june 2, 20141 mobile computing coe 446 mobile ad hoc networks tarek sheltami kfupm ccse coe
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April 10, 2023 1
Mobile Computing COE 446
Mobile Ad hoc NetworksTarek Sheltami
KFUPMCCSECOE
http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm
April 10, 2023 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
April 10, 2023 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
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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
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Background
Table-driven routing protocols Routing Disadvantages
On-demand routing protocols Routing Disadvantages
Cluster-based routing protocols (Laura Feeney, Infocom 2001)
Routing Disadvantages
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DSDV Routing Protocol
2 13 44 46 15
DEST Next hop1 4
5
1 13 59 8
10 12
DEST Next hop
1
Source
Destination
2 13 34 47 9
DEST Next hop
3
April 10, 2023 7
DSDV Routing Protocol (Cont’d)
2 1
3 4
DESTNexthop
Metric#
4
Seq #
8
2 1
3 4
DESTNexthop
Metric#
4
Seq #
8
2 1
3 4
DESTNexthop
Metric#
4
Seq #
8
DEST 2Next hop 3Metric # 4
Sequence # 7
DEST 2Next hop 3Metric # 6
Sequence # 8
DEST 2Next hop 16Metric # 9
Sequence # 9
+
+
+
=
=
=
Ignore update
Ignore update
2 163 4
DESTNexthop
Metric#
9
Seq #
9
Table Updated
ReturnReturn
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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
ReturnReturn
April 10, 2023 9
1
2
3
4
5
6
7
8
S
D
On-demand Routing Protocol (DSR)
1,8
1,8
1,3,8
1,2,8
1,3,8
1,3,
4,7,
8
1,2,5,8
1,3,
4,8
1,3,4,8
1,3,6,8
8,5,2,15,2,1
2,1
XDAT
A
DATA
DATA
April 10, 2023 10
timeout
AODV Routing Protocol
1
2
3
4
5
6
7
8
D
S
X
X
DATA
DATA
DATA
DATA
DATA
ReturnReturn
April 10, 2023 11
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. ReturnReturn
April 10, 2023 12
Cluster-based Routing
Transmission Range of MT 1
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Cluster-based Routing..
3
1
2 6
4
5
7
Range of MT 1
April 10, 2023 14
Cooperative Routing vs Direct Sending
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) = adu(d) = adαα + c + 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
April 10, 2023 15
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
If d > (c/(a(1-2d > (c/(a(1-21-α1-α))))))1/α1/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.
S x d - x
d
S A D
Cooperative Routing vs Direct Sending..
April 10, 2023 16
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Also if d > (c/(a(1-2d > (c/(a(1-21-α1-α))))))1/α1/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)d(a(α-1)/c)1/α1/α.
Cooperative Routing vs Direct Sending..
S
d
S D
S d/nd/n d/nd/n
April 10, 2023 18
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Now the power needed for direct transmission is u(d) = adu(d) = adαα + c + c , which is optimal when d≤d≤(c/(a(1-2(c/(a(1-21-α1-α))))))1/α1/α, otherwise when d>d>(c/(a(1-2(c/(a(1-21-α1-α))))))1/α1/α, n-1 is equally spaced nodes can be selected for transmission,
Where, n = d(a(α-1)/c)n = d(a(α-1)/c)1/α1/α The minimal power:v(d) = dc(a(α-1)/c)v(d) = dc(a(α-1)/c)1/α1/α + da(a(α-1)/c) + da(a(α-1)/c)(1-α)/α(1-α)/α
Cooperative Routing vs Direct Sending..
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