Stephan Goebbels, ComNets, RWTH Aachen University

Smart Caching in Mobile IP enabled Networks

Stephan Göbbels

Chair of Communication Networks RWTH Aachen University, Germany

13. ComNets-Workshop, Mobil- und TelekommunikationMarch 31st, 2006, Aachen, Germany

13. ComNets-Workshop 200613. ComNets-Workshop 2006

2Stephan Goebbels, ComNets, RWTH Aachen University

• Motivation and Introduction• The Smart Caching Approach• System Concept• Simulation

– Scenario– Results

• Conclusion and Outlook

OverviewOverviewOverview – Introduction – Smart Caching – Simulation - Outlook

3Stephan Goebbels, ComNets, RWTH Aachen University

• Strong development towards All-IP networks– Heterogeneous network structure– Combination of wired and wireless networks – Ambient Networks

• Integration of various wireless networks – Always Best Connected– Intersystem handovers

• Different performance characteristics of involved communication technologies– Maximum and average throughput – Packet delay and latency– QoS – …

• Goal: Improve user satisfaction and network performance

• New upcoming services– Video on Demand– Online VCR– IPTV

MotivationMotivationOverview – Introduction – Smart Caching – Simulation - Outlook

4Stephan Goebbels, ComNets, RWTH Aachen University

• Aggregation of mobile communication networks– Integration of buffer on aggregation

level– Closest point between IP gateways

(SGSN, gateway router, …)

• Smart Caching:– Caching Media Port (CMP)– Decoupling of backbone and radio

subsection of the end-to-end connection

– Optimal utilization of available wireless bandwidth

– Virtually continuous broadband connection (for non real-time services)

• Hierarchical Mobile IP shows similar structure to Smart Caching– Integration of Mobility Anchor Point

(MAP) and CMP

IP world

GPRS

CMP MAP

Server

Backbone

AggregationLevel

AggregationRouter

RadioLevelWLAN

IntroductionIntroductionOverview – Introduction – Smart Caching – Simulation - Outlook

5Stephan Goebbels, ComNets, RWTH Aachen University

• Aggregation of discontinuous high bandwidth wireless links (WiFi) and continuous basic coverage (Cellular networks – GPRS/UMTS)

• Idea:– Buffer data if wireless link is overloaded– Forward data if radio bandwidth is available on top of current traffic Full utilization of wireless link – maximum throughput

• Store enough data at the end device in order to bridge idle gaps and pretend a continuous service– Buffered video data– Cached WWW sites– …

• CMP between SGSN and WLAN Gateway router

• Integration with Mobile IP– Micro mobility by MAP and Macro mobility by Home Agent– MAP can trigger data delivery of CMP – MAP switched => new CMP

The Smart Caching ApproachThe Smart Caching ApproachOverview – Introduction – Smart Caching – Simulation - Outlook

6Stephan Goebbels, ComNets, RWTH Aachen University

• Caching node (CMP):– Client entity to communicate

with service provider– Server entity to forward

traffic to end device

• Continuous traffic on first hop

• Major part of control traffic only on second hop

• Better performance of communication (TCP, ARQ,…) and session management protocols

• Location update triggers data delivery

System ConceptSystem ConceptOverview – Introduction – Smart Caching – Simulation - Outlook

Server Caching Client Caching Server Client

Data request

Sending data

… Caching…Data forward

Packet request

Ack

Packet request

…

No ack

Stop

deliveryLocation update

Packet request

…

Data forward

7Stephan Goebbels, ComNets, RWTH Aachen University

...160m0m 1440m

AP1 AP2 AP10

d

IP world

CMP / MAP

Simulation ScenarioSimulation ScenarioOverview – Introduction – Smart Caching – Simulation - Outlook

• Applied service: Video streaming (400 kbit/s)• CMP and MAP are collocated in one gateway node• Heterogeneous

network structure by only partial coverage of 10 WLAN Access Points (802.11b – 11 Mbit/s)

• Varying coverage ratio (10 – 75%)

• Consummation rate 300 kbit/s

• Legacy network technology for reference reasons

8Stephan Goebbels, ComNets, RWTH Aachen University

0 50 100 150 200 250 300 350 400 450 5000

500

1000

1500

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2500

Location [m]

Cu

rre

nt T

hro

ug

hp

ut [

kbit/

s]

Throughput

Coverage

Simulation ResultsSimulation ResultsOverview – Introduction – Smart Caching – Simulation - Outlook

• Currently perceived user throughput

• Optimization of wireless link utilization

• Increased throughput after first coverage gap

• Note: – Session recovery

delay– Full utilization of

wireless link

9Stephan Goebbels, ComNets, RWTH Aachen University

Simulation ResultsSimulation ResultsOverview – Introduction – Smart Caching – Simulation - Outlook

• Average throughput for long-term session• Increase of average throughput• Comes close to the maximum reachable

throughput • Doubles Throughput

in 50% coverage scenario

• Effect is amplified if coverage ratio decreases (as long as coverage zones are not fully utilized)

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Caching-enabled

Reference

maximum Throughput

average Throughput

10Stephan Goebbels, ComNets, RWTH Aachen University

0 500 1000 15000

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75%

50%

25%10%

Reference

Simulation ResultsSimulation ResultsOverview – Introduction – Smart Caching – Simulation - Outlook

• Decreasingperformance with sinking coverage ratio

• But: Improvement ifcompared to reference level

• Difference between full utilization and partial utilization (25% coverage is lower limit)

• Below 25% only partial improvement (buffer overflow)

11Stephan Goebbels, ComNets, RWTH Aachen University

Simulation ResultsSimulation ResultsOverview – Introduction – Smart Caching – Simulation - Outlook

• Fill level of user equipment buffer• Decides whether an virtual continuous service can

be provided.• In reference scenario usually not possible• Even 30% network

coverage is almost enough

• In 50% case an overspending of resources

0 100 200 300 400 500 600 700 8000

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ffere

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ata

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yte

]

Caching 50%

Reference 50%

Caching 30%

Reference 30%

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Conclusion and OutlookConclusion and OutlookOverview – Introduction – Smart Caching – Simulation - Outlook

• Integration towards ALL-IP networks will cause several problems for service provisioning

• Smart Caching is suitable protocol to enhance network performance in new heterogeneous network structures– Support of mostly unidirectional services– Allows prefetching of user data

• Benefits from integration of Hierarchical Mobile IP and Smart Caching

• Virtual continuous broadband connection in patchy coverage areas (suitable for video services like IPTV)

• Future improvements:– Stronger integration of Mobile IP and Smart Caching protocol– Combined GPRS – WLAN scenario– Switching of MAP/CMP

13Stephan Goebbels, ComNets, RWTH Aachen University

Thank you for your attention !

Stephan Göbbelssgs@comnets.rwth-aachen.de

Any questions?