Wireless Communication

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Wireless Communication

• By Ching-Ting Na
• Steven Phan
• Stephanie Le

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Estimated to reach 700 Million cellular phone
users world-wide by the year 2003
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Multimedia Wireless Communications Any Time and
Anywhere
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Current Wireless Systems

• Cellular Systems
• Point-to-Point Wireless Links
• Wireless LANs

• Wireless WANs
• Satellite Systems
• HomeRF and Bluetooth

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Beyond VoiceWireless Applications

• Wireless Information Devices
• Wireless LANs
• Wireless Video/Music
• Multimedia Home Networks
• Smart Homes / Appliances
• Remote Learning / Medicine
• Autonomous Vehicles / Robots

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Historical Overview
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It Started with the Telegraph
We call the electric telegraph the most
perfect invention of modern times as
anything more perfect than this is scarcely
conceivable, and we really begin to wonder what
will be left for the next generation, upon which
to expend the restless energies of the human
mind. -- an Australian newspaper, 1853
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Critical Attributes ofTelecommunications Systems

• Speed
• Ability to transmit information in
  real-time
• Electronic transmission faster than
  transportation
• Coverage
• Beyond regional national and international
  in scale
• Metcalfs Law the more connected, the more
  useful
• Reliability

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Critical Attributes ofTelecommunications
Systems(Cont.)

• Cost
• 1866 20 word telegram cost 100 (4 months
  wages)
• Security
• Transmitted information as knowledge, news,
  secrets
• Always an element of government oversight and
  control

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Wireless Background
1907 Commercial Trans-Atlantic Wireless
Service Huge ground stations 30 x
100m antenna masts Beginning of
the end for cable-based telegraphy WW I
Rapid development of communications intelligence,
intercept technology,
cryptography 1920 Marconi discovers
shortwave (lt100 m) radio Longwave
follow contour of land Very
high transmit power, 200 KW
Shortwaves reflect, refract, and absorb, like
light Higher frequencies made
possible by vacuum tube
Cheaper, smaller, better quality transmitters
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Other Important Dates
1915 Wireless voice transmission NY to SF
1921 Police car dispatch radios, Detroit
1935 First telephone call around the world WW
II Rapid development of radio technology
1974 FCC allocates 40 MHz for cellular
telephony 1982 European GSM and Inmarsat
established 1984 Breakup of ATT 1984
Initial deployment of AMPS cellular system
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Mobile Telephony
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1st Generation

• Time Frame 1984 - 1996
• Frequency Band 800 MHz
• Services Analog Mobile Telephony
• Voice Band Data
• Examples AMPS, TACS, ETACS, NTT.

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2nd Generation

• Time Frame 1996 - 2000
• Frequency Band 800 1900 MHz
• Services Digital Voice
• Messaging
• Examples GSM, CDMA, TDMA..

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3rd Generation

• Time Frame 2000 - 2010
• Frequency Band 2 GHz
• Services High speed data
• Broadband video
• Multimedia
• Examples IMT-2000, UMTS.

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Communication

• (via cellular phones)

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Introduction

• Millions of people in the United States and
  around the world use cellular phones. They are
  such great gadgets -- with a cell phone, you can
  talk to anyone on the planet from just about
  anywhere!

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Introduction

• These days, cell phones provide an incredible
  array of functions, and new ones are being added
  at a very fast pace. Depending on the cell-phone
  model, you can
• Store contact information
• Make task or to-do lists
• Keep track of appointments and set reminders
• Use the built-in calculator for simple math
• Send or receive e-mail
• Get information (news, entertainment, stock
  quotes) from the Internet
• Play simple games
• Integrate other devices such as PDAs, MP3 players
  and GPS receivers

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How does a cellular phone work?
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The Cell Approach

• One of the most interesting things about a cell
  phone is that it is actually a radio -- an
  extremely sophisticated radio, but a radio
  nonetheless.
• It is a combination of two communication
  technologies.
• The telephone, which was invented by Alexander
  Graham Bell in 1876.
• Wireless communication, which can trace its roots
  to the invention of the radio by Nikolai Tesla in
  the 1880s (formally presented in 1894 by a young
  Italian named Guglielmo Marconi).

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Interesting Facts

• Most newer digital cellular phones have some sort
  of entertainment programs on them, ranging from
  simple dice-throwing games to memory and logic
  puzzles.
• Approximately 20 percent of American teens (more
  girls than boys) own a cellular phone.
• Cellular phones are more popular in European
  countries than they are in the United States --
  more than 60 percent of Europeans own a cell
  phone, compared to about 40 percent of Americans.

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In the dark ages

• people who really needed mobile-communications
  ability installed radio telephones in their cars.
  In the radio-telephone system, there was one
  central antenna tower per city, and perhaps 25
  channels available on that tower. This central
  antenna meant that the phone in your car needed a
  powerful transmitter -- big enough to transmit 40
  or 50 miles (about 70 km). It also meant that not
  many people could use radio telephones -- not
  enough channels.

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In the cellular age!!

• The genius of the cellular system is the division
  of a city into small cells.
• The cellular approach requires a large number of
  base stations in a city of any size.
• Each cell is typically sized at about 10 square
  miles.
• Each cell has a base station that consists of a
  tower and a small building containing the radio
  equipment (more on base stations later).
• Each carrier in each city also runs one central
  office called the Mobile Telephone Switching
  Office (MTSO).

• Cells in a hexagonal grid

http//www.howstuffworks.com/
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Advantages in the cellular approach

• Division of a city into small cells allows
  extensive frequency reuse across a city.
• A single cell in an analog system uses
  one-seventh of the available duplex voice
  channels.
• Each cell (of the seven on a hexagonal grid) is
  using one-seventh of the available channels so it
  has a unique set of frequencies and there are no
  collisions
• A cell-phone carrier typically gets 832 radio
  frequencies to use in a city.
• Each cell phone uses two frequencies per call --
  a duplex channel -- so there are typically 395
  voice channels per carrier. (The other 42
  frequencies are used for control channels)
• Therefore, each cell has about 56 voice channels
  available.
• The same frequencies can be reused in
  non-adjacent cells (more on this later).
• With digital transmission methods, each cell has
  about 168 voice channels available.

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Low-power transmitters

• Cell phones have low-power transmitters in them.
• Many cell phones have two signal strengths 0.6
  watts and 3 watts (for comparison, most CB radios
  transmit at 4 watts).
• The base station is also transmitting at low
  power.
• Low-power transmitters have two advantages
• The transmissions of a base station and the
  phones within its cell do not make it very far
  outside that cell. Therefore, in the figure
  above, both of the purple cells can reuse the
  same 56 frequencies. The same frequencies can be
  reused extensively across the city.
• The power consumption of the cell phone, which is
  normally battery-operated, is relatively low. Low
  power means small batteries, and this is what has
  made handheld cellular phones possible.

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Cell phone codes

• All cell phones have special codes associated
  with them.
• Electronic Serial Number (ESN) - a unique 32-bit
  number programmed into the phone when it is
  manufactured (permanent).
• Mobile Identification Number (MIN) - a 10-digit
  number derived from your phone's number
  (programmed into the phone when you purchase a
  service plan and have the phone activated).
• System Identification Code (SID) - a unique
  5-digit number that is assigned to each carrier
  by the FCC
• ESN is permanent, but MIN and SID are programmed
  into the phone when you purchase a service plan
  and have the phone activated).
• These codes are used to identify the phone, the
  phone's owner and the service provider.

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Inside a Cell Phone

• Components of a cell phone
• A circuit board containing the brains/CPU of the
  phone
• An antenna
• A liquid crystal display (LCD)
• A keyboard
• A microphone
• A speaker
• A battery

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Inside a Cell Phone

• The circuit board is the heart of the system.

The back of circuit
The front of circuit
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Inside a Cell Phone

• Components and functions
• The microprocessor
• handles all of the housekeeping chores for the
  keyboard and display, deals with command and
  control signaling with the base station and also
  coordinates the rest of the functions on the
  board
• The analog-to-digital and digital-to-analog
• conversion chips translate the outgoing audio
  signal from analog to digital and the incoming
  signal from digital back to analog.
• The digital signal processor (DSP)
• processor designed to perform signal-manipulation
  calculations at high speed.

• microprocessor

http//www.howstuffworks.com/
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Inside a Cell Phone

• The ROM and Flash memory
• provide storage for the phone's operating system
  and customizable features, such as the phone
  directory.
• The radio frequency (RF) and power section
• handles power management and recharging, and also
  deals with the hundreds of FM channels.
• the RF amplifiers
• handle signals traveling to and from the antenna.

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Inside a Cell Phone

• The display has grown considerably in size as the
  number of features in cell phones have increased.

• Most current phones offer built-in phone
  directories, calculators and even games. And many
  of the phones incorporate some type of PDA or Web
  browser.

Flash memory card on board
http//www.howstuffworks.com/
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Inside a Cell Phone
speaker
microphone
battery backup
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I know what happened when someone tries to call
you(part 1)

• When you first power up the phone, it listens for
  an SID on the control channel.
• The control channel is a special frequency that
  the phone and base station use to talk to one
  another about things like call set-up and channel
  changing. If the phone cannot find any control
  channels to listen to, it knows it is out of
  range and displays a "no service" message.
• When it receives the SID, the phone compares it
  to the SID programmed into the phone. If the SIDs
  match, the phone knows that the cell it is
  communicating with is part of its home system.

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I know what happened when someone tries to call
you(part 2)

• Along with the SID, the phone also transmits a
  registration request, and the MTSO keeps track of
  your phone's location in a database -- this way,
  the MTSO knows which cell you are in when it
  wants to ring your phone.
• The MTSO gets the call, and it tries to find you.
  It looks in its database to see which cell you
  are in.
• The MTSO picks a frequency pair that your phone
  will use in that cell to take the call.

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I know what happened when someone tries to call
you(part 3)

• The MTSO communicates with your phone over the
  control channel to tell it which frequencies to
  use, and once your phone and the tower switch on
  those frequencies, the call is connected.
• As you move toward the edge of your cell, your
  cell's base station notes that your signal
  strength is diminishing. Meanwhile, the base
  station in the cell you are moving toward (which
  is listening and measuring signal strength on all
  frequencies, not just its own one-seventh) sees
  your phone's signal strength increasing. The two
  base stations coordinate with each other through
  the MTSO, and at some point, your phone gets a
  signal on a control channel telling it to change
  frequencies. This hand off switches your phone to
  the new cell.

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Roaming

• If the SID on the control channel does not match
  the SID programmed into your phone, then the
  phone knows it is roaming.
• The MTSO of the cell that you are roaming in
  contacts the MTSO of your home system
• The MTSO checks its database to confirm that the
  SID of the phone you are using is valid
• Your home system verifies your phone to the local
  MTSO
• The MTSO tracks your phone as you move through
  its cells.

http//www.howstuffworks.com/
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Cell Phones and CBs

• A good way to understand the sophistication of a
  cell phone is to compare it to a CB radio or a
  walkie-talkie.
• Simplex vs. duplex - Both walkie-talkies and CB
  radios are simplex devices. That is, two people
  communicating on a CB radio use the same
  frequency, so only one person can talk at a time.
  A cell phone is a duplex device. That means that
  you use one frequency for talking and a second,
  separate frequency for listening. Both people on
  the call can talk at once.
• Channels - A walkie-talkie typically has one
  channel, and a CB radio has 40 channels. A
  typical cell phone can communicate on 1,664
  channels or more!
• Range - A walkie-talkie can transmit about 1 mile
  (1.6 km) using a 0.25-watt transmitter. A CB
  radio, because it has much higher power, can
  transmit about 5 miles (8 km) using a 5-watt
  transmitter. Cell phones operate within cells,
  and they can switch cells as they move around.
  Cells give cell phones incredible range. Someone
  using a cell phone can drive hundreds of miles
  and maintain a conversation the entire time
  because of the cellular approach.

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Wireless Communication

• Benefits and Risks

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Wireless Communication Benefits

• For individuals, wireless communication provides
  convenience, convenience, convenience
• In industries, such as health care, wireless
  communication can improve their services

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Wireless Communication Benefits Individuals

• How many people have cell phones, palm pilots?
• Over 90 million people have cell phones, and palm
  pilots

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Wireless Communication Benefits Individuals

• Economic They allow us to conduct business while
  stuck in traffic
• Personal Safety They make it easier to call for
  help in an emergency
• Mechanical Roadside assistance is just a phone
  call away
• Access We could stay in touch with loved ones
  and colleagues
• Money Saving Its sometime cheaper to call
  long-distance from our cars than from our homes

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Wireless Communication Benefits Industries

• Health Care Industry
• Today's applications in wireless devices can
  handle tasks such as basic forms of charge
  capture, prescription writing, clinical
  documentation, lab test management, and alert
  messaging/communication.

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Wireless Communication Benefits Health Care

• Some examples of how wireless devices can help
  the Health Care industry
• e-Encounters
• e-Prescriptions
• e-Disease Management

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Wireless Communication Risks

• The 2 S Risks
• Security
• Safety

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Wireless Communication Risks Security

• Major concern for the Industry
• There is no universal industry standard or
  functional protocol for wireless devices such as
  cell phones and PDAs, therefore, we cant have
  truly effective security protocol

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Wireless Communication Risks Security

• WAP is short for Wireless Application Protocol,
  and is the standard that is used to connect
  PDAs, mobile phones and other wireless devices
  to the Internet.
• WAP offers WTLS-based security
• WTLS has security encryption but has some issues
  with data gram truncation, message forgery
  attack, and key-search shortcut for some
  exportable keys.

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Wireless Communication Risks Security

• New features, new frequency allocation, BUT no
  time to develop security
• Lack of transparency

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Wireless Communication RisksSafety

• Dangerous when driving and using a wireless
  device
• NHTSA has determined through research that driver
  inattention is a primary or contributing factor
  in as many as 50 of all traffic accidents

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Wireless Communication Risks Safety

• Any danger between cell phone use and brain
  cancer?
• Answer is YES and NO
• The lack of ionizing radiation and the low energy
  level emitted from cell phones and absorbed by
  human tissues make it unlikely that these devices
  cause cancer. Moreover, several well-designed
  epidemiological studies find no consistent
  association between cell phone use and brain
  cancer.

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Wireless Communication Risks Safety

• George Carlo is a public health researcher who
  spearheaded a three-year, 27 million research
  program for the cellular telephone industry on
  possible health risks associated with such
  devices.
• In his medical journal, Medscape General
  Medicine,he states that radio frequency radiation
  from wireless phone antennae "appears to cause
  genetic damage in human blood," while another
  case study uncovered a "statistically significant
  increase" in neuro-epithelial brain tumors among
  cell phone users.

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Wireless Communication Risks Safety Tips

• Handheld users should wear a headset and clip the
  phone on their belt, moving antenna far from head
  to reduce risk of brain cancer.
• Buy a "hands-free" kit for your car and use an
  external antenna (this should also help reduce
  the risk of "talking-and-driving" accidents).
• The U.K. Ministry of Health warns against
  cell-phone use by children.

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Wireless Communication Risks Safety Tips

• Pregnant women should avoid using cell phones.
• Check the radiation information that the CTIA
  mandated for inclusion in all cell-phone boxes,
  available by fall 2000 (this information is
  available at point-of-sale in U.K.).
• Buy a cell-phone with the lowest radiation
  output.

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Wireless Communication Questions To Ponder

• Should states control the usage of wireless
  devices while driving?
• What kind of ethics are behind using wireless
  devices?
• Shouldnt all people reframe from using cell
  phones while driving so that they dont put
  others at risk?
• Are companies liable for health-risks which
  involve using wireless devices?

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Wireless Communication Summary

• Wireless Communication can be of great advantage
  to individuals and companies because they provide
  an easy way to communicate with one another
• There are risks involved such as security and
  privacy, which both parties need to take into
  consideration