WIFI Introduction

Wi-Fi - an Overview

Wireless LAN - Wi-Fi

Wi-Fi (wireless fidelity) is a specification for ensuring interoperability, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access. Wi-Fi is a trademark of the non-profit Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing.

Versions – old and new Notations (view also Table besides)

The different versions of Wi-Fi are specified by various IEEE 802.11 protocol standards, with the different radio technologies determining radio bands, and the maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the 2.4 gigahertz and 5 gigahertz radio bands; these bands are subdivided into multiple channels (see figures below). Channels can be shared between networks but only one transmitter can locally transmit on a channel at any moment in time. As Wi-Fi implements CSMA/CA/listen before talk propability of collisions on the same channel can be minimized, but they cannot be reduced to p = 0.

2.4GHz Channels

5GHz Channels

Range and Power

Wi-Fi‘s wavebands have relatively high absorption and work best for line-of-sight use. Many common obstructions such as walls, pillars, home appliances, etc. may greatly reduce range, but this also helps minimize interference between different networks in crowded environments. An access point (or hotspot) often has a range of about 20 metres indoors while some modern access points claim up to a 150-metre range outdoors. Over time the speed and spectral efficiency of Wi-Fi have increased. As of today: (802.11ax -> up to 11 Gbit/s), at close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s (gigabit per second).

Connection

There are two modes in which Wi-Fi networks can operate. In the infrastructure mode, an access point acts as a central entity serving several connected clients. To connect to such a Wi-Fi network, a user typically needs the network name (the SSID) and a password. The password is used to encrypt Wi-Fi packets to block eavesdroppers. The most common security method is Wi-Fi Protected Access (WPA) which is intended to protect information moving across Wi-Fi networks and includes versions for personal and enterprise networks.

The Wi-Fi direct mode offers a point-to-point connection without the need for a dedicated central entity. The trick with Wi-Fi direct is – one of the two will be the central one on the peripheral entity (autonegotiated) so there is a central entity!

If you want to read more find here the whole Product Guide.