Outline - MICREL

Transcript

Outline - MICREL

Energy Efficient System Design
for Pervasive Computing and
Ambient Intelligence
Elisabetta Farella
Davide Brunelli
Andrea Acquaviva
efarella|dbrunelli|[email protected]
DEIS – University of Bologna
19 Marzo 2004
Corso di Metodologie di
Programmazione HardwareSoftware
Outline
• Ambient Intelligence (AmI) in general
• Building blocks: Enabling technologies
– Many different data: audio, video, motion…
– Key
- point: energy efficiency
Applications:
¾ Interaction with (Wireless) Personal
Devices
¾ Natural Interfaces
¾ Context-Aware Computing
19 Marzo 2004
1
Outline: Applications
• Interaction through (Wireless) Personal
Devices
– PDA & VR
– mobile systems & 3D graphics
• Natural Interfaces
– MOCA
• Intuitive Interfaces – Context Aware
Computing
– Localization (IEEE 802.11b, RF modules,
Bluetooth)
19 Marzo 2004
Intelligent media environment
electronic environments
that are sensitive and
responsive to the
presence of people
AmI = Ubiquitous
computing + intelligent
social user interfaces
AmI at Philips, a video:
http://www.date-conference.com/conference/2003/keynotes/
19 Marzo 2004
Ambient intelligence envisions a
world where people are
surrounded by intelligent and
intuitive interfaces embedded in
the everyday objects around
them. These interfaces recognize
and respond to the presence and
behavior of an individual in a
personalized and relevant way.
2
Technology is
- Invisible
– Use/functions are immediately apparent
- Ubiquitous:
– Available anywhere, integrated in physical
environment & object around us
- Intelligent:
- Relevant to user & context- a
ware
- Unobtrusive
- Providing meaning (knowledge vs information)
19 Marzo 2004
Challenges (1)
- Augmenting objects/environments with sensing,
computing & networking capability
- Sense & model the user’s behavior AND Infer the
user’s current interests/intentions
- Design (proactive) interfaces that offer value
without being obnoxious, while being highly
relevant
- Integrate these interfaces in user’s physical
environment in seamless, natural way:
- On the body: cell phones, wearables
- In the ennvironment: architecture, ether, objects
19 Marzo 2004
3
Challenges (2)
• Multi-user support
• Multimedia data support
• Platform independence and
management of hardware resources
heterogeneity
• Hybrid (wireless) communication
interfaces
19 Marzo 2004
Our approach
• Leverage state of the art technology
– Limited development of new hardware
– COTS-centric approach
• …but manage it effectively
– Manage parsimoniously available
resources (Power management)
– Focus on software optimization
– Build a reusable software infrastructure
19 Marzo 2004
4
Building blocks: Enabling
technologies
Energy efficient system
design
19 Marzo 2004
General picture
SNAFI
MOCA
LP-LINUX
VR&
GAMES
VIDEO
STREAMING
APPLICATION
MIDDLEWARE
OS
HAL
HARDWARE
19 Marzo 2004
5
Energy efficient system design
• Operating system layer
• Network layer
•…
• Cross-layer:
– Server driven approach
– Video streaming optimization techniques
19 Marzo 2004
The Middleware infrastructure:
LP-Linux
operating system
resource needs
Power Manager
Applications
Kernel
workload
Device driver
CLK speed, power states
Hardware
19 Marzo 2004
6
LP-Linux: effectiveness
Energy(J)
3
2,5
No Policy
2
DPM
1,5
DPM+DCS@191MHz
1
0,5
0
Comparison between policies for
MPEGIII and Speech Recognizer
• DCS = Dynamic Processor Clock Setting
• DPM = Dynamic Power Management of
Processor and Devices
30% power reduction for MP3 & ASR
running together on HP’s SmartBadgeIV
19 Marzo 2004
Energy-efficient MM
streaming
• Key issue: wireless communication is
power-hungry (e.g., 1.5W for 802.11b)
• Reduce power with controlled QoS
degradation
– Transport layer power optimization
• Application independent
– Server-
driven power optimization
• Application dependent
19 Marzo 2004
7
Communication channel idleness
Shut-down NIC in idle period at the transport layer
active mode
Energy
300 ms for
a Cisco Aironet Card
sleep mode
Time
z Large overhead due to the network reassociation time
z TCP idle periods are in the order of the RTT
z We need coarser-granularity idle periods
Monitoring TCP buffer occupancy
19 Marzo 2004
Buffer Level
TCP Buffer Occupancy
Time
¾
¾
¾
¾
Application consuming rate is slow wrt network bandwidth
Very high average buffer occupancy
The network interface is always on
“Zero window” mechanism prevents receive buffer overflow
19 Marzo 2004
8
TCP Buffer full policy
server
ACK
client
ACK, Stop sending
ACK, Keep sending
¾ Keep sending command
against threshold
crossing:
“SWS avoidance”
¾ Buffer size and threshold
are parameterizable
¾ The activity profile of the
NIC is modified so to be
energy-aware
Buffer Level
Card
in sleep
mode
packet
Time
19 Marzo 2004
Energy Savings
¾ We run low-power TCP combined with MAC layer power
management techniques, in-built in the NIC
¾ The same scaling properties are observed
¾ Our transport protocol optimization adds significant savings
¾ Performance penalty is minimal
19 Marzo 2004
9
Server-Driven Approach
• The server decides the power
management policy of WNIC
– Enable/disable 802.11PM
– Adjust 802.11PM parameters
– Perform traffic reshaping and switch off
WNIC during coarse idle periods
• Advantages
– Exploit server knowledge of workload
– Discard useless broadcast traffic
• Efficient trasmission scheduling in
multiple client environments
19 Marzo 2004
Client-server architecture
SERVER
PM
PM INFO
CLIENT
PM
SERVER
TCP/IP
HP’s SMARTBADGE4
POWER MANAGER
SERVER
APP
DATA
CLIENT
APP
APPLICATION
• The power manager can be split in PM
Server & PM Client
19 Marzo 2004
10
PM Policy
BURSTS
BROAD
CAST
SHUT-OFF
BROAD
CAST
CARD
WAKE-UP
DELAY
SHUT-OFF
DELAY
WAKE-UP
WAKE-UP
• The server performs traffic reshaping to create
coarser idle intervals of the WNIC
– Shut-off WNIC
– Large intervals compensate for wake-up delay
• No energy spent to listen for broadcast traffic
discarded during off times
19 Marzo 2004
Results
WLAN Avg Power (mW)
1200
• 1st benchmark
No PM
802.11b PM
Server PM
1000
– 30 frame/sec
– Highly variable
decoding complexity
– 40% of power
reduction
800
600
400
200
0
size = 80
size = 70
WLAN Avg Power (mW)
No PM
802.11b PM
Server PM
1200
• 2st benchmark
1000
– 15 frame/sec
– Low variable decoding
complexity
– 65% of power
reduction
19 Marzo 2004
size= 50
BURST SIZE
800
600
400
200
0
size = 80
size = 70
size= 50
size=20
BURST SIZE
11
Video Capture
A cross-layer research project
19 Marzo 2004
Video Acquisition & Transmission
Microprocessor-based
General-purpose
Wearable System
+
USB Video Camera
Wireless NIC
General-purpose OS
Device Drivers
Application Software
9 Low-cost
9 Commercial off-theshelf
9 No dedicated HW
¾ High Performance?
¾ Low-Power?
19 Marzo 2004
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Hardware Platform
19 Marzo 2004
Software Optimizations
Driver/OS level
¾ LOCAL OPTIMIZATION
Float-fixed point conversion (for
architecture with no HW FPU)
¾ EFFICIENT TASK DISTRIBUTION
move YUV/RGB conversion from
wearable video acquisition server to
remote video client
Application level
¾ EFFICIENT TASK SYNCHRONIZATION
exploit buffering to decouple
dependent task and maximize
processor utilization
19 Marzo 2004
13
Software Versions
Release 1:
9 flot – fixed point conversion
9 1.5 fps hi-res, 5.5 fps lo-res
Release 2:
9 Remote YUV-RGB conversion
9 4 fps hi-res, 16 fps lo-res
Release 3:
9 Efficient buffering & task
sinchronization
9 8.5 fps hi-res, 31.5 fps lo-res
19 Marzo 2004
Results
We get a frame rate of 31
frame/sec in Low-Res and of 8.5 in
High-Res
We obtain a performance speedup of a factor of 5 with a negligible
increase of power consumption
f
r
a
m
e
r
a
t
e
(
f
p
s
)
35
30
25
20
Rels. 1
Rels. 2
Rels. 3
15
10
5
0
352*288
176*144
P
o
w
e
r
(
W
)
3,5
3
2,5
Rels. 1
Rels. 2
Rels. 3
2
1,5
1
We improve the energy efficiency
of the system of about 80%
0,5
F
r
a
m
e
P
o
w
e
r
(
W
)
0
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
19 Marzo 2004
352*288
176*144
We obtain performance/power by
optimizing the system software at
Rels. 1
Rels. 2
Rels. 3
352*288
176*144
driver and application level
14
Outline: Applications
• Interaction through (Wireless) Personal
Devices
– PDA & VR
– mobile systems & 3D graphics
• Natural Interfaces
– MOCA
• Intuitive Interfaces – Context Aware
Computing
– Localization (IEEE 802.11b, RF modules,
Bluetooth)
19 Marzo 2004
Interaction with (Wireless)
Personal Devices
PDA & VR
Mobile systems+3D graphics
Collaborative systems
19 Marzo 2004
15
Enabling technologies:
Hardware Components
GPRS, Bluetooth,
IEEE 802.11b
Immersive technologies,
Projection screen, CAVE
Mobile low-power
terminals
19 Marzo 2004
HW for 3D models
+ real-time rendering
middleware
Java Server Application
Java Application
Java Native Interface - JNI
RMI + JNI
Java Virtual Machine
Multi – client
WINDOWS CE
Object selection
manipulation
POCKET PC
Client
19 Marzo 2004
Syncronization
images and text
P2P
communication
C Layer
Vega
Performer
OpenGL
IRIX
Hardware
Server
16
middleware
Actor- based Architecture
• Implementation of a communication layer
supporting a flexible and performant
interaction for heterogeneous (and mobile)
systems
Simple Network Architecture for Fast
Interaction (SNAFI)
Sender
Receiver
Actor
Actor
TCP / UDP
Actor
Actor
Receiver
Sender
Actor
19 Marzo 2004
Performance Comparison
120
32768
100
Lag (msec)
80
SNART
SNAFI
60
RMI
16384
40
8192
20
4096
2048
2
0
1
4
8
16
10
32
64
128
256
512
100
1024
1000
10000
100000
Size (byte)
19 Marzo 2004
17
Test-beds
a. Interaction with
Immersive Virtual
Environment
through PDAs
b. Remotization of
game interfaces
19 Marzo 2004
Virtual Reality
• VR effectiveness:
– Immersive experience
– Sense of Presence
– Real-time Interaction
19 Marzo 2004
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Interaction in IVR
• User
interaction
in
IVR
and
environments
traditionally
based
specialized devices
AR
on
– Small
niche
market
(consequences
on
costs,
optimisation)
optimisation)
– Avarage user (especially in CH) not familiar with VR
interfacing devices (learning time)
– Tethered – limited freedom of movement
• invasive GUI
– 2D in 3D world (sense of presence and immersion)
– 3D widgets or virtual interaction devices
19 Marzo 2004
… introducing mobile devices:
PDA, cell phones….
• Familiar interfaces for a large user basis
• Price decreasing while quality, reliability
and usability improving (consumer market
pros)
• Personal and wearable, increasing Hw/Sw
resources
• Easy interaction with large amount of data
and alphanumeric information
• Wireless networking (IEEE 802.11b, GPRS,
Bluetooth).
19 Marzo 2004
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…improving interaction
• Enabling peer-to-peer, many to
many communication of multiple
users sharing the same environment:
collaborative fruition of VH content
• Applications:
– Virtual Archaeology – Virtual Museums
– Edutainment
– Entertainment
19 Marzo 2004
…challenges
• Use of ubiquitous and wireless
technologies =
– Limited software/hardware resources of
mobile devices
– Heterogeneity
– Real-time performance to guarantee on
wireless networks
19 Marzo 2004
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Case study
• Wireless
Interaction
Platform (for
navigation and IVE
control)
• Multimedia support
(e.g. 3D model validation
through video, images, text
collected during excavation)
• Cooperation (multiclient features)
19 Marzo 2004
Case study
• Wireless Interaction Platform
• Multimedia support
• Cooperation (multiclient
features)
See video demonstration at
http://wwwmicrel.deis.unibo.it/~farella/research.html
19 Marzo 2004
21
Remotization of game
interfaces
• VR&PDA : enabling interaction with
high-end graphics hw-sw (Virtual
Theater & co) with low-end
interaction device (PDA)
• A step forward: consumer platform
for 3D graphics
19 Marzo 2004
Current wk: Remotization of
game interfaces
¾ Low/Medium end visualization hardware
¾ Exploit low-cost high-performance graphics
cards
¾ Exploit software infrastructure of game engines
¾ 3D Game Studio
¾ Quake
¾ Advanced Game Studio (2D)
19 Marzo 2004
22
SW Architecture
Scene Rendering
Game Engine
DLL plugin
Network
Framework
Multimodal
Interaction
Mobile and
Wearable
Devices
19 Marzo 2004
Interface &
Feedback Manager
Example
video
Multiplayer interaction
Sharing the Scene
19 Marzo 2004
The interaction GUI
is on the mobile terminal
(+ sense of presence
and
immersivity)
23
Enhancing interaction
through natural interfaces
Gesture, voice, gaze…
MOCA
19 Marzo 2004
Motivation
• Desktop PC traditional interfaces
(mouse, keyboard) are not targeted
for interaction with mobile and
wearable devices
• Research solution: Natural interfaces
– Speech
– Gaze, Facial Expression
– Gestures/Motion tracking (app. VR,
Gaming, Security)
19 Marzo 2004
24
Requirements
• Available Motion Tracking technologies target
animation of synthetic characters
– High-accuracy (<cm) but complex calibration processes
– High-costs (>50K$)
– Requires infrastructure and Limited operating range
• Enabling gesture interfaces for mobile devices- >
tracing moving body parts in real- time with
–
–
–
–
–
Reduced Accuracy
Low-power consumption
Limited processing capabilities
Unconstrained mobility
Low-cost (consumer market)
19 Marzo 2004
Solution Proposed: MOCA
MOtion Capture with Integrated Accelerometers
• Low-power/ Low-cost components
• Mobile and wearable
• General purpose (angle & inclination)
• Not accurate as traditional
techniques but good enough for our
purpose (gesture recognition)
• Real-time
19 Marzo 2004
25
System architecture
Sensing Unit
Acquisition Unit
Bluetooth,
GPRS, wLAN…
RS232
Lab Prototypes
Mobile Local
Processing Unit
JAVA control application
Localization algorithm
• Flexible system enabling many applications:
– Mobile terminal as target for data acquired by sensors
– Overall system as interaction device with an external
system
19 Marzo 2004
MOCA challenges
• Resource constrained wearable
devices for gesture recognition
pose some design challenges
– Throughput enhancement
– Reduced computing load
– Accuracy optimization
19 Marzo 2004
26
Throughput Enhancement
Tst=Time for sampling, convert and trasmit data
Vx, Vy, Vz voltages from sensing units
Sensing
Unit (SU)
vx
vy
MUX
vz
10 bit A/D internal
converter
UART
~ 100 µs/conversion=> Tst ~ 300/350µs considering 1 SU
• Time increases with number of SU
19 Marzo 2004
Throughput Enhancement
Tst=Time for sampling, convert and transmit data
Vx, Vy, Vz voltages from sensing units
~ 10 µs/conv
16 bit A/D external
converter
vz
Sensing
Unit
~ 100 µs/conv
vy
MUX
10 bit A/D internal
converter
UART
vx
Tst ~ 250 µs => spared 100µs for each Sensing Unit
• Throughput increased
• Minimum cost and power consumption
added
19 Marzo 2004
27
Tracking Algorithm: Limited
Computing Load
u =position vector; a=[ax ay az]
• a=ϋ
u ->∫∫(a)
1. ∫ Increases noise effect on measures
2. Need to periodically reset the system
3. Computational load
• Geometric approach: inclination measure
1. g main contribution to a (steady
- state)
2. Position derived through trigonometric
functions of ax ay az in 1 or more points
3. Examples: 1Dof and 2 DoF
19 Marzo 2004
Both-Near-Sides method
•
•
•
•
2 sensing units for 1 Dof
Accelerometers placed close
around a joint (knee, elbow,
shoulder): distance between
them assumed = 0
Steady
- state- >main
contribution is vector g
Angle θ calculated through:
19 Marzo 2004
θ
ay1
ax1
a1
ay2
a2
ax2
28
2 Dof specialized method
•
•
•
2 DoF algorithm: acceleration value in one
point to measure rotation angles (around 2
indipendent axes)
Only 1 accelerometer for 2 angles
Examples: forearm
A Zero position
must be
established (a
decomposition
of vector g)
g
α
β
g
x y z: reference coordinate
X1 Y1 Z1: rotating coordinate
ax1 ay1 az1: sensor measurement axes
19 Marzo 2004
Accuracy optimization
• Inclination of steady
object:
• When the angle between
g and z is small the
accuracy of the sensing
unit drops. Solution:
exploit accelerometers
redundancy
19 Marzo 2004
29
Hardware – Software Setup
AD Converter
Accelerometers
16 bit, 200 ksps
Serial
Communication
RS232
4 Sensing
Units
115 kbps
Programming
Module
Microcontroller
19 Marzo 2004
Experimental Results (I)
Power Contributors
System
Components
Prototype Power
Consumption in mA
Sensing Unit
12
Acquisition
Board
46
Microcontroller
10
ADC
15
MAX232
15
Total current
absorbed
~60
(6V)
Reduced Number of
Components:
Limited Costs, size,
weight, power
With ordinary batteries (e.g.
750 mAh): 12 hours of
continous operativity
19 Marzo 2004
30
Experimental Results (II)
Accuracy as function of the angle
+/- 3 degree
20 config. in 180°
19 Marzo 2004
Accuracy adequate for
GESTURAL INTERFACES
Angle
Experimental Results (III)
Dynamic Performance
Satisfying Dynamic Performance
( 3 rad/sec ) to guarantee correct
measures for typical human body
movements
Time (in number of samples)
19 Marzo 2004
Sample rate:
2000 sample/sec
31
On-going work
• Recognition of left and right rotation
of the wrist
• 99% of cases distinguished with
accuracy
• Could represent
– Left and right mouse click
– User request of moving left and right in
a Virtual World
19 Marzo 2004
MOCA enhancement
• A wireless sensors
network on the
user body
tranceiver
Sensor (triaxial
accelerometer)
MICRO
antenna
19 Marzo 2004
32
MOCA enhancement:
T-MAC for Wireless Sensor
Networks
• Study of Low
- Power Communication Protocols
among many RF units
• Implementation of -T MAC protocol (a variant of
S
MAC) by Delft University which reduces the
amount of energy wasted on idle listening
• Good when low message rate, insensitivity to
latency
• Future work: Implementation of a low
- power
wireless sensors network facing the challenge of
continuous stream of data from nodes
P
= 90mW
max
19 Marzo 2004
Context Aware Computing
• Localization (IEEE 802.11b,
RF modules, Bluetooth)
• Profiling
19 Marzo 2004
33
Absolute position RF tracking
Characteristics
– Leverages existing Wireless Interfaces
• 802.11 WLAN
• RF (868MHz) low power radio
– Suitable for indoor tracking
– Accuracy: 1-3 meters (under test)
Pmax = 90mW
19 Marzo 2004
Absolute position RF tracking
• Target: localizing a mobile terminal connected in
ad
- hoc network through wireless interface IEEE
802.11b in an indoor environment
• Experimental setup: 4 PDAs (running Linux O.S)
in ad
- hoc network equipped with NICs. One is the
targeted terminal.
• Exploitation of data collected by each PDA
• Technique: exploiting the power level received by
the targeted mobile terminal to estimate the
distance from the others
19 Marzo 2004
34
Experimental results
Study of Room Coverage through Wi-Fi
Y
X
N
E
W
S
Progetto di
Meliota
Alessandro e
Scipioni Marco
19 Marzo 2004
On-going test-bed:
Remote interface + localization
• The real position of each player
affects the state of the game
-> Context aware interfaces
-> Location aware personalized
services. Example: game graphics
visualized on the closest display
w.r.t. the player
19 Marzo 2004
35
“Profiling”…
Many Different
Resources
Many Different Users
19 Marzo 2004
3D API for mobile terminals
• Development of 3D graphic primitives to
visualize simplified virtual world on the cell
phone or PDA
• Example of usage: when the player moves
from a room to another can display the
scene on his mobile terminal
• Optimization for limited resources
hardware (e.g. fixed point arithmetics) to
enhance real-time performance
19 Marzo 2004
36
Thank you
This presentation will be
downloadable soon on the course
Web site:
www-micrel.deis.unibo.it
19 Marzo 2004
37

Outline - MICREL

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