Wireless and mobile computing in Computer science.pptx

Wireless and mobile computing in Computer science.pptx

1. Wireless and Mobile Computing By Hannan Bin Liaqat Department of CS& IT University of Gujrat

2. Lecture Agenda Mobile Ad hoc Networks (MANETs): Overview Properties of a MANET Need of MANET Architecture Standards and Application Challenges and Issues

3. Mobile Ad hoc Networks (MANETs): Definition: A mobile ad hoc network ( MANET ), is a self-configuring infrastructure less network of mobile devices connected by wireless links. autonomous network stub network

4. 4 Fundamental Concepts Ad hoc networks are autonomous networks operating either in isolation or as “stub networks” connecting to a fixed network Do not necessarily rely on existing infrastructure No “access point” Each node serves as a router and forwards packets for other nodes in the network Topology of the network continuously changes

5. 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

6. Mobile Ad Hoc Networking (MANET) Characteristics: No backbone infrastructure dynamic topologies: nodes are free to move arbitrarily bandwidth-constrained, variable capacity links energy-constrained operation Nodes with limited battery life and storage capabilities limited physical security may have both unicast and multicast/broadcast traffic

7. 7 Motivation Battlefield survivability Must support mobility Avoid single point of failure typical of centralized systems Often unable to rely on existing communications infrastructure Desire for a rapidly deployable, self-organizing network Multi-hop packet routing used to exchange messages between users who are not within LOS of each other

8. 8 Applications Military Rapidly deployable battle-site networks Sensor fields remote-controlled aerial vehicles Disaster management Disaster relief teams that cannot rely on existing infrastructure Neighborhood area networks (NANs) Shareable Internet access in high density urban settings

9. 9 Applications Impromptu communications among groups of people Meetings/conferences sports stadiums boats, small aircraft Automobile communications Personal area networking cell phone, laptop, ear phone, wrist watch Emergency operations search-and-rescue policing and fire fighting

10. 10 Standardization Internet Engineering Task Force (IETF) MANET working group ( http://www.ietf.org/html.charters/manet-charter.html ) “The primary focus of the working group is to develop and evolve MANET routing specification(s) and introduce them to the Internet Standards track. The goal is to support networks scaling up to hundreds of routers. (…) The working group will also serve as a meeting place and forum for those developing and experimenting with MANET approaches.”

11. 11 A Typical MANET Overlap of Transmission Ranges of Nodes allows Packet Forwarding Packets travel over multiple wireless hops A B A B

12. Multi-Hop Wireless May need to traverse multiple links to reach destination Mobility causes route changes

13. Challenges in Mobile Environments Limitations of the Wireless Network packet loss due to transmission errors variable capacity links frequent disconnections/partitions limited communication bandwidth Broadcast nature of the communications Limitations Imposed by Mobility dynamically changing topologies/routes lack of mobility awareness by system/applications Limitations of the Mobile Computer short battery lifetime limited capacities

14. Effect of mobility on the protocol stack Application new applications and adaptations Transport congestion and flow control Network addressing and routing Link media access and handoff Physical transmission errors and interference