Introduction to MANET and Clustering in MANET

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Chapter 3: Applications of MANET:

With the increase of use portable devices as well as progress in wireless communication, ad hoc networking is gaining importance. Ad hoc networking can be applied anywhere, where there is no communication infrastructure or the existing infrastructure is expensive or difficult to implement. Ad hoc networking allows the devices to maintain links to the network as well as easily adding as well as removing devices to and from the network. The set of applications for MANETs is diverse, ranging from large-scale, mobile, highly dynamic networks, to small, static networks that are constrained by power sources. Besides the inheritance applications that move from traditional infrastructure environment into the ad hoc context, a great deal of new services can and will be generated for the new environment. Typical applications include:

3.1 Defense (Military battlefield applications):

In modern battlefield requires robust and reliable (secure) communication military battlefield in many forms. Most communicating nodes are installed in mobile vehicles used for defense. Defense personnel could carry telecomm devices that could talk to a wireless base station or directly to other telecom devices if they are within the radio range. However these forms of communication are considered to be primitive. At times when wireless base station is destroyed by enemy, a soldier will be prohibited from communicating with other soldiers if the called party is not within the radio range. This is the scenario where mobile ad hoc networks come into play. Ad hoc networks are well known as self organizing networks since they are robust when nodes disappear due to destruction or mobility. Through multi hop communication soldiers can communicate to remote soldiers via data hoping and data forwarding from one radio device to another.
3.2 Sensor Networks:

Another application of MANETs is sensor networks. This technology is a network composed of a very large number of small sensors. These can be used to detect any number of properties of an area. Examples include temperature, pressure, toxins, pollutions, etc. Applications are the measurement of ground humidity for agriculture, forecast of earthquakes. The capabilities of each sensor are very limited, and each must rely on others in order to forward data to a central computer. Individual sensors are limited in their computing capability and are prone to failure and loss. Mobile ad hoc sensor networks could be the key to future homeland security.
3.3 Automotive Applications:

Automotive networks are widely discussed currently. Cars should be enabled to talk to the road, to traffic lights, and to each other, forming ad-hoc networks of various sizes. The network will provide the drivers with information about road conditions, congestions, and accident-ahead warnings, helping to optimize traffic flow.
3.4 Commercial Sector:

Ad hoc network can be used in emergency/rescue operations for disaster relief efforts, e.g. in flood, fire, earthquake. Emergency rescue operations must take place in case of nonexistent and damaged communications infrastructure and rapid deployment of a communication network is required. Information is relayed from one rescue team member to another over a small handheld device with portability. Other commercial scenarios include e.g. ship to ship ad hoc communication, enforcement of law etc.
3.5 Personal Area Network:

Personal Area Networks (PANs) are formed between various mobile and fixed nodes in an ad-hoc manner, e.g. for creating a small network. Nodes can form an autonomous network, interconnecting various devices. PANs becomes more meaningful when connected to a larger private or public network.
3.6 Conferencing:

Mobile Conferencing one of the most recognized application. Set up of an Ad Hoc network is essential for mobile users where they need to gather in a project outside the office environment in an ad hoc manner.
3.7 Embedded Computing Application:

Computing internetworking machines offer flexible and efficient ways of establishing communication methods with the help of ad hoc networking.
Chapter 4: Issues and Challenges of MANET:
4.1 Quality of service (QoS):

The parameters of performance level of services are known as QoS. Different applications have different QoS requirement. These QoS parameters may be computes on per link, per flow, per node basis. Delay, jitter, packer loss rate, bit error rate, bandwidth are some of the QoS parameters in MANET.
4.2 Routing:

Routing is a crucial issue in MANET. The conventional routing protocols used on wired networks do not perform satisfactory in MANET, which has basic characteristics of mobility and rapid membership change. In Ad Hoc networks, we need new routing protocols for following reasons:

i) The mobility resulting change of topology of the network which may be dynamic in nature.
Ii) Existing protocols show least desirable behavior when presented with a highly dynamic and frequent changing interconnection topology.
Existing routing protocols face heavy a computational load on each mobile computing device for the issues of processing power consumption and memory size.
Existing routing protocols are not designed for dynamic and self-starting behavior as required to utilize Ad-Hoc networks.
Existing routing protocols for example, Distance Vector Protocol take a lot of time for convergence upon the failure of a link, which is very frequent in Ad Hoc networks. Existing routing protocols suffer from looping problems either short lived or long lived. Methods adopted to solve the problem of looping in traditional routing protocols may not be applicable to Ad Hoc networks.
4.3 Spectrum allocation:

The problem of device mobility, interference, limited range, limited data throughput and sharing of the Radio Frequency spectrum amongst devices are various crucial issues. Most experimental Ad hoc networks are based on the ISM band. To prevent the problem of interference, Ad hoc networks must operate over some form of specified spectrum range. Microwave ovens operate in 2.4 GHz ISM band, which may interfere with wireless LAN systems.
4.4 Energy Efficiency:

Energy Efficiency is a concern in MANET. Most existing protocols do not pay attention of power consumption. However mobile devices today mostly operated by batteries. Battery technology is still lagging behind the microprocessor technology. The lifetime of a Li-on battery is very low.
4.5 Security and Privacy:

Wireless links in an ad hoc network vulnerable to various link attacks like message replay, message distortion, passive eavesdropping, active impersonation. Eavesdropping may cause access to secret information, violating confidentiality. Active attacks may cause injection of erroneous messages, modification of messages, delete of messages and to impersonate a node. As a result, creating problem of integrity, authenticity and availability.