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**Mobile Computing COE 446Mobile Ad hoc NetworksTarek SheltamiKFUPMCCSECOEhttp://faculty.kfupm.edu.sa/coe/tarek/coe446.htm
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**Many ApplicationsPersonal area networkingcell phone, laptop, ear phone, wrist watchMilitary environmentssoldiers, tanks, planesCivilian environmentstaxi cab networkmeeting roomssports stadiumsboats, small aircraftEmergency operationssearch-and-rescuepolicing and fire fighting
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**Why Ad hoc Networks?No infrastructure needed (no routing in fixed wireless)Can be deployed quickly, where there is no wireless communication infrastructure presentCan act as an extension to existing networks enhances coverageCost-effective cellular spectrum costs $XX billionAdaptive computing and self-configuringSupport for heterogeneous computational devices and OSs
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**Ad hoc Constraints Dynamic topologiesBandwidth-constrained Constraints on Tx power Infrastructure-less property, no central coordinators hidden terminal, exposed terminalNo QoS preservationLoad balancing Energy-constrained operation Limited physical security
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**BackgroundTable-driven routing protocolsRoutingDisadvantagesOn-demand routing protocolsRouting DisadvantagesCluster-based routing protocols (Laura Feeney, Infocom 2001)RoutingDisadvantages
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**DSDV Routing Protocol
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**DSDV Routing Protocol (Contd)
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**Disadvantages of Table Driven ProtocolsRouting 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
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**SDOn-demand Routing Protocol (DSR)X
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**timeout AODV Routing ProtocolDSDATADATADATADATADATA
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**Disadvantages of On-demand ProtocolsNot 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.
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** Cluster-based RoutingTransmission Range of MT 1
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**Cluster-based Routing..Range of MT 1
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**Cooperative Routing vs Direct SendingIn 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 + d2u(d) = ad + c
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
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**Where in HCB-model = 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
If d > (c/(a(1-21-)))1/, 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. Cooperative Routing vs Direct Sending..
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**Also if d > (c/(a(1-21-)))1/, 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(-1)/c)1/.
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**Now the power needed for direct transmission is u(d) = ad + c , which is optimal when d(c/(a(1-21-)))1/, otherwise when d>(c/(a(1-21-)))1/, n-1 is equally spaced nodes can be selected for transmission,Where, n = d(a(-1)/c)1/ The minimal power:v(d) = dc(a(-1)/c)1/ + da(a(-1)/c)(1-)/
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