> Motivation
> System Evaluation
> System Architecture
RTD 2010X-Sense
Felix Sutton, Bernhard Buchli, Jan BeutelComputer Engineering and Networks Laboratory, ETH Zurich, Switzerland Technische Informatik und Kommunikationsnetze
Computer Engineering and Networks Laboratory
An Ultra-Low Power Wireless Multi-Sensor Interface
> Proposed Solution
REFERENCES: [1] G. U. Gamm, M. Sippel, M. Kostic, L. M. Reindl, "Low-power sensor node with addressable wake-up on-demand capability", International Journal of Sensor Networks, Vol. 11, No. 1, January 2012.
Practical limitations of multiplexed wired sensors: - Inherent fragility of sensor cabling - Restricted sensor placement - Cumbersome installation Damage by wildlife
Rock fall damage
Moisture damage
Cumbersome installation
Wireless Sensor Network
Microcontroller(PIC24F32KA302)
Voltage Regulator
Battery
Sensor Non-Volatile Memory
Power Management
Configuration Interface
Wake-up Radio
Data Radio(TI CC110L)
Antenna Switch
Microcontroller(PIC24F32KA302)
Measurement Request
DataInterface
Data Radio(TI CC115L)
Wake-up Channel
Data Channel
Cluster Node
Cluster-head
GainEnvelope DetectorCorrelator
Serial Data Interface
Real-Time Clock
Control Logic
AS3930 Wake-up ReceiverOOK Demodulator
Z0
Wake-up Radio (Gamm, et al. [1])
Key Features: - Ultra-low power wake-up radio on 434MHz ISM band - Cluster time-synchronization using wake-up radio - Collision-free data transmission using TDMA policy - Periodic sensor sampling and FRAM data storage - Power gating of all microcontroller peripherals - User configurable RTC and measurement period
Cluster node prototype Cluster-head prototype
Data Radio
Antenna Switch
Wake-up Radio
ConfigurationInterface
FRAMVoltage Regulator
Data Radio
Microcontroller
Measurement Request
Data Interface
Microcontroller
Activity Component Duration [s] Power [mW]
MeasuringMicrocontroller
0.04562.4399
Memory 0.1811Wake-up Radio 0.0032
Communicating
Microcontroller
0.3020
2.5092Data Radio 22.1637Memory 0.0195
Wake-up Radio 0.0032
SleepingMicrocontroller
10799.65240.0236
Wake-up Radio 0.0032
LDO Regulator 10800 0.0510Total 0.0785mW
Performance Summary: - Total average power dissipation of 78.5μW - Estimated > 3 years on 1Ah coin cell battery - Communication range up to 14 meters LOS
Summary of power analysis measured at 2.5V(assuming 1 hour measurement interval with a data request every 3 hours).
0 5 10 15 20 25 30 35
10−2
10−1
100
101
102
Time [s]
Pow
er [m
W]
Microcontroller
Data Radio
Non−volatile Memory
Wake−up Radio
Communication(22mW avg., 300ms)
Measurements(2.4mW avg., 45ms)
Microcontroller Sleep: 23μW avg.
Wake-up Radio Active: 3.2μW avg.
Impedance matching analysis
400 405 410 415 420 425 430 435 440 445 450−30
−25
−20
−15
−10
−5
0
Frequency [MHz]
Ret
urn
Loss
[dB
]
PIN = 0 dBm
PIN = −10 dBm
PIN = −20 dBm
PIN = −30 dBm
Wake-up receiver return loss
Hierarchical sensing network provides: - Wireless connectivity for flexible sensor placement - Autonomous operation mitigating fragile sensor cabling - Sensor abstraction for aggregation of sensor data
Cluster-head
Cluster Nodes
readSensor(...)Asynchronous Wake-up Request
Synchronous Data Response