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Mobile Computing COE 446 Mobile Ad hoc Networks

Mobile Computing COE 446 Mobile Ad hoc Networks. Tarek Sheltami KFUPM CCSE COE http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm. Many Applications. Personal area networking cell phone, laptop, ear phone, wrist watch Military environments soldiers, tanks, planes Civilian environments

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Mobile Computing COE 446 Mobile Ad hoc Networks

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  1. Mobile Computing COE 446Mobile Ad hoc Networks Tarek Sheltami KFUPM CCSE COE http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm

  2. Many Applications • Personal area networking • cell phone, laptop, ear phone, wrist watch • Military environments • soldiers, tanks, planes • Civilian environments • taxi cab network • meeting rooms • sports stadiums • boats, small aircraft • Emergency operations • search-and-rescue • policing and fire fighting

  3. Why Ad hoc Networks? • No infrastructure needed (no routing in fixed wireless) • Can be deployed quickly, where there is no wireless communication infrastructure present • Can act as an extension to existing networks  enhances coverage • Cost-effective – cellular spectrum costs $XX billion • Adaptive computing and self-configuring • Support for heterogeneous computational devices and OSs

  4. Ad hoc Constraints • Dynamic topologies • Bandwidth-constrained • Constraints on Tx power • Infrastructure-less property, no central coordinators  hidden terminal, exposed terminal • No QoS preservation • Load balancing • Energy-constrained operation • Limited physical security

  5. Background • Table-driven routing protocols • Routing • Disadvantages • On-demand routing protocols • Routing • Disadvantages • Cluster-based routing protocols (Laura Feeney, Infocom 2001) • Routing • Disadvantages

  6. DSDV Routing Protocol

  7. Return DSDV Routing Protocol (Cont’d)

  8. Return Disadvantages of Table Driven Protocols • Routing is achieved by using routing tables maintained by each node • The bulk of the complexity in generating and maintaining these routing tables • If the topological changes are very frequent, incremental updates will grow in size

  9. DATA DATA 1,2,8 1,2,5,8 5,2,1 8,5,2,1 2,1 DATA 1,3,4,8 1,3,4,7,8 1,8 1,3,4,8 1,3,8 1,8 1,3,6,8 1,3,8 On-demand Routing Protocol (DSR) D X S

  10. X X Return AODV Routing Protocol DATA D DATA DATA DATA timeout DATA S

  11. Return Disadvantages of On-demand Protocols • Not scalable to large networks, because of the source routing requirement. Furthermore, the need to place the entire route in both route replies and data packets causes a significant overhead. • Some of them requires symmetric links between nodes, and hence cannot utilize routes with asymmetric links.

  12. Cluster-based Routing Transmission Range of MT 1

  13. Cluster-based Routing.. Range of MT 1

  14. Cooperative Routing vs Direct Sending Power-aware localized routing in wireless networks Stojmenovic, I.; Lin, X.; Parallel and Distributed Systems, IEEE Transactions on Volume 12, Issue 11, Nov. 2001 Page(s):1122 – 1133 • In simple radio model, a radio dissipates Eele = 50 nJ/bit at the sender and receiver sides. Let us assume the d is the distance between the source and destination, then, the energy loss is d2. The transmit amplifier at the sender consumes Eampd2, where Eamp = 100 pJ/bit/m2. Therefore, from the sender side, to send one bit at distance d, the required power is Eele + Eampd2, whereas at the receiver will need is Eele only. Normalizing both by dividing by Eamp: • Pt = E + d2 and Pr = E, where Pt and Pr are the normalized transmission and reception power respectively, and E = Eele / Eamp = 500m2 • At the HCB-model, the power needed for transmission and reception at distance d is: u(d) = Pt + Pr = 2E + d2 u(d) = adα + c

  15. Cooperative Routing vs Direct Sending.. • Where in HCB-model α = 2, a = 1, and c = 2E = 1,000 • Let us assume that the source S can reach the destination D directly. Let us further assume that there is a middle node between the source and the destination. Let |SA| = x and |SD| = d as in the below Figure • Ifd > (c/(a(1-21-α)))1/α, then there is an intermediate node A between the source and destination such that the retransmission of the packet through A will save the energy. Moreover, the greatest saving is achieved when A in the middle of SD.

  16. Cooperative Routing vs Direct Sending.. • Also if d > (c/(a(1-21-α)))1/α, then the greatest power saving are obtained when the interval SD is divided into n > 1 equal subintervals, where n is the nearest integer to d(a(α-1)/c)1/α.

  17. Cooperative Routing vs Direct Sending.. • Now the power needed for direct transmission is u(d) = adα + c, which is optimal when d≤(c/(a(1-21-α)))1/α, otherwise when d>(c/(a(1-21-α)))1/α, n-1 is equally spaced nodes can be selected for transmission, • Where, n = d(a(α-1)/c)1/α • The minimal power: v(d) = dc(a(α-1)/c)1/α + da(a(α-1)/c)(1-α)/α

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