Context-Aware Resource Management for Mobile Servers

C. Ververidis, E.C. Efstathiou, S. Soursos

and G.C. Polyzos

Mobile Multimedia LaboratoryDepartment of Computer Science

Athens University of Economics and Business

10434 Athens, Greece

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Outline

Technology Trends Location-Based Services The Service Provision Environment Network Architecture Implementation Mechanisms

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Technology Trends

Computing and Telecommunication technologies convergence– From the WWW to the Mobile Web– Need for anytime anywhere access to information

Abundant access bandwidth, storage, and processing power at the edges of the network– Emergence of low-cost wireless access technologies, e.g.

• IEEE 802.11• Bluetooth

– Emergence of Peer-to-Peer (P2P) service models “Next-generation” terminals

– Small devices with server-like features and capabilities

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Location-Based Services (LBS)

Mobile Web and LBS are evolving together The Case for LBS

– Innovative, useful services• attract new customers

• enhance customer loyalty to the provider

– Revenue increase due to traffic generated by the use of such services

Traditional business models for LBS vary depending on the number of participants in the LBS value chain

LEVEL OF LBS REVENUE SHARING

Mobile operator provides connectivity, positioning

and content

Mobile operator provides connectivity. Positioning

and content are provided by external providers

Min Max

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New LBS Model

Mobile Operator provides– Connectivity– Positioning Technologies– Service Advertisement & Discovery Infrastructure

Mobile Subscribers provide– Content, possibly sensitive to time and space

changes Operator’s network externalities depend

heavily on customers’ content

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Service Provision Environment

Wireless Access Provider (WLAN or UMTS)– Access Point (AP) or Base Station (BS) covering an area

of interest Some Mobile Subscribers can act as servers and

offer content– Mobile devices with attached digital cameras

Content sensitive to place and time– e.g. photo-series or low length/quality videos that provide

information on the traffic conditions in the coverage area Content available only in the specific coverage area

– No value outside due to space and time sensitivity and the high costs of transferring it

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Assumptions

Network operator has the infrastructure for Service Advertisement and Discovery– Centralized or de-centralized

Network operator possesses a positioning technology– From COO and OTDOA-IDL to GPS– We use a simple approach based on SINR values

measured from the AP

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Example: Traffic Conditions

AP

Message from M1

Each mobile server– with the appropriate equipment

(e.g. photo camera)– can offer (to other mobile

subscribers) traffic condition information (including photos or short videos)

The service is only available within the AP’s coverage area

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Environment Set-up

AP

AP

AP AP

Single AP Coverage area spreads

along a main traffic road Subscribers are informed

about the traffic condition of the specific road

Extension: Multiple APs Covering and providing

traffic information for many roads

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Architecture’s Goals

Give the mobile server the appropriate uplink bandwidth to serve the requests

Provide the mobile subscribers/clients the appropriate transfer rate according to their relative position to the mobile server

Keep the content inside the coverage area by favoring content exchanges between mobile servers

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Architecture

Differentiate uplink rates for each server-client pair and according to their relative position

UMTS:– At the Radio Resource Management (RRM) located at the

Radio Network Controller (RNC) IEEE 802.11 WLANs:

– Software upgrades at the Access Point to support advanced queuing disciplines (other than FIFO)

Mobile Server Mobile Client

Inner Circle

Middle Circle

Outer Circle

Inner Circle 10kbps 10kbps 20kbps

Middle Circle 10kbps 20kbps 50kbps

Outer Circle 20kbps 20kbps 50kbps

AP

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Implementation

Need for a QoS context-aware scheme Two approaches:

– LBS-DF• Based on IETF Differentiated Services

– LBS-IS• Based on IETF Integrated Services

Different implementation for each technology– UMTS vs. IEEE 802.11 WLAN

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LBS-DF Approach

We define 3 QoS classes (from 1 to 3) – Class 3 is the class with the higher priority– Different transmission rates for each class

3 flow-serving queues at AP with different serving rates Extra packets are dropped or treated as in Assured Service

class AP changes the QoS class according to the power readings

and transparently to the mobile userMobile Server Mobile Client

Inner CircleMiddle Circle

Outer Circle

Inner CircleQoS Class

1QoS Class 1

QoS Class 2

Middle CircleQoS Class

1QoS Class 2

QoS Class 3

Outer CircleQoS Class

2QoS Class 2

QoS Class 3

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LBS-IS Approach

Several queues at AP, each serving a flow for a mobile server – client session

A “Scheduler” module keeps an NxM array– N: number of mobile servers– M: number of mobile subscribers

CAC in order not to exceed total available bandwidth– ~5 Mbps for 802.11 WLANs and 2 Mbps for UMTS

Goal:– Maximize the number of

completed file transfers

Mobile Clients Mobile Servers

A B C D

A X10kbp

s50kbp

s20kbps

C 10kbps30kbp

sX 50kbps

D100kbp

s20kbp

s40kbp

sX

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UMTS Issues

Throughput that a mobile server has on the uplink is based on the chip rate received from the BS

Differentiating the chip rate differentiating the transmission rate

Proposed QoS classes are different from the UMTS QoS classes– UMTS QoS classes: generic QoS, same for all

traffic in our service environment– Proposed QoS classes: lower-level QoS

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IEEE 802.11 WLAN Issues

Upcoming 802.11e standard:– A new MAC layer algorithm (Hybrid Coordination

Function – HFC)– WLAN AP acts as a point coordinator and polls

mobile stations for data, similar to the UMTS mechanism

– Use of CF-Poll messages in HFC:• Expected start time of transmission• Maximum duration of transmission

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Summary

New mobile technologies and LBS are forming a new business model for service provision

Mobile Servers offering content sensitive to place and time changes

Network architecture with the AP configuring mobile server’s uplink bandwidth– DiffServ vs. IntServ approach– UMTS vs. IEEE 802.11 WLANs

Thank you!

C. Ververidis, E.C. Efstathiou, S. Soursos and G.C. Polyzos

Mobile Multimedia Laboratory

Department of Computer Science

Athens University of Economics and Business

10434 Athens, Greece