Post on 30-Oct-2014
SRS Document
Caching Strategies Based on Information Density Estimation in
Wireless Ad hoc Networks
ContentsProblem Definition:.....................................................................................................................................1
Existing System:...........................................................................................................................................1
Drawbacks of Existing System:....................................................................................................................2
Proposed System:........................................................................................................................................2
Advantages of proposed system:................................................................................................................2
Important Terms:........................................................................................................................................2
Flowchart for Processing a Query:...............................................................................................................3
Flow chart of processing information messages at user nodes:..................................................................4
The Two Caching Strategies:........................................................................................................................4
Large Sized Caches:.....................................................................................................................................4
Small Sized Caches:......................................................................................................................................5
Modules of the System................................................................................................................................5
Hardware Requirements:............................................................................................................................6
Software Requirements:..............................................................................................................................6
Conclusion:..................................................................................................................................................7
UML Diagrams.............................................................................................................................................7
Use Case Diagram....................................................................................................................................8
Sequence Diagram...................................................................................................................................9
Collaboration Diagram...........................................................................................................................10
Activity Diagram....................................................................................................................................11
Deployment Diagram.............................................................................................................................11
References:................................................................................................................................................12
Problem Definition: Ad hoc networks whose nodes exchange information items in peer-to-peer fashion need
caching strategies to improve performance of content distribution systems.
The problem with existing cashing strategies is that they are computationally expensive. This is the problem to be addressed.
Existing System: Cooperative Caching
Distributed caching strategies such as HybridCache
Vehicular Ad hoc Network
Square Root Rule
Content Discovery
Caching data items in nodes other than neighbors
Caching different content within the neighborhood
Cooperative cache replacement strategy
Caching with Limited Storage Capacity
Cache Replacement Technique
Distributed Caching Strategy
Content Replacement Strategy with LRU technique
Technique based on popularity of content.
Cache replacement technique driven by other factors like access probability, updated frequency and retrieval delay.
Dedicated cache consistency schemes
Data Replication
Eliminating information replicas.
Replication scheme based on convergence time.
Drawbacks of Existing System: Many systems are not suitable for mobile networks.
The existing distributed cache strategies are computationally expensive.
Proposed System: Proposed System introduces a caching strategy for ad hoc networks whose nodes
exchange information items in a peer-to-peer fashion.
It determines cache drop time or content replacement approaches based on the following cache strategies respectively.
Large-sized caches
Small-sized caches
The result is the creation of content diversity within the nodes neighborhood so that a requesting user likely finds the desired information nearby
Advantages of proposed system: Data caching can significantly improve the efficiency of information access in a wireless
ad hoc network by reducing the access latency and bandwidth usage.
Traffic overhead is reduced.
The solving probability of information queries is increased.
Important Terms: Cooperative Caching
It is a process in which all neighborhood nodes involve in making
caching decisions depending on the cache strategy.
Content Diversity
It is a process of eliminating duplicate content in neighbouring nodes and ensuring that the nodes have unique information.
Thus the requesting user likely finds the desired information nearby.
Information Presence Estimation
It is a process of finding information presence within the TTL range of network so that
so that information retrieval is made easy.
Flowchart for Processing a Query:
Flow chart of processing information messages at user nodes:
The Two Caching Strategies: Large Sized Caches
Small Sized Caches
Large Sized Caches:• For this kind of cache a strategy is derived where nodes, independent of each other,
decide whether to cache some content and for how long.
Small Sized Caches: This approach is to design a content replacement strategy that allows nodes to
successfully store newly received information while maintaining the good performance of the content distribution system.
Under both the strategies, each node takes decisions according to its perception of what nearby users may store in their caches and with the aim of differentiating its own cache content from the other nodes’.
Modules of the System The proposed system is logically divided into the following modules.
User Interface
Network Creation and Maintenance
Query Processing
Information Processing
Caching Strategies
Routing Simulation
User Interface Module
This module is responsible to provide required user interface for the entire application. End user interacts with the proposed system through this module.
Network Creation and Maintenance Module
This module is responsible to create nodes and manage them. It allows adding nodes, removing nodes, discovering active nodes etc.
Query Processing
This module is for processing a query. When a query is given by a node, it gets processed based on the caching strategies and their rules and regulations.
Information Processing
This module is responsible to perform activities required when a node receives certain information. It acts upon the information as per the cooperative and distributed caching strategies. It may retain content, replace it and remove it.
Caching Strategies
This module is responsible to model the two caching strategies described and their behavior in the communication process.
Routing Simulation
This module is responsible to simulate the routing process as per the framework of the proposed application.
Hardware Requirements: System : Pentium IV 2.4 GHz.
Hard Disk : 40 GB.
Floppy Drive : 1.44 Mb.
Monitor : 15 VGA Colour.
Mouse : Logitech.
Ram : 512 Mb.
Software Requirements: Operating system : Windows XP.
Coding Language : JAVA
API : Networking
Tool Used : Eclipse
Conclusion: The literature pertaining to the proposed system has been studied.
Then various aspects of the proposed system has been understood conceptually.
Modeling the proposed system has been done using UML diagrams.
UML Diagrams
Use Case Diagram
Discard Dap Query
Search Cache
Discard not to reply query
Forward Query
Discard Solved Query
Cache Chunk
Use Chunk
Discard info with unknown source
Discard Duplicate Info
Discard non reliable info
Forward Info
Discard used chunk
Input Query
Processing Query
<<include>>
User
Processing Information messages
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
<<include>>
Sequence Diagram
: User:GUI :Info
Processing:Query
Processing
query
queryprocess
infoprocess
result
Collaboration Diagram
:GUI
:Info Processing
: User
:Query Processing
3: process
5: process
2: query
6: result
1: query
4: info
Activity Diagram
Input Query
Query Process
Info Process
Cache Updation
Deployment Diagram
Node1 Node2
References: [1] J. Wortham (2009, Sep.). Customers Angered as iPhones Overload AT&T. The New
York Times. [Online]. Available: http://www.nytimes. com/2009/09/03/technology/companies/03att.html
[2] A. Lindgren and P. Hui, “The quest for a killer app for opportunistic and delay-tolerant networks,” in Proc. ACM CHANTS, 2009, pp. 59–66.