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Ad hoc networks introduction
- 1. 1 An Introduction to Mobile Ad hoc Network and Its Research Issues Dr. Noman Islam Email: noman.islam@indus.edu.pk Web: https://sites.google.com/a/nu.edu.pk/noman-islam/ http://facebook.com/sir.noman.islam
- 2. What is Ad hoc Network? 2 According to Webster's online dictionary, the term Ad hoc stands for any thing that is improvised or for a specific purpose etc. Ad hoc Networks are: infrastructure-less networks erected on-the-fly among a set of nodes for a specific purpose
- 3. Types of Ad hoc Networks 3 Wireless Sensor Network Mobile Ad hoc Network Wireless Mesh Network
- 4. Mobile Ad hoc Network (MANET) 4 □ IETF defines MANET as follows: “MANET is an autonomous system of mobile routers (and associated hosts) connected by wireless links--the union of which form an arbitrary graph. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet”
- 5. Properties of MANET 5 Properties Conventional Network MANET Nodes Mobility – + Resource + – Reliability + – Links Bandwidth + – Symmetry + – Stability + – Environment Dynamism – + Infrastructure + – Certification Authority + – DHCP + – Interoperability + – Nodes Acquaintance + –
- 6. Why MANET? 6 The zero dependence on infrastructure and swift and facile deployment of MANET can foster a numberof useful applications like ubiquitous computing, disaster recovery etc.
- 7. 7 Military Application Ubiquitous Computing Disaster Recovery Vehicular Ad hoc Network Applications of Mobile and Ad hoc Networks
- 8. Ad hoc Gaming Smart Agriculture Animal Monitoring Applications of Mobile and Ad hoc Networks
- 10. Research Issues in MANET 10 Conventional networking protocols fails to perform when employed on MANET due to its exclusive temperament like: Dynamic topology Frequent network partitioning Multihop routing Resource constraints Volatile links No dedicated entities
- 11. Research Trends in MANET 11 Research trends for various issues (grouped in 15 categories) over the six year (1998 to 2003), a survey of more than 1300 MANET related papers
- 12. Research Trends in MANET 12 Research trends for various MANET issues in 2003
- 13. Selected Research Issues 13 Power Management MAC Layer Protocol Routing Addressing Transport Protocols Security Mobility Models Standardization Challenge Data Management
- 14. Power Management 14 The nodes in MANET have poor resources Algorithms should keep into account the power consumption in different modes of operation i.e. Sleep / Standby Mode Doze Active Coordinated effort at all layers Adjusting the transmission power to optimal value Energy efficient routing
- 15. MAC Layer 15 Distributed or Centralized Hidden Vs Exposed Node problem Minimum Control Overhead Bandwidth reservation made at one point of time may become invalid once the node moves out of the region Contention Free Vs Contention based TDMA, FDMA, CDMA CSMA that senses the spectrum first MACA that transmits RTS / CTS packets Hidden Node Problem Exposed Node Problem
- 16. Routing 16 Challenges like: Frequent route changes Routing loops Scalability Routing Protocols Flat Protocols Proactive DSDV CSGR, WRP Reactive AODV DSR TORA Hybrid ZRP Position Based Routing GPSR DREAM
- 18. Other types of routing protocols 18 QoS aware routing Energy efficient routing Secure routing Multicast routing Tree based Mesh based
- 19. Addressing Issue 19 No DHCP, no pre assignment of addresses Generate tentative address (e.g. using hashing algorithms) and check for uniqueness What happens with: Network partitioning Network merger Mobile IP can address some of the issues Security is also an important issue DOS attack Election of DHCP server Statefull and Stateless approaches
- 20. Transport protocol 20 Transport Protocols TCP : connection oriented, reliable, flow control, congestion control UDP : unreliable, low overhead, connection less TCP Congestion Control Additive Increase Multiplicative Decrease designed for fixed networks packet loss as an indication of congestion packet loss is a common phenomena in MANET due to mobility packet loss leads to congestion control algorithm. that leads to reduction in window size and hence degrades performance Cross-layer communication can be exploited
- 22. Security Issue 22 Lack of Secure Boundaries (specially in battlefield environments) Threats from Compromised nodes Inside the Network Byzantine failures Lack of Centralized Management Restricted Power supply DOS attack Scalability
- 23. Security issue 23 Physical layer Signal jamming Routing layer attacks Multipath routing
- 24. Security Attacks at various layers 24
- 25. Mobility Models 25 Random Walk Mobility Model City Section Mobility ModelRandom Direction Mobility Model Random Waypoint Mobility Model
- 26. Standardization Issue 26 IETF MANET working group working on routing protocols IEEE 802.15 group For personal area networks (PAN) IEEE 802.11p Family of Standards for Wireless Access in Vehicular Environments (WAVE)
- 27. Cooperation Issue 27 Interdependency Requires cooperation Presence of selfish nodes even in small number can jeopardize network Two schemes: Cooperation enforcement Incentive based mechanism
- 28. Data Management Issue 28 PROBLEM ISSUES / SOLUTIONS Routing Reactive or Proactive Routing Protocols Service Discovery Centralized or Distributed directory Location Management Global Positioning System Query Processing and Optimization Profile Driven Querying, Optimization, Location Based Querying Caching Profile Driven, Cooperative, Semantic caching Replication Partial or Full Replication Naming Flooding or Name Server Transaction Management Can we satisfy all ACID requirements? Hetrogeneity Transcoding techniques Security DOS Attacks, Trust Issues
- 29. Conclusion 29 A basic introduction to MANET and its research issues have been highlighted Most of the protocols of MANET are still at infancy stage A number of avenues are available for research in the area of MANET
Editor's Notes
- 1. Greedy Perimeter Stateless Routing for Wireless Networks (GPSR) 2. Distance Routing Effect Algorithm for Mobility (DREAM)
- Wormhole attack: An attacker records packets at one location in the network and tunnels them to another location. Routing can be disrupted when routing control messages are tunneled. This tunnel between two colluding attackers is referred as a wormhole [8] [32]. Wormhole attacks are severe threats to MANET routing protocols. For example, when a wormhole attack is used against an on-demand routing protocol such as DSR or AODV, the attack could prevent the discovery of any routes other than through the wormhole. ² Blackhole attack: The blackhole attack has two properties. First, the node exploits the mobile ad hoc routing protocol, such as AODV, to advertise itself as having a valid route to a destination node, even though the route is spurious, with the intention of intercepting packets. Second, the attacker consumes the intercepted packets without any forwarding. However, the attacker runs the risk that neighboring nodes will monitor and expose the ongoing attacks. There is a more subtle form of these attacks when an attacker selectively forwards packets. An attacker suppresses or modifies packets originating from some nodes, while leaving the data from the other nodes unaffected, which limits the suspicion of its wrongdoing. ² Byzantine attack: A compromised intermediate node works alone, or a set of compromised intermediate nodes works in collusion and carry out attacks such as creating routing loops, forwarding packets through non-optimal paths, or selectively dropping packets, which results in disruption or degradation of the routing services [17].
- In Random way point, An MN begins by staying in one location for a certain period of time (i.e., a pause time). Once this time expires, the MN chooses a random destination as well as a speed. It then travels towards the newly chosen destination at the selected speed. Upon arrival, the MN takes another break before starting the process again. In the Random Walk Mobility Model, a host moves from its current location to a new location by randomly choosing a direction and speed in which to travel In this Random direction model , MNs choose a random direction in which to travel instead of a random destination. After choosing a random direction, an MN travels to the border of the simulation area in that direction. As soon as the boundary is reached the MN stops for a certain period of time, chooses another angular direction (between 0 and 180 degrees) and continues the process. In the City Mobility Model, the simulation area is a network that represents the section of a city where the ad hoc network exists. Each mobile nodes begins the simulation at a defined point of some street. The movement algorithm from the current destination to the new destination locates a path corresponding to the shortest travel time between the two points; in addition, there are safe driving characteristics such as a speed limit and a minimum distance allowed between any to mobile nodes. While reaching the destination, the Mobile Node pauses for a specific time and then randomly chooses another destination (i.e., a point of some street) and repeats the process.