1. Enabling Opportunistic Resources Sharing on Mobile OS Benefits and Challenges S3 Workshop, Las Vegas, Nevada, September 2011 Narseo Vallina-Rodriguez, Christos Efstratiou, Jon Crowcroft University of Cambridge Geoffrey Xie Naval Postgraduate School

2. Motivation WiFi Bluetooth GSM/GPRS/3G Camera Accelerometer GPS CPU (Dual core) Storage (>4 GB) Context-aware apps Localised ads Online social nets … Augmented reality!

3. Energy limitations Energy-efficient hardware? Energy-aware software?

4. Poor UX

5. Resources availability and UX is context-dependent

6. Classic device-oriented resources management techniques Resource-specific optimisations Application-specific optimisations Adaptive resources management User-aware resources management Computation offloading to the cloud

7. Can we (in theory) do better?

8. “No-man is an island” John Donne

9. Enabling devices collaboration to save energy and improve UX

10. Las Ramblas, Barcelona. Any random day …

11. The Strip, Las Vegas Camden, London What if we are not in landmarks?

12. Resources diversity within a cluster of mobile users

13. Operator 1Operator 2 Signal Strength Cellular interfaces

14. GPS Accuracy, TTFF* and availability are context-dependent Urban canyon Canopy Indoors … A-GPS requires access to network! *TTFF, Time to first fix

15. Why at the OS-level? Transparent to applications More efficient (centralised) and secure

16. Does it make sense from an energy perspective?

17. Power consumption per hardware module OpenMoke Neo Freerunner BluetoothNear (30cm)36 mW Far (10m)44 mW WiFiIdle8 mW Full Capacity720 mW GSMIdle58 mW Full Capacity620 mW GPS143 mW Carrol & Heiser. “An analysis of power consumption in a smartphone”, USENIX anual tech. conference

18. Research challenges Appropriate wireless interface Bluetooth - slow discovery (10 s) :-( WiFi - high energy cost (similar to Cellular) :-( Resources advertisement Adaptive resources discovery/advertisement Cluster size depends on context

19. Research challenges User Mobility-related issues Dynamic clusters Bad for UX Can we predict the duration of the contacts?

20. Research challenges Collaboration and fairness Fair distributed energy cost among participating devices Are we selfish or altruistic? Incentive schemes adapted to users and context

21. Research challenges Selecting the right node Multiple factors can affect resources’ QoS Better understanding of HW

22. Related work Opportunistic networking Haggle project Enegy-aware Operating systems EcoSystem Quanto Odyssey Cinder ErdOS Project www.cl.cam.ac.uk/~nv240/erdos.html

23. Conclusions Opportunistic computing hasn’t been fully explored There are indications about the fact that opportunistic resources sharing can save energy and improve UX Still many challenges to be solved …

24. Questions? Thanks! Email: nv240@cam.ac.uk http://www.cl.cam.ac.uk/~nv240