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Challenges of MANETs

A Manet environment has to overcome certain issues of limitation and inefficiency. It includes: ·          The wireless link characteristics are time-varying in nature: There are transmission impediments like fading, path loss, blockage and interference that adds to the susceptible behavior of  wireless channels. The reliability of wireless transmission is resisted by different factors. ·          Limited range of wireless transmission – The limited radio band results in reduced data rates compared to the wireless networks. Hence optimal usage of bandwidth is necessary by keeping low overhead as possible. ·          Packet losses due to errors in transmission – MANETs experience higher packet loss due to factors such as hidden terminals that results in collisions, wireless channel issues (high bit error rate (BER)), interference, and frequent breakage in paths caused by mobility of nodes, increased collisions due to the presence of hidden terminals and uni-directional links. ·
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Characteristics of MANETs

·      In MANET, each node act as both host and router. That is it is autonomous in behavior.  ·      Multi-hop radio relaying- When a source node and destination node for a message is out of the radio range, the MANETs are capable of multi-hop routing. ·      Distributed nature of operation for security, routing and host configuration. A centralized firewall is absent here. ·      The nodes can join or leave the network anytime, making the network topology dynamic in nature. ·      Mobile nodes are characterized with less memory, power and light weight features. ·      The reliability, efficiency, stability and capacity of wireless links are often inferior when compared with wired links. This shows the fluctuating link bandwidth of wireless links. ·      Mobile and spontaneous behavior which demands minimum human intervention to configure the network. ·      All nodes have identical features with similar responsibilities and capabilities and hence it forms a completely symm
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Types of MANETs

There are different types of MANETs including:         InVANETs – Intelligent vehicular ad hoc networks make use of artificial intelligence to tackle unexpected situations like vehicle collision and accidents.           Vehicular ad hoc networks (VANETs) – Enables effective communication with another vehicle or helps to communicate with roadside equipments.           Internet Based Mobile Ad hoc Networks (iMANET) – helps to link fixed as well as mobile nodes.
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What is a MANETs

It is an infrastructure less IP based network of mobile and wireless machine nodes connected with radio. In operation, the nodes of a MANET do not have a centralized administration mechanism. It is known for its routable network properties where each node act as a “router” to forward the traffic to other specified node in the network.
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Data Dissemination Broadcast-disk Models

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Data Dissemination Broadcast-disk Models: ·          Presumed that all the n records to be broadcast are stored on a circular disk from 0° to 360° ·          A hypothetical disk revolves and the angle changes from 0°to 360° ·          The entire N bits in n records get pushed through a hypothetical reading-head over the disk. ·          The head continuously reads each bit of a record just beneath it and broadcasts it instantaneously on the wireless network ·          During next revolution each bit in the records positioned from 0° to 360° broadcast once again in the same sequence as in earlier revolution Number of adaptations and algorithms for broadcast: 1. Circular Multi-disk Model 2. Flat Disk Model 3. Multi-disk Model with repetition rate proportional to priority 4. Skewed disk model Circular multi-disk model • Each block of records pushed with a repetition rate proportional to its hierarchical level Each rotating disk cycle:
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Classification of Data-Delivery Mechanisms in mobile computing

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Data Dissemination and Broadcasting Systems: Classification of Data-Delivery Mechanisms: ·          Push-based mechanisms (publish–subscribe mode) ·          Pull-based mechanisms (on-demand mode) ·          Hybrid mechanisms (hybrid mod                        Push-based Mechanisms: ·          Server pushes data records from a set of distributed computing systems ·          Examples of distributed computing systems advertisers or generators of traffic congestion, weather reports, stock quotes, and news report A server or computing system pushing the data records from a set of distributed systems : Publish–subscribe mode • In which the data pushed as per the subscription for a push service by a user Pushing Algorithm: Select a structure of data records to be pushed • An algorithm provides an adaptable multi-level mechanism that permits data items to be pushed uniformly or none uniformly after structuring them according to their relative impor
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Client Server Computing with Adaptation

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Client Server Computing with Adaptation • Two adapters (adaptation software) at a mobile device • An adapter for standard data format for synchronization at the mobile-device • Another adapter for the backend database copy, which is in a different data format for the API at the mobile-device Adaptation: Software to get data in one format or data governed by one protocol and convert it to another format or to data governed by another protocol ·          Used for interchange between standard data formats and data formats for the API ·          IBM WebSphere Everyplace Access (WEA) provides adapters for synchronization objects (for example, XML format synchronization objects) and the objects of API databases (for example, for the PIM APIs)
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