Lesson 1

Dr. Tahseen Al-DooriDr. Tahseen Al-Doori

Lesson 1Lesson 1

Overview of Wireless Standards and Overview of Wireless Standards and OrganizationsOrganizations


ObjectivesObjectives

In this lesson we will learn:In this lesson we will learn:

Standards OrganizationsStandards Organizations Communication fundamentalsCommunication fundamentals


Learning a new technology can seem like a Learning a new technology can seem like a daunting task.daunting task.

One of the keys to learning new subject is to One of the keys to learning new subject is to learn the basics.learn the basics.

Eg. Car, Airplane or Wireless network.Eg. Car, Airplane or Wireless network.


Identifying Standards OrganizationsIdentifying Standards Organizations

ITU-R: The International Telecommunication ITU-R: The International Telecommunication Union Radio communication SectorUnion Radio communication Sector

FCC: Federal Communications Commission.FCC: Federal Communications Commission. IEEE: The Institution of Electrical and IEEE: The Institution of Electrical and

Electronic Engineers.Electronic Engineers. Wi-Fi Alliance: Wi-Fi Alliance: ISO: The International Organization for ISO: The International Organization for

Standardization.Standardization.


ITU-RITU-R A global hierarchy exists for management of the A global hierarchy exists for management of the

RF spectrum worldwide.RF spectrum worldwide. ITU-R maintain a database of worldwide frequency ITU-R maintain a database of worldwide frequency

assignments and coordinates spectrum assignments and coordinates spectrum management through five administrative regions.management through five administrative regions.

Region A: North and South America.Region A: North and South America. Region B: Western Europe.Region B: Western Europe. Region C: Eastern Europe and North Asia.Region C: Eastern Europe and North Asia. Region D: Africa.Region D: Africa. Region E: Asia and Australasia.Region E: Asia and Australasia.


FCCFCC

Set the rules for what the user can do with a Set the rules for what the user can do with a radio transmitter. radio transmitter.

Frequency, power levels, and transmission Frequency, power levels, and transmission methods are managed and regulated by the methods are managed and regulated by the FCCFCC

It help to guide the growth and expansion It help to guide the growth and expansion that is being demanded by wireless users.that is being demanded by wireless users.


FCCFCC

The FCC and the respective controlling The FCC and the respective controlling agencies in the other countries typically agencies in the other countries typically regulate two categories of wireless regulate two categories of wireless communications: communications:

licensed and unlicensed. licensed and unlicensed. Licensed or unlicensed users are regulated Licensed or unlicensed users are regulated

on what they can do.on what they can do.


FCCFCC

Both licensed and unlicensed communications Both licensed and unlicensed communications are regulated in the following 5 areas:are regulated in the following 5 areas:

FrequencyFrequency BandwidthBandwidth Maximum power of the intentional radiatorMaximum power of the intentional radiator Maximum equivalent isotropically radiated Maximum equivalent isotropically radiated

power (EIRP).power (EIRP). Use (indoor and/or outdoor)Use (indoor and/or outdoor)


IEEEIEEE

The IEEE is probably best known for its LAN The IEEE is probably best known for its LAN standards, the IEEE 802 project.standards, the IEEE 802 project.

IEEE projects are subdivided into working IEEE projects are subdivided into working groups to develop standards for specific groups to develop standards for specific problems or needs.problems or needs.

802.3 for Ethernet802.3 for Ethernet 802.11 for Wireless802.11 for Wireless 802.11 subdivided into 802.11a,b,g,n…..802.11 subdivided into 802.11a,b,g,n…..


Wi-Fi AllianceWi-Fi Alliance

Wi-Fi Alliance is nonprofit association.Wi-Fi Alliance is nonprofit association. Devoted to promoting the growth of wireless Devoted to promoting the growth of wireless

LAN (WLAN).LAN (WLAN). It’s primary tasks is to ensure the It’s primary tasks is to ensure the

interoperability of WLAN products by interoperability of WLAN products by providing certification testing.providing certification testing.


Wi-Fi AllianceWi-Fi AllianceCertification include three categories:Certification include three categories: Wi-Fi products based on IEEE radio standards Wi-Fi products based on IEEE radio standards

802.11a, 802.11b, 802.11g in single mode, dual 802.11a, 802.11b, 802.11g in single mode, dual mode (b and g), and multiband (2.4 and 5 GHz) mode (b and g), and multiband (2.4 and 5 GHz) products.products.

Wi-Fi wireless network security, Wi-Fi protected Wi-Fi wireless network security, Wi-Fi protected Access (WPA), Personal and Enterprise; Wi-Fi Access (WPA), Personal and Enterprise; Wi-Fi protected access 2 (WPA2), personal and protected access 2 (WPA2), personal and enterprise.enterprise.

Support for media content over Wi-Fi network Wi-Support for media content over Wi-Fi network Wi-Fi Multimedia (WMM)Fi Multimedia (WMM)


ISOISO

It is a global nongovernmental organization It is a global nongovernmental organization that identifies business, government, and that identifies business, government, and society needs and develops standards in society needs and develops standards in partnership with the sectors that will put partnership with the sectors that will put them to use.them to use.

It is responsible for the creation of the It is responsible for the creation of the famous Open Systems Interconnection famous Open Systems Interconnection (OSI) model.(OSI) model.


ISOISO

The OSI model is the cornerstone of data The OSI model is the cornerstone of data communications, and learning to understand communications, and learning to understand it, is one of the most important and it, is one of the most important and fundamental tasks a person in the fundamental tasks a person in the networking industry can undertake.networking industry can undertake.

You should read more on OSI Model You should read more on OSI Model


Communications FundamentalsCommunications Fundamentals

We will review some fundamental We will review some fundamental communications principles that directly or communications principles that directly or indirectly relate to the wireless indirectly relate to the wireless communications.communications.

To understand what is happening with To understand what is happening with wireless communications you need to wireless communications you need to understand these fundamentals.understand these fundamentals.


Understanding Carrier SignalsUnderstanding Carrier Signals

Since data consists of bits, the transmitter Since data consists of bits, the transmitter needs a way of sending both 0s and 1s to needs a way of sending both 0s and 1s to transmit data from one location to another.transmit data from one location to another.

AC or DC signal by itself can NOT perform AC or DC signal by itself can NOT perform this task. this task.

If the signal is fluctuated or altered, then the If the signal is fluctuated or altered, then the data can be properly sent and received.data can be properly sent and received.

This modulated signal is know as Carrier This modulated signal is know as Carrier Signal.Signal.


Three components of a wave that can be Three components of a wave that can be fluctuated or modified to create a carrier fluctuated or modified to create a carrier signal are:signal are:

AmplitudeAmplitude Frequency andFrequency and PhasePhase


Amplitude and WavelengthAmplitude and Wavelength

RF communication starts when radio waves RF communication starts when radio waves are generated from an RF transmitter and are generated from an RF transmitter and sent to a receiver at another location. sent to a receiver at another location.

RF waves are similar to the waves that you RF waves are similar to the waves that you see in an ocean or lake. see in an ocean or lake.

Waves are made up of two main Waves are made up of two main components: wavelength and amplitude components: wavelength and amplitude


The wavelength and amplitude of a The wavelength and amplitude of a wavewave


WavelengthWavelength is the distance between similar is the distance between similar points on two back-to-back waves. When points on two back-to-back waves. When measuring a wave, the wavelength is measuring a wave, the wavelength is typically measured from the peak of a wave typically measured from the peak of a wave to the peak of the next wave. Amplitude and to the peak of the next wave. Amplitude and wavelength are both properties of waves.wavelength are both properties of waves.


FrequencyFrequency

FrequencyFrequency describes a behavior of waves. describes a behavior of waves. Waves travel away from the source that Waves travel away from the source that generates them. generates them.

How fast the waves travel, or more How fast the waves travel, or more specifically, how many waves are generated specifically, how many waves are generated over a 1-second period of time, is known as over a 1-second period of time, is known as frequency. frequency.


PhasePhase

PhasePhase is a relative term. is a relative term. It is the relationship between two waves with It is the relationship between two waves with

the same frequency. the same frequency. To determine phase, a wavelength is To determine phase, a wavelength is

divided into 360 pieces referred to as divided into 360 pieces referred to as degrees degrees


Two identical waves but they are 90 Two identical waves but they are 90 degreesdegrees out of phase with out of phase with each othereach other


In an ideal world, waves are created and In an ideal world, waves are created and transmitted from one station and received transmitted from one station and received perfectly intact at another station. perfectly intact at another station.

Unfortunately, RF communications do not Unfortunately, RF communications do not occur in an ideal world. occur in an ideal world.

There are many sources of interference and There are many sources of interference and many obstacles that will affect the wave in many obstacles that will affect the wave in its travels to the receiving station. its travels to the receiving station.


Understanding Keying MethodsUnderstanding Keying Methods

When data is sent, a signal is transmitted When data is sent, a signal is transmitted from the transceiver. In order for the data to from the transceiver. In order for the data to be transmitted, the signal must be be transmitted, the signal must be manipulated so that the receiving station manipulated so that the receiving station has a way of distinguishing 0s and 1s. has a way of distinguishing 0s and 1s.

This method of manipulating a signal so that This method of manipulating a signal so that it can represent multiple pieces of data is it can represent multiple pieces of data is known as a known as a keying methodkeying method. .


A keying method is what changes a signal into A keying method is what changes a signal into a carrier signal. It provides the signal with a carrier signal. It provides the signal with the ability to encode data so that it can be the ability to encode data so that it can be communicated or transported.communicated or transported.

There are three types of keying methods: There are three types of keying methods: Amplitude Shift Keying (ASK), Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Frequency Shift Keying (FSK), and Phase Shift Keying (PSK). Phase Shift Keying (PSK). These keying methods are also referred to as These keying methods are also referred to as

modulationmodulation techniques. techniques.


Amplitude Shift KeyingAmplitude Shift Keying Amplitude Shift Keying (ASK)Amplitude Shift Keying (ASK) varies the varies the

amplitude or height of the signal to amplitude or height of the signal to represent the binary data. represent the binary data.

one level of amplitude can represent a 0 bit one level of amplitude can represent a 0 bit and another level of amplitude can and another level of amplitude can represent a 1 bit. represent a 1 bit.


Fig. above shows how a wave can modulate an Fig. above shows how a wave can modulate an ASCII letter ASCII letter KK using Amplitude Shift Keying. The using Amplitude Shift Keying. The

larger amplitude wave is interpreted as a binary 1, larger amplitude wave is interpreted as a binary 1, and the smaller amplitude wave is interpreted as a and the smaller amplitude wave is interpreted as a

binary 0.binary 0.


This shifting of amplitude determines the This shifting of amplitude determines the data that is being transmitted. data that is being transmitted.

The way the receiving station performs this The way the receiving station performs this task is to first divide the signal being task is to first divide the signal being received into periods of time known as received into periods of time known as symbol periods. The receiving station then symbol periods. The receiving station then samples or examines the wave during this samples or examines the wave during this symbol period to determine the amplitude of symbol period to determine the amplitude of the wave. Depending upon the value of the the wave. Depending upon the value of the amplitude of the wave, the receiving station amplitude of the wave, the receiving station can determine the binary value. can determine the binary value.


wireless signals can be unpredictable and wireless signals can be unpredictable and also subject to interference from many also subject to interference from many sources. sources.

When noise or interference occurs, it usually When noise or interference occurs, it usually affects the amplitude of a signal. affects the amplitude of a signal.

Since a change in amplitude due to noise Since a change in amplitude due to noise could cause the receiving station to could cause the receiving station to misinterpret the value of the data, misinterpret the value of the data,

ASK has to be used cautiously.ASK has to be used cautiously.


Frequency Shift KeyingFrequency Shift Keying Frequency Shift Keying (FSK)Frequency Shift Keying (FSK) varies the varies the

frequency of the signal to represent the frequency of the signal to represent the binary data. binary data.

one frequency can represent a 0 bit and one frequency can represent a 0 bit and another frequency can represent a 1 bit another frequency can represent a 1 bit


Fig. above shows how a wave can modulate an Fig. above shows how a wave can modulate an ASCII letter ASCII letter KK using Frequency Shift Keying. The using Frequency Shift Keying. The faster frequency wave is interpreted as a binary 1, faster frequency wave is interpreted as a binary 1, and the slower frequency wave is interpreted as a and the slower frequency wave is interpreted as a

binary 0.binary 0.


FSK is used in some of the earlier 802.11 FSK is used in some of the earlier 802.11 standards. With the demand for faster standards. With the demand for faster communications, FSK techniques would require communications, FSK techniques would require more expensive technology to support faster more expensive technology to support faster speeds, making it less practical. speeds, making it less practical.

You may not realize it, but you have heard about You may not realize it, but you have heard about this before. AM/FM radio uses Amplitude this before. AM/FM radio uses Amplitude Modulation (AM) and Frequency Modulation (FM) Modulation (AM) and Frequency Modulation (FM) to transmit the radio stations that you listen to at to transmit the radio stations that you listen to at your home or in your automobile. The radio station your home or in your automobile. The radio station modulates the voice of music into its transmission modulates the voice of music into its transmission signal, and your home or car radio demodulates it.signal, and your home or car radio demodulates it.


Phase Shift KeyingPhase Shift Keying Phase Shift Keying (PSK)Phase Shift Keying (PSK) varies the phase varies the phase

of the signal to represent the binary data.of the signal to represent the binary data. one phase can represent a 0 bit and one phase can represent a 0 bit and

another phase can represent a 1 bit. another phase can represent a 1 bit.


Fig. above shows how a wave can modulate an Fig. above shows how a wave can modulate an ASCII letter ASCII letter KK using Phase Shift Keying. A phase using Phase Shift Keying. A phase change at the beginning of the symbol period is change at the beginning of the symbol period is

interpreted as a binary 1, and the lack of a phase interpreted as a binary 1, and the lack of a phase change at the beginning of the symbol period is change at the beginning of the symbol period is

interpreted as a binary 0.interpreted as a binary 0.


PSK is used extensively in the 802.11 standards.PSK is used extensively in the 802.11 standards. Typically, the receiving station samples the signal Typically, the receiving station samples the signal

during the symbol period and compares the phase during the symbol period and compares the phase of the current sample with the previous sample of the current sample with the previous sample and determines the difference. and determines the difference.

This degree difference, or differential, is used to This degree difference, or differential, is used to determine the bit value. More advanced versions determine the bit value. More advanced versions of PSK can encode multiple bits per symbol. of PSK can encode multiple bits per symbol. Instead of using two phases to represent the Instead of using two phases to represent the binary values, four phases can be used. Each of binary values, four phases can be used. Each of the four phases is capable of representing two the four phases is capable of representing two binary values (00, 01, 10, or 11) instead of one (0 binary values (00, 01, 10, or 11) instead of one (0 or 1), thus shortening the transmission time. or 1), thus shortening the transmission time.


When more than two phases are used, this is When more than two phases are used, this is referred to as Multiple Phase Shift Keying (MPSK). referred to as Multiple Phase Shift Keying (MPSK). Figure above shows how a wave can modulate an Figure above shows how a wave can modulate an ASCII letter ASCII letter KK using a Multiple Phase Shift Keying using a Multiple Phase Shift Keying method. Four possible phase changes can be method. Four possible phase changes can be monitored, with each phase change now able to monitored, with each phase change now able to be interpreted as 2 bits of data instead of just 1. be interpreted as 2 bits of data instead of just 1. Notice that there are fewer symbol times in this Notice that there are fewer symbol times in this drawing than there are in the drawing in the earlier drawing than there are in the drawing in the earlier fig.. fig..

Lesson 1

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