ZigBee

1
ZigBee TinyOS

• TinyOS and ZigBee are not competitive
• TinyOS Operating System, Tool Chain, Component
  Library
• ZigBee Hybrid-Mesh Protocol on Top of 802.15.4
• Recently Ratified
• Home-Automation Oriented
• Powered Backbone I.e., Hybrid-Mesh
• Crossbow is active member of ZigBee Alliance
• Crossbow is developing ZigBee stack on-top of
  X-Mesh built in nesC/TinyOS

2
TinyOS and Zigbee

• TinyOS on MicaZ and Zigbee both use an 802.15.4
  physical layer
• RF signaling mechanisms are the same)
• The Zigbee Protocol Layer is being implemented in
  XMesh/TinyOS by Crossbow
• XMesh/TinyOS applications and Zigbee enabled
  TinyOS applications can coexist seamlessly
• Hundreds of TinyOS applications can tie into
  Zigbee networks and future Zigbee network devices
  can be tied into XMesh based networks

3
XMesh Zigbee Stack
App
App
ZigbeeDeviceControl

• Implementation of standard Zigbee abstractions in
  the TinyOS component framework.
• Command and event structure of TinyOS makes
  applications easily to develop and highly
  portable.

Application Support Layer
Network Support Layer
MAC Layer
802.15.4(CC2420)
4
TinyOS XMesh Stack
App

• TinyOS apps can be written to use XMesh, Queued
  Send or direct Active Messages
• Zigbee is just another TinyOS Service like XMesh

App
App
App
XMesh Multi-hop Network routing and discovery
Queued Send Buffer
Active Messages Delivery Layer (AM)
MAC Layer
802.15.4(CC2420)
5
TinyOS Routing Zigbee Compatibility

• Apps can use Zigbee, XMesh, AM or a combination
• Bridging apps on routing nodes can route across
  both types of network

App
App
App (bridge/combine)
App

ZigbeeDeviceControl
App
XMesh Multi-hop Network routing and discovery
Queued Send Buffer
Application Support Layer
Active Messages Delivery Layer (AM)
Network Support Layer
Auto-dispatch(FrameType)
Dual function MAC layer
802.15.4(CC2420)
6
Network Architecture
XMesh Com.
Zigbee Pan Com.
Hybrid Mote
Reliable XMesh routing links to Third-party
Zigbeedevices
Hybrid Mote
Hybrid Mote
PC
Hybrid Mote
Hybrid Mote
7
Overhead for dual-function devices

• CPU processing none
• TinyOSs event based processing only uses CPU
  resources when necessary, extra protocol
  implementations only used when necessary
• Flash Memory Size increase 8-12K
• RAM Memory Size increase of 40-80 bytes

8
Application Interface

• TinyOS component model easily moves apps from
  basic AM to XMesh to Zigbee
• Simple recompile
• Zigbee and Active Messages provides to
  applications through simple event-based interface
• Just as an app can easily be moved from AM to
  XMesh, it can be easily adapted to Zigbee by
  using the TinyOS component model

9
MICAz and IEEE802.15.4/ZigBee
10
Main Features of the IEEE 802.15.4 Standard

• Data rates of 250 kbits/s in 2.4 GHz RF band
• 16 channels, 2 MHz wide in the 2.4 GHz ISM band
• CSMA-CA channel access
• 128 Bit AES encryption in Hardware
• Low power consumption
• CC2420 Transmit 18 mA Receive 20 mA _at_1 mW
• All of PHY and part of MAC layers implemented in
  hardware
• For more information visit www.ieee802.org/15/

11
802.15.4 and 802.11b Spectrum Relationship

• Co-exists with WiFi, Bluetooth
• Channel selection is important

Note Channels 25, 26 are non-overlapping
5 MHz Spacing
802.15.4 Ch. 11 to Ch. 26
Ch. 15
Ch. 20
Ch. 20
Ch. 26
2405 MHz
2480 MHz
2 MHz
802.11 Ch. 1 to Ch. 11
25 MHz Spacing
Ch. 1
Ch. 6
Ch. 11
22 MHz
2412 MHz
2437 MHz
2425 MHz
2462 MHz
2475 MHz
2450 MHz
12
802.15.4 and 802.11b Channels
No overlaps with 802.11
13
WiFi 802.15.4/Zigbee Co-exitence Study

• Continuous data transfer on WiFi enabled Stargate
• Hi-power and low-power card
• XMesh (surge_reliable) mesh, 6 MICAz nodes
  measured
• Low-power card test

14
WiFi 802.15.4/Zigbee Co-existence Study (contd)

• Low-power Card Test