Cellular Fundamentals

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Cellular Fundamentals

• 3G Technologies
• Bellevue Community College
• Bob Young, Instructor

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Overview of 3G

• Transform wireless communications into on-line,
  real-time connectivity
• Immediate access to location-specific services
• Information on demand

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A shift in focus

• 3G wireless technology represents a shift from
  voice-centric services to multimedia-oriented
  (voice, data, video, fax) services.

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Market "Drivers"

• Remote access to personalized data
• Multimedia management
• Interoperability between a mobile terminal
  (phone, PDA etc.) and other electronic devices
• Synchronization and uploading of information
• Increasing use of the Internet has created a
  demand for wireless access to the same data

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What is 1G?

• Analog wireless voice telephone service
• Circuit switching technology
• Examples
• In USA, AMPS (Advanced Mobile Phone Service)
• In Europe and elsewhere, TACS (Total Access
  Communication Systems)

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What is 2G? (part 1)

• Early digital mobile phones
• Still using circuit switching technology
• Examples
• GSM (Global System for Mobiles)
• NA-TDMA
• CDMA

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What is 2G? (part 2)

• Some advanced voice services, such as Caller ID
• Some data capabilities, such as fax and SMS
  (Short Message Service)
• Data rates typically limited to about 9600 bps
• Not suitable for web browsing
• Not suitable for multimedia services

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What is 2.5G? (part 1)

• A stepping stone towards 3G
• Higher bandwidths, up to about 384 Kbps in some
  cases

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What is 2.5G? (part 2)

• Examples
• High Speed Circuit-Switched Data (HSCSD)
• General Packet Radio Service (GPRS)
• Enhanced Data Rates for Global Evolution (EDGE)

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What is High Speed Circuit Switched Data?

• HSCSD is one step towards 3G wideband mobile data
  networks.
• Upgrade to GSM systems
• Circuit-switched technology
• Data rates up to 57.6 Kbps

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HSCSD implemented in

• Parts of Europe
• Hong Kong
• Singapore
• Israel
• South Africa
• (To my knowledge, never implemented in USA)

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How does HSCSD achieve 57.6 Kbps?

• Uses 14.4 kbps data coding
• Aggregates 4 radio channel timeslots of 14.4 Kbps
• 4 x 14.4 57.6 Kbps

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What is General Packet Radio Service?

• GPRS is an intermediate step towards Internet
  Services
• Used on GSM networks
• Packet based technology

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GPRS Data rates up to 115 Kbps

• Some deployed systems are only experiencing 20 -
  30 Kbps!

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GPRS and IS-136

• GPRS can be overlaid on IS-136 (NA-TDMA) networks
• (Standards agreement reached in 1999)

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GPRS implemented in

• Parts of Europe
• Hong Kong
• United Kingdom
• United Arab Emirates
• USA
• several other countries

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How does GPRS achieve 115 Kbps?

• Looks up user profile in HLR/VLR to determine
  data rate allowed
• Assigns multiple time slots (1 to 8) to achieve
  higher data rates

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GPRS is packet based

• Data is packetized and transported over an IP
  backbone

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GPRS is compatible with

• SMTP/POP
• FTP
• HTTP
• Telnet
• and other IP services

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GPRS Network

• Serving GPRS Support Node is the mobile's access
  to the data network
• Gateway GPRS Support Node is the PLMN access to
  the Internet
• Voice calls are still routed through the MSC
• (see next slide for details)

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GPRS Network
GPRS Network
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What is EDGE?

• Enhanced Data Rates for Global Evolution
• Increases throughput for both HSCSD and GPRS
• Triples the data rate per time slot

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EDGE for HSCSD is called ECSD

• Peak data rate is 64 Kbps, but uses fewer time
  slots.
• EDGE for GPRS is called EGPRS.
• Peak data rate using all 8 time slots, can exceed
  384 Kbps.
• In practice, many operators are seeing only
  approximately 100 Kbps!

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Ericsson's Definition of EDGE (part 1)

• "A technology that gives GSM the capacity to
  handle services for the third generation of
  mobile telephony."

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Ericsson's Definition of EDGE (part 2)

• "EDGE uses the same TDMA (Time Division Multiple
  Access) frame structure, logic channel and 200kHz
  carrier bandwidth as today's GSM networks, which
  allows existing cell plans to remain intact."

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Note that Ericsson calls EDGE a "third
generation" technology.

• This may be more marketing hype than reality.
• Most industry insiders consider EDGE a 2.5G
  "stepping stone" technology to 3G.

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EDGE is part of a larger transition

• "A year and a half into our program, we believe
  the decision to migrate to GSM and GPRS/EDGE/3GSM
  was THE best solution and decision for our
  company, our customers, and our shareholders...."
  
• - Rod Nelson, CTO, ATT Wireless

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What is 3G?

• Convergence to a single global system
• Data speeds that support streaming audio/video
• Packet switched
• Full support for m-commerce
• Voice becomes a feature - perhaps not the driving
  characteristic - of the network

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Hutchison on 3G

• "There's nothing like 3G on the market at the
  moment. 3G is fusing together two of the most
  powerful consumer technologies in history - the
  Internet and the mobile phone."
• - Hutchison 3G spokesman Edward Brewster

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All paths to 3G involve CDMA technologies
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CDMA technology is recognized as providing

• Clearer voice quality
• Less background noise
• Fewer dropped calls
• Enhanced security
• Greater reliability
• Greater network capacity

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The ITU has approved 3 standards for 3G mobile
systems

• TD-SCDMA
• W-CDMA
• CDMA2000

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What is TD-SCDMA?

• Standard formulated by China
• No further discussion in this presentation

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What is W-CDMA?

• Also called UMTS
• Packet technology for 3GSM
• Current data rate 384 Kbps
• Future data rate 1.5 to 2 Mbps
• Then 8 - 10 Mbps

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What is 3GSM?

• "The technology on which 3GSM services will be
  delivered is built around a core GSM network with
  a Wideband-CDMA (W-CDMA) air interface, which has
  been developed as an open standard. Already over
  85 of the world's network operators have chosen
  3GSM's underlying technology platform to deliver
  their third generation services. 3GSM is a key
  element of GSM-The Wireless Evolution." ( - GSM
  Association)

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3GSM Network

• BSS is replaced by RNS
• BSC is replaced by RNC
• BTS is replaced by Node B
• (see next slide for details)

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What is CDMA2000?

• Full backward compatibility with IS-95B

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CDMA 1x (CDMA2000)

• Single carrier, 1.2288 MHz (each, uplink and
  downlink)
• Data rate 144 Kbps now, 307 Kbps in the future
• Considered 2.5G, not 3G

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CDMA 1x EV-DO (CDMA2000)

• Stands for "1x Evolution - Data Only"
• Data rate 384 kbps - 2.4 Mbps
• 3G technology

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CDMA 1x EV-DV (CDMA2000)

• Stands for "1x Evolution - Data and Voice"
• Data rate 4.8 Mbps
• 3G technology

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CDMA 3x (CDMA2000)

• Combines 3 carriers 3 x 1.2288 MHz 3.6864 MHz
• Data rate 2 Mbps and higher

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Paths to 3G
Paths to 3G
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3G Spectrum Around the World
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Subscriber Growth In USA