b209013 seminar report 1

7/31/2019 B209013 Seminar Report 1

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A

Seminar ReportOn

ZIGBEE- THE FUTURE OF WIRELESS

CONTROL

By

Biswajit Sahoo

DEPARTMENT OF ELECTRONICSANDTELECOMMUNICATIONENGINEERING

International Institute of Information Technology Bhubaneswar,Gothapatna, Bhubaneswar -751003

[2012 2013]


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i

A

Seminar ReportOn

ZIGBEE-THE FUTURE OF WIRELESS CONTROL

In partial fulfillment of requirements for the degree of

Bachelor of Technology

In

Electronics and Telecommunication Engineering

SUBMITTED BY:

Biswajit Sahoo

Under the Guidance of

Prof. Rajat Kumar Giri

DEPARTMENT OF ELECTRONICSAND TELECOMMUNICATION ENGINEERING

International Institute of Information Technology - BhubaneswarGothapatna, Bhubaneswar -751003

[2012

2013]


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iii

ACKNOWLEDGEMENT

Many people have contributed to the success of this. I take this opportunity to

express my gratitude to the people who have been instrumental in the successful

completion of this project.

I would like to gratefully acknowledge Prof. Harish Kumar Sahoo, Seminar

Coordinator, for his support and guidance right from the concept till

implementation.

I am profoundly indebted to my seminar guide Prof. Rajat Kumar Giri, for

innumerable acts of timely advice, encouragement and I sincerely express my

gratitude to him.

I express my immense pleasure and thankfulness to all the teachers and staff of the

Department of Electronics and Telecommunication Engineering, IIIT

Bhubaneswar for their cooperation and support.

Last but not the least, I thank all others, and especially my parents and classmates

who in one way or another helped me in the successful completion of this work.


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iv

INDEX PAGE

TOPIC Page No.

ABSTRACT 1

1 Introduction

1.1 What is Zigbee? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Origin of word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3 Zigbee Alliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.4 Need of Zigbee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.5 Wireless sensor networking is one of the most exciting technology

markets today . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 4

1.6 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.7 Software and H ardwarre . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2 Protocol stackfor Zigbee

2.1 Physical layer . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.1.1 Features of PHY layer: . . . . . . . . . . . . . . . . . . . 1 0

2.2 MAC layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2.1 Different MAC layer devices . . . . . . . . . . . . . . . . 11

2.3 Network Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.3.1 Network layer .. . . . . . . . . . . . . . . . . . . . . 13

2.3.2 Mesh topology in .. .. . . . . . . . . . . . . . . . . . . 14

2.4 Benefits of Mesh topology . . .. . . . . . . . . . . . . . . . . . . . . 14

2.5 Limitations of Mesh topology .. . . . . . . . . . . . . . . . . . . . . 15

2.6 The power of Mesh Topology .. . . . . . . . . . . . . . . . . . . . . 15

2.7 Cluster tree topology in Zigbee .. . . . . . . . . . . . . . . . . . . . . 15

2.8 Star topology in Zigbee .. . . . . . . . . . . . . . . . . . . . . 15

2.9 Benefits of Star topology .. . . . . . . . . . . . . . . . . . . . . 16


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2.10 Limitation of Star topology . .. . . . . . . . . . . . . . . . . . . . . . 16

2.11 Application layer . . . . . .. . . . . . . . . . . . . . . . . . . . . . 17

2.12 Reliable ZigBee Networks . .. . . . . . . . . . . . . . . . . . . . . . 17

2.13 Security in Zigbee . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 182.13.1 Trust center . . . . . .. . . . . . . . . . . . . . . . . . . . . . 18

2.13.2 Security keys . . . . .. . . . . . . . . . . . . . . . . . . . . . 19

2.13.3 Master keys . . . . . .. . . . . . . . . . . . . . . . . . . . . . 20

2.13.4 Network keys . . . . .. . . . . . . . . . . . . . . . . . . . . . 20

2.13.5 Link keys . . . . . . .. . . . . . . . . . . . . . . . . . . . . . 20

2.14 Security modes . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.14.1 Standard security mode . . . . . . . . . . . . . . . . . . . 20

2.14.2 High security mode . . . . . . . . . . . . . . . . . . . . . 20

2.14.3 Difference between Zigbee and Bluetooth . . . . . . . . . 21

3 Zigbee - Protocol, Devices and Applications

3.1 Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

3.2 What ZigBeesLow Power Consumption Means . . . . . . . 22

3.3 Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 33.4 Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3.5 Disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3.6 Modes of operation . . . . . . . . . . . . . . . . . . . . . . . . 24

3.7 Applications of Zigbee . . . . . . . . . . . . . . . . . . . . . 25

3.8 Competent technologies. . . . . . . . . . . . . . . . . . . . . . 26

4 Conclusion.. 275 Bibliography 28

6 Glossary 32


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TABLE INDEX

Table Page No.

1. Table 2.1- Difference between Bluetooth and Zigbee 21


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FIGURE INDEX

Figure Page No.

1. Figure 2.1 Zigbee protocol stack.. 10

2. Figure 2.2 Mac layer association . 12

3. Figure 2.3 Mesh Topology..14

4. Figure 2.4 Star Topology..16

5. Figure 2.5 Network.19


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1

ABSTRACT

ZigBee is an IEEE 802.15.4 standard for data communications with business and

consumer devices. It is designed around low-power consumption allowing

batteries to essentially last forever. The ZigBee standard provides network,

security, and application support services operating on top of the IEEE 802.15.4

Medium Access Control (MAC) and Physical Layer (PHY) wireless standard. It

employs a suite of technologies to enable scalable, self-organizing, self-healing

networks that can manage various data traffic patterns. ZigBee is a low-cost, low-

power, wireless mesh networking standard. The low cost allows the technology to

be widely deployed in wireless control and monitoring applications, the low

power-usage allows longer life with smaller batteries, and the mesh networking

provides high reliability and larger range. ZigBee has been developed to meet the

growing demand for capable wireless networking between numerous low power

devices. In industry ZigBee is being used for next generation automated

manufacturing, with small transmitters in every device on the floor, allowing for

communication between devices to a central computer. This new level of

communication permits finely-tuned remote monitoring and manipulation. Typical

application areas include: home entertainment and control, home awareness,

mobile services, commercial building, industrial plant. There are three different

types of ZigBee devices: ZigBee Coordinator(ZC), ZigBee Router(ZR), ZigBee EndDevice(ZED).


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Zigbee-The future of wireless control

2 Introduction

1. Introduction

1.1 What is Zigbee?

Zigbee is a Technological Standard Created for Control and Sensor Networks

based on the IEEE 802.15.4 specification for wireless personal area network .It

is a New wireless technology that has application in various fields. Zigbee

benefits are low cost and Range and obstruction issues avoidance. The main

features of this standard are network flexibility, low cost, very low power

consumption, and low data rate in an ad-hoc self-organizing network among

inexpensive fixed, portable and moving devices.

1.2 Origin ofword Zigbee

The erratic, zig-zagging patterns of bees between flowers while collecting

pollens from the flowers Symbolizes communication between nodes in a mesh

network of Zigbee network. The network components are analogous to queen

bee, drones, worker bees.

Process on ZigBee-style networks began in 1998, when many engineers

realized that both Wi-Fi and Bluetooth were going to be unsuitable for many

applications. In particular, a need for self-organizing ad-hoc digital radio

networks arose.

ZigBee is very low cost, low power consumption, two ways, wireless

communication protocol. It adopts IEEE 802.15.4, as its lower protocol

layers: the physical layer (PHY) and Medium Access Control (MAC) portion

of data link layer (DLL) takes care of network, security and upper application

issues. The relative organization of the IEEE radio with respect to the ZigBee

functionality. Wireless systems mostly use cell phone-style radio links, using


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3 Introduction

point-to-point or point-to- multipoint transmission. These traditional wireless

formats have drawbacks like rigid structure, signal dropping and meticulous

planning requirements.

1.3 History of ZigBee & ZigBee-Alliance

The name ZigBee means erratic, zigzagging patterns of bees between flowers

which symbolizes communication between nodes in a mesh network where the

network components analogous to queen bee, drones, worker bees. The idea for

ZigBee started in the late 1990s, when many engineers realized that both Wi-Fi

and Bluetooth would be ill-suited to many applications. In particular, many

engineers wanted to design ad hoc networks of digital radios that could organize

themselves without requiring external configuration or network administration.

The IEEE 802.15.4 standard was completed in 2003 and ratified in late 2004.

The ZigBee Alliance formed in 2002, a rapidly growing internationalassociation of semiconductor companies, software providers, systems integrators,

and original equipment manufacturers (OEMs), is defining the ZigBee

specification, along with the requirements for certification , promote the ZigBee

standards and to provide product compliance testing. The goal of the ZigBee

Alliance is to provide "Wireless Control That Simply Works."

The ZigBee Alliance today comprises of more than 175 companies like Motorola,

LG, Intel, HP, Samsung, Phillips, Jennic, FreeScale, Invensys, Honeywell,

Chipcon, Arcom and many more.

By creating a standards-based wireless networking solution, the ZigBee Alliance

ensures that product solutions are vendor independent. Companies will be able to

easily and cost-effectively include ZigBee-compliant wireless networking


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4 Introduction

capabilities into their products through the introduction of small, low-power,

wireless RF modules. The availability of standards-based hardware and software

solutions dramatically reduces the cost and complexity of integrating embedded

RF into the typical product design.

1.4 Need ofZigbee

ZigBee was created to satisfy the markets need of a standards-based wireless

network that is 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 build a remote battery powered Bluetooth node, we need at least

250K of memory for the code and 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 thats targeted at

transmission speeds of 20-250KB/s, it has a transmission range of over 50

meters. Battery life is 2 years and 32K of system resources is required. This

is simple, effective, and very practical.

ZigBee is the only wireless standards-based technology that addresses the

unique needs ofremote monitoring control, and sensory networkapplications,

enables broad-based deployment

of wireless networks with low cost, lowpower solutions.

1.5 Wireless sensor networking is one ofthe most

exciting technology marketstoday

[4]. They say that over the next five to ten years, wireless sensors will have


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5 Introduction

a significant impact on almost all major industries as well as our home lives.

Broadly, this technology market 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 how they operate and what they do, their requirements from a

wireless communication technology are very similar. For example, these

applications generally require low data rates and are battery 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 project in an existing facility can be as high as 80project cost

2. Maintenance - It is easier to configure 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

unavailable to wired product.

Zigbee [3, 5] was introduced as an alternative to Bluetooth for

devices with low power consumption requirements and applications of lower

bit rates. Although products based on the Bluetooth standard are often

capable of operating at greater distances, the targeted operational area is

the one around an individual, (e.g. within a 10 meters diameter). Bluetooth

utilizes a short range radio link that operates in the 2.4 GHz industrial

scientific and medical (ISM) band similar to WLAN. However, the radio link

in Bluetooth is based on frequency hop spread spectrum. Although at any

point in time, the Bluetooth signal occupies only 1MHz, the signal changes

the center frequency (or hops) deterministically at a rate of 1600Hz.


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6 Introduction

Bluetooth hops over 79 center frequencies, so over time the Bluetooth signal

actually occupies 79MHz. The new short range, low power, low rate

wireless networking protocol, Zigbee, complements the high data rate

technologies such as WLAN and open the door for many new applications.

This standard operates at three bands, the 2.4 GHz band with a maximum

rate of 250 kbps, the 915 MHz band with adata rate of 40 kbps, and the 868

MHz band with a data rate of 20 kbps. While Bluetooth devices are better

suited for fairly high rate sensor and voice applications, Zigbee is better suited

for low rate sensors and devices used for control applications that do not

require high data rate but must have long battery life, low user interventions

and mobile topology. Some of these applications are in the fields of medicine

ZigBee is a low-cost, low-power, wireless mesh networking proprietary

standard. The low cost allows the technology to be widely deployed in

wireless control and monitoring applications, the low power-usage allows

longer life with smaller batteries, and the mesh networking provides high

reliability and larger range.

The ZigBee Alliance, the standards body that defines ZigBee,[1] also

publishes application profiles that allow multiple OEM vendors to create

interoperable products. The current list of application profiles either

published or in the works are: Home Automation ZigBee Smart Energy

1.0/2.0 Commercial Building Automation Telecommunication Applications

Personal, Home, and Hospital Care Toys.

The relationship between IEEE 802.15.4 and ZigBee is similar to that

between IEEE 802.11 and the Wi-Fi Alliance. The ZigBee 1.0 pecification


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7 Introduction

was ratified on 14 December 2004 and is available to members of the ZigBee

Alliance. Most recently, the ZigBee 2007 specification was posted on 30

October 2007. The first ZigBee Application Profile, Home Automation, was

announced 2 November 2007. As amended by NIST, the Smart Energy

Profile 2.0 specification will remove thedependency on IEEE 802.15.4. Device

manufacturers 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 in Europe, 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 as Bluetooth. ZigBee chip

vendors typically sell integrated radios and microcontrollers with between

60K and 128K flash memory, such as the Jennic JN5148, the Freescale

MC13213 the Ember EM250, the Texas Instruments CC2430, the Samsung

Electro-Mechanics ZBS240 and the Atmel ATmega128RFA1. Radios are

also available stand-alone to be used with any processor or microcontroller.

Generally, the chip vendors also offer the ZigBee software stack, although

independent ones are also available.

Because ZigBee can activate (go from sleep to active mode) in 15 msec or

less, the latency can be very low and devices can be very responsive

particularly compared to Bluetooth wake-up delays, which are typically

around three seconds. [2] Because ZigBee can sleep most of the time, average

power consumption can be very low, resulting in long battery life. The first

stack release is now called ZigBee 2004.

The second stack release is called ZigBee 2006, and mainly replaces the

MSG/KVP structure used in 2004 with a cluster library. The 2004 stack is


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8 Introduction

now more or less obsolete.[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 profile 2 (called ZigBee Pro).

ZigBee Pro offers more features, such as multi-casting, many-to-one routing

and high security with Symmetric-Key Key Exchange (SKKE), while ZigBee

(stack profile 1) offers a smaller footprint in RAM and flash. Both offer full

mesh networking and work with all ZigBee application profiles.[citation

needed] ZigBee 2007 is fully backward compatible with ZigBee 2006 devices:

A ZigBee 2007 device may join and operate on a ZigBee 2006 network and

vice versa. Due to differences in routing options, ZigBee Pro devices must

become non-routing ZigBee End-Devices (ZEDs) on a ZigBee 2006 or

ZigBee 2007 network, the same as ZigBee 2006 or ZigBee 2007 devices must

become ZEDs on a ZigBee Pro network. The applications running on those

devices work the same, regardless of the stack profile beneath them.

1.6 Uses

ZigBee protocols are intended for use in embedded applications requiring low

data rates and low power consumption. ZigBeescurrent focus is to define a

general-purpose, inexpensive, self-organizing mesh networkthat can be used

for industrial control, embedded sensing, medical data collection, smoke and

intruder warning, building automation, home automation, etc. The resulting

network will use very small amounts of power individual devices must have

a battery life of at least two years to pass ZigBee certification.

Typical application areas include Home Entertainment and Control

Smart lighting, advanced temperature control, safety and security, movies and

music Home Awareness Water sensors, power sensors, energy monitoring,


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9 Introduction

smoke and fire detectors, smart appliances and access sensors. Mobile Services

m-payment, m-monitoring and control, m-security and access control, m-

healthcare andtele-assist Commercial Building Energy monitoring, HVAC,

lighting, access controlIndustrial PlantProcess control, asset management,

environmental management, energy management, industrial device control.

1.7 Software and hardware

The software is designed to be easy to develop on small, inexpensivemicroprocessors. The radio design used by ZigBee has been carefully

optimized for low cost in large scale production. It has few analog stages and

uses digital circuits wherever possible.

Even though the radios themselves are inexpensive, the ZigBee

Qualification Process involves a full validation of the requirements of the

physical layer. This amount of concern about the Physical Layer has multiple

benefits, since all radios derived from that semiconductor mask set would

enjoy the same RF characteristics. On the other hand, an uncertified

physical layer that malfunctions could cripple the battery lifespan of other

devices on a ZigBee network. Where other protocols can mask poor sensitivity

or other esoteric problems in a fade compensation response, ZigBee radios

have very tight engineering constraints: they are both power and bandwidth

constrained. Thus, radios are tested to the ISO 17025 standard with guidance

given by Clause 6ofthe 802.15.4-2006 Standard. Most vendors plan to

integrate the radio and microcontroller onto a single chip.


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10 Protocol Stack

2.Protocolstack for Zigbee

Zigbee protocol stack mainly consists of PHY and MAC layer from IEEE

802.15.4 standard, Networklayer, Application layer.

Figure 2.1: Zigbee protocol stack

2.1 PHYSICAL layer

ZigBee operates in one of three license free bands 2.4 GHz, 915 MHz for North

America, and 868 MHz for Europe. At 2.4 GHZ, there are a total of 16 channels

available with a maximum data transfer of 250 kbps. At 915 MHz: 10

channels for a max 40 kbps transfer rate. At 868 MHz: 1 channel for a max

20 kbps transfer rate.


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11 Protocol Stack

2.1.1 Features ofPHY layer:

1. Activation and deactivation of the radio transceiver.

2. Energy detection- Here the power of received signal is estimated within

bandwidth of channel .It is used in network layer for channel selection.

3. Link quality indication (LQI)-This indicator shows the quality of the

link between devices 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 or empty. A mode in CCA performs the RF energy detection

with other wireless network is avoided.

5. Channel selection.

2.2 MAC layer

Mac layer control access to the radio channel. Its responsibilities are

transmitting beacon frames, synchronization 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 routesaround obstacles, 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 messages upstream or downstream. It can communicate with

the coordinator or a router, but not directly with other end devices.


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12 Protocol Stack

1. PAN coordinator:

Figure 2.2: Mac layer association

It is controller of a network that is responsible for the network formation

and maintenance. The PAN coordinator must be a router.

4. MAC Layer association

On the power on of end device it sends beacon request. Beacon is a


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13 Protocol Stack

transmission by a Zigbee router to confirm their presence o other

network devices.PAN coordinator sends the beacon. Then end device

requests for the association.PAN coordinator checks whether enough

resources are present or not if present it sends acknowledgement and

association is established between PAN coordinator and end device.

2.3 NetworkLayer

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 or empty. A mode in CCA performs the RF energy detection

with other wireless networkis 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


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14 Protocol Stack

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 and end. Each router is typically connected through at

least two pathways, and can relay messages for its neighbors. Mesh topology

supports multi-hop communications, through which data is passed by

hopping from device to device using the most reliable communication links

and most cost-effective path until its destination is reached. The multi-hop

ability also helps to provide fault tolerance, in that if one device fails or

experiences interference, the network can reroute itself using the remaining

devices.

2.4 Benefits ofMesh topology

1. This topology is highly reliable and robust. Should any individual router

become inaccessible, alternative routes can be discovered and used.

2. The use of intermediary devices in relaying data means that the range

of the network can be significantly increased, making this topology

highly scalable.

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


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15 Protocol Stack

routers to the network.

2.5 Limitations ofMesh topology

1. This topology has a higher communications overhead than the star

topology, which can result in increased latency and lower end-to-end

performance.

2. Meshed routing requires more complex network protocols. This means

the routers require more embedded resources, which can result in

increased power consumption and costs .

2.6 The power ofMesh Topology

Mesh networking was not created specifically for wireless sensor networks.

This network topology is already hard at work in both the public switched

telephone network (PSTN) and the Internet. The mesh is the best way to

achieve the resiliency and scalability demanded from these mission-critical

publicnetworks. Examining the key benefits that mesh topologies provide in a

bit more detail will help to explain why it is such an appropriate choice for

many 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) implement.

2.8 Star topology in Zigbee

In a Star topology, also called point-to-point, all devices are within direct

communication range to the coordinator, through which all messages are


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16 Protocol Stack

routed. A device sends a message to the coordinator, which then passes it on to

the destination device. Direct communication between the end devices is not

supported.

Figure 2.4: Star Topology

2.9 Benefits ofStar topology

1. Its simplicity means that this topology does not require a complex

network layer or routing protocols

2. Performance is generally high, with packets taking a maximum oftwo

hops to reach their destination.

2.10 Limitation ofStar topology1) 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 networkis limited by the radio range between the

coordinator and child devices (typically 30-100 meters).


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17 Protocol Stack

2.11 Application layer

Application layer mainly consists of Application support sublayer, Applic-

ation framework and Zigbee device objects

Application Support Sublayer- The portion of the Application Layer

responsible for providing a data service to the application and ZigBee device

profiles. In addition, it provides a 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 description of how to builda profile onto the ZigBee stack so that profiles can

be generated in a consistent manner. It also specifies a range of standard

data types for profiles, descriptors to assist in service discovery, frame

formats for transporting data, and a key value pair construct to rapidlydevelop simple, attribute based profiles.

Zigbee device objects-The portion of the ZigBee Application Layer

responsible for defining 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

betweennetwork devices. It also provides a rich set ofmanagement 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


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18 Protocol Stack

applications and competing requirements. Figure 1 shows an example of the

range of target markets typically discussed for ZigBee.

2.13 Security in Zigbee

ZigBee security, which is based on a 128-bit AES algorithm, adds to the

security model provided by IEEE 802.15.4. ZigBees security services include

methods for key establishment and transport, device management, and frame

protection. The ZigBee specification defines security for the MAC, NWK and

APS layers. Security for applications is typically provided through Application

Profiles.

2.13.1 Trust center

The Trust Center decides whether to allow or disallow new devices into its

network. The Trust Center may periodically update and switch to a newNetwork Key. It first broadcasts the new key encrypted with the old Network

Key. Later, it tells all devices to switch to the new key. The Trust Center is

usually the networkcoordinator, but is also able to be a dedicated device. It

is responsible for the following security roles:

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.


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19 Protocol Stack

Figure 2.5: Network

2.13.2 Securitykeys

ZigBee uses three types of keys to manage security: Master, Networkand

Link.

2.13.3 Master keys

These optional keys are not used to encrypt frames. Instead, they are used

as an initial shared 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 Trust Center Master Keys, while all other

keys are called Application Layer Master Keys.


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20 Protocol Stack

2.13.4 Networkkeys

These keys perform security Network Layer security on a ZigBee network.

All devices on a ZigBee networkshare the same key. High Security Network

Keys must always be sent encrypted over the air, while Standard Security

Network Keys can be sent either encrypted or unencrypted. Note that High

Security is supported only for ZigBee.

2.13.5 Link keys

These optional keys secure uncast messages between two devices at the

Application Layer. Keys that originate from the Trust Center are called Trust

Center Link Keys, while all other keys are called Application Layer Link

Keys.

2.14 Security modes

ZigBee offers twodifferent security modes: Standard and High.

2.14.1 Standard securitymode

In Standard Security mode, the list of devices, master keys, link keys and

network keys can be maintained by either the Trust Center or by the devices

themselves. The Trust Center is still responsible for maintaining astandard

network key and it controls policies of network admittance. In this mode,

the memoryrequirements for the Trust Center are far less than they are for

High Security mode.

2.14.2 High securitymode

In High Security mode, the Trust Center maintains a list of devices,

master keys, link keys and network keys that it needs to control and


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21 Protocol Stack

enforce the policies of network key updates and network admittance. As the

number of devices in the network grows, so too does the memory required

for the Trust Center.

The additional security capabilities inherent in ZigBee-pro are critical

as ZigBee is used in increasingly important applications. The control of

critical systems infrastructure, whether in a commercial building, utility

grid, industrial plant, or a home security system must not be compromised.

2.14.3 Difference between Zigbee and Bluetooth

Bluetooth and ZigBee have much in common. Both are types of IEEE

802.15 wireless personal-area networks, or WPANs. Both run in the 2.4-

GHz unlicensed frequency band, and both use small form factors and low .

Characteristics Bluetooth Zigbee

Range 10-100m 30-100m.Latency 10sec 30ms.Extendibility yes NoComplexity complex SimpleSecurity PIN 64bit,128bit 128bit AESBattery life Short Long

Table 2.1: Difference between Bluetooth and Zigbee


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22 Devices and Applications

3.Zigbee - Protocol, Devices andApplications

3.1 Protocol

The protocols are built on recent algorithmic research to construct a low-

speed ad-hoc network of nodes automatically. In large network instances,

the network will be a cluster of clusters in the form of a mesh or a single

cluster. ZigBee protocols minimize the time for which the radio is on to

reduce the power use. Thecurrent profiles derived from the ZigBee protocols

support beacon and non-beacon enabled networks.

In beacon enabled networks, the special network nodes called ZigBee

Routers transmit periodic beacons to confirm their presence to other

network nodes. Beacon Oriented networks use Guaranteed Time Slots

(GTS). Nodes are active only when a beacon is being transmitted. They

may sleep between beacons, that will lower the duty cycle and increase the

battery life. The intervals may range from 15.36 milliseconds to

3.2 What ZigBeesLowPowerConsumption Means

ZigBees low power consumption is rooted not in RF power, but in a sleep

mode specifically designed to accommodate battery powered devices. Any

ZigBee-compliant radio can switch automatically to sleep mode when its not

transmitting, and remain asleep until it needs to communicate again. For

radios connected to battery-powered devices, this results in extremely low

duty cycles and very low average power consumption.

When a radio is in sleep mode, its RF power rating is irrelevant; its only

when transmitting that its RF power affects power consumption. In the case

ofCirronets ZigBee solutions, a radio with 100 mW RF power will typically


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consume 150 mA at 3.3 V when transmitting, compared to 75 mA at 3.3 V for

a radio with 1 mW RF power. The 100 mW radio consumes twice as much

power - but only when actively transmitting. As long as the high power radios

low noise amplifier is turned off, power consumption while sleeping is roughly

equivalent to that of a low power radio.

If the high RF power radio is awake and transmitting 5very active radio, the

extra average power consumption is roughly 5power consumption means that

a battery that would last for five 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 candidates for use with

battery powered devices.

Its important to note that the ZigBee Alliance doesnt itself specify

anything for RF power. ZigBees RF power specification comes from IEEE

802.15.4, which specifies a minimum power output rating of 1 mW, with no

specified maximum. The defactor 100 mWhigh power level relates to the

European limit of 100 mW EIRP, including antenna gain.

3.3 Types

There are three differenttypes of ZigBee device:

1. ZigBee coordinator (ZC): The most capable device, the coordinator

forms the root of the network tree and might

bridge to other networks.There is exactly one ZigBee coordinator in each network. It is able to

store information about the network, including acting as the repository

for security keys.

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

passing data from other devices.

3. ZigBee End Device (ZED): Contains just enough functionality to talk


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to its parent node (either the coordinator or a router); it cannot relay

data from other devices.

3.4 Advantages

1. ZigBees main advantage is its ability to be configured in so-called mesh

networks with wireless 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 networktechnologies hence long battery life.

5. Low cost and Zigbee network designs are simple.

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

standard source.

3.5 Disadvantages

1. It works over short range.2. Data rate is low.

3.6 Modes of Operation

ZigBee operates in two main modes: non-beacon mode and beacon mode.

Beacon mode is a fully coordinated mode in that all the device know when to

coordinate with one another. In this mode, the network coordinator willperiodically "wake-up" and send out a beacon to the devices within its network.

This beacon subsequently wakes up each device, who must determine if it has any

message to receive. If not, the device returns to sleep, as will the network

coordinator, once its job is complete.

Non-beacon mode, on the other hand, is less coordinated, as any device can

communicate with the coordinator at will. However, this operation can cause


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different devices within the network to interfere with one another, and the

coordinator must always be awake to listen for signals, thus requiring more power.

In any case, ZigBee obtains its overall low power consumption because the

majority of network devices are able to remain inactive over long periods of time.

3.7 Applications ofZigbee

1. Home Automation-The ZigBee Home Automation profile is likely to be the

first ZigBee application profile to hit the marketplace in volume and also

holds promise to be the first application space where multiple products from

multiple vendors are truly interoperable allowing users to mix and match

products to enhance their digital lifestyle. Lighting control, thermostats,

occupancy and motion sensors, security systems, door and window sensors,

as well as fixed and mobile keypads all occupy the ZigBee home automation

space and can be bound together to make sophisticated home automation

behaviors.

2. Building automation-Wireless sensing and control mesh networks can make

building automation easier and more efficient by combining lighting, HVAC,

security, safety systems, and other monitoring networks into a single

platform.

3. Industrial plant monitoring-Wireless sensing and control mesh networks

provide accurate and efficient IPM, and are also ideal to deploy in hazardous

environments in which you want to minimize humanexposure.

4. PC and peripherals-PC and peripherals like mouse, keyboard, joystick can

be automated.

5. Personnel health care-Patientmonitoring, remote diagnosis are included in

personnel health care applications.


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3.8 Competent Technologies

ZigBee is not alone in the world of home automation and sensor networks.

It faces competition from technologies such as Z-Wave, a technology based on the

Zensys's Z-Wave open standard. This standard focuses on the same areas as

ZigBee and may actually control a bigger corner of the market. However, it lacks

a global standard and does not quite have the publicity that ZigBee currently

holds. Another existing automation technology is Insteon by Smarthome.

Insteon is very similar to ZigBee and Z-Wave technologies, except that it offers a

dual band network, as opposed to the single band networks of the latter two

technologies. Like ZigBee, Insteon has development kits available, while large

scale manufacturing is still on the not-to-distant horizon. Other proprietary mesh

protocols based on IEEE 802.15.4 ensure that ZigBee faces, and will continue to

face, a competitive market in the world of low rate networking.


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27 Conclusion

4.Conclusion

Comparing ZigBee technology with the other present technology it is evident

that ZigBee can have a safe future in this effervescent world of technology.

There is definitely a place on the market for ZigBee, since no global standard

exists today in the wireless sensor network area. ZigBee is the specification of

a low-cost, low-power wireless communications solution, meant to be

integrated as the main building block of ubiquitous networks. It is maintained

by the ZigBee 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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28 Bibliography

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[22]http://www.technologyreview.com/articles/zigbee

[23]http://www.zigbee.org

[24]http://www.wisegeek.com

[25]http://computing.arizona.edu

[26]http://en.wikipedia.org/wiki/ZigBee
http://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.technologyreview.com/articles/zigbeehttp://www.zigbee.org/http://www.zigbee.org/http://www.zigbee.org/http://www.zigbee.org/http://www.wisegeek.com/http://www.wisegeek.com/http://www.wisegeek.com/http://www.wisegeek.com/http://computing.arizona.edu/http://computing.arizona.edu/http://computing.arizona.edu/http://computing.arizona.edu/http://en.wikipedia.org/wiki/ZigBeehttp://en.wikipedia.org/wiki/ZigBeehttp://en.wikipedia.org/wiki/ZigBeehttp://en.wikipedia.org/wiki/ZigBeehttp://en.wikipedia.org/wiki/ZigBeehttp://en.wikipedia.org/wiki/ZigBeehttp://computing.arizona.edu/http://www.wisegeek.com/http://www.zigbee.org/http://www.technologyreview.com/articles/zigbee


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32 Glossary

GLOSSARY

AES : Advanced Encryption Standard

APS : Application Support Sublayer

CCA : Clear Channel Assessment

DLL : Data Link Layer

EIRP : Effective Isotropic Radiated Power

FFD : Full Function DeviceGTS : Guaranteed Time Slots

HVAC : Heating, Ventilation and Air-Conditioning

IPM : Industrial Plant Monitoring

IEEE : Institute of Electrical and Electronics Engineers

ISO : International Organization for Standardization

ISM : Industrial Scientific and Medical

IP : Internet Protocol

LQI : Link Quality Indication

MAC : Medium Access Control

MSG/ KVP : Message /Key-Value-Pair

NIST : National Institute of Standards and Technology

NWK : Network

OEM : Original Equipment Manufacturers

PHY : Physical

PSTN : Public Switched Telephone Network

RFD : Reduced Function Device
http://www.epa.gov/iaq/schooldesign/hvac.htmlhttp://www.epa.gov/iaq/schooldesign/hvac.html


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33 Glossary

RF : Radio Frequency

RAM : Random Access Memory

SKKE : Symmetric-Key Key Exchange

VCR : Video Cassette Recording

WI-FI : Wireless Fidelity, or Wireless Local Area Network, WLAN

WPAN : Wireless Personal Area Network

ZDP : Zigbee Device Profile

ZED : Zigbee End Device

ZR : Zigbee Router

ZC : Zigbee Co-ordinator


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b209013 seminar report 1

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