WiFi Multi Model Management
Swapna Palaniswamy
Overall Structure
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Introduction
Use Cases
Methods
Results
Other Outcomes
Future Directions
Summary
Introduction to “Serval Mesh”
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A software that can be installed only on the
Android based Smartphones.
Does not depend on any infrastructure.
Creates a Mobile Ad Hoc Network (MANET),
which is also called ” Serval Mesh” that allows
the Smartphones to communicate with each
other.
Previously used only the WiFi Ad-hoc mode to
communicate through the Mesh.
Traditional Cellular System
Serval Mesh
Mutual Intelligibility of WiFi Modes
Client(Cl)
Client(Cl)
Access
Point(AP)
Adhoc(Ah)
Access
Point(AP)
Adhoc(Ah)
During a Disaster
Traditional Cellular System
Serval Mesh
No Cellular Communication
Traditional Cellular System
Serval Mesh
WiFi Multi Model Management
Traditional Cellular System
Serval Mesh
Use Cases
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Base of Pyramid Population: To support poor
population
Disaster and Rescue Purpose: To support any
type of phone i.e., rooted or unrooted.
Remote or Rural Population: To support
population in areas where
1)No cellular network or
2)Marginal cellular coverage
My Research Question
How can we maximise mesh
connectivity among existing and new
models of Android phones given
the lack of Adhoc WiFi support on
Android OS?
Solution to the Problem
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WiFi mode cycling to maintain
connectivity among devices .
Get most WiFi modes out of every
handset especially Adhoc mode.
Challenges: Serval WiFi System
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Android OS does not support Adhoc
Interface
Use of non Scalable “Android WiFi
Tether” code to set the WiFi Adhoc
mode
Android WiFi Tether
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Not Scalable as it is
a single Complex
Script containing
commands for all
the handset models.
Device Centric and
not Chipset Centric.
Edify Script
and
Detection Script
Android WiFi Tether
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Detection of the
chipset was hardwired into java code.
Need to recompile
the code during the
addition of new
phone
Structure of Android WiFi Tether Code
Phone Detection Script
Compiled java
Current WiFi Manager
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Placing of all detection
and commands into
separate files per
chipset type.
Support for previously
unsupported phones
can potentially be
added in the field with
no internet access.
The chipset of the
phone is detected
during the installation
phase.
Detection Script
Edify Script
WiFi Manager
Current WiFi Manager
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The installation may fail due to one of the below
reasons
 The phone supports more than one chipset
 Chipset of the phone is not detected. This is
recorded in the log files. The user can send this
across to the support centre.
Followed by the execution of the corresponding edify
scripts (commands to set up the ad-hoc WiFi
interface) to set up the ad-hoc mode.
The edify scripts are created for each chipset, this
way it is easy to include the script for any new
Android handset introduced in the markets without
even changing the structure of the code.
Analysis of Client Mode
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It is the default mode.
Supported in the Android OS.
It does not require any root access.
Enables even a non rooted phone to
connect to the Serval mesh.
Access Point Mode
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The Android version 2.2 (Froyo) allows the
Smartphones to turn on the Wi-Fi hot spot.
With this application the mobile phone operates in
the Access Point mode and creates a WiFi hot spot
that enables up to eight devices such as mobile
phones, PDAs and laptop to connect to the hot spot.
With the help of this application, it makes it easy to
create Personal Wi-Fi hotspot without making any
major changes in the code.
Therefore, if the mobile has the corresponding
Android version 2.2 then it can potentially support
the Access Point.
Cycling Strategy
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Strategy 1 - Remote Areas with Marginal Coverage
40 seconds- Ad-hoc,
10 seconds- Client,
10 seconds- Access Point.
Strategy 2 - For Uplink/Downlink
10 seconds-Ad-hoc,
40 seconds- Client,
10 seconds- Access Point.
Strategy 3- For Hotspot & Disaster Scenario
10 seconds- Ad-hoc,
10 seconds- Client,
40 seconds- Access Point.
Automatic Cycling of WiFi Modes
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The cycling of WiFi modes is developed to switch
between modes (Client, Access Point, Ad-hoc, off)for
every thirty seconds.
The allocation of thirty seconds for each mode is
implemented for experimental purpose. Currently, it
gives equal opportunity to all the modes. In the
future, depending on the use case the software can
let the user to change the strategy.
Automatic Cycling of WiFi modes
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The timing of this cycling is maintained by setting an
alarm. It checks if there is any peer connected to the
phone for every alarm. If it is, then it will not cycle to
the next potential mode.
Otherwise, it will stop the current mode and start the
next mode.
The current mode is displayed as a label.
The drop down list contains the above mentioned
modes (Client, Access Point, Ad-hoc, Off) depending
on whether the phone is capable of supporting that
particular mode.
Results
Serval mesh in AP mode
Serval mesh in Client mode
Results
Sample Comments from the Android Users
1
“I have installed and made my first call between
zte blade cm7 and T-Mobile pulse mini in less than
a minute. Good work guys”.
2
“An app worthy of praise The aims of the Serval
Mesh project should be supported. Visit the project
website for full info. As Android users tend to be
more tech-minded, I hope people will try the app
and give useful feedback to the devs. For me, I
have it on a Hero and a NexusOne,
communicating, sort of... :)”
Discussions
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The code has been successfully implemented
and tested on Huawei U8150 IDEOS phone.
Feedback is also coming in from various
handsets, as the software has been released
as a prototype to the broader developer
community for testing.
Although the code seems to be highly
successful with the recommended phone, it is
frequently unstable with other Android
phones.
Future Directions
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The Future direction of this project will be analyzing
an efficient Cycling Strategy, which will meet the end
user needs.
Automate the sending of the log files and other
testing data, with deeper user involvement.
The current WiFi Multi Modal Management system
has to be revisited when new modules such as SMS,
Rhizome, Video Streaming, Mapping Service[2] of the
Serval project is been added as they all work
collaboratively.
Other Outcomes
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Have been a co-author for “Serval Mesh
Software – WiFi Multi Model Management”
paper submitted at “ACWR 2011,
International Conference on Wireless
Technologies for Humanitarian Relief”.
Assisted “the Serval Project” team
(www.servalproject.org) to receive a grant of
$40,000 from the Dutch NLnet Foundation.
Summary
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The problems with the previous version
of the “Serval mesh” WiFi system was
analysed
The solutions to those problems were
addressed.
The results was also discussed with
suitable screenshots.