As part of your wireless sensor networks course at UC Irvine, my colleagues and I from the Masters in Embedded and Cyber-physical systems presented our research. We conducted field tests using ESP-8266 devices and the painless mesh library. This test was conducted in an outdoor environment to understand range and path loss function estimation. Researchers- Ashish Anand, Pratyush Mangalakattu and Sagar Patel.

1. Ashish Anand
Pratyush Mangalakattu
Sagar Patel
Implementation and Analysis of
Wireless Mesh Network Using
ESP8266
1

2. 2
INTRODUCTION
How?
How the mesh
system was created
1
Theory
Important theory
regarding mesh
networks
2
On FieldTesting
Testing out the mesh
in real world
3
What we
learned
Key takeaways from
field testing
4
Conclusion
What we learned
from the project
5

3. 3
PAINLESS MESH LIBRARY
 An Open-Source library created by BlackEdder
 Self-Organizing and repairing network
 Accurate time synchronization
 All nodes are equal
 Network uses a star topology
 Messages passed around in JSON format

4. 4
NETWORK LAYOUT
 Every node acts as Access Point for the
other node
 Every Node knows the complete topology.
Node sync is done:
 Periodically
 Connection is made or lost
 Time synchronization with a precision
better than 10us
 Broadcast and Single message is possible

5. 5
PROTOCOL EXPLAINED FURTHER
 Node MAC address as identifier
 TCP based connection
 Time syncing
𝑜𝑓𝑓𝑠𝑒𝑡 =
𝑡1−𝑡0
2
+
𝑡2−𝑡3
2
 Repeated until calculated offset is less
than 10 us
 Repeated every 10 minutes
Adopter Recipient
𝑡0
𝑡3
𝑡1
𝑡2

6. 6
RSSI AS THE DRIVING PARAMETER
 RSSI as driving factor for node connection
 Measured at varying distances
 Performance derived using RSSI

7. 7
PATH-LOSS FUNCTION
𝑃𝐿 𝑑𝐵 = 10 log10
𝑃𝑡
𝑃𝑟
𝑑𝐵
Equation I

8. 8
CLASSIFICATION OF MESH NETWORK
 Based on NetworkTopology
 Flat (Flooding, SPIN, Direct Diffusion, DistanceVector Routing, Ad-Hoc On-demand DV)
 Hierarchical (LEACH)
 Routing Discovery
 Reactive
 Proactive
 Painless mesh uses Proactive Ad-Hoc On-demand DistanceVector Routing Protocol.

9. 9
RESEARCH METHODOLOGY
 Deploy ESP8266 in urban environment
 Plan deployment using Google Maps
 Measurement of RSSI with real time
monitoring

10. 10
OBSERVATIONS
Sl. No. Distance (m) RSSI Path Loss TX Power (dB) RX Power (dB) Sensitivity (dB) Radius
1 10 -68 82 14 0.003 -72 1.221
2 25 -72 86 14 0.002 -72 1
3 50 -78 92 14 0.001 -72 0.74
4 100 -88 102 14 0.0005 -72 0.44
5 150 -90 104 14 0.0005 -72 0.4
Outdoor Values Considering LOS and Free Space (Deterministic channel model)
 RSSI measured on-field
 Path Loss = TX - RSSI
Taken from Datasheet On-field measurements Derived from equation I(Slide #7)

11. 11
RADIUS (NODE CONNECTIONS PROBABILITY)
N Sl. No. Path Loss TX Power (dB) Sensitivity (dB) Radius
1 82 14 -72 1.221
2 86 14 -72 1
3 92 14 -72 0.74
4 102 14 -72 0.44
5 104 14 -72 0.4
𝑟𝑎𝑑𝑖𝑢𝑠 < 𝑒(𝑃𝑡−𝛾−𝐿0)/10𝑛
𝑃𝑡 – Transmitted power
𝛾 – Receiver sensitivity
𝐿0 – Path loss at 𝑑0
𝑛 – Path-loss exponent
Taken from Datasheet Derived from Equation I Derived from equation II
Equation II

12. 12
ON-FIELD EXPERIENCE
 The mesh network behaved
differently in a densely traffic
environment area vs a less dense traffic
area.
 Painless Mesh was unreliable for
long distances(>150m). Even with
14.5 dbm transmitter sensitivity.

13. 13
RESULTS
 PR is quite less in the outdoor environment due to high interference.
 Deterministic channel model ESP-MESH protocol, within the radius of 1m. Probability
of connection is 100%.

14. 14
APPLICATIONS POSSIBLE WITH ESP8266 MESH
INDOOR LIGHTING
AUTOMATION
INDOOR AIR QUALITY
MEASUREMENT
CONDITION MONITORING OF
DEVICES IN INDOOR
ENVIRONMENTS

15. THANKYOU!
15