Cell Phones and Standards

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Cell Phonesand Standards
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Cell Phones

• Standards
• Cell Phone Technologies
• 1G, 2G and 3G
• Determining a standard
• Wireless Networking

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Setting Standards

• Three main ways that standards get set in
  practice
• (I) De-facto standards, i.e., standards set
  primarily by the market. These standards are
  often proprietary.
• Examples Microsoft Office and Windows, Java,
  TCP/IP
• Often fast to develop and can be changed readily
• But are usually proprietary and may not be open
• US and cell phones
• (II) Voluntary industry agreements, where
  standards are often jointly developed. These
  standards are typically open standards, that is,
  they are not proprietary. Example bar codes
• (III) Standards imposed by National Standards
  Bodies (NSBs), or agreed upon by regional or
  international standards development organizations
  (SDOs).
• Examples meter
• Slow to develop
• Non-proprietary
• Europe and cell phones

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Move to a New Standard
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Move to a Single Standard
Why?
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Tipping

• The economic theory of tipping would suggest that
  the early adoption of one standard or the
  decision to formally set one standard in the
  European Union (EU) could tip the whole world
  toward that standard.
• The adoption of a single standard by a few large
  firms will likely tip the entire market toward
  that standard.
• In market competition between wireless standards,
  interconnection may mean that the standard
  tipping results may apply only if one standard
  gets far out in front of a competing standard
  early on before the competing standard has a
  chance to get established.

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Cell Phone Technologies

• Cellular system divides a coverage area into
  small cells.
• This allows extensive frequency reuse.
• In a typical analog cell-phone system in the
  United States, the cell-phone carrier receives
  about 800 frequencies to use across a city.
• The carrier chops up the city into cells. Each
  cell is typically sized at about 10 square miles
  (26 square kilometers).
• Cells are normally thought of as hexagons on a
  big hexagonal grid

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Note 7 cells in pattern
From Mukesh Raghuraman 2003
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Hexagon grid - Cell
Cell base Station
Call Handoff
Coverage area Cell
From Mukesh Raghuraman 2003
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Movement Between Cells

• Ability to change frequency/channel as the unit
  moves from one cell to another cell.
• Enables the concept of frequency reuse. Because
  cell phones and base stations use low-power
  transmitters, the same frequencies can be reused
  in non-adjacent cells.
• The ability that made the cellular system
  possible.

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Cell Phone Standards
Note wide divergence of standards Not all
frequencies/ standards shown
From Mukesh Raghuraman 2003
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1G - Analog Cell Phone Basics

• In US, the analog cell-phone standard called AMPS
  (Advanced Mobile Phone System) was approved by
  the FCC and first used in Chicago in 1983.
• Each cell has a base station that consists of a
  tower and a small building containing the radio
  equipment
• A single cell in an analog system uses
  one-seventh of the available duplex voice
  channels. That is, 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 (395/7).
• In other words, in any cell, 56 people can be
  talking on their cell phone at one time. (Note
  all of the above is for ANALOG systems) pretty
  hopeless for Iowa City!

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1G Analog Problems

• Cell phones
• Limited battery life (typically 8 hours)
• Limited range could have more powerful cell
  phone mounted in cars
• Security
• None easy to listen in
• E.g. Squidgy-gate and Camilla-gate (1992)
• Very limited number of voice channels

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Analog and Digital

• Analog each conversation occupies whole
  channel. Limits number of open lines in each
  cell. Frequency Division Multiple Access (FDMA)
• Digital conversation compressed using 0, 1s and
  sent out in shorter time. Can share each
  frequency. Time Division Multiple Access (TDMA)

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Digital (most of 2G)
Analog
From The Economist

• Analog each conversation occupies whole
  channel. Limits number of open lines in each
  cell. Frequency Division Multiple Access (FDMA)
• Digital uses 0, 1s, compressed and sent out in
  shorter time. Can share each frequency. Time
  Division Multiple Access (TDMA)

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FDMA

• FDMA separates the spectrum into distinct voice
  channels by splitting it into uniform chunks of
  bandwidth.
• FDMA is used mainly for analog transmission.
  While it is certainly capable of carrying digital
  information, FDMA is not considered to be an
  efficient method for digital transmission.

From How Stuff Works
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TDMA 2G

• Compression of digital signal allows signal to be
  sent out in shorter time.
• Usually for TDMA, each conversation takes up one
  third of channel.
• Note more frequencies set aside for 2G
• Nearly all US and Europe 2G systems use TDMA
  (exceptions include SprintPCS, CDMA)
• Can also include encryption

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Another Way to Increase Number of Simultaneous
Conversations - CDMA

• Code-division Multiple Access (CDMA)
• Involves spreading a radio signal out over a
  range of frequencies.
• Each transmission is scrambled using a random
  code
• Allows for more simultaneous conversations than
  other approaches
• Handsets stop transmitting when the user isnt
  talking allows more conversations
• FDMA is akin to a party at which everybody talks
  simultaneously, but each pair of speakers
  converses at a different musical pitch, from
  booming bass to piping treble. A system in which
  party-goers took turns to speak at different
  pitches would be like TDMA. And everybody talking
  at once, only in different languages (so that
  other conversations are rendered
  incomprehensible), would be equivalent to CDMA.
  (The Economist, 2003)

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2G Advantages Over 1G

• Cell phones
• Increased battery life (significantly more than 8
  hours)
• Increased range
• Security
• Possible to encrypt signals
• Increased number of voice channels

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2G Standard - GSM

• Global System for Mobile communications (GSM).
• Mandated for use in Europe
• In US, companies were allowed to develop and use
  their own choice of standard for 2G
• Result
• Europe single 2G standard GSM
• US multiple standards. Some companies use GSM
  but on a different frequency from Europe.
  Standards uses include TDMA, GSM and CDMA

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Move to Increase Bandwidth

• Increase bandwidth allows for larger amount of
  data to be received web browsing, pictures,
  video, music at increased quality.
• How to do this
• 2.5G approaches build on 2G systems
• 3G systems new systems with increased bandwidth
  over 2.5G systems
• Bandwidth
• 2G data rates 9.6 Kbps 14.4 Kbps.
• 2.5G data rates 64 144 Kbps.
• 3G data rates144 Kbps. to 2 Mbps. Live high
  quality video requires 2Mbps.

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2.5G

• Uses General Packet Radio Services (GPRS)
• GSM and TDMA enhanced to packet based networks
  IP based (the available radio resource can be
  concurrently shared between several users)
• GPRS is primarily a simple software upgrade on
  GSM and TDMA
• Relatively easy for the service providers to
  update their networks
• Can simultaneously make telephone calls and
  transmit data.
• Expect to see this generally in place over the
  next few years e.g. ATT moving to GSM with
  GPRS

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3G

• High data rates
• 144 kbits/sec or higher in high mobility
  (vehicular) traffic
• 384 Kbits/sec for pedestrian traffic
• 2 Mbits/sec or higher for indoor traffic
• Different Standards
• WCDMA Europe and Japan
• CDMA2000 from Qualcomm used in USA, Korea
• TD-S CDMA China

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Vodafone advertisement
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Setting Standards

• Europeans set standard for 2G GSM while US
  companies were free to develop their own standard
• Did the imposition of a standard for 2G help the
  Europeans?

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2G Europe and Setting a Single Standard

• Features work across companies e.g. text
  messaging
• Larger economies of scale in the production of
  both terminals/handsets and network
  infrastructure equipment reduce costs and
  increase availability.
• Increase market share for European companies?
• Variety of terminal equipment (handsets) tends to
  be greater.
• Larger number of purchasers of service since
  single standard. By the end of 1993 there were
  already more than 1 million GSM users in Europe.
  By contrast, in the U.S., the FCC did not even
  complete its first auction allocating PCS
  spectrum until March of 1995. (Could also be
  partly due to high costs of traditional European
  phone companies).
• Wider coverage area (perhaps)

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Text Messaging

• Large difference between Europe and US
• Ireland around 70 per month, USA 7 per month
• Messaging accounts for 20 of revenue for EU cell
  phone companies.
• Why?

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Market Impact of European Cell Phone Handset
Manufacturers
From The Economist 10/12/2000
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(No Transcript)
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SprintPCS National Coverage
Dark Green Digital Coverage Light Green
Analogue Coverage
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SprintPCS New Mexico Coverage
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Benefits From Multiple (Competing) Standards

• Types of services tend to differ across
  technologies. For example, CDMA networks have
  offered more and better data services than were
  available on GSM networks.
• More technological competition (highly
  centralized approach foregoes the benefits of
  competition in research and development)
• Greater price competition (at least early on)
  among competing incompatible standards (perhaps)
• Wider coverage area (perhaps)

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Setting 3G Standards

• Two main standards have been proposed
• Wideband CDMA (WCDMA) for Europe and
• CDMA2000 for US and other countries
• CDMA2000 is a natural migration from CDMA-One
  (the 2G CDMA standard),
• while WCDMA is essentially incompatible with any
  existing technology.

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Will a Single 3G European Standard Help the
Europeans

• Not clear
• 3G does not show real signs of take off. Who will
  use it?
• Will consumers be happy with 2G and 2.5G?
• Will WCDMA work as promised?
• Will CDMA2000 build a huge lead worldwide?
• Will 802.11g, 802.11a, or 802.16 (WiMax) take
  over?

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WiMAX

• WiMAX, an acronym that stands for Worldwide
  Interoperability for Microwave Access, is a
  certification mark for products that pass
  conformity and interoperability tests for the
  IEEE 802.16 standards. Shared data rates up to 70
  Mbit/s http//en.wikipedia.org/wiki/Wimax
• Aim for line of sight of 30 miles (15 miles
  non-line of sight). Can cover a metropolitan
  district. http//en.wikipedia.org/wiki/Wimax
• First products expected in 2005. See, for
  example, http//www.egovmonitor.com/node/691/

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Wireless Internet Access

• 3G data rates
• 144 kbits/sec or higher in high mobility
  (vehicular) traffic
• 384 Kbits/sec for pedestrian traffic
• 2 Mbits/sec or higher for indoor traffic
• 802.11g data rate of 20Mbit/sec, 802.11a data
  rate of about 24Mbit/sec
• Usually limited by other parts of the network
• Limited range 300 feet, more with antenna.
  Office environment, Iowa City?
• Voice over IP (VoIP) handsets possible