AD HOC NETWORKS BY: Bhagyashree Fulzele 03 Sneha Ghosh 23 Yamini Kothe 27 Namrata Nitnawre 12

Wireless AD HOC network  A wireless ad hoc network is a decentralized wireless network  The network is ad hoc because it does not rely on a preexisting infrastructure, such as routers in wired networks or access points in managed (infrastructure) wireless networks.  Instead, each node participates in routing by forwarding data for other nodes, and so the determination of which nodes forward data is made dynamically based on the network connectivity.

Application of Wireless AD HOC Networks The decentralized nature of wireless ad hoc networks makes them suitable for a variety of applications where central nodes can't be relied on, and may improve the scalability of wireless ad hoc networks compared to wireless managed networks, though theoretical and practical limits to the overall capacity of such networks have been identified. Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like natural disasters or military conflicts. The presence of a dynamic and adaptive routing protocol will enable ad hoc networks to be formed quickly.

Technical requirements  An adhoc network is made up of multiple “nodes” connected by “links”.  Links are influenced by the node's resources (e.g. available energy supply, transmitter power, computing power and memory) and by behavioral properties (reliability, and trustworthiness), as well as by link properties (e.g. line-of-sight interference, length-of-link and signal loss, interference and noise).  Since new and old links can be connected or disconnected at any time, a functioning network must be able to cope with this dynamic restructuring, preferably in a way that is timely, efficient, reliable, robust and scalable.

Technical requirements conti….  The network must allow any two nodes to communicate, often via other nodes that relay the information. A “path” is a series of links that connects two nodes.  Often there are multiple paths between any two nodes. Nodes are often limited by transmitter power (transmission range) and available energy resources. Transmitter power often consumes the most energy in the node.

Wireless ad hoc networks can be further classified by their application: Mobile AD HOC Networks (MANETs) Wireless Mesh Networks Wireless Sensor Networks

1.Mobile AD HOC Networks  A mobile ad hoc network (MANET), sometimes called a mobile mesh network, is a self-configuring network of mobile devices connected by wireless links.  Each device in a MANET is free to move independently in any direction, and will therefore change its links to other devices frequently.  Each must forward traffic unrelated to its own use, and therefore be a router.  The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route traffic.

 Such networks may operate by themselves or may be connected to the larger Internet.  MANETs are a kind of wireless ad hoc networks that usually has a routable networking environment on top of a Link Layer ad hoc network.

Types of MANET  Vehicular Ad Hoc Networks (VANETs)  Intelligent vehicular ad hoc networks (InVANETs)  Internet Based Mobile Ad hoc Networks (iMANET)

 Intelligent vehicular ad hoc Networks: Intelligent vehicular ad hoc networks (InVANETs) are a kind of artificial intelligence that helps vehicles to behave in intelligent manners during vehicle-to-vehicle collisions, accidents, drunken driving etc.  Internet Based Mobile Ad hoc Networks: Internet Based Mobile Ad hoc Networks (iMANET) are ad hoc networks that link mobile nodes and fixed Internet-gateway nodes. In such type of networks normal ad hoc routing algorithms don't apply directly.  Vehicular Ad Hoc Networks :Vehicular Ad Hoc Networks (VANETs) are used for communication among vehicles and between vehicles and roadside equipment.

2.Wireless mesh network o A wireless mesh network (WMN) is a communication network made up of radio nodes organized in a mesh topology. o Wireless mesh networks often consist of mesh clients, mesh routers and gateways. o The mesh clients are often laptops, cell phones and other wireless devices while the mesh routers forward traffic to and from the gateways which may but need not connect to the Internet.

Wireless mesh network conti…. o The coverage area of the radio nodes working as a single network is sometimes called a mesh cloud. o Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network. o A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest of the nodes can still communicate with each other, directly or through one or more intermediate nodes

Architecture o Wireless mesh architecture is a first step towards providing cost effective and dynamic high-bandwidth networks over a specific coverage area. o Wireless mesh architectures infrastructure is, in effect, a router network minus the cabling between nodes. It's built of peer radio devices that don't have to be cabled to a wired port like traditional WLAN access points (AP) do. o Mesh architecture sustains signal strength by breaking long distances into a series of shorter hops. o Intermediate nodes not only boost the signal, but cooperatively make forwarding decisions based on their knowledge of the network, i.e. perform routing. o Such an architecture may with careful design provide high bandwidth, spectral efficiency, and economic advantage over the coverage area.

Example of three types of wireless mesh network: Infrastructure wireless mesh networks: Mesh routers form an infrastructure for clients. Client wireless mesh networks: Client nodes constitute the actual network to perform routing and configuration functionalities. Hybrid wireless mesh networks: Mesh clients can perform mesh functions with other mesh clients as well as accessing the network.

Operation o The principle is similar to the way packets travel around the wired Internet — data will hop from one device to another until it reaches its destination. o Dynamic routing algorithms implemented in each device allow this to happen. o To implement such dynamic routing protocols, each device needs to communicate routing information to other devices in the network. o Each device then determines what to do with the data it receives — either pass it on to the next device or keep it, depending on the protocol. o The routing algorithm used should attempt to always ensure that the data takes the most appropriate (fastest) route to its destination.

Applications Some current applications: o U.S. military forces are now using wireless mesh networking to connect their computers, mainly ruggedized laptops, in field operations. It enables troops to know the locations and status of every soldier or marine, and to coordinate their activities without much direction from central command. o Electric meters now being deployed on residences transfer their readings from one to another and eventually to the central office for billing without the need for human meter readers or the need to connect the meters with cables. o The laptops in the one laptop per child program use wireless mesh networking to enable students to exchange files and get on the Internet even though they lack wired or cell phone or other physical connections in their area. o Calls between two satellite phones are routed through the mesh, from one satellite to another across the constellation, without having to go through an earth station.

3.Wireless sensor network  A Wireless Sensor Network (WSN) consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location.  The more modern networks are bi- directional, enabling also to control the activity of the sensors.  The development of wireless sensor networks was motivated by military applications such as battlefield surveillance; today such networks are used in many industrial and civilian application areas, including industrial process monitoring and control, machine health monitoring, environment and habitat monitoring, healthcare applications, home automation, and traffic control.

Characteristics  Unique characteristics of a WSN include:  Limited power they can harvest or store  Ability to withstand harsh environmental conditions  Ability to cope with node failures  Coping with mobility of nodes  Dynamic network topology  Communication failures  Heterogeneity of nodes  Large scale of deployment  Unattended operation  Node capacity is scalable, only limited by bandwidth of gateway node.

Applications  Area monitoring Area monitoring is a common application of WSNs. In area monitoring, the WSN is deployed over a region where some phenomenon is to be monitored. For example, a large quantity of sensor nodes could be deployed over a battlefield to detect enemy intrusion.  Greenhouse monitoring Wireless sensor networks are also used to control the temperature and humidity levels inside commercial greenhouses.  Landslide detection A landslide detection system, makes use of a wireless sensor network to detect the slight movements of soil and changes in various parameters that may occur before or during a landslide.  Landfill ground well level monitoring and pump counter Wireless sensor networks can be used to measure and monitor the water levels within all ground wells in the landfill site and monitor accumulation and removal.

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