1. LEBÉE Marie-Hélène PERALTA Philippe A1B IEEE 802.11j standard

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

3. How we have worked We have organised the work in four parts: -research-reading-selection-redaction We have separated the work in two between us

4. 1. Presentation of Wi-Fi 2. The 802.11 standard 2.1 The OSI model 2.2 The physical layer 2.2 The physical layer 2.3 The data link layer 2.3 The data link layer 2.3.1 LLC 2.3.2 MAC 3. The different specifications of the 802.11 standard 4. The 802.11j standard 4.1 The particular case of Japan 4.1 The particular case of Japan 4.2 Modulation technique for transmission: OFDM 4.2 Modulation technique for transmission: OFDM 5. Conclusion

5. Presentation of Wi-Fi Presentation of Wi-Fi Technology of WLAN is based on the IEEE 802.11 specifications Firstly created for internal networks Used for Internet access, gaming, and basic connectivity of consumer electronics

6. The 802.11 standard

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

8. The physical layer The physical layer Provides the means of transmitting raw bits Performs services requested by the data link layer Defines all the electrical and physical specifications for devices

9. The data link layer The data link layer Transfers data between adjacent network nodes Provides the functional and procedural means to transfer data Provides the means to detect and possibly correct errors that may occur in the physical layer May be split into a MAC layer and a LLC layer

10. The most important specifications The most important specifications In 1999 two extensions to 802.11 were 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: 802.11g (2.4 GHz, 54 Mbps) 802.11g (2.4 GHz, 54 Mbps) 802.11j is an extension of 802.11a

11. The 802.11j standard

12. The particular case of Japan 802.11j was: Finalized in 2004 Finalized in 2004 Elaborated specially for the Japanese market Elaborated specially for the Japanese market Works in a band of frequencies centered around 5 GHz to conform to the Japanese rules

13. Modulation technique for transmission: OFDM Orthogonal frequency-division multiplexing Divides the available spectrum into 52 orthogonal sub-carriers OFDM modulation and demodulation are typically implemented using digital filter banks generally using the Fast Fourier Transform (FFT).

14. Difficulties we have met Documents were hard to find Some documents were too technical

15. Conclusion The complexity of access to the licenses on the 5 GHz band in Japan did not make 802.11a standard popular as much as expected So, a new specification 802.11j appeared, with a limitation at 4.9 GHz Finally if the access to the 2.4 GHz and 5 GHz on the same peripheral requires a technological adaptation, the operation is simplified between the 4.9 GHz and 5 GHz, which makes it possible to develop peripherals which will accept the two frequencies without rupture

16. The end Thank you for your attention! Thank you for your attention!