynamic topologies
 Limited channel bandwidth
 Variable capacity links
 Energy-constrained operation
 Limited physical security
Applications
 Military battlefield networks
 Personal Area Networks (PAN)
 Disaster and rescue operation
 Peer to peer networks
 Video gaming

15. MANET usage areas & limitations
 Military scenarios
 Sensor networks
 Rescue operations
 Students on campus
 Free internet connection sharing
 Conferences
 The coverage area of ad-hoc network is 500 square
meter

16.  Variable Bandwidth
 Disconnected Operation
 Limited Power
17

17. Power Consumption
18
Limited Power Source
Battery Lifetime is limited
Each sensor node plays a dual role of data originator
and data router (data processor)
The malfunctioning of a few nodes consumes lot of
energy (rerouting of packets and significant
topological changes)

18. Conclusion
Other interesting problems:
 Applications for MANET
 Address assignment
 Qos issues
 Improving interaction between protocol layers

19. REFERENCES
 http://ieee.ieeexplore.org/
 [1]. Rajarshi Gupta, Zhanfeng Jia, “Interference-aware QoS Routing (IQ
Routing) for Ad-Hoc Networks”, published in the proceedings of National
conference, held at Jawaharlal Nehru National College of Engineering,
Shimoga on 7-8 July 2006
 [2]. IEEE Standard for Wireless LAN Medium Access Control (MAC) and
Physical layer (PHY) Specifications, Nov. 1997. P802.11

20. 21
Any
Questions?