MOBILE AD HOC NETWORK

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OUTLINE-

• INTRODUCTION TO MANET
• HISTORY OF MANET
• ROUTING PROTOCOLS
• REACTIVE PROTOCOL
• PROACTIVE PROTOCOL
• HYBRID PROTOCOL
• PROBLEMS OF MANET
• SECURE DATA TRANSMISSION IN MANET
• APPLICATIONS OF MANET
• CONCLUSION

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INTRODUCTION TO MANET-

• A mobile ad-hoc network is a collection of
  mobile nodes forming an ad-hoc network without
  the assistance of any centralized structures.
  These networks introduced a new art of network
  establishment and can be well suited for an
  environment where either the infrastructure is
  lost or where deploy an infrastructure is not
  very cost effective.
• There are quite a number of uses for mobile
  ad-hoc networks which can be discussed later .

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HISTORY OF MANET

• The whole life-cycle of ad-hoc networks could be
  categorized into the first, second, and the third
  generation ad-hoc networks systems.
• FIRST GENERATION-
• The first generation
  goes back to 1972. At the time, they were called
  PRNET (Packet Radio Networks). In conjunction
  with ALOHA (Areal Locations of Hazardous
  Atmospheres) and CSMA (Carrier Sense Medium
  Access), approaches for medium access control and
  a kind of distance-vector routing PRNET were used
  on a trial basis to provide different networking
  capabilities in a combat environment.

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SECOND GENERATION

• The second generation of ad-hoc networks emerged
  in 1980s,when the ad-hoc network systems were
  further enhanced and implemented as a part of the
  SURAN (Survivable Adaptive Radio Networks)
  program. This provided a packet-switched network
  to the mobile battlefield in an environment
  without infrastructure. This program proved to be
  beneficial in improving the radios' performance
  by making them smaller, cheaper, and resilient to
  electronic attacks.
• In the 1990s, the concept of commercial ad-hoc
  networks arrived with notebook computers and
  other viable communications equipment. At the
  same time, the idea of a collection of mobile
  nodes was proposed at several research
  conferences. The IEEE 802.11 subcommittee had
  adopted the term "ad-hoc networks" and the
  research community had started to look into the
  possibility of deploying ad-hoc networks in other
  areas of application.
• Meanwhile, work was going on to advance the
  previously built ad-hoc networks. GloMo (Global
  Mobile Information Systems) and the NTDR
  (Near-term Digital Radio) are some of the results
  of these efforts.

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THIRD GENERATION

• Present ad-hoc networks systems are considered as
  the third generation.

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ROUTING PROTOCOL OF MANETs
Mobile ad hoc networks routing protocols are
characteristically subdivided into three main
categories. These are proactive routing
protocols, reactive routing protocols and hybrid
routing protocols.
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• The Efficient routing protocols can provide
  significant benefits to mobile ad hoc networks,
  in terms of both performance and reliability.
• Reactive Routing Protocols
  Reactive MANET protocols only find a route to the
  destination node when there is a need to send
  data. The source node will start by transmitting
  route requests throughout the network. The sender
  will then wait for the destination node or an
  intermediate node (that has a route to the
  destination) to respond with a list of
  intermediate nodes between the source and
  destination. This is known as the global flood
  search, which in turn brings about a significant
  delay before the packet can be transmitted. It
  also requires the transmission of a significant
  amount of control traffic. Thus,
  reactive MANET protocols are most suited for
  networks with high node mobility or where the
  nodes transmit data infrequently.

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FOLLWING ARE THE REACTIVE PROTOCOLS

• AD HOC ON DEMAND DISTANCE VESTOR(AODV)
• DYNAMIC SOURCE ROUTING(DSR)
• ADMISSION CONTROL ENABLED ON DEMAND
  ROUTING(ACOR)
• ASSOCIATIVITY BASED ROUTING(ABR)

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PROACTIVE ROUTING PROTOCOLS

• Proactive MANET protocols are table-driven and
  will actively determine the layout of the
  network. Through a regular exchange of network
  topology packets between the nodes of the
  network, a complete picture of the network is
  maintained at every single node. There is hence
  minimal delay in determining the route to be
  taken. This is especially important for
  time-critical traffic .
• However, a drawback to a proactive MANET of
  protocol is that the life span of a link is
  significantly short. This phenomenon is brought
  about by the increased mobility of the nodes,
  which will render the routing information in the
  table invalid quickly.
  
  
  
  Thus, proactive MANET protocols work
  best in networks that have low node mobility or
  where the nodes transmit data frequently.

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FOLLWING ARE THE PROACTIVE ROUTING PROTOCOLS

• DESTINATION SEQUENCED DISTANCE VECTOR(DSDV)
• OPTIMISED LINK STATE ROUTING(OLSR)
• WIRELESS ROUTING PROTOCOL(WRP)
• CLUSTER HEAD GATE WAY SWITCH ROUTING(CGSR)

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HYBRID ROUTING PROTOCOL

• Since proactive and reactive routing protocols
  each work best in oppositely different scenarios,
  there is good reason to develop hybrid routing
  protocols, which use a mix of both proactive and
  reactive routing protocols. These hybrid
  protocols can be used to find a balance between
  the proactive and reactive protocols.
  The basic idea behind hybrid routing
  protocols is to use proactive routing mechanisms
  in some areas of the network at certain times and
  reactive routing for the rest of the network. The
  proactive operations are restricted to a small
  domain in order to reduce the control overheads
  and delays. The reactive routing protocols are
  used for locating nodes outside this domain, as
  this is more bandwidth-efficient in a constantly
  changing network.

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FOLLOWING ARE THE HYBRID ROUTING PROTOCOLS

• TEMPORARY ORDERED ROUTING ALOGORITHM(TORA)
• ZONE ROUTING PROTOCOL(ZRP)
• ORDERONE ROUTING PROTOCOL(OORP)

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PROBLEMS OF MANET

• The first, and the most important scenario, is
  the ability to establish a network in places
  where it's not possible otherwise i.e., in a
  disaster relief setting, or in a situation where
  the entire communication structure has been
  destroyed.
• One thing we should be clear about is, there's
  no doubt two machines in an ad-hoc network could
  be networked, but with a completely different art
  of network formation. No router, no
  administrator, no access server, etc. What does
  it mean? It means we can't use the existing
  strategies for network control as efficiently as
  we do in a fixed wireless network. New technology
  requires new techniques. This is one of the major
  issues that appears to be an obstacle in
  deploying an ad-hoc network as a leading
  technology in the future wireless generation.

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• Routing, security, limited bandwidth, and low
  power are some of the important challenges to the
  technology.
• As far as low power is concerned, it's more of a
  hardware issue. However, it does effect the other
  operations of the ad-hoc network.
• Consider that in a network there are three
  nodes named as node1,node2,node3. Assume that
  the node1 wants to transmits data to the node3
  through node2(router) .If node2 refuses to
  transmit the data or unable to do so then this
  leads to a problem.

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SECURE DATA TRANSMISSION IN MANET

• In mobile ad-hoc networks, a mobile node meets
  two types of security challenges import and
  export authorization.
• Import authorization requires a node acting as a
  router to decide weather or not it should modify
  its routing information when it receives
  information from somewhere outside.
• Export authorization requires the router to make
  a decision whenever it receives a request for
  routing information.
• Source authentication we need to be able to
  verify that the node is the one it claims to be.
• Integrity we need to be able to verify that the
  routing information that it is being sent to us
  has arrived safely.

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• From the security perspective, in mobile ad-hoc
  networks there are two kinds of messages--the
  routing, and the data message--with different
  natures and different security needs.
• Data messages are point-to-point and can
  therefore be saved by using an existing
  point-to-point security mechanism, such as IPSec
  (Secure Internet Protocol).
• However, for routing messages, there will always
  be some parts of those messages that will change
  during their propagation. This is perhaps the
  main challenge posed by routing messages to the
  ad-hoc environment.
• Normally, routing messages carry two types of
  information, mutable and non-mutable. It's
  desirable that the mutable information in a
  routing messages is secured in such a way that no
  trust in intermediate nodes is required.
  Otherwise, securing the mutable information will
  be much more computationally intensive. Plus, the
  overall security of the system will greatly
  decrease.

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• One possible solution is to use a trusted
  certificate server C, whose public key is known
  to all participating nodes.
• Keys are priority generated and are exchanged
  through a mutual relationship between C and each
  node. Each node obtains a certificate with
  exactly a single key from the trusted certificate
  server upon joining the network.
• The certificate details different aspects of the
  connecting node. These details include node
  addresses, a public key, and a time stamp t1 and
  t2, where t1 and t2 represent the certificate
  issue and certificate expiration time. These
  certificates are authenticated and signed by the
  server C.

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• The goal of communication between the source and
  the destination is to make sure that the data
  safely reaches the destination.
• Therefore, whenever a node wants to transmit data
  to a destination for which it does not have any
  routing entry in its routing tables, it can adopt
  one of several mechanisms, such as invoking a
  route discovery mechanism (on-demand protocols),
  or invoking route discovery and data delivery
  processes (mobile ad-hoc on-demand data delivery
  protocol). As for the security perspective,
  besides an IP address of the destination, a
  broadcast ID, and a source ID, the packet also
  contains a certificate A and the expiration
  time t2. All of these are assigned to the public
  key, which was allocated to the source node at
  the time it joined.
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• Each intermediate or receiving node of the
  package extracts the public key from the
  certificate C attached to the packet to validate
  the signature and make sure the certificate is
  still valid before forwarding it to other nodes.
• To explain further, consider a scenario in
  which node A wants to transmit data to node D.
  Node B on the receiving route request verifies
  the public key and the certificate validation
  time by extracting this information from the
  certificate attached to the packet. Once this has
  been done, B then removes the A certificate
  signature, records B as predecessor, signs the
  contents of the message originally broadcast by
  A, appends its own certificate, and forwards the
  broadcast message to the neighboring node until
  it reaches D.

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APPLICATIONS OF MANET

• One of many possible uses of mobile ad-hoc
  networks is in some business environments, where
  the need for collaborative computing might be
  more important outside the office environment
  than inside, such as in a business meeting
  outside the office to brief clients on a given
  assignment.
• A mobile ad-hoc network can also be used to
  provide crisis management services applications,
  such as in disaster recovery, where the entire
  communication infrastructure is destroyed and
  resorting communication quickly is crucial. By
  using a mobile ad-hoc network, an infrastructure
  could be set up in hours instead of weeks, as is
  required in the case of wired line communication.

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• Another application example of a mobile ad-hoc
  network is Bluetooth, which is designed to
  support a personal area network by eliminating
  the need of wires between various devices, such
  as printers and personal digital assistants.

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CONCLUSION

• We have presented a detailed performance
  comparison of routing protocols for mobile ad hoc
  wireless networks. Reactive protocols performed
  well in high mobility scenarios than proactive
  protocol. High mobility result in highly dynamic
  topology i.e. frequent route failures and
  changes. Both proactive protocols fail to respond
  fast enough to changing topology.
• Security is one of the fundamental issues in
  mobile ad-hoc networks. I've highlighted
  different security requirements, along with a
  possible solution to secure transmission in these
  types of networks. The proposed security solution
  is one of several ways to protect data
  communication in mobile ad-hoc networks.
• However, there's a solid need to deploy
  more efficient strategies to resolve various
  issues besides security in mobile ad-hoc
  networks.

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