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Wireless sensor network

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WSNs, which can be considered as a special case of ad hoc networks with reduced or no mobility, are expected to find increasing deployment in coming years, as they enable reliable monitoring and analysis of unknown and untested environments. These networks are "data centric", i.e., unlike traditional ad hoc networks where data is requested from a specific node, data is requested based on certain attributes such as,"which area has temperature over 35°C or 95°F". Therefore a large number of sensors need to be deployed to accurately reflect the physical attribute in a given area. Routing protocol design for WSNs is heavily influenced by many challenging factors, which must be overcome before efficient communication can be achieved. These challenges can be summarized as follows: A d hoc deployment - Sensor nodes are randomly deployed which requires that the system be able to cope up with the resultant distribution and form connections between the nodes. In addition,...
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Mobile Ad-Hoc Networks.

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a Mobile Ad hoc NETwork (MANET) is one that comes together as needed, not necessarily with any support from the existing infrastructure or any other kind of fixed stations. We can formalize this statement by defining an ad hoc (ad-hoc or adhoc) network as an autonomous system of mobile hosts (MHs) (also serving as routers) connected by wireless links, the union of which forms a communication network modeled in the form of an arbitrary communication graph. This is in contrast to the wellknown single hop cellular network model that supports the needs of wireless communication by installing base stations (BSs) as access points. In these cellular networks, communications between two mobile nodes completely rely on the wired backbone and the fixed BSs. In a MANET, no such infrastructure exists and the network topology may dynamically change in an unpredictable manner since nodes are free to move. Important characteristics of a MANET Characteristics: Dynamic Topologies Nodes are free to mo...
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Data Compression:Storage Space,Coding Requirements and Basic Compression Techniques.

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Data Compression In comparison to the text medium, video frames have high storage requirements . Audio and particularly video pose even greater demands in this regard. The data rates needed to process and send continuous media are also considerable. This chapter thus covers the efficient compression of audio and video . 7.1 Storage Space Uncompressed graphics, audio, and video data require substantial storage capacity, which is not possible in the case of uncompressed video data, even given today’s CD and DVD technology. The same is true for multimedia communications. Data transfer of uncompressed video data over digital networks requires that very high bandwidth be provided for a single point-to-point communication. To be cost-effective and feasible, multimedia systems must use compressed video and audio streams. Most compression methods address the same problems, one at a time or in combi- nation. Most are already available as products. Others are currently under develo...
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