WLAN tutorial discusses the basic concept about wireless Local area networking including the wireless topology and the wireless standards.
In this WLAN tutorial, you need to know what the concept of the Wireless networking is. It’s a set of technologies used to replace traditional wired Ethernet local area network (LAN) with wireless networking. The popularity of the WLAN technologies is increasing in networking environments including home usages and large companies.
Wireless Networking Background
Before we go further in this WLAN tutorial, firstly we need to discuss the wireless networking itself. Wireless networking uses electromagnetic waves which travel through free space to connect stations on a network. In the broadest sense, wireless networking is composed of all forms of network communication that use electromagnetic waves of any wavelength or frequency, which includes the following portions of the electromagnetic spectrum:
- 1. Infrared (IR) laser:
Generally we call it optical wireless which is a point-to-point wireless communication with the frequency ranges from about 300 gigahertz (GHz) to 200 terahertz (THz) and is used primarily in confined areas where line-of-sight communication is possible. Unfortunately IR cannot penetrate material (building or structure) but it can reflect off light-colored surfaces. Besides, IR is absorbed by water vapor, so fog or rain can disrupt network communications. We will not discuss any further in this WLAN tutorial.
- 2. Microwave
Another type of wireless point-to-point communication is Microwave which the frequency ranging from 2 GHz to 40 GHz. This wireless technology is widely used for both terrestrial and satellite communication. Microwave also suffers from signal degradation when weather conditions are poor, but not as much as IR.
- 3. Broadcast radio
Another wireless networking type is the radio broadcast which uses the frequency ranges from 30 MHz to 1 GHz. Unlike IR and Microwave, this broadcast radio can be used in both point-to-point and multipoint topologies and can travel through most buildings and structures, but it suffers from multipath interference when traveling over long distances. We do not discuss microwave and radio broadcast too far in this WLAN tutorial.
Wireless local area network (WLAN)
WLAN technologies are used to replace or enhance traditional wired Ethernet local area networks (LANs) and are extremely popular in the enterprise. The most popular WLAN technology used to be 802.11b, which operates in the unlicensed 2.4 GHz band and provides speeds up to 11 megabits per second (Mbps). But today, with the introduction of the draft 802.11n wireless standards (which was approved last Sep 2009 as the final 802.11n), the popularity of the legacy wireless standards 802.11b and 802.11g is beginning to be replaced with the final version of 802.11n standards. Many manufacturers ship their wireless routers with this final 802.11n standard such as Linksys E-Series and new Belkin wireless routers.
WLAN Topologies
The WLAN tutorial should also cover the concept of wireless topology. The term topology in computer networking typically refers to the pattern of the cables used to connect the computers. Unlike wired networks, wireless networks do not use cables. The wireless topology defines how the wireless devices interact at the physical layer of the OSI model where WLAN uses direct sequence spread spectrum communications at a frequency of 2.4 GHz (or 5 GHz in 802.11a standards), and the devices can communicate with each other using two basic topologies: ad hoc and infrastructure.
Ad Hoc Wireless Topology
If two or more wireless devices communicate directly with each other, it is a wireless Ad-Hoc topology.
Typically the WLAN adapters generate the Omni-directional signal patterns out to a range that is governed by environmental factors, as well as the nature of the equipment involved which the range is called a basic service area (BSA). Two wireless devices will be able to communicate with each other when they come within the wireless range and immediately forming a two-node network. Wireless devices within the same basic service area are called a basic service set (BSS).
Other wireless devices can also participate with the first two when they are coming within the transmission range. However, Ad-hoc networking is not transitive. A wireless device that comes within range of another device, but still lies outside the range of a third, can only communicate with the device in its range.
Ad-Hoc wireless networking has the following benefits:
- Setting up the network is simple, just plug in the wireless adapters, configure the included software, and go.
- You don’t need to purchase the wireless access point, save you money.
- Ad-hoc networks are faster, twice the throughput rates between two wireless network adapters are twice compared to wireless infrastructure.
There are many wireless devices which have the Ad-hoc feature as well as infrastructure feature mode such as the Bluetooth wireless print server.
Infrastructure Network
In infrastructure wireless networks, you need a wireless access point that functions as the bridge between computers in the wireless network and the computers in the wired networks. The access point functions as a transparent bridge which effectively extends the wired LAN to include the wireless devices. Wireless devices do not communicate with each other directly, but through the access point.
Mostly the WLAN networks uses the wireless access point and all the wireless routers include the function of the access point built-into the router.
Wireless infrastructure networks have the following benefits:
- With wireless access point, you can easily expand your existing wired networks wirelessly to allow wireless devices in the wireless networks communicate with the network devices on the wired networks.
- Many wireless access points have the WDS (Wireless distribution system) capability features to allow users roaming between the Access Points in large network environments.
- To allow you share the internet connection with many computers in home.
Mostly wireless LANs (WLANs) use the concept of this wireless infrastructure.
How to Build a WLAN
In this WLAN tutorial you can also learn how to build a simple WLAN network. The most obvious reason you build a wireless network in home is to share the broadband internet connection and other sharing purposes. What you need is Cable or ADSL services from your ISP, the modem (typically supplied by the ISP), and the wireless router or the wireless access point.
There are many all-in-one devices you can use to build a wireless network, one single device with router and modem functions such as xDSL router modem or Cable router modem. For complete article how to build a wireless network click the link.
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