Final Year Thesis (1)

University of Wales

Faculty of Computing

Mobile Communication (Analysis of energy consumption in

3G and Wi-Fi)

MSc Thesis

Course: MSc In ComputingSupervisor: Prof. Jim Matthews

http://www.wales.ac.uk/default.asp

Analysis of energy consumption in 3G and Wi-Fi

Thesis author consent form

DECLARATION

I, Sharif Kamal, hereby declare that the dissertation titled: Mobile Communication (Analysis of

energy consumption in 3G and Wi-Fi) is a bona fide record done by me during the course of

MSc in Computing and has not previously formed the basis for the award of any degree,

diploma, fellowship or other similar title of any other university.

______________________________

Date: 10/December/2010 Sharif Kamal

KCB ID: 12915

Campus: Kensington College of Business, London

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Abstract

This paper gives an idea about energy consumption of mobile devices which are having both

networks means 3G and Wi-Fi. Analysis of energy consumption in 3G and Wi-Fi is the main aim

of the paper.

Modern generation or lives are more dependent of Cellular phones. Mobile devices, personal

Digital Assistants (PDA), Portable Information Devices (PIDs) etc these devices are often

running on battery power. These devices are having expected battery lifetime. Therefore energy

conservation in these devices is paramount concern.

Now a day’s mobile phones are everywhere with estimated subscription of more than 4 billion

around the world. Almost all phones support both 3G and Wi-Fi networks to data transfer. The

3G uses is about 15% in worldwide and 70% in some countries. [1]

How does power consumption occurs in 3G and Wi-Fi? What characteristics of energy

consumption in 3G and Wi-Fi differ? Which network is more energy efficient? To find out these

questions answers, this paper conduct detailed measurement study of power consumed by data

transfer across 3G and Wi-Fi.

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Acknowledgement

While working of assigned project, I learnt number of things in depth knowledge of the topic.

This was possible because I have been guided by my supervisor Prof. Ben Allen in a way that

makes things easy and understandable to me and as well to others who will reach to my project.

Initially I was nervous and could not understand how to start this but I would like to say a big

thank to my supervisor Prof. Jim Mathews who has approached me in a manner that makes

everything so easy to me and now I am in position to feel confident to start any new task in my

future assignment.

I would like to say thanks to my parents, who are always with me and motivates me always.

Because of them I can see myself on this position.

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Dedication

“I feel proud to dedicate my project to my loving parents.”

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Table of Content

Chapter 1

INTRODUCTION .........................................................................................................................8

1.1. Background .............................................................................................................................8

1.2. Problem Context .....................................................................................................................9

1.3. Motivation .............................................................................................................................10

1.4. Aim and Objectives ...............................................................................................................14

Chapter 2: Literature Review

OVERVIEW OF 3G AND WI-FI 802.11X .................................................................................16

2.1. Evolution of 3G ....................................................................................................................16

2.1.1. 1st Generation ....................................................................................................................16

2.1.2. 2nd Generation ...................................................................................................................16

2.1.3. 3rd Generation ...................................................................................................................16

2.2. General background of 3G ....................................................................................................17

2.3. 3G requirements ....................................................................................................................18

2.4. Advantages and Disadvantages over other cellular technologies .........................................18

2.5. Evolution of Wi-Fi ................................................................................................................20

2.6. General background of Wi-Fi ................................................................................................20

2.7. Components of Wi-Fi ...........................................................................................................22

2.8. Scanning ................................................................................................................................24

2.9. Power Management ..............................................................................................................25

2.10. Advantages and Disadvantages ...........................................................................................27

Chapter 3: Research methodology

ENERGY CONSUMPTION IN 3G AND WI-FI ........................................................................30

3.1. Basic principle of energy consumption .................................................................................35

3.1.1. Power (Link budget) calculation for 3G ............................................................................37

3.2. 3G power control algorithm 25 3.3. Wi-Fi power control algorithm ...................................39

3.3.1. Wi-Fi power control algorithm ..........................................................................................41

3.3.2. How WMM Work? ...........................................................................................................43

3.4. Different parameters in 3G & Wi-Fi .....................................................................................44

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3.5. Parameters of energy consumption........................................................................................45

Chapter 4: Evolution

EXPLORATION, RESULTS AND ANALYSIS, FLOW CHART ............................................46

4.1. 3G vs. Wi-Fi ..........................................................................................................................47

4.2. Voice communication over 3G & WI-Fi ..............................................................................52

4.3. Flow chart .............................................................................................................................55

Chapter 5: Conclusion

CONCLUSIONS ..........................................................................................................................56

5.1. Conclusion .............................................................................................................................56

5.2. Future work (experimental work) .........................................................................................57

5.3. Energy saving techniques .....................................................................................................57

REFERENCES ............................................................................................................................58

Appendices ...................................................................................................................................59

Appendix 1(Poster) ......................................................................................................................60

Appendix2 (Gantt chart) ..............................................................................................................61

Appendix 3 (List of figures) .........................................................................................................62

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1.0 Introduction

Background:

In the past few years the growth of wireless industry is tremendously increasing, both in WAN

(Wide Area Network) and LAN (Local Area Network). So the network providers realize that the

importance of efficient network. The huge competition arrived in network providers. To give an

efficient network services they started to research and develop more and more efficient network.

Today we can use internet anywhere in the world, we can make call or communicate with our

friends, family, business partner, and colleague very easily. Now it is possible to make video

calls also with the help of Skype, Gtalk, Yahoo messenger etc over VoIP. All of these facilities

become possible because of development of communication media.

The wireless network is the most improved and developed technology. In WAN we are using 3G

with the very good mobility, and in LAN we are using Wi-Fi with the very good speed of data

rate. User equipments of these both networks are running on battery supply.

This paper gives an idea about energy consumption of mobile devices which are having both

networks means 3G and Wi-Fi. Analysis of energy consumption in 3G and Wi-Fi is the main aim

of the paper. Modern generation or lives are more dependent of Cellular phones. Mobile devices,

personal Digital Assistants (PDA), Portable Information Devices (PIDs) etc these devices are

running on battery power only. These devices are having expected battery lifetime. Therefore

energy conservation in these devices is paramount concern.

Now a day’s mobile phones are everywhere with estimated subscription of more than 4 billion

around the world. Almost all phones support both 3G and Wi-Fi networks to data transfer. The

3G uses is about 15% in worldwide, and 70% in some countries.[1]

How does power consumption occurs in 3G and Wi-Fi? What characteristics of energy

consumption in 3G and Wi-Fi differ? Which network is more energy efficient? To find out these

questions answers, this paper conduct detailed measurement study of power consumed by data

transfer across 3G and Wi-Fi.

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Problem Context:

This research provides more idea about 3G and Wi-Fi. Nowadays both technologies are

available in single device e.g. mobile phones. But if we think about power consume by

both technologies then it is quite interesting that which network or technology we are

going to choose. Because one person’s device is having low battery or fully charged, then

he needs to take correct decision.

Figure1.1: (An idea about battery consume by Mobile “iphone” For all applications) [10]

Above figure gives an idea about energy consume by 3G and Wi-Fi. This software

provided by iphone iTunes store. In this figure we can find out battery is 80% remain and

according to that this application tells how much you can use battery per application. For

example for 3G internet you can use 4:00 hours and for Wi-Fi internet 4:48 hours etc.

Then he has to calculate the time how much he can use his device with both technology,

and then only he can choose 3G or Wi-Fi technology.

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But we can’t immediately say that choose this technology because both technologies are

having some advantages and disadvantages that makes both technologies different. This

research paper going to give some more details about power consume by 3G and Wi-Fi.

Motivation:

3G and Wi-Fi both are wireless technologies and mostly running on battery power

supply. So they need to recharge frequently. Almost we use both technologies for same

purpose like browsing net, video call, Skype, transfer data etc. If we are using both

technologies for same purpose then we has to find out advantages and disadvantages of

both, so that we can choose particular network according to our requirements. There are

number of parameters makes them different like bandwidth, frequency, Data rate, Energy

consumption etc. The analysis energy consumption is main motivation of this research

paper.

Mobile phones and their network variegate very momentously from supplier to supplier

and country to country. However the primary communication system of all of them is

through the electro magnetic waves with a cell found station. The cellular phone

providers have a number of antennas, which are basically attached over towers, multi

storied buildings and poles. Mobile phones have low-power communicators that transmit

verbal and data to the closest sites usually within the 5 to 8 miles (8 to 13 kilometers

away).

When a cellular device or phone is switched on, it subscribes with the cellular phone

exchange or switch-hub. It is a one-unique detector and is alerted by the cellular switch-

hub when there is an incoming cellular call.

The cellular device receives the strong communication signals from the closest found

stations. When a caller moves, the cellular device handoff to various nearest sites during

phone calls or while waiting between calls it reselect the nearest cell phone sites.

Mobile phone sites have comparatively less power radio transmitter. They transmit their

presence and pass on transitions between the cellular devices and the switch-hub. On the

other hand, the switch-hub helps to connect the call to the same or another cellular

network or user.

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The quotation between the cellular phone device and the cell phone site is a blow of the

digital-data, which adds the digitized verbal data. This technology relies on the same

technology as of cellular phone operator. Some cellular phone systems have follows the

AMPS for the analog-transmission and Universal Mobile Telecommunications Service

(UMTS), D AMPS, Code Division Multiple Access (CDMA2000) Evolution Data

Optimized (EVDO), GLOBAL SYSTEM for MOBILE (GSM) and GENERAL

POCKET RADIO SERVICE (GPRS) for the digital-transmission. Each cellular network

has a one-unique radio transmission signal.

There are different cellular communication methods, such as Short Message

Service(SMS), Wireless Application Protocol(WAP), Wireless Local Area

Network(WLAN), Wireless Fidelity(WIFI), General Pocket Radio Service(GPRS),

Bluetooth, Infrared, IrDA, I-Phone, HTC and Windows mobile etc. Mobile devices are

different by the cordless telephones the reason is they only can operate in specific area.

Many kinds of the mobile computers have been invented including the Laptop computer,

Notebook, Portable data terminal(PDT), Personal digital assistance(PDA), Tablet PC and

smart phone.

It has not been more than five decades yet, but the persistence and great imaginativeness

of discoverer have accepted the telephone- which by far, is the most great transmission

tool in this global market- to develop and get mobility. People will not have to stay home

or at work to wait for an important telephone calls. The first mobile phone has been

introduced; a cellular phone company of Japan launched 3G -- a technology that carries

multimedia and communications to perfect system.

Telecommunication criterion have developed till now another time, presenting the

advanced Third-Generation or 3G of IMT-2000, which newly surmounted 2.5G and

introduce users with an grand list of characteristics and capableness. Presented for the

first time by Japan's NTT DoComo in 2001, 3G networks can reach data rates o .f 5.8

Mbit/s on the uplink and 14.4Mbit/s on the downlink.

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The International Telecommunication Union presents standards for 3G

communications’. The two types of 3G networks Code Division Multiple

Access(CDMA) and TDMA. The Code Division Multiple Access bears the lead carriers

for 3G, consisting of Code Division Multiple Access(CDMA2000), Wideband Code

Division Multiple Access(CDMA), and Time Division Synchronous Code Division

Multiple Access(TD-SCDMA). The Wideband Code Division Multiple Access that

operates at 2.1 GHz becomes the Universal Mobile Tele-communications System as

accepted within Asia, Europe, and Japan.

The past 2G network allows seam less mobile communications, fine verbal calls and easy

electronic mail messaging. On the most newly replaced 2.5G, three minute MP3s took six

to nine minutes to be downloaded. 3G networks, however, allows verbal and data calls

(fax), worldwide roaming features, sending, receiving and transmitting of a large number

email messages with attachment files, Internet positioning capableness, video chatting

and Television streaming. A three minute song might be downloaded between 13 seconds

to 1.2 minutes.

3G accepts cellular phone subscribers to stop inside the needs of their jobs or whims just

about any time. There are unlimited multimedia accesses, where images, data documents,

and audio music may be ex-changed at critical rates without the limitation of a non

mobile desk top. One can almost work using his cellular phone with Third Generation or

3G. Using the same technologies, transmission experts can manage to harness Third

Generation or 3G and change it into mobile. Internet Protocol or IP, that’s why Internet

connectivity in the stage of T-sticks may be taken any where with a laptop computer and

have invariable connection to the World Wide Web. Data may be transmitted and

received in speeds up to 2Mbps.

Time manage is also made easy with Third Generation or 3G. Everyone who are using

technologies can order some foods, make a reservations, hire a cab, doctor's

appointments, pay bills, update their accounts, transfer money from one bank to another,

call a web-conference from across the globe, and acquire tutorials.

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Cellular phone companies will have to spend a large number of dollars to improve their

found stations to Third Generation or 3G, and there’d be found stations stated relatively

close each other to brand stronger Third Generation or 3G connections. Aside from the

substructure costs, there are almost unlimited licensing spend that will have to be

carefully weighed. Furthermore, the devices or the cellular phones are so expensive, so

it's hard to hook people to buy the devices and use the applied system to ensure the profit

of investment.

One of the main harms that present it is the previously restricted range available for

communications. The left over free range has to be used to its most potential, increase

range technology presenting itself as a apposite means of rising performance. Splitting up

of the surroundings into a figure of little cells also increases the largely handy bandwidth

of the communiqué system, but also raises the charge as extra cell sites are necessary.

Techniques such as variety combining can as well be used to raise the accessible

bandwidth from side to side superior response capabilities.

Where a large amount of devices, every being of a short power, are transmitting, a

resizable number of radio powers are being generated. The belongings of radio

communication on human being physical condition are being examined, though much

extra work is necessary in this region previous to large level communication systems are

urbanized.

The free nature of the communication interface of radio needs the subject of network

safety to be addressed. Verification of communication bodies must also be carried out to

make sure that only listed devices may communicate utilizing the network, and that only

listed devices may obtain the data. Some outline of encryption may be needs for

communications to keep away from interception of data broadcast above the network by

devices not taking part in the means of communication.

In supplement to safety considerations from exterior devices approaching the network,

intrusive signals can be produced by other devices in the workplace surrounding, for

example printers and other electro mechanical devices. These devices can provisionally

disturb a communication linkage from side to side the noise that they produce.

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A wireless communication technique has an amount of advantages, not slightest of the

mobility of the devices within the surroundings. It is a regular matter to reposition a

communicating device, and no extra cost of rewiring and extreme down time is connected

with such a be in motion. It is as well a straightforward stuff to insert in a communication

device to the method or erase one from the method without any trouble to the leftover of

the method. Other than the preliminary outlay on locate up the section sites, the outlay of

running and continuing a radio founded communications solution is smallest. These, and

extra factors, show the charm that a radio communication method has for the working

place surroundings.

Aim and objective:

The advantage of wireless network is MS (mobile station) doesn’t require being in

particular location. To take total advantage of mobility, need to consider electrical power.

Most of the mobile devices run only on battery. But we know that battery is scarce

resource. Batteries can only run so long they require recharging frequently. So the mobile

users need to always return to commercial power supply, which we know it is not

convenient. For this reason many wireless applications require long battery life without

sacrificing network connectivity.

Now day’s people got conscious about energy consumption. Whenever people go to buy

any electronic device like mobile phone, they first use to ask “what is battery backup?

How long I can use mobile without charging battery?” etc.

The main aim of this research paper is to provide proper information about energy

consumption in both technologies i.e. 3G and Wi-Fi. Along this research paper going to

provide some parameters like link budgets, Energy per bit per noise (Eb/No), Power

control mechanism and both technologies general background because it will helpful to

understand more easily. And also:

To make the mobile, wireless to be more interactive in learning available to all

consumers without incurring the expense of power consumption;

To deliver the infrastructure, information and guide to the vast numbers of people

regardless where they live on the world;

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Making a fusion of mobile technologies and WiFi’s power consumption into less

consuming to improve interactivity and connectivity for the learner;

Combining the current proliferation of the mobile and WiFi systems services and their

many users.

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2.0 Literature review of 3G and Wifi

2.1 Evolution of 3G:

The 3rd generation communication system is a big thing of wireless communication

system. First generation is based on Analogue phones, like TACS (Total Access

Communications Systems), NMT (Nordic Mobile Telephone) and AMPS (Advanced

Mobile Phone Service). The 2nd generation is a digital phone. Like GSM (Global System

for Mobile), D-AMPS. [14].

2.1.1. 1st generation:

1st generation system is launched in three decade before means in1980. In this the area of

coverage is divide in to number of small cells. So that we can sue same frequencies can

be sure number of times without interference. It gives more system capacity. For traffic

control they have used analogue transmission technique. We can say only voice

transmission. [14].

2.1.2. 2nd generation:

The 2nd generation is based on digital transmission for traffic control. Compare to 1st

generation the 2nd generation is having more capacity. The reason is channel is divided

in to the several parts, by using TDMA, FDMA or CDMA technologies. To enhance the

capacity it is using hierarchical cells, i.e. the area is covered by Pico cells, Micro cells

and Macro cells. [14].

In the 2nd generation four standards are used. Like GSM, D-AMPS, CDMA (IS-95) and

PDC. In four of this the most popular and widely used one is GSM.

In the middle of 2G and 3G we have 2.5G. It is having technologies like HSCSD, GPRS,

EDGE and IS-95.

2.1.3. 3rd generation:

The research and development of third generation project has been started in 1998 by

3GPP. The first time 3G was launched in Japan by DOCOMO in 2001. After that slowly

other companies also started to launch 3G in rest of world. Up to 2007 the 40 countries

have been started 3G network.

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Before 3G we were using 2nd generation and 1st generation so let’s have look them also,

so we get an idea about cellular wireless communication. [14].

The 1st generation was an analog cellular system. The 2nd generation system is using

digital technology, such as GSM, CDMAOne (IS-95), PDC, and IS-136(US-TDMA).

The second generation is having services like text messages, and access data.

The 3rd generation’s main aim is to access internet, and multimedia communication.

With the higher data rate, it gives more flexibility and high quality of voice and video

calling as well. [14].

Figure2.1: (Evolution of 3G) [13].

Above figure shows evolution of 2G, 3G and so on. Here we can see revolutionary steps

of future networks. In this figure we can see the data rate of all generations and

technologies.

2.2. General Background:

The 3GPP was developed to organize various groups’ technical actions and help out for

details. Number of regional standards was developed, as like CDMA2000 and W-CDMA.

Let us see now some features of both CDMA2000 and W-CDMA. [8]

Modulation QPSK QPSK

Multiple Access FDD,TDD FDD

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Mode

Channel

Bandwidth

5 MHz 1.25 * N MHz, N may be 1,2,3 later it may

be 6,9, or 12

Speech Coding AMR AMR

Spectrum

Allocation

1920-1980MHz

uplink

2110-2170 MHz

downlink

1850-1910 MHz uplink

1930-1990 MHz downlink

Frame Structure 10ms 20ms

Data transfer 144kb/s to 2048 kb/s 144kb/s to 2048 kb/s

Table2.1: (features of W-CDMA and cdma2000) [8]

2.3 3G Requirements:

The 3G system run in different environments likes indoor, outdoor, rural, urban and

suburban. The 3G is having the capabilities of transfer data such as audio, image, video,

text. For this kind of data transfer 3G requires. [8]

144 kbps in vehicle

384 kbps for pedestrians

2 Mbps for indoor

The cell size is also matters, the cell size could be

The mega cell should be more than 35 km radius

Macro cell should be 1 to 35 km

Microcell should be up to 1km

And Pico cells should be at least 50m.

2.4 Advantages & Disadvantages over other cellular technologies:

The 3G is the most popular and widely used technology among others. It is having some

advantages as well as some disadvantages also.

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2.4.1 Advantages:

Most important is its data rate. It is having 2Mbps data rate for indoor use and

while outdoor it may vary from 144Kbps to 384Kbps. Compare to 2G and 2.5G it

is very good as they offer less than 144Kbps data rate only.

Second most important is it is having soft handover mechanism. I.e. while drying

car we can be stay connected without any interference. Call can be easily

handover to another Base station because they are using same frequency.

Mega cells are having 35 km area radius, so it gives very nice mobility compare

to older technologies like 1G and 2G.

The close loop power control mechanism gives advantage to all mobile stations. It

does not matter distance between base station to mobile station.

Very good Bandwidth compare to 2G. So number of Mobile station can be easily

stay connected.

2.4.2 Disadvantages:

Main disadvantage is its cost. Compare to 2G and 2.5G it is very expensive.

Second one is high battery consumption of mobile station as compare to others are more

energy efficient.

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An Overview of Wi-Fi

2.5 Evolution of Wi-Fi:

IEEE

Standard

Speed Frequency

band

Modulation Bandwidth Release

802.11 1 Mbps-

2mbps

2.4GHz DSSS, FHSS 20 June

1997

802.11a Up to 54

Mbps

5 GHz OFDM 20 Sep 1999

802.11b Up to

11Mbps

2.4GHz DSSS 20 Sep 1999

802.11g 54 Mbps 2.4GHz OFDM,

DSSS

20 Jun 2003

802.11n 72.2Mbps

150Mbps

2.4GHZ

5GHz

OFDM 20

40

Oct 2009

Table 2.2: (Evolution of Wi-Fi)

Here above table can explain lot of things about Evolution of Wi-Fi, from 802.11 to

802.11n. Step by step as date of release, Data rate in mbps, Frequency band, and

Modulation techniques, Bandwidth of all Standards.

2.6 General background:

To get understand Wi-Fi we need to find out basics concepts of wireless, and how the

protocols are designed. Basically 802.11 is apparently similar to Ethernet. By

understanding the Ethernet it helps to understand 802.11 families. But in Wi-Fi number

of other management features is added. The 802.11 is based on MAC. The 48-bit MAC

Address is assigned for wireless interface card to all practical assignment. Both

technologies i.e. Ethernet and Wi-Fi differ from each other like Wi-Fi is having mobility

advantages but Ethernet is not having mobility. Wi-Fi devices can move easily from one

place to another. [12]

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802.11 is a family member of IEEE 802 standard. From below diagram we will get some

idea about 802.11 families. It is a nothing but a series of specifications design for Local

area network technologies. [12]

Figure2.2: (IEEE 802 family and its OSI model) [12]

The specifications of IEEE 802 are based on physical and data link layer of the OSI layer.

The 802 network is having both physical and MAC component as shown in figure above.

The determination of access the medium and send data is set by MAC layer, while

physical layer determines details of transmission and reception. [12]

In the 802 series individual specifications are determine by second number. Like 802.3 is

for CSMA/CD. For token ring it is 802.5 etc as shown in figure above. 802.11 is a link

layer. It includes MAC and two physical layers. One is FHSS (Frequency Hopping

Spread-Spectrum) for physical layer and DSSS (Direct-Sequence Spread-Spectrum) for

link layer. [12]

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2.7 Components of Wi-Fi:

Figure 2.3 :( 802.11 LAN’s Components) [12]

Distribution system:

Several AP’s (Access points) are connecting to form a distribution system. Distribution

system forms a large coverage area. Logical component of 802.11 is the distribution

system. Distribution system used to forward frames to their destination. The distribution

system can be any technology, 802.11 does not specify it. Often we say to distribution

system as Backbone of the network. Ethernet is the one of them as distribution system or

Backbone. [12]

Access Point (AP):

The device which is connects to mobile stations to distribution system is called Access

point. The frames from 802.11 are converted by Access Point for distribution and vice-

versa. It is bridge between wired and wireless media. [12]

Wireless medium:

Main aim of the wireless medium is to move frames one station to another station. Here

in 802.11 we use wireless, but several different physical layers have been defined. We

have two radio frequencies RF and infrared layer. But most popular and widely used one

is RF physical layer. [12]

Stations: The stations are usually computing devices; these are basically battery operated

devices, like laptop, mobile devices and PDA etc.

2.8 Scanning:

Scanning means process of identifying network which is existing around the area. To find

out wired network is very easy, just need to look at wall for compatible cable or jack

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connector. But in wireless network, either station or access point need to find out by them

selves.

Number of types or parameters is used to scan the network. These parameters can be

specified by user. Some parameters are as below.

BSS Type: it is specifies whether to seek ad hoc network or infrastructure network or

all.

BSSID: scanning for these devices is for specific network or any willing network to

join. It is always good that setting to BSSID because it shows results for BSS as well in

the area.

SSID: it is a network name, assigns string of bits to service set. Mostly users prefer to

SSID because of network name bits sets to a human readable.

Scanning is having two types as below

1. Passive scanning: It saves battery power of station. Passive scanning doesn’t require

transmitting. Station use moves from channel to channel list, then it waits for beacon

frames, if the beacon accept and buffered it to take out information of BSS.

Figure 2.4: (Passive scanning) [12]

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The stations sweeps channel to channel to record information that beacons are receive or

not. Basically beacons are made to find out access points. Above figure shows an idea

about the passive scanning. [12]

2. Active scanning:

Station is more assertive in active scanning. The request frames are request to response

from network. Station is by self find out the network access points.

Figure2.3: (Active scanning) [12]

As shown in figure the MS (Mobile Station) transmits the probe request to both Access

Point. After gaining access to the medium, the probe request had been transmit by both

access points. Probe response respond by both access points to report their network

parameters. It is necessary to maximize channel time so that all access points can be

processed, in the large number of network. [12]

2.9 Power management in Wi-Fi

Power saving is very easy to achieve in infrastructure network. The access points are

ideal to buffer the traffic, because all traffic comes from mobile station. No need to work

out on distributed system because it is implemented each and every mobile station. The

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access point works the bulk work. Access points are always aware of the mobile stations

locations. Mobile station can communicate with access point for its power management.

But AP needs to be always remaining active. They should be always power ON mode. By

these two facts AP can manage power of MS in infrastructure network. [12]

The AP is having two power management tasks. The AP always knows the state of power

management of each and every station. AP can find out whether frame should deliver to

MS or not. The frames are already buffered in to the AP, and station is in sleep mode.

Buffer frame cannot able to wake up the MS to receive the data. AP needs to announce to

MS that some frames are waiting for it. The intervallic announcement of buffered status

can also help for power saving mode. The management of power is deliberately designed

to battery operated devices. So that MS can sleep and save the power. [12]

2.10. Advantages & disadvantages of Wi-Fi:

There are several advantages and disadvantages of Wi-Fi. Let us talk separately so that

we can get an idea about Wi-Fi.

2.10.1 Advantages:

WiFi offering one of the most common benifit in a wireless LAN (WLAN) environment

technologies is- WiFi is entirely wire or cable free. So, when someone wants to stay in

any of his/her comfort zones in the office or the house, like on a sofa in chair in the back

yard, h/she can take the laptop along with him/her and still will be allowed to gain entry

to the internet world. Nowadays, if someone is buying a new laptop or a desktop PC, an

in-built Wireless Ethernet card, WiFi, card makes it possible to use the internet. One of

the other few important advantages is to become more and more demanding and popular:

this is called hotspots. Rather than being to constricted to one’s home wired or any

wireless LAN (Local Area Network), he or she can take pleasure of the benefits from the

Internet in community common room, such as sitting lounge, air-port lounge lobbies,

cafes, hotels and motels, city airports, college and university campuses, and also more

other general areas. Raoming profile is also supported by WiFi: one can move around the

business organization and from one point of access to the another one. Another, third use

of the WiFi is the ability for frequency hopping of 802.11b and 802.11g. By this process

it allows both of the 802.11b and 802.11g cards to broadcast themselves in one or any of

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three bands available in the Channel settings, or dividing the broadcast bandwidth in

‘hops’ amd channels in between the WiFi’s.

This can enable WiFi cards to communicate on the same occasion without interfering

each other. One more major advantage as we can see is the expansion of the Wi-Fi

Alliance (previous name- WECA). This organization is built with more than 200

registered business or companies whose nature of business is to examine and confirm the

interoperability of Wireless LAN items, to confirm that those products are based entirely

on the IEEE 802.11 stipulation. We also need to remember that WiFi items are

extensively dispersed, and an easy means of technology to utilize.

Main advantage is its data rate is very good comparing to 3G, as in 802.11b it is 11mbps

and in 3G it is only 2mbps.

License free Frequency band (2.4 GHz).

If we compare with Ethernet, Wi-Fi is having great mobility, because Wi-Fi is

wireless and Ethernet is wired.

The network is secure because of Wi-Fi is providing very good security, like

WAP, WAP2 etc.

In built power save mode in Access Point, to save the battery of Mobile Station.

As explained bit more in chapter 4.3. Having WMM power save mode.

WiFi uses unlicensed radio spectrum and does not require regulatory approval for

individual deployers.

It allows local area networks (LANs) to be setup with cabling. The can reduce

associated costs of network connection and expansions. Places where cables

cannot be run, such as outdoor areas and historical buildings can use wireless

LANs.

WiFi products are extensively available in the market. There are different brands

of access points and user's network interfaces are able to inter-operate at a very

basic service level.

Prices are considerably lower as competition amongst vendors' increases.

WiFi networks can support roaming. This allows mobile users with laptop

computer to be able to move from one access point to another.

Numerous access points and network interfaces support various degrees of

encryption to protect traffic from interception.

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WiFi has a set of global standards. Not like the cellular carriers, the same WiFi

users can work in different countries around the world at all time.

2.10.2 Disadvantages:

Though the WiFi products currently available on the market are very useful, of course

there are still few collapse which must be affirmed in turn to gain a steady clutch on

precisely what the WiFi wireless LAN expertise are self-possessed of. As per Mr. Morely

points out, "Wi-Fi is designed for medium-range data transfers, and most versions of

802.11 work up to about 250-300 feet away from the access point indoors, and about

1,000 feet away outdoors."(341) Being agree with this, and with further distance in

between one’s computer and/or a laptop and the AP (access point), the frequency plus the

quality wavers tremendously. It might not help if a interference from cordless phones or

any microwaves which can use the similar occurrence that 802.11g and 802.11b use: 2.4

GHz. One more crucial and noticeable disadvantage for WiFi items is their security

system. One of the latest security techniques in the market is WEP. If this Wired

Equivalent Privacy (WEP) somehow become the general standard of wireless encryption

which easily can be accessed and broken even when configured and secured precisely.

(Wikipedia, WiFi) To offset this issue, however, Wi-Fi Protected Access (WPA) has

been introduced in the market and taking over the previous faulty encryption system and

working well.

Operational limitations and the Spectrum assignments are not reliable everywhere in

world; most of the countries in the Europe allow for an extra two channels, anything

beyond those two legitimated in the States. Recently Japan has managed to get one more

innovation on top of that - and some other countries,as well. Those imcludes Spain can

forbid the operation of the lower-numbered channels in the WiFi settings. In addition

some other countries like Italy, requires a 'general authorization' for all Wi-Fi which can

be used outside of an vendor’s office premises, or asking something to an operator for

membership registration for a certain period of time or even for a year.

It has fairly high power consumption compared to some other WiFi standards, by making

battery life worsen and the concern for the extra heat generation.

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The most commonly used wireless encryption method, WEP (Wired Equivalent Privacy),

recently showed that WiFi can be breakable even though when it is correctly and securely

configured.

With the general settings, any Wi-Fi Access Points normally set to an “open mode”. New

users on a network can gain some benefits from a no-configuration device that operates

out of the package but will not concern to assign open wireless access on their Local Area

Network. As a new method- WPA Wi-Fi Protected Access has began to release in early

2003 aiming to resolve these issues and is commonly available, but acceptance rates is

still noticeably low than what was expected.

As per the factory settings- Wi-Fi networks configured with a limited scope. A common

Wi-Fi router for home use can be operating on 802.11b or 802.11g with a livestock Ariel

may have an acceptable range of 45 metres, on the line of sight (equivalent to 150 ft)

indoors and 90 m (300 ft) outdoors. These range may also varies with the channel band

available and set by the user, as Wi-Fi does not make an exception to the law of physics

of spectrum wave proliferation. Wi-Fi using the 2.4 GHz incidence chunk always got

better scope than a Wi-Fi which is set on the 5 GHz frequency chunk, and less range than

the oldest Wi-Fi (and pre-Wi-Fi) 900 MHz block. And also the outdoor range with better

and empowered antennas can be quite a few kilometres or even this can be more while

staying on the line-of-sight.

Pollution of Wi-Fi, which means meddling a stopped up or encrypted access point with

another open access points which is in the same area, particularly if on the same or

adjacent channels, can avert the access and get in the way by the means of other open

access points by others uasers reason by the overlap of the 2 or more channels in the

802.11g/b frequency and also with reduced signal-to-noise ratio (SNR) between those

access points in the same area. This is a widely seen issue in highly rated areas like large

apartment building or complexes or office premises having several or more Wi-Fi APs

(Access Points).

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The Wi-Fi networks can be controlled and monitored and operated to translate and share

data (irrespective of personal information) sent over the open network while having no

encryption system in place, as a Virtual Private Network (VPN) is used.

Interoperability is also one of the issues between the brands or divergence from the

benchmark which can disturb the connections or reduce the expected throughput speeds

over other user's Laptops or PCs within the same range. Wi-Fi Alliance plans test devices

for the set interoperability standard and they designates the devices which can pass the

testing phase as Wi-Fi CERTIFIED.

Compare to 3G its mobility is very less, as 3G is having several kilometers and Wi-Fi’s

max 100 meters.

Compare to Ethernet its data rate is less as we can get speed up to 1gbps in Ethernet, and

in Wi-Fi 54mbps (802.11n)

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3.0 Research Methodology

3.1. Basic principle of energy consumption in wireless:

3.1.1 Power (Link) budget calculation for 3G:

Link (power) budget used to calculate losses in the signal strength between mobile station

antenna and base station antenna. These calculations are helpful to define cell range and

coverage thresholds. [3]

Basically link budget is done for both uplink and downlink calculations. Here mobile

station transmits less power compare to base station. That’s why uplink link budget is

more critical than the downlink link budget. In opposite downlink antenna requires more

power and gain. The cable loss has to be considering in both i.e. uplink and downlink. [3]

The (MS) mobile station transmitted power is more important than (BTS) base station.

Because mobile station runs on battery operated power supply and it is very less compare

to base station. [3]

A part of the network planning process is the Link budget planning, which in turn can

help to measurement the expected exposure, aptitude and excellence of the service

requirement in any given network. 3G worldwide mobile-cell coverage is limited to the

uplink, because the level of mobile power is also limited to (voice terminal: 125mW).

Downlink trend which limits the obtainable capacity of that cell. transmission power

(typically 20-40W) has to be divided to all users. On any given network surroundings

both the coverage and also capacity are connected by the interference produced by the

system. By enhancing one side of the calculation might reduce the other side. System is

insecurely steady by the factory design. The objective of the link budget design is to work

out the utmost cell dimension under the criteria given below:

Service types of the 3G (type of data and Data transfer speed)

Environment kind(terrain, building access)

Type and behaviour of mobile (reliance, maximum power consumption level)

configuration of the system (antennas of BTS standard, BTS power consumption,

signal loss on cable, gaining the handover)

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Probability of the required coverage

Economical factors and the Financial factors (the use of mostly costly and also the

better quality tools or of course not the cheapest set upsystem)

and also to match all of these to gain the required system coverage in the 3G area, ability

and quality needs with each area and the service offered be the 3G.

The capacity will be the limiting factor in a suburb area, so the internal city cells int he

city will be categorised by the expected Erlangs/km² for both of the voice and data

transmission. Irrespective of using 25dB as in a premises penetration can loss into the

organisation premises’ core region, link budget would normally accept about 300-metre

cell range, which is in a way too much for a capacity reason. In a suburban area uplink

power financial plan will find out the utmost cell range in a 3G area, while normally cells

are less crowded. A normal cell range in suburban areas might be several kilometers

depending on a terrain and on the line of sight.

An example of how 3G voice link budget can be done is given below. Few of those

parameters can be discussed, depending on the spread of the model, but also it can give

an image of the computation methods of the entire system.

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Figure 3.1: UMTS link budget

(Ref: http://www.umtsworld.com/technology/linkbudget.htm)

Now let us see some important components of power (Link) budget calculations

Mobile station (Ms) sensitivity: The sensitivity is highly depends on receiver noise

figure and Eb/No. we can calculate this by GSM specifications they recommends it 5.05.

The MS sensitivity is depends upon which class of mobile is being used. However we

have to use values given by manufacturer. [3]

Base station (BTS) sensitivity: it can be specified as same like MS sensitivity. The

recommended value is also same i.e. 5.05. However we have to use values given by

manufacturer. [3]

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Fade margin: it is diff between received signal & receiver threshold. Fast fade margin

is very good on power calculations. For different area we use different values like 2db for

dense urban and 1db for normal urban.[3]

Other losses (connector and cable): in both MS and BTS we use cables and connectors

for transmitting power. The losses occurred in them are very less but need to take in to

account. Normally we calculate cable loss in db per 100m. Typically connector loss Is

0.1db, which is very less.[3]

Antenna gain: the antenna use by MS is having very less gain compare to BTS

antenna. Because of MS battery capacity. The MS antenna gain has of the order 0dbi, and

BTS antenna gain may vary from 8dbi to 21dbi. We can increase gain of antenna by

various techniques like antenna diversity.[3]

Now let us take one example to calculate Power budget for uplink.

Base station: Mobile station:

Antenna gain is 18dBi Antenna gain is 0dBi

RF power is 42dBm RF power is 42dBm

BTS sensitivity is 108dBm MS sensitivity is 106dBm

Cable loss is 2dBm Cable loss is 0dBm

Figure 3.1: (BS & MS Uplink/Downlink link budget)

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PLu (Path loss in uplink) = ERIPm (Peak ERIP of Mobile) – Prb (power received by BS)

ERIPm= Ptm (Power transmitted from MS) – Losses + Gm

Losses= Lcm (cable loss at mobile) + Lom (any other loss)

Prb = -Gb (antenna gain) – Losses +Bs (Base sensitivity)

Losses= Lcb (cable loss at BTS) +Lob (any other loss)

PLu = EIRPm –Prb

= [Ptm-Lcm-Lom+Gm] – [-Gb+Lcb+Lob+Bs]

= [32-0+0+0]-[-18+2+0+(-108)]

= 32+124

= 156dB

Same way we can calculate for downlink power budget which comes 162db. [3]

Here we can see the difference between both uplink and downlink calculations result. The

downlink path loss is more than that of uplink path loss. It means that area covered by

base station is more than mobile station. [3].

Now let us consider WCDMA link budget calculation. We will consider only for uplink

link budget because it is most important for mobile station battery performance.

Example:

W-CDMA has various bearer services at various data rates. Like web browsing (delay

tolerant data service), file transfer with 384kb/s. In urban non-real-time it is 256kb/s at 3

to 10km/h. because at this rate the BER is very low.

Let us assume some parameters now, to calculate path loss in uplink.

Mobile station transmitter power = 24dBm

Penetration loss (in vehicle) = 8dBm

BS antenna gain=16dBm

BS cable loss (receiver) = 2dBm

Noise figure of receiver= 5dBm

Interference margin of receiver= 3dBm

Rb (information rate) =256kb/s

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Eb/No (signal to noise ratio) =6dB

Soft hand off margin =2dB

Fade margin =8dB

Body loss =2dB

Now

Power in to the base station is

Pin = 24- body loss- penetration loss-path loss +BTS antenna gain- cable loss

= 24-2-8-Pl+15-1

=28-Pl dBm

Noise and interference density of receiver= 5+3-174=-166dBm/Hz

We have fade margin, Eb/No and data rate 14.4kb/s, now we can calculate input signal as

Required input signal= -166+7+8+10log (256,000)

= -97.9

Soft handoff is 2dB

Therefore,

Required input signal= -97.9-2

=-99.9

Therefore

Pin ≥ -99.9dBm or

30- Pl ≥ -99.9

Pl ≤ 30+99.9

Path loss Pl= 129.9 dB

3.2 3G power control algorithm:

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In 3G there are two main factors determines energy consumption. One is transmission

energy which is proportional to power and length of transmission. Second one is RRC

(Radio resource control) Protocol. [1]

In 3G there are 3 types of main power control mechanisms as:

1. Open loop power control

2. Close loop power control

3. Adaptive-step power control

1. Open loop power control: It is the capability of mobile station to fix or set output

power to a specified value, which can be suitable for base station. This value can be

calculated depending upon measured path loss. The tolerance value can be chosen by

operator (for e.g. +/-9dB to +/-12dB).

This open loop power control consumes more power compare to others so that’s why it is

not in use. [5].

2. Close loop power control: It is the capability of mobile station to adjust power

according with TPC symbols receives by the Base station. It is based on measurements of

SIR (signal to interference ratio). This mechanism is done with feedback of both sides i.e.

MS and BS. If power is high through MS then BS send symbols to MS that power is high

then MS get understand and reduces its power and vice-versa. [5].

3. Adaptive-step power control: In WCDMA the transmitted power is more than 70dB.

In WCDMA variations occurs in mobile network because of communication starts and

ends, the movements of mobile and propagation channel changes. The modification of

Radio channel may be due to obstacles movements and multipath. For these reason we

need fast power control mechanism. [4].

The one power control command is send per time slot. The step value may be some time

small or some time to large to transmitted power requirement. Several simultaneous up

command detect by the transmitter, and then the step is increased. This can be done for

down command. The update can be decreased if alternative succession appears in down

and up. The algorithm is having many forms using this principle. [4].

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3.3. Wi-Fi power control algorithm:

Wi-Fi in build phones mostly uses Power save mode (PSM). The energy consumed to

transfer data is proportional to size and transmit power level. According to [1] the energy

consumed by Wi-Fi is less as compare to 3G for large size of data.

3.3.1. Wi-Fi power management:

The WMM (Wi-Fi Multimedia) is ideally designed for portable devices like mobile

phones, PDA etc which requires power save mechanism for battery to extend its life.

WMM is suited for VoIP, but in addition audio players, Laptops, game consoles, can also

get benefit from it. [2]

To integrate Wi-Fi in a mobile was a major challenge, and its impact on energy

consumption of battery life. To overcome this challenge Wi-Fi Alliance introduced

WMM power save technology.

The devices which are having strict latency requirements, for those devices the WMM

have been optimized. It offers more flexible and more efficient way to transmission

between client and AP. So not only battery life extended but performance also improves.

[2]

The WMM has application based approach. So WMM enables individual applications

how often mobile (client) want to communicate with AP. And how much time client will

be in dozing state. In the legacy power save the client remains in dozing state, regardless

which applications are active? The client may goes in more dozing state to save power,

but it degrades performance of applications. [2]

Compare to Legacy the WMM gives more befits, because the tighter control over the

transmission and good management between dozing and active mode gives more

flexibility to battery operated devices. [2]

The WMM power save technology depends upon MAC (Media Access Control) layer of

802.11. It is designed to contribute and support 802.11n group.

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3.3.2 How WMM Work?

WMM improves the efficiency by allowing client to keep more time in dozing and

decreasing number of frames that client need to receive and send. To download the

frames buffered by AP, it consist signaling mechanism. This enables AP to buffer frames

and pass to client as request come from client. [2]

Figure 3.2: (Voice traffic using WMM) [2]

The behaviour of WMM power save is negotiated with association of client and AP. The

legacy power cave or WMM set for all WMM AC transmit queue separately in queue.

The AP will send all data using either legacy or WMM power save. (Above figure shows

an idea).

When client uses legacy power saves, clients need to wait for beacon frame to download

data. But WMM can initiate download at any time, thus it allows more frequent data

transmission.

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Client does not require waiting for beacon frame to download from AP in the WMM. In

WMM AP buffers all voice data to deliver client until trigger frame is receive from client.

All the frames are transmitted at this point.

Figure 3.3: (VoIP in WMM) [2]

the client transmit uplink frame which act as trigger frame in 20ms and download frames

buffered and saved by AP. When download complete the client again gets in dozing

mode until next trigger frame comes. Thus overall client remains in dozing mode and

consume less power. [2].

3.4. Different Parameters in 3G and Wi-Fi:

To compare the 3G and Wi-Fi properly we have to consider first some parameters then it

will be very easy to find out which network is more energy efficient. Basically both

technologies are good in their own requirements and so on. So it is very difficult to say

which one is more energy efficient. Let us have looked some important parameters.

Here is one table which gives an idea of both technologies specifications.

Parameters 3G Wi-Fi (IEEE802.11b) References

Carrier Frequency 1800-2100 MHz 2.4-2.497 GHz [8], [9]

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Modulation QPSK DSSS (CCK) [8], [9]

Data rate 2 Mbps 11 Mbps [8], [9]

Range Several km 38-125 meters [8], [9]

Bandwidth 15-20 MHz 20 MHz [8], [9]

Energy per 50K 2.3 Joules 0.92 Joules [1]

Simultaneous Users (Clients) Several thousand 20-30 [9]

Hardware parameters used in Client (MS)

IC ADF4602 IC SG901-1028

Supply Voltage 3.3 to 3.6 Volt 3.3 Volt [6], [7]

Supply Current Rx =50mA

Tx =100mA

Rx =253mA

Tx =520mA

[6], [7]

O/P impedance 50Ω NA [6], [7]

I/P impedance 100Ω NA [6], [7]

O/P Power -8dBm 12dBm [6], [7]

Table3.1: (Parameters of 3G and Wi-Fi)

3.5. Parameters of Energy consumption

BER

Eb/No

Protocol overhead

Circuit Implementation

BER (Bit error rate):

The BER measures the quantity of reliability of the radio system. It measures the bits in

and bits out.

The simple definition of BER is error divide by total number of bits as shown below

BER= Errors/ Total number of Bits.

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Ideally BER should be zero. But practically it is not possible. To reduce the BER we can

use amplifiers, filters, mixers and ADC/DAC.

Factors affecting BER:

The main factor causes the BER is noise e.g. white noise, thermal noise etc. To reduce

BER reduce spectral noise density by reducing bandwidth. But we can’t reduce

bandwidth as Nyquist criteria to transmit the desired bit rate.

Another way is increase the energy per bit but it may cause interference with other

systems. Ultimately we have to optimize Eb/No which balance all this factors. [16].

Eb/No:

Eb/No is defined as ratio of Energy per bit (Eb) to the Spectral Noise Density (No).

Actually this ratio measures the signal to noise ratio in digital communication system.

Basically it is measures at i/p of receiver, and can say how much strong signal is.

For different types of modulations like QPSK, QAM, BPSK etc, have different types of

curves of BER vs. Eb/No. Here are some theoretical vales for different modulation

schemes, with RF power given. [17].

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Figure 3.4: (Eb/No vs. BER) [17].

Protocol overhead: The overhead is nothing but adding bits to datagram’s to enable

delivery to the destination. Since few data required sending for routing the information

message, this additional protocol data is referred as overhead. Because it does not

contribute message information data, it reduces the efficiency of the network, so we can

say it to as network overhead as well. It consumes some bandwidth of information data,

so it should be minimize to get full sufficient network. Theoretically it should be 0% to

achieve 100% efficient network. But practically it is not possible. So let us see the

theoretical graph of protocol overhead vs. talk time, because we are discussing about

mobile battery energy efficiency.

Figure 3.5: (Protocol overhead vs. talk time)

Circuit implementation: The circuit implementation is always measures in

percentage, as it is related to circuit/hardware. There are always having some errors in

hardware devices like mobile phones, laptop etc. This errors or losses in circuit can be in

the form of heat energy while devices are being used, as we know that while talking on

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mobile, it generates heat. This heat is actually loss of energy. This heat produces in the

hardware like IC’s, resistors, capacitors and inductors.

Still any circuit or device is not 100% efficient. Practically there will be some losses. But

theoretically it supposes to be 100% otherwise we lose some energy and ultimately

efficiency of circuit reduces. Let us see now theoretical graph of circuit implementation

in percentage vs talk time of mobile phones in percentage.

Mobile Internet gate nowadays is moderating the irritation of fame. The ubiquitous

exploitation of mobile data networks has strained millions of subscribers to these cellular

networks, which is in go to creating enormous pressure on the restricted range of these

systems. Subscribers, particularly in large cities, are practicing fading 3G quality for the

reason that the network cannot manage with the high-pitched order. In response to this

stress, wireless operators are using systems such as striking a boundary of 5GB per

month and cultivating" their subscribers on \dependable" admission. We consider that

such systems are in the last part of ine_ective or at least insouciant. They are in

opposition the flood of subscribes' desire for better utilization. We examine the feasibility

of a deferent system| enlarging 3G utilizing WiFi. That is, minimize the force on 3G

range by utilization WiFi connectivity when workable for transmitting data.

At least one-wireless operator is opening reasons to its users to minimize their 3G control

by replacing to WiFi at living place. In supplement to minimizing force on 3G range,

such increases also minimize the per-byte outlay of data transfers, by 70 % per one

approximation. In this thesis, I cover on vehicular Internet admittance, an acutely

demanding case for cellular connectivity. A raising amount of subscribers nowadays

browse the Internet from travelling means of transportation, either straight from side to

side their individual devices or from side to side proxies within transit means of

transportation. A spectrum of other devices, such as routing units, also requires such

connectivity. Though, utilizing WiFi networks from moving means of transportation is

challenging. WiFi APs contain a minimal spectrum and are usually not organized to

supply exposures to roads. Still when APs are in spectrum, the excellence of connectivity

may be reduced. Therefore, it is uncertain if WiFi can helpfully supplement 3G, while

supplying the ubiquity and dependability that 3G users be expecting.

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To recognize feasibility, I perform a explained study of common 3G and WiFi access

from moving means of transportation, in three dissimilar cities. We end that on standard

3G access is accessible 87% of the point in time, as the same time as WiFi access

(through open APs) is free only 11% of the point in time. Even though we don’t identify

why, our data recommends that the common accessibility is in the negative connected. In

spaces where 3G is not available, WiFi is accessible about half the time. As a result, the

arrangement is more accessible than if the two had autonomous accessibilities. On the

other hand, we also end that in half of the places where WiFi is accessible; its throughput

is more less than 3G. WiFi as well skills a higher loss cost. To our information, our

occupation is the rest joint classification of 3G and WiFi; past works have calculated the

presentation of one or the others. Our learning as a result recommends that simple

system to join the two will minimize 3G charge by at the majority 11%, and still that will

approach at the expenditure of indigent application presentation. We design a system

called Wifi to defeat this availability and presentation opposes. Its two important ideas

are leveraging postpone tolerance and fast exchanging to 3G. We survey that most

applications for example electronic mail or transfer can aboard to postpone data transmits

exclusive of significantly smarting user practice.

Wifi influences this reservation to trade-o upper application latency for minor 3G utilize.

As an alternative of transmitting data without delay, it delays for WiFi to become

accessible. By utilizing an easy system to forecast upcoming WiFi throughput, it delays

simply if 3G reserves are predictable under the application's waits acceptance. Moreover,

so that the presentation of waits and loss receptive applications isn’t hurt, Wifi quickly

exchangeses to 3G, if WiFi is not able to broadcast the packet in a time window.

We execute and organize Wifi on a vehicular test bed. We assess Wifi utilizing the

exploitation and utilizing trace motivated simulations. In our exploitation, we

experimented that for transports of size 5MB that know how to be delayed by at majority

of 60 seconds, Wifi minimizes 3G usage by 30%. In replication utilizing practical

workloads, we find that Wifi minimizes 3G usage 45% for a 60 seconds delay

acceptance. For the reason that of its wait only-if-it-helps stratagem, the real transmit

latency is raised by simply 7 second on standard. In favor of a VoIP application, we find

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that the point in time periods with excellent VoIP quality rises by 31% (complete

improvement) utilizing fast exchanging compared to a method that exchanges to WiFi

irrespective of its standard quality. More significantly, the rise in quality is attained yet

when 40% of the VoIP trance was forwarded over WiFi.

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4.0 Evolution

4.1 3G vs. Wi-Fi:

Here we are going to compare these two technologies i.e. 3G and Wi-Fi, in terms of

energy only.

4.1.1 Algorithm to find out the battery consumption in mobile device: To find out the

power consumption we have to fallow some steps. If we fallow these steps one by one

then it is very easy to say which network consumes more energy and which is more

efficient.

First decide how much number of bits we are going to transfer.

Then decide how much time we are going to transfer.

Then determine (Assume) some parameters like circuit implementation, network/Protocol

overhead, BER and Eb/No. (these parameters depends upon modulation scheme like 3G

is having QPSK, and Wi-Fi 802.11b is having DSSS-CCK )

After that find out the energy require to transfer in joules.

Calculate current with the help of power formula P=I*V

Once we got energy per bit per second we can find out for different time interval and for

different data rate.

Now from above algorithm we will concentrate on energy consumption in 3G and Wi-Fi.

To transfer 50kB data on both networks i.e. 3G and Wi-Fi we need 2.3 Joules and 0.92

Joules respectively. These values are taken average, by taking more than 50 trials. [1]

50kByte= 50,000*8 bits

= 400000 bits

Form above we can calculate energy for 1 bit.

Average transfer energy for 3G = 0.00000575 Joules/Bit =5.75mW

Average transfer energy for Wi-Fi = 0.0000023 Joules/Bit =2.3mW

According to above values of energy consumption in 1 Bit, we can calculate for different

Bits intervals as shown in table below.

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Here we have assumed some parameters as (From Chapter 4)

Network/Protocol overhead is 15%

Circuit implementation is 95%

Eb/No ratio is 7dB

Data rate in Kbits/sec Energy in Joules for 3G Energy in Joules for Wi-Fi

2.5k 0.014 0.00575

5.k 0.028 0.0115

7.5k 0.0431 0.0172

10k 0.0575 0.023

12.5k 0.0718 0.028

15k 0.086 0.034

17.5k 0.100 0.040

20k 0.115 0.046

22.5k 0.129 0.051

25k 0.143 0.0575

Table 4.1 (Energy requires for 3G and Wi-Fi for different Bits)

Above values and graph is about only energy in joules now let us compares these

technologies in watt. For this we will take one cellular mobile phone and calculate energy

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in Watt per second. And that will be same, i.e. in watt.

So now we have power, and by assuming voltage as 3.3 volt (for mobile phone) we can

easily calculate current as

P=I * V

Therefore,

I=P/V

From this formula, below table is made for Current Consumed by 3G and Wi-Fi for

different Data rates.

Data rate

In kbps

Current in mA

for 3G

Current in mA

For Wi-Fi

2.5k 0.0042 0.017

5k 0.028 0.0115

7.5k 0.0431 0.0172

10k 0.0575 0.023

12.5k 0.0718 0.028

15k 0.086 0.034

17.5k 0.100 0.040

20k 0.115 0.046

22.5k 0.129 0.051

25k 0.143 0.0575

Table 4.2 (Current requires for 3G and Wi-Fi for different Data rates)

4.2 Voice communication over 3G and Wi-Fi:

Suppose we are having mobile phone with inbuilt 3G and Wi-Fi. So we can make call

from 3G by dialing mobile number or we can make call from SKYPE with Wi-Fi

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network. And mobile is running out of battery, and cannot able to recharge it soon. In this

condition if we want to make an emergency call, then here comes problem. Which

network we are going to choose? So we can able to use more talk time or battery will be

long last.

For this question we have to find out energy for voice communication. And for voice

communication we know that data rate is almost 56kbps for 3G and Wi-Fi.

Assume battery voltage of mobile is 3.3 volt and Current 1500mA/hour.

Before finding result let us understands about Li-ion battery and how it gets discharge.

Charging and discharging current is measured in C-rate. Most of batteries are rated by

1C. This means 1000mAh battery can provide 1000mA for an hour if we discharged by

1C rate. If we discharged with 0.5C i.e. with 500mA would provide 2 hours. Same way if

we discharged with 2C, battery provides 2000mA current for half hour only. From above

discussion we can say that 1C referred as 1hour, 0.5 referred as 2 hour and so on. Now

day’s mobile batteries are having capacity of 1500mAh delivery of current. It means they

give 1500mA of current in one hour and rate is 1.5C. [15].

We know energy for 25k for both 3G and Wi-Fi, as 0.014Watt & 0.00575Watt.

Now let us calculate for 56kbps

For 3G (in 1 second)

Energy= 0.322mWatt

Current= 0.09mAmp

For Wi-Fi (in 1 second)

Energy= 0.12Watt

Current= 0.039mAmp

Now we got both values i.e. Energy and Current in one second. So we can easily

calculate for minute multiplying by 60. Already we know constant voltage as 3.3volt.

From these values we can calculate Energy and Current for different talk time as,

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Talk time

In min

3G Network Wi-Fi Network

Energy in mW Current in mA Energy in mW Current in mA

15 min 126 36 52.2 15.3

30 min 252 72 104.4 30.6

45 min 378 108 156.6 45.9

60 min 504 144 208.8 61.2

Table 4.3: (Energy & Current require for 3G and Wi-Fi while talking with 56kbps data

rate)

From above table the graph will be as below shown.

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From the graph of Energy vs talk time for mobile phone we can easily justify that 3G

network consume more battery compare to Wi-Fi. So now it is clear that better to go for

Wi-Fi when battery is running out of power. The reason behind this is as:

Wi-Fi is having more data rate as 11Mbps compare to 3G’s only 2Mbps.

By Wi-Fi we can transmit bigger size of packets, so Protocol overhead is good

compare to 3G.

The path loss (Pl) is very less in Wi-Fi as compare to 3G, as AP is near to MS.

Now we discussed for energy consumption in 3G and Wi-Fi. And got to comes to know

that Wi-Fi is more energy efficient than 3G. But in some manner 3G is good so let us

have look :

Coverage area is very good as several kilometers as Wi-Fi is having only few

hundred meters (mostly less than 100m).

The mobility is very good than Wi-Fi.

From above two points it is clear that we will not be always in Wi-Fi coverage area. So if

we are not in Wi-Fi range then there is no choice of network choosing. Ultimately we

have to use 3G network.

4.3 Flow Chart:

Now let us make a flow chart for these all scenario.

The first generation(1G) wireless network was analogue. The earliest in North America

was advanced mobile phone system(AMPS), which was established on frequency

category multiple right of entry. A complete of 1664 channels was presented in the

824MHz to 849MHz and 869MHz to 894MHz band, given that 832downlink (DL) and

832uplink (UL)channels. AMPS, extensively utilized in North America, supports

frequency reprocess. The fundamental network is a mobile network where a geological

region is separated into cells. A center station(BS) at the center of the cell transfers

signals to and as of users surrounded by the cell.

The second generation (2G) methods on are digital. Digital methods turn out probable an

array of latest services for example caller ID. The Global System for Mobile

Communications (GSM) is a famous 2G system. GSM suggests a data rate of 9.6kpbs -

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14.4kbps. It supports worldwide roaming, which stands for users may contain right to use

wireless services still when roaming abroad. The most famous service suggested by The

Global System for Mobile Communications (GSM) is the Short Message Service (SMS),

which permits subscribers to send off text messages up to 160characters lengthy.

2.5G methods care for more than only voice communications. In extra to text messaging,

2.5 G methods suggest a data speed on the sort of 100 kbps to support a variety of data

technologies, as for example Internet access. The majority 2.5G methods implement

packet exchanging. The 2.5G methods help present seamless evolution technology

relating 2G and third generation (3G) methods. The next are 2.5G methods:

High Speed-Circuit Switched Data (HSCSD): Still though majority of 2.5G systems

execute packet switching, HSCSD goes on with support for circuit switched data. It

presents a data speed of 115kbps and is intended to improve The Global System for

Mobile Communications (GSM) networks. The access technology utilized is point in

time division multiple-access (TDMA). It presents support for Web surfing and file

moves.

General Packet Radio Service (GPRS): GPRS proffers a data speed of 168kbps. It

improves the presentation and transmission rates of The Global System for Mobile

Communications (GSM). GPRS presents always on connectivity, which stands for

subscribers don’t have to connect again to the network for each and every transmission.

For the reason that there is a greatest of eight slots to transfers calls on one-device, it

permits in excess of one transmission at one point of time; such as, a verbal voice call and

incoming text message can be controlled at the same time.

Enhanced Data Rates for GSM Evolution(EDGE): EDGE works in combination with

General Pocket radio Service(GPRS) and Time Division Multiple Access (TDMA) over

the Global System for Mobile Communications(GSM) networks. Its presented data speed

is 384kbps. EDGE supports data exchanges as the same time as verbal voice

transmissions are supported utilizing the technology on presented networks.

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Third-generation (3G) wireless systems are intended to support high bit speed

telecommunications. 3G methods are intended to meet the necessities of multimedia

applications and Internet assistance. The bit speed presents spectrums from 144kbps for

whole mobility applications, 384kbps for restricted mobility applications in macro and

micro-cellular surroundings, and 2Mbps for low mobility applications in micro and Pico-

cellular surroundings. A very helpful service presented by 3G method is an urgent

situation service with the capability to recognize a subscriber's location surrounded by

125 m 67% of point in time. Figure 1.1 shows the evolution of wireless standards.

Evolution of wireless standards

Primarily, the International Telecommunication Union (ITU) decided to design a single

3G set; on the other hand, due to a amount of complexities, it has authorized two 3G sets.

The two sets are Code Division Multiple Access 2000(CDMA2000), which presents a bit

speed of up to 2.4Mbps, and wideband Code Division Multiple Access(WCDMA), which

presents a bit speed of up to 8Mbps. The maximum bit rate allows new wireless services

with the intention of can be organized into three categories:

Information retrieval: It allows location aware applications to distantly download

information from a mutual database.

Mobile commerce: It permits users to book a flight or pay bills.

General communication: It allows users to make or receive phone calls, transmits

messages, or activates an air conditioner at home.

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Multiple wireless services enable users to join dissimilar types of services to perform

specialized meanings. Such as, you can take a photo utilizing a camera phone and

forward it to a friend utilizing the multimedia message service(MMS). A majority of

useful application possible to join a home alarm method with a wireless method so that at

what time an interloper is recognized, a photo of interloper is snapped by the observation

camera and sent to the the system, at the same time the owner is aware via cellular phone.

A multiple service includes a basic wireless service (one that can’t be partitioned into

slighter identifiable services), a utility service (one that carries out a system surrounded

by a particular multiple service series), and probably another complex service. Such as,

be concerned about a courier service driver who has to hand over a document before a

certain cut off date and he has to locate the speedy and minimum crowded way to its

target receiver. It creates use of a way preparation application on the wireless workstation

in the driver’s van, which holds of three basic wireless services:

A position service to find out the present position of the driver.

A roaming way totalling to find out the minimum crowded and speedy way to the

drivers destination.

Traffic knowledge rescue to gain traffic knowledge through different sources.

The Complex service made up of nonstop repetition of those services: find out the present

position and present it to the wireless workstation, calculate the minimum crowded way

from the present position to the target receiving host, and read the most up to date

network traffic knowledge. It engages using step 1 and make a decision whether to iterate

step 2 and then leaving back to step1 which is the facility service.

Cellular computing is an energetic arena of research and developments. Majority of the

applications can be found by the users nowadays are aimed at young and others and are

mainly sophisticated computer applications, such as, downloading the music files, finding

new friends, and also getting the latest updates. It may possibly be some majority of point

in time prior to the mobile communicating application software that emerges in the

market as if there are so many concerns which requires to be locating to effectively and

efficiently produce such similar applications. Because, many of the examples explained

in this thesis are based on ongoing and experimental research. Therefore, a list of

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references, bibliographies, and online resources are provided at the end of the chapter so

that readers may further explore the topic.

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Chapter 5: Conclusions

5.1 Conclusion:

From chapter 5th it is clear that Wi-Fi is more energy efficient, i.e.3G consumes more

power than Wi-Fi. As from graph 5.2 the energy requires for 3G and Wi-Fi for different

intervals are plotted.

So whenever there is Wi-Fi network available better to switch or choose Wi-Fi. As some

time the condition may occurs that battery is running out off, and that time only some

emergency call comes or maybe we only need to call. For example we need to call boss

or our business partner that time if we know that 3G will be going to consume more

battery, and then we can take correct decision, and can switch to Wi-Fi network.

As we know that Wi-Fi is having more data rate as compare to 3G. As well as its Access

point (AP) is very near to mobile station (MS) as compare to 3G base station (BS),

ultimately it requires very less path loss as compare to 3G.

5.2 Future Work:

It is very interesting topic to research furthermore. As In the future we can:

Design of these two technologies i.e. 3G and Wi-Fi with the help of NS-2 or Opnet

modulator 15.0 to check the energy efficiency and performance criteria, and we can

compare these two technologies in deep or we can say in practically.

Design of these two technologies using NS-2 or Opnet modulator to check for different

applications like VoIP e.g. Skype, Video conferencing, data transfer etc to check the

energy efficiency during these process.

5.3. Energy saving techniques:

Usually, mobile phone batteries drain out exactly when we want them the most.

However, there are a few things that can be done in order to make you get that last mile

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from your battery before it drains out completely.

Normally mobile phone batteries get drain if we don’t use it properly. Usually number of

people doesn’t have any idea about battery saving techniques. Here are some techniques

or an idea to save your mobile batteries.

As from chapter 5 we got comes to know 3G consumes more batteries than Wi-Fi. So if

you’re mobile is having both technologies and u want to use internet and ur in the range

of Wi-Fi then try to use Wi-Fi. It will save your battery as well u can get good speed of

data rate as well.

Make sure that your infrared and BLUETOOTH is always switched off when

your not using them. Because they always keep drawing power for signals.

You can make the vibrating alert OFF, when you are not using them for example

in home we don’t need of vibrating alert.

By readjusting your mobile screen brightness to 50%, we can save up to 50%

power from which screen use to consume.

By readjusting back light to required time can also help to save battery.

We can save battery by making desired sound for ringing & message tones from

sound profile setting.

Some time while playing game we use to use sound and vibrating mode ON,

which is not require for few games. So we can make them OFF and save some

battery.

Last but not in list is, try to recharge battery before it gets totally drain or empty, as well

as don’t recharge for long time it may reduce battery life.

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References:

[1] N. Balasubramanian, A. Balasubramanian, A. Venkataramani, 2009, Energy

Consumption in Mobile Phones: A Measurement Study and Implications for Network

Applications, ACM, PP. 280-293. (Accessed on : 05/11/2010)

[2] Wi-Fi Alliance ,WMM™ Power Save for Mobile and Portable Wi-Fi® CERTIFIED

Devices, December 2005. (Accessed on : 05/11/2010)

[3] A. R. Mishra, Fundamentals of Cellular Network Planning and Optimization

2G/2.5G/3G Evolution to 4G, 2004. (Accessed on : 05/11/2010)

[4] L Nuaymi, X. Lagrange, P. Godlewski, A Power Control Algorithm for 3G WCDMA

System. (Accessed on : 07/11/2010)

[5] http://www.3gpp.org/ftp/tsg_ran/wg4_radio/TSGR4_06/Docs/Pdfs/r4-99362.pdf

[accessed at 5th aug 2010] (Accessed on : 07/11/2010)

[6] Analog Devices, Single-Chip, Multiband 3G Femtocell Transceiver, ADF4602.

[7] Sagrad, SG901-1028 Miniature Wi-Fi Radio. (Accessed on : 05/11/2010)

[8] M.R. Karim, M. Sarraf, W-CDMA and cdma2000 for 3G MOBILE NETWORKS,

McGraw- Hill TELECOM, (Accessed on : 08/11/2010)

[9] J. Reynolds, Going Wi-Fi A Practical Guide To Planning And Building An 802.11

Network, Cmp Books, 2003. (Accessed on : 09/11/2010)

[10] http://itunes.apple.com/us/app/battery-life/id326103446?mt=8 [Accessed 18th

September 2010] (Accessed on : 05/11/2010)

[11] http://skypilot.trilliantinc.com/pdf/software/lb_4.9.pdf [Accessed 5th August 2010]

[12] M. S. Gast 802.11 Wireless Networks: The Definitive Guide, 2nd Edition, O’Reilly

(2005). PP: 19-22,122-126,136. (Accessed on : 12/11/2010)

[13] H. Honkasalo, Nokia, Wcdma And Wlan For 3g And Beyond. Ieee Wireless

Communications April 2002. (Accessed on : 15/11/2010)

[14] J. Korhonen, Introduction to 3G mobile communications, 2nd edition, Artech House,

2003. (Accessed on : 25/11/2010)

[15] http://www.batteryuniversity.com/partone-16.htm [accessed 16th August 2010].

[16] G. Breed (Editorial Director), 2003, Bit error rate: Fundamental concepts and

measurements Issues, High Frequency Design. (Accessed on : 05/12/2010)

[17] http://www.sss-mag.com/ebn0.html (Accessed on : 05/08/2010)

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[18] J. P. Wedge, 2001, Bandwidth Requirements For The Advanced Amphibious

Assault Vehicle (Aaav) Command Variant, Naval Postgraduate School, Monterey,

California. (Accessed on : 08/12/2010)

[19] http://www.networktutorials.info/mobile_technology.html (Accessed on : 2/12/2010)

[20] http://www.ehow.com/about_6319616_introduction-3g-mobile-communication.html

(Accessed on : 12/11/2010)

[21]http://rresearch.microsoft.com/pubs/135671/mobisys2010-wiffler.pdf (Accessed on :

09/12/2010)

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Appendices

Appendix1. Gantt chart

Figure: A2 (Gantt chart for project schedule)

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Appendix 3 List of Figure:

Figure1.1: (An idea about battery consume by Mobile “iphone” For all applications) [10]

Figure2.1: (Evolution of 3G) [13].....................................................................................12

Figure3.1: (IEEE 802 family and its OSI model) [12]......................................................16

Figure 3.2 :( 802.11 LAN’s Components) [12]................................................................16

Figure 3.3: (Passive scanning) [12]..................................................................................18

Figure3.4: (Active scanning) [12] ....................................................................................19

Figure 4.1: (BS & MS Uplink/Downlink link budget).................................................... 22

Figure 4.2: (Voice traffic using WMM) [2]......................................................................27

Figure 4.3: (VoIP in WMM) [2] ......................................................................................28

Figure 4.4: (Eb/No vs. BER) [17] .....................................................................................30

Figure 4.5: (Protocol overhead vs. talk time) ..................................................................31

Figure 4.6: (circuit implementation vs. talk time in %) ...................................................32

Figure 5.1: (Energy vs. Data rate for 3G and Wi-Fi)....................................................... 35

Figure 5.2: (Energy vs. talk time for mobile phone).........................................................38

Figure5.3: (Flow chart for choosing)................................................................................39

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Appendix 3 List of Table:

Table 2.1: (Features of W-CDMA and cdma2000) [8] ..............................................12, 13

Table 3.1: (Evolution of Wi-Fi)........................................................................................15

Table3.1: (Parameters of 3G and Wi-Fi)..........................................................................29

Table 5.1 (Energy requires for 3G and Wi-Fi for different Bits)......................................34

Table 5.2 (Current requires for 3G and Wi-Fi for different Data rates)...........................36

Table 5.3: (Energy & Current require for 3G and Wi-Fi while talking with 56kbps data

rate)...................................................................................................................................37

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