Distribute what you can, centralize what you must
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Transcript Distribute what you can, centralize what you must
Distribute what you can,
centralize what you must!
Narseo Vallina-Rodriguez
Supervisor: Jon Crowcroft
Qualcomm – Cambridge
22nd May 2013
Motivation
The web is becoming mobile
Apps rely on multiple online/cloud services (mobile
mashup):
CDNs (Akamai)
Cloud services (Amazon WS)
Authentication APIs (Oauth)
Assisting sensors (A-GPS)
Advertisement (AdMob, Burstly, Millennial Media, …)
Push notifications (Google’s GCM)
NAT punching for P2P (Skype)
Research question
How do mobile apps’ cloud dependency
impact on cellular network and
battery life of mobile handsets?
2012-2013 outcome
When Assistance becomes Dependence: characterizing the costs
and inefficiencies of A-GPS. Vallina-Rodriguez, Finamore,
Grunenberger, Papagiannaki and Crowcroft. ACM SIGMOBILE
MC2R (under review)
Breaking for Commercials: Characterizing Mobile Advertising.
Vallina-Rodriguez, Finamore, Shah, Grunenberger, Haddadi,
Papagiannaki and Crowcroft. In ACM Internet Measurement
Conference 2012(IMC'12)
Energy Management Techniques in Modern Mobile Devices.
Vallina-Rodriguez and Crowcroft. In IEEE Communications Tutorials
and Surveys, 2012.
When David can help Goliath: the case for cellular augmentation
of wired networks. Vallina-Rodriguez, Erramilli, Grunenberger,
Gyarmati, Laoutaris, Stanojevic, Papagiannaki, In ACM HotNets'12
Signposts: End-to-End Networking in a World of Middleboxes.
Aucinas, Chaudhry, Crowcroft, Probst Eide, Hand,
Madhavapeddy, Moore, Mortier, Rotsos and Vallina-Rodriguez. In
ACM SIGCOMM 2012. DEMO
Take away: moving to the edge!
1. Mobile applications may abuse cellular networks: they cause
network (signaling/channels/operational) and energy costs!
2. Fetching content in a centralized fashion is not the only way
Distribute as much as
you can!
Flashlinq/LTE-direct
P2P wireless technology
Perfect candidate for transparent communication in the edge!
Peer discovery (energy efficient)
Expression-based discovery (service)
Always-on background service with low duty-cycle
Similar to powering up a paging channel every X seconds
Current prototype performance:
Low-latency (<10 ms)
Good throughput (~ 20 Mbps)
Discovery (1~2 seconds)
… but what can be
distributed?
1. Localized data
Use case 1: Localized data
A large fraction of mobile data is local
Weather
Notifications
Ads
[Cellular data network infrastructure
characterization and implication on
mobile content placement, Xu et al.
SIGMETRICS’2011]
Apps use cellular networks and push notifications to fetch
this content
High latency
No delivery guarantees
Use case 1: Airport notifications
Use case 1: Airport notifications
Traffic Pattern Heathrow App For Android (Flight Update)
Energy
Signaling
Spectrum (HSPA)
TCP/IP Push notification model is broken for local data:
Frequent RNC promotions (some caused by TCP Heartbeats)
Waste of energy, middleboxes/proxies memory and radio
channels (+200K users/day, a lot of signaling traffic!)
Use case 1: Airport notifications
2. Collaborative sensing
Use case 2: Collaborative A-GPS
Assisting data (time, ephemeris, almanac, coarse
location) downloaded from network:
Reduces TTFF (usability)
Temporal validity up to 2 weeks for ephemeris
Problem: use of cellular network may impair performance
and increase energy costs!
Use case 2: Collaborative A-GPS
2x current!
Control-plane
latency
Use case 2: Collaborative A-GPS
Collaboration between devices in a P2P fashion:
Context-awareness (sense environment so do not turn on
AGPS indoors!)
Share/pre-fetch assisting data (reduces latency to fetch
data)
Prototype for Nexus One:
Pre-fetch and cache of assisting data
Devices can detect if they’re indoors in less than 10 seconds
Blackbox. Hard to inject assisting data on chipsets (A-GPS is
controlled by binary/proprietary files/drivers )
3. Wired-wireless
integration
Use case 3: Wired-wireless integration
3G offloading to WiFi and femtocells:
Reduce network traffic
No real benefit for users (unless volume cap in data-plan)
Wired network can be constrained!
Can cellular networks augment wired networks?
Wired nets deployment is $$$
Cellular nets have good coverage
Use case 3: Wired-wireless integration
Cellular network can
provide more capacity
than wired ones (DSL)
4.7 Mbps
Spare capacity on cellular
network
Powerboost for videostreaming apps
2 Km
2.8 Mbps
Use-and-release
Does NOT work
everywhere anytime!
20
Use case 3: Wired-wireless integration
2x downlink/5x uplink
for most locations with 1
mobile device
Simulation: 50% of the
videos have a speed
up factor of 10x
Conclusions
Current cloud-mobile model is not efficient
Hyper-centralized: push notifications
Lack of connectivity between handsets: missing
opportunities
Cellular and wired networks are fully decoupled
Flashlinq/LTE-direct can bring a new mobile paradigm!
Energy and network efficient
Distributed
Flexible
Flashlinq limitations and extensions
Transparent security/authentication mechanisms
Lessons to be learnt from the past: Bluetooth and WiFi-direct
failed!
Source of DoS/Privacy/Energy attacks
Global Signpost-ish naming (OpenSource, DNSSEC based)
Low-level radio details must be exposed to OS!
Too much layering hides inefficiencies: e.g. A-GPS and 3G
Cross-layer optimizations are key (e.g. iPhone vs. Android)
Incentives for operators?
Reduce operational costs: better use of limited capacity
Licensed frequency
Thank you for your attention!
http://www.cl.cam.ac.uk/~nv240
[email protected]