Transcript Digi Zigbee Mesh networking

ZigBEE
Fundamentals of ZigBee
• Low Cost
• Low Power
• Security-enabled
• Reliable
• Initial Target Markets were AMR, Building
Automation, and Industrial Automation (M2M
Comms)
ZigBee Protocol
• Where Does ZigBee Fit?
– Data Rate vs. Range vs. Battery Life (not shown)
Faster
Wireless
Video
Applications
UWB
Peak Data Rate
802.11g
Wireless Data
Applications
802.11a
IrDA
Wi-Fi®
802.11b
Cellular
2.5G/3G
Slower
Bluetooth™
Data
Transfer
ZigBee™
Wireless
Networking
Closer
Range
Farther
Wireless Standards Comparison
Feature(s)
IEEE 802.11b
Bluetooth
ZigBee
Battery Life
Complexity
Nodes/Master
Hours
Very Complex
32
Enumeration
up to 3 seconds
Days
Complex
7
Enumeration
up to 10 seconds
Range
100m-1000m
10m
Extendability
RF Data Rate
Roaming possible
11Mbps
Authentication Service Set
ID (SSID)
No
1Mbps
Years
Simple
64000
Enumeration
up to 30 milliseconds
70m-300m (ETSI), 1600m
(FCC)
Yes
250Kbps
128-bit AES and Application
Layer user defined
Latency
Security
64-bit, 128-bit
The Value of Mesh:
Extending Range
•out of range, no RF connectivity
•Point-to-Multipoint
•Reduced Function Device
•Communications Flow
The Value of Mesh:
Extending Range
•leverage network nodes to increase range
and establish RF connectivity
•RF Node
•Communications Flow
•Mesh Node Hopping
The Value of Mesh:
Self Healing/Discovery
•unexpected interruptions in the network can
be automatically compensated for by redirecting communication
•RF Node
•Communications Flow
•Mesh Node Hopping
Section 1
ZIGBEE PRO FEATURE SET
ZigBee Feature Sets
• ZigBee releases are defined as “Feature
Sets”
– A Feature Set refers to a group, or set, of features.
There are two Feature Sets in the latest update to
the ZigBee specification: ZigBee Feature Set and
the ZigBee PRO Feature Set.
• “ZigBee 2004”, “ZigBee 2006”, and “ZigBee
2007” are colloquial references and not
endorsed by the ZigBee Alliance
•IEEE
•Need for 802.15.4
WPANs released
•Point-tomultipoint / peerto-peer networks
•ZigBee
“2004”
ratified
•ZigBee
“2004”
available
•ZigBee
Feature
Set
available
•“Enhanced”
•Feeble,
mesh; pseudo•mesh
stochastic
networking; treeaddressing;
based addressing
support for
architecture; very
more dense
small node
networks;
density
compatibility
issues
•ZigBee
PRO
Feature
Set
available
•“Smart
Energy”
profile
ratified
•Significantly
improved mesh;
support for
thousands of
nodes; broad
interoperability
ZigBee Feature Set (2004)
•Coordinator
•Router
•Reduced Function Device
•Communications Flow
•Tree Mesh
ZigBee Pro Feature Set
•Coordinator
•Router
•Reduced Function Device
•Communications Flow
•Stochastic Mesh
ZigBee & IEEE 802.15.4
• ZigBee uses the PHY and MAC defined
by 802.15.4
• Accordingly, ZigBee is a WPAN network,
but with added networking intelligence
• ZigBee inherits the RF characteristics of
its 802.15.4 platform:
– RF Link Budget
– Current Draw
Simplified ZigBee Stack
802.15.4 Protocol
•
802.15.4 Specifications
–
Supported Networks
•
•
–
Types of Nodes
•
•
–
ZigBee APS
ZigBee Network
802.15.4 MAC
802.15.4 PHY
Coordinator
End Node
Reliable Delivery
•
•
–
–
Point-Point
Point-Multipoint/Star
ZigBee AF
CSMA/CA
MAC-level (pt-pt) Retries/Acknowledgments
64-bit IEEE and 16-bit short Addressing
16 DSSS RF Channels
ZigBee
ZDO
802.15.4 Protocol
•
802.15.4 Nodes in a PAN (Personal Area
Network)
ZigBee Protocol
• Supported Networks
– Point-Point
– Point-Multipoint/Star
– MESH
• Types of Nodes
ZigBee AF
ZigBee APS
ZigBee Network
ZigBee
ZDO
802.15.4 MAC
802.15.4 PHY
– Coordinator
– End Node
– ROUTER
• Reliable Delivery
– CSMA/CA
– MAC-level (pt-pt) Retries/Acknowledgments
– MESH NETWORK-level (multi-hop) Retries/ACKs
• 16 DSSS RF Channels
ZigBee Protocol
•
ZigBee Nodes in a PAN (Personal Area
Network)
•Coordinator
•One per PAN
•Establishes/Organizes a PAN
•Mains-powered
•Router
•Optional
•Several can be in a PAN
•Mains-powered
•End Device
•Several can be in a PAN
•Low power
ZigBee Protocol
• ZigBee Specifications
– Addressing
• 64-bit IEEE Address
ZigBee AF
ZigBee APS
ZigBee Network
ZigBee
ZDO
802.15.4 MAC
802.15.4 PHY
– Unique to every 802.15.4 device in the world
– Permanent, assigned during mfg
• 16-bit Network Addressing
–
–
–
–
Unique to each module within a PAN
Used in Routing Tables
Used for data transmissions, etc.
Volatile Address - Can Change
ZigBee Protocol needs/uses
• 802.15.4 Data Transmission modes
– Broadcast Mode
• To send a broadcast packet to all radios regardless
of 16-bit or 64-bit addressing
– Unicast Mode – Guaranteed Delivery
• 64-bit IEEE Addressing
– Destination 64-bit Address to match 64-bit source
address of intended receiver.
• 16-bit Network Addressing
– Destination 16-bit Address to match 16-bit source
address of intended receiver
ZigBee Protocol
PAN Network Formation
– Coordinator must select an unused operating
channel and PAN ID
• Energy scan on all channels
• Sends Beacon request (Broadcast PAN ID)
• Listens to all responses and logs the results
– After the Coordinator has started, it will allow
nodes to join to it for a time based on the
specified Node Join Time
C
ZigBee Protocol
• Router Startup
– A new Router must locate a Router that has
already joined a PAN or a Coordinator
• Sends a Broadcast PAN ID on each channel
• Returns sent via Unicast
– Router will then try to join to a Router or
Coordinator that is allowing joining
ZigBee Protocol
• End node: Low-power Sleep Modes
• End Node Startup
– A new End node must locate a Router that has
already joined a PAN or a Coordinator
• Sends a Broadcast PAN ID on each channel
• Returns sent via Unicast
– End node will then try to join to a parent (Router
or Coordinator) that is allowing joining
Single Point of Failure
Common Belief:
If a Coordinator fails, the network fails
FALSE:
If a Coordinator fails, the network
continues to function, but without
certain non-essential features of the
Coordinator
ZigBee Protocol
• Broadcast Transmissions - Relayed to All Nodes
– No Acks are transmitted – Routers listen to neighboring Routers to
know if message was retransmitted
– Retransmit if neighbors are not heard (up to 2 times)
– Broadcast Transaction Table used to ensure Routers do not repeat
a message they have already repeated
– Expensive time wise
R
R
R
R
R
C
R
R
R
R
ZigBee Protocol
• Route Discovery consists of the following commands:
– Route Request (broadcast)
• 64-bit address used to find the local 16-bit address (Network
address discovery)
• Routing tables based on 16-bit address
– Route Reply (unicast)
• Positive acknowledgement returned
• If node is gone- Network address discovery fails
R2
R7
C
R1
R3
R6
R5
R10
ZigBee Protocol
• Normal Data Transmissions
(Unicast - established Network)
• R1 must transmit data to R10.
• MAC ACKs are transmitted for each hop.
• One Network ACK is transmitted from the Destination
node back to the Source
R1
R7
R8
R2
R4
R3
C
R5
R9
R6
R10
ZigBee Protocol
Disabled Node
R1
X
R7
R2
R4
R3
C
R5
R8
R9
R6
R10
ZigBee Protocol
Disabled Node
• New Route Discovery Request (broadcast)
64-bit address used to find the local 16-bit address
(Network address discovery)
R1
X
R7
R2
R4
R3
C
R5
R8
R9
R6
R10
ZigBee Protocol
Disabled Node
• New Route sent back along best path (unicast)
• Coordinator not necessary after network setup
R1
X
R7
R2
R4
R3
C
R5
R8
R9
R6
R10
ZigBee Protocol
• Sleeping end node (child)
– Associates with a parent
• Parent takes over Zigbee network communications
while child is sleeping
• Parent must always be awake (router or coordinator)
• Number of childs per parent is limited
R1
R7
R8
R2
R4
R3
C
R5
R9
R6
E10
Section 2
DIGIMESH
The Value of Mesh
•many common mesh technologies require
different node types with a parent/child
relationship to achieve mesh node hopping
•Coordinator
•Router
•Reduced Function Device
•Communications Flow
•Mesh Node Hopping
DigiMesh Topology
•DigiMesh Router
•Communications Flow
•Peer-to-Peer Mesh
DigiMesh Network Overview
• Simple relative to Parent/Child-based mesh
technologies
• Support for Sleeping Routers
• Unpredictable timing (like all mesh networks)
• Poor latency performance relative to
multipoint technologies (like all mesh
networks)
• Lower sustained throughput relative to
multipoint products (like all mesh networks)
How DigiMesh is Different
Parent/Child Mesh
DigiMesh
• Parent/Child Hierarchy
• Peer-to-Peer Hierarchy
• Multiple Node Types
• One Node Type
• No Sleeping Routers
• Support for Sleeping Routers
• Complex Setup
• Simple Setup
• Most Commonly 2.4 GHz
• 900 MHz and 2.4 GHz
• Open Protocols Available
• Proprietary Protocol