ZigBee802.15.4 and the ZigBee AllianceMotorola 802.15.4/ZigBee Platform

Contents1. The ZigBee Alliance and 802.15.42. Features of Protocol Stack3. ZigBee and Bluetooth4. Reliability Throughout the Stacks5. Robustness Throughout the Stacks6. 802.15.4/ZigBee vs. Bluetooth7. Motorola 802.15.4/ZigBee Platform8. An Application Example

The ZigBee Alliance and 802.15.4

1. The ZigBee Alliance isA consortium of end users and solution providers, primarily responsible forthe development of the 802.15.4 standardDeveloping applications and network capability utilizing the 802.15.4 packet delivery mechanism Addresses application and interoperability needs of a substantial part of the market2. IEEE 802.15.4 Composed of many of the individuals and companies that make up theZigBee AllianceDeveloped the basic PHY and MAC standard with the requirement that 15.4be simple and manageable and that highlevel functionality (networking,security key management, applications) be considered

ZigBee (1/2)

1. ZigBee is designed to be a low power, low cost, low data rate, wirelesssolution.2. ZigBee relies upon the robust IEEE 802.15.4 PHY/MAC to providereliable data transfer in noisy, interferencerich environments3. ZigBee layers on top of 15.4 with Mesh Networking, Security, andApplications control

ZigBee (2/2)

1. ZigBee Value Propositions Addresses the unique needs of most remote monitoring and control network applications1) Infrequent, low rate and small packet data Enables the broadbased deployment of wireless networks with low cost & low power solutions1) Example: Lighting, security, HVAC,2) Supports peertopeer, star and mesh networks Monitor and sensor applications that need to have a battery life of years on alkaline batteries1) Example security systems, smoke alarms

What is the ZigBee Alliance?1. Organization defining global standards for reliable, costeffective, low power wireless applications2. A rapidly growing, worldwide, nonprofit industry consortium of Leading semiconductor manufacturersTechnology providersOEMsEndusers3. Sensors are one of the reasons for ZigBee!

What is ZigBee technology?1. Costeffective, standardsbased wireless networking solution2. Developed for and targets applications that needlow to moderate data rates and low duty cyclesLow average power consumption / long battery lifeSecurity and reliabilityFlexible and dynamic network topologies1) Star, cluster tree and mesh networksInteroperable application frameworks controlled by anindustry alliance toensureinteroperability/compatibility

The ZigBee Alliance Solution1. Targeted atIndustrial and Commercial control/monitoring systemsWireless sensor systemsHome and Building automation and controlsMedical monitoringConsumer electronicsPC peripherals2. Industry standard through application profiles running over IEEE 802.15.4 radios3. Primary driversSimplicityLong battery lifeNetworking capabilitiesReliabilityLow cost4. Alliance member companies provide interoperability and certificationtesting

Why do we need ZigBee technology?1. ONLY standardsbased technology thatAddresses the unique needs of most remote monitoring and control andsensory network applicationsEnables the broadbased deployment of wireless networks with low cost, low power solutionsProvides the ability to run for years on inexpensive primary batteries for a typical monitoring application

Architecture ObjectivesZigBee Architecture Objectives1. Enables costeffective, low power, reliable devices for monitoring andcontrol2. ZigBees architecture developed to target environments and applicationsbest suited to the technology3. Provide a platform and implementation for wirelessly networked devices4. Ensure interoperability through the definition of application profiles5. Define the ZigBee network and stack models6. Provide the framework to allow a separation of concerns for the specification, design, and implementation of ZigBee devices7. Allow future extension of ZigBee

ZigBee Feature SetZigBee V1.0

Adhoc self forming networks1) Mesh, Cluster Tree and StarLogical Device Types1) Coordinator, Router and End DeviceApplications1) Device and Service Discovery2) Messaging with optional responses3) Home Controls Lighting Profile4) General mechanism to define private ProfilesSecurity1) Symmetric Key with AES1282) Authentication and Encryption at MAC, NWK and Application levels3) Master Keys, Network Keys and Link KeysQualification1) Conformance Certification (Platform and Profile)2) Interoperability Events

How A ZigBee Network Forms1. Devices are preprogrammed for their network functionCoordinator scans to find an unused channel to start a networkRouter (mesh device within a network) scans to find an active channel to join,then permits other devices to joinEnd Device will always try to join an existing network2. Devices discover other devices in the network providing complementary servicesService Discovery can be initiated from any device within the network3. Devices can be bound to other devices offering complementary servicesBinding provides a command and control feature for specially identified setsof devices

ZigBee Address Architecture1. AddressingEvery device has a unique 64 bit MAC addressUpon association, every device receives a unique 16 bit network addressOnly the 16 bit network address is used to route packets within the networkDevices retain their 16 bit address if they disconnect from the network,however, if the LEAVE the network, the 16 bit address is reassignedNWK broadcast implemented above the MAC:1) NWK address 0xFFFF is the broadcast address2) Special algorithm in NWK to propagate the message3) Best Effort or Guaranteed Delivery options4) Radius Limited Broadcast feature

Packet Structure1. Packet FieldsPreamble (32 bits) synchronizationStart of Packet Delimiter (8 bits) specifies one of 3 packet typesPHY Header (8 bits) Sync Burst flag, PSDU lengthPSDU (0 to 127 bytes) Data

General Data Packet Structure

ZigBee Network Model

1. Star networks support a single ZigBee coordinator with one or moreZigBee End Devices (up to 65,536 in theory)2. Mesh network routing permits path formation from any source deviceto any destination device

Wireless Networking Basics1. Network ScanDevice scans the 16 channels to determine the best channel to occupy.2. Creating/Joining a PANDevice can create a network (coordinator) on a free channel or join an existing network3. Device DiscoveryDevice queries the network to discover the identity of devices on active channels4. Service DiscoveryDevice scans for supported services on devices within the network5. BindingDevices communicate via command/control messaging

Network Pieces PAN Coordinator1. PAN Coordinatorowns the network1) Starts it2) Allows other devices to join it3) Provides binding and addresstableservices4) Saves messages until they can bedelivered5) And more could also have i/ocapabilityA fullfunction device FFDMains powered

Network Pieces Router1. RoutersRoutes messagesDoes not own or start network1) Scans to find a network to joinGiven a block of addresses to assignA fullfunction device FFDMains powered depending on topologyCould also have i/o capability

Network Pieces End Device1. End DeviceCommunicates with a single deviceDoes not own or start network1) Scans to find a network to joinCan be an FFD or RFD (reduced function device)Usually battery powered

Battery Life1. ZigBee protocol was designed from the ground up to support very long life battery applications2. Users can expectNearshelf life in a typical monitoring application3. Battery life is ultimately a function ofbattery capacity and application usage4. Many industrial applications are in harsh thermal environmentsBatteries may include alkalines or LiprimariesOther forms of power generation might include solar, mechanical,piezoelectric

IEEE 802.15 Working Group

Comparison between WPAN

IEEE 802.15.4 Standard

Device to Coordinator

Coordinator to Device

Channel Access Mechanism1. Two type channel access mechanism:In nonbeaconenabled networks- unslotted CSMA/CA channel access mechanismIn beaconenabled networks - slotted CSMA/CA channel access mechanism

IEEE 802.15.4

The 802.15.4 / Zigbee Sandbox

The Application Space

Development of the Standard1. ZigBee Alliance50+ companies: semiconductor mfrs, IP providers, OEMs, etc.Defining upper layers of protocol stack: from network to application, including application profilesFirst profiles published mid 20032. IEEE 802.15.4 Working GroupDefining lower layers of protocol stack: MAC and PHY scheduled for release in April

Stack Reference Model (1/2)

ZigBee and BluetoothZigBeeSmaller packets over largenetworkMostly Static networks withmany, infrequently used devicesHome automation, toys, remote controls, etc.BluetoothLarger packets over small networkAdhoc networksFile transferScreen graphics, pictures, handsfree audio, Mobile phones, headsets, PDAs, etc

Timing ConsiderationsZigBee:Bluetooth:Network join time = 30ms typicallySleeping slave changing to active = 15ms typicallyActive slave channel access time = 15ms typicallyNetwork join time = >3sSleeping slave changing to active = 3s typicallyActive slave channel access time = 2ms typically

Comparison OverviewBluetoothZigBee.

Product Examples

Home & Diagnostics Examples

ZigBee Alliance Member