Discovery, Personalization and Resource Provisioning of Mobile
Data Provisioning Services for mobile clients
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Transcript of Data Provisioning Services for mobile clients
Data Provisioning Servicesfor mobile clients
byMustafa Ergen
Authors: Mohit Agarwal and Anuj Puri{mohit,anuj}@eecs.berkeley.edu
Berkeley WOW GroupUniversity of California Berkeley
Outline
MotivationProblem DefinitionMain IdeaSystem ArchitectureSoftware ArchitectureApplication Design
Motivation
Cost of downloading data remains high in Wireless Networks Many wireless applications can be designed without need for real time support Stored multimedia (music, video,
presentations) Locality maps (with 3d renderings etc)
Problem Definition
Design a wireless network for mobile clients to access bufferable data
Main Idea
Since data is delay tolerant, it suffices to provide intermittent “bursty” access to the networkIntroduce buffers in the network to exploit The variability in bandwidth Delay tolerance of data
Changes the paradigm from“Anywhere Anytime” connectivity to “Somewhere Sometime” connectivity Infostation Model (First Proposed by Rutgers-
WINLAB)
Interesting Scenarios
Automobile Clients Say a “burst” of 5 seconds every minute
Passengers in Commuter Trains/Buses Route is predictable and large data traffic
make this architecture very suitable
Time
BW
System Architecture
Proxy
Internet /DataBase Server
Mini Base Stations
MobileIntermediate Network
System Architecture
Mini base stations (MBS) placed every mile Freeways, city etc Connect them with backbone network Typical range ~ 100m (radius)
When mobile passes under an MBS, it downloads the data that it needs The whole file is transferred across several MBS
More number of users can be handled pu area (for the same average data rate)
Key Issues
Data Provisioning Protocol Design Interface and functionality of each
layer
Design of applications for such a network Carefully manage varying bandwidth
Data-Management Issues
How to make data available at the MBS when the mobile passes under it Bandwidths on the links feeding the MBS may be
small or the communication delays there may be larger
Mobile may be under an MBS for a short duration
How much data to “push” to which MBSHow is the mobility and bandwidth information shared among different entitiesWe need some intelligence in the network
The need for a Proxy
Proxy acts as an interface to Internet It downloads and stores the file from the DB Avoids connection setup delays involved if
every Infostation were to communicate with the Internet
Runs data management algorithms to exploit bursty link of the mobile. Makes data available at the MBS before
mobile arrives.
Carries out higher layer communication with the mobile
Software Architecture
TL
DPL DPL
MAC
DPL
TL
MAC
Mobile MBS Proxy
APP APP
DB
ProxyAPP
IP
TCP/IP
TL: Transport Layer
End to End functionality between mobile and the proxyConnection SetupAcks for Reliability (if required)PacketizationNo Congestion Control
DPL: Data Provisioning Layer
MBS ProxyMobile
RegistrationRegistrationDereg
Data Data
DPL Contd.
RegistrationRate Control while sending dataMobility predictionBuffering at Proxy: Data that is sent down by TL has to
be be buffered until it is forwarded to correct MBS
MBS: Data that is sent from DPL of Proxy is buffered until it can be delivered to mobile
DPL Contd.
Mobile/Session ID Registered or not MBS/RTT/BW Map/Speed/Direction Next MBS/RTT/BW Data Buffer
Mobile/Session ID Registered or not Proxy’s Address Time Left Data Buffer
Proxy MBS
•Data Structure maintained at DPL
Over all Picture
Mobile requests a file (map / music stream)Default Proxy is the MBS through which the request was madeProxy fetches the file from the DBProxy delivers a segment of this file to the MBS where mobile is registeredAs mobile moves, Proxy “pushes” some part of the file to “next” MBS even before mobile has registered thereMBS buffer the segments and deliver it to the mobile when it passes under its coverage
Application Design
Application may have an alternate (costly, ubiquitous) network like 3G cellular availableIntelligent buffering to reduce the download costs download more in the cheaper mini
base stations
Relationship to Mobile IP
Runs independently of Mobile IPMBS can act as foreign agents also However small burst duration may
not be enough for Mobile IP
Mobile may choose to use either protocols depending on the data required and the network available
Conclusion
We have proposed an architecture for providing cheaper access to wireless dataDesigned the software architecture for this networkWe are currently in the process of implementing this network on a small testbed