LEBÉE Marie-HélèneLEBÉE Marie-HélènePERALTA PhilippePERALTA PhilippeA1BA1B

IEEE 802.11j standardIEEE 802.11j standard

Why this subject?Why this subject?

Wireless technologies are more and more Wireless technologies are more and more used nowadays. The 802.11j standard is used nowadays. The 802.11j standard is relative to the technology of wireless local relative to the technology of wireless local area networksarea networks. That’s why we were That’s why we were interested on it.interested on it.

How we have workedHow we have worked

We have organised the work in four parts:We have organised the work in four parts:-research-research-reading-reading-selection -selection -redaction-redaction

We have separated the work in two We have separated the work in two between usbetween us

1. Presentation of Wi-Fi1. Presentation of Wi-Fi

2. The 802.11 standard2. The 802.11 standard2.1 The OSI model2.1 The OSI model

2.2 The physical layer2.2 The physical layer 2.3 The data link layer2.3 The data link layer

2.3.1 LLC2.3.1 LLC2.3.2 MAC2.3.2 MAC

3. The different specifications of the 802.11 standard3. The different specifications of the 802.11 standard

4. The 802.11j standard4. The 802.11j standard 4.1 The particular case of Japan4.1 The particular case of Japan 4.2 Modulation technique for transmission: OFDM4.2 Modulation technique for transmission: OFDM

5. Conclusion5. Conclusion

Presentation of Wi-FiPresentation of Wi-Fi

Technology of WLAN is Technology of WLAN is based on the IEEE 802.11 based on the IEEE 802.11 specificationsspecifications

Firstly created for internal Firstly created for internal networksnetworks

Used for Internet access, Used for Internet access, gaming, and basic gaming, and basic connectivity of consumer connectivity of consumer electronics electronics

The 802.11 standardThe 802.11 standard

The OSI modelThe OSI model

Open Systems Open Systems Interconnection Interconnection Layered abstract Layered abstract description for description for communications and communications and computer network computer network protocol designprotocol design The IEEE 802.11 The IEEE 802.11 standard defines only standard defines only the data link layer and the data link layer and the physical layerthe physical layer

The physical layerThe physical layer

Provides the means of transmitting raw Provides the means of transmitting raw bits bits

Performs services requested by the data Performs services requested by the data link layerlink layer

Defines all the electrical and physical Defines all the electrical and physical specifications for devicesspecifications for devices

The data link layerThe data link layer

Transfers data between adjacent network Transfers data between adjacent network nodes nodes Provides the functional and procedural Provides the functional and procedural means to transfer datameans to transfer dataProvides the means to detect and possibly Provides the means to detect and possibly correct errors that may occur in the correct errors that may occur in the physical layerphysical layerMay be split into a MAC layer and a LLC May be split into a MAC layer and a LLC layer layer

The most important The most important specificationsspecifications

In 1999 two extensions to 802.11 were In 1999 two extensions to 802.11 were approved:approved: 802.11a (5 GHz, 54 Mbps) 802.11a (5 GHz, 54 Mbps) 802.11b (2.4 GHz, 11 Mbps)802.11b (2.4 GHz, 11 Mbps)

In 2003:In 2003: 802.11g (2.4 GHz, 54 Mbps)802.11g (2.4 GHz, 54 Mbps)

802.11j is an extension of 802.11a802.11j is an extension of 802.11a

The 802.11j standardThe 802.11j standard

The particular case of JapanThe particular case of Japan

802.11j was:802.11j was: Finalized in 2004Finalized in 2004 Elaborated specially for the Japanese marketElaborated specially for the Japanese market

Works in a band of frequencies centered Works in a band of frequencies centered around 5 GHz to conform to the Japanese around 5 GHz to conform to the Japanese rulesrules

Modulation technique for Modulation technique for transmission: OFDMtransmission: OFDM

Orthogonal frequency-division multiplexingOrthogonal frequency-division multiplexing

Divides the available spectrum into 52 Divides the available spectrum into 52 orthogonal sub-carriersorthogonal sub-carriers

OFDM modulation and demodulation are OFDM modulation and demodulation are typically implemented using digital filter typically implemented using digital filter banks generally using the Fast Fourier banks generally using the Fast Fourier Transform (FFT).Transform (FFT).

Difficulties we have metDifficulties we have met

Documents were hard to findDocuments were hard to find

Some documents were too technicalSome documents were too technical

ConclusionConclusion

The complexity of access to the licenses on the 5 GHz The complexity of access to the licenses on the 5 GHz band in Japan did not make 802.11a standard popular band in Japan did not make 802.11a standard popular as much as expected as much as expected

So, a new specification 802.11j appeared, with a So, a new specification 802.11j appeared, with a limitation at 4.9 GHzlimitation at 4.9 GHz

Finally if the access to the 2.4 GHz and 5 GHz on the Finally if the access to the 2.4 GHz and 5 GHz on the same peripheral requires a technological adaptation, same peripheral requires a technological adaptation, the operation is simplified between the 4.9 GHz and 5 the operation is simplified between the 4.9 GHz and 5 GHz, which makes it possible to develop peripherals GHz, which makes it possible to develop peripherals which will accept the two frequencies without rupturewhich will accept the two frequencies without rupture

The endThe end Thank you for your attention!Thank you for your attention!