S-38.3310 Thesis Seminar on Networking Technology
Design and Implementation of
Mobile Peer-to-Peer Application
Juuso Lehtinen
juuso@netlab.hut.fi
Thesis written at Networking Laboratory,
Department of Electrical and Communications Engineering,
Helsinki University of Technology
Author: Juuso Lehtinen
Supervisor: Prof. Raimo Kantola
Instructor: Nicklas Beijar, Lic.Tech.
Agenda
 Introduction
 The Problem
 Objectives
 Research Questions
 Methodology
 Background
 Client-Server Architecture
 Peer-to-Peer Architectures
 Mobile Peer-to-Peer Application
 Requirements for Mobile Peer-to-Peer
 Design and Implementation
 Measurements
 Conclusions
 Further Research Possibilities
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Introduction
Today, 60-80% of all Internet traffic is peerto-peer
Services seen traditionally only in the fixed
networks are becoming available in the
mobile networks too as the mobile
terminals get more powerful
Users want to be able to share content on
their mobile phones regardless place or
time
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The Problem – User Perspective
No convenient way to share information
between phones
The content must be uploaded to be available,
even though there is no knowledge if anyone
will ever download it
Search for the content must be done manually if
the location of the content is not known in
advance
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The Problem – Operator Perspective
Operator has to maintain a centralized
server which holds the content
The storage server costs money, is a single
point of failure, and has hard time dealing with
the flash crowd phenomenon
Possible revenues are lost because the
operator is not able to provide users effective
way to share content
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Objectives (1/2)
 The objective of the thesis is to find out how to
efficiently realize a peer-to-peer file sharing
application for mobile phone networks and
effectively allow users to share and acquire
content which is saved in their and their friends’
mobile phones
 The software has to be efficient on resource
usage, both on those of the handset and the
network, and use the already existing (and
upcoming) network infrastructure as much as
possible to allow easy development and
deployment
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Objectives (2/2)
The Session Initiation Protocol (SIP) is
used as the underlying signaling protocol
Use of SIP allows easy integration with the
future IMS networks
Charging and billing for the application can be
easily implemented in the SIP-aware core
network
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Research Questions
Does a modern mobile phone have
enough resources to run the peer-to-peer
application?
Is SIP a suitable protocol for peer-to-peer
signaling?
Is the software performance satisfying in
user perspective?
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Methodology
Literature study
Comparison of different peer-to-peer
architectures
Special needs for peer-to-peer imposed by
mobile environment
Design and Implementation of mobile
peer-to-peer application
Performance measurements
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Agenda
 Introduction
 The Problem
 Objectives
 Research Questions
 Methodology
 Background
 Client-Server Architecture
 Peer-to-Peer Architectures
 Mobile Peer-to-Peer Application
 Requirements for Mobile Peer-to-Peer
 Design and Implementation
 Measurements
 Conclusions
 Further Research Possibilities
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Client-Server Architecture
 One high-performance
server holds all the
content in the network
Owner of the server has
full control on the
shared content
 Multiple clients share
content via the
centralized server
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Peer-to-Peer Architectures
Unstructured peer-to-peer architectures
Centralized architecture
Decentralized architecture
Hybrid architecture
Structured peer-to-peer architectures
Based on DHT-algorithm
Wildcard searches are not possible
Exact name or hash for the searched content must
be known
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Centralized Peer-to-Peer Architecture
 A centralized server, or a
cluster of servers holds
information about the files
available on the clients
 Owner of the server has
high control on content
 The clients transfer content
directly without the server
involvement
 The server is used only for
content searches
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Decentralized Peer-to-Peer Architecture
 All nodes are equal in
the network – There is
no centralization
No single node has
control over the content
shared by the other users
 Searches are done by
flooding search
requests in the network
 Downloads are
executed in peer-topeer fashion
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Hybrid Peer-to-Peer Architecture
 Ordinary clients are connected
to super-peers as in centralized
peer-to-peer architecture
 A super-peer has high control on
content shared by ordinary nodes
connected to it
 Super-peers are connected to
each other in decentralized
manner
 Super-peers do not have control
on content announced by the other
super-peers
 Downloads are executed in
peer-to-peer fashion
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Agenda
 Introduction
 The Problem
 Objectives
 Research Questions
 Methodology
 Background
 Client-Server Architecture
 Peer-to-Peer Architectures
 Mobile Peer-to-Peer Application
 Requirements for Mobile Peer-to-Peer
 Design and Implementation
 Measurements
 Conclusions
 Further Research Possibilities
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Requirements for Mobile Peer-to-Peer (1/2)
Technical Constraints
Memory size
CPU performance
Screen and keyboard size
Battery capacity
Access Network Parameters
Limited bandwidth shared between multiple users in
the same cell
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Requirements for Mobile Peer-to-Peer (2/2)
 Special Needs of Mobile Environment
Support for various access networks
Operator control
Feasible bandwidth pricing
 User Requirements
Quick response times
Rapid downloads
Group management features for sharing private content
 Lot of content is probably self-created, like pictures/videos
taken with camera-phone
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Optimal Architecture
Hybrid architecture optimal for mobile use
Minimizes signaling load on the air interface
Allows operator to have control on content by
controlling the super-peer
Multiple operators can network super-peers in
peer-to-peer fashion still retaining quite high
autonomy
Super-peer can be also operated by private
entity, e.g. family or sports club
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Design and Implementation of MP2P
Hybrid peer-to-peer architecture was
chosen for implementation
Software was implemented in C++ on
Nokia Series 60 Platform
SIP functionality is provided by phone’s
built-in SIP-stack
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Implementation
 Software is designed
to be modular so it
can be easily
enhanced
Client consists of four
modules: Finder,
Register, Transfer, and
Graphical User Interface
Chatting and streaming
modules are to be
implemented in near
future
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SIP Requests Used for Peer-to-Peer
Signaling
INVITE – Content search and download
session establishment
MESSAGE – File-list updates to superpeers
Search and file-list update messages have
all content information encoded in XML to
enable easy parsing and extension of the
format in the future
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Use Case – Search and Download
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Measurements
 Both signaling delays, and file transfer
bandwidth were measured
All measurements were conducted in 3G/WCDMA
network
 Search delays were measured to be under
700ms in most of the cases
 Signaling delays for download session set-ups
were measured to be under 1.5s
 File transfer speeds were around 11kB/s
This is restricted by the available upstream bandwidth in
the mobile network (upstream 128kbit/s, downstream:
384kbit/s)
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Agenda
 Introduction
 The Problem
 Objectives
 Research Questions
 Methodology
 Background
 Client-Server Architecture
 Peer-to-Peer Architectures
 Mobile Peer-to-Peer Application
 Requirements for Mobile Peer-to-Peer
 Design and Implementation
 Measurements
 Conclusions
 Further Research Possibilities
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Conclusions
 The working prototype application proves that
peer-to-peer file sharing can be implemented on
mobile platform
 The user perceived performance of the
application is close to the performance seen in
applications in fixed networks
 The SIP signaling is suitable for mobile peer-topeer use. The protocol overhead is not a
problem in the modern cellular networks.
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Further Research Possibilities
Grouping / clustering mechanisms for
peer-to-peer content sharing
Caching of popular files into the fixed
network to reduce load on the air interface
Trust, reputation, accountability, security,
and interoperability issues in the mobile
peer-to-peer context
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Thanks for patience!
Questions?
Contact: juuso@netlab.hut.fi
References:
1.
2.
M. Matuszewski, N. Beijar, J. Lehtinen and T. Hyyryläinen, Mobile Peer-to-Peer Content Sharing
Application, in IEEE Consumer Communications and Networking Conference, CCNC2006, 2006, Las
Vegas, Nevada, USA
N. Beijar, M. Matuszewski, J. Lehtinen and T. Hyyryläinen, Mobile Peer-to-Peer Content Sharing
Services in IMS, in The International Conference on Telecommunication Systems, Modeling and Analysis
2005, ICTSM2005, 2005, Dallas, Texas, USA
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