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02/03/2012

WLAN/Wi-Fi

In this page: Definition, applications, standards and frequencies for Wireless LAN (WLAN), also known as Wi-Fi.

WLAN/Wi-Fi

Hot-spots Wi-Fi in Brazil

Thousands	2008	2009	2010	2011	Jan/12
São Paulo	2,733	2,446	2,455	2,560	2,563
Rio de Janeiro	395	460	454	487	488
Paraná	130	150	155	163	164
Distrito Federal	153	156	151	154	155
Rio Grande do Sul	110	134	136	144	148
Minas Gerais	93	89	91	107	107
Total Brazil	4,090	3,982	3,997	4,196	4,209

Source: JiWire.

Research carried out by NIC.br shows that 28% of the companies have wireless nets. In 2006 it was 17%.

Hot-spots Wi-Fi in the world

Thousands	2009	2010	2011	Jan/12
United Kingdom	27,877	26,516	181,788	181,661
China	35,115	102,283	110,571	110,640
United States	68,609	93,299	103,843	103,882
South Korea	12,815	26,885	83,642	83,644
France	26,272	30,834	35,063	35,049
Germany	14,738	14,752	23,24	24,105
Russia	14,701	14,674	16,679	16,675
Total in more than 140 countries	287,992	414,835	687,423	689,211

Source: site JiWire.

Wi-Fi

A Wireless LAN (WLAN) is a local net wireless standardized by IEEE 802.11. It's also known as Wi-Fi, abbreviation of "wireless fidelity" and registered brand owned by Wireless Ethernet Compatibility Alliance (WECA).

Main applications

Local Internal Net of offices and houses, replacing or complementing nets which use coaxial cables.
Public Nets for internet access, for those the Wi-Fi name is more used.

Standards

The IEEE 802 Committee, "Institute of Electrical and Electronics Engineers" from the United States, is a group that leads the standardization of local nets (LANs) and Metropolitans (MANs) in worldwide level.

The initial standard 802.11 of 1999 was improved being defined currently the following alternatives:

	Frequencies	Technical Modulation	Date Index
802.11b	2400-2483,5 MHz	DSSS	until 11 Mbit/s**
802.11g	2400-2483,5 MHz	DSSS, OFDM	until 54 Mbit/s
802.11a	5150-5350 MHz 5470-5725 MHz* 5725-5850 MHz	OFDM	until 54 Mbit/s

* O IEEE 802.11h extends this standardo

**There is an attachment to this rule which permits to extend the index until 44 Mbit/s.

The major part of the Brazilian nets use the 802.11b standard.

Technical Modulation

DSSS (Direct Sequence Spread Spectrum) is the spectrum spread by direct sequence.

OFDM (Orthogonal Frequency Division Multiplexing) is a more efficient technique of modulation than DSSS.

Available frequencies in Brazil

The WiFi nets use frequencies that have no need of authorization to be used.

The conditions of use to this frequencies in Brazil are established by the Regulation on Equipments of Radio Communication of Radiation (Regulamento sobre Equipamentos de Radiocomunicação de Radiação Restrita. sections IX and X - in Portuguese), reedited by Anatel's resolution 365 of 05/10/04.

Frequencies (MHZ)

Conditions of use in Brazil

2400-2483

5725-5850

Destined in Brazil, in second character, to equipments of Restricted Radio Communication like Wi-Fi nets and Radio Spread Spectrum.

The band of 2400 MHz is used in Brazil in primary characyer by "Serviço Auxiliar de Radiodifusão e Correlatos - SARC" and for Repetition in TV.

Anatel established that systems (2400 MHz) places, where the population is higher than 500 thousand inhabitants and potency (eirp) higher than 400 mW, can't operate without Anatel's authorization.

5150-5350

5470-5725

Wireless Access Systems in Broadband to local nets.

Band 5150-5350 MHz can be used in internal environments (indoor) and 5470-5725 MHz in external and internal environments.

Other standards of IEEE 802

IEEE 802 has other standards for wireless nets like Wireless Personal Area Network (WPAN) which includes 802.15.1 (Bluetooth) and 802.16 Broadband Wireless Access (BBWA) or WiMax.