Bandwidth Allocation in Sense-and-Respond Systems
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Transcript of Bandwidth Allocation in Sense-and-Respond Systems
Bandwidth Allocation in Bandwidth Allocation in Sense-and-Respond Sense-and-Respond
SystemsSystems
Vincenzo LiberatoreVincenzo Liberatore
Research supported in part by NSF CCR-0329910, Department of CommerceTOP 39-60-04003, NASA NNC04AA12A, and an OhioICE training grant.
Sense-And-RespondSense-And-Respond
Computing in the Computing in the physical worldphysical world
ComponentsComponents Sensors, actuatorsSensors, actuators ControllersControllers NetworksNetworks
Sense-and-RespondSense-and-Respond
EnablesEnables Industrial automation [BIndustrial automation [BLL04]04] Distributed instrumentation [ACRKNDistributed instrumentation [ACRKNLL03]03] Unmanned vehicles [Unmanned vehicles [LLNB03]NB03] Home robotics [NNHome robotics [NNLL02]02] Distributed virtual environments [Distributed virtual environments [LLCCK05]CCK05] Power distribution [P05]Power distribution [P05] Building structure control [SLT05]Building structure control [SLT05]
Merge cyber- and physical- worldsMerge cyber- and physical- worlds Networked control and tele-epistemology [G01]Networked control and tele-epistemology [G01]
Sensor networksSensor networks Not necessarily wireless or energy constrainedNot necessarily wireless or energy constrained One component of sense-actuator networksOne component of sense-actuator networks
CharacteristicsCharacteristics Heterogeneous collection of networked sensors, Heterogeneous collection of networked sensors,
actuators, controllersactuators, controllers Power Power
Often plentiful, sometimes limitedOften plentiful, sometimes limited Communication Communication
Often wired, sometimes low-bandwidth wirelessOften wired, sometimes low-bandwidth wireless Critical requirements: Critical requirements:
SafetySafetyStabilityStabilityDependabilityDependabilityRobustnessRobustnessQoSQoSScalabilityScalabilityAdaptabilityAdaptability
Information FlowInformation Flow
FlowFlow Sensor dataSensor data Remote controllerRemote controller Control packetsControl packets
Timely deliveryTimely delivery StabilityStability SafetySafety PerformancePerformance
OutlineOutline
OutlineOutline Introduction to Sense-and-RespondIntroduction to Sense-and-Respond Bandwidth AllocationBandwidth Allocation Future of Cyber-Physical InfrastructureFuture of Cyber-Physical Infrastructure
WarningWarning Most EE-oriented talk I could possibly giveMost EE-oriented talk I could possibly give Avoid redundancy with previous talksAvoid redundancy with previous talks
Bandwidth AllocationBandwidth Allocation
Bandwidth AllocationBandwidth Allocation
DefinitionDefinition Multiple sense-and-respond Multiple sense-and-respond
flowsflows Contention for network Contention for network
bandwidthbandwidth
DesiderataDesiderata Stability and performance of Stability and performance of
control systemscontrol systemsMust account for physicsMust account for physics
Efficiency and fairnessEfficiency and fairness Fully distributed, Fully distributed,
asynchronous, and scalableasynchronous, and scalable Dynamic and self-Dynamic and self-
reconfigurablereconfigurable
Control and NetworksControl and Networks
Control Control overover Networks (C Networks (Cover over N)N) NCSs, DCSs, SANETs, CPs, …NCSs, DCSs, SANETs, CPs, …
Control Control ofof Networks (C Networks (Cof of N)N) Efficient BW allocationEfficient BW allocation
Regulate the packet injection rateRegulate the packet injection rate
““CCof of N” scheme to better serve “CN” scheme to better serve “Cover over N” N”
Control Control ofof Networks Networks
A bandwidth allocation schemeA bandwidth allocation scheme
Formulate the scheme as a Control Formulate the scheme as a Control problemproblem
Control systems regulate sending rate Control systems regulate sending rate based on congestion signal fed back from based on congestion signal fed back from the networkthe network
Sampling Rate and Sampling Rate and Network CongestionNetwork Congestion
h=1/r
l1 l2
Problem FormulationProblem Formulation
Define a utility fn Define a utility fn UU((rr) ) that isthat is Monotonically increasingMonotonically increasing Strictly concaveStrictly concave Defined for Defined for rr ≥ ≥ rrminmin
Optimization formulationOptimization formulation
( )
min,
max ( )
s.t. , 1,...,
and
i ii
i li l
i i
U r
r C l L
r r
S
Distributed ImplementationDistributed Implementation
Two independent algorithmsTwo independent algorithms End-systems (plants) algorithm End-systems (plants) algorithm Router algorithm (later on)Router algorithm (later on)
Plant ControllerRouter
max
min
1( ) 1 ' ( )r
rt tp pr h U
p p
p
NCS-AQM Control LoopNCS-AQM Control Loop
tf
q(t)f(q(t))q`=Σr(t) - C
p(t)
tb
1( ) ' ( )r p U p
Plant Queue
sdBes
QueueController
G(s)
Queue Controller Queue Controller G(s)G(s)
Proportional (P) Controller Proportional (P) Controller GGPP(s) = k(s) = kpp
Proportional-Integral (PI) ControllerProportional-Integral (PI) Controller GGPIPI(s) = k(s) = kpp ++ k kii//ss
q(s)G(s) P(s)
q0
+ _e u
Determination ofDetermination of k kpp andand k kii
Stability region in the Stability region in the kkii–k–kp p planeplane Stabilizes the NCS-AQM closed-loop system for Stabilizes the NCS-AQM closed-loop system for
delays less or equal delays less or equal dd
Analysis of quasi-polynomials, Analysis of quasi-polynomials, f(s,ef(s,ess))
Simulations & ResultsSimulations & Results
50 Plants:
( ) ( )dx
ax t bu tdt
/ ( ) a ra bKU r e
a
min ln
ar
bK abK a
()
((
))j
ju
tK
Rx
t
[Branicky et al. 2002]
[Zhang et al. 2001]
Simulations & Results (cont.)Simulations & Results (cont.)
PI¤
P¤
Related WorkRelated Work
Congestion Control Congestion Control Primarily addresses elastic flowsPrimarily addresses elastic flows Active Queue Management (AQM)Active Queue Management (AQM) Utility maximization and controllers often viewed as Utility maximization and controllers often viewed as
alternative approachesalternative approaches
Multi-media congestion controlMulti-media congestion control E.g., Equation-basedE.g., Equation-based Smooth rate variationSmooth rate variation No physically relevant utilityNo physically relevant utility
Time-scales Time-scales Approach to define time-varying utility functionsApproach to define time-varying utility functions ““C of N” missingC of N” missing
OutlineOutline
OutlineOutline Introduction to Sense-and-RespondIntroduction to Sense-and-Respond Bandwidth AllocationBandwidth Allocation Future of Cyber-Physical InfrastructureFuture of Cyber-Physical Infrastructure
WarningWarning Most EE-oriented talk I could possibly giveMost EE-oriented talk I could possibly give Avoid redundancy with previous talksAvoid redundancy with previous talks
Cyber-Physical SystemsCyber-Physical Systems
Foundations and Foundations and technologies for rapid and technologies for rapid and reliable development and reliable development and integration of computer-integration of computer-centric physical and centric physical and engineered systemsengineered systems
““Globally virtual, locally Globally virtual, locally physical”physical”
Major NSF initiative Major NSF initiative plannedplanned
Needs and DirectionsNeeds and DirectionsNeeds and DirectionsNeeds and Directions
New CalculusNew CalculusMerge time- and event-based systemsMerge time- and event-based systems
New ToolsNew ToolsE.g., co-simulation for co-designE.g., co-simulation for co-design
New Networks methodsNew Networks methodsBandwidth allocation, play-back buffersBandwidth allocation, play-back buffers
New EducationNew EducationMulti-disciplinary educationMulti-disciplinary education
Telltale sign: New MetricsTelltale sign: New Metrics Network-oriented metricsNetwork-oriented metrics
Delay, jitter, loss rates, bandwidthDelay, jitter, loss rates, bandwidthImpacts physics, but different from physics behaviorImpacts physics, but different from physics behavior
Control-Theoretical metricsControl-Theoretical metricsOvershoot, rise time, settling time, etc.Overshoot, rise time, settling time, etc.Hard to relate to network conditionsHard to relate to network conditions
Multi-disciplinary metricsMulti-disciplinary metricsE.g., plant tracking in terms of network bandwidth allocationE.g., plant tracking in terms of network bandwidth allocation
An E-Model for cyber-physical systems?An E-Model for cyber-physical systems?
ExampleExample
PI¤
P¤
AcknowledgmentsAcknowledgments
StudentsStudents Ahmad al-HammouriAhmad al-Hammouri David RosasDavid Rosas Zakaria Al-QudahZakaria Al-Qudah Huthaifa Al-OmariHuthaifa Al-Omari Nathan WedgeNathan Wedge Qingbo CaiQingbo Cai Prayas AroraPrayas Arora
ColleaguesColleagues Michael S. Branicky Michael S. Branicky Wyatt S. NewmanWyatt S. Newman
ConclusionsConclusions
Sense-and-RespondSense-and-Respond Merge cyber-world and physical worldMerge cyber-world and physical world Critically depends on physical timeCritically depends on physical time
Bandwidth AllocationBandwidth Allocation Control of Networks to aid Control over NetworksControl of Networks to aid Control over Networks Complete characterization of the stability regionComplete characterization of the stability region EvaluationEvaluation Peak detectionPeak detection
Cyber-physical systemsCyber-physical systems
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