This document proposes an anti-disaster communication system using smartphones and Wi-Fi networks. The system aims to spread data in disaster areas by using Wi-Fi Direct between mobile devices. It will check directions to determine if data should be spread based on the sender and receiver's positions and the base direction. Data will be spread along with metadata and direction information. The implementation aims to balance battery, network, and storage usage against reaching affected areas. It compares to related epidemic routing and spray-and-wait approaches. The system checks directions using latitude, longitude, and vector calculations to determine if data should be accepted or not.

1. Anti-disaster communication
system based on smartphone and
Wi-Fi network
Group : 1
Author : Kazuhiro Matsumoto
Supervisor : Prof. Zixue Cheng

2. Agenda
• Introduction
• Model
• System(Model)
• Wi-Fi network with portable
commutation devices
• Spread Data
• Implementation/evaluation
• Conclusion/Future Work

3. Introduction
• Background
• Development of wireless network
• Development of Mobile device
• Natural Disaster
• Purpose
• Build a network which is consists of Wi-Fi Direct and
mobile devices
• Spread Data into the network
• Issue
• How to spread the data
• How to save the resources on the network
• Solution
• Spread data with GPS data
• Spread data with meta data of the Data

4. Model
Direction Check :
Far from previous Node
Close to Base Direction
Disaster area
Original
Sender
Node
Message
Spreading
Base Direction

5. Related Researches
Battery Use Network Use Storage use Reaching
ability
[2] △ △ △ ◎
[5] ◎ ◎ ◎ △
[3] △ ○ ○ ○
[4]Our system
[2] Place replica epidemically : duplicate on all nodes
[5] Spray and wait : spread data around sender once and wait until one of the
node come close to the target node
[3] Predict the position and place replica

6. System/Methods
Smart Phone/ Tablet
User Input : Message
Direction Check.
GPS
Save Show
Message Message
Create Message :
Add metadata
Add Direction Info.
Wi-Fi Direct :
Communicate with other Smart Phones/ Tablets

7. Direction Check Method 1
Sender position : (Sender Latitude, Sender Longitude)
My position : (My Latitude, My Longitude)
Base Directions(vector) :
My Direction(Vector) :
((My Latitude)-(Sender Latitude), (My Longitude)-(Sender Longitude))
Direction Check
If (Base Direction * My Direction > xxx ) accept
Else do nothing

8. References
[1] Hideya Ochiai and Hiroshi Esaki, “Topology Change Tolerant Routing for Delay
Tolerant Network”, 情報処理学会論文誌 50(9) page 2312-2326, Sept 2009
[2] Amin Vahdat and David Becker, “ Epidemic Routing for Partially-Connected Ad
Hoc Network”, Tech. Rep. CS-2000006, Duke University, April 2000
[3] Hirofumi Ueda and Norihito Fujita, “Replica Placement using Node Distribution
Estimation in Delay-Tolerant Network”, 電子情報通信学会技術研究報告. IN, 情報ネッ
トワーク 109(37) page 49-54, May 2009
[4] Sun Weihua, Tomoya Kitani, Naoki Shibata, Keiichi Yasumoto, “A Data Gathering
and Sharing Proposal for Disaster Relief based on DTN”,情報処理学会研究報告.
CSEC, [コンピュータセキュリティ] 2009(20), 61-66, 2009-02-26

9. Thank you for listening