What is WLAN

With the advent of mobile phones, cameras, and Personal Digital Assistants (PDAs), the WLAN technology is becoming very popular.

Wireless Local Area Network or WLAN is sometimes referred as LAWN, for local area wireless networks. WLAN establishes a wireless radio connection between a mobile user and another computing device via LAN network. It links two or more wireless devices through a wireless distribution method within a local coverage area such as a school, home, computer laboratory, and office. It allows any user to move around in a small area, while still being connected to the network. Most of the modern WLANs are based on IEEE 802.11 standards and are marketed under the WiFi brand name.

Technical Standard in WLAN

Technical standards are the major concerns for a user looking to buy wireless LAN products. IEEE has set up a universal standard for wireless LANs. According to the project IEEE 802.11, 1Mbps is the minimum required bandwidth for WLANs to operate or transmit the digital data including voice, and audio files.

Types of WLANs:

Ad-hoc Networks: This type of network can be set up based on the number of users meeting in a small room or a conference, without requiring any wireless support or access point.

Ad-hoc networks are a key factor in the evolution of wireless communications. Ad-hoc networks are used in real-time business applications, corporate companies to increase the productivity and profit. Ad-hoc networks of PDAs or laptops are used in disaster relief, conferences and battlefield environments.

Infrastructure networks: In this type of network, the devices that are connected through a single access point or a wireless router. For example: Two persons sitting next to each other with two different laptops and communicating indirectly through the same wireless access point.

Different Transmission Methodologies Used in WLANs

There are three major methods used by WLANs to transmit information:

Microwave transmission: It is the technology which uses radio waves to transmit information or energy. For example: ALTAIR, a Motorola’s WLAN product transmits data by using low power microwave signals at the frequency of 18 GHz.

Spread Spectrum Transmission:

In this technology, there are two methods used by wireless LAN products which are:

• Frequency Hopping: The transmitter device detects an ideal time and transmits the data using full channel bandwidth. If the channel is full, it hops the data to another channel and repeats the process.
• Direct Sequence Modulation: In this method, the transmitter operates in a wide frequency range using Code Division Multiple Access (CDMA), which generates a code–through which a receiver identifies the signal transmitted by the sender unit. The frequency at which these signals are transmitted is called ISM (Industrial Scientific and Medical) band.

Infrared Transmission:

This method uses infrared light to transmit data. There are three types of infrared transmission methods.

• Diffused: The sender unit fills the entire area with infrared light so that the receiver located in that area can receive the signals.
• Directed: In this methodology, the infrared light is focused before transmitting the signal, which increases the rate of transmission.
• Directed point-to-point: It provides the highest transmission speed than the other methodologies. Because in this method, the sender unit is aligned with the receiver unit and then the infrared light is focused directly to the receiver.