Introduction to WLAN

A Wireless Local Area Network (WLAN) is a Local area network where-in the endpoint devices do not connect via wires (i.e. an Ethernet Connection) to a network.  The user devices such as smart phones connect wirelessly. In most cases WLAN provides the end-point connectivity or provides a complete network in itself.

WLAN uses the Industrial, Scientific and Medical (ISM) band for WLAN operation. It shares the ISM band with other ISM band users such as Bluetooth, Near-field communcation and the original intended users of the the ISM band – the Industrial/scientific/Medical devices.

The WLAN standard is described by the Institute of Electrical and Electronics Engineers (IEEE) standard’s body via the 802.11 set of standards. Derivative standards from the 802.11 standard for various WLAN applications (such as Wi-Fi direct /Miracast etc) and Wireless LAN certification is performed by the Wi-Fi Alliance. In certain cases – the Wi-Fi alliance has come out with a set of standards for a particular WLAN use case before the IEEE standard has been designed for the same (e.g. 802.11e).   

The Two Radio Frequency Bands of operation are defined for use in WLAN – the 2.4 GHz and the 5 GHz band. 

There are two basic modes of operation defined in WLAN

                 1) Infrastructure mode – in this mode WLAN provides end-point connectivity

                 2) Ad-hoc mode – Peer to Peer connections – provides a self -sufficient wireless                          network

Infrastructure mode

The user devices (e.g smart phones) connect wirelessly to a WLAN master device (Access Point – AP). The AP would connect to a network controller (via Ethernet) which in turn would connect the wireless end-point Station device (e.g. Smart Phone) to the internet.  

FIG: A simple Infrastructure network topology

Ad-hoc mode

in Ad-hoc mode, the user devices connect to one another to form a local Peer-to-Peer self-sufficient connection. one of the devices in the network would assume the role of a master from time to time.  

FIG: A Simple Ad-hoc Mode Topology

Ad-hoc mode operation did not become very popular. However many other Peer-to-Peer WLAN modes have been developed and are gaining prominence. one such protocol is termed Wi-Fi Direct (p2p — Peer to Peer) which is actively being used in smartphones for gaming/payments etc.

Variations of a Peer to Peer network within the scope of an infrastructure setup have also been developed – termed Tunneled Direct Link Setup (TDLS). 

In addition to to the above Wireless Mesh network standards have also been developed which employs a number of inter-connected nodes in mesh formation. 

WLAN is also finding its use in automotive communication in recent years.

Introduction to Wireless LAN (Contd)

Leave a Reply

Your email address will not be published. Required fields are marked *