Bluetooth mesh is a new Bluetooth technology which allows secure networks of thousands of devices to be formed and one of the primary applications that Bluetooth mesh was created for is the truly smart, connected building. It was designed from the outset with reliability, security and scalability as key goals and with the ability to meet the sophisticated and technically challenging engineering requirements of the smart building and smart industry. This session will explore the concepts, technicalities and uses of Bluetooth mesh networking.

1. An Introduction to Bluetooth Mesh
Martin Woolley, Bluetooth SIG @bluetooth_mdw
Amsterdam | April 2-3, 2019

2. point-to-point 1:1
BR/EDR
broadcast 1:m
Low Energy (LE)
many to many m:m
Mesh
Bluetooth now comes in three delicious flavours

3. relationship between Bluetooth technologies
Bluetooth BR/EDR
Bluetooth mesh networking
Bluetooth Low EnergyRADIO
NETWORKING

4. Bluetooth Mesh
Networks

5. multi-hop, multi-path, multicast

6. Bluetooth Mesh
Node Network Roles

7. relay nodes
R
RR
R = Relay function on
Relays retransmit messages so that they
can travel further, in a number of “hops”
Some nodes can act as “relays” however
Messages get sent to other nodes that are
in direct radio range of the publishing node

8. friend nodes and low power nodes
Low Power Node
(sensor)
Friend
Low power nodes (LPNs) are highly power
constrained
To avoid the need to operate at a high(er)
duty cycle to receive messages from the
mesh, an LPN works with a Friend
Friend nodes store messages addressed to
LPNs they are friends with and forward
them when the LPN occasionally polls

9. friend nodes and low power nodes
Low Power Node
(sensor)
Friend
To: Sensor
“set temperature thresholds”
Low power nodes (LPNs) are highly power
constrained
To avoid the need to operate at a high(er)
duty cycle to receive messages from the
mesh, an LPN works with a Friend
Friend nodes store messages addressed to
LPNs they are friends with and forward
them when the LPN occasionally polls

10. friend nodes and low power nodes
STORED
MESSAGE(S)
Low Power Node
(sensor)
Friend
To: Sensor
“set temperature thresholds”
Low power nodes (LPNs) are highly power
constrained
To avoid the need to operate at a high(er)
duty cycle to receive messages from the
mesh, an LPN works with a Friend
Friend nodes store messages addressed to
LPNs they are friends with and forward
them when the LPN occasionally polls

11. friend nodes and low power nodes
STORED
MESSAGE(S)
“do you have any
messages for me?”
Low Power Node
(sensor)
Friend
To: Sensor
“set temperature thresholds”
Low power nodes (LPNs) are highly power
constrained
To avoid the need to operate at a high(er)
duty cycle to receive messages from the
mesh, an LPN works with a Friend
Friend nodes store messages addressed to
LPNs they are friends with and forward
them when the LPN occasionally polls

12. friend nodes and low power nodes
STORED
MESSAGE(S)
“do you have any
messages for me?”
Low Power Node
(sensor)
Friend
To: Sensor
“set temperature thresholds”
To: Sensor
“set temperature thresholds”
Low power nodes (LPNs) are highly power
constrained
To avoid the need to operate at a high(er)
duty cycle to receive messages from the
mesh, an LPN works with a Friend
Friend nodes store messages addressed to
LPNs they are friends with and forward
them when the LPN occasionally polls

13. proxy nodes
P
Bluetooth low energy devices like
smartphones can communicate with a mesh
network via a proxy node
LE GATT
MESH

14. proxy nodes
Proxy
Bluetooth low energy devices like
smartphones can communicate with a mesh
network via a proxy node
mesh monitoring and control applications
LE GAP and GATT
MESH

15. Bluetooth Mesh
Communication and
Interaction

16. messages and state
State: OnOff = Off
State: OnOff = Off State: OnOff = Off
nodes communicate with each other by
sending messages
access messages operate on state values
SET - change of state
GET - retrieve state value
STATUS - notify current state
ACK vs UNACK
nodes have state values which reflect
their condition (e.g. ON or OFF)

17. messages and state
State: OnOff = Off
State: OnOff = Off State: OnOff = OffState: OnOff = On
State: OnOff = On
State: OnOff = On
nodes communicate with each other by
sending messages
access messages operate on state values
SET - change of state
GET - retrieve state value
STATUS - notify current state
ACK vs UNACK
nodes have state values which reflect
their condition (e.g. ON or OFF)

18. the publish/subscribe communication model
Kitchen Dining Room Hallway Bedroom Garden
Subscribe
Publish

19. Bluetooth Mesh
Node Composition

20. node composition
a node consists of an arrangement of
elements
models
states
each element has its own address
NODE
ELEMENT ELEMENT
MODEL
STATE
STATE
STATE
MODEL
STATE
MODEL
STATE
STATE
MODEL
STATE
note: a model is sometimes owned by multiple elements

21. models
ServerGeneric OnOff
Server
Generic OnOff
Client
define node functionality
define states, messages, state transitions
and behaviors
client, server and control types
generics such as onoff client and server
lighting, sensors, scenes & time

22. node composition
single node
3 elements
multiple models and states
0x0100 0x0101 0x0102
node
elements
models
states
generic onoff server
light lightness server
light lightness actual
light lightness last
light lightness range
generic onoff

23. Bluetooth Mesh
Security

24. devices and network membership
only members of the same network can
talk to each other
Bluetooth mesh networks are secure
a security process called provisioning
makes a device a member of a network

25. devices and network membership
Provisioner: converting
a device to a node
Device is now a
node on the network
only members of the same network can
talk to each other
Bluetooth mesh networks are secure
a security process called provisioning
makes a device a member of a network

26. Bluetooth mesh: Security
• Mandatory, cannot be reduced
• Encryption and authentication
• Separate security for network and each application
• Area isolation
• Message obfuscation
• Protection from replay and trashcan attacks
• Secure device provisioning

27. network key (netkey)
origin: provisioning
use: derivation of other keys
encryption key
origin: derived from netkey
using the k2 function
use: secures data
at the network
layer
privacy key
origin: derived from
netkey
using the k2 function
use: obfuscation
of network header
information
ref: mesh profile 1.0 section 2.3.9.1
application key
(appkey)
origin: created by
the config. client
and provided to nodes
after provisioning
use: secures
application data
at the upper transport
layer
Bound to one or more
models.
device key (devkey)
origin: established
during provisioning
use: secures communication
between the config. client
and individual node
appkey is bound to a netkey
devkey is bound to all
netkeys known to a node

28. Bluetooth mesh
Anatomy of a smart lighting system

30. Switch Models Light Models Sensor Models

31. Switch Models Light Models Sensor Models
Generic On/Off Server

32. Switch Models Light Models Sensor Models
Generic On/Off Client Generic On/Off Server

33. Switch Models Light Models Sensor Models
Light Lightness Server
Light HSL Server
Generic On/Off Client Generic On/Off Server

34. Switch Models Light Models Sensor Models
Light Lightness Server
Light HSL Server
Generic On/Off Client Generic On/Off Server
Light LC Server
Sensor Server

35. Switch Models Light Models Sensor Models
Light Lightness Server
Light HSL Server
Generic On/Off Client Generic On/Off Server
Light LC Server
Sensor Server
State Binding

36. Bluetooth mesh
Scalability

37. scalability
max 32,767 nodes per network
The fastest low power radio
small, highly optimised packets
hundreds of multicast messages per
second
multicast: 1 message can control many devices
point to point range hundreds of metres

38. scalability and the fundamentals of RF
radio is a shared medium
collisions are what limits scalability

39. scalability and the fundamentals of RF
an anonymous technology
(not Bluetooth)
e.g. 250 kb/s

40. scalability and the fundamentals of RF
Bluetooth mesh
using Bluetooth Low Energy
1000 kb/s
less air time per packet
so more capacity for work

41. scalability and the fundamentals of RF
Bluetooth mesh
much smaller packets
less airtime
fewer collisions
more “work”
29 octets payload

42. scalability and the fundamentals of RF
Bluetooth mesh
using Bluetooth Low Energy
3 x radio channels
3 x more capacity
used for enhanced reliability

43. Bluetooth Mesh
Demonstration

44. Bluetooth Mesh
What next?

45. Bluetooth SIG Resources - Reading Material

46. Bluetooth SIG Resources - hands-on education
Bluetooth Mesh Developer Study
Guide
Mesh Proxy Kit

47. Unthinkably ConnectedUnthinkably Connected
3 April 2019 40/ Bluetooth SIG Proprietary
Twitter: @bluetooth_mdw
questions?
kevin.ke@oneplus.net.