1. Mobile Ad Hoc Networks Part 1: Overview
NES540 Wireless Networks Protocols
Dr. Abdallah Alma’aitah
Department of Network Engineering & Security
Jordan University of Science and Technology
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

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Wireless Networks
Wireless networks can be classified as:
Infrastructure-based wireless networks
Infrastructure-less wireless networks
AKA “ad hoc wireless networks”
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

3. Infrastructure-based Wireless Networks
Rely on an access point or base station that:
Act as a bridge between wired and wireless networks
Provide connectivity to existing wired networks
e.g.; Internet
Examples:
Wi-Fi hotspots at airports, offices, homes, etc.
Clients connect to Internet
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

4. Ad Hoc Wireless Networks
Do not rely on fixed infrastructure
No centralized administration
No single point of failure
Nodes are connected directly
Each node functions as both a host and a router
Hence, multi-hop routing is needed sometimes
Each node should be able to:
Detect the presence of other nodes
Identify the corresponding services and attributes
Handle topology changes and malfunctions in nodes
NES540: Wireless Networks Protocols
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Exercise
Work in groups of two or three
Discuss the differences between ad hoc networks and infrastructure-based networks in terms of:
Scalability
Flexibility
Controllability
Routing complexity
8 minutes
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

6. Ad Hoc vs. Infrastructure Nets
Scalability:
In infrastructure networks, more AP’s are added to expand the coverage area and/or to increase the network capacity
In ad hoc networks, it depends on the routing protocol used
Flexibility:
In infrastructure networks, connectivity and mobility are associated with the infrastructure design and coverage
In ad hoc networks, node connectivity and mobility are very flexible as long as there are other nodes within its coverage range
Controllability:
Infrastructure networks are centrally controlled and synchronized
In ad hoc networks, there is no centralized administration. Hence infrastructure networks are more controllable
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

7. Ad Hoc vs. Infrastructure Nets … cont.
Routing Complexity:
In ad hoc network, nodes must act as routers and routing algorithms are needed to route data to the appropriate next hop
This problem does not exist in infrastructure networks as data is routed by the access points via the wired network
Coverage:
In ad hoc networks, coverage is an issue of concern:
The max distance between two neighboring nodes is the max transmission range of the nodes
In infrastructure networks, nodes communicate through AP’s:
The max distance is twice the range of the coverage of a single node
NES540: Wireless Networks Protocols
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Why Ad hoc Networks?
No infrastructure needed
Can be deployed quickly, when no wireless communication infrastructure present
Can act as an extension to existing networks
Adaptive computing and self-configuring
Cost-effective
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

9. Types of Wireless Ad Hoc Networks
There are two types of ad hoc wireless networks:
Fixed ad hoc networks
Mobile ad hoc networks (MANETs)
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

10. Fixed Ad Hoc Wireless Networks
The nodes are stationary
The connections among the nodes are static
Example: Wireless Sensor Networks (WSNs):
Senor nodes collect certain information:
Temperature, humidity, voice, image, etc.
Route data packets to a central base station
The network topology is fixed; unless a node:
Shuts down
Runs out of energy
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

11. Mobile of Ad Hoc Networks (MANETs)
The nodes are mobile
The network topology is dynamic:
Node connectivity may vary with time due to:
The dynamic nature of the wireless medium
Node mobility, departure, new arrival, power outage, etc.
Hence, routing information changes accordingly
Thus, efficient routing protocols are essential
Designing a routing protocols is a challenging task
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

12. Characteristics of MANETs
Distributed operation:
Each node operates independently
No centralized server to manage the network
Limited bandwidth due to:
High bit error rate caused by fading and interference
High packet error rate:
Packet collisions: end-to-end paths are used by several nodes
Long end-to-end delays due to multi-hop routing
Limited energy resource:
Battery operated nodes
Efficient energy consumption is essential
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

13. Characteristics of MANETs … cont.
Security risks:
Portable devices may be stolen
Traffic may insecurely cross wireless links
Eavesdropping, spoofing, & denial of service attacks
Frequent disconnection due to node mobility:
Nodes should adapt to the traffic and transmission conditions according to the nodes’ mobility patterns
Ease and speed of deployment:
No need for infrastructure
No need for administration
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

14. MANETs Classification
Communication-based:
Single-hop
Multi-hop
Topology-based:
Flat
Hierarchical
Aggregate
Node configuration-based:
Homogeneous
Heterogeneous
Coverage area-based:
BAN, PAN, LAN, MAN, and WAN
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

15. Communication-Based Classification
Single-hop:
Simplest type of MANETs
Nodes communicate directly
No intermediate nodes are needed
Nodes do not have to be static
Must stay within range of peer nodes
Power-controlled range
Multi-hop:
Some nodes can’t directly communicate
Relay nodes might be needed for packet delivery
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

16. Topology-based classification
Flat:
All nodes carry the same responsibility and there is no distinction between them
Scalability decreases with the number of nodes
Hierarchical:
Consist of several clusters of nodes
A master node & normal (or slave) nodes
Aggregate:
Network is partitioned into a set of zones
Each node is characterized by two ID’s:
Node ID and zone ID
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

17. Node Configuration-Based Classification
Homogeneous:
All nodes have the same characteristics:
E.g.; hardware configuration (e.g.; CPU, memory, etc.)
Heterogeneous:
Nodes differ in hardware configuration, resources, characteristics, policies, and services.
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

18. Coverage Area-Based Classification
Body Area Networks (BANs)
1-2 m (e.g.; Wearable computers)
Personal Area Networks (PANs)
<10m (e.g.; Bluetooth)
Local Area Networks (LANs)
100m (e.g.; Wi-Fi)
Metropolitan Area Networks (MANs)
50Km (e.g.; WiMAX)
Wide Area Networks (WANs)
??? (e.g.; MBWA)
Driving speed of 250km/h
WiMAX (Worldwide Interoperability for Microwave Access)
MBWA (Mobile Broadband Wireless Access)
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

19. Ad Hoc Networks Applications
Ad hoc networking is gaining importance due to:
The increase of portable devices
The progress in wireless communication
The increasing number of widespread applications
The diversity of applications:
From large-scale, mobile, and highly dynamic networks
To small, static, and power-constrained networks
Ad hoc networking can be applied anywhere at anytime since:
It is flexible and independent on any infrastructure
It allows the devices to maintain connections and be easily added to or removed from the network
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

20. Types of Ad Hoc Network Applications
Public safety and emergency operations:
Search-and-rescue
Police and fire-fighter networks
Military environments:
Soldiers, tanks, planes, etc.
Civilian environments:
Taxi cab network
Meeting and conference rooms
Sports stadiums
Personal area networking:
Smartphone, PAD, laptop, headset, wrist watch, printer, etc.
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

21. Search and Rescue Operations
Medical and rescue service during disasters:
Fast and effective communication
Real-time voice communication
Secure and reliable medical record exchange
Medical teams require fast and effective communications when they rush to a disaster area to treat victims. They cannot afford the time to run cabling and install networking hardware.
The medical team can employ ad hoc networks (mobile nodes) such as laptops and PDAs and can communicate via the wireless link with the hospital and the medical team on-site.
Real-time communication is also important since the voice communication predominates data communication in such scenarios.
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Military Battlefield
Quick and dynamic network setup:
No infrastructure
Highly-mobile (fast topology changes)
Distributed, diverse, and reliable network:
Fast adaptation to mobility and scale
No single point of failure
Secure and efficient communication
Support for multicast routing
Ad hoc networking can be very useful in establishing communication among a group of soldiers for tactical operations and also for the military to take advantage of commonplace network technology to maintain an information network between the soldiers, vehicles, and military information headquarters.
Ad hoc networks also fulfill the requirements of
communication mechanism very quickly because ad hoc network can be set up without planning and infrastructure, which makes it easy for the military troops to communicate with each other via the wireless link.
The other important factor that makes MANET very useful and let it fit in the military base is the fact that the military objects, such as airplanes, tanks, and warships, move at high speeds, and this application requires MANET’s quick and reliable communication.
Because of the information that transfers between the troops, it is very critical that the other side receives secure communication, which can be found through ad hoc networks. At the end, the primary nature of the communication required in a military environment enforced certain important requirements on ad hoc networks, such as reliability, efficiency, secure, and support for multicast routing
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

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MANET Variations
Fully Distributed and Symmetric Environment:
All nodes have identical capabilities and responsibilities
Asymmetric Capabilities:
Different transmission ranges and radio specifications
Different battery lives
Different processing capacity
Different speeds of movement
Asymmetric Responsibilities:
Only some nodes may route packets
Some nodes may act as leaders of nearby nodes (e.g.; cluster head in hierarchical topologies)
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

24. MANET Variations … cont.
Different traffic characteristics:
Bit rate
Timeliness constraints
Reliability requirements
Routing feature (e.g.; broadcast, unicast, multicast, geocast, etc.)
Addressing strategy (e.g.; host-, content-, capability-based, etc.)
May co-exist (and co-operate) with an infrastructure-based network
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad

25. MANET Variations … cont.
Different mobility patterns:
People sitting in a conference room
New York taxi cabs
Kids playing in a park
Military units’ movements
Personal area network
Different mobility characteristics:
Speed
Predictability:
Direction of movement
Pattern of movement
Uniformity (or lack thereof) of mobility characteristics among different nodes
NES540: Wireless Networks Protocols
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MANET Challenges
Limited wireless transmission range
Broadcast nature of the wireless medium
Hidden station problem
Packet loss due to transmission errors
Mobility-induced route changes
Mobility-induced packet losses
Battery constraints
Network lifetime
Potentially frequent network partitions
Ease of snooping on wireless transmissions (security hazard)
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What is Next?
MANET Routing
NES540: Wireless Networks Protocols
Copyright © Dr. Fahed H. Awad