What is WiFi
Wi-Fi, or WiFi, is a wireless LAN technology that uses devices that are based on IEEE 802.11 standards. WiFi is a brand of the WiFi Alliance. It limits the use of the term WiFi Certified to products that pass the interoperability certification tests. Devices that can use WiFi technology are quite varied. We also have computers, game consoles, smartphones; but also tablets, digital cameras, smart TVs, digital audio players, etc. WiFi enabled devices can connect to the internet via a WLAN and a wireless access point. Access point, or hotspot, has a range between 10 meters to 30 meters indoors and it can have a greater reach outdoors.
Australian radio astronomer John O’Sullivan and colleagues Terence Percival, Graham Daniels, Diet Ostry and John Deane have developed a key patent for WLAN technology. This patent comes from “a failed experiment to detect the explosion of mini-black holes the size of an atomic particle.” Dr. O’Sullivan and his colleagues have somehow invented WiFi. In 1992 and 1996, CSIRO obtained patents for a method later used in WiFi to “not broadcast” the signal. The first version of the 802.11 protocol was released in 1997. It achieves link speeds of up to 2 Mbit / s. This was updated in 1999 with 802.11b to achieve link speeds of 11 Mbit/s.
Evolution of the WiFi Alliance
In 1999, the Wi-Fi Alliance became a trade association in order to own the Wi-Fi brand property; under which most products are sold. WiFi uses a large number of patents owned by many different organizations. In April 2009, 14 companies agreed to donate $ 1 billion to CSIRO for CSIRO patent infringements. This led Australia to qualify the Australian invention’s WiFi; although this has been controversial. CSIRO won another legal victory in 2012 and earned $ 220 million for WiFi patent infringement; companies in the United States to pay CSIRO license fees. These fees were estimated at $ 1 billion in additional royalties.
IEEE does not test equipment for compliance with their standards. The Wi-Fi Alliance non-profit was created in 1999 to fill this void. This allows the establishment and application of interoperability and backward compatibility standards. But also to promote wireless LAN technology.
In 2010, the Wi-Fi Alliance was made up of more than 375 companies worldwide. The Wi-Fi Alliance applies Wi-Fi branding to technologies based on the IEEE 802.11 standards. This includes wireless LAN (WLAN) connections and device-to-device connectivity; the like WiFi Peer to Peer aka WiFi Direct. But also the personal area network (PAN), local area network (LAN) and even an extended area limited to network connections (WAN). Manufacturers who are members of the Wi-Fi Alliance, whose products pass the certification process, have the right to affix the Wi-Fi logo on their products.
Specifically, the certification process requires compliance with IEEE 802.11 radio standards, WPA and WPA2 security standards, and the EAP authentication standard. Then the certification may possibly include IEEE 802.11 project standards testing. As well as the interaction with cell phone technology in convergent devices and features relating to the configuration of security, multimedia and energy saving.
Not all WiFi devices are subject to certification. However, the lack of WiFi certification does not necessarily imply that a device is incompatible with other WiFi devices. The Wi-Fi Alliance may or may not sanction such drifts; such as the Super Wi-Fi, invented by the Federal Communications Commission (FCC) of the United States. This term describes the networking proposed in the UHF band in this country.
WiFi and the IEEE 802.11 standard
The IEEE 802.11 standard is a set of media access control (MAC) and physical layer (PHY) specifications for the implementation of wireless LAN (WLAN) computer communications in the 2.4 frequency bands. , 3.6, 5 and 60 GHz. They are created and maintained by the IEEE LAN / MAN Standards Committee (IEEE 802).
The basic version of the standard was published in 1997. Since then, it has undergone subsequent changes. Thus, the standard and the modifications form the basis of wireless network products using the Wi-Fi brand. However, although each amendment is formally revoked when it is incorporated in the latest version of the standard, the world of business tends to market revisions because they concisely state the capabilities of their products. Thus, on the market, each revision tends to become its own standard.
WiFi and Internet access
WiFi technology can be used to provide internet access to devices within the reach of a wireless network connected to the internet. The coverage of one or more interconnected access points (hotspots) can range from as small as a few rooms to several square kilometers.
Coverage in a larger area may require a group of access points with overlapping coverage. For example, open-air public Wi-Fi has been used successfully in wireless mesh networks in London, UK. The Fon wireless network is a good example.
WiFi is used at home as well as in businesses or public spaces. In the latter case, WiFi is set up for free or commercially. He often uses a web page giving access to a captive portal to connect. Organizations and businesses, such as airports, hotels and restaurants, often offer free hotspots to attract customers.
Routers that incorporate a digital modem or cable modem and a WiFi access point are often installed in homes and other buildings. They provide internet and inter-network access to all wireless and wired devices. Similarly, battery-powered routers may include a cellular internet radio modem and a WiFi access point. Thus, if they have a SIM card, they allow neighboring WiFi stations to access the Internet via 2G, 3G or 4G networks; using the connection-sharing technique.
Many smartphones have an integrated capacity of this type. Including those based on Android, BlackBerry, Bada, iOS, Windows Phone and Symbian. “Internet packs” also provide standalone installations of this type, without using a smartphone; for example, thanks to MiFi and WiBro devices. Some laptops with a cellular modem card also allow them to serve as Wi-Fi hotspots.
In the early 2000s, many cities around the world announced plans to deploy WiFi networks across the city. There are many successful examples. First, in 2004, Mysore became the first WiFi city in India. A company called WiFiyNet has installed hotspots in Mysore; covering the entire city and some neighboring villages. Then, in 2005, St. Cloud, Florida, and Sunnyvale, California, became the first cities in the United States to offer free WiFi throughout the city.
In May 2010, Boris Johnson, mayor of London, promised to have a London-wide WiFi network by 2012. Several districts, including Westminster and Islington, already had extensive WiFi coverage outside of London. time. Officials from the South Korean capital, Seoul, have also offered to provide free internet access in more than 10,000 locations in the city; including outdoor public spaces, main streets and densely populated residential areas. Seoul will grant concessions to KT, LG Telecom and SK Telecom. Companies will invest $ 44 million in the project.
More recently, the European Union has unveiled the WiFi4EU initiative . The goal: to install free public wireless hotspots in European municipalities that do not currently have any service or infrastructure.
Many traditional university campuses in developed countries offer at least partial WiFi coverage. For example, Carnegie Mellon University deployed the first campus-wide wireless network. Called Wireless Andrew, this network was deployed on the Pittsburgh campus in 1993; even before the appearance of the brand Wi-Fi.
In February 1997, CMU Wi-Fi was fully operational. Since then, many universities have collaborated to provide Wi-Fi access to students and staff through Eduroam’s international authentication infrastructure.
The WiFi radio spectrum
The 802.11b and 802.11g standards use the 2.4 GHz ISM band. Because of this choice of frequency band, 802.11b and 802.11g devices can sometimes be interfered with. This interference can come from microwave ovens, cordless phones and Bluetooth devices.
Frequency assignments and operational limitations are not uniform in the world. Australia and Europe allow two additional channels (12, 13); beyond the 11 allowed in the United States for the 2.4 GHz band. Finally, Japan has three others. In the United States and other countries, 802.11a and 802.11g devices may be used without a license; in accordance with FCC regulations.
A WiFi signal occupies five channels in the 2.4 GHz band. Any number of two channels that differ by five or more, such as 2 and 7, do not overlap.
The often repeated saying that channels 1, 6 and 11 are the only channels that do not overlap is therefore not accurate. Thus, channels 1, 6 and 11 are the only group of three channels that do not overlap … in North America and the United Kingdom. In Europe and Japan, it is recommended to use channels 1, 5, 9 and 13 for 802.11g and 802.11n.
802.11a uses the 5 GHz U-NII band, which in much of the world offers at least 23 non-overlapping channels. A big difference with the 2.4 GHz ISM frequency band, where adjacent channels overlap.
Service Set Identifier (SSID)
In addition to operating on different channels, several WiFi networks can share channels.
A set of services is the set of all devices associated with a particular WiFi network. The set of services may be local, independent, extended, or meshed.
Each service set has an associated identifier, the 32-bit Service Set Identifier (SSID); which identifies the particular network. The SSID is configured in devices considered to be part of the network. It is transmitted in packets. Receivers ignore wireless packets from networks with a different SSID.