zigbee technology

Semiconductors 1
A SEMINAR REPORT ON
THE ZIGBEE TECHNOLOGY
BY
karthik nch

Semiconductors 2
Why ZigBee?
• Standard in a fragmented market
– Many proprietary solutions, interoperability issues
• Low Power consumption
– Users expect battery to last months to years!
• Low Cost
• High density of nodes per network
• Simple protocol, global implementation

Semiconductors 3
Low Data Rate
Radio Devices
• TV
• VCR
• DVD
• CD
• Remote
• Mouse
• Keyboard
• Joystick
• Gamepad
• Security
• HVAC
• Lighting
• Closures
• PETs
• Gameboys
• Educational
• Monitors
• Diagnostics
• Sensors
Industrial &
Commercial
Consumer
Electronics
Personal
Healthcare
• Monitors
• Sensors
• Automation
• Control
Toys
&
Games
Home
Automation
PC
Peripherals
ZigBee -Target Markets

Semiconductors 4
ZigBee - General Characteristics
• Data rates of 250 kbps and 20 kbps
• Star topology, peer to peer possible
• 255 devices per network
• CSMA-CA channel access
• Optional Guaranteed Time Slot
• Fully handshaked protocol for transfer reliability
• Low power (battery life multi-month to years)
• Dual PHY (2.4GHz and 868/915 MHz)
• Range: 10m nominal (1-100m based on settings)
• Location Aware:Yes, but optional

Semiconductors 5
FREQUENCY BANDS AND DATA RATES

Semiconductors 6
Silicon
PHY Layer
MAC Layer
Network Layer
ZigBee
Stack
Application
Application Support (sub layer)
Application Layer
Customer
ZigBeeAlliance
IEEE
ZigBee Alliance - IEEE - Customer
Relationship

Semiconductors 7
Virtual links
Network Topology
Network coordinator(FFD)
Network node (FFD)
Communications flow
IEEE node
(RFD)

Semiconductors 8
Full function device
Reduced function device
Communications flow
Master/slave
PAN
Coordinator
IEEE 802.15.4 MAC Overview
Star Topology

Semiconductors 9
Full function device Communications flow
Point to point Cluster tree
IEEE 802.15.4 MAC Overview
Peer-Peer Topology

Semiconductors 10
NETWORK MODEL

Semiconductors 11
The Network Coordinator
• Transmits network beacons
• Sets up a network
• Manages network nodes
• Stores network node information
• Routes messages between paired nodes
• Receives constantly

Semiconductors 12
The Network Node
• Is generally battery powered
• Searches for available networks
• Transfers data from its application as necessary
• Determines whether data is pending
• Requests data from the network coordinator
• Can sleep for extended periods

Semiconductors 13
Supported Traffic Types
• Periodic data
– Application defined rate(e.g: sensors)
• Intermittent
– Basic communication(e.g: Light switch)
• Repetitive low latency data
– Allocation of guaranteed time slots
(e.g: mouse)

Semiconductors 14
FRAME STRUCTURE
4 to 20 bytes are used for address information, which can include both source and
destination information. This leaves a maximum of 104 bytes of actual data.

Semiconductors 15
SUPER FRAME STRUCTURE
DIVIDED INTO 16
EQUAL SIZED SLOTS
WITH BECON
REQUESTS
MAY ALLOCATE
UPTO 7 SLOTS
FOR GTS
(Guaranteed time
slots)
APPLICATION
Super frame structure allows GTS operation, its is initiated by
coordinator

Semiconductors 16
NETWORK COMMUNICATIONS

Semiconductors 17
THE ZIGBEE ALLIANCE
CompXs

Semiconductors 18
ZigBee vs Bluetooth
Competition or Complementary?

Semiconductors 19
Bluetooth is Best
For :
• Ad-hoc networks between
capable devices
• Handsfree audio
• Screen graphics, pictures…
• File transfer
But ZigBee is
Better
IF :
• The Network is static
• Lots of devices
• Infrequently used
• Small Data Packets

Semiconductors 20
Air Interface:
ZigBee
DSSS
11 chips/ symbol
62.5 K symbols/s
4 Bits/ symbol
Peak Information Rate
~128 Kbit/second
Bluetooth
FHSS
1 M Symbol / second
Peak Information Rate
~720 Kbit/second

Semiconductors 21
Silicon
RF
Baseband
Link Controller
Voice
Link Manager
Host Control Interface
L2CAP
Telephony
Control
Protocol
Intercom
Headset
Cordless
GroupCall
RFCOMM
(Serial Port)
OBEX
HOST
MODULE
Bluetooth
Stack
Applications
vCard
vCal
vNote
vMessage
Dial-up
Networking
Fax Service
Discovery
Protocol
User Interface
Bluetooth Protocol Stack Size/Complexity

Semiconductors 22
Bluetooth:
• New slave enumeration = >3s
• Sleeping slave changing to active = 3s typically
• Active slave channel access time = 2ms typically
ZigBee:
• New slave enumeration = 30ms typically
• Sleeping slave changing to active = 15ms typically
• Active slave channel access time = 15ms typically
Timing Considerations
ZigBee protocol is optimized for timing critical applications

Semiconductors 23
Power Considerations
ZigBee
• 2+ years from ‘normal’
batteries
• Designed to optimize slave
power requirements
Bluetooth
• Power model as a mobile
phone (regular charging)
• Designed to maximize ad-
hoc functionality
Application example of a light
switch with respect to latency and
power consumption …...

Semiconductors 25
ZigBee - Bluetooth - PLC Comparison
ZigBee Bluetooth PLC
Cost (BOM) $5 $10 $15-$40
Power years hours N/A
Data Rate 250Kbps 720Kbps 3/10 Mbps
Complexity Low Medium High
Density 255 + 7 20-250
Interop Yes Yes No
Ease of Use Simple Moderate Restrictive
Latency 15ms >3s <15ms
Interference Low High High
Security High High Low

Semiconductors 26
Conclusion
• ZigBee and Bluetooth are two solutions for two application
areas

zigbee technology

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