wireless iot: the last 100 metres
TRANSCRIPT
London IoT Meetup, 24-Nov-2015
Wireless IoT: The last 100 metres
Peter Claydon
Agenda
• A slide about ContinuumBridge
• Ways of connecting by wireless
• Factors influencing which protocol to choose
• Pros and cons of different protocols
• Conclusion
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ContiuumBridge – What we do
RetailSmart
EnergyWarranty/
MaintenanceE-HealthSecurity
Assisted
Living
Services
User Interface BridgeDashboards
Facilities
Connect devices to the Internet
Manage them
Provide connected services
3
Connecting by wireless
4
0 10-100 2,000 5,000 metres
Hub
Base
Station
Network
Servers
Which protocol? The laws of physics
• FSPL = Free Space Path Loss
• What this means is that, all else being equal a radio signal will go
approx. 3x the distance at 870 MHz (eg: Z-Wave) as at 2.4 GHz (eg:
WiFi)
• Also, low frequencies:
– Have better building penetration
– Reflect/refract better
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Which protocol? Meshing
• Messages can be routed through other devices
• Routing nodes generally must be mains powered
• Need to think about where routing nodes are needed
– Difficult for many applications
• Meshing protocols:
( ) ( )
HubRouting
NodeLeaf
Node
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Which protocol? Throughput
Protocol Throughput Frequency Band (MHz) *
Bluetooth LE 0.27 Mbps 2400
WiFi 10+ Mbps 2400
IEEE 802.15.4ZigBee, 6LoWPAN, Thread
0.25 (0.02) Mbps 2400, (868) **
Z-Wave 0.04 Mbps 868
SigFox 16 bps/0.02 bps over time 868
LoRa 10 Kbps instantaneous 868
3GPPGPRS, EDGE, HSPA, LTE
48 Kbps -> 100 Mbps+ 800, 900, 1800, 2100
• Unless you need audio or video, a few bits per second is enough
• Also need to consider latency (how long data takes to get there)
* European bands. Other parts of world use some different bands
** 802.15.4-based protocols are almost always in 2.4 GHz ISM band
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Which protocol? Battery life
• There’s no magic – save power by turning things off
• In other words:
– Don’t communicate more often than you need to
– Keep other processing to a minimum
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Protocols – Bluetooth Low Energy
Pros Cons
Connects to all smart phones Can your application reply on a phone?
Cheap radio Can only assume 10 metres range
Very large community No meshing today (it’s coming)
Coin cells only last months
9
Protocols – WiFi
Pros Cons
Connects to all smart phones Connections need to be managed by people
Connects to ubiquitous routers
Large community Today’s WiFi is power-hungry(802.11ah is coming)
Cheap radio
Better range than Bluetooth
Higher throughput than other protocols
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Protocols – IEEE 802.15.4
Pros Cons
Lower power consumption than WiFi Typically short range without meshing
6LoWPAN & Thread use IPv6 – can be routed directly to cloud platforms
There are lots of flavours to choose from
Support mesh Lack off-the-shelf devices
Becoming more widely used – support from Google & others
Less immunity to interference than WiFior Bluetooth
11
Protocols – Z-Wave
Pros Cons
Lots of off-the-shelf devices available Typically short range without meshing (comparable to WiFi)
Battery life of 1-3 years, depending on device type & application
Proprietary (chips & protocol software), so modems cost a few £1
Supports mesh Standard hubs are restrictive (designed for home automation)
Widely supported
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Protocols – Low Power, Wide-Area Networks
Pros Cons
Range of up to 5 km Limited data throughput, in some cases very limited (12 bytes, 6x per hour)
Long battery life All proprietary. Which one do you use? *
Managed networks Managed networks
Cheap radios
No need for a local hub
• * There are more than are listed here
• 3GPP is standardising its own LP-WAN
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Protocols – Mobile networks
Pros Cons
Existing networks with good coverage Coverage is anything but universal
Networks in almost every country Relatively expensive radios (but GPRS < £8in small quantities)
No need for a hub (can be used to connect to a hub)
At least £1 per month connection charge
Built-in security Short battery life (unless modem connectsvery infrequently)
Large community
IP connection directly to cloud platforms
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Conclusion
Choice depends on the application
– There are a lot of choose from and probably always will be
What did ContinuumBridge do?
1. Started using Bluetooth and Z-Wave
– Battery life and range are not good enough for some applications
2. Proprietary 868 MHz protocol to cellular-connected hub
– Range: 3 floors of an office building
– Battery life: 4-5 years
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