What is wireless network explain in details | Computer Networks

Need for Wireless LAN

There are many reasons :

• An increasing number of LAN users are becoming mobile.
• These mobile users require that they be connected to the network regardless of where they are because they want simultaneous access to the network.
• This makes the use of cables, or wired LANs, impractical if not impossible.
• Wireless LANs are very easy to install.
• There is no requirement for wiring every workstation and every room.
• This ease of installation makes wireless LANs inherently flexible.
• If a workstation must be moved, it can be done easily and without additional wiring, cable drops, or reconfiguration of the network.
  
• Another advantage is its portability. If a company moves to a new location, the wireless system is much easier to move than ripping up all of the cables that a wired system would have snaked throughout the building.
• Most of these advantages also translate into monetary savings.
• Ad Hoc networks (discussed later) are easily set up in a wireless environment.

How Wireless LAN Work?

• Wireless LAN (WLAN) uses electromagnetic airwaves (radio and infrared) to communicate information from one point to another without relying on any physical connection.
• Radio waves are often referred to as radio carriers because they simply perform the function of delivering energy to a remote receiver.
• The radio data carrier being transmitted can be accurately superimposed and extracted at the receiving end.
• This is generally referred to as modulation of the carrier by the information being transmitted.
• Once data is superimposed (modulated) onto the radio carrier, the radio signal occupies more than a single frequency, since the frequency or bit rate of the modulating information adds to the carrier.
• Multiple radio carriers can exist in the same space at the same time without interfering with each other if the radio waves are transmitted on different radio frequencies.
• In a typical WLAN configuration, a transmitter/receiver (transceiver) device, called an access point (AP), connects to the wired network from a fixed location using a standard Ethernet cable.
• At a minimum, the access point receives, buffers, and transmits data between the WLAN and the wired network infrastructure.
• A single access point can support a small group of users and can function within a range of less than one hundred to several hundred feet.
• The access point (or the antenna attached to the access point) is usually mounted high but may be mounted essentially anywhere that is practical as long as the desired radio coverage is obtained.
• End users access the WLAN through wireless LAN adapters, which are implemented as USB adapters, PC cards in notebook computers, ISA or PCI cards in desktop computers, or fully integrated devices within handheld computers. WLAN adapters provide an interface between the client network operating system (NOS) and the airwaves (via an antenna).
• The nature of the wireless connection is transparent to the network operating system.

Advantages of Wireless LANs :

Wireless networks offer the following productivity, service, convenience, and cost advantages over traditional wired networks :

Mobility Improves Productivity and Service: Wireless LAN systems can provide LAN users with access to real-time information anywhere in their organization. This mobility supports productivity and service opportunities not possible with wired networks

Installation Speed and Simplicity: Installing a wireless LAN system can be fast and easy and can eliminate the need to pull cable through walls and ceilings.

Installation Flexibility: Wireless technology allows the network to go where the wire cannot go.

Reduced Cost-of-Ownership: While the initial investment required for wireless LAN hardware can be higher than the cost of wired LAN hardware, overall installation expenses and life-cycle costs can be significantly lower. Long-term cost benefits are greatest in dynamic environments requiring frequent moves, adds, and changes.

Scalability: Wireless LAN systems can be configured in a variety of topologies to meet the needs of specific applications and installations. Configurations are easily changed and range from independent networks suitable for a small number of users to full infrastructure networks of thousands of users that allow roaming over a broad area.

Applications of Wireless LANs :

1. LAN extensions  2.Ad-hoc networks  3.Nomadic access