Technical Notes

Wireless LAN

Global Standarlization of Wireless LAN

Wireless LAN is growing rapidly by brand-new silicon devices and wireless technology revolution. This market and technology are one of the hot topics in the world. Blue-Tooth is the first product of wireless functions. However the IEEE802.11, an international standard, is the basic standard of wireless LAN in the market today. IEEE stands for Institute of Electrical and Electronics Engineers, Inc. in USA and 802 comes from the established date of February(2) 1980, 11 is 11th.

Introduction to IEEE801.11 Series

Table 1 shows the several types of wireless LAN. The 802.11b is a major type in the current market. However a bandwidth is 2.4Ghz as same as blue-tooth and other electrical stuff, so it has contention problem. The 802.11a uses OFDM technology for high-speed data transferring. In addition it uses 5.2Ghz so that it has not any contention problem. But it is not compatible as 802.11b. The 802.11g is compatibility with both 802.11b and 802.11a. Also high speed data transferring is possible by using OFDM technology.

Table 1 : Types of Wireless LAN
Type	Data Rate	RF Frequency	Modulation
Blue Tooth	1Mbps ∼ 2Mbps	2.4GHz	FHSS
IEEE802.11b	11Mbps	2.4GHz	DS, CCK
IEEE802.11a	54Mbps	5.2GHz	OFDM
IEEE802.11g	22Mbps	2.4GHz	DS, CCK, OFDM

Specification of the IEEE802.11a

R1 ∼ R4 in Signal	1101	1111	0101	0111	1001	1011	0001	0011
Data rate	6Mbps	9Mbps	12Mbps	18Mbps	24Mbps	36Mbps	48Mbps	54Mbps
Modulation	BPSK	BPSK	QPSK	QPSK	16QAM	16QAM	64QAM	64QAM
Coding rate	1/2	3/4	1/2	3/4	1/2	3/4	2/3	3/4
# of Sub Carriers	52
# of Pilots	4
OFDM Symbol Duration	4µs (effective symbol = 3.2µs)
Guard Interval	0.8µs
Sub Carrier Spacing	312.5kHz = 1/3.2µs
Sampling CLK	20MHz(50ns)

Block Diagram of the Example of the IEEE802.11a

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Magna's Direction

Magna Design Net is developing OFDM IP core of IEEE802.11 series for wireless LAN. Please check out our product lineup!

Products of Wireless LAN