Bluetooth, IEEE 802.11 & Cell Phone

Systems

--Arun Radhakrishnan--Thierry Fernaine

--Vipul Gautam

Overview 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

Schedule

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, FDMA) 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, PDA’s, notebook computers, fax machines

Bluetooth

Bluetooth

Low power link Short time data transfers Small indoor distances

Line of Sight is not required Better than IR link

Bluetooth Specification Protocol Stack:

Bluetooth

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 hops 10 different types of hopping sequences are

defined 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).

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.

Frequency Hopping

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 slaves.

Devices create many overlapping networks called Scatternets. 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 IEEE 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 802.11b.

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 interference.

2 spread spectrum techniques:Frequency hopping spread spectrum (FHSS)Direct sequence spread spectrum (DSSS)

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 frequencies

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 time.

What is spread spectrumradio technology?

Security 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 SSIDMAC:

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, Ron’s Code 4 Pseudo Random Number Generator (RC4 PRNG).

802.11 vs. BluetoothTechnology: 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)

T sec

Time

Frequency

W Hz

User 1

User 2

User 3

User 4

Each user is assigned one frequency to transmit.

Example: AMPS

T sec

Time

Frequency

W Hz

User 1 User 2 User 3 User 4

Time Division Multiple Access(TDMA)

Several users transmit at the same frequency but in different time slots.

Example: GSM and IS-136

Used by AT&T and T-Mobile

Code Division Multiple Access(CDMA)

Code 1

Code 2

Code 3

Code 4

• Each user transmits all the time over all the frequency band, but has a different “spreading code”.

• The base station differentiates users based on their codes.

• Example: IS-95 (cdmaOne)

• Used by Sprint and Verizon

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 & TDMANeed frequency planningAdjacent cells Different Frequencies

CDMANO need for frequency planningAdjacent 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

1stGeneration

2nd Generation

Third Generation

Fourth Generation

AMPS: 1983

GSM: 1992IS-95: 1993IS-136: 1996

cdma2000: 2002 WCDMA: 2002

Higher data rates for integrationof mobile multimedia services

Name Year OriginatedMultiple

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

Comparison of variouscellular standards

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 users.

• Current applications under development include geo-location capabilities using Global Positioning Systems (GPS), audio and video streaming, and other types of entertainment.

Generations of Cell Phones

Goals of 3G

Offer services like: Increased Bandwidth Wireless voice Video Email Web browsing Videoconferencing

Rates• 2 Mbps in fixed applications• Up to 384 Kbps when a device is moving at pedestrian speed• 128 Kbps in a car

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

Objectives:

• Understand concept of CDMA• Understand how PN code generator works• Demonstrate jamming / interference

• Antennas (Transmitter & Receiver)• Signal source• Computers with LAWN software

Summary

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 technologies.

Bluetooth is cheap!!!

802.11e may have been designed to combat with Bluetooth. Frequency hopping

Summary

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 (AT&T and T-Mobile) FDMA Previously used by AMPS (1G)

Generations of cell phones (1G to 4G) Higher data rates, more multimedia features available

Experiment PN Code generator, Frequency Jamming

References

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://www.qualcomm.com/ http://www-2.cs.cmu.edu/~dpwu/books/EE Bluetooth versus 802.11, Nick Hunn, TDK Systems, www.cellular.co.za

http://www.palowireless.com www.10meters.com/blue_802.html maintained by Karen E. Peterson and Caroline

Scarborough http://www.hoti.org/hoti9_tutorial.html, lecture by Pravin Bhagwat, ReefEdge Inc. http://grouper.ieee.org/groups/802/11/main.html http://www.utexas.edu/its/wireless/faqs/#80211 http://www.oreillynet.com/pub/a/wireless/