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

Copyright © Dr. Fahed H. Awad 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

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

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 Copyright © Dr. Fahed H. Awad

Copyright © Dr. Fahed H. Awad 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

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

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 Copyright © Dr. Fahed H. Awad

Copyright © Dr. Fahed H. Awad 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

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

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

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

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

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

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

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

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

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

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

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

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

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. NES540: Wireless Networks Protocols Copyright © Dr. Fahed H. Awad

Copyright © Dr. Fahed H. Awad 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

Copyright © Dr. Fahed H. Awad 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

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

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 Copyright © Dr. Fahed H. Awad

Copyright © Dr. Fahed H. Awad 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) NES540: Wireless Networks Protocols Copyright © Dr. Fahed H. Awad

Copyright © Dr. Fahed H. Awad What is Next? MANET Routing NES540: Wireless Networks Protocols Copyright © Dr. Fahed H. Awad