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SMERT: Energy-Efficient Design of a Multimedia Messaging System for Mobile Devices. Lin Zhong Rice University Bin Wei A&T Labs-Research Michael Sinclair Microsoft Research. Multimedia Messaging. 1. Compelling media sources. 1. 2. Relevant pieces constructed. 3.

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smert energy efficient design of a multimedia messaging system for mobile devices

SMERT: Energy-Efficient Design of a Multimedia Messaging System for Mobile Devices

Lin Zhong Rice University

Bin WeiA&T Labs-Research

Michael Sinclair Microsoft Research

multimedia messaging
Multimedia Messaging

1

Compelling media sources

1

2

Relevant pieces constructed

3

Rich content imposes more challenges on power usage

?

3

2

Tuesday, May 28, 2006 8:31PM

TeleComm(96 seconds)

In carefully worded statement, BellSouth, AT&T, and now Verizon have challenged a report that said the companies gave tens of millions of consumers' phone records to the National Security Agency as part of the war on terrorism after 9/11.

news program

text, images, audio, and video

energy cost
Device power profile

Communications

1600mW, GPRS

System

370mW, Busy

User interfaces

212mW, Display

Messaging service

Energy Cost

Message Text KFrames Video

Size 140 10K 696K

Auto Dnld (J) ~0.03 ~1.2 ~80

Manu Dnld (J) ~0.08 ~1.7 ~114

Consum. cost (J) ~5 ~10 ~48

Our Goal:

Optimizing multimedia messaging services,given the constraint of battery lifetime

our approach
Our Approach
  • Reconstruct message content
    • Different levels
    • Selective and incremental, instead of all-or-none
  • Utilize low-power user interface device
    • A wrist-worn low-power user interface device
    • Limited content with control interface
  • Reduce user interruptions
    • Battery-aware message fetching
    • Automatic downloading without energy consumption on display
smert a smart alert messaging system
MediaAlert messaging system

Watch

SMS

Notification

Fetching

Media-alerts of different qualities/formats

Web server

Mobile device

SMERT: A hierarchical multimedia messaging system for mobile users

SMERT: A SMart alERT Messaging System
smert sms vs mms sms
SMERT SMS vs. MMS/SMS
  • 140 Bytes
  • Short description of the message
  • URL to richer content
    • Different from conventional MMS/SMS
      • SMS: short message + control information
      • MMS: more detailed content
    • The device can choose when to download the content with which wireless interface
      • MMS is limited to the use of cellular networks
      • Our device can choose to use Wi-Fi, which can consume 10 times less energy than GPRS in data transfer if available
cache watch
Cache-Watch
  • Cache-Watch
    • Caches messages from phone
      • Data cache
    • Low-power secondary interface to phone
      • Interface cache
  • 100 X 132 Dot Matrix LCD
  • Three series of touch sensors
    • 1: mode switching
    • 2 and 3: displayed content manipulation
  • Browse/delete/confirm cached information
    • Synchronized with the phone periodically

Cache-watch 1.0

watch with invisible technology
Watch with Invisible Technology
  • Tech-heavy watches yet to prove wide social acceptance

Invisible text

Fossil Palm Watch

SPOT/MSN-Direct Fossil

  • A watch with usual appearance but one line of digital text display
    • Short text messages
    • Caller IDs
new development at rice
2x8 character low-power LCD

Debugging board

Both software and hardware will be OPEN-SOURCE!

New Development at Rice
energy efficiency benefit
3

Equivalent # of 20-second phone SMS access per hour

2.3

2

# of phone SMS accesses

1.4

1

0.7

0.6

0.5

0

0.5

1

3

5

10

Phone-CacheWatch synchronization interval (minute)

Energy Efficiency Benefit
  • Phone outsources simple-yet-frequent interactive tasks to Cache-Watch
    • Display usage reductionenergy reduction

One reduction in phone text message accesses per two hour will justify Bluetooth connection every 10 minutes

Benefit increases if lower power wireless personal-area technologies are used

smert fetching and notification
MediaAlert Messaging system

Watch

SMS

Notification

Fetching

Media-alerts of different qualities/formats

Web server

Mobile device

SMERT: Fetching and Notification
  • Fetching and Notification
    • Prioritize messages
    • Battery awareness (Evaluate battery)
  • Adaptive synchronization scheme
message prioritization
Message Prioritization
  • Priority is determined by match quality and quantity
    • Keywords are grouped in levels of different urgency
    • Matches are counted across groups; higher level dominates lower ones; more matches contribute more.
  • Delay-Tolerance Score (DTS)
  • Priority score is (1-DTS) which is between 1 (most urgent) and 0 (least urgent).

Informative (5-0)

Deferrable (10-0)

Critical (1-0)

l

m

n

∑ C + E * ∑ I + F * ∑ D

i

i

i

i = 1

i = 1

i = 1

DTS =

d *(l + m + n)

Critical: 1/10, 1/20, 1/30, 1/40, …

Informative: 5/10, 9/20, 12/30, 14/40,…

Deferrable: 10/10, 19/20, 27/30, 33/40…

battery evaluation
Battery Evaluation
  • Energy Optimism Score (EOS)
  • Battery-aware policies need information from both angles.
    • Priority score – the application perspective.
    • Energy optimism score – the device perspective.

RBC

EOS =

ECR * EWT

RBC: Remaining battery capacity

ECR: Energy consumption rate

EWT: Expected work time

battery aware policies
Battery-Aware Policies

Messages arrive as SMS

Phone-watch synchronization schedule

Notification policy

Through phone

Send to wrist

Fetching policy

Bluetooth

Decision sent back to phone

User decision

Fetch

Delete

CacheWatch

Default message notification

Message Gator on phone

battery aware fetching and notification
S

6

10

Battery-Aware Fetching and Notification
  • Notification policy depends on priority score and EOS.
    • Ignore low priority messages when EOS is low
    • Notify the user through the phone when priority is high
  • Automatic or user directed fetching
  • Tradeoffs among priority, EOS and message size, as

Y<0, P*EOS <= 0.5: immediate

P*EOS >0.5: k-frames

0

Y>1.5: clip

Fetching Factor (Y) = P * EOS -

P: priority score

EOS: energy-optimism score

S: the size of the smallest video format

communication need w r t message delay
Communication Need w.r.t. Message Delay

1000

900

800

Fixed interval

700

Adaptive-MAX=20, STEP=1

600

Adaptive-MAX=40, STEP=1

Total # of phone-watch communications

500

Adaptive-MAX=40, STEP=2

400

300

200

100

0

0

5

10

15

20

25

30

35

Average message delay (minutes)

design lessons
Design Lessons
  • Looking beyond the mobile device itself
  • Energy efficiency coupled with usability
  • Energy efficiency != less energy consumption
    • Maximize messaging services while achieving the targeted battery lifetime
conclusion and future work
Conclusion and future work
  • SMERT: an energy-efficient multimedia messaging system
  • Targets:
    • Reduce communication requirement
    • Minimize interruptions to the user
  • Methods:
    • Device hierarchy
    • Information richness versus battery usage
  • Future work
    • User studies
    • Multiple wireless networks for higher energy efficiency (supported by SMERT)
measuring power consumption
Measuring power consumption
  • Hardware
    • 0.1 ohm resistor in series inside battery
    • 1 KHz sampling rate
    • USB measurement device
thermal challenge
Thermal challenge

Every One Watt increases surface temperature by about 13 deg C

Simulation using FloTherm

Phone case temperature will be 40 deg C higher for a three-watt SMT5600.

Fuel cell batteries have <50% efficiency: one-watt heat for one-watt electricity

adaptive communication scheme
Adaptive Communication Scheme
  • Dynamically adjust phone-watch communication intervals
  • Traces
related work
Related Work
  • Internet alerts
    • Google alerts, Yahoo alerts, etc.
    • Most of them rely on email
  • Balancing application quality and energy conservation
    • Keeping track of power demand, supply, and usage history
    • Computation offloaded from mobile devices to wall-powered computers
  • Standard messaging framework
    • IMS
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