Digi Zigbee Mesh networking

1
ZigBEE
2
Fundamentals of ZigBee

• Low Cost
• Low Power
• Security-enabled
• Reliable
• Initial Target Markets were AMR, Building
  Automation, and Industrial Automation (M2M Comms)

3
ZigBee Protocol

• Where Does ZigBee Fit?
• Data Rate vs. Range vs. Battery Life (not shown)

4
Wireless Standards Comparison
5
The Value of MeshExtending Range

• out of range, no RF connectivity

• Point-to-Multipoint

• Reduced Function Device

• Communications Flow

6
The Value of MeshExtending Range

• leverage network nodes to increase range and
  establish RF connectivity

• Mesh Node Hopping

• RF Node

• Communications Flow

7
The Value of MeshSelf Healing/Discovery

• unexpected interruptions in the network can be
  automatically compensated for by re-directing
  communication

• Mesh Node Hopping

• RF Node

• Communications Flow

8
Zigbee Pro Feature Set

• Section 1

9
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

10

• ZigBee Events

• ZigBee Technology

• ZigBee PRO Feature Set available

• Smart Energy profile ratified

• ZigBee Feature Set available

• IEEE 802.15.4 released

• ZigBee 2004 ratified

• ZigBee 2004 available

• Need for WPANs

• 2004

• 2005

• 2006

• 2007

• 2008

• 2003

• Enhanced mesh pseudo-stochastic addressing
  support for more dense networks compatibility
  issues

• Point-to-multipoint / peer-to-peer networks

• Feeble,
• mesh networking tree-based addressing
  architecture very small node density

• Significantly improved mesh support for
  thousands of nodes broad interoperability

11
ZigBee Feature Set (2004)

• Coordinator

• Router

• Tree Mesh

• Reduced Function Device

• Communications Flow

12
ZigBee Pro Feature Set

• Coordinator

• Router

• Stochastic Mesh

• Reduced Function Device

• Communications Flow

13
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

14
Simplified ZigBee Stack

• User defined

• ZigBee Device Object (ZDO)

• User Application

• ZigBee APS

• Security Services

• ZigBee Protocol

• ZigBee Network Layer

• MAC

• IEEE 802.15.4

• PHY
• (2.4 GHz, 900 MHz, 868 MHz)

15
802.15.4 Protocol

• 802.15.4 Specifications
• Supported Networks
• Point-Point
• Point-Multipoint/Star
• Types of Nodes
• Coordinator
• End Node
• Reliable Delivery
• CSMA/CA
• MAC-level (pt-pt) Retries/Acknowledgments
• 64-bit IEEE and 16-bit short Addressing
• 16 DSSS RF Channels

ZigBee AF
ZigBee ZDO
ZigBee APS
ZigBee Network
802.15.4 MAC
802.15.4 PHY
16
802.15.4 Protocol

• 802.15.4 Nodes in a PAN (Personal Area Network)

17
ZigBee Protocol

• Supported Networks
• Point-Point
• Point-Multipoint/Star
• MESH
• Types of Nodes
• 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 AF
ZigBee ZDO
ZigBee APS
ZigBee Network
802.15.4 MAC
802.15.4 PHY
18
ZigBee Protocol

• ZigBee Nodes in a PAN (Personal Area Network)

19
ZigBee Protocol

• ZigBee Specifications
• Addressing
• 64-bit IEEE Address
• 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 AF
ZigBee ZDO
ZigBee APS
ZigBee Network
802.15.4 MAC
802.15.4 PHY
20
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

21
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

22
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

23
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

24
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

25
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
26
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

R7
R2
C
R6
R1
R10
R3
R5
27
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
R9
C
R6
R4
R3
R10
R5
28
ZigBee Protocol
Disabled Node
R1
X
R7
R8
R2
R9
C
R6
R4
R3
R10
R5
29
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
R8
R2
R9
C
R6
R4
R3
R10
R5
30
ZigBee Protocol

• Disabled Node
• New Route sent back along best path (unicast)
• Coordinator not necessary after network setup

R1
X
R7
R8
R2
R9
C
R6
R4
R3
R10
R5
31
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
R9
C
R6
R4
R3
E10
R5
32
Digimesh

• Section 2

33
The Value of Mesh

• many common mesh technologies require different
  node types with a parent/child relationship to
  achieve mesh node hopping

• Coordinator

• Router

• Mesh Node Hopping

• Reduced Function Device

• Communications Flow

34
DigiMesh Topology

• Peer-to-Peer Mesh

• DigiMesh Router

• Communications Flow

35
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)

36
How DigiMesh is Different

• Parent/Child Mesh

• DigiMesh

• Parent/Child Hierarchy
• Multiple Node Types
• No Sleeping Routers
• Complex Setup
• Most Commonly 2.4 GHz
• Open Protocols Available

• Peer-to-Peer Hierarchy
• One Node Type
• Support for Sleeping Routers
• Simple Setup
• 900 MHz and 2.4 GHz
• Proprietary Protocol