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Bluetooth, IEEE 802.11


Bluetooth, IEEE 802.11 & Cell Phone Systems--Arun Radhakrishnan--Thierry Fernaine--Vipul Gautam – PowerPoint PPT presentation

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Title: Bluetooth, IEEE 802.11

Bluetooth, IEEE 802.11 Cell Phone Systems
  • --Arun Radhakrishnan
  • --Thierry Fernaine
  • --Vipul Gautam

  • What is Bluetooth? -- Vipul
  • Specifications and Protocols
  • What is 802.11? -- Arun
  • Specifications and Protocols
  • 802.11 vs. Bluetooth
  • Cellular Phone Systems -- Thierry
  • CDMA
  • TDMA
  • FDMA
  • Generations of cell phones (1G to 4G)
  • Experiments/Demonstrations
  • Summary and Future Plans

  • Brainstorming the tasks involved in the project
  • 15th February, 2003
  • Information on Bluetooth and 802.11
  • 25th February, 2003
  • Analyzing Bluetooth vs 802.11
  • 28th April, 2003
  • Obtaining materials on phone systems (CDMA, TDMA,
  • 23rd April, 2003
  • Information about 3G and 4G
  • 17th April, 2003
  • Talking to a professor about doing an experiment
    on wireless
  • 10th March, 2003
  • Observing the experiment performed by a TA
  • 2nd April, 2003

  • Protocol for the efficient transmission of data
  • Designed for devices such as cell phones,
    printers, PDAs, notebook computers, fax machines

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  • Low power link
  • Short time data transfers
  • Small indoor distances
  • Line of Sight is not required
  • Better than IR link

Bluetooth Specification Protocol Stack
  • Operates in the 2.4GHz band
  • Unlicensed band
  • Uses frequency hopping
  • 2.4 to 2.4385 GHz
  • 79 hopping frequencies separated by 1 MHz
  • Data rate ? 1Mbps

Frequency Hopping
Frequency Hopping
  • Characterized by its system of fast frequency
  • 10 different types of hopping sequences are
  • 5 of the 79 MHz range/79 hop system and 5 for
    the 23 MHz range/23 hop system.
  • The different range system's hopping sequences
    differ in frequency range 79MHz / 23MHz, and
    segment length 32 hops(79MHz system) / 16
    hops(23MHz system).

Frequency Hopping
  • Assurance of high quality communication in large
    urban centers and high-capacity networks
  • The millisecond rhythm with which the change of
    frequency takes place enables interference to be
    eliminated and prevent fading effects.
  • Deployed primarily in the military sector as well
    as in diplomatic communications via radio due to
    its unique bug-proof characteristics.

Data Layer
  • Piconets are a collection of devices connected
    via BT technology in an ad hoc fashion.
  • Each may have as many as 8 connected devices.
  • One unit acts as the master and the others as
  • Devices create many overlapping networks called
  • Formed by multiple independent and
    non-synchronized piconets.

Data Layer
  • Master device-
  • Initiates an action or requests a service.
  • Clock and hopping sequences are used to
    synchronize all other devices in the piconet.

What is 802.11
  • Wireless standards that specify an interface
    between a wireless client and a central point of
    access and among wireless clients.
  • The IEEE 802.11 specifications tailored to
    resolve compatibility issues between
    manufacturers of wireless LAN equipment.
  • The original IEEE 802.11 specifications defined
    data rates of 1 Mbps and 2 Mbps via radio waves
  • The IEEE 802.11 specifications continue to expand
    and new standards are being considered and
    ratified. The most commonly used wireless
    standard is IEEE 802.11b.

802.11 Network
802.11 a-g
  • 802.11a
  • designed to operate in the 5 GHz band.
  • Achieves data transmission rates of 54Mbps.
  • Not readily accepted overseas.
  • 802.11b
  • "High Rate" standard, also known as Wi-Fi (for
    "wireless fidelity)
  • The family of IEEE 802.11b specifications allows
    for a wireless data transmission
  • rate of 11 Mbps as an unlicensed use of the
    2.4-GHz radio frequency band.
  • 802.11g
  • The latest wireless networking specification from
  • based on 802.11b.
  • will broaden 802.11b's data rates to 54 Mbps
    within the 2.4 GHz band using OFDM (Orthogonal
    Frequency Division Multiplexing) technology.
  • IEEE 802.11g is backward compatible with IEEE

802.11 protocols contd..
  • Task Group "C"
  • improving the MAC layer to improve bridging
  • Task Group "D"
  • modifying the Physical layer to meet regulatory
    requirements around the globe.
  • Task Group "E"
  • enhance the MAC layer to improve quality of
    service (QoS) for time-sensitive applications
    like real-time voice and video.
  • Task Group "F"
  • improve interoperability of access points from
    different vendors in a distribution system.
  • Task Group "H"
  • channel selection and transmit power issues to
    ensure that 802.11a is usable in Europe, similar
    to what "D" is doing for 802.11b.
  • Some European countries currently do not allow
    802.11a, favoring the European HiperLAN2 5 GHz
    wireless LAN standard instead.
  • Task Group "I"
  • recently spun-off from Task Group "E" to put more
    emphasis on improving the security and
    authentication mechanisms.

Motivation for 802.11
  • Increased flexibility A conference with an
    ad-hoc network can be set up and dismantled in a
    short time.
  • Increased mobility Users can move around without
    restrictions and access LANs from anywhere.
  • More economical In old buildings it is more
    economical to put up some wireless stations than
    to break up walls. In factories, putting wires
    may not be feasible.

What is spread spectrum radio technology?
  • Increase reliability
  • Boost throughput
  • Allow many unrelated products (e.g., microwave
    ovens) to share the spectrum with minimal
  • 2 spread spectrum techniques
  • Frequency hopping spread spectrum (FHSS)
  • Direct sequence spread spectrum (DSSS)

What is spread spectrumradio technology?
  • FHSS
  • send a short burst of data
  • shift frequencies (hop)
  • send another short burst.
  • DSSS
  • communicate by splitting each byte of data into
    several parts
  • sending them concurrently on different
  • FHSS
  • relatively simple radio design
  • but limited to speeds of no higher than 2 Mbps
  • leads to high amount of hopping.
  • DSSS
  • uses a lot of the available bandwidth, about 22
    megahertz (MHz)
  • capable of much greater speed than FHSS since the
    devices can send a lot more data at the same

  • SSID
  • Each access point is associated with a SSID
    (service set identifier)
  • To access the network a client computer should be
    configured with the correct SSID
  • MAC
  • Each client computer has a unique MAC (Media
    Access Control) address. Each access point is
    programmed with a list of MAC addresses so it
    allows only those to associate with the AP.
  • WEP
  • Wireless transmissions are easier to intercept
    than transmissions over wired networks.
  • WEP (Wired equivalent privacy) employs the
    symmetric key encryption algorithm, Rons Code 4
    Pseudo Random Number Generator (RC4 PRNG).

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802.11 vs. Bluetooth
  • Technology
  • Bluetooth uses FHSS (Frequency Hopping Spread
    Spectrum )
  • 802.11 used FHSS and DSSS. Currently 802.11b
    uses only DSSS for higher data transfer
    capability. 802.11a and 802.11g use a Orthogonal
    Frequency Division Multiplexing (OFDM) scheme in
    the 5 and 2.4-GHz frequency range, respectively
  • Coverage
  • Bluetooth covers a personal area (PAN) the
    space of a room (up to 30 feet).
  • 802.11specifications provide coverage for local
    area networks (LANs) an office building or
    parts of a campus using multiple access points
    (APs). Each AP has a range of up to 300 feet.

Cellular Phone Systems
  • TDMA
  • FDMA
  • CDMA
  • Cell Phones Generations
  • Specifications
  • Improvements
  • Future Plans

Frequency Division Multiple Access(FDMA)
Each user is assigned one frequency to
transmit. Example AMPS
W Hz
User 4
User 3
User 2
User 1
T sec
Time Division Multiple Access(TDMA)
W Hz
User 1
User 2
User 3
User 4
T sec
Several users transmit at the same frequency but
in different time slots. Example GSM and
IS-136 Used by ATT and T-Mobile
Code Division Multiple Access(CDMA)
  • Each user transmits all the time over all the
    frequency band, but has a different spreading
  • The base station differentiates users based on
    their codes.
  • Example IS-95 (cdmaOne)
  • Used by Sprint and Verizon

Code 1
Code 2
Code 3
Code 4
CDMA Pros Cons
  • Advantages
  • Interference rejection
  • Provides security / privacy
  • Simple to add users to system
  • Greater coverage with fewer cell sites
  • Disadvantages
  • Near-Far Problem
  • Solution ?

Frequency Reuse
FDMA TDMA Need frequency planning Adjacent
cells ? Different Frequencies
CDMA NO need for frequency planning Adjacent
cells ? Same freq. Separated by code channels
The Near-Far Problem
  • Nearby mobiles ? strong signal
  • Far away mobiles ? weak signals

Power Control in CDMA
  • Mobiles adjust power at which they transmit.
  • Base station receives all signals at the
    appropriate power.
  • The CDMA network independently controls the power
    at which each mobile transmits.
  • Extra advantage Extended battery life

Generations of Cell Phones
AMPS 1983
GSM 1992 IS-95 1993 IS-136 1996
cdma2000 2002 WCDMA 2002
Higher data rates for integration of mobile
multimedia services
Comparison of variouscellular standards
Name Year Originated Multiple Access Data Rate
  Introduced From Scheme  
AMPS 1983 US FDMA 19.2 kbps
GSM 1992 Germany TDMA 22.8 Kbps
IS-136 1996 US TDMA 13 Kbps
IS-95 1993 US CDMA 19.2Kbps
cdma2000 2002 US CDMA up to 2.07 Mbps
WCDMA 2002 Europe CDMA up to 2.04 Mbps
Generations of Cell Phones
  • 1G
  • Phones are only capable of making and receiving
    voice calls.
  • 2G
  • Phones can receive and send pieces of data
  • E-mails, Web pages, etc
  • Updated versions of TDMA and CDMA allow features
    like caller ID and SMS (short message service)
  • 3G
  • Phones can receive and send both voice and data,
    but at speeds of about 144kbps, which is similar
    to what a broadband Internet connection offers PC
  • Current applications under development include
    geo-location capabilities using Global
    Positioning Systems (GPS), audio and video
    streaming, and other types of entertainment.

Goals of 3G
  • Rates
  • 2 Mbps in fixed applications
  • Up to 384 Kbps when a device is moving at
    pedestrian speed
  • 128 Kbps in a car
  • Offer services like
  • Increased Bandwidth
  • Wireless voice
  • Video
  • Email
  • Web browsing
  • Videoconferencing

Goals of 4G
  • Enable mobile phones to be a combined
  • Camera
  • Video camera
  • Computer
  • Stereo
  • Radio

CDMA Experiment
  • Equipment
  • PN Code Generator
  • Carrier Frequency
  • Oscilloscope
  • Antennas (Transmitter Receiver)
  • Signal source
  • Computers with LAWN software
  • Objectives
  • Understand concept of CDMA
  • Understand how PN code generator works
  • Demonstrate jamming / interference

  • Future for Bluetooth and 802.11
  • Can they coexist?
  • 802.11 ? Mobile LAN access
  • Long term Bluetooth will be built in.
  • Currently User has to choose between the two
  • Bluetooth is cheap!!!
  • 802.11e may have been designed to combat with
  • Frequency hopping

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  • Cellular Phone Systems
  • CDMA ? wider bandwidth, power efficient,
    interference rejection, security, more
    users. BUT Near-Far Problem !
  • Solution Power Control
  • TDMA ? Mostly used in Europe, partially in the US
    (ATT and T-Mobile)
  • FDMA ? Previously used by AMPS (1G)
  • Generations of cell phones (1G to 4G)
  • Higher data rates, more multimedia features
  • Experiment
  • PN Code generator, Frequency Jamming

  • a, b, e, and g--What 802.11 means to me (and you,
    too), David Coursey, Executive Editor, AnchorDesk
  • L.M. Correia and R. Prasad, An Overview of
    Wireless Broadband Communication, IEEE
    Communication Magazine, Jan. 1997, pp.28-33
  • Naveen Chandran and Matthew C. Valenti, Three
    generations of cellular wireless systems
  • http//
  • http//
  • Bluetooth versus 802.11, Nick Hunn, TDK Systems,
  • http//
  • maintained by
    Karen E. Peterson and Caroline Scarborough
  • http//, lecture
    by Pravin Bhagwat, ReefEdge Inc.
  • http//
  • http//
  • http//