1. Characterizing Smartwatch Usage In The Wild
Xing Liu, Tianyu Chen, Feng Qian, Zhixiu Guo, Felix Xiaozhu Lin, Xiaofeng Wang,and Kai Chen

3. Towards Understanding the Smartwatch Ecosystem
How users interact with smartwatch?
How energy efficient is smartwatch?
Can we optimize the battery usage?
What is the network behavior?

4. Outline The user study infrastructure Usage patterns
Energy consumption
Network traffic

5. The Smartwatch User Trial
Crowd-sourced measurement study involving 27 users
Limited experiences using smartwatch

6. The Data Collection Data collector 106-day dataset, 37 GB of data
Automated – transparent to user
Reliable – negligible down time
Lightweight – CPU overhead < 3%
Energy efficient – energy overhead < 3%
106-day dataset, 37 GB of data

7. Outline The user study infrastructure Usage patterns
Energy consumption
Network traffic

8. Android Wear State Machine

9. Duration Spent across the States

10. Push Notifications 200+ phone apps push notifications to watch
An average user receives 40 notifications per day

11. Push Notifications How predictable are push notifications?
Difficult in the long term
Strong bursty pattern in the short term
The median inter-arrival time is only 49 seconds
Problematic push logic

12. Smartwatch App Usage Smartwatch run 3rd-party apps
Avetage # apps installed on a watch: 18
Activity vs. Service
Activity: a visible user interface
Service: runs in the background without UI
Service execution duration = 56x activity duration
70% of service execution < 1s

13. Outline The user study infrastructure Usage patterns
Energy consumption
Derive fine-grained power model
Apply the power model to our dataset
Study methods for improving energy efficiency
Network traffic

14. Energy Consumption in the Wild
Power
Model
Post
Processing
User
Study
Trace
Energy
Utilization
Stats.

15. Energy Consumption in the Wild
Network incurs little E consumption
CPU accounts 29.3%, Display contributes to 30.2% despite the small screen
Dozing consume more than half of overall E.
Awake state consume 26.6% of overall E
A fully charged watch can last for about 41.7 hours

16. Improve Smartwatch Energy Efficiency
4 methods for improving the smartwatch energy efficiency
Tuning the state machine timers
Optimize OLED display
Bundling delay-tolerant push notification
Building workload aware CPU configuration

17. Outline The user study infrastructure Usage patterns
Energy consumption
Network traffic

18. Smartwatch Networking
Our LG Urbane watch has both WiFi and Bluetooth.
For most of the time(80%), the watch and phone are paired.
Most traffic(91%) is delivered over BT.
Most BT traffic(89%) is downlink (phone → watch).

19. Characteristics of BT Traffic Flows
Compared to smartphone traffic, smartwatch traffic flows are…
Small: 77% of flows are smaller than 10KB
Short: 53% of flows are shorter than 1sec
Low rate, Average UL rate:~ 6kbps; Average DL flow rate: ~15kbps
Highly bursty
WiFi/BT handover is poorly supported

20. Limitation Lacks device diversity Participants have limited diversity
Android Wear 2.0 is up

21. Summary
A first comprehensive measurement study of smartwatch usage “in the wild”
Focus on three aspects:
User Usage patterns
Energy consumption
Network traffic
Smartwatch usage is highly different from smartphone!
Provide key knowledge and hints for future system design