计算机科学论文代写 A Present Technology And Its Trends
Todays Internet is highly successful and it has achieved worldwide adoption. Existing network architectures, communication models and network protocols are sufficient and efficient for the use of the Internet under normal circumstances. However, there are regions and situations where no fixed network infrastructure is available. These networks are frequently partitioned and there is no guarantee of continuous, stable connectivity. Furthermore, networked devices in such environments are often constrained by their transmission range, processing power, storage space, and power supply. In such environments, conventional networking protocols perform poorly, and are often not suitable. To address this issue, number of research initiatives have been undertaken in recent years, primarily under the umbrella of the Delay Tolerant Network Research Group  and a general architecture class called the DTN (Delay Tolerant Network) has been proposed.DTN is also known as opportunistic network, challenged network, extreme network, partitioned network, intermittently connected mobile ad-hoc network. The IC-MANET makes limited assumptions about end-to-end connectivity and peer resources. It utilizes network device mobility, message caching, and relaying techniques to achieve an asynchronous, connected message-oriented communication network.
2.1.1 Characteristics of IC-MANET
There are quite a few definitions of IC-MANET available from the DTNRG  in , the characteristics of a IC-MANET can be summarized as:
A network that has a high level of heterogeneity
A network that suffers from frequent network partitioning
A network that endures recurrent interruption and failures
A network that has asymmetric, long and variable data rates
Devices in a network suffer from energy, bandwidth, storage/memory and cost constraints.
Comparison of IC-MANET with Traditional Network is summarized as under:
Table 2.1 Comparisons of Traditional Network and IC-MANET
It is experienced that applications that require real-time communication and fixed bit-rate transmission are beyond the capability of current IC-MANET implementations, as a reliable route between a source and a destination is always required for the use of such applications. However, applications with different requirements may benefit from the advantages of IC-MANET where constant packet transmission and timely delivery are not essential. The IC-MANET is helpful where there is no fixed network infrastructure or where there is occurrence of frequent partitioning. Typical applications include ad-hoc information discovery and distribution networks; seen in disaster recovery and relief communication, also used in networks like mobile sensor, interplanetary communication, and in military strategy during war-time.
Ad-hoc Information Discovery and Distribution
It is a system where there is a large gathering like ongoing Kumbmela in Allahabad it offers an ideal environment for IC-MANET applications to bridge communication and provide ad-hoc services for social networking. Because in such social locations disruption in communication is highly unavoidable, therefore is possible through the mobility of nodes.
Emergency Rescue / Disaster Management
In rescue operation and disaster management there is always felt inadequacy of communication infrastructure, and here IC-MANETs play a vital role for communication.
Mobile Sensor Networks
This kind of networks are fitted with censor devices with communication capabilities that are distributed over a geographic area to monitor and record motion, chemicals, temperature or their surrounding environment.
As the name suggests the network connection is done through a series of hubs in and around planets, space ships etc., and these hubs provide high-capacity, high-availability Internet traffic over distances that stretch upto hundreds of millions of miles. The Interplanetary Network is classified as a DTN, where information is stored and forwarded to any hub on the system as it always provides connectivity between planets, spacecraft, and the terrestrial Internet.
Communication in Battlefield