Understanding Smartphone Traffic - DroidCon 2010

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Everyone enjoys the smartphone revolution - users, developers, network operators, device vendors and network equipment vendors such as Ericsson. However, there are challenges since the network systems have not been optimised for smartphones from start. Until recently, the key optimisation objectives for mobile broadband networks have been peakrate and throughput, which are still important properties. The advent of mass-usage of smartphones, and the related traffic, has shown that also other properties of the 3G radio and networks are important. In particular, the high frequency of data activities, sometimes with moderate volumes of data transferred, has lead to both a high battery drain, and increased the signaling load in the system, due to the transitions between the standardised states of the 3G radio.

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Understanding Smartphone Traffic - DroidCon 2010

  1. 1. understanding smartphone traffic impact on battery and networks Per willars, Ericsson
  2. 2. Public | © Ericsson AB 2010 | 2010-10-28 | Page 2 outline › Challenges with smartphone traffic › Understanding the 3G radio state machine › Shaping application traffic › Conclusion
  3. 3. Public | © Ericsson AB 2010 | 2010-10-28 | Page 3 outline › Challenges with smartphone traffic › Managing the radio connection › Shaping application traffic › Conclusion
  4. 4. Public | © Ericsson AB 2010 | 2010-10-28 | Page 4 battery Battery lifetime is a challenge with smartphones › Typically dominating: – display, when user is active – 3G radio modem, when inactive – (CPU) › Trend: – slow increase in battery capacity – faster increase in components peak power › Low duty cycle key for battery lifetime Example,Powertutorapp
  5. 5. Public | © Ericsson AB 2010 | 2010-10-28 | Page 5 3G Traffic load Comparison traffic per active device Data traffic Signalingtraffic Feature phones Smart Phones PCs Data: IP packets to/from apps, services, Internet Signaling: Mobile-specific messages for managing mobility and resources for the Data traffic Significant signaling x Many smartphones = Impact on some networks Signaling load increasingly important with smartphones
  6. 6. Public | © Ericsson AB 2010 | 2010-10-28 | Page 6 smartphone challenges overview Application server Internet Mobile Network Trade-off between: - Battery efficiency - Radio resources - Signaling & network resources - User experience (latencies) Device behavior New usage patterns Application behavior Network behavior Battery Radio resources Signaling & network resources User experience Chatty traffic Application behavior
  7. 7. Public | © Ericsson AB 2010 | 2010-10-28 | Page 7 smartphone challenges focus areas Application server Internet Mobile Network Trade-off between: - Battery efficiency - Radio resources - Signaling & network resources - User experience (latencies) Device behavior New usage patterns Application behavior Network behavior Battery Radio resources Signaling & network resources User experience Chatty traffic Application behavior Shaping application traffic Managing the radio connection
  8. 8. Public | © Ericsson AB 2010 | 2010-10-28 | Page 8 outline › Challenges with smartphone traffic › Managing the radio connection › Shaping application traffic › Conclusion
  9. 9. Public | © Ericsson AB 2010 | 2010-10-28 | Page 9 Data rate / lower latency / resources Powerconsumption(relative) 1 0.5 0.01- 0.02 HSPA FACH “Standby”Idle 3G Radio states balancing data transfer, battery and resources ~ 2s inactivity ~ 10-30 s inactivity ~ 10-30 min inactivity Activity Activity ~ 256 byte UL ~ 512 byte DL with IP headers Activity “High” “Low” URAIdle IDLE CONNECTED › Signaling needed for state transitions, esp. to/from Idle › ”Standby” state (URA) deployed in more and more networks Typical trigger thresholds
  10. 10. Public | © Ericsson AB 2010 | 2010-10-28 | Page 10 Power HSPA FACH “Standby”Idle device-triggered fast dormancy Today - aggressive disconnect to save battery “High” “Low” URAIdle IDLE CONNECTED › Device trigger: data + display inactivity › Problems: latency, signaling, shortcuts “Standby” state ~ 3s inactivity Data rate
  11. 11. Public | © Ericsson AB 2010 | 2010-10-28 | Page 11 HSPA FACH “Standby”Idle device-triggered fast dormancy future solution – standardized behaviour “High” “Low” URAIdle IDLE CONNECTED › Device-triggered battery efficiency in ”Standby” state › Short-term recommendation: – shorter timers in networks, selective Fast Dormancy in device Power Data rate
  12. 12. Public | © Ericsson AB 2010 | 2010-10-28 | Page 12 outline › Challenges with smartphone traffic › Managing the radio connection › Shaping application traffic › Conclusion
  13. 13. Public | © Ericsson AB 2010 | 2010-10-28 | Page 13 shaping application traffic › Guiding principles – Stay in battery-efficient states – Minimize state transitions – Minimize intermittent small transactions – When transmitting – transmit it all – Small keepalive messages Reduces battery consumption and network signaling HSPA FACH “Standby”Idle “High” “Low” URA IDLE CONNECTED Power Data rate
  14. 14. Public | © Ericsson AB 2010 | 2010-10-28 | Page 14 shaping application traffic bad application example Device Network 3s 5s 50s 3s 5s3s 5s 50s 3s 5s › Chatty IM application example – 2% of traffic generated 10% of signalling load – Lots of signaling due to frequent polling › Possible improvements: – Clean close of TCP (avoid TCP RST) – Keeping TCP connection (to own server) – Push on one persistent TCP connection “High” “Low” Idle
  15. 15. Public | © Ericsson AB 2010 | 2010-10-28 | Page 15 background polling applications › Multi-tasking: freedom with responsibility – higher risks screwing up! › Developer tutorial from Sony Ericsson blog: – Synchronize polls with other apps › using alarmManager: setInexactRepeating and/or use RTC rather than RTC_WAKEUP – Execute polls as short as possible › single requests, short server responses, multi-queries, gzip – Manage HTTP connections › use of Apache httpclient and explicitly shut down the connection when poll is done – Stop services › wake up with intents (e.g. alarmManager) when needed http://blogs.sonyericsson.com/developerworld/2010/08/23/android-tutorial-reducing-power-consumption-of-connected-apps/
  16. 16. Public | © Ericsson AB 2010 | 2010-10-28 | Page 16 synchronize background polling example on synching android apps HTC Hero, Android 1.5. Trace on WLAN. Showing all TCP activities. FB app Contacts FB POP3 mail Twitter Google port 5228 Google/loc/m/api Daytime Snowstorm weather Newsrob RSS google reader AGPS Poweron Manual refreshes Charging Wake display
  17. 17. Public | © Ericsson AB 2010 | 2010-10-28 | Page 17 push instead of polling Android 2.2 Cloud-to-device messaging (C2DM) API CP/SP CP/SP Android App App API Google Internet 1. New event / data 2. Message to ”ID” Data up to 1 kB 3. Message to ”ID” 4. Message to app. Download more data and/or notify user. long-lived TLS/TCP (port 5228) also used for GTalk, Gmail,... › Push more efficient if: – high immediacy is required – frequency of data is not too high › Further optimizations: – multiple apps share single connection (c2dm) => reduced keepalives – transmit only delta => no need for additional polls FW/NAT c2dm Server
  18. 18. Public | © Ericsson AB 2010 | 2010-10-28 | Page 18 small keepalive signaling › Minimize size of keepalive messages – Allows switch from ”Standby” (URA) to stay in ”Low” (FACH) state – Avoid upswitch by limiting data Typical settings in todays networks: Uplink < 250B, Downlink < 500B, incl IP headers Establishment Infotransfer Inactivity “High” “Low” “Standby” “Low” “Standby” PowerPower Save battery, use small keepalive messages 6 messages over radio 3 messages over radio FACH URA HSPA FACH URA
  19. 19. Public | © Ericsson AB 2010 | 2010-10-28 | Page 19 optimizing video streaming 1. Download start at peak rate 2. Server throttling 3. Client throttling › Staying long in ”High” (HSPA) state drains battery › More efficient: transmit with peak rate, then sleep the radio – Intervals long enough to use power-saving state, but not too long since many videos not viewed fully – Consider adaptive HTTP streaming (upcoming – not yet in Android) Long Youtube video on Android Time [s] Throughput[Mbps]
  20. 20. Public | © Ericsson AB 2010 | 2010-10-28 | Page 20 conclusions › Smartphones a success for all involved › Chatty smartphone traffic – Impacting battery and network signaling › Measures to manage smartphone traffic – Network dimensioning, tuning and features – Device behaviour - fast dormancy – Impact application traffic to be battery- and radio-efficient › minimize chattiness of traffic › optimize background traffic › small & infrequent keepalives › when transmitting – transmit it all NW operators/vendors Terminal vendors App developers
  21. 21. Public | © Ericsson AB 2010 | 2010-10-28 | Page 21 developer guidelines, some references › Our blog post on this topic: – https://labs.ericsson.com/developer-community/blog/smartphone- traffic-impact-battery-and-networks › Android Application Coding Guidelines, Power Save: – http://developer.sonyericsson.com/cws/download/1/788/263/127192 0135/dw-300012-Android_Power_Save.pdf › Android tutorial, Reducing power consumption of connected apps: – http://blogs.sonyericsson.com/developerworld/2010/08/23/android- tutorial-reducing-power-consumption-of-connected-apps/ › Coding for Battery life, Google IO 2009: – http://www.youtube.com/watch?v=OUemfrKe65c
  22. 22. Q & A
  23. 23. Public | © Ericsson AB 2010 | 2010-10-28 | Page 23

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