This document discusses wireless ad hoc and sensor networks and routing protocols. It begins by defining routing as the process of moving data packets from a source to destination, which is usually performed by routers. Common objectives of routing protocols are to route packets along optimal paths while adapting to changing network conditions. Routing protocols are then categorized as link-state or distance-vector protocols. The document also discusses the purposes and challenges of routing in wireless ad hoc networks, as well as requirements for ad hoc routing protocols. Finally, it provides an overview of different types of ad hoc unicast routing protocols, including table-driven, on-demand, and hybrid protocols.

1. Wireless Ad Hoc and Sensor Networks
CSE 5109
Sajeeb Saha
Assistant Professor
Dept. of CSE, JnU

2. Wireless Ad Hoc Routing
Protocols
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3. What is Routing?
– The process of moving a packet of data from source to
destination.
– Routing is usually performed by a dedicated device called
a router.
– Each intermediary computer performs routing by passing
along the message to the next computer.
– Part of this process involves analyzing a routing table to
determine the best path.
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4. Common objective:
Route packets along the optimal path
– Routing protocols adapt to changing network conditions and by
definition offers multi-hop paths
– Routing protocols differ in route table
 construction
 maintenance
 update
Next-hop routing protocols can be categorized as:
– Link-state
– Distance-vector
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Purpose of Routing

5. – [Dijkstra 1959 and McQuillan+ 1980]
– Traditional link-state protocols may not be suitable
– Closer to centralized version of shortest-path algorithm
– Each node maintains a view of network topology with a cost for each link
– Link costs are broadcast periodically to keep the views consistent
– Each node updates its view and applies a shortest-path algorithm to find its
next hop for each destination
– Routing loops may occur due to propagation delays, partitioned networks, and
so on
– Alternative link-state routing approaches may not require all nodes to have
the identical link-state information and route selection algorithms and may find
routes on demand
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Link State Routing
Distributed database problem

6. – [Ford+ 1962 and Leiner+ 1987]
– Based on shortest-path routing algorithms i.e., Distributed Bellman-
Ford
– DBF algorithms are also known as Distance-Vector (DV)
– Routers exchange their distances to known destinations;
– a router uses the distance vectors received from its neighbors to
compute its own distances.
– For each destination, the node stores a single route table entry along
with next-hop neighbor
– Route table entry for destination contains metric which is distance
from node to the destination and also the next-hop (vector) towards
destination
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Distance Vector Routing
Distributed computation problem

7. • Mobility
– Induced route changes
– Induced packet losses
– frequent network partitions
• Error-Prone Shared Broadcast Radio Channel
– Hidden/Exposed terminal problem
– Packet losses due to transmission errors
• Bandwidth Constraint
– Less data rate
– Minimum Control Information
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Challenges in Wireless Ad Hoc Routing

8. • Resource Constraint
– Battery Life
– Processing Power
• Security Hazard
– Ease of snooping on wireless transmissions
– Ease of denial-of-service attack
– Misbehaving nodes difficult to identify
– Nodes can be easily compromised
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Challenges in Wireless Ad Hoc Routing

9. 1. The routing protocol should be Distributed.
2. It must be adaptive to frequent topology changes.
3. Route computation and maintenance must involve a minimum
number of nodes.
4. It must be Localized.
5. The routes must be loop-free and stale-free.
6. The number of packet collisions must be kept to a minimum.
7. It must converge to a optimal route.
8. It must optimally use scarce resources such as bandwidth,
computing power, memory, and battery power.
9. It should be able to provide a certain level of quality of service
(QoS)
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Wireless Ad Hoc Routing Requirements

10. Ad-Hoc Mobile
Routing
Protocols
Table Driven /
Proactive
Hybrid
On-Demand-
Driven /
Reactive
DSDV
GSR
FSR
HSR
ZHLS
CGSR
WRP
AODV
DSR
TORA
CBRP
ABR
SSR
ZRP
Cluster
OLSR
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Wireless Ad Hoc Unicast Routing Protocols

11. Table Driven Routing Protocol
– proactive!!
– continuously evaluate the routes
– attempt to maintain consistent, up-to-date routing
information
• when a route is needed, one may be ready
immediately
– when the network topology changes
• the protocol responds by propagating updates
throughout the network to maintain a consistent
view
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12. • Proactive: maintain routing information
independently of need for communication
• Update messages send throughout the network
periodically or when network topology changes.
• Low latency, suitable for real-time traffic
• Bandwidth might get wasted due to periodic
updates
• They maintain O(N) state per node, N = #nodes
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Table Driven Routing Protocol

13. • DSDV – Destination-Sequenced Distance
Vector
• WRP – Wireless Routing Protocol
• GSR – Global State Routing
• FSR – Fisheye State Routing
• HSR – Hierarchical State Routing
• ZHLS – Zone-based Hierarchical Link State
Routing Protocol
• CGSR – Clusterhead Gateway Switch Routing
Protocol
Table Driven Routing Protocol

14. – reactive!!
– on-demand style: create routes only when it is
desired by the source node
• route discovery: invoke a route-determination
procedure
• the procedure is terminated when
– a route has been found
– no route is found after all route permutations
are examined
– longer delay: sometimes a route may not be ready
for use immediately when data packets come
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On Demand Routing Protocol

15. • Reactive: discover route only when you need it
• Saves energy and bandwidth during inactivity
• Can be bursty -> congestion during high activity
• Significant delay might occur as a result of route
discovery
• Good for light loads, collapse in large loads
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On Demand Routing Protocol

16. • AODV – Ad Hoc On-demand Distance
Vector Routing
• DSR – Dynamic Source Routing
• TORA – Temporally Ordered Routing
Algorithm
• CBRP – Cluster Based Routing Protocols
• ABR – Associativity Based Routing
• SSR – Signal Stability Routing
On Demand Routing Protocol

17. Hybrid Routing Protocols
• Proactive for neighborhood, Reactive for far
away (Zone Routing Protocol, Haas group)
• Proactive for long distance, Reactive for
neighborhood (Safari)
• Attempts to strike balance between the two
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18. Hierarchical Routing
• Nodes are organized in clusters
• Cluster head “controls” cluster
• Trade off
– Overhead and confusion for leader election
– Scalability: intra-cluster vs intercluster
• One or Multiple levels of hierarchy
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19. Geographical Routing
• Nodes know their geo coordinates (GPS)
• Route to move packet closer to end point
• Protocols DREAM, GPSR, LAR
• Propagate geo info by flooding (decrease
frequency for long distances)
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20. Ad Hoc Wireless Networks:
Architectures and Protocols
• Chapter 7
Suggested Reading
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21. THANK YOU