Cellular Phones as Embedded Systems

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					  Cellular Phones as
  Embedded Systems
               EEL 6935 - Embedded Systems
Dept. of Electrical and Computer Engineering
                          University of Florida



                                                  Liza Rodriguez
                                                  Aurelio Morales
    Outline

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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    Outline

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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   Cellular Generations
o Analog Cellular Technology (1G)
    Early 1980’s
    NMT, AMPS (FDMA)
    Susceptible to noise and interference. No protection.
o Digital Mobile Communication (2G, 2.5G)
      Early 1990’s
      GSM (TDMA), IS-95 (CDMA), IS-136 (D-AMPS, TDMA), PDC (TDMA)
      Data services: SMS
      Digital encryption of conversations. Enhanced privacy.
o Wide Band Mobile Communication (3G, 3.5G)
      Early 2000’s
      EDGE (TDMA), CDMA 2000, UMTS (CDMA)
      Data transfer rates >= 2 Mbit/s
      Data & Voice convergence, Internet access.

o Broadband Mobile Communication (4G)
    LTE Advanced, IEEE 802.16 (WiMAX)
    Data transfer rates >= 100 Mbits/s
    Mobile IPTV, Wireless VoIP.
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 Introduction (cont.)
Evolution of Radio Systems, Mobility, Data Rates




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Introduction (cont.)
Digital Convergence

• Convergence enables people to create, share and
  consume digital content, using interoperable devices
• Cellular phones evolve from traditional cost-optimized
  handhelds to multifunctional terminals
• Cellular phones: key platform for mobile convergence
  applications (web browsing, video streaming, etc.)




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    Agenda

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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Today’s Cellular Phone

• Extremely complex embedded system
• Functional blocks are custom-made for mobility
• Chips are either proprietary designs or based
  on available chips.
• Miniaturization and functionality




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Block diagram of triple-band cellular phone




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Example: Blackberry Bold




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Example: Blackberry Bold




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Example: Blackberry Bold




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Example: Blackberry Bold




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Example: Nokia N95




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Example: Nokia N95




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Example: Nokia N95




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Example: Nokia N95




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    Agenda

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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Development of Cellular phones
• Miniaturization
• Functionality




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    Baseband and RF domains challenges
       Challenge               Possible solution                         New Challenges

Baseband ASICs are           Decentralized architectures:            Management of processing
limited in performance by    small distributed controller            power resources
computational power, on-     processors running at lower
chip communication and       frequencies
clock distribution

Baseband flexibility and     Use configurable logic,                 Design methodology,
support for multiple radio   configurable processors, or             verification and testability
systems                      processor generators

RF Cost and size of          RF on digital CMOS                      Substrate-coupling effects,
BiCMOS chips                 technology                              device models

RF design portability        RF on digital CMOS                      New RF circuits and
                             technology                              architectures based on fast
                                                                     sampling and time-discrete
                                                                     signal processing needed

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RF challenges: Multiradio



                                             o Wide variety of radio
                                               systems
                                             o Combination of systems at
                                               reasonable cost and size
                                             o Interference
                                             o Miniaturization challenges
                                                   Antennas
                                                   Filters




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    Outline

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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Memory Challenge
• Total memory requirement is increasing rapidly
• Mass Memories – interactive games, high
  quality video
     • Large memories are required to support data
       downloading and local storage
     • Supported by external memory cards: MMC or SD

• Small Memories – processing and small
  applications
     • Memory chips and their interconnections consume large
       areas on PCBs and are accessed frequently
     • New types of NVRAM may challenge memory chips to
       provide smaller and more cost effective memory solutions
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NVRAM – Alternatives to Flash Memory
• Ferroelectric RAM (FeRAM)
      • DRAM cell with ferroelectric dielectric in the storage capacitor
      • Advantages: low power, faster reads and writes (single word vs. entire
        block erase), greater number of write-erase cycles (1016 vs. 106)
      • Disadvantages: lower storage density, higher cost

• Phase Change Memory
      • Glass cells that become crystalline
        or amorphous by cooling
      • Advantages: faster reads and writes,
        greater number of write-erase cycles
        (108 vs. 106), longer hold times
      • Disadvantages: temp sensitivity,
        no pre-programming

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Application Platform
• Mobile internet – web browsing, video
  calls and high bit rate streaming
• Java ME – provides flexible user
  interfaces, built in network protocols,
  multimedia support
     • Fact: 2.1 Billion mobile phones use
       Java platforms
• 3rd Party Mobile Applications – if
  developed in Java, are portable
  enough to run on almost all cell phones


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Java – Hardware or Software?
• Hardware – an additional small processor dedicated for
  running Java
    • Improves performance, minimizes memory requirements
    • Software becomes dependent on inflexible hardware
      implementation

• Software – Java is run on
  baseband processor
    • Virtual machine – Java commands
      are interpreted as equivalent
      microprocessor commands -- slow!
    • Just In Time – compiler that would
      translate Java classes into processor
      instructions --- fast!
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Power Challenge
• Recent evolution of communication and application
  functions have substantially increased power
  consumption
• Constant annual growth of 10% in battery capacity has
  enabled battery volume shrinkage while having mAh
  level constant
• However, when 3G or WLAN communication is run
  simultaneously with multimedia applications, power
  consumption must be reduced




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Power consumption and Battery Capacity




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Solutions to Power Gap
• 10% increase in battery capacity will continue forever
• Reduce power hungry components:
     • Antennas – Bluetooth, Wi-Fi, RF
     • Digital displays

• Dynamic voltage and frequency scaling (DVFS)
• Reconfigurable RF components to reduce the number
  of ICs.




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    Outline

    • Introduction
    • Today’s Cellular Phone
    • Architecture Challenges for Wireless Access
    • Memory, OS, and Power Challenges
    • Conclusions




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Conclusions
• Cellular phones have come a long way from analog
  communication devices to digital mobile computers.
• Today, a cellular phone is a paradigm of an embedded
  system having highly optimized cost, size, efficiency
  and performance.
• Challenges in RF circuits, implementation architecture,
  memory, and power consumption are still affecting the
  development and growth of mobile devices.
• New technologies such as decentralized architectures,
  reconfigurable circuits, advanced memories, and low
  power designs will help overcome challenges.


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 References

 • http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1332581
 • http://en.wikipedia.org/wiki/Mobile_phone
 • http://www.portioresearch.com/resources.html
 • http://www.phonewreck.com/wiki/index.php?title=BlackBerry_Bold
 • http://www.phonewreck.com/wiki/index.php?title=Nokia_N95




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           Questions?




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