Wifi Technology & History

1. History ofWiFi
Iwan Handoyo Putro

2. History ofWiFi

3. Radio
• Heinrich Rudolf Hertz made the first properly documented
transmissions of electromagnetic waves in the 1880s. Later,
of course, Hertz became the very name of the unit for
measuring frequencies.
• In the 1890s, Bose famously demonstrated microwaves by
using them to ignite gunpowder and ring a bell at a
distance, in front of an audience in the town hall of
Kolkata.
• In his essay "Invisible Light", Bose wrote:
The invisible light can easily pass through brick
walls, buildings etc. Therefore, messages can be
be transmitted by means of it without the
mediation of wires.
• Towards the turn of the century, Guglielmo
Marconi introduced the first commercially usable
apparatus for wireless long-distance telegraphy–building
on the work of, among others, Hertz, Tesla, and Bose.

4. Tesla
• Nikola Tesla was also behind the first known
method for changing frequencies to avoid
interference. In 1903 he patented a system where
the transmitter and the receiver switch
synchronously between two channels.
• Like any ground breaking communication
technology this, too, soon found a military use.
From 1915, the German military started using
radios with changing frequencies to prevent the
British from eavesdropping.

5. Hedy Lamarr
• Hollywood star Hedy Lamarr was sharp, inventive, and had a decidedly
wide range of interests. She was the one who would come to take this
technology further.
• She developed her contribution to Wi-Fi history together with avant garde
composer George Antheil, who had referred to himself as "the bad boy of
music".
• Lamarr was familiar with both radio technology and the weapons industry.
She knew that torpedoes were effective weapons, but highly vulnerable to
the detection and sabotage of the radio signals used to control them. She
had the idea of using multiple, changing frequencies to make signal
sabotage harder, and referred to it as frequency hopping. This is an early
example of what is now known as spread spectrum technology.
• However, the American navy proved unenthusiastic about the proposed
apparatus for making use of this system, and so did not adopt it at the
time. Only much later, after the original patent had expired, someone finally
put their invention to use for military purposes.
• In 1997, the Electronic Frontier Foundation (EFF) awarded Lamarr and
Antheil (posthumously) their Pioneer Award for the inventors' "trail-blazing
development of a technology that has become a key component of
wireless data systems".

6. ALOHAnet
• Packet radio is a radio communication technology that sends data as
packets. The first packet radio network was developed at the University of
Hawaii in 1971. ALOHAnet connected seven campuses on four different
islands, ensuring that they could all communicate with each other through
a central computer located on the island of Oahu. The group that
developed the network was headed by Professor Norman Abramson.
• ALOHAnet also gained interest with the US military and DARPA (Defense
Advanced Research Projects Agency), who came to develop multiple
networks based on packet radio, for tactical field communication usage,
among others. This was during the same time that DARPA was developing
ARPANET, now known as the predecessor of the internet.
• Packet radio networks gained some traction in the private market as well,
but was never a commercial success–transmission speeds were too low,
costs were too high, and the selection too small. Today, amateur/HAM
radios are the most common use for packet radio.
• Many manufacturers opted for the cabled Ethernet technology, that was
available from the early 80s, rather than the slow and expensive packet
radio. Soon, brand new wireless possibilities were to open up.

7. Victor Hayes
• His role in establishing and chairing the IEEE 802.11 Standards
Working Group for Wireless Local Area Networks has led to him
being referred to by some as the "Father of Wi-Fi"
• The real shift happened in the late 1990s, when Vic Hayes—known to
many as the “father of WiFi”—introduced the concept of an
international standard for wireless networking, known as the IEEE
802.11 standard.
• In 1999, Hayes and his team at the Institute of Electrical and
Electronics Engineers (IEEE) updated the standard for WiFi to 802.11b.
This essentially expanded the technology outside of the halls of
academic institutions and into the homes of everyday consumers. Of
course, IEEE 802.11b was quite a mouthful for the everyday internet
user, so the committee brought in a branding firm to rename the
technology. “WiFi” was the ultimate winner over suggestions like
“Trapeze,” “Hornet,” and “Dragonfly.” The same year, the WiFi
Alliance was established to ensure WiFi kept the same set of
standards across the globe.

8. Garbage Bands
• In 1985, FCC, the US telecommunication authorities, chose to open up three frequency bands on the wireless
spectrum for unlicensed use.
• Those bands, also known as "the garbage bands", were 900MHz, 2.4 GHz, and 5.8 GHz.
• These bands were already in use for, among other purposes, microwave ovens, that cook food using radio waves.
The condition for using these bands for communication purposes, was therefore being able to work around
interference from other equipment using spread spectrum technology – such as frequency hopping.
• Vendors quickly started developing their own, proprietary solutions that communicated using these frequencies.
While some of them worked just fine on their own, the obvious weakness was the lack of communication across
solutions.

9. TheOrigin ofWi-Fi
• Technical standards are voluminous documents. Once people start implementing
these standards, they often interpret them differently, and this happened with the
802.11 standard, too.
• In 1999, six major vendors therefore founded a new industry alliance to improve
cross compatibility.
• The new alliance had a great cause, but they were in need of a good name, both
for themselves and for the standards they were going to promote. They hired
branding consultants to find a name that was "a little more catchy than 'IEEE
802.11b Direct Sequence'".
• The consultants proposed "Wi-Fi" as a riff on "hi-fi", borrowed from the world of
music. No, it was never meant to be an acronym or abbreviation. Wi-Fi is in fact
not short for anything at all, despite the occasional unsuccessful attempt to
introduce such terms as "wireless fidelity".
• The term "Wi-Fi" itself, however, caught on quickly, and it stuck.
• The new industry association became the Wi-Fi Alliance, and today hundreds of
technology vendors are part of this alliance. The alliance promotes wireless
technology, protects "Wi-Fi" as a brand and seal of approval, and certifies wireless
products.
• When it comes to developing the standards, however, IEEE committee 802.11 is still
in charge.

10. Frequency HoppingVs. DirectSequence
• FH systems use a radio carrier that “hops” from frequency to frequency in a
pattern known to both transmitter and receiver
• Easy to implement
• Resistance to noise
• Limited throughput (2-3 Mbps @ 2.4 GHz)
• DS systems use a carrier that remains fixed to a specific frequency band. The
data signal is spread onto a much larger range of frequencies (at a much
lower power level) using a specific encoding scheme.
• Much higher throughput than FH (11 Mbps)
• Better range
• Less resistant to noise (made up for by redundancy – it transmits at
least 10 fully redundant copies of the original signal at the same time)

11. Frequency HoppingVs. DirectSequence

12. Frequency HoppingVs. DirectSequence

13. What isWi-Fi?

14. Wi-FiAlliance
• Non-profit standards organization.
• Global organization that created the
Wi-Fi brand name.
• Formerly the Wireless Ethernet
Compatibility Alliance.
• Wi-Fi is a trademark of the non-
profit Wi-Fi Alliance, which restricts
the use of the term Wi-Fi Certified to
products that successfully
complete interopera-
bility certification testing.

15. Wi-FiCertification
• The Wi-Fi CERTIFIED logo from the Wi-Fi Alliance.
• Rigorous interoperability testing requirements.
• Certifies the interoperability of 802.11 products from the many
different vendors.

16. Enter Standardization
• Vendors therefore slowly came to see the need for a shared wireless standard, much
like Ethernet had become a successful industry standard for wired network communication.
• A committee of the organization Institute of Electrical and Electronics Engineers
(IEEE) develops the Ethernet standard, and so the vendors contacted IEEE to discuss the
possibility of forming a brand new standards committee for wireless communications.
• The new committee started work in 1990 under the catchy name "802.11". This number
remains a part of the name of every standard the committee releases.
• The committee finally agreed on and released the first of those standards in 1997. The first
802.11 standard used frequency hopping and provided a data transfer capacity of 2
megabit per second.
• New and improved versions of the standard came out fairly frequently in the years that
followed. In newer standards, direct sequence—a different spread spectrum technology—
also replaced frequency hopping.

17. A Brief IEEE 802.11Standard

18. IEEE 802.11 Frequency andSpeed

19. 802.11 -Transmission
• Most wireless LAN products operate in
unlicensed radio bands
• 2.4 GHz is most popular
• Available in most parts of the world
• No need for user licensing
• Most wireless LANs use spread-spectrum radio
• Resistant to interference, secure
• Two popular methods
• Frequency Hopping (FH)
• Direct Sequence (DS)

20. Hardware
• PC Card, either with integral antenna or with
external antenna/RF module.
• ISA Card with external antenna connected by
cable.
• Handheld terminals
• Access points
• PCMCIA card
• USB WiFi-based
• Express card

21. Hardware
Wireless Extender
WiFi Outdoor Antenna
PCMCIA Card
Wireless Router
Wireless USB
Access Point

22. Advantages
• Freedom – You can work from any location that
you can get a signal.
• Setup Cost – No cabling required.
• Flexibility – Quick and easy to setup in temp or
permanent space.
• Scaleable – Can be expanded with growth.
• Mobile Access – Can access the network on the
move.

23. Disadvantages
• Speed – Slower than cable.
• Range – Affected by various medium.
• Travels best through open space.
• Reduced by walls, glass, water, etc
• Security – Greater exposure to risks.
• Unauthorized access.
• Compromising data.
• Denial of service.

24. 802.11a
• Employs Orthogonal Frequency Division
Multiplexing (OFDM)
• Offers higher bandwidth than that of 802.11b, DSSS
(Direct Sequence Spread Spectrum)
• 802.11a MAC (Media Access Control) is same as
802.11b
• Operates in the 5 GHz range

25. 802.11aAdvantages
• Ultra-high spectrum efficiency
• 5 GHz band is 300 MHz (vs. 83.5 MHz @ 2.4 GHz)
• More data can travel over a smaller amount of
bandwidth
• High speed
• Up to 54 Mbps
• Less interference
• Fewer products using the frequency
• 2.4 GHz band shared by cordless phones, microwave ovens,
Bluetooth, and WLANs

26. 802.11a Disadvantages
• Standards and Interoperability
• Standard not accepted worldwide
• No interoperability certification available
for 802.11a products
• Not compatible or interoperable with 802.11b
• Legal issues
• License-free spectrum in 5 GHz band not
available worldwide
• Market
• Beyond LAN-LAN bridging, there is limited interest
for 5 GHz adoption

27. 802.11a Disadvantages
• Cost
• 2.4 GHz will still has >40% cost advantage
• Range
• At equivalent power, 5 GHz range will be ~50% of 2.4
GHz
• Power consumption
• Higher data rates and increased signal require more
power
• OFDM is less power-efficient then DSSS

28. 802.11aApplications
• Building-to-building connections
• Video, audio conferencing/streaming video,
and audio
• Large file transfers, such as engineering
CAD drawings
• Faster Web access and browsing
• High worker density or high throughput
scenarios
• Numerous PCs running graphics-intensive
applications

29. 802.11aVs. 802.11b
802.11a vs.
802.11b
802.11a 802.11b
Raw data rates Up to 54 Mbps
(54, 48, 36, 24,18, 12
and 6 Mbps)
Up to 11 Mbps
(11, 5.5, 2, and
1 Mbps)
Range 50 Meters 100 Meters
Bandwidth UNII and ISM
(5 GHz range)
ISM (2.4000—
2.4835 GHz range)
Modulation OFDM technology DSSS technology

30. 802.11g
• 802.11g is a high-speed extension to 802.11b
• Compatible with 802.11b
• High speed up to 54 Mbps
• 2.4 GHz (vs. 802.11a, 5 GHz)
• Using OFDM for backward compatibility
• Adaptive Rate Shifting

31. 802.11gAdvantages
• Provides higher speeds and higher capacity
requirements for applications
• Wireless Public Access
• Compatible with existing 802.11b standard
• Leverages Worldwide spectrum availability
in 2.4 GHz
• Likely to be less costly than 5 GHz alternatives
• Provides easy migration for current users of 802.11b
WLANs
• Delivers backward support for existing 802.11b products
• Provides path to even higher speeds in the future

32. 802.11e IntroducesQuality of Service
• Also know as P802.11 TGe
• Purpose:
• To enhance the 802.11 Medium Access
Control (MAC) to improve and manage
Quality of Service (QoS)
• Cannot be supported in current chip design
• Requires new radio chips
• Can do basic QoS in MAC layer

33. 802.11f – InterAccess Point Protocol
• Also know as P802.11 TGf
• Purpose:
• To develop a set of requirements for Inter-Access
Point Protocol (IAPP), including operational and
management aspects

34. 802.11bSecurity Features
• Wired Equivalent Privacy (WEP) – A protocol to
protect link-level data during wireless transmission
between clients and access points.
• Services:
• Authentication: provides access control to the network by
denying access to client stations that fail to authenticate
properly.
• Confidentiality: intends to prevent information
compromise from casual eavesdropping
• Integrity: prevents messages from being modified while in
transit between the wireless client and the access point.

35. Pros IEEE 802.11n
• Faster. Thanks to 5 GHz band.
• Less Prone to Interference
• You may never have any problems with WiFi interference. But as
more and more wireless devices come along, especially in the
2.4GHz frequency band, the risk of interference increases.
• Latest security features
• The 802.11n standard specifies Wi-Fi Protected Access 2 (WPA2)
and allows for the data to be encrypted using the NIST Advanced
Encryption Standard (AES).
• Ready for next generation multimedia
• The 802.11n standard has been designed to support an anticipated
demand for access to more data faster as new generation devices
connect to existing networks and activities such as high speed
interactive gaming and streaming music and video become more
common.

36. Cons IEEE 802.11n
• More expensive compared to previous standards
• use of multiple signals may interfere with nearby
802.11b/g based networks

37. Pros IEEE 802.11ac
• The most obvious benefit of 802.11ac is in the speed bump gained
when compared to 802.11n.
• More reliable long-range transmissions
• Working in areas with multiple obstructions
• Backward compatibility
• Improved multi-user performance
• More channel bonding choices
• is the process of combining multiple channels together to create a
longer-width channel that can transmit higher bandwidths.
• 256 QAM modulation
• In 802.11n, the modulation used is 64-QAM. 802.11ac packs in more
information by using 256-QAM.

38. Cons IEEE 802.11ac
• More expensive.
• 2.4 GHz band is not supported.
• Speed and Performance of device can vary for
different devices.

39. Security Problems
• Security features in Wireless products are frequently
not enabled.
• Use of static WEP keys (keys are in use for a very
long time). WEP does not provide key management.
• Cryptographic keys are short.
• No user authentication occurs – only devices are
authenticated. A stolen device can access the
network.
• Identity based systems are vulnerable.
• Packet integrity is poor.

40. OtherWLANSecurity Mechanisms
• 3Com Dynamic Security Link
• CISCO LEAP - Lightweight Extensible Authentication
Protocol
• IEEE 802.1x – Port-Based Network Access Control
• RADIUS Authentication Support
• EAP-MD5
• EAP-TLS
• EAP-TTLS
• PEAP - Protected EAP
• TKIP - Temporal Key Integrity Protocol
• IEEE 802.11i

41. Access Point Placement and Power
• Typically – mounted at ceiling height.
• Between 15 and 25 feet (4.5m to 8m)
• The greater the height, the greater the difficulty
to get power to the unit. Solution: consider
devices that can be powered using CAT5
Ethernet cable (CISCO Aironet 1200 Series).
• Access points have internal or external antennas

42. AntennaSelection and Placement
• Permanently attached.
• Remote antennas connected using an antenna
cable.
• Coax cable used for RF has a high signal loss,
should not be mounted more than a 1 or 2
meters away from the device.
• Placement: consider building construction,
ceiling height, obstacles, and aesthetics. Different
materials (cement, steel) have different radio
propagation characteristics.

43. Connecting to theWired LAN
• Consider user mobility
• If users move between subnets, there are challenges to
consider.
• OSes like Windows XP and 2000, Linux support DHCP to
obtain the new IP address for the subnet. Certain
applications such as VPN will fail.
• Solution: access points in a roaming area are on the
same segment.