Cooperative Caching for Efficient Dataaccess in Disruption Tolerant Networks

Cooperative Caching for Efficient Dataaccess in Disruption Tolerant Networks

COOPERATIVE CACHING FOR EFFICIENT DATAACCESS IN DISRUPTION TOLERANT NETWORKS

ABSTRACT:

Disruption tolerant networks (DTNs) are characterized by low node density, unpredictable node mobility, and lack of globalnetwork information. Most of current research efforts in DTNs focus on data forwarding, but only limited work has been done onproviding efficient data access to mobile users. In this paper, we propose a novel approach to support cooperative caching in DTNs,which enables the sharing and coordination of cached data among multiple nodes and reduces data access delay. Our basic idea is tointentionally cache data at a set of network central locations (NCLs), which can be easily accessed by other nodes in the network. Wepropose an efficient scheme that ensures appropriate NCL selection based on a probabilistic selection metric and coordinates multiplecaching nodes to optimize the tradeoff between data accessibility and caching overhead. Extensive trace-driven simulations show thatour approach significantly improves data access performance compared to existing schemes.

EXISTING SYSTEM:

Although forwarding schemes have been proposed inDTNs there is limited research on providingefficient data access to mobile users, despite the importance ofdata accessibility in many mobile applications. For example,it is desirable that smartphone users can find interestingdigital content from their nearby peers. In vehicular ad-hocnetworks (VANETs), the availability of live traffic informationwill be beneficial for vehicles to avoid traffic delays.In these applications, data are only requested by mobileusers whenever needed, and requesters do not know datalocations in advance. The destination of data is, hence,unknown when data are generated. This communicationparadigm differs from publish/subscribe systems in which data are forwarded by broker nodes to usersaccordingto their data subscriptions. Appropriate networkdesign is needed to ensure that data can be promptlyaccessed by requesters in such cases.

DISADVANTAGES OF EXISTING SYSTEM:

  • It makes difficult to determine appropriate caching locations forreducing data access delay.
  • It is hard to optimize thetradeoff between data accessibility and caching overhead.

PROBLEM STATEMENT:

DISRUPTION tolerant networks (DTNs) [14] consist ofmobile devices that contact each other opportunistically.Due to the low node density and unpredictable nodemobility, only intermittent network connectivity exists inDTNs, and the subsequent difficulty of maintaining end-toendcommunication links makes it necessary to use “carryand-forward” methods for data transmission.

SCOPE:

The basic idea is to intentionallycache data at a set of network central locations (NCLs).

PROPOSED SYSTEM:

We propose a novel scheme to address the aforementioned challenges and to efficiently support cooperativecaching in DTNs. Our basic idea is to intentionallycache data at a set of network central locations (NCLs),each of which corresponds to a group of mobile nodes beingeasily accessed by other nodes in the network. Each NCL isrepresented by a central node, which has high popularity inthe network and is prioritized for caching data. Due to thelimited caching buffer of central nodes, multiple nodes near a central node may be involved for caching, and we ensurethat popular data are always cached nearer to the centralnodes via dynamic cache replacement based on queryhistory. Our detailed contributions are listed as follows:

  • We develop an efficient approach to NCL selectionin DTNs based on a probabilistic selection metric.The selected NCLs achieve high chances for promptresponse to user queries with low overhead innetwork storage and transmission.
  • We propose a data access scheme to probabilisticallycoordinate multiple caching nodes for responding touser queries. We furthermore optimize the tradeoffbetween data accessibility and caching overhead, tominimize the average number of cached data copiesin the network.
  • Wepropose a utility-based cache replacement schemeto dynamically adjust cache locations based on queryhistory, and our scheme achieves good tradeoffbetween the data accessibility and access delay.

ADVANTAGES OF PROPOSED SYSTEM:

  • Popular data are always cached nearer to the centralnodes via dynamic cache replacement.
  • It is an efficient technique.

SYSTEM CONFIGURATION:-

HARDWARE REQUIREMENTS:-

Processor-Pentium –IV

Speed-1.1 Ghz

RAM-512 MB(min)

Hard Disk-40 GB

Key Board-Standard Windows Keyboard

Mouse-Two or Three Button Mouse

Monitor-LCD/LED

SOFTWARE REQUIREMENTS:

•Operating system:Windows XP

•Coding Language:Java

•Data Base:MySQL

•Tool:Net Beans IDE

REFERENCE:

Wei Gao, Guohong Cao, Arun Iyengar and Mudhakar Srivatsa, “Cooperative Caching for Efficient DataAccess in Disruption Tolerant Networks” IEEE TRANSACTIONS ON MOBILE COMPUTING, VOL. 13, NO. 3, MARCH 2014

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