zigbee networks

8/8/2019 ZigBee Networks

1/51

ABSTRACT

Wireless connectivity ofavast number of industrial and home applications

has modest transmission data requirements, but demands reliable and secure

communication using simple low-cost and low-power radio systems. In the quest for high-

bandwidth, multimedia-capable wireless networks, the need for cost and power-effective

radio solutionsfor this vast number of fairlysimpleapplicationswas only recentlyaddressed

bya standardized technology.

The IEEE 802.15.4 standard and ZigBee wireless technology are designed tosatisfy the market's need for a low-cost, standard-based and flexible wireless network

technology,which offers low powerconsumption, reliability, interoperability and security for

controlandmonitoringapplications withlow tomoderate data rates.

The complexity and cost of the IEEE802.15.4/Zigbee-compliant devices are

intended to be low and scalable (application dependent) in order to enable broad

commercial adaptation in cost-sensitive applications. In addition, the compliant system

implementations will enable long battery life by using the power-saving featuresat the

physical, MACandnetwork layers specified by thisstandard.

In this respect, the implementation of the physical layer of the IEEE 802.15.4

standard, including the RF, IF and de-modulation must be optimized to meet the

challenginglow-cost and low-powertargets.

Seminar Re ort 06-07 1 Zi Bee Networks

Department of Electronics & Communication Vimal Jyothi Engineering College


2/51

TABLE OF CONTENTS

CHAPTER1: INTRODUCTI ON 06

1.1 EVOLUTION OF LR-WPAN STANDARDIZATION 06

1.2 ZigBeeAND IEEE 802.15.4 07

1.3 WHY IS ZigBee NEEDED 08

1.4 ZigBeeAND BLUETOOTH 09

1.5 WIRELESSTECHNOLOGY COMPARISON CHART 10

CHAPTER 2: ZIGBEE /IEEE 802.15. 4 WPAN 12

2.1 COMPONENTS OFWPAN 12

2.2 NETWORK TOPOLOGIES 12

2.2.1 STARTOPOLOGY 12

2.2.2 PE ER-TO-PEERTOPOLOGY 13

2.2.3 CLUSTER-TREE TOPOLOGY 14

2.3 ZIGBEE ARCHITECTURE 15

CHAPTER3: IEEE 802.15. 4 PHY 17

3.1 RECEIVER ENERGY DETECTION (ED) 19

3.2LINK QUALITY INDICATION(LQI) 19

3.3CLEAR CHANNEL ASSESSMENT(CCA) 20

3.4 PPDU FORMAT 20

CHAPTER 4: IEEE 802.15. 4MAC 22

4.1 FRAME STRUCTURE 22

4.2 CHANNELACCESS AND ADDRESSING 23

4.3SUPER FRAME STRUCTURE 24

4.4 CSMA-CA ALGORITHM 25

4.5 DATA TRANSFERMODEL 26

4.6 MAC LAYER SECURITY 28




3/51

TABLE OF CONTENTS(2)

CHAPTER5: NERWORK LAYER 31

5.1 ZIGBEE NETWORKNODE 32

5.2 RESPONSIBILITIES OFTHE ZIGBEENWK LAYER 32

5.3 NETWORK LAYER SECURITY 33

CHAPTER6: ZIGBEEROUTING MECHANISM 35

6.1AODV: AD HOCON DEMAND DISTANCE VECTOR 35

6.2 CLUSTER-TREEALGORITHM 38

6.2.1 SINGL E CLUSTER NETWORK 38

6.2.2 MULTI-CLUSTER NETWORK 41

CHAPTER7: APPLICATION LAYER 46

7.1 APPLICATION SUPPORT LAYER 46

7.2 THEGENERAL OPERATION FRAMEWORK(GOF) 46

7.3 ZIGBEE DEVICE 47

7.4 ZIGBEE DEVICEOBJECTS 47

CHAPTER8:ZIGBEE - APPLICATIONS 48

8.1 PRODUCT EXAMPLES 49

8.2 HOME& DIAGNOSTICS EXAMPLES 49

ZIGBEE:CONCLUSION 50

ZIGBEE: BIBLIOGRAP HY 51




4/51

ZigBee

CHAPTER 1

INTRODUCTION




5/51

INTRODUCTION 1

1.1Evolution of LR-WPAN StandardizationThe cellular network was a natural extension of the wired telephony network that

became pervasive during the mid-20th century. As the need for mobility and the

cost of laying new wires increased, the motivation for a personal connection

independent of location to that network also increased. Coverage of large area is

provided through (1-2km) cells that cooperate with their neighbors to create a

seemingly seamless network. Examplesofstandards areGSM, IS-136, IS-95. Cellular

standards basicallyaimedat facilitating voice communicationsthroughouta metropolitan

area.

During the mid-1980s, it turned out thatan even smallercoveragearea is needed for

higher user densities and the emergent data traffic. The IEEE 802.11 working group

for WLANsisformedto create a wireless localarea network standard.

Whereas IEEE 802.11 was concerned with features such as Ethernet matching

speed, long-range(100m), complexity to handle seamless roaming, message

forwarding, and data throughput of 2-11Mbps, WPANs are focused on a space

around a person or object that typically extends up to 10m in all directions. Thefocus of WPANs is low-cost, low power, short range and very small size. The

IEEE802.15 working group is formed to create WPAN standard. This group has

currently defined three classes of WPANs that are differentiated by data rate, battery

drain and quality of service (QoS). The high data rate WPAN (IEEE 802.15.3) is

suitable formulti-media applications that requirevery high QoS.Medium rateWPANs

(IEEE802.15.1/Blueetooth) will handle a variety of tasks ranging from cell phones to

PDA communications and haveQoSsuitableforvoice communications. The low rate

WPANs (IEEE 802.15.4/LR-WPAN) is intended to serve a set of industrial,residential and medical applications with very low power consumption and cost

requirement notconsidered by the above WPANs and with relaxed needs for data rate

and QoS. The low data rate enables the LR-WPAN to consume very little power.




6/51

1.2 ZigBee and IEEE 802.15.4

ZigBee technology is a low data rate, low power consumption, low cost; wireless

networking protocol targeted towards automation and remote control applications.

IEEE 802.15.4 committee started working on a low data rate standard a short while

later. Then the ZigBee Alliance and the IEEE decided to join forces and ZigBee is the

commercialnamefor this technology.

ZigBee is expected toprovide lowcostand low power connectivity for equipment that

needs battery life as long as several months to several years but does not require

data transfer rates as high as those enabled by Bluetooth. In addition, ZigBee

can be implemented in mesh networks larger than is possible with Bluetooth.

ZigBee compliant wireless devices are expected to transmit 10-75 meters,

depending on the RF environment and the power output consumption required for

a given application, and will operate in the unlicensed RF worldwide (2.4GHzglobal,

915MHz in USA OR868MHz in Europe). Thedata rate is 250kbps at2.4GHz, 40kbps

at915MHz and 20kbps at868MHz.

IEEE and ZigBee Alliance have been working closely to specify the entire protocol

stack. IEEE 802.15.4 focuses on the specification of the lower two layers o f the

protocol (physical and data link layer). On the other hand, ZigBee Alliance aims to

provide theupper layers ofthe protocol stack(fromnetwork totheapplication layer) forinteroperable data networking, security services and a range of wireless home and

building control solutions, provide interoperability compliance testing, marketing of the

standard, advanced engineering for the evolution of the standard. This will assure

consumers to buy products from different manufacturers with confidence that the

products will work together.

IEEE 802.15.4 is now detailing the specification of PHY and MAC by offering

building blocks for different types of networking known as star, mesh, and cluster

tree. Networkrouting schemesare designed to ensurepower conservation, and lowlatency through guaranteed time slots. A unique feature ofZigBee network layer iscommunication redundancy eliminating single point of failure in mesh networks.

Key features of PHY include energy and link quality detection, clear channel

assessmentforimproved coexistencewith other wirelessnetworks.




7/51

1.3 Why is ZigBee Needed?

There are a multitude of standards like Bluetooth and WiFi that address mid to high

data rates for voice, PC LANs, video, etc. However, up till now there hasn't been awireless network standard that meets the unique needs of sensors a n d control

devices. Sensors and controls don't need high bandwidth but they do need low

latency and very low energy consumption for long battery lives and for large device

arrays.

There are a multitude of proprietary wireless systems manufactured today to solve a

multitude of problems that don't require high data rates but do require low cost and

very low current drain. These proprietary systems were designed because there

were no standards that met theirapplication requirements. These legacy systems

are creating significant interoperability problems with each other and with newer

technologies.

ZigBeeis poisedto become the global control/sensor networkstandard. It hasbeen

designed to provide the following features:

Low powerconsumption, simply implemented

Users expect batteries to last many months to years!Consider thata typical

single family house has about 6 smoke/CO detectors. If the batteries for

each one only lasted six months, the home owner would be replacing

batteriesevery month!

In contrast to Bluetooth, which has many different modes and states

depending upon your latency and power requirements, ZigBee/IEEE

802.15.4 has two major states: active (transmit/receive) or sleep. The

applicationsoftware needs to focus on theapplication, not onwhich power

mode is optimumforeachaspect of operation.

Even mains powered equipment needs to be conscious of energy. ZigBee

devices will be more ecological than their predecessors saving megawattsat it

full deployment. Consider a future home that has 100 wirelesscontrol/sensor devices,

o Case 1: 802.11 Rx power is 667 mW (always on)@ 100

Devices/home & 50,000homes/city=3.33 megawatts

o Case 2: 802.15.4 Rx power is 30 mW (always on)@ 100

Devices/home & 50,000homes/city=150 kilowatts




8/51

o Case3: 802.15.4 powercycled at.1% (typicaldutycycle) = 150 watts

Low cost to the users means lowdevicecost, low installationcost and low

maintenance.

o ZigBeedevices allow batteriesto lastup to years using primary cells

(low cost) without any chargers (low cost and easy installation).

ZigBee's simplicity allows for inherent configuration and redundancy of

networkdevices provides lowmaintenance.

Highdensity of nodes per network

o ZigBee's use of the IEEE 802.15.4 PHY and MAC allows networks to

handle any number of devices. This attribute is critical for massive

sensor arrays and control networks.

Simple protocol,global implementation

o ZigBee's protocol code stack is estimated to be about 1/4th of

Bluetooth's or 802.11's. Simplicityis essentialto cost, interoperability, and

maintenance. The IEEE 802.15.4 PHY adopted by ZigBee has been

designed for the 868 MHz band in Europe, the 915 MHz band in N

America, Australia,etc;and the 2.4 GHzband is nowrecognized to be a

global bandaccepted in almost allcountries.

1.4 ZigBee vs. Bluetooth ZigBee looks rather like Bluetooth but is simpler, has a lower data rate and

spends most of its time snoozing. This characteristic means that a node on a

ZigBee network should be able to runfor six months totwoyears onjusttwo AA

batteries.

The operational range of ZigBee is 10-75m compared to10m for Bluetooth

(without a poweramplifier).

ZigBeesits belowBluetooth in termsof data rate.

Thedata rate ofZigBee is

250kbpsat 2.4GHz, 40kbpsat 915MHz and 20kbpsat 868MHzwhereas that of

Bluetoothis 1Mbps.

ZigBee uses a basic master-slave configurationsuitedto static star networks of

many infrequently used devices that talkvia small data packets. It allows up to

254 nodes. Bluetooths protocol is more complex since it is geared towards




9/51

handling voice, images and file transfers in ad hoc networks. Bluetooth

devices can support scatter nets of multiple smaller non-

synchronizednetworks(piconets). Itonly allows upto 8 slave nodes in a basic

master-slave piconetset-up.

When ZigBee node ispowereddown, it can wake up and get a packet in

around15msecwhereas a Bluetooth device would takearound3sec towake up

and respond.

ZigBee and Bluetooth are twosolutions for two different application areas.

Bluetooth has addressed a voice application by embodying a fast frequency

hopping system with a master slave protocol. ZigBee has addressed

sensors, controls, and other short message applications by embodying a

direct sequence system with a star or peer to peer protocols.

1.5 Wireless technology comparison chart

Wi-Fi Bluetooth WiMAX WiMedia ZigBee

Primary

Use

Laptopnetworking

Cable replacement,cellphones

Wireless broadbandInternet access

Multimedia consumerelectronics

Sensor networks,industrial control

LAN type WLAN WPAN WMAN WPAN WPAN

IEEE 802.11n 802.15.1 802.16 802.15.3 802.15.4

Standards Wi-Fi Alliance Bluetooth SIG WiMAX Forum WiMedia Alliance ZigBee Alliance

URL wi-fi.org bluetooth.org wimaxforum.org wimedia.org zigbee.org

Range(m) 100m 10-100m 50km 4-10m 30-70m

Bands 2.4 GHz 2.4 GHz 2.5 GHz, 3.5 GHz 3.1-10.6 GHz2.4 GHz, 866/900

MHz

DataSpeeds 11-54 Mbps 1 Mbps 280 Mbps 110-480 Mbps 20-250Kbps

BOM (US$) 9 6 150 20 3

Battery Life Hours Days N/A Days-weeks Months-years




10/51

ZigBee

CHAPTER 2

ZigBee / IEEE 802.15.4 WPLAN

2.0 ZigBee / IEEE 802.15.4 WPAN




11/51

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

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

inexpensive fixed, portable and moving devices. It is developed for applications with

relaxed throughput requirements which cannot handle the power consumption ofheavy protocolstacks.

2.1 Components of WPAN

A ZigBee system consists of several components. The most basic is the device. A

device can be a full-function device (FFD) or reduced-function device (RFD). A

network shall include at least one FFD, operatingas the PANcoordinator.

The FFD can operate in three modes: a personal area network (PAN) coordinator, a

coordinator or a device. An RFD is intended for applications that are extremely

simple and do not need to send large amounts of data. An FFDcan talk to RFDs or

FFDs while anRFD canonlytalk to an FFD.

2.2 Network Topologies

ZigBee supports 3 types of topologies - star topology, peer-to-peer topology and

cluster tree topology.

2.2.1 Star Topology

In the star topology, the communication is established between devices and a

single central controller, called the PAN coordinator. The PAN coordinator may be

mains poweredwhile the deviceswill most likely be batterypowered.Applications that

benefit from this topology include home automation, personal computer (PC)

peripherals, toysand games.

After an FFD is activated for the first time, it may establish its own network and

become the PANcoordinator. Eachstart networkchooses a PAN identifier, whichis not

currently used by any other network within the radio sphere of influence. This allows

each star networktooperate independently.

2.2.2 Peer-to-peer Topology

In peer-to-peer topology, there is also one PAN coordinator. In contrast to star

topology, anydevicecan communicate with anyother device as long as they

are in range of one another. A peer-to-peer network can be ad hoc, self-organizing




12/51

and self-healing.Applications such as industrial controland monitoring, wireless sensor

networks, asset and inventory tracking would benefit from such a topology. It also

allows multiple hops to route messages from any device to any other device in the

network.It can provide reliability by multi path routing.

2.2.3 Cluster-tree Topology




13/51

Cluster-tree network is a special case of a peer-to-peer network in which most

devices are FFDs and an RFD may connect to a cluster-tree network as a leave

node at the end of a branch. Any of the FFD can act as a coordinator and provide

synchronization services to other devices and coordinators. Only one of these

coordinators however is thePANcoordinator.

The PANcoordinatorformsthefirstcluster by establishing itself as theclusterhead

(CLH) with a cluster identifier (CID) of zero, choosing an unused PAN identifier, and

broadcasting beacon frames to neighboring devices. A candidate device receiving a

beacon frame may request to join the network at the CLH. If the PAN coordinator

permits thedevice to join, it will add this new deviceas a child device in its neighbor list.

The newly joined device will add the CLH as its parent in its neighbor list and begin

transmitting periodic beacons such that other candidate devices may then join the

network at that device. Once application or network requirements are met, the PAN

coordinator may instruct a device to become the CLH of a new cluster adjacent to

the first one.Theadvantageof this clustered structure is the increased coverage area

atthe cost of increasedmessage latency.

2.3 ZigBee Architecture




14/51

ZigBee architecture comprises a PHY, which contains the radio frequency (RF)

transceiver along with its low-level control mechanism, and a MAC sublayer that

provides access to the physical channel for all types of transfer. The upper layers

consists of a network layer, which provides network configuration, manipulation, and

message routing, and application layer, which provides the intended function of a

device. An IEEE 802.2 logical link control (LLC) can access the MAC sublayer

through the service specific convergence sublayer (SSCS). Chapter 3 describes the

physical layerofIEEE802.15.4. Chapter4explainstheMAC layerof IEEE 802.15.4.

Chapter 6 gives the routing mechanisms that aregoingto be used in the ZigBee.




15/51

ZigBee

CHAPTER 3

PHYSICAL LAYER

PHYSICAL LAYER 3




16/51

3.0 IEEE 802.15.4 PHY

The PHY provides two services: the PHY data service and PHY management

service interfacing to the physical layer management entity (PLME). The PHY data

service enables the transmission and reception of PHY protocol data units (PPDU)

across thephysicalradio channel.

The features of the PHY are activation and deactivation of the radio transceiver,

energy detection (ED), link quality indication (LQI), channel selection, clear channel

assessment (CCA) and transmitting as well as receiving packets across the

physical medium.

The standardofferstwo PHY optionsbased onthefrequency band. Bothare based on

direct sequence spread spectrum(DSSS). The data rate is250kbpsat 2.4GHz, 40kbps

at 915MHz and 20kbps at 868MHz. The higher data rate at 2.4GHz is attributed to

a higher-order modulation scheme. Lower frequencies provide longer range due to

lower propagation losses. Low rate can be translated into better sensitivity and

larger coverage area. Higher rate means higher throughput, lower latency or lower

duty cycle. This informationis summarized inthe table below.

There is asingle channel between868and868.6MHz, 10 channels between902.0

and 928.0MHz, and 16channels between 2.4 and 2.4835GHz as shown in




17/51

Figure 3.2.

Several channels in different frequency bands enables the ability to relocate within

spectrum. The standard also allows dynamic channel selection, a scan function

that steps through a list of supported channels in search of beacon, receiver

energydetection, link qualityindication, channel switching.

Receiver sensitivities are -85dBm for 2.4GHz and -92dBm for 868/915MHz. The

advantageof 6-8dB comes from the advantageof lower rate.The achievable range isa function of receiversensitivity and transmits power.The maximum transmit power shall conform with local regulations. A compliant

device shall have its nominal transmit power level indicated by the PHY parameter,

phyTransmitPower.

Figure 3.2: Operating frequency bands.

3.1 Receiver Energy Detection (ED)

Channels 11-26 5 MHz2.4 GHzPHY



868MHz / 915MHz

PHY868.3 MHz

Channel 0 Channels 1-10

928 MHz902 MHz

2 MHz


18/51

The receiver energy detection (ED) measurement is intended for use by a network

layer as part of channel selection algorithm. It is an estimate of the received signal

power within the bandwidth of an IEEE 802.15.4 channel. No attempt is made to

identify or decode signals on thechannel. TheED time should be equal to 8 symbol

periods.

The ED result shall be reported as an 8-bit integer ranging from 0x00 to 0xff. The

minimum ED value (0) shall indicate received power less than 10dB above the

specified receiver sensitivity. The range of received power spanned by the ED

values shall be at least 40dB. Within this range, the mapping from the received

power in decibelstoED values shall be linear with an accuracyof+ - 6dB.

3.2 Link Quality Indication (LQI)

Upon reception of a packet, the PHY sends the PSDU length, PSDU itself and link

quality (LQ) in the PD-DATA. indication primitive. The LQI measurement is a

characterization of the strength and/or quality of a received packet. The

measurement maybe implemented using receiver ED, asignal-to-noise estimation ora

combination of these methods. The use of LQI result is up to the network or

application layers.

The LQI result should be reported as an integer ranging from 0x00 to 0xff. The

minimum and maximum LQI values should be associated with the lowest and

highest quality IEEE 802.15.4 signals detectable by the receiver and LQ values

should be uniformlydistributedbetweenthese two limits.

3.3 Clear Channel Assessment (CCA)




19/51

The clear channelassessment (CCA) isperformed according to atleastone of the

following three methods:

Energy above threshold. CCA shall report a busy medium upon detecting any

energy abovethe ED threshold.

Carrier sense only. CCA shall report a busy medium only upon the detection of a

signal with the modulation and spreading characteristics of IEEE 802.15.4. This

signal maybe aboveor belowthe EDthreshold.

Carrier sense with energy above threshold. CCA shall report a busy medium only

upon the detection of a signal with the modulation and spreading characteristics of

IEEE 802.15.4 withenergy abovethe ED threshold.

3.4 PPDU Format

The PPDUpacket structure isillustrated inFigure 3.3.Each PPDU packetconsists of

thefollowing basiccomponents:

SHR,which allowsa receiving device tosynchronize and lock into thebit stream

PHR,which containsframe lengthinformation

Avariable lengthpayload,which carries theMAC sublayerframe.

Figure 3.3: Format of thePPDU.




20/51

ZigBee

CHAPTER 4

MEDIA ACCESS CONTROL LAYER




21/51

MAC LAYER 4

4.0 IEEE 802.15.4 MAC

The MAC (Media access control) layer sub layer provides two services: the MAC

data service and the MAC management service interfacing to the MAC sub layer

management entity (MLME) service access point (SAP) (MLMESAP). The MAC

data service enables the transmission and reception of MAC protocol data units

(MPDU) acrossthe PHYdata service.

The features of MAC sub layer are beacon management, channel access, GTS

management, frame validation, acknowledged frame delivery, association and

disassociation.

4.1 Frame Structure

The frame structures have been designed to keep the complexity to a minimum

while at the same time making them sufficiently robust for transmission on a noisy

channel. Each successive protocol layer adds to the structure with layer-specific

headers and footers.

The IEEE802.15.4 MACdefines four frame structures A beaconframe, usedby a coordinator totransmit beacons.

Adata frame, used for all transfersofdata. An acknowledgment frame, usedfor confirming successful frame reception.

A MAC command frame, used for handling all MACpeer entity control

transfers.

Thedataframe is illustrated below:




22/51

ThePhysical Protocol DataUnit isthe totalinformationsentoverthe air. As shown

in the illustrationabove the Physical layeradds thefollowing overhead:

Preamble Sequence 4 Octets Start of Frame Delimiter 1 Octet

Frame Length 1 Octet TheMAC addsthe following overhead:

Frame Control 2 Octets Data Sequence Number 1 Octet

Address Information 4 20 Octets Frame Check Sequence 2

Octets

In summary the total overhead for a single packet is therefore 15 -31 octets (120

bits); depending upon the addressing scheme used (short or 64 bit addresses).

Please notethatthese numbersdonot include any security overhead.

4.2Channel access and Addressing

Two channel-access mechanisms are implemented in 802.15.4. For a non-

beacon network,a standard ALOHA CSMA-CA (carrier-sense medium-accesswith

collision avoidance) communicates with positive acknowledgement for successfully

received packets. In abeacon-enabled network, a superframe structure is used to

control channel access. The superframe is set up by the network coordinator to

transmit beaconsat predetermined intervals (multiples of 15.38ms, up to252s)and

provides16 equal-width time slots between beacons for contention-free channel access in

each time slot. The structure guarantees dedicated bandwidth and low latency.

Channel access in each time slot is contention-based. However, the network

coordinator candedicateup to sevenguaranteed time slots perbeacon interval for

quality of service.

Device addresses employ 64-bit IEEE and optional 16-bit short addressing. The

address field within the MAC can contain both source and destination address

information (needed for peer-to-peer operation). This dual address information isusedin mesh networks to prevent asingle point of failurewithin the network.

4.3 Super Frame Structure

The LR-WPAN standard allows the optional use of a superframe structure. The

format of the superframe isdefinedby the coordinator. Thesuperframe isbounded by

network beacons,issent by the coordinator (SeeFigure4) and is divided into16 equally

sized slots. The beacon frame is transmitted in the first slot of each superframe.




23/51

If a coordinatordoesnot wish touse a superframe structureit mayturn off the beacon

transmissions. The beacons are used to synchronize the attached devices, to identify

the PAN, and to describe the structure of the superframes. Any device wishing to

communicate during thecontentionaccessperiod(CAP) between two beacons shall

compete with other devices using a slotted CSMA-CA mechanism. All

transactions shall be completed by the time of the next network beacon.

Figure 4.1

For low latency applications or applications requiring specific data bandwidth, the

PAN coordinator may dedicate portions of the active superframe to that application.These portions are called guaranteed time slots (GTSs). The guaranteed time slots

comprise the contention free period (CFP), which always appears at the end of the

active superframe starting at a slot boundary immediately following the CAP, as

shown in Figure5. ThePAN coordinator mayallocateup to seven of these GTSs and

a GTS may occupy morethan one slot period. However, a sufficient portion of the CAP

shall remain for contention based access of other networked devices or newdevices

wishing to join the network. All contentionbased transactions shall be complete before

the CFP begins. Also each device transmitting in a GTS shall ensure that its

transaction iscompletebefore the timeof thenext GTS or the end of the CFP.

Figure 4.2

4.4 CSMA-CA AlgorithmIf superframe structure is used in the PAN, then slotted CSMA-CA shall be used. If

beacons are not being used in the PANorabeacon cannotbe located in abeacon-

enabled network, unslotted CSMA-CA algorithm is used. In both cases, the

algorithm is implemented using units of time called backoff periods, which is equal to

aUnitBackoffPeriodsymbols.In slotted CSMA-CA channel access mechanism, the backoff period boundaries of

every device in the PAN are aligned with the superframe slot boundaries of the




24/51

PAN coordinator. In slotted CSMA-CA, each time a device wishes to transmit data

frames during the CAP, it shall locate the boundary of the next backoff period. In

unslotted CSMA-CA, the backoff periods of one device do not need to be

synchronizedto thebackoff periods of another device.

Each device has 3 variables: NB, CW and BE. NB is the number of times the

CSMA-CA algorithm was required to backoff while attempting the current

transmission. It is initialized to 0 before every new transmission. CW is the

contention window length, whichdefinesthenumber ofbackoff periods thatneed to be

clear of activity before the transmission can start. It is initialized to 2 before each

transmission attempt and reset to 2 each time thechannel is assessed to bebusy. CW

isonlyused forslotted CSMA-CA.BE is the backoffexponent, which is related to how

many backoff periods a device shall wait before attempting to assess the channel.

Although the receiver of the device is enabled during the channel assessment

portion of this algorithm, thedevice shalldiscard any frames received during thistime.

In slotted CSMA-CA, NB, CW and BE are initialized and the boundary of the next

backoffperiod islocated.In unslotted CSMA-CA, NBand BE are initialized(step1). The

MAC layershall delayfora randomnumberof completebackoff periods in the range 0

to 2BE - 1 (step2) then request thatPHY performs a CCA (clear channel assessment)

(step 3). The MAC sublayer shall then proceed if the remaining CSMA-CA

algorithm steps, the frame transmission, and anyacknowledgement can be completedbefore the end of the CAP. If the MAC sublayer cannot proceed, it shall wait until

the start of the CAP in the next

superframe and repeat the evaluation.

If the channel is assessed to be busy (step 4), the MAC sublayer shall increment

both NB and BE by one, ensuring that BE shall beno more thanaMaxBE. In slotted

CSMA-CA, CWcan also be reset to 2. If the value of NB is less than or equal to

macMaxCSMABackoffs, the CSMA-CA shall return to step 2, else the CSMA-CA

shall terminate with a ChannelAccess Failure status.

If the channel is assessed to be idle (step 5), in a slotted CSMA-CA, the MAC

sublayer shall ensure that contention window is expired before starting

transmission. For this, the MAC sublayer first decrements CW by one. If CW is not

equal to 0, go to step 3 else start transmission on the boundary of the next backoff

period. In the unslotted CSMA-CA,the MAC sublayer start transmission immediately if

the channel isassessed to beidle.




25/51

4.5 Data Transfer model

Three types ofdata transfer transactionsexist: from a coordinator toa device, from a

device to a coordinator and between two peer devices. The mechanism for each of

these transfers depend on whether the network supports the transmission ofbeacons. When a device wishes to transfer data in a nonbeacon-enabled network, it

simply transmitsits data frame, using the unslottedCSMA-CA,to thecoordinator. There

isalso an optional acknowledgement at theendas shown in Figure4.3.

Figure 4.3: Communi cation to a coordinator in abeacon-enabled network.

When a device wishes to transfer data to a coordinator in a beacon-enabled

network, it first listens for the network beacon. When the beacon is found, it

synchronizes to the superframe structure. At the right time, it transmits its data

frame, using slotted CSMA-CA, to the coordinator. There is an optional

acknowledgement at the endas shownin Figure 4.4.

Figure 4.4: Communicat ion to a coordinator in a non beacon-enabled n etwork.

The applications transfers are completely controlled by the devices on a PAN rather

than by the coordinator. This provides the energy-conservation feature of the

ZigBee network. When a coordinator wishes to transfer data to a device in a

beacon-enabled network, it indicates in the network beacon that the data message is

pending. The deviceperiodically listens to the network beacon, and if a message ispending, transmits a MAC command requesting this data, using slotted CSMA- CA.




26/51

The coordinator optionally acknowledges the successful transmission of this packet.

The pending data frame is then sent using slotted CSMA-CA. The device

acknowledged the successful reception of the data by transmitting an

acknowledgement frame. Upon receiving the acknowledgement, the message isremoved from thelist ofpending messages in thebeaconas shown in Figure4.5.

Figure 4.5: Communicat ion fromacoordinator in a be acon-enabled network.

When a coordinator wishes to transfer data to a device in a nonbeacon-enabled

network, it stores the data for the appropriate device to make contact and request

data. A device may make contact by transmitting a MAC command requesting the

data, using unslotted CSMA-CA, to its coordinator at an application-defined rate.

The coordinator acknowledges this packet. If data are pending, the coordinator

transmits the data frame using unslotted CSMA-CA. If data are not pending, thecoordinator transmits a data frame with a zero-length payload to indicate that no

data were pending.The device acknowledges this packet asshown in Figure4.6.

Figure 4.6: Communi cation from a coordinator in a non beacon-enabled network.

In a peer-to-peer network, every device can communicate with any other device in its

transmission radius. Thereare two optionsforthis.In thefirst case, the nodewill listen

constantly and transmit its data using unslotted CSMA-CA. In the second case, the

nodessynchronize witheachotherso that they can savepower




27/51

4.6 MAC Layer Security

When security of MAC layer frames is desired, ZigBee uses MAC layer security tosecure MAC command, beacon, and acknowledgement frames. ZigBee may secure

messages transmitted over a single hop using secured MAC data frames, but for

multi-hop messaging ZigBee relies upon upper layers (such as the NWK layer)for

security. The MAC layer uses the Advanced Encryption Standard (AES) as its core

cryptographic algorithm and describes a variety of security suites that use the AES

algorithm. These suites can protect the confidentiality, integrity, and authenticity of

MAC frames. The MAC layer does the security processing, but the upper layers,

which set up the keys and determine the security levels to use, control this

processing. When the MAC

layer transmits (receives) a frame with security enabled, it looks at the destination

(source)of theframe, retrieves the key associated with that destination (source), and

then uses this key to process the frame according to the security suite designated for

the key being used. Eachkeyis associated with a single security suite and the MAC

frame header has a bit that specifies whether security for a frame is enabled or

disabled.

When transmitting a frame, if integrity is required, the MAC header and payload

data are used in calculations to create a Message Integrity Code (MIC) consisting of

4, 8, or 16 octets. The MIC is right appended to the MAC payload. If

confidentiality is required,the MAC framepayload isalso left appended with frame and

sequence counts (data used to form a nonce). The nonce is used when

encrypting the payload and also ensures freshness to prevent replay attacks. Upon

receiptof a frame, if aMIC is present, itisverifiedand if the payload is encrypted,it is

decrypted. Sending devices will increase the frame count with every message sentand receiving devices will keep track of the last received count from each sending

device. If a message with an old count is detected, it is flagged with a security

error. The MAC layer security suites are based on three modes of operation.

Encryptionat the MAC layer isdoneusing AES in Counter (CTR) mode and integrityis

done using AES in C ipher Block Chaining (CBC- MAC) mode [16]. A combination of

encryption and integrity isdone usingamixtureof CTR and CBC- MAC modes called

the CCM mode.




28/51

ZigBee

CHAPTER 5

NETWORK LAYER




29/51

NETWORK LAYER 5

5.0 NWK LAYER

The NWK layer associates or dissociates devices using the network coordinator,

implements security, and routes frames to their intended destination. In addition,

the NWK layer of the networkcoordinator is responsible for starting anewnetwork and

assigning an address to newly associated devices.

The NWK layer supports multiple network topologies including star, cluster tree,

and mesh, all ofwhich are shown in Figure5.1

Figure 5.1: Network topologies

In a star topology, one of the FFD-type devices assumes the role of network

coordinator and is responsible for initiating and maintaining the devices on the

network. All other devices, known as end devices, directly communicate with the

coordinator.

Inamesh topology, theZigBee coordinator is responsible for starting the network and

for choosing key network parameters, but the network may be extended through

the use of ZigBee routers. The routing algorithm uses a request-response protocol to

eliminate sub-optimal routing. Ultimate network size can reach 264 nodes (more than

ZigBee End Device (RFD or FFD)

ZigBee Router (FFD)

ZigBee Coordinator (FFD)

Mesh Link




30/51

we'll probablyneed).Using local

addressing,you can configure simple networks of more than 65,000 (216

) nodes,

thereby reducing address overhead.

5.1 ZigBee Network Node

Designed for battery poweredor high energy savings

Searches for available networks

Transfers data from its applicationasnecessary

Determines whether datais pending

Requests datafromthe network coordinator Cansleep for extended periods

5.2 Responsibilities of the ZigBee NWK layer

Starting a network: The ability tosuccessfullyestablishanewnetwork.

Joining and leavinganetwork: The abilityto gainmembership (join) or relinquish

membership (leave) anetwork.

Configuring anewdevice: The abilityto sufficiently configure the stack for

operation asrequired.

Addressing: Theability of a ZigBee coordinator toassign addresses to devices

joining the network.

Synchronizationwithin a network: Theabilityfor a deviceto achieve

synchronizationwith another device either through tracking beacons orby

polling.

Security: applying security to outgoingframes and removing security to

terminating frames

Routing: routing frames to theirintendeddestinations.

The network layer builds upon the IEEE 802.15.4 MACs features to allow

extensibility of coverage. Additional clusters can be added; networks can be

consolidated or splitup.




31/51

5.3 Network Layer Security

The NWK layer also makes use of the Advanced Encryption Standard (AES).

However,unlike the MAC layer, thesecurity suitesare allbasedon the CCM mode of

operation.The CCM mode of operation is aminor modification oftheCCM mode used

by the MAC layer. It includes all of the capabilities of CCM and additionally offers

encryption-only and integrity-only capabilities. These extra capabilities simplify the

NWK layer security by eliminating the need for CTR and CBC-MAC modes. Also, the

useof CCM in all security suites allowsasinglekey tobe used for different suites. Since

a key is not strictly bound to a single security suite, an application has the flexibility

to specify the actual security suite to apply to each NWK frame, not just whethersecurity is enabledor disabled

When the NWK layer transmits (receives) a frame using a particular security suite it

uses the Security Services Provider (SSP) to process the frame. The SSP looks at the

destination (source) of the frame, retrieves the key associated with that

destination (source), and then applies the security suite to the frame. The SSP

provides the NWK layer with a primitive to apply security to outgoing frames and a

primitive to verify and remove security from incoming frames. The NWK layer is

responsible for the security processing, but the upper layers control theprocessing by

setting up the keys and determining which CCMsecuritysuite to use for each frame.

Similar to the MAC layer frame format, a frame sequence count and MIC may be

added to secure a NWKframe.




32/51

ZigBee

CHAPTER 6

ZigBee ROUTING MECHANISMS




33/51

ZigBee ROUTING MECHANISMS 6

6.0 ZigBee routing algorithm

ZigBee routing algorithm can be thought of a hierarchical routing strategy with

table-driven optimizationsapplied where possible. The routing layer issaid to start with

thewell-studiedpublicdomainalgorithm Ad hoc On Demand Distance Vector (AODV)

and Motorolas Cluster-Tree algorithm.

6.1 AODV: Ad hoc On Demand Distance Vector

AODV is a pure on-demand route acquisition algorithm: nodes that do not lie on

active paths neither maintain any routing information nor participate in any periodic

routing table exchanges. Further, a node does not have to discover and maintain a

route to another node until the two need to communicate, unless the former node is

offering services as an intermediate forwarding station to maintain connectivity

between two othernodes.

The primary objectives of the algorithm are to broadcast discovery packets only

when necessary, to distinguish between local connectivity management and

general topology maintenance and to disseminate information about changes in

local connectivity to those neighboring mobile nodes that are likely to need the

information.

When a source node needs to communicate with another node for which it has no

routing information in its table, the Path Discovery process is initiated. Every nodemaintains two separate counters: sequence number and broadcast id. The sourcenode initiates path discovery by broadcasting a route request (RREQ) packet to its

neighbors, which includes source address, source sequence number, broadcast id,destination address, destination sequence number, hop cnt. (Source sequencenumber is for maintaining freshness information about the reverse route whereas thedestination sequence numberisfor maintaining freshnessofthe routeto the destination

before it can be accepted by thesource.)

The pairsource address, broadcast iduniquely identifies a RREQ, wherebroadcast idis incremented whenever the source issues a new RREQ. When an intermediate

node receivesaRREQ, if it hasalready received aRREQ with the samebroadcast id

and source address,it drops theredundant RREQanddoesnotrebroadcast it.




34/51

Otherwise, it rebroadcasts it to its own neighbors after increasing hop cnt. Each

node keeps the following information: destination IP address, source IP address,

broadcast id, expiration time for reverse path route entry and source nodessequence number.

As the RREQ travels from a source to destinations, it automatically sets up the

reverse path from all nodes back to the source. To set up a reverse path, a noderecords the address of the neighbor from which it received the first copy of RREQ.

These reverse path route entries are maintained for at least enough time for the

RREQ to traverse thenetwork and producea replyto thesender.

Figure 6.1: Reverse and forward path forma tionin AODV protocol.

When the RREQ arrives at a node, possibly the destination itself, that possesses a

current route to the destination, the receiving node first checks that the RREQ was

received over a bi-directional link. If this node is not destination but has route to the

destination, it determines whether the route is current by comparing the destination

sequence number in its own route entry to the destination sequence number in theRREQ. If RREQs sequence number for the destination is greater than that

recorded by the intermediate node, the intermediate node must not use this route to

respond to theRREQ, instead rebroadcasts the RREQ. If the route has a destination

sequence number that is greater than that contained in the RREQ or equal to that

contained in the RREQbutasmallerhopcount,it can




35/51

unicasts aroutereplypacket(RREP)back to its neighbor from which itreceived

the RREQ. A RREP contains the following information: source address, dest addr,

dest sequence number, hop cnt and lifetime. As the RREP travels back to thesource, each node along the path sets up a forward pointer to the node from which

the RREP came, updates its timeout information for route entries to the source and

destination, and records the latest destination sequence number for the requested

destination.

Nodes that are along the path determined by the RREP will timeout after route

requestexpiration timer and willdelete the reversepointers since they are noton the

path from source to destination as shown in Figure 6.1. The value of this timeout

time depends on the size of the ad hoc network. Also, there is the routing caching

timeout that is associated with each routing entry to show the time after which the

route is considered to be invalid. Each time a route entry is used to transmit data

from a source towarda destination, the timeout for theentry isreset to thecurrenttime

plus active-route-timeout.

The source node can begin data transmission as soon as the first RREP is

received, and can laterupdate its routinginformationifit learns ofa better route.

Each routing tableentry includes the following fields: destination,nexthop, number of

hops (metric), sequence number for the destination, active neighbors for this route,and expirationtime for theroute table entry.

For path maintenance, each node keeps the address of active neighbors through

which packets for the given destination are received is maintained. This neighbor is

considered active if it originates or relays at least one packet for that destination

within the last active-timeout period. Oncethe next hop on the path from source to the

destination becomes unreachable (hello messages are not received for a certain

time, hello messages also ensures that only nodes with bidirectional connectivity

areconsidered to beneighbors, therefore each hellomessageincluded the nodes fromwhich the node has heard), the node upstream of the break propagates an

unsolicited RREP with a fresh sequence number and hop count of 1to all active

upstream nodes. This process continues until all active source nodes are notified.

Upon receiving the notification of a broken link, the source nodes can restart the

discovery process if they still require a route to the destination. If it decides that it

would like to rebuild the route to the destination, it sends out an RREQ with a

destination

sequencenumber of one greater than the previously known sequence number, to




36/51

ensure that it builds a new, viable routeand that no nodes reply if

they still regard thepreviousroute as valid.

6.2 Cluster-Tree Algorithm

The cluster-tree protocol is a protocol of the logical link and network layers that

uses link-state packets to form either a single cluster network or a potentially larger

cluster tree network. The network is basically self-organized and supports network

redundancy to attain a degreeof fault resistanceand self-repair.

Nodes select a cluster head and form a cluster according to the self-organized

manner. Then self-developed clusters connect to each other using the Designated

Device (DD).

6.2.1 Single Cluster Network

The cluster formation process begins with cluster head selection. After a cluster

head is selected, the cluster head expands links with other member nodes to form a

cluster.

After a node turns on, it scans the channels to search for aHELLO message form

other nodes (HELLO messages correspond to beacons in MAC layer of IEEE

802.15.4). If it cant get any HELLO messages for a certain time, then it turns to a

cluster head as shown in Figure 6.2 and sends out HELLO messages to its

neighbours.The new clusterheadwait for responses from neighbours for a while. If it

hasnt received any connection requests, it turns back to a regular node and

listens again. The cluster head can also be selected based on stored parameters of

each node, like transmission range, power capacity, computing ability or location

information.




37/51

Figure 6.2: Cluster head selection process.

After becoming the cluster head (CH), the node broadcasts a periodic HELLO

message that contains a part of the cluster head MAC address and node ID 0 that

indicates the cluster head. Thenodes that receive this message send a

CONNECTION REQUEST message to the cluster head. When the CH receives it, it

responds to thenodewitha CONNECTIONRESPONSE message that containsa node

IDfor the node(nodeID corresponds tothe short address at theMAClayer). Thenode

that is assigned a node ID replies with an ACK message to the cluster head. The

message exchangeisshown inFigure6.3.

Figure 6.3: Linksetup between CH andmember node.

If all nodes are located in the range of the cluster head, the topology of connection

becomes a starandeverymembernodes are connected to thecluster headwith one

hop. A clustercan expand into a multi-hopstructure wheneach node supports multiple

connections. Themessage exchange for themulti hop cluster set up procedure is

showninFigure 6.4.




38/51

Figure 6.4: Mult i hop cluster setup procedure.

If the cluster head has run outof all node IDsor the cluster has reached some other

defined limit, it should reject connection requests from new nodes. The rejection is

through the assignmentof aspecial ID to the node.

The entry of the neighbour list and the routes is updated by the periodic HELLO

message. If a node entry does not update until a certain timeout limit, it should be

eliminated.

A node may receive a HELLO message from a node that belongs to different

cluster. In that case, the node adds thecluster ID (CID)of the transmitting node in the

neighbour list and then sends it insidea LINKSTATE REPORT to theCH so that CH

knowswhich clusters its clusterhasintersection.

The LINK STATE REPORT message also contain the neighbors node ID list of the

node so that the CH knows the complete topology to make topology optimizations. If

the topology change is required, then the CH sends a TOPOLOGY UPDATE

message. If a member receives a TOPOLOGY UPDATE message that the different

parent node is linked to the node, it changes the parent node as indicated in the

message. And it also records its childnodes and the nodesbelow it in the treeat this

time.

If amember node has trouble andbecomes unable to communicate, the tree route of

the cluster would be reconfigured. The CH knows the presence of a trouble by the

periodic LINK STATE REPORT. When the cluster head has trouble, the

distribution of HELLO message is stopped and all member nodes know that they




39/51

have lost the CH. The cluster would then be reconfigured in the same way as the

cluster formation process.

6.2.2 Multi-Cluster Network

To form anetwork,aDesignated Device (DD) is needed.The DD hasresponsibility to

assign a unique cluster ID to each cluster head. This cluster ID combined with the

node ID that the CH assigns to each node within a cluster forms a logical

address and is used to route packets. Another role of the DD is to calculate the

shortest route from the cluster to the DD and inform it to all nodes within the

network.

When the DDjoins the network, it acts as the CH of cluster 0 and starts to send

HELLOmessage to the neighborhood. IfaCH has received this message, itsends a

CONNECTION REQUEST message and joins the cluster 0. After that, the CH

requestsa CID to theDD. In this case, the CH is a border node that has two logical

addresses. One is for a memberof thecluster 0and the other is for a CH. When the

CH gets a new CID, it informs itsmember nodes bythe HELLO message.

If a member has received the HELLO message from the DD, it adds CID 0 in its

neighbor list and reports to its CH. The reported CH selects the member node as a

border node to itsparent cluster and sends anetwork connection requestmessage tothe member node to set up a connection with the DD. The border node requests a

connection and joins the cluster 0 as its member node. Then it sends a CID

REQUEST message to the DD. After the CID RESPONSE message arrival, the

border node sends NETWORK CONNECTION RESPONSE message that contains a

newCIDto the CH when the CH gets anewCID, itinforms toits member nodes bythe

HELLO message.

The clusters not bordering cluster 0 use intermediate clusters to get a CID. Again,

either the CHbecomes theborder node to its parent cluster or the CH names a

member node as the border to its parent cluster. These processes are shown in

Figures 6.5,6.6,6.7,6.8.




40/51

Figure 6.5: CIDassignment 1

Figure6.6: CID assignment 2.





41/51


Each member node of the cluster has to record its parent cluster, child/lower

clusters and the border node IDsassociated with both the parent and child clusters. The

DD should storethe wholetree structure ofthe clusters.

Like thenodesintheclusters,the CHsreport their link state information to the DD. The

CHperiodically sends a NETWORK LINK STATE REPORT message that contains

its neighbor cluster CID list to the DD.Then this information can beused to calculate

theoptimizedroute and periodicallyupdatethe topology for thenetwork redundancy.Inthe same way, theDDcan sendTOPOLOGY UPDATE message to informup-to-date

route from the DDtothe clusters.

A backup DD (BDD) can be prepared to prevent network down time due to the DD

trouble. Inter-cluster communication, which is shown in Figure 6.9, is realized by routing.

The border nodes act as routers that connect clusters and relay packets between the

clusters. When a border node receives a packet, it examines the destination address,

then forwards to the next border node in the adjacent cluster or to the destination nodewithin the cluster.




42/51

Figure 6.9: A multi cluster network and the border nodes.

Only the DD can send amessage toall thenodes within its network. The message is

forwarded along the tree route of clusters. The border node should forward the

broadcast packet from the parentcluster to the childcluster.

ZigBee




43/51

CHAPTER 7

APPLICATION LAYER

APPLICATION LAYER 7

7.0 APPLICATION LAYER

The ZigBee application layer consists of the APS sub-layer, the ZDO and the

manufacturer-defined application objects. The responsibilities of the APS sub-layer

include maintaining tables for binding, which is the ability to match two devices

together based on their services and their needs, and forwarding messages

between bound devices. Another responsibility of the APS sub-layer is discovery,which is the ability to determine which other devices are operating in the personal

operating spaceof a device. The responsibilities of the ZDO include defining the role

of the device within the network (e.g., ZigBee coordinator or end device), initiating

and/or responding to binding requestsand establishing a secure relationship

between network devices. The manufacturer-defined application objects

implement the actual applications according to the ZigBee-defined

application descriptions

7.1 Application Support Layer




44/51

This layerprovides the following services:

Discovery:Theability to determine whichother devices areoperating in the

personal operatingspace ofa device.

Binding: The abilitytomatch two ormore devices together basedon their

services and their needsand forwarding messagesbetweenbounddevices

7.2 The General Operation Framework (GOF)

TheGeneralOperation Framework (GOF) is aglue layerbetween applicationsand restof the protocol stack. The GOF currently coversvarious elements that are common

for all devices. It includes sub addressing and addressing modes and device

descriptions, such as type of device, power source, sleep modes, and

coordinators. Using an object model, the GOF specifies methods, events, and data

formats that are used byapplicationprofiles to construct set/get commands and their

responses.

Actual application profiles are defined in the individual profiles of the IEEE's working

groups. EachZigBee device can support upto30 different profiles.

Currently, only one profile, Commercial and Residential Lighting, is defined. It

includes switching anddimming load controllers, corresponding remote-control

devices, and occupancy and light sensors.

7.3 ZigBee Device

There aretwophysical device types forthe lowest system cost.The IEEE standard

defines two types ofdevices:

Fullfunction device (FFD)

o Canfunction in any topologyo Capable of being the network coordinator

o Capable of being a coordinator

o Cantalk toany other device

Reduced functiondevice (RFD)

o Limited to star topology

o Cannot becomea network coordinator

o Talks only to a network coordinator

o Very simple implementation




45/51

An IEEE 802.15.4/ZigBee network requires at least one full function device as a

network coordinator, but endpoint devices may be reduced functionality devices to

reduce system cost.

Alldevicesmust have 64 bit IEEE addresses

Short (16bit) addresses can beallocated to reduce packet size

Addressing modes:

o Network +device identifier (star)

o Source/destination identifier (peer-peer)

7.4 ZigBee Device Objects

Definesthe role ofthe device within the network (e.g., ZigBee coordinator or end

device)

Initiates and/or responds to bindingrequests

Establishesasecure relationship between networkdevices selecting oneof

ZigBees security methodssuchaspublic key, symmetric key, etc.

ZigBee




46/51

CHAPTER 8

ZigBee -APPLICATIONS

ZigBee - APPLICATIONS 8

8.1 Product Examples

Warehouses,Fleetmanagement, Factory, Supermarkets, Office complexes Gas/Water/Electric meter, HVAC

Smoke, CO,H2O detector

Refrigerationcase or appliance

Equipment management services& PM

Securityservices

Lightingcontrol

Assembly line andwork flow, Inventory

Materialsprocessing systems(heat, gasflow, cooling, chemical)

Energy, diagnostics,e-Business services Gateway or Field Servicelinksto sensors& equipment




47/51

Monitoredto suggest PM, productupdates, status changes

Nodes link toPC for database storage

PC Modem calls retailer, ServiceProvider, or Corpheadquarters

Corp headquarters remotelymonitorsassets, billing, energymanagement

8.2 Home & Diagnostics Examples

Mobile clients link to PC for database storage

PC links toperipherals,interactive toys

PC Modem calls retailer, SOHO,Service Provider

Gateway links to security system, temperaturesensor,AC system,entertainment, health.

Gateway links to field sales/service

ZigBee




48/51

ZigBee

CONCLUSION

CONCLUSION 9

IEEE 802.15.4 is a new standard that still needs to pass through the circles of

rigorous technology critics and establish its own place in the industry. Predictions for

the future of ZigBee-enabled devices are a popular topic for numerous market-research firms.

While I intend to stay objective, I believe, based on protocol features implemented in

802.15.4, that ZigBee has a bright future. Backed by IEEE, ZigBee has the

potential to unify methods of data communication for sensors, actuators,

appliances, and asset-tracking devices. It offers a means to build a reliable but

affordable network backbone that takes advantage of battery-operated devices with a

low data rate and a low duty cycle. ZigBee can be used in manyapplications, from




49/51

industrial automation, utility metering, and building control to even toys. Home

automation, however, is the biggest market for ZigBee-enabled devices. This

follows from the number of remote controlled devices (or devices that may be

connected wirelessly) in the average household. This cost-effective and easy-to-

use home network potentially creates a whole new ecosystem of interconnected

home appliances, light and climate control systems, and security and sensor sub

networks.

ZigBee




50/51

ZigBee

BIBILOGRAPHY

BIBLIOGRAPHY

On theweb

ZigBeeAlliance,http://www.caba.org/standard/zigbee.html.

ZigBeeAlliance,http://www.zigbee.org

IEEE802.15.4 web site,http://www.ieee802.org/15/pub/TG4.html

http://wireless.weblogsinc.com/entry/1234000283039483/

On thepress

LAN-MANStandardsCommitteeof the IEEE ComputerSociety,Wireless Medium

Access Control (MAC) and Physical Layer (PHY) Specifications forLow-Rate Wireless PersonalArea Networks (LR-WPANs), IEEE,2003




51/51

IEEEP802.15 WorkingGroup for WPANs,Cluster Tree Network


zigbee networks

Documents