Wireless Networks Routing

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Wireless Networks Routing
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Outlines

• Wireless networks architectures
• Routing protocols for wireless networks
• Mobile ad-hoc Networks (MANETs)
• Wireless Sensor Networks (WSNs)
• Vehicle ad-hoc networks (VANETs)

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Wireless Communications

• Wireless networks use radio frequency channels as
  their physical medium for communications.
• Each node in the network broadcast information
  which can be received by all nodes within its
  direct transmission range.

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Wireless network architectures

• Infrastructure-based wireless networks
• Fixed base stations / access points are used.
• Infrastructure-less wireless networks (Ad-hoc
  networks)
• No fixed infrastructure support are available.
• Hybrid wireless networking architecture

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Wireless network architectures (cont.)

• Infrastructure-based wireless networks
• Uses fixed base stations / access points which
  are responsible for coordinating communication
  between the hosts.
• Single-hop communication

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Wireless network architectures (cont.)

• Ad-hoc networks
• Consists of nodes which communicate with each
  other through wireless medium without any fixed
  infrastructure.
• Multi-hop communications

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Properties of ad-hoc networks

• No pre-build infrastructure
• All nodes are wireless capable
• Base stations are not necessary
• Ease of deployment
• Quickly deploy

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Some emerging types of wireless networks

• MANETs (Mobile Ad-hoc Networks)
• WSNs (Wireless Sensor Networks)
• VANET (Vehicle Ad-hoc Networks)
• WMN (Wireless Mesh Networks)

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Routing protocols for wireless networks MANETs

• A dynamically reconfigurable ad-hoc network.
• Main issues in the design and operation of
  MANETs.
• (1) MANETs are more unstable than wired-networks
  because of the lack of a centralized
  entity.

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Routing protocols for wireless networks MANETs
(cont.)

• (2) Mobility will cause network topology to
  change, which results in a great change in
  connection between two hosts.
• (3) The connectivity between network nodes is
  not guaranteed, so intermittent
  connectivity is common.

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The main routing problems for MANETs
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Node mobility ? Routing path broken frequently
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3
5
1
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Traditional ad-hoc routing protocols
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Routing protocols for MANETs

• Flooding-type routing protocol (flooding)
• Table-driven routing protocol (proactive)
• On-demand routing protocol (reactive)
• Hybrid routing protocol

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Flooding-type routing protocol (Flooding)
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Flooding-type routing protocol (Flooding)

• Advantage They do not need to maintain network
• topology, or is looking for data transmission
  path, so
• they can quickly transfer information.
• Disadvantage Node receives information after,
  must
• repeat broadcast, making it fast consumes its
  battery energy, and produces broadcast storm.

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Routing protocols for MANETs (cont.)

• Table-driven routing protocol (proactive)
• They maintain the global topology information in
  the
• form of tables at every node.
• These tables are updated frequently in order to
• maintain consistent and accurate network state
• information.
• For example, DSDV, WRP, and STAR.

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Table-driven routing protocolDestination
Sequenced Distance Vector routing (DSDV)

• The DSDV routing protocol is an enhanced version
  of the distributed Bellman-Ford algorithm where
  each node maintain a table that contain the
  shortest distance and the first node on the
  shortest path to every other node in the network.

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Table-driven routing protocol DSDV (cont.)
Example
Routing table for Node 1
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Dest NextNode Dist seqNo
2 2 1 22
3 2 2 26
4 5 2 32
5 5 1 134
6 6 1 144
7 2 3 162
8 5 3 170
9 2 4 186
10 6 2 142
11 6 3 176
12 5 3 190
13 5 4 198
14 6 3 214
15 5 4 256
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13
11
12
9
10
8
6
4
7
5
3
1
2
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Table-driven routing protocol DSDV (cont.)

• Each node, upon receiving an update, quickly
  disseminates it to its neighbors in order to
  propagate the broken-link information to the
  whole network. Thus a single link break leads to
  the propagation of table update information to
  the whole network.

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Table-driven routing protocol DSDV (cont.)
Routing table for Node 1
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Dest NextNode Dist seqNo
2 2 1 22
3 2 2 26
4 5 2 32
5 5 1 134
6 6 1 144
7 2 3 162
8 5 3 170
9 2 4 186
10 6 2 142
11 5 4 180
12 5 3 190
13 5 4 198
14 6 3 214
15 5 4 256
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13
11
12
10
8
9
6
7
4
5
3
1
2
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Table-driven routing protocol DSDV (cont.)

• Advantage
• It can be applied to MANETs with few
  modifications. The updates are propagated
  throughout the network in order to maintain an
  up-to-date view of the network topology at all
  the nodes.

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Table-driven routing protocol DSDV (cont.)

• Disadvantage
• (1) The DSDV suffers from excessive control
  overhead that is proportional to the number of
  nodes in the network and therefore is not
  scalable in MANETs, which have limited
  bandwidth and whose topologies are highly
  dynamic.

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Table-driven routing protocol DSDV (cont.)

• (2) In order to obtain information about a
  particular destination node, a node has to
  wait for a table update message initiated
  by the same destination node. This delay
  could result in stale routing information
  at nodes.

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Routing protocols for MANETs (cont.)

• On-demand routing protocol (reactive)
• They execute the path-finding process and
  exchange routing information only when a path is
  required by a node to communicate with a
  destination.
• For example, AODV and DSR.

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On-demand routing protocol Ah-hoc On-demand
Distance-Vector Routing Protocol (AODV)

• AODV, a route is established only when it is
  required by a source node for transmitting data
  packets.
• In AODV, the source node and intermediate nodes
  store the next-hop information corresponding to
  each flow for data packet transmission.

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On-demand routing protocol AODV (cont.)

• The major difference between AODV and other
  on-demand routing protocol is that it uses a
  destination sequence number ( DestSeqNum) to
  determine an up-to-date path to the destination.
• A node updates its path information only if the
  DestSeqNum of the current packet received is
  greater than the last DestSeqNum stored at the
  node.

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On-demand routing protocol AODV (cont.)

• AODV utilizes routing tables to store routing
  information.
• The routing table stores

destination addr next-hop addr destination sequence hop count life time
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The AODV routing procedure

• 1. If a node wants to send a packet to some
  destination. At first, it checks its routing
  table to determine whether it has a current route
  to the destination or not.
• gtIf yes, it forwards the packet to next hop
  node of the route.
• gtIf no, it initiates a route discovery
  process.

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The AODV routing procedure (cont.)

• The Route discovery process
• It begins with the creation of a RouteRequest
  (RREQ) packet. Broadcasting is done via flooding.
• Broadcast ID gets incremented each time a source
  node uses RREQ.
• Broadcast ID and source IP address form a unique
  identifier for the RREQ.

Type Reserved Hop Count
 Broadcast ID   Broadcast ID   Broadcast ID 
Destination IP Address Destination IP Address Destination IP Address
Destination Sequence Number Destination Sequence Number Destination Sequence Number
Source IP Address Source IP Address Source IP Address
Source Sequence Number Source Sequence Number Source Sequence Number
Time Stamp Time Stamp Time Stamp
RREQ packet format
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The AODV routing procedure (cont.)

• 2. Sender S broadcasts a RREQ to all its
  neighbors, each node receiving RREQ forwards RREQ
  to its neighbors.
• Sequence numbers help to avoid the
  possibility of forwarding the same packet
  more than once.
• 3. An intermediate node (not the destination) may
  also send a RouteReply (RREP) packet provided
  that it knows a more recent path than the one
  previously known to sender S.

Type Reserved Hop Count
Destination IP Address Destination IP Address Destination IP Address
Destination Sequence Number Destination Sequence Number Destination Sequence Number
Source IP Address Source IP Address Source IP Address
Life Time Life Time Life Time
RREP packet format
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The AODV routing procedure (cont.)

• 4. As an intermediate node receives the RREP
  packet, it sets up a forward path entry
  to the destination in its routing table.
• 5. The source node can begin data transmission
  upon receiving the first RREP.

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Illustration of route establishment in AODV

• 1. Node S needs a routing path to node D.
• 2. Node S creates a RREQ packet
• RREQ Ds IP addr, seq, Ss IP addr,
  seq, hopcount
• Node S broadcasts RREQ to its neighbors.

B
RREQD, Dseq, S, Sseq, 0
S
A
D
C
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Illustration of route establishment in AODV
(cont.)

• 2. Node A rebroadcasts RREQ to all its neighbors.

B
RREQD, Dseq, S, Sseq, 1
S
A
D
RREQD, Dseq, S, Sseq, 1
C
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Illustration of route establishment in AODV
(cont.)

• 3. Since, node C known a route to D.
• Node C creates a RREP packet and unicasts RREP to
  A.
• Set forward path in node Cs routing table.

B
S
A
RREPD, Dseq, S, Sseq, 1
D
C
Cs Routing table Cs Routing table Cs Routing table
dest nexthop hopcount
D D 1
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Illustration of route establishment in AODV
(cont.)

• 3. Node A creates a RREP packet and unicasts RREP
  to S.
• 4. Set forward path in node As routing table.

As Routing table As Routing table As Routing table
dest nexthop hopcount
D C 2
B
S
A
D
RREPD, Dseq, S, Sseq, 2
C
Cs Routing table Cs Routing table Cs Routing table
dest nexthop hopcount
D D 1
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Illustration of route establishment in AODV
(cont.)

• 4. Set forward path in node Ss routing table.

As Routing table As Routing table As Routing table
dest nexthop hopcount
D C 2
B
S
A
D
Ss Routing table Ss Routing table Ss Routing table
dest nexthop hopcount
D A 3
C
Cs Routing table Cs Routing table Cs Routing table
dest nexthop hopcount
D D 1
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Route maintenance in AODV (Path broken due to
host mobility)

• 1. If intermediate nodes or the destination move.
• ?The next hop links break.
• ?Routing tables are updated for the link
  failures.
• ?All active neighbors are informed by
  RouteError (RRER) packet.
• 2. When a source node receives an RRER, it can
  reinitiate the route discovery process.
• 3. It can be also dealt with by a local fix
  scheme.

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Illustration of route maintenance in AODV

• Assume link between C and D breaks.
• Node C invalidates route to D in route table.
• Node C creates RRER packet and sends to its
  upstream neighbors.
• Node A sends RRER to S.
• Node S rediscovers route if still needed.

B
RRER
S
A
RRER
D
C
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On-demand routing protocol AODV (cont.)

• Advantage
• The routes are established on demand and the
  destination sequence number can find the latest
  route to the destination.
• Disadvantage
• The intermediate nodes can lead to inconsistent
  routes if the source sequence number is very old.
  
• The periodic beaconing leads to unnecessary
  bandwidth consumption.

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On-demand routing protocol Dynamic Source
Routing Protocol (DSR)

• DSR designed to restrict the bandwidth consumed
• by control packets in ad hoc wireless networks
  by
• eliminating the periodic table-update messages
• required in the table-driven approach.

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Route Discovery (broadcasting the RREQ packets)
lt1,2gt
lt1,3,5,7gt
lt1,3,5gt
lt1gt
Destination
lt1gt
lt1,3gt
Source
lt1,4,6gt
lt1gt
lt1,4gt
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Route Discovery (cont.) (propagating the RREP
packets back to source)
lt1,3,5, 7gt
lt1,3,5, 7gt
lt1,3,5, 7gt
lt1,3,5, 7gt
Destination
lt1,3,5, 7gt
lt1,3,5, 7gt
Source
lt1,4,6gt
lt1,4,6gt
lt1,4,6gt
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Hybrid routing protocol Zone Routing Protocol
(ZRP)

• A hybrid routing protocol which effectively
  combines the best features of both proactive and
  reactive routing protocols.
• The key concept employed in ZRP is to use a
  proactive routing scheme within a limited zone in
  the ?-hop neighborhood of every node, and use a
  reactive routing scheme for nodes beyond this
  zone.

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Routing zone for node 8 in ZRP
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8
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7
4
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Routing Zone with Radius 1
3
1
2
Routing Zone with Radius 2
Routing Zone for Node 8
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Performing the Proactive Routing for node 8
(destinationnode 16)
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14
13
11
12
16
8
10
9
4
6
RouteRequest
7
5
RouteReply
3
2
1
Routing Zone with Radius 2
Routing Zone for Node8
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Hybrid routing protocol ZRP (cont.)

• Advantage
• By combining the best features of proactive and
  reactive routing schemes, ZRP reduces the control
  overhead.
• Disadvantage
• But in the absence of a query control, ZRP tends
  to produce higher control overhead than the
  previously schemes.

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Other routing issue for MANET The Intermittent
connected routing problem

• In case of the nodes density of a MANET is
  sparse, it will cause the intermittent connected
  routing problem, and consequently the traditional
  routing protocols will be no longer fit.

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Intermittent connected routing problem
 
 
 
 
 
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Epidemic routing protocol

• Epidemic is a simple routing protocol to resolve
  the intermittent connected routing problem.
• The nodes adopt store-carry-forward communication
  scheme.
• A node can carry the messages in its cache if no
  any direct routing path to the destination is
  available.
• If a node moves into the nodes transmission
  range, they will exchange the carried messages
  between them.

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3
5
2
4
1
(Epidemic routing)
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Routing protocols for wireless networks WSNs

• A sensor network is composed of a large number of
  multifunctional and small sensor nodes.
• WSN allows random deployment in inaccessible
  terrains or disaster relief operations.
• Sensor nodes are fitted with an onboard
  processor, it consists of sensing, data
  processing, and communicating components.

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Introduction to WSNs -- Communication architecture
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Introduction to WSNs -- Communication
architecture (cont.)
Satelite
Sink
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Introduction to WSNs -- Communication
architecture (cont.)

• The sensor nodes are usually scattered in a
  sensor field.
• Sensor nodes can collect data and route data back
  to sink.
• The sink may communicate with the task manager
  node via Internet or Satellite.

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Introduction to WSNs -- Applications
Military applications
Home applications
Environmentalapplications
Applications
Other commercial applications
Health applications
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Introduction to WSNs The differences between
WSNs and ad-hoc networks

• The number of sensor nodes in a sensor network
  can be several orders of magnitude higher.
• Sensor nodes are densely deployed.
• Sensor nodes are prone to failures.
• Sensor nodes are limited in power, computational
  capacities, and memory.

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Introduction to WSNs The differences between
WSNs and ad-hoc networks (cont.)

• Sensor nodes mainly use a broadcast communication
  paradigm, whereas most ad hoc networks are based
  on point-to-point communications.
• Sensor nodes may not have global identification
  (ID) because of the large amount of overhead and
  large number of sensors.

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Introduction to WSNs Sensor node
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Introduction to WSNs Sensor node (cont.)
Aqua node
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Introduction to WSNs Sensor node (cont.)
Aqua node
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Introduction to WSNs Sensor node (cont.)
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Introduction to WSNs Design factors

• Production costs
• The cost of each sensor node should be much less
  than US 1 in order for the sensor network to be
  feasible.
• Transmission media
• In a multi-hop sensor network, communicating
  nodes are linked by radio, infrared or optical
  media.

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Introduction to WSNs Design factors (cont.)

• Environment
• Sensor network usually work unattended in remote
  geographic areas, such as large machinery, ocean,
  biologically and chemically contaminated field.
• Hardware
• A sensor node is made up of four basic
  components sensing unit, processing unit,
  transceiver unit, power unit, and also have
  additional application-dependent components.

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Introduction to WSNs Network deployment

• Three phases of WSNs deployment
• Pre-deployment phase
• Sensor nodes can be either thrown in mass or
  placed one by one in the sensor field.
• Post-deployment phase
• After deployment, topology changes are due to
  change in sensor nodes
• Position
• available energy
• malfunctioning

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Introduction to WSNs Network deployment (cont.)

• Re-deployment phase
• Additional sensor nodes can be re-deployed at any
  time to replace the malfunctioning nodes or due
  to changes in task dynamics.
• Addition of new nodes poses a need to re-organize
  the network.

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Introduction to WSNs Routing challenges and
design issues

• Node deployment
• In manual deployment, the sensors are manually
  placed and data is routed through predetermined
  paths.
• Energy consumption without losing accuracy
• Sensor nodes can use up their limited energy
  performing computations and transmitting
  information.

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Introduction to WSNs Routing challenges and
design issues (cont.)

• Data reporting method
• Data reporting can be categorized as either
  time-driven, event-driven, query-driven, or a
  hybrid.
• The time-driven method is suitable for
  applications that require periodic data.
• Event-driven and query-driven methods, sensor
  nodes react immediately to sudden and drastic
  changes in the value of a sensed attribute

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Introduction to WSNs Routing challenges and
design issues (cont.)

• Coverage
• A given sensors view of the environment is
  limited in both range and accuracy.
• Area coverage is an important design parameter.
• Quality of service
• Bounded latency for data delivery is another
  condition for time-constrained applications.
• As energy is depleted, the network may be
  required to reduce the quality of results in
  order to reduce energy dissipation.

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Routing protocols for WSNs (cont.)

• Flat-based
• All nodes are typically assigned equal roles or
  functionality.
• Hierarchical-based
• Nodes will play different roles in the network.
• Location-based
• Sensor nodes positions are exploited to route
  data in the network.

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Routing protocols for WSNs (cont.)Flat-based
routing

• Each node typically plays the same role and
  sensor nodes collaborate to perform the sensing
  task.
• This consideration has led to data-centric
  routing, where the BS sends queries to certain
  regions and waits for data from the sensors
  located in the selected regions.
• Early work on data centric routing were shown to
  save energy through data negotiation and
  elimination of redundant data.

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Flat-based routing exampleSPIN (Sensor Protocols
for Information via Negotiation)
A

1. Data is described by meta-message (ADV).
2. Send ADV to neighbors.
3. If neighbor do not have the data, sends REQ
   otherwise, do nothing.
4. As the REQ received by sender, then it sends the
   data to the neighbor.

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Flat-based routing exampleSPIN (cont.)

• Advantage
• Each node only needs to know its one-hop
  neighbors.
• Disadvantage
• Data advertisement cannot guarantee the delivery
  of data.

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Routing protocols for WSNs (cont.) Hierarchical-ba
sed routing

• Hierarchical routing is two-layer routing where
  one layer is used to select cluster heads and the
  other for routing.
• Higher-energy nodes can be used to process and
  send the information, while low-energy nodes can
  be used to perform the sensing in the proximity
  of the target.
• The creation of clusters and assigning special
  tasks to cluster heads can greatly contribute to
  overall system scalability, lifetime, and energy
  efficiency.

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• Proactive clustering.
• Node transmits sensed data only if both of the
  following conditions hold
• 1. The sensed value is greater than a Hard
  Threshold.
• 2. The sensed value differs from last transmitted
  value by more than a Soft Threshold.

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Hierarchical-based routing exampleTEEN
(Threshold-Sensitive Energy Efficient Sensor
Network Protocol)
S
Sink
Cluster
D
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Hierarchical-based routing exampleTEEN (cont.)

• Advantage
• Good for time-critical applications.
• Disadvantage
• Inappropriate for periodic monitoring, e.g.,
  habitat monitoring.
• Ambiguity between packet loss and unimportant
  data.

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Routing compare
Hierarchical-based routing Flat-based routing
Reservation-based scheduling Contention-based scheduling
Collisions avoided Collision overhead present
Reduced duty cycle due to periodic sleeping Variable duty cycle by controlling sleep time of nodes
Data aggregation by cluster head Node on multi-hop path aggregates incoming data from neighbors
Simple but non-optimal routing Routing can be made optimal but with an added complexity
Requires global and local synchronization Links formed on the fly without synchronization
Overhead of cluster formation throughout the network Routes formed only in regions that have data for transmission
Lower latency as multiple hops network formed by cluster heads always available Latency in waking up intermediate nodes and setting up the multipath
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Routing protocols for WSNs (cont.)Location-based
routing

• The location of nodes may be available directly
  by communicating with a satellite using GPS if
  nodes are equipped with a small low-power GPS
  receiver.
• Relative coordinates of neighboring nodes can be
  obtained by exchanging such information between
  neighbors.
• To save energy, some location-based schemes
  demand that nodes should go to sleep if there is
  no activity.

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Routing protocols for wireless networks VANETs

• Vehicular Ad hoc Network (VANET) is a special
  case of MANET.
• The direct communication between vehicular using
  Ad hoc network.

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Introduction to VANETs

• Applications in a VANET fall into two categories
• comfort applications
• safety applications
• Comfort applications aim to improve the driving
  comfort and the efficiency of the transportation
  system
• on-board Internet access
• high data rate content download
• driving through payment

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Introduction to VANETs (cont.)

• Safety applications aim to provide drivers
  information about future critical situations
• inter-vehicle danger warning
• intersection collision avoidance
• work zone safety warning

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Safety applications
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Introduction to VANETs (cont.)

• VANETs provide the following three
  communications
• Inter-Vehicle Communication (IVC)
• Roadside-to-Vehicle Communication (RVC)
• Hybrid-Vehicular Communication (HVC)

V2R
Emergency Event
V2V
RSU
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Introduction to VANETs (cont.)

• Vehicles mobility is restricted to
  one-dimensional road geometry.
• Factors affect the mobility of vehicles such as
• road configuration
• traffic laws
• safety limits
• physical limits

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Introduction to VANETs (cont.)

• Vehicle mobility creates a highly dynamic
  topology.
• VANETs are potentially large-scale networks.
• Vehicles can provide more resources than other
  types of mobile networks such as
• large batteries
• antennas
• processing power

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Introduction to VANETs (cont.)

• The connectivity of the network is affected by
  factors that include
• transmitter power
• environmental conditions
• obstacles
• mobility

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Introduction to VANETs (cont.)

• Factors such as the vast number of nodes that
  lack inherent organization, as well as
• frequent topological changes

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Routing for VANETs

• To enhance the safety of drivers
• To provide the comfortable driving environment
• The message for different purpose need to be sent
  to vehicles through the inter-vehicle
  communications.
• Unicast routing
• Multicast and Geocast
• Broadcast

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Routing for VANETs -- Unicast

• Unicast routing is a fundamental operation for
  vehicle to construct a source-to-destination
  routing in a VANET

From Reference 1.
90
Routing for VANETs -- Unicast

• Routing objective Min-Delay
• The goal of min-delay routing protocols is to
  transmit data packets to destination as soon as
  possible.
• Relative routing protocolsVADD?CAR?DIR

91
Unicast routing example for VANETsVehicle-Assiste
d Data Delivery (VADD)

• Carry-and-forward for data delivery from a moving
  vehicle to a static destination.
• VADD is to select a forwarding path with the
  smallest packet delivery delay.

92
Unicast routing example for VANETs The VADD
(cont.)
(1) Ia gt Ic gt Id gt Ib
Two Paths
Disconnected due to sparse
(2) Ia gt Ib
Delayacdb lt Delayab
93
Unicast routing example for VANETs The VADD
(cont.)

1. Transmit through wireless channels as much as
   possible.
2. If the packet has to be carried through certain
   roads, the road with higher speed should be
   chosen.

94
Unicast routing example for VANETs The VADD
(cont.)

• Due to the unpredictable nature of vehicular
  ad-hoc networks, so dynamic path selection should
  continuously be executed throughout the packet
  forwarding process.
• The routing cannot expect the packet to be
  successfully routed along the pre-computed
  optimal path

95
Unicast routing example for VANETs Connectivity-Aw
are Routing (CAR)

• To overcome the limitation of the static
  destination.
• The CAR protocol establishes a routing path from
  source to destination by setting the anchor
  points at intermediate junctions.

96
Unicast routing example for VANETs The CAR (cont.)

• CAR protocol sends the searching packets to find
  the destination.
• Each forwarding vehicle records its ID, hop
  count, and average number of neighbors in
  searching packets.
• Once the searching packets reach the destination,
  the destination chooses a routing path with the
  minimum delivery delay time and replies it to the
  source.

97
Unicast routing example for VANETs The CAR (cont.)

• While destination sends the reply packet to the
  source, the junctions passed through by the reply
  packet are set as the anchor point.
• After the path set up, data packets are forwarded
  in a greedy forwarding.

D
Greedy forwarding example x the current
message holder. Assume y is the closest neighbor
of x to D, then x sends the message to y.
x
y
98
Unicast routing example for VANETs An example for
CAR (cont.)

• Vehicle VS tries to send data to vehicle VD, the
  anchor points are set at I1,1, I2,1, I2,2, I3,2,
  I3,3, and I3,4.
• Data is forwarded according to order in the list
  of anchor points.

99
Unicast routing example for VANETsDiagonal-Inters
ection-based Routing (DIR)

• To improve the CAR protocol.
• DIR protocol constructs a series of diagonal
  intersections between the source and destination
  vehicles.
• Auto-adjustability is achieved that one sub-path
  with low data packet delay, between two
  neighboring diagonal intersections, is
  dynamically selected to forward data packets.

100
Unicast routing example for VANETsThe DIR (cont.)

• To reduce the data packet delay, the route is
  automatically re-routed by the selected sub-path
  with lowest delay.
• DIR protocol constructs a series of diagonal
  intersections between vehicles VS and VD.

101
Unicast routing example for VANETsThe
comparisons between CAR and DIR

• DIR protocol may set the fewer number of anchors
  than CAR protocol.
• DIR protocol can automatically adjust routing
  path for keeping the lower packet delay, compared
  to CAR protocol.

102
Routing for VANETs Multicast and Geocast

• Multicast is defined by delivering multicast
  packets from a single source vehicle to all
  multicast members by multi-hop communication.
• Geocast routing is to deliver a geocast packet to
  a specific geographic region.

Geocast Routing
103
Broadcast routing for VANETs

• Broadcast protocol is utilized for a source
  vehicle sends broadcast message to all other
  vehicles in the network.
• Routing protocol typeBroadcast methods for V2V
  communication

Advertisement Publicity Broadcast
104
Broadcast outing for VANETs (cont.)

• The purpose of emergency information is to
  announce an urgent event by broadcasting for
  surrounding vehicles.
• emergency-vehicle-approach
• traffic accident information dissemination

105
Broadcast routing for VANETs (cont.)

• Emergency-vehicle-approach
• Emergency-vehicle-approach information is used to
  announce the urgent event to those vehicles in
  front of the current vehicle, so the emergency
  information is only disseminated ahead.
• Traffic accident information dissemination
• Traffic accident information is used to announce
  the urgent event to those vehicles behind the
  current vehicle, the emergency information is
  only disseminated behind.

106
Broadcast routing for VANETs (emergency message
distribution)

1. Vehicle VA broadcasts the emergency message to
   the restricted direction.
2. Vehicle VD does nothing.

107
Broadcast routing for VANETs --emergency
message distribution (cont.)

1. Vehicle VB is located in the relay range, it
   re-broadcasts the emergency information.
2. Vehicle VC is located in notification range but
   not in relay range, VC just receives the
   emergency information and not to re-broadcast.

108
References

• I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, and
  E. Cayirci, "Wireless sensor network a survey",
  Computer Networks, Vol. 38, pp. 393-422, 2002.
• I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, and
  E. Cayirci, "A survey on sensor networks", IEEE
  Communications Magazine, Vol. 40, issue 8, pp.
  102-114, Aug. 2002.
• J. N. Karaki, A. E. Kamal, "Routing techniques in
  wireless sensor networks a survey", IEEE
  Wireless Communications, pp. 6-28, Dec. 2004.
• J. Zhao and G.Cao, VADD vehicle-assisted data
  delivery in vehicular ad hoc networks, IEEE
  Computer Communications, pp. 1-12, 2006.
• V. Naumov and T. Gross, Connectivity-aware
  routing (CAR) in vehicular ad hoc Networks, in
  Proceedings of IEEE International Conference on
  Computer Communications, pp.1919-1927, 2007.
• Y. W. Lin, Y. S. Chen and S. L. Lee, Routing
  protocols in vehicular ad hoc networks a survey
  and future perspectives, Journal of Information
  Science and Engineering 26, pp.1-20, 2010.

109
References

• M. S. Bouassida and M. Shawky, A cooperative
  congestion control approach within VANETs
  formal verification and performance evaluation,
  EURASIP Journal on Wireless Communications and
  Networking, Vol. 2010, 2010.
• http//commonsense.epfl.ch/COMMONSense/description
  .htm
• http//groups.csail.mit.edu/drl/wiki/index.php/AMO
  UR_(Autonomous_Modular_Optical_Underwater_Robot)
• http//russnelson.com/wisan/Sensor-node-front.jpg
• http//www.ece.ncsu.edu/wireless/Images/sensor.gif
  
• http//blogs.iium.edu.my/jaiz/2008/12/22/what-is-v
  ehicular-network/