Nessun titolo diapositiva

1
University of Brescia Department of Electronics
for the Automation
A. Flammini, D. Marioli, G. Mazzoleni, E.
Sisinni, A. Taroni
A LOW POWER SOLUTION FOR WIRELESS SENSOR
NETWORKING
Actual wireless sensor scenario
Proposed solution
Power supply / wired link

• On-line Coordinator floor noise monitoring (RSSI)
  in a 2 active channels architecture
• Channel selection
• Few retries for a fast reconnect time
• STAR network topology isochronous time slots
  allocation with ACK (Si)

COORDINATOR
COORDINATOR
COORDINATOR

BPS battery powered sensor

• Low transfer rate (tens bps)
• Low cycle time (tens s)
• Few sensors (Point to Point, Star Topology)
• Several insulated star networks

• Additional transceiver to scan all available
  channels
• Reserved diagnostic time slot (D) where
  coordinator computes channels energy
• Coordinator dynamically sorts channels according
  to their floor noise

Features
Simulations
Experimental Results
Simulations
Test Bench

• Channels divided in 2 groups
• Selection of CC (Clear Channel), BC (Backup
  Channel)
• No data from more than 50 of sensors ? BC ? CC
• Filtering of noise estimation

802.15.4 Coordinator
Coordinator
802.15.4 Sensor
1.5m
LeCroy LT374
1.5m
Ch BC
Rshunt1.5O
Tek RSA3408A
Sniffer
INA110 G100
Sensor
WUSB Coordinator
WUSB Sensor

• Five retransmission in case of no ACK 2 attempts
  on CC plus 1 retransmission on BC then it waits
  for a variable time before to retry again on BC
  and finally on CC
• BC is free ? CC ? BC
• Rebinding procedure when failing condition
  remains for more than 2 cycles

CC ? BC

• WUSB
• RF section power consumption (_at_3.3V)
• TX 69mA, RX60mA
• Sleep µA, Idle 2.5mA

• 802.15.4
• RF section power consumption (_at_3.3V)
• TX 29mA, RX33mA
• Sleep µA, Idle 1mA

N

• Performances evaluation varying floor noise FN,
  burst number BN and burst length BL
• Comparison between the proposed solution and
  standard approach
• Index of merit based on Cost where W represents
  weight of retransmissions (W 1) and rebinding
  procedures (W26)

Simulated Traffic channel occupation
Simulations
802.15.4 Coordinator RF consumption 802.15.4
Sensor RF consumption

• Tx power 3 dBm, Transfer rate 250kbps
• Data payload 100 bytes , ACK 5 bytes
• Duty cycle 48

M Number of sensors, N Simulation steps, W
Consumption weight
Power spectrum estimation
Power spectrum and spectrogram as measured by RSA
3408A

RSSI as evaluated by RF transceivers

BN 10, BL 2000, N 105, M10
FN 0.2 , BL 2000, N 105, M10
FN 0.2 , BN 10, N 105, M10
Email alessandra.flammini,giuseppe.mazzoleni,dan
iele.marioli,emiliano.sisinni,andrea.taroni_at_ing.u
nibs.it Web Site http//www.ing.unibs.it/wsnla
b/