how zigbee/802.15.4 protocol simplifies wireless m2m ... · long battery life, selectable latency...

TMFreescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service namesare the property of their respective owners. © Freescale Semiconductor, Inc. 2006.

How ZigBee/802.15.4 Protocol SimplifiesWireless M2M CommunicationsJune 4th, 2008

Cyril ZaraderProduct Marketing Manager EMEA – Wireless Connectivity

TMFreescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names arethe property of their respective owners. © Freescale Semiconductor, Inc. 2007. 1

Topics

IEEE 802.15.4 : Made for Reliable Low PowerWireless Networking

ZigBee : Made for Simple Deployment of WirelessM2M Communications

ZigBee Compared to Other Industrial WirelessProtocols


Selection of Wireless Technologies

Range

Peak

Dat

a R

ate

Closer Farther

Slow

erFa

ster

UWBWireless DataApplications

WirelessVideo

Applications

IrDA

802.11g

802.11b

802.11a

2.5G/3G

Bluetooth™ZigBee™

DataTransfer

WirelessNetworking

Wi-Fi®

Cellular

NFC/RFID

802.15.4

802.15.1

802.15.3


Wireless Networking Technologies

N/ALonMark®

InteroperabiltyAssociation

Wi-FiTM

Alliance

UWBTM Forum& WiMediaTM

AllianceBluetooth® SIGZigBeeTM AllianceIndustry

Groups

P2P, Star,Mesh

Medium-dependentStarStarStarMesh, Star, TreeTopology

100-1,00032,00032128865,000Nodes

Alkaline(Months-Years)

N/ARechargeable(Hours)

Rechargeable(Hours-Days)

Rechargeable(Days-Weeks)

Alkaline(Months-Years)

BatteryOperation(Life)

Very Low-LowWiredHighLowLowVery LowPower

10-70 mMediumDependent10-100 m4-20 m10 m10-70 mRange

10-250 Kbps15 Kbps-10 Mbps11-105 Mbps110Mbps-

1.6Gbps723 Kbps250 KbpsData Rate

RFFrequency

Standard

868/915 MHz2.4 GHz

IEEE® 802.15.4

ZigBeeTM

433/868/900MHz

2.4 GHz

N/A (wiredtechnology)

2.4 GHz5.8 GHz

3.1-10.6 GHz(U.S.)2.4 GHz

ProprietaryEIA 709.1,2,3IEEE® 802.11a, b, g (n tobe ratified)

IEEE®

802.15.3a(to be ratified)

IEEE®

802.15.1

ProprietaryLonWorks®Wi-FiTMUWBTMBluetooth®

Key strengths Key weaknesses


IEEE 802.15.4 : Made forReliable Low PowerWireless Networking


Matching Applications to Wireless Technologies

Imagery and Audio• High-quality, live video and audio

� WUSB, Wi-Fi, WiMax

• Low to mid-quality, live or still images and low- to moderate-qualityaudio� WUSB, Wi-Fi, Bluetooth, 802.15.4, Cellular

Low- to moderate-rate communications and control systems• 802.15.4, Wi-Fi, Cellular

Extreme-battery-life sensor and control systems• 802.15.4• Months to years to decades, depending on the application and duty

cycle


Data Collection and Delivery Cost

Wireless cuts the data wire and saves the cost of installation androuting of specialized cables

� Running permanent wiring to a device can cost from €10 to €100 per meterin commercial facilities

� For homes, retrofitting control and monitoring cabling costs about €20 to €40per square meter of floor area covered

• Needs a source of permanent power or must be very battery-efficient

Removing the data wires AND removing the connection to permanentpower is the goal


Data Rate Matters

Typical Operating environments with dozens to hundreds ofmachines:

• Say what you need to say quickly, then get off the air� A busy channel is an unreliable channel� Keep the channel availability high to reduce retries, latency and improve

quality of service� Higher data rates make message transmission faster and channel

occupancy lower� Faster communications and longer sleep times can mean less energy

consumption

• BUT, transmitting faster than you need to can lead to� Increased transceiver cost� Tighter requirements on timing� Increased receiver complexity� Increased energy consumption


IEEE802.15.4 PHY Characteristics

Simple packet data protocolfor lightweight wirelessnetworks

• Released in May 2003• Primary channel access is via

Carrier Sense Multiple Access withcollision avoidance

• Message acknowledgement and anoptional beacon structure

• Multi-level security• Works well for

� Long battery life, selectable latencyfor controllers, sensors, remotemonitoring and portable electronics

• Configured for maximum batterylife, has the potential to last as longas the shelf life of most batteries

ZigBee relies upon IEEE 802.15.4,which has excellent performance in

low SNR environments


IEEE 802 Standards are Designed to Coexist

Frequency Domain• Multiple, non-aligned channels• Spread spectrum for added

robustness• Phase-Shift keying and direct-

sequence spread spectrum

Time Domain• Both 802.11 and 802.15.4 radios

“listen before talking” to avoidcollisions

Protocol Robustness• ACK required for successful data

transfer• No ACK, station tries again when

channel clears

802.11 packets

802.15.4 packets t

Retries


Low Channel Occupancy – Critical to Reliability

Typical scenario with 100 to 1000 devices

• Constant monitoring of the environment requires regularcommunications

• Even once every few minutes for all devices, this can mean hundreds ofmessages per minute

• 2.4GHz ZigBee data rates are 250kbps• Packets generally under 2ms in duration, and two-way

acknowledgement adds about 600us per message• In practical environments and usage, channel occupancy ~1%• Even with multiple nearby networks, the channel is mostly empty!• The channel is available when the network needs it


Mesh Networking Improves Robustness

ZigBee CoordinatorZigBee RouterZigBee End DeviceZigBee Device Associations


802.15.4 Summary

802.15.4 is designed to provide a solid foundation for sensing and control applications

Providing a global standard• 2.4 GHz provides global support for products• Additional sub 1 GHz work adding options for Asia, Europe, and US

Technology is real and available• Mass production since 2003• 7-10 Million units shipped in 2007

Provides a variety of sources for chipsets and network stacks• Eliminates the concerns with a single source• Provides lower cost and increased competition

Provides for key technology advantages for monitoring and control• Optimized for low duty cycle applications• Longer battery life (months to years)

Proving to be robust in the presence of interference• Channel Alignment – ideal for co-existence with other 2.4 GHz technologies• Clear Channel Assessment – improves collision avoidance• Short burst transmission


ZigBee : Made for SimpleDeployment of WirelessM2M Communications


ZigBeeZigBeeTMTM

Was created by the ZigBee Alliance

Is based on the IEEE 802.15.4 Standard

Targets wireless control and monitoring applications

Uses Mesh networking to cover large areas with short-range low-power radios

www.zigbee.org


IEEE 802.15.4 & ZigBee Alliance

PHY LAYER868MHz / 915MHz / 2.4GHz

MAC LAYER

SECURITY LAYER32- / 64- / 128-bit encryption

APPLICATION FRAMEWORK

APPLICATION/PROFILES

IEEE802.15.4

ZigBeeAlliancePlatform

ApplicationZigBee Platform StackSilicon

ZigBee or OEM

NETWORK LAYERStar / Mesh / Cluster-Tree


PAN coordinator (PANC)

Full Function Device (FFD,Router)

Reduced Function Device (RFD)

Star

Mesh

Cluster Tree

Network Topology Models


ZigBee Recap

ZigBee relies upon the robust IEEE 802.15.4 PHY/MAC to provide reliabledata transfer in noisy, interference-rich environments

• Message acknowledgement and an optional beacon structure• Multi-level security

Ideal For• Low data rate monitoring and control applications that require a robust network

� Low latency, infrequent, low data rate and small packet data• Large area coverage

� Using the mesh networks that support 1000 of devices• Ultra low power monitoring applications that operate for years on inexpensive

alkaline batteriesNot Ideal For

• Applications requiring long range without using routers• Mobile applications

� Being addressed in future revision• Streaming data


ZigBee Vs. Market Requirements

Cellular

Nodes Density

Ease of use

Radio Friendly

Nodes Density

Device Mobility

Network Scalability

Reliable Communications

Lightweight

ZigBeeUWBWiFiBluetoothMarket Requirements


Industrial WirelessProtocols Overview


WirelessHART™ Specification Technical Overview

Based on 802.15.4 – 2006• Specification completed in 2007

Focuses on features for reliabilityand co-existence

• Adds channel hopping� Uses TDMA with a fixed 10ms time slot� Black listing of bad channels� Provides for sleeping routers

• Higher default transmit power� +10dBm

• Mesh Network Topology� Based on DUST Networks TSMP (Time

Synchronized Mesh Protocol� Provides flexible network organization� Provides redundant paths� Self organizing and self healing

• Dynamic bandwidth allocation� Fixed bandwidth for prioritized data and

commands• Supports AES-128 ciphers and key support

Supports common HART devices• Wireless Field devices• Bridges, Gateways and Access Points

provide seamless access throughout thenetwork


ISA100.11a Technical Overview

Reliable low-power communication• Based on IEEE 802.15.4 radios in the 2.4

GHz ISM band• Time-synchronized channel-hopping to

sidestep RF interference and minimize powerconsumption

� Allows for FFD devices such as routers to sleepAdaptive Mesh Network

• Supports mesh, star-mesh and startopologies

• Self-organizing intelligence simplifiesinstallation and automatically adapts tochanging conditions

Robust Security• All messages protected with AES128 block

cipher• Secure communication and device

authentication enabled by exchange of secretkeys and unique device identifiers

Unified Application Interface• Provides an open and interoperable

application environment• Provides a common integration point for

multiple host systems


802.15.4 Protocol Stack Positioning

Cost

Less Sensitive

Cost S

ensitiveC

ost is King

MarketConsumer Commercial Industrial

ISA SP100.11a

ZigBee® Protocol

WirelessHART™Specification

Synkro™Networking

Protocol


Comparison Table by major features

IndustrialIndustrialConsumer andCommercialTarget Market

GoodBetter*BestBattery Life

Industrial ControlProcess ControlFactory Automation

Smart Energy,Building AutomationTarget Applications

YesYesYesCertification Program

YesYesNoMessage Priority (QOS)HighMediumLowCostYesYesProfileKey Exchange

AES128AES128AES128Encryption

BlacklistBlacklistPreferred channelChannel Blacklist / PreferredChannels

10ms10ms4msLatency

YesYesNoAddressed in FutureSpec

Sleeping Routers

FFDFFD, RFDFFD, RFDDevice TypeMeshMesh, TreeMesh, TreeTopology

HoppingHoppingAgility - 2007 SpecChannel Hopping/Agility200620062003802.15.4

WirelessHART™SpecificationSP100™ZigBee® ProtocolFeature


Table with Pro/Cons

• More costly components required• TDMA mode only

• Deterministic• Immune to Multipath• Sleeping Routers• Existing wired devices in market

WirelessHART™Specification

• More costly components required• Object Structure in the Application Layersadds structure which might be viewed bydevelopers as too restrictive

• Deterministic• Immune to Multipath• Sleeping Routers• CSMA and TDMA tunable• Multiple Fieldbus support• IPv6 Support

SP100.11a

• Not cost effective for high volumeconsumer• Complex• Not “Industrial Grade”

• General market appeal• Lots of backing in Smart Energy space• Products in market today

ZigBee® Protocol

ConsProsTechnology


Questions ?

how zigbee/802.15.4 protocol simplifies wireless m2m ... · long battery life, selectable latency...

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