2.1 Preface

This chapter discusses thorough knowledge of the research, theory, concepts,

ideology and opinion related to the title which are Zigbee technology, concept, and wireless

sensor network that help in developing this project. The chapter also elaborates the function

and application of each technology discussed. Research and finding is prepared in order to

give inspiration to design and develop automation system based on ZigBee communication,

thus achieve the objective of this project.

2.2.1 Automation System

Evolved of the technology make people life much easier and efficient. Many user, whether

they realize it or not, they are depends many things with smartphone. One of the technologies

that began to spread widely is home automation system. Many market researchers have been

doing their analysis and build a prototype so that this system can be outfitting in the home by

the near future.

The home automation refers to domestic environment that improves the quality of the

resident’s life by facilitating a flexible, comfortable, healthy, and safe environment. Internet

based home automation system become the most popular home automation system in

international markets. The remote controlling and monitoring of a house using internet

requires a computer, which is large in size and heavy to carry around [2].

The most available home automation system use different wireless communication standard

to exchange data and signalling between their components, like Bluetooth, ZigBee, Wi-Fi,

and finally the Global System for Mobile Communication (GSM). Wireless based home

automation system decrease installation cost and effort, and enhances system flexibility and

scalability [2].

Various smart home systems has been proposed where the control is via Bluetooth, internet,

short message services (SMS) based, while some researchers have proposed voice controlled

smart home system based on Microsoft speech recognition and microcontroller based voice

activation (voice recognition module is used) [1].

In this project, refrigerator automation system would be the specific topic. Refrigerator is one

of the household that people tend to overlooked. Despite that, there are actually many

experimental study has been made for the refrigerator and most of it is related for them to

find ways to save energy efficiently.

Relation to this project, based on the objective that has been made which is this application

can notify the user about the changes of the temperatures and to control the switch of the

refrigerator. By looking at this objective, it shows that this project does related in term to save

energy for household such other researcher did.

2.2.2 Automation Control System Vs. People Operation

Any man-made system cannot exclude the influence of the people who devise and operate it.

Firstly, establishment of any automation control system, even advanced system, should meet

the need of man-kind. In other words, people are always subject, and automation system is

only object.

The development of making the goal, the strategy, the plan, and even details of the

automation system should depend on the request of the people, so the need of people is

always the core of system. Perfect automation control system provides outstanding serve for

people, while bad automation system may create disasters [3].

Figure 1: Example design for automation system

2.2.3 ZigBee

ZigBee is the set of specs built around the IEEE 802.15.4 wireless protocol. Zigbee has been

developed to meet the growing demand for capable wireless networking between numerous

low-power devices. In industry, it 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 kind level of communication permits finely-tuned remote

monitoring and manipulation. In the consumer market, the technology is being explored for

everything from linking low-power household devices.

The specified maximum range of operation for ZigBee devices is 250 feet (76 m). Due to its

low power output, ZigBee devices can sustain themselves on a small battery for many

months, or even years, making them ideal for install-and-forget purposes.

2.2.4 DC Motor

DC motor, with the features of wide range of step less speed regulation, strong overload

capacity, fast response speed, good stability, and ease of maintenance and so on, applies in

various fields [4]. A DC motor relies on the facts that like magnet poles repels and unlike

magnetic poles attract each other. A coil of wire with current running through it generates an

electromagnetic field aligned with the center of the coil. By switching the current on or off in

a coil its magnetic field can be switched on or off by switching the direction of the current in

the coil the direction of the generated magnetic field can be switched 180 degree.

A simple DC motor typically has a stationary set of magnets in the stator and an armature

with a series of two or more windings of wire wrapped in insulated stack slots around iron

pole pieces with the end of the wires terminating on a commutator. The armature includes the

mounting bearings that keep it in the center of the motor and the power shaft of the motor and

the commutator connections.

The winding in the armature continues to loop all the way around the armature and uses

either single or parallel conductors (wires), and can circle several times around the stack

teeth. The total amount of current sent to the coil, the coil’s size and what it’s wrapped

around dictate the strength of the electromagnetic field created. The sequence of turning a

particular coil on or off dictates what direction the effective electromagnetic fields are

pointed.

By turning on or off coils in sequence a rotating magnetic field can be created. The rotating

magnetic fields of the magnet (permanent or electromagnets) in the stationary part of the

motor (stator) are to create a force on the armature which causes it to rotate. In some DC

motor designs, the satator fields use electromagnets to create their magnetic fields use

electromagnets which allow greater control over the motor. At high power levels, DC motors

are almost cooled using forced air.

2.3 Concept

Mini version of WiFi has often been regarded for ZigBee. ZigBee and WiFi are often used

together in the same applications in terms of household based wireless communication. Even

they might have many similarities they both have been proposed and developed in a different

mindset and hence some significant differences exist between these two.

IEEE Standard

- Wi-Fi has been standardized under IEEE 802.11.x standard. There are several

versions of the protocol where x gets replaced by a, b, g, n etc. which are

different versions of Wi-Fi. Zigbee comes under 802.15.4 IEEE standard.

 

Caretaker Alliance

- Wi-Fi is managed and its certification process is taken by Wi-Fi Alliance, an

independent group constituted by several electronics and communication

companies. On similar grounds, Zigbee also has a separate alliance that takes

of Zigbee based product development and certification processes.

Development Timeline

- The idea for Wi-Fi came out as an alternative to ease work of cashier

machines in the year 1985. A community to standardize was established in the

year 1990 which launched the standard in the year 1997.

- On the other hand, idea was Zigbee was conceived in the year 1999, when it

was found that for some long running applications, Wi-Fi and Bluetooth were

not prepared. It was launched in the year 2004.

Operating Frequency

- Wi-Fi is known to work at 2.4GHz, 5GHz, though there have been recent

developments where Wi-Fi is working at 60GHz frequency. Zigbee, works at

900-928 MHz and 2.4GHz. Besides that Zigbee protocol has a specific

frequency of 868 MHz for European countries.

Channel Bandwidth

- Zigbee protocol based communications have a channel bandwidth of 1MHz

while Wi-Fi channels have a bandwidth of 0.3, 0.6 or 2MHz.

Network Range

- Zigbee is restricted to Wireless Personal Area Networks (WPAN), reaching

10-30meter in usual applications. Recently, there have been some applications

which tend to reach 100m in terms of range. Wi-Fi serves up for PAN and

WLAN area networks with an average range between 30 to 100 meters.

 

Data transfer speed

- Wi-Fi networks, though faster than zigbee in terms of data transfer, show

variation in terms of speed. Wi-Fi networks defined under 802.11b standard

have maximum data transfer speed of 11mbps while a and c versions have

54mbps of maximum data transfer speed. Maximum speed in zigbee networks

is only 250kbps, fairly low than the lowest Wi-Fi offers.

 

Bit Time

- It can be defined as time taken to transmit one bit at a given data rate of

transfer.  Bit time in zigbee is 4micro seconds while in Wi-Fi it is only

0.00185 micro seconds.

 

Power Consumption 

- Wi-Fi, though now having a low power version over the horizon, has not been

known as a power efficient network. Wi-Fi based devices need a good battery

back-up if one wants to use them for more than 10hours or so. On the other

hand, Zigbee protocol has been designed for “assemble and forget” manner.

These are extremely minimal in terms of power consumption and hence can go

on for weeks and months. In general, Zigbee based networks consume 1/4th of

the power consumed by Wi-Fi networks.

 

Network Elements

- In a standard point to point network, two stations can be connected to each

other. A Wi-Fi router is also needed in some places where one needs to

connect multiple devices to each other and/or wants to connect to the internet.

- In Zigbee, the network elements can be broadly classified into three types:

Zigbee coordinator, Zigbee end router, Zigbee end device.

 

Network Size

- A single Wi-Fi based network can have a network size of up to 2007 nodes

whereas Zigbee based networks can have over 65,000 nodes in one such

network.

 

Network Security

- Zigbee protocols use Advanced Encryption Security (AES) methods for

encryption and CCB-CCM methods for network security. On the other hand,

Wi-Fi based networks use WEP, WPA and WPA2 protocols for network

encryption and security, respectively.

2.4 Research Study

Before continuing next phases, study from previous project has been made and be compared.

This is important as to study the implementation and also the design. The previous project

that has been studied is related in term of automation system.

2.4.1 Android Based Smart Home System with Control via Bluetooth and Internet

Connectivity.

This project has been done student from School of Engineering and Physics from University

of the South Pacific, Suva, Fiji and also by a senior member of IEEE from departments of

Electronics Engineering from Mokpo National University.

Market researchers claimed that in the near future, majority of homes will be outfitted with

home automation system. There are also many proposed from previous project which are by

collaboration via Bluetooth, internet, short message service (SMS) based, voice controlled

smart home system based on Microsoft speech recognition and microcontroller based voice

activation.

For this project they choose a low-cost and flexible standalone smartphone system. The

interoperable layer, the system is Bluetooth and REST ful based web services. For the

application, it was based on Android. Arduino Ethernet acts as the main controller. The

hardware they used is siren, nRF24L01+ radio control. For switching functionalities it is

supports voice activation for switching functionalities.

The master controller for this system supports Bluetooth and internet connectivity. But only

one type of connection is allowed at one time.

The results for this project is successfully developed and tested. What makes the project

unique is because it has a lot of features in one system but still in a low cost and can work

really effective.

2.4.2 An Android Based Home Automation

This project has been done by group from Department of Software Engineering at Izmir

University of Economics Balcova. Their project is based on other previous work which

proposed the use of home automation system based on Android.

The oldest standard of home automation system is XIO industry which founded in 1975. But

it developed limited control over household devices through home’s power lines. In this

project they did some research on some collaboration with other technologies based on other

project. They are, Java technology and Bluetooth, but they find it interesting as phone based

remote control system is being proposed.

They find that using remote control phone based does have a lot of advantage in terms it can

be accessed by any telephone. The disadvantage is that, it lacks of graphical user interface

(GUI) and for the user to remember user access code and devices code.

After discussing, they decide to use ZigBee and WiFi network. They decide so because

ZigBee can lowering the intrusiveness of the respective system installation and also the

expense of the system which is better compared to other technologies.

For this home automation system, infrastructure design that they use is a top-view

communication diagram. The 3 main components for this project is local hardware, web

server and mobile smar device. Hardware that this project use is i.MX53 card and the web

server is Google Cloud Messaging (GCM) and mobile smart device is based on Android.

Each of the components has its own purposes. As for local devices, the purpose is to transfer

signals to home appliances. Web server as storage of customer records and to support

services to other components and for mobile smart device that has an Android based

application. Different function for each components of the system are define and also the

infrastructure. To support messaging between the components, distributed cloud platforms

and services of Google are used.

2.4.3 Comparison between previous project and current project.

Table 2 shows comparison between two previous projects and also compared to the current

project

An Android Based

Home Automation

System

Android Based

Smart Home System

with Control via

Bluetooth and

Internet

Connectivity

Current project

(2014)

Way of work i.MX53 card records

the updated data and

regularly sends

session data to its

serial port

Arduino Mega 2560

and Arduino

Ethernet Sield with

siren is used to

communicate and

coordinate actions

with the other

sensor nodes within

the home

environment and the

Bluetooth module.

Alarm will detected

state of the door and

will alert if it does

not closed properly

after certain period

of time and will

notify user if the

door still does not

closed properly.

System design Use i.MX53 card and

wireless or wired

equipment to connect

to the appliances.

Uses Bluetooth and

REST ful based web

services

Use XBee as

transceiver and

alarm to alert the

user.

GUI design .Have the same GUI

design for both

i.MX53 and also

mobile smart device.

Massachusetts

Institute of

Technology App

Inventor

Friendly user and

simple yet has all

required information

Implementation

cost

Low: Requires one

i.MX53 card and

some equipment to

connect appliances

Low: use two

Arduino as main

controller and siren.

Low: requires only

transceiver and one

alarm.