Harrison Chin, P.Eng Senior Field Applications Engineer · App level retries SAR and/or model calls...
Transcript of Harrison Chin, P.Eng Senior Field Applications Engineer · App level retries SAR and/or model calls...
GO BIG, GO FAST, GO HOMEWhen Mesh Network Design MattersHarrison Chin, P.EngSenior Field Applications Engineer
OVERVIEW
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Introduction Test Methodology Reasoning
Relevant Use Cases Test Results Conclusion
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WHAT IS A MESH NETWORK?A system of interconnected nodes which cooperatively transport data from one node to another.
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WHY USE A MESH NETWORK?
Maximize Area Coverage
Nodes extend the effective range
Maximize Reliability
Redundant travel paths for data
Minimize Security Risks
Operate as independent networks
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USER INTERACTIVE SYSTEMSLatency sensitiveUse cases• Home automation• Lighting control• Door bells• Digital assistants
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USE CASELIGHTING CONTROL• Users expect instantaneous
response• Within 100ms or less
• Users expect consistency• Groups of lights change
together
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LIGHTING CONTROL SPECIFICATIONS• Bytes of data per packet• State data• On/Off• Intensity
• Infrequent events• Minutes between
changes• Strict latency bounds
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OBSERVATIONAL SYSTEMSThroughput sensitiveUse cases• Process management• Office space
management• Asset tracking• Vertical farm
monitoring©
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USE CASEASSET TRACKING• Hundreds of physical assets• Data is required in a regular and
reliable basis• Location, temperature, motion• Timescale in seconds to minutes
• Operate under a variety of environmental conditions
• Straightforward to deploy in scale
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ASSET TRACKING SPECIFICATIONS• Dozens of bytes per packet• Location• Sensor data
• Periodic events• Seconds between asset updates
• Large volume of concurrent traffic• All node data is important
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Use Case Latency Throughput Reliability
Lighting Control ✓ ✓
Asset Tracking ✓ ✓
KEY PERFORMANCE INDICATORS
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• Average Round Trip Time - Latency• Request a response from a node and measure how long it took
• Aggregate Gateway Throughput - Throughput• !"#$%& '( $)*%+ &%,%-.%/ (&'# 011 !'/%+
*'*01 *-#% ('& 011 +",,%++("1 &%+2'!+%+
• Average Success Rate - Reliability• !"#$%& '( &%+2'!+%+ &%,%-.%/*'*01 !"#$%& '( &%3"%+*+
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HOW DO WE MEASURE PERFORMANCE?
PING TESTING• Gateway-based Architecture• Phone/switch is the gateway for lighting• Cellular/Satellite/Hardline bridge for Asset tracking ©
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PING TESTING
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TEST FRAMEWORK
Bluetooth Mesh ANT BLAZE
nRF52832-based modules nRF52832-based modules
Certified nRF BLE Mesh 3.1.0 ANT BLAZE Libraries
Test software provided by Nordic Semiconductor Test software provided by Garmin
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TRAFFIC PATTERNSSingle Ping• One node responds• Lights…visible feedbackGroup Ping• 10 nodes respond• Many sensors relaying data to gateway
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LAYOUT - DENSE - 30 NODES
RelayNodeGateway
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DENSE – 30 NODESTest Setup• ~4m spacing between nodes• ~8m spacing between relays• 4 relays in 30 nodes
• Kitchen Environment• Reduced BLE ADV Traffic
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132.53
25.57
5.49 8.6619.97
33.33
138.66
192.39
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5-Byte Single Ping 25-Byte Single Ping 5-Byte Group Ping 25-Byte Group Ping
Throughput (B/s)
Aggregate Throughput at Gateway (B/s)
Bluetooth Mesh ANT BLAZE
DENSE – 30 NODES
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5-Byte Single Ping 25-Byte Single Ping 5 Byte Group Ping 25-Byte Group Ping
Round Trip Time (ms)
Average Round Trip Time (ms)
Bluetooth Mesh ANT BLAZE
DENSE – 30 NODES
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Success Rate (%)
Average Ping Success Rate (%)
Bluetooth Mesh ANT BLAZE
DENSE – 30 NODES
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LAYOUT – SPARSE – 30 NODES
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SPARSE – 30 NODESTest Setup• ~10m Spacing• 30 Nodes Total• All Relays• 100 Test Cycles• Increased BLE ADV Traffic
Logan and Rainer*May not be a representative
depiction of all interns
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5-Byte Single Ping 25-Byte Single Ping 5-Byte Group Ping 25-Byte Group Ping
Throughput (B/s)
Aggregate Response Throughput at Gateway (B/s)
Bluetooth Mesh ANT BLAZE
SPARSE – 30 NODES
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Round Trip Time (ms)
Average Round Trip Time (ms)
Bluetooth Mesh ANT BLAZE
SPARSE – 30 NODES
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Success Rate (%)
Average Ping Success Rate (%)
Bluetooth Mesh ANT BLAZE
SPARSE – 30 NODES
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Latency
Throughput Reliability
You can only pick two.
TRADE-OFF TRIAD!= CONJOINED TRIANGLES OF SUCCESS
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WHY? SHARING A LIMITED RESOURCE… AIR TIME• Fundamental contention between…• Keeping nodes busy with required data transfers• “Throughput”
• Keeping nodes available to listen for new data requests• “Latency”
• Keeping nodes aware of failed data transfers• “Reliability”
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Parameter Bluetooth Mesh ANT BLAZE
RF channel N/A, ADV channels 78 channels, Up to 3
App level retries SAR and/or model calls Library calls in app
Proxy ADV Interval Modify for density N/A, As needed
Transmission interval Modify for concurrency N/A, Built-in
Transport layer repeats Modify for interference N/A, Built-in
Relay count Modify for coverage N/A, All relay
Time-to-live Modify for coverage N/A
Bearer layer repeats Modify for interference N/A
TUNING PARAMETERS FOR THE RIGHT BALANCE
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LIGHTING CONTROL RE-IMAGINED
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BLUETOOTH MESH TIME DOMAINLIGHTING CONTROL
Gateway
Node 1
Node 2
Node 3
Node …
Time
© 2018 Garmin Canada
Newly published data0-20ms before
broadcast
Minimal activity between new data events
Node N
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ASSET TRACKING RE-IMAGINED
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BLUETOOTH MESH TIME DOMAINASSET TRACKING
Node 2
Node 3
Node …
Node N
Time
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Gateway
Node 1
Concurrent message collisions
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BLAZE BROADCAST TIME DOMAIN BOTH USE CASES
Gateway
Node 1
Node 2
Node 3
Node …
Steady state of activity between new data events
Regular interval between transmissions
62.5-500ms
© 2018 Garmin Canada
Newly sent dataWaits for next period
Node N
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“CONTEXT IS FOR KINGS”• What are your requirements?• Latency• Throughput• Device count
• Where are the nodes being deployed?• Commercial• Residential• Industrial
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- Hint: “Starfleet” Captain
CONCLUSION
• Is ultra-low latency required?• Data suggests look into Bluetooth Mesh
• Is increased throughput more important?• Data suggests look into ANT BLAZE
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QUESTIONS?
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