Zigbee Seminar Report- Jitu

Fourth Year Seminar Report

Zigbee

By

Jitendra Kumar Sahoo

8th

Semester

Redg. No. – 0701216120

Department of Electronics and Telecommunication

Padmanava College of Engineering

Rourkela-796002

Abstract

Zigbee is a new Wireless sensor network technology characteristic of less distance and lowspeed. It can be used in some special situation for signal collection, processing and trans-mitting.ZigBee is a technology now being deployed for wireless sensor networks. A sensornetwork is an infrastructure comprised of sensing, computing and communications elementsthat allows the administrator to instrument, observe and react to events and phenomena ina specified environment.Typical applications include, but are not limited to, data collection,monitoring, surveillance and medical telemetry.

ZigBee is the set of specifications built around the IEEE 802.15.4 wireless protocol.ZigBee technology is a low data rate, low power consumption, low cost, wireless networkingprotocol targeted towards automation and remote control applications

ZigBee is a communication protocol that uses small, low-power digital radio signals basedon the IEEE 802.15.4 standard.ZigBee operates in

ISM radio bands: In USA 915 MHz, in Europe 868 MHz and 2.4 GHz in other parts ofthe globe. In the 2.4 GHz band there are 16 ZigBee channels, with each channel requiring 2MHz of bandwidth.

The most capable ZigBee node type is said to require only about 10typical Bluetoothor Wireless Internet node, while the simplest nodes are about 2However, actual code sizesare much higher, closer to 50transmission range of Zigbee is over 50 meters and speed is20-250KB/s, it needs only 32K of system resources. It is simple, effective and cheaper thanother WPANs like bluetooth, WiFi. ZigBee solves the needs of remote monitoring andcontrol, and sensor network applications. It takes full advantage of a powerful physical radiospecified by IEEE802.15.4, adding logical network, security and application software to thespecification.

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Contents

1 Introduction 11.1 What is Zigbee? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Origin of word Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Zigbee Alliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.4 Need of Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.5 Wireless sensor networking is one of the most exciting technology markets today 21.6 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.7 Software and hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Protocol stack for Zigbee 62.1 PHYSICAL layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.1 Features of PHY layer: . . . . . . . . . . . . . . . . . . . . . . . . . . 72.2 MAC layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.2.1 Different mac layer devices . . . . . . . . . . . . . . . . . . . . . . . . 72.3 Network Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.3.1 Network layer topologies . . . . . . . . . . . . . . . . . . . . . . . . . 92.3.2 Mesh topology in Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 Benefits of Mesh topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.5 Limitations of Mesh topology . . . . . . . . . . . . . . . . . . . . . . . . . . 102.6 The power of Mesh Topology . . . . . . . . . . . . . . . . . . . . . . . . . . 102.7 Cluster tree topology in Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . 102.8 Star topology in Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.9 Benefits of Star topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.10 limitation of Star topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.11 Application layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.12 Reliable ZigBee Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.13 Security in Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.13.1 Trust center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.13.2 Security keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.13.3 Master keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.13.4 Network keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.13.5 Link keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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2.14 Security modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.14.1 Standard security mode . . . . . . . . . . . . . . . . . . . . . . . . . 142.14.2 High security mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142.14.3 Difference between Zigbee and Bluetooth . . . . . . . . . . . . . . . . 14

3 Zigbee - Protocol,Devices and Applications 163.1 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163.2 What ZigBee’s ”Low Power Consumption” Means . . . . . . . . . . . . . . 163.3 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.4 Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.5 Disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.6 Applications of Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Conclusion 19

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List of Figures

2.1 Zigbee protocol stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.2 Mac layer association . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.3 Mesh Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.4 Star Topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.5 Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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List of Tables

2.1 Difference between Bluetooth and Zigbee . . . . . . . . . . . . . . . . . . . . 15

Chapter 1

Introduction

1.1 What is Zigbee?

Zigbee is a Technological Standard Created for Control and Sensor Networks based on theIEEE 802.15.4 specification for wireless personal area network .It is a New wireless technologythat has application in various fields.Zigbee benfits are low cost and Range and obstructionissues avoidance.The main features of this standard are network flexibility, low cost, very lowpower consumption, and low data rate in an adhoc self-organizing network among inexpensivefixed, portable and moving devices.

1.2 Origin of word Zigbee

The erratic, zig-zagging patterns of bees between flowers while collecting pollens from theflowers Symbolizes communication between nodes in a mesh network of Zigbee network.Thenetwork components are analogous to queen bee, drones, worker bees.

Process on ZigBee-style networks began in 1998, when many engineers realized that bothWiFi and Bluetooth were going to be unsuitable for many applications. In particular, a needfor self-organizing ad-hoc digital radio networks arose.

ZigBee is very low cost, low power consumption, two ways, wireless communication pro-tocol. It adopts IEEE 802.15.4, as its lower protocol layers: the physical layer (PHY) andmedium Access Control (MAC) portion of data link layer (DLL) takes care of network, secu-rity and upper application issues. The relative organization of the IEEE radio with respectto the ZigBee functionality. Wireless systems mostly use cell phone-style radio links, usingpoint-to-point or point-to- multipoint transmission. These traditional wireless formats havedrawbacks like rigid structure, signal dropping and meticulous planning requirements.

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1.3 Zigbee Alliance

It is association of companies working together to enable reliable ,cost effective, low power,wirelessly networked ,monitoring and control products based on an open global standard.

1.4 Need of Zigbee

ZigBee was created to satisfy the market’s need of a standards-based wireless network thatis cost-effective,supports low data rates,low power consumption,secure and reliable.

Why ZigBee? Let us compare it to its closest competitor, Bluetooth. If we want to builda remote battery powered Bluetooth node, we need at least 250K of memory for the codeand stack, and transmission speed of 720KB/s up to range of approximately 10 meters ,if there are no cordless phones, VCRs etc around. The battery life will be 7 days. Now,compare that to

ZigBee. Though it is a lower-speed wireless protocol that’s targeted at transmissionspeeds of 20-250KB/s, it has a transmission range of over 50 meters. Battery life is 2 yearsand 32K of system resources is required. This is simple, effective, and very practica

ZigBee is the only wireless standards-based technology that addresses the unique needsof remote monitoring control, and sensory network applications,enables broad-based deploy-ment of wireless networks with low cost, low power solutions.

1.5 Wireless sensor networking is one of the most ex-

citing technology markets today

[4]. They say that over the next five to ten years, wireless sensors will have a significantimpact on almost all major industries as well as our home lives. Broadly, this technologymarket includes application segments such as automated meter reading, home automation,building automation, container security/tracking, and many others.

Although products that span these application segments are diverse and different in howthey operate and what they do, their requirements from a wireless communication technologyare very similar. For example, these applications generally require low data rates and arebattery powered.

The main motivations for migrating these products to wireless communications are three-fold:

1. Installation cost - The cost of running wires in a typical building automation projectin an existing facility can be as high as 80project cost [4]. 2. Maintenance - It is easier toconfigure a hot-water heater controller with a hand-held remote than a keypad in the closet.3. New markets - Eliminating the wire opens new markets that were previously unavailableto wired products.

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Zigbee [3, 5] was introduced as an alternative to Bluetooth for devices with low powerconsumption requirements and applications of lower bit rates. Although products based onthe Bluetooth standard are often capable of operating at greater distances, the targetedoperational area is the one around an individual, (e.g. within a 10 meters diameter). Blue-tooth utilizes a short range radio link that operates in the 2.4 GHz industrial scientific andmedical (ISM) band similar to WLAN. However, the radio link in Bluetooth is based onfrequency hop spread spectrum. Although at any point in time, the Bluetooth signal oc-cupies only 1MHz, the signal changes the center frequency (or hops) deterministically at arate of 1600Hz. Bluetooth hops over 79 center frequencies, so over time the Bluetooth signalactually occupies 79MHz. The new short range, low power, low rate wireless networkingprotocol, Zigbee, complements the high data rate technologies such as WLAN and open thedoor for many new applications. This standard operates at three bands, the 2.4 GHz bandwith a maximum rate of 250 kbps, the 915 MHz band with a data rate of 40 kbps, and the868 MHz band with a data rate of 20 kbps. While Bluetooth devices are better suited forfairly high rate sensor and voice applications, Zigbee is better suited for low rate sensors anddevices used for control applications that do not require high data rate but must have longbattery life, low user interventions and mobile topology. Some of these applications are inthe fields of medicine

ZigBee is a low-cost, low-power, wireless mesh networking proprietary standard. The lowcost allows the technology to be widely deployed in wireless control and monitoring applica-tions, the low power-usage allows longer life with smaller batteries, and the mesh networkingprovides high reliability and larger range. The ZigBee Alliance, the standards body thatdefines ZigBee,[1] also publishes application profiles that allow multiple OEM vendors tocreate interoperable products. The current list of application profiles either published orin the works are: Home Automation ZigBee Smart Energy 1.0/2.0 Commercial BuildingAutomation Telecommunication Applications Personal, Home, and Hospital Care Toys

The relationship between IEEE 802.15.4 and ZigBee is similar to that between IEEE802.11 and the Wi-Fi Alliance. The ZigBee 1.0 specification was ratified on 14 December2004 and is available to members of the ZigBee Alliance. Most recently, the ZigBee 2007specification was posted on 30 October 2007. The first ZigBee Application Profile, HomeAutomation, was announced 2 November 2007. As amended by NIST, the Smart EnergyProfile 2.0 specification will remove the dependency on IEEE 802.15.4. Device manufactur-ers will be able to implement any MAC/PHY, such as IEEE 802.15.4(x) and IEEE P1901,under an IP layer based on 6LowPAN.

ZigBee operates in the industrial, scientific and medical (ISM) radio bands; 868 MHz inEurope, 915 MHz in the USA and Australia, and 2.4 GHz in most jurisdictions worldwide.The technology is intended to be simpler and less expensive than other WPANs such asBluetooth. ZigBee chip vendors typically sell integrated radios and microcontrollers withbetween 60K and 128K flash memory, such as the Jennic JN5148, the Freescale MC13213,

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the Ember EM250, the Texas Instruments CC2430, the Samsung Electro-Mechanics ZBS240and the Atmel ATmega128RFA1. Radios are also available stand-alone to be used withany processor or microcontroller. Generally, the chip vendors also offer the ZigBee softwarestack, although independent ones are also available. Because ZigBee can activate (go fromsleep to active mode) in 15 msec or less, the latency can be very low and devices can be veryresponsive particularly compared to Bluetooth wake-up delays, which are typically aroundthree seconds. [2] Because ZigBees can sleep most of the time, average power consumptioncan be very low, resulting in long battery life. The first stack release is now called ZigBee2004. The second stack release is called ZigBee 2006, and mainly replaces the MSG/KVPstructure used in 2004 with a ”cluster library”. The 2004 stack is now more or less obso-lete.[citation needed] ZigBee 2007, now the current stack release, contains two stack profiles,stack profile 1 (simply called ZigBee), for home and light commercial use, and stack profile2 (called ZigBee Pro). ZigBee Pro offers more features, such as multi-casting, many-to-onerouting and high security with Symmetric-Key Key Exchange (SKKE), while ZigBee (stackprofile 1) offers a smaller footprint in RAM and flash. Both offer full mesh networking andwork with all ZigBee application profiles.[citation needed] ZigBee 2007 is fully backwardcompatible with ZigBee 2006 devices: A ZigBee 2007 device may join and operate on a Zig-Bee 2006 network and vice versa. Due to differences in routing options, ZigBee Pro devicesmust become non-routing ZigBee End-Devices (ZEDs) on a ZigBee 2006 or ZigBee 2007network, the same as ZigBee 2006 or ZigBee 2007 devices must become ZEDs on a ZigBeePro network. The applications running on those devices work the same, regardless of thestack profile beneath them.

1.6 Uses

ZigBee protocols are intended for use in embedded applications requiring low data rates andlow power consumption. ZigBee’s current focus is to define a general-purpose, inexpensive,self-organizing mesh network that can be used for industrial control, embedded sensing, med-ical data collection, smoke and intruder warning, building automation, home automation,etc. The resulting network will use very small amounts of power individual devices musthave a battery life of at least two years to pass ZigBee certification.

Typical application areas includeHome Entertainment and Control Smart lighting, advanced temperature control, safety andsecurity, movies and musicHome Awareness Water sensors, power sensors, energy monitoring, smoke and fire detectors,smart appliances and access sensorsMobile Services m-payment, m-monitoring and control, m-security and access control, m-healthcare and tele-assistCommercial Building Energy monitoring, HVAC, lighting, access controlIndustrial Plant Process control, asset management, environmental management, energymanagement, industrial device control

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1.7 Software and hardware

The software is designed to be easy to develop on small, inexpensive microprocessors. Theradio design used by ZigBee has been carefully optimized for low cost in large scale produc-tion. It has few analog stages and uses digital circuits wherever possible.Even though the radios themselves are inexpensive, the ZigBee Qualification Process involvesa full validation of the requirements of the physical layer. This amount of concern about thePhysical Layer has multiple benefits, since all radios derived from that semiconductor maskset would enjoy the same RF characteristics. On the other hand, an uncertified physicallayer that malfunctions could cripple the battery lifespan of other devices on a ZigBee net-work. Where other protocols can mask poor sensitivity or other esoteric problems in a fadecompensation response, ZigBee radios have very tight engineering constraints: they are bothpower and bandwidth constrained. Thus, radios are tested to the ISO 17025 standard withguidance given by Clause 6 of the 802.15.4-2006 Standard. Most vendors plan to integratethe radio and microcontroller onto a single chip.

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Chapter 2

Protocol stack for Zigbee

Zigbee protocol stack mainly consists of PHY and MAC layer from IEEE 802.15.4 stan-dard,Network layer,Application layer.?

Figure 2.1: Zigbee protocol stack

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2.1 PHYSICAL layer

ZigBee operates in one of three license free bands 2.4 GHz, 915 MHz for North America, and868 MHz for Europe.At 2.4 GHZ, there are a total of 16 channels available with a maximumdata transfer of 250 kbps.At 915 MHz: 10 channels for a max 40 kbps transfer rate.At 868MHz: 1 channel for a max 20 kbps transfer rate.

2.1.1 Features of PHY layer:

1. Activation and deactivation of the radio transceiver.

2. energy detection -Here the power of received signal is estimated within bandwidth ofchannel .It is used in network layer for channel selection.

3. Link quality indication (LQI)-This indicator shows the quality of the link betweendevices within a Zigbee.It is characterization of strength or quality of received packet.

4. Clear channel assessment (CCA)-It is performed to detect if the channel is busy is orempty.A mode in CCA performs the RF energy detection with other wireless networkis avoided.

5. Channel selection.

2.2 MAC layer

Mac layer control access to the radio channel.Its responsibilities are transmitting beaconframes,synchroinisation and providing a reliable transmission.

2.2.1 Different mac layer devices

1. Full function device(FFD):

A network device that extends network area coverage, dynamically routes around ob-stacles ,and provides backup routes in case of network congestion or device.

2. Reduced function device(RFD)

A network device that can start or receive a message but cannot forward messagesupstream or downstream.It can communicate with the co-ordinator or a router,butnot directely with other end devices.

3. PAN co-ordinator

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Figure 2.2: Mac layer association

It is controller of a network that is responsible for the network formation and main-tanance.The PAN co-ordinator must be a router.

4. MAC Layer association

On the power on of end device it sends beacon request.Beacon is a transmission bya Zigbee router to confirm their presence o other network devices.PAN coordinatorsends the beacon.Then end device requests for the association.PAN co-ordinator checkswheather enough resourses are present or not if present it sends acknowledgement.andassociation is established between PAN co-ordinator and end device.

2.3 Network Layer

1. Discovery of route and maintenance.

2. Routing of message

3. Clear channel assessment (CCA)-It is performed to detect if the channel is busy is orempty.A mode in CCA performs the RF energy detection with other wireless network

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is avoided.

4. Network management and addressing.

2.3.1 Network layer topologies

Zigbee can work in 3 topologies

1. Mesh topology

2. Cluster tree topology

3. Star topology

2.3.2 Mesh topology in Zigbee

Figure 2.3: Mesh Topology

Mesh topology,also called peer-to-peer, consists of a mesh of interconnected routers andend. Each router is typically connected through atleast two pathways, and can relay messagesfor its neighbors.Mesh topology supports ”multi-hop”communications, through which datais passed by hopping from device to device using the most reliable communication links andmost cost-effective pathuntil its destination is reached.The multi-hop ability also helps toprovide fault tolerance, in that if one device fails or experiences interference, the networkcan reroute itself using the remaining devices.

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2.4 Benefits of Mesh topology

1. This topology is highly reliable and robust.Should any individual router become inac-cessible, alternative routes can be discovered and used.

2. The use of intermediary devices in relaying data means that the range of the networkcan be significantly increased, making this topology highly scalable.

3. Weak signals and dead zones can be eliminated by simply adding more routers to thenetwork.

2.5 Limitations of Mesh topology

1. This topology has a higher communications overhead than the star topology, whichcan result in increased latency and lower end-to-end performance.

2. Meshed routing requires more complex network protocols. This means the routersrequire more embedded resources, which can result in

3. increased power consumption and costs.

2.6 The power of Mesh Topology

Mesh networking was not created specifically for wireless sensor networks. This networktopology is already hard at work in both the public switched telephone network (PSTN) andthe Internet. The mesh is the best way to achieve the resiliency and scalability demandedfrom these mission-critical public networks.Examining the key benefits that mesh topologiesprovide in a bit more detail will help to explain why it is such an appropriate choice formany wireless sensor networks.

2.7 Cluster tree topology in Zigbee

The cluster tree topology is less efficient than the other two, and is therefore rarely (if ever)implemented.

2.8 Star topology in Zigbee

In a Star topology, also called point-to-point, all devices are within direct communicationrange to the coordinator, through which all messages are routed.A device sends a messageto the coordinator, which then passes it on to the destination device. Direct communication

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Figure 2.4: Star Topology

between the end devices is not supported.

2.9 Benefits of Star topology

1. Its simplicity means that this topology does not require a complex network layer orrouting protocols

2. Performance is generally high, with packets taking a maximum of two hops to reachtheir destination.

2.10 limitation of Star topology

1. )There are no alternative paths between the device and coordinator, so if a path be-comes obstructed, communication is lost between the device and coordinator

2. )The radius of the network is limited by the radio range between the coordinator andchild devices (typically 30-100 meters).

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2.11 Application layer

Application layer mainly consists of Application support sublayer,Application frameworkand Zigbee device objects

Application Support sublayer-The portion of the Application Layer responsible for pro-viding a data service to the application and ZigBee device profiles. In addition, it providesa management service to maintain binding links and the storage of the binding table itself.

Application framework-The portion of the Application Layer that provides a descriptionof how to build a profile onto the ZigBee stack so that profiles can be generated in a consistentmanner. It also specifies a range of standard data types for profiles, descriptors to assistin service discovery, frame formats for transporting data, and a key value pair construct torapidly develop simple, attribute based profiles.

Zigbee device objects-The portion of the ZigBee Application Layer responsible for defin-ing the role of the device within the network (e.g. coordinator, router, or end device),initiating and/or responding to binding and discovery requests, and establishing a securerelationship between network devices. It also provides a rich set of management commands,defined in the ZigBee Device Profile (ZDP).

2.12 Reliable ZigBee Networks

ZigBee is a broad-based standard that is intended to cover a range of applications andcompeting requirements. Figure 1 shows an example of the range of target markets typicallydiscussed for ZigBee.

2.13 Security in Zigbee

ZigBee security, which is based on a 128-bit AES algorithm, adds to the security modelprovided by IEEE 802.15.4. ZigBee’s security services include methods for key establishmentand transport, device management, and frame protection.The ZigBee specification definessecurity for the MAC, NWK and APS layers. Security for applications is typically providedthrough Application Profiles.

2.13.1 Trust center

The Trust Center decides whether to allow or disallow new devices into its network.TheTrust Center may periodically update and switch to a new Network Key. It first broadcaststhe new key encrypted with the old Network Key. Later, it tells all devices to switch tothe new key. The Trust Center is usually the network coordinator, but is also able to be adedicated device. It is responsible for the following security roles:

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Figure 2.5: Network

1. Trust Manager, to authenticate devices that request to join the network

2. Network Manager, to maintain and distribute network keys

3. Configuration Manager, to enable end-to-end security between devices

2.13.2 Security keys

ZigBee uses three types of keys to manage security: Master, Network and Link.

2.13.3 Master keys

These optional keys are not used to encrypt frames. Instead, they are used as an initialshared secret between two devices when they perform the Key Establishment Procedure(SKKE) to generate Link Keys.Keys that originate from the Trust Center are called TrustCenter Master Keys, while all other keys are called Application Layer Master Keys.

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2.13.4 Network keys

These keys perform security Network Layer security on a ZigBee network. All devices ona ZigBee network share the same key.High Security Network Keys must always be sent en-crypted over the air, while Standard Security Network Keys can be sent either encrypted orunencrypted. Note that High Security is supported only for ZigBee.

2.13.5 Link keys

These optional keys secure unicast messages between two devices at the Application Layer.Keysthat originate from the Trust Center are called Trust Center Link Keys, while all other keysare called Application Layer Link Keys.

2.14 Security modes

ZigBee offers two different security modes: Standard and High.

2.14.1 Standard security mode

In Standard Security mode, the list of devices, master keys, link keys and network keys canbe maintained by either the Trust Center or by the devices themselves. The Trust Center isstill responsible for maintaining a standard network key and it controls policies of networkadmittance. In this mode, the memory requirements for the Trust Center are far less thanthey are for High Security mode.

2.14.2 High security mode

In High Security mode, the Trust Center maintains a list of devices, master keys, link keysand network keys that it needs to control and enforce the policies of network key updatesand network admittance. As the number of devices in the network grows, so too does thememory required for the Trust Center.

The additional security capabilities inherent in ZigBee PRO are critical as ZigBee isused in increasingly important applications. The control of critical systems infrastructure,whether in a commercial building, utility grid, industrial plant, or a home security systemmust not be compromised. ?

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Table 2.1: Difference between Bluetooth and Zigbee

Characteristics Bluetooth ZigbeeRange 10-100m 30-100m.Latency 10sec 30ms.Extendibility yes noComplexity complex simpleSecurity PIN 64bit,128bit 128bit AESBattery life Short long

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2.14.3 Difference between Zigbee and Bluetooth

Bluetooth and ZigBee have much in common. Both are types of IEEE 802.15 wirelesspersonal-area networks,” or WPANs. Both run in the 2.4-GHz unlicensed frequency band,and both use small form factors and low .

Chapter 3

Zigbee - Protocol,Devices andApplications

3.1 Protocol

The protocols are built on recent algorithmic research to construct a low-speed ad-hoc net-work of nodes automatically. In large network instances, the network will be a cluster ofclusters in the form of a mesh or a single cluster. ZigBee protocols minimize the time forwhich the radio is on to reduce the power use. The current profiles derived from the ZigBeeprotocols support beacon and non-beacon enabled networks.

In beacon enabled networks, the special network nodes called ZigBee Routers transmitperiodic beacons to confirm their presence to other network nodes. Beacon Oriented net-works use Guaranteed Time Slots (GTS). Nodes are active only when a beacon is beingtransmitted.They may sleep between beacons, that will lower the duty cycle and increasethe battery life.The intervals may range from 15.36 milliseconds to

3.2 What ZigBee’s ”Low Power Consumption” Means

ZigBee’s low power consumption is rooted not in RF power, but in a sleep mode specificallydesigned to accommodate battery powered devices. Any ZigBee-compliant radio can switchautomatically to sleep mode when it’s not transmitting, and remain asleep until it needsto communicate again. For radios connected to battery-powered devices, this results in ex-tremely low duty cycles and very low average power consumption.

When a radio is in sleep mode, its RF power rating is irrelevant; it’s only when transmit-ting that its RF power affects power consumption. In the case of Cirronet’s ZigBee solutions,a radio with 100 mW RF power will typically consume 150 mA at 3.3 V when transmitting,

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compared to 75 mA at 3.3 V for a radio with 1 mW RF power. The 100 mW radio consumestwice as much power - but only when actively transmitting. As long as the high power radio’slow noise amplifier is turned off, power consumption while sleeping is roughly equivalent tothat of a low power radio.

If the high RF power radio is awake and transmitting 5very active radio, the extra averagepower consumption is roughly 5power consumption means that a battery that would last forfive years with a 1 mW radio would last four years and nine months with a 100 mW radio.As this illustrates, ZigBee radios with higher RF output ratings are still excellent candidatesfor use with battery powered devices.

It’s important to note that the ZigBee Alliance doesn’t itself specify anything for RFpower. ZigBee’s RF power specification comes from IEEE 802.15.4, which specifies a min-imum power output rating of 1 mW, with no specified maximum. The de facto 100 mW”high power” level relates to the European limit of 100 mW EIRP, including antenna gain.

3.3 Types

There are three different types of ZigBee device:

1. ZigBee coordinator (ZC): The most capable device, the coordinator forms the root ofthe network tree and might bridge to other networks. There is exactly one ZigBee co-ordinator in each network. It is able to store information about the network, includingacting as the repository for security keys.

2. ZigBee Router (ZR): Routers can act as an intermediate router, passing data fromother devices.

3. ZigBee End Device (ZED): Contains just enough functionality to talk to its parentnode (either the coordinator or a router); it cannot relay data from other devices.

3.4 Advantages

1. ZigBee’s main advantage is its ability to be configured in so-called mesh networks withwireless nodes that are capable of multi-year battery lives.

2. Zigbee Supports large no of nodes in network.

3. Zigbee has Low latency period.It is around 30ms.

4. Power consumption in zigbee is very low as compared to other wireless sensor networktechnologes hence long battery life.

5. Low cost

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6. It Can be used globally since Zigbee alliance is an open global standard source.

7. Zigbee network designs are simple.

3.5 Disadvantages

1. It works over short range.

2. Data rate is low.

3.6 Applications of Zigbee

1. Home Automation-The ZigBee Home Automation profile is likely to be the first ZigBeeapplication profile to hit the marketplace in volume and also holds promise to be thefirst application space where multiple products from multiple vendors are truly inter-operable allowing users to mix and match products to enhance their digital lifestyle.Lighting control, thermostats, occupancy and motion sensors, security systems, doorand window sensors, as well as fixed and mobile keypads all occupy the ZigBee homeautomation space and can be bound together to make sophisticated home automationbehaviors.

2. Building automation-Wireless sensing and control mesh networks can make buildingautomation easier and more efficient by combining lighting,HVAC, security, safety sys-tems, and other monitoring networks into a single platform.

3. Industrial plant monitoring-Wireless sensing and control mesh networks provide accu-rate and efficient IPM, and are also ideal to deploy in hazardous environments in whichyou want to minimize human exposure.

4. PC and peripherals-PC and peripherals like mouse,keyboard,joystic can be automated.

5. personel health care-Patient monitoring,remote diagnosis are incuded in personel healthcare applications.

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Chapter 4

Conclusion

Comparing ZigBee technology with the other present technology it is evident that ZigBeecan have a safe future in this effervescent world of technology.There is definitely a place onthe market for ZigBee, since no global standard exists today in the wireless sensor networkarea.ZigBee is the specification of a low-cost, low-power wireless communications solution, meantto be integrated as the main building block of ubiquitous networks. It is maintained by theZigBee Alliance, which develops the specification and certifies its proper implementation.As of 2007, the latest publicly available revision is the 2006 version.

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