exscal report anish arora the exscal team june 28, 2004 anish arora the exscal team june 28, 2004
TRANSCRIPT
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ExScal Report
Anish AroraAnish Arora
The ExScal TeamThe ExScal Team
June 28, 2004June 28, 2004
Anish AroraAnish Arora
The ExScal TeamThe ExScal Team
June 28, 2004June 28, 2004
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Outline
• Requirements and scenarios
• Architecture• Topology: Tiers 1 & 2
• Hardware components• XSM & its acoustic, PIR, magnetometer sensing hardware
• Stargate & its GPS support; power
• Software components• Reprogramming
• Messaging at Tiers 1 and 2
• Integration status
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Outline of ExScal breakout session
• Site and logistics• Deployment• Timeline
• Xsm schedule
• Workplan
• Metrics• Process• Monitoring & Management• Simulation & Testbed• Beyond extreme scaling:
• Other proposed ExScal experiments for December ?
• What to measure ?
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Requirements
• Quick, high confidence detection & classification of multiple intruder types over long “linear” region
• Fine-grain localization of intruders initially
• Bounded-uncertainty tracking of intruders subsequently
• Concurrent tracking of small number of separated intruders
(or intruder groups)
• Efficient control/maintenance, especially reprogramming,
localization, health monitoring
• Reliable, extended operation (over a fortnight)
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Sample scenarios
Intruding persons arrive by boat, enter and cross lines• (pir) detection, classification, and fine-grain localization
Persons run through the line (a 10K event!)• coarse-grain (bounded uncertainty) tracking• monitor line health
ATV weaves across line• (acoustic) detection, classification, and fine-grain localization
Car/bus traverse road• coarse-grain tracking; (magnetometer) classification based on
initial line crossing
Visualize network health/performance statistics
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Chosen topology wrt to scenario requirements: Grid
• Thick line allows detection & classification w.h.p. as intruders enter the protected region; also allows fine grain intruder localization
• Grid of thin lines allows bounded uncertainty tracking
Thick Entry Line
A S S E T
10 km
500 m
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Tier 1 (XSM) topology
• Detection: Moving intruder detected by at least 10 PIRs
• Classification: Car detected by ≥5 magnetometers
• Tracking: Car traveling at 40 km/hr will be detected for >4 seconds
• Fault-tolerant coverage:
detection is tolerant to crash failure of <7 motes in a contiguous region
classification is tolerant to crash failure of <4 motes in a contiguous region
higher #failures tolerated if crash failures are uniform
… … … … …
180 m
9 m
9 m
4.5 m
36 m
4.5 m
90 m
• # XSMs per Tier2 node ≤50
• each XSM has >12 comm. neighbors (assuming inner band radius of 20m)
• # of XSM hops to Tier2 node ≤4
• separation 91m
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Tier 2 (Stargate) topology
A S S E T
9,720m
90 m
Base Station4,860m 4,860m
16 m
180 m
180 m
180 m
360 m180
m
Path length
• # XSM hops to supernode on thick (thin) line is ≤4 (5)
• # Stargate hops to basestation is ≤20 assuming comm. range of 300m
Fault-tolerant coverage:
• thick (thin) lines tolerate contiguous failure of ≥9 (2) Stargates
• more if uniform
275 stargates
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XSM design considerations
• Improve detection range
• Improve lifetime (previously 3-4 days)
low latency wakeup to support continuous passive vigilance
• Lower cost
• Reliability: deal with 10K nodes with incorrect program
• Fix radio anisotropic radiation and impedance mismatch
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Main changes over Mica2:• Improved sensing, actuation:
added PIR
integrated magnetometer set/reset; fewer ferromagnetic components & their distance to mag. is more
adjustable frequency sounder
• Low-power operation: wakeup circuits for PIR & acoustic
programmable LPF&HPF (acoustic)
• Lower-latency on mag. circuit
• Grenade timer added for reliability
• One-touch operation USER, RESET switches
• Centered antenna, impedance matched to deal with irregular RF
XSM
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Low-power wakeup concept
• Measure signal statistics
• Compute filter cutoffs and signal thresholds
• Program filters and comparator thresholds
• Turn off processor and radio
• Leave signal conditioning circuit running
• Real events and false alarms wakeup MCU
• Perform more complex signal processing in SW
• Reject false alarms
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XSM enclosure
3” x 3” x 3”
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XSM power management
• Energy: 1700 mAhr (85% of 2000 mAhr at 2.2V)
• Network reprogramming: 128 kB → 1 mAhr
• Option for 14 day lifetime:
Partially active ≤ 2 mAhr spent in sleep mode ≤ 20 mAhr spent in reprogramming 84 hours of active lifetime remaining → 6
hours of active life per day for 14 days
Low-power radio mode (35.5% duty cycle, 19 pkt/s)
17mAhr in active mode → 7 hours of active life per day for 14 days
Put CPU to sleep during sensing
Other approaches for reducing power consumption in active mode
• Power management built-in TinyOS Use HPLPowerManagement and Timer modules
Module Active Sleep
CPU 8mA 10 A
Radio 8mA, 16mA (Tx)
1 A
Radio (35.5% duty cycle)
3mA, 12mA (Tx)
2 A
Flash 15mA (write)
2 A
Sensors 4 mA 8 A
Total 20 mA (on average)
40 A
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Tier 2 (Stargate) nodes
CPU: Stargate with Mica2
Comm: SMC2532 HighPower (23dBm) 802.11 card
GPS: TripNAV TN200, WAAS Accuracy~3m
Antenna: 9 dBi collinear omnidirectional antenna
Packaging:Waterproof Stargate Enclosure with
integrated Antenna Mast and Base
Battery: Sealed Lead Acid Battery (105Ah)
Life: Idle Stargate + 802.11 Card: 350 mA
14 Days/12 Hour Network Access: 60 Ah
45 Ah Reserve for Compute + TX
OS: v7.1
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Wireless link performance
Log-distance path loss model
Experiment overview:
• Open grass (6”) field at OSU Airport
• Antenna height: 4’ (120 cm)
• Distance: 100 - 400 m
• Measurements: RSSI reported by card
for 200 packets
at Max Power level &
fixed rate at 1Mbit/sec
Pr(d) Pr (d0) 10 log(d /d0)
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Wireless link performance
Log-distance path loss model
Pr(d) Pr (d0) 10 log(d /d0)
Receiver sensitivity8% PER at -89dBm
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Wireless link performance
Time variation of received signal strength at 400m
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Power management
• Radio consumes 60% of the power of Stargate (>200mA out of
350mA)
• Wakeup on wireless traffic will not be supported for 802.11
• 10 second deadline over 20 hops to Tier 3
fast powercycling of radios requires firmware modification
wireless connections at Tier 2 up continuously
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Status: • first release integrated onto XSM; used
in April IPT demo• characterization & calibration of old XSM
acoustic hardware
Concept:
• energy detector with sliding median
filters for tracking mean & variance of
background noise
Typically range 10-15m:• SUV@20mph on grass, higher on asphalt• good impulsive noise rejection• reduced sensitivity for high background
noise• wind causes anisotropic, time-varying range
Acoustic detector (MITRE)
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Acoustic detector: Improvements
1G:• add AGC to detector• use extra 2-bits of accuracy• band-pass median filter• 8x increase in sensitivity
range increases by
1.5 G:• in quiet environments, signals
drop below 1 ADC unit• will use quantification aware
point estimator• allows for stochastic
resonance or dithering
8
10-3
10-2
10-1
100
101
10-3
10-2
10-1
100
Quantization Estemator (N = 128)
Sigma in A2D Units
Sta
ndard
Devation o
f E
ste
mation in A
2D
Units
Meansqrt(1/12/N)Mediansqrt(1/4/N)Quant MLEQuant Mediansqrt(1/2) / N
100
101
102
103
10-4
10-3
10-2
10-1
100
Law of Large Numbers (sigma = 0.010000)
N
Sta
ndard
Devation o
f E
ste
mato
r
Meansqrt(1/12/N)Mediansqrt(1/4/N)Quant MLEQuant Mediansqrt(1/2) / N
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Acoustic detector: 2G
Targets-not-of-interest:
• as range grows, number of targets-not-of-interest grows
birds, airplanes, wind tree creek, people talking, etc.
especially acute in urban settings
• to do much better than 1G must do partial classification
probably the real limit on range, not sensitivity
i.e., address targets not of interest problem
Proposed Method:
• do low resolution FFT
• fit simple templates to spectrum a car is flat from 100 Hz to 2K
Hz (approx.) a bus is bi-modal an ATV is low-frequency a bird is very narrow band speech is tonal & mid-band
• use template match as detection statistic
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Performance• good SNR observed
so far…
• should support long-range,
low-false alarm detection
PIR detector
human 3 crossings @ 35 ft
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
2 S/divPDF of NoiseKurtosis = 2.97 Concepts
• Sensor & signal conditioning hardware• ADC• PIR Driver (ADC, Wakeup)• Sampling• Long-term moving and 2 computation
• Decide H = H0 if x ≤ , H1 if x > where
= + and is a function of PFA
• Apply digital hysteresis to H
xS N
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Localization
Routing
Monitoring
messaging
Time sync
Network prog Power man
Application
node locations
location timestampsof events
failure info
Reliable Comm
Other Tier 1 “foundation” components
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Messaging at Tier 1
• Substantial performance improvement since last year
• Grid Routing enhancements: reduced # of potential parents (only motes that are closer to
supernode) no inversion
load balancing of parents: switch parent when beacon from potential parent received fast recovery in case of failure
broadcast protocol now piggybacks network parameters in beacons
each mote has primary & secondary supernodes to tolerate supernode failure
• Reliable Comm enhancements
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Network testbed
• 7 * 7 grid of MICA2 motes in 3-4 inches tall grass field
Base station
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Application traffic (trace driven)
• Car moving across the network from left to right at a speed of 15 MPH
• A mote generates a “start” message at the beginning of an event; the mote generates an “stop” message at the end of the event
• All messages are sent to the base station, which performs higher-level detection & classification
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Application trace (contd.)
• Distribution of packet generation
• Highest burst rate = 14.07 packets/sec exceeds limit of BMAC in multi-hop networks ~42.93/4 =
10.73 packets/sec (note: even an ideal MAC only gives ¼ throughput in the case of multi-hop)
• Optimal event goodput: 6.66 packets/sec
0 5 10 150
20
40
60
80
100
Time (seconds)
The
num
ber
of p
acke
ts g
ener
ated
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Exscal GR & RC (up to 2 retransmissions)
Average delivery ratio = 98.8%
up from 46.5% last year
0.95
1
1
1
1
1
1
1
1
1
1
0.95
0.95
1
1
1
1
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0.95
1
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1
0.95
1
1
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1
0.9
1
1
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0.9
1
0.95
0.95
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Exscal GR & RC: distribution of packet reception
0 2 4 6 8 10 12 14 160
10
20
30
40
50
60
70
80
90
100
Time (seconds)
The
num
ber
of u
niqu
e pa
cket
s re
ceiv
ed
RT = 0RT = 1RT = 2
Max. event goodput: 6.37 packets/sec
(close to optimal goodput: 6.66 packets/sec)
Average delay: 1.31 seconds
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Distribution of packet generation and reception
0 5 10 15 20 25 30 350
10
20
30
40
50
60
70
80
90
100
Time (seconds)
The
num
ber
of u
niqu
e pa
cket
s re
ceiv
ed
Traffic traceExscal version GR & RCLiTes version GR & RC
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Network Programming: Deluge (UCB)
• Reliable Pipelined Epidemic Distribution of series of pages Robust to lossy or asymmetric links Very low maintenance bandwidth
• Page Advertise, Request/Fix, Xfer Density-aware suppression and snoop on each
• Packet CRC + Page CRC
• 159 Byte memory footprint
• Packed image (no 64k xnp limit)
• Multiple Program images
• Extensive simulation of dissemination Alg. and many variants
• Tested extensively on 77 nodes
• Simulated on >1,000 nodes in EXSCAL configuration with multiple sources
• 4 mins for 1-hop 33k image to 33 nodes
• Command line host tools
flash
…
Maintain
Request
Transmit
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Localization
Routing
messaging
Time sync
Monitoring-Man.
Data aggreg
node locations
Tier2 architecture
Network prog
Tier1-Loc.
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Messaging at Tier 2
• First implementations tested in both testbed and simulations
• Three contexts: Unicast
Preliminary experimental results
Stream Broadcast ns2 simulation results
Single Packet Broadcast Preliminary experimental results
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Indoor experimental testbed
2 4 6 8 10 12 140
10
20
30
40
50
60
70
80
90
100
The distance (inches)
Link
relia
bilit
y (%
)
• Indoor table-top with 15 Stargates
• Radio: SMC IEEE802.11b card without antenna
• Topology 3 X 5 grid 4 inches separation
Link reliability based on ping
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Unicast routing
• Low power consumption
• Alternate path routing on link failure
• No packet losses
• No periodic beaconing
• Multiple neighbors can be chosen as next hop node
• Exploit:
MAC failure events: iwevent feedback
Buffer failure event: Emstar feedback
Goals Design Principles
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Unicast protocol
• Learn information about neighbors during “network initialization” location of neighbor identity of neighbor reliability on link to neighbor
• Use greedy packet forwarding ignore neighbors with low reliability pick up next-hop that minimizes distance to destination
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Packet delivery percentage
• Current unicast protocol mechanisms for detecting node & link failure identified but
not yet implemented each packet is simply transmitted twice as otherwise end-to-
end reliability is around 60%• For transmission from source to diagonally opposite sink
• Each node sends 1 packet every 10 seconds Four farthest nodes sending packets to the sink
Average packet delivery percentage = 96.88% All nodes sending packet
Average packet delivery percentage = 97.9%
Inter-packet interval (seconds)
10 5 2
Packet delivery 93.91% 100% 98.90%
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Unicast: plans
• Implement techniques for handling node and link failure MAC and buffer losses
• Experiment with various metrics for selecting next-hop node
• Test on larger topologies
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Broadcast for reliable reprogramming
• Minimize number of data transmissions
• Minimize contention between new data transmissions and old data re-transmissions
• Use a minimum connected dominating subset (MCDS) of nodes for data transmissions
• Phase I for streaming new data and phase II for recovery
Goals Design Principles
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Reliable broadcast protocol
• Pre-determined parent child relationship Between MCDS nodes Between non-MCDS nodes and MCDS nodes
• Phase I (Only MCDS nodes participate) Tier-3 node streams packets at a fixed streaming rate Each node broadcasts new data packets, with following piggybacked
information a bit-vector with 1’s for the packets it has received total number of packets
Each node estimates the time at which phase I ends
• Phase II (All nodes participate) Periodically unicast bit-vector to parent if packets are missing Unicast data to children requesting recovery
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Ns2 simulation results for 219 nodes: Latency
• 128 51-byte packets in the final 219 node stargate topology
• Finding the right streaming period to minimize latency
• Disk model, contention, capture effects, not link loss
Latency
02468
1012141618
0.012 0.013 0.014 0.015 0.016 0.017
Streaming Period
Tra
nm
issi
on
Tim
e
Recovery
Streaming
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Ns2 simulation results for 219 nodes: reliability
Reliability
121122123124125126127128129
0.012 0.013 0.014 0.015 0.016 0.017
Streaming Period
Mes
sag
es R
ecei
ved
Recovery
Streaming
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Overhead
0
5000
10000
15000
20000
25000
0.012 0.013 0.014 0.015 0.016 0.017
Streaming Period
Mes
sage
s Tr
ansm
itted
Recovery
Streaming
Ns2 simulation results for 219 nodes: overhead
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Reliable broadcast plans
• Simulate lossy channel So far losses are only due to collisions or capture
effects at MAC
• Extend the protocol dynamic streaming-rate computation mechanisms to deal with node failures k-connected structure instead of 1-connected
• Experiment with stargates
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Single packet broadcast: Motivation
• Reliably distributing commands Start the network Put nodes in doze mode Put nodes in fully awake mode Commands for T1 nodes
• Reliably distributing parameters New transmit power New data rate Parameters for T1 networks
• Reliably querying the T2 nodes How many T2 nodes are up? How many T2 nodes got the last broadcast successfully? Status report of T1 nodes
Is T1 localization over? How many T1 nodes are up?
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Single packet broadcast
• Highly Robust: reliable delivery and ack
• Minimize number of overhead messages
• Minimize interference between request and response messages
• Periodic request and response messages
• Use aggregation of responses
• Use separate phases for request and response messages
Goals Design Principles
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Single packet broadcast(Two Phase Protocol)
• Phase I: inform T2 nodes; create a structure for phase II T3 node sends k periodic beacons Each T2 node on hearing the first beacon starts sending k periodic
beacons Each T2 node estimates the end of first phase Each T2 node registers with a parent to which it will send
aggregated response
• Phase II: aggregate responses from T2 nodes If node is a leaf node
Send periodic responses to parent
else Aggregate responses from children and send periodically to parent
Parent acknowledges children for each response Child stops sending response on hearing ACK
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Single packet broadcast: Status and plans
• Status Experiments on 15-node indoor grid network
A preliminary version of the protocol has been testedo Response is transmitted only once (not periodically)o Phase II is merged with Phase I
Beacon period: 10 sec Response message period sent only at 5 sec intervals
With aggregation (average of 5 runs) 13 out of 15 nodes are heard back in 14.5 sec
Without aggregation (average of 5 runs) 9 out of 15 nodes are heard back in 11.5 sec Slightly faster but low reliability
• Plans Experiments with the more robust protocol Experiments with larger topologies
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12 hand-placed XSMs known
locations
w/ active acoustic sensing
2 stargates for “left” & “right” 6
XSMs
System can:
• detect intruders (including golf-cart, car, SUV, tractor, plane)
• visualize intruder on Tier 3 node
• classify some intruder types, using multi-modal distributed influence fields
Standalone reprogramming demo : 50 nodes
Standalone localization demo (46nodes, improved June 15th)
April 30th demo layout & features
50 m
~10 m
~10 m
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Integration status
• Sensing signal chains Mag.(2-3m for metal-bearing humans, 5-7m for vehicles) Acoustic (15-25m for vehicles) PIR (10m for humans)
• Tier 1 network services GridRouting ReliableComm TimeSync (modified version) Deluge (Multihop reprogramming) Suspend application during reprogramming
• Tier 2 Mica2 “transceiver”: talks to Emstar “hostmoted” component on Stargate
Emstar “routing” component for application to communicate w/ Tier 3 node