Introduction, basics and standards for Wi-Fi Networks

This article covers a short introduction to Wi-Fi Networks, why they are exciting, what are the basic components involved in building a Wi-Fi Network, what are the standards used in Wi-Fi Networks and an overview of the competition.

What makes Wi-Fi Networks Exciting (Advantages of a Wireless Network)?

¤ Sheer convenience of being able to connect to the network anywhere instead of designated points only.
¤ Mobility – An employee can connect to the same network whether from his work space, canteen or the conference room.
¤ The cost of setting up a wired network and maintaining it is far cheaper than a wired network.
¤ Today’s wireless networks can give advanced services like User Access Control, Wireless Intrusion prevention etc. on par with wired networks.
¤ Availability of many network devices (Like PC’s, laptops, mobiles, IP Cameras, LCD Projectors etc.) that can connect to the wireless network on common standards.

Introduction/Basics of a Wireless Network:

Basically, wireless networks (Wi-Fi) are the radio signals generated between communicating devices on a common frequency (2.4Ghz or 5 Ghz). An Access Point/Router generates the wireless signals and propagates it in an omni directional wave pattern which are picked up by the wireless adaptors in clients (PC’s, Mobile devices etc) and vice versa so that the data can flow between them over the air (Even in Non-Line of Sight – NLOS conditions) with a certain rate of connectivity called bandwidth (Usually defined in Kilo bytes per second or Mega bytes per second). Normally several PC’s can connect to one Access Point/ Router and the bandwidth decreases with increasing devices connecting to same AP’s as well as increasing distances between an AP and Wireless adaptors on clients. Wireless networks today are not only an alternate network/backup to wired networks but they are the primary access network in many places.

Components of a Wireless Network:

A wireless network consists of a Access Point/Wireless Router/Wireless Controller at the centre and the Clients/PC’s (with wireless adaptors) to connect to the Access Points over the wireless network. It also consist of a back end wired network (Which connects the various Access Points, Wireless Controller and the data centre/Internet/servers etc). The Access Points can connect to themselves (back end connectivity) using another wireless radio and this is called a Mesh Network. All the devices need to be compliant with the IEEE Wi-Fi Standards to interoperate with each other.

IEEE Standards for Wi-Fi Networks:

As you have noticed above, there are quite a few components required for setting up a wireless network. But often, these components are manufactured by different vendors. In order to understand each other, they follow certain rules while transmitting and receiving information. These rules are called protocols and they are set by a common body called IEEE. So, devices wanting to connect to wireless networks must adhere to any one of the following standards:

IEEE 802.11a: This standard transmits at 5 Ghz frequency and gives up to 54 Mbps of shared bandwidth. The range (distance covered) by this protocol is slightly less than the more popular IEEE802.11g but it is a clean frequency with minimum disturbance/interference.

IEEE 802.11b: This standard transmits at 2.4 Ghz frequency and gives up to 11 Mbps of shared bandwidth. The devices built using this radio are cheaper and hence it was popular until the next standard came by.

IEEE 802.11g: This is the currently popular protocol that operates in the 2.4 Ghz frequency band and gives upto 54 Mbps of bandwidth. The range of coverage is almost twice that of 802.11a and since almost all laptops come with a default b/g adaptor, there are no compatibility issues. But 2.4 Ghz is a highly crowded spectrum, and there maybe some disturbances.

IEEE 802.11n: This is the newest standard (yet to be completely ratified by IEEE). It uses multiple radios to give a higher throughput (MIMO – Multiple In and Multiple Out technology). Currently it gives a bandwidth of 300 Mbps (Practically achievable is half of that) and once ratified, it is expected to give upto 600 Mbps. Since the hardware compatibility is already defined, the laptops and Access points are available with 802.11n radios built into it.

These standards are backward compatible. For example, the radios which work in 802.11n can also work in 802.11b or g protocols to ensure investment protection for legacy devices.

Update: Everything you wanted to know about Wireless (Wi-Fi) Network

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