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BEing on Time Saves energY
The BETSY Framework
ΕΚΕΦΕ Δημόκριτος, 23/5/2007
Δημήτριος Βογιατζής
Overview
1.Project overview
2.Summary
3.Project objectives
4.Methodology
5.Framework
6.Conclusions
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BETSY strep project
Sep 2004 – Mar 2007
Participants
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NXP – Netherlands
CSEM - Switzerland
IMEC - Belgium
ISI - Greece
TUK - Germany
Siemens C-Lab - Germany
TU/e - Netherlands
University of Cyprus - Cyprus
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Example of home network
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Example of a hotspot
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BETSY (BEing on Time
Saves energY)
• BETSY aimed to deliver the theory,
models & design methods to make
• trade-offs between
– network & terminal resource consumption
– power consumption of the terminal
– timeliness of the streaming data
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Summary
• BETSY manipulates of video streams on wireless
hand-held devices such that
– hand-held devices seamlessly adapt to fluctuating network
conditions and available terminal resources
– energy consumption for processing the video is reduced
• True multi-media experience the device is required to
– handle trade-offs between the use and consumption of
network and terminal resources such as bandwidth, CPU
time, Buffer space, and power, and
– to guarantee to end-to-end timeliness for the streaming data.
• This leads to the following (next …)
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Summary (cont.)
• Provide an integrated approach to real-time
requirements for dynamic networked
streaming systems
• Define a common resource model that can be
used as an abstraction layer to hide lower
level system parameters from higher level
temporal descriptions and QoS strategies
• Understand the trade-off in energy
consumption at the overall system level &
balance energy consumption over different
sources of energy
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Trade off triangle
• Trade-offs between the use
and consumption of network
& terminal resources such as:
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Bandwidth
CPU time
Buffer space
Power
• Guarantee end-to-end
timeliness for streaming data
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Methodology
• Design & reference implementation of an end-to-end
quality-of-service framework
• Timing model for a top-down approach
• Resource model to calculate the proper distribution of
computing resources: bandwidth & energy
consumption
• Verify timing & resource model  framework
populated by selected components or modules
– Use the framework’s mechanisms to adapt the processing
chain to changes in the resources
• Framework & its components are implemented in a
streaming server and mobile clients
– evaluation scenarios
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BETSY functions
• Functions used by streaming
applications
• Breeze::= is a piece of content,
processed by a sequence of functions
for processing, storing and
communicating data items in an end-toend delivery chain, on which only one
entity is in control
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BETSY functions II
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Capturing
Retrieving
Recording
Encoding
Decoding
Delay buffering
Rendering
Multiplexing
Demultiplexing
Transcoding
Transporting
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Relations between BETSY
functions and data types
•data types are
represented as colored
rectangles
•functions are
represented by the
rounded rectangles
•input and output data
types with arrow from
and to the data types
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Energy Consumption
Modelling
• Desired energy models
– Desired breeze parametersenergy
– for
• Separate functional components
• Complete sub-breeze on one device
– Alternative
• Parameters = f(lower level interm.)
• Intermediate params = f(lower level parm.)
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Battery model
Battery
status
power
Battery
Remaing
life time
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Network Model
# streams
max.packe
t size
bandwidth
Network
Bit rate
per stream
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MPEG-4 stream Model
FR
FS
IP
QP
MPEG-4
Bit Rate
MPEG-4
Quality
Bit rate
PSNR
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Scenario I (Evaluation)
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Composed model I
FR
FS
IP
QP
available
bandwidth
1 stream
max.packe
t size
MPEG-4
Bit Rate
MPEG-4
Quality
Model
Quality
(PSNR)
Encode, Mux,
Transport
required
bandwidth
Network
sufficient
available
bandwidth
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Scenario II Evaluation
PDA
(GUI)
Requested
Remaining Time
(Camera-Param)
Current Param
(Camera)
WLAN-Camera
(battery driven)
Display
Access Point
Battery Status,
FR, FS
Breeze
Media Center (PC)
Breeze’
Change
FR, FS
Current
Meter
Battery High/Low
Switch
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Composed Model II
# streams
(2)
max.packe
t size
raw
bandwidth
QP
IP
FS
Battery
status
FR
Network
Transport, Decode,
Rendering
(PDA)
MPEG-4
Bit Rate
Power
Encode, Mux,
Transport
(Media Center)
MPEG-4
Quality
Model
Battery
bandwidth
per stream
sufficient
bandwidth
Quality
Remaing
life time
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Composition Rules
• To make trade-offs,
– latency, energy, and quality models, have to be
combined into a single all-encompassing model
– The parameters are key to combining the models
– three independent models,
• Latency, Energy, & Quality,
• each functional component, could be combined to a set
of independent models for the entire breeze
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Compositions Rules
• Depending on the intended use of the model the required
models of the parts can be composed into an end-to-end model
• Models represents a set of configurations or tuples of attributes
• The essential ingredients of model composition are
– Cartesian product of tuples when two models are combined freely
(without any constraints).
– combinations matching on selected attributed (like the join of a
relational database). For instance all components have to work with
the same stream and hence share the same values for the FR, FS,
IP and QP parameters.
• IA so-called ’producer-consumer constraint’ expressing the
matching connections between parameters of different models
such as available bandwidth and required bandwidth (Pareto)
optimization after combination and abstracting internal
parameters can be used to reduce the set of candidate
configurations
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Composition Rules (cont.)
FR
FS
IP
QP
%I
Latency
Model
Energy
Model
Quality
Model
Latency
Energy
Quality
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Software framework
GRACE
System
Level
MATRIX
Global
Coordinator
PCES
Resource
Manager
OZONE
System Resource
Manager
Application
Manager
Mode Manager
Subsystem
/ Device /
Application
Level
Resource
Level
Application
Coordinator
Application
Adaptor
Scheduler/Adaptor
Monitor&
Predictor
Monitor&
Predictor
Local Resource
Manager
Order
Manager
Local
Scheduler
Local
Monitor
Controller
Resource
Control
Predictor
Quality Manager
RCE Controller
Resource Manager
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Software frameworks
common characteristics
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Recognize the benefits
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application level adaptation & resource level management
provide a sustained user-level quality of the multimedia flows
Define a hierarchy of control elements based
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structural and temporal scope differences of the controlled
elements
A root element with a global knowledge of the system status
Resource managers / brokers at the base, which
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receive resource allocation commands & enforcing them
Address QoS concepts at all domains,
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Resource-level QoS (for the network and the CPU resources)
Application / video QoS (with the exception of PCES for an
explicitly defined view of the latter)
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Software frameworks
differences
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Design level differences at,
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structure, number, scope & specific behavior of
the intermediate control elements
between the root system-level manager &
resource brokers at the bottom of the hierarchy
Engineering level differences at,
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definition of the details of the interfaces of their
software components
realization of the inter-component
communication mechanisms, local or distributed,
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Ozone Architecture
Application Manager
ApplicationManager : ResourceConsumerController
Mode Manager
ModeManager : ResourceConsumerController
Quality Manager
QualityManager : ResourceConsumerController
RCE
RCEControl :
ResourceConsumerController
RCE Control
One-to-One mapping
RCE
Operation
RCE
Operation
SF1
SF2
RCEOperation :
StreamingFunction
SF3
ResourceManager : ResourceServiceController
Resource Manager
: ResourceService
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Distributed ozone
architecture
TERMINAL1
TERMINAL2
Application Manager
Mode Manager
Terminal Quality Manager
RCE
Terminal Resource Manager
Subnet Quality Manager
NCE
Subnet Resource Manager
Terminal Quality Manager
RCE
Terminal Resource Manager
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Breeze Creation and Control
Signaling (I)
• User instructs the system to create a new breeze from a source
to a number of sink devices, streaming a selected content with a
possible set of preferences (quality, duration).
• User interface translates the user’s input to a createBreeze()
API signal, which actually transfers the request to a previously
discovered BreezeManager in the distributed system.
createBreeze(src, dests[], content, pref)
UI
BM
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Breeze Creation and Control
Signaling (II)
• BreezeManager according to its global view of the system and
its configuration decides on the acceptance of the breeze starts
the creation of the configured elements in the appropriate
devices (createElement() signal), connects them
(connectElements() signal) according to the system
configuration and returns to the user interface a global handle of
the breeze for breeze handling (play(), pause(), stop() and
destroy() signals).
BM
Create(), Connect(),
Set()/Get()/Subscribe()
BM
BM
X
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Breeze Creation and Control
Signaling (III)
• Each element in the control / stream chain of the breeze, on
reception of a connect() signal from the BreezeManager,
invokes its own startup signals which are mainly a number of
get()/set() and subscribe() API calls.
• The control policy which the whole chain implements is then
continuously running through the exchange of variable change
events and set() / get() signals.
Event()
Controller
Function
Set() / Get()
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Breeze Control
Controller
Stream Data
Function
Function
Control Data
Resource mappings
RService
Resource
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Core Component Libraries
• Components built in the framework:
– BreezeChain and StreamingFunction interfaces for :
• the VLC streaming framework (www.videolan.org)
• the AXIS camera
– Resource and ResourceService interfaces for:
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the CPU and the OS scheduler
the network interface and the protocol stack
the memory and the stream buffers
the battery and the power consumption
– Access and protocol interfaces for:
• UPnP discovery, signaling and control
• Raw TCP/UDP signaling and control
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System-level Component Libraries
• Components built with the framework for
demonstration, validation and testing reasons:
– A typical breeze manager
– A set of breeze controllers implementing various control
policies
– A pareto modeling element
– A set of low level resource modeling elements
– A main user interface controller for device discovery,
enumeration and breeze management
– A resource monitoring infrastructure and display
– A resource knob monitoring and control panel
– A breeze knob monitoring and control panel
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Main user interface
• Enumerate existing devices, breezes and elements
• Create and destroy breezes
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Breeze knob panel
• Monitor controller decisions and breeze adaptations
• Freely control any of the available knobs
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Breeze knob panel
• Monitor controller decisions and breeze adaptations
• Freely control any of the available knobs
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Resource knob panel
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Monitor resource status, controller decisions and resource adaptations
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Freely control any of the available knobs
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Resource consumption panel
• Monitor resource consumption status as a result of
controller decisions and various knob adaptations
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Controller Example
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Controller (CTLS1) connected to the wireless LAN concrete resource
interface (input), to a Pareto modeling element (ParetoM1) and to the
encoding function of the source breeze chain (output)
Based on the existence of an automatic rate fallback WLAN driver
ParetoM1
Controller
Encode
WLAN
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Controller Example
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Signaling of CTLS1:
– Receives an event for each raw bandwidth change, which actually captures
a very fast change in the link quality.
– Consults the pareto model to get the best configuration set for the encoder
(FS, FR, IP, QP)
– Adapts the encoding function by applying the new configuration set
2
ParetoM1
Controller
1
3
Encode
WLAN
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Framework overview
• software framework for QoS and resource control in and end-toend stream delivery chain
• Provides the infrastructure for implementations of functional
entities/devices with the necessary interfaces to control the
streaming and device resource parameters
• Provides the means for end to end performance and resource
consumption assessments for different trade-off handling and
control policies
• Abstracts the main building components needed by the control
policies making extensive reuse possible and guaranteeing
interoperability between devices of different vendors
• Raises the domain of the problem hiding all technical details of
distribution and inter-component communication, allowing the
engineer to concentrate on the control policy and the trade-offs
under study
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Thank you
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Wireless Network Savings
• Resource consumption cost for each
resource parameter over each resource
• Important: study resource consumption
behaviour of the transport function
• Time, Energy: Primary resources
– <= abstract resources: processing, storage,
bandwidth
• We have energy costs of a stream transition=
f(costs of protocol processing, data
packetisation, transmission)
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Configurations, 100 kbit/s
([IP], [QP], [FS], [FR], PSNR, bit rate)
([IP8], [QP10], [QCIF], [12.5], 26.1, 24.9),
([IP16], [QP5], [QCIF], [12.5], 26.8, 47.7),
([IP16], [QP10], [CIF], [25], 28.6, 95.6),
([IP16], [QP10], [QCIF], [12.5], 26.1, 18.4),
([IP16], [QP15], [CIF], [25], 27.8, 67.8),
([IP16], [QP15], [CIF], [12.5], 26.2, 41.3),
([IP16], [QP15], [QCIF], [12.5], 25.6, 12.3),
([IP32], [QP5], [QCIF], [12.5], 26.8, 41.3),
([IP32], [QP10], [CIF], [25], 28.5, 77.6),
([IP32], [QP10], [QCIF], [12.5], 26.1, 15.2),
([IP32], [QP10], [QCIF], [5], 24.3, 9.3),
([IP32], [QP15], [CIF], [25], 27.8, 54.8),
([IP32], [QP15], [CIF], [12.5], 26.2, 35.0),
([IP32], [QP15], [QCIF], [12.5], 25.6, 10.1),
([IP32], [QP15], [QCIF], [5], 24.1, 6.08)}
highest PSNR
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Overview of Video Coding
I-frames (Intra): exploit spatial correlation within the frame
P-frames (Predictive): temporal correlation (prediction from
previous frames)
Higher compression efficiency
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Impact of Intra/Predictive on Error
Propagation
Concealment of lost data:
for example copy from
previous frame
Error propagates as later frames
predict from wrong data
Stop error propagation by inserting
Intra information (no reference to
previous frames)
Lower compression efficiency of Intra -> Bit rate overhead
Tradeoff error robustness and coding efficiency
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Intra Frame insertion vs Gradual
Intra Refreshment
Using Periodical
Intra frames
Updating in every
frame an Intra portion
Intra Period T = 6
%Intra = 16%
%Intra information has a big impact on the Quality-Rate
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modeling under network errors