WLAN Concepts
A WLAN (Wireless Local Area Network) is a type of wireless network that is used almost everywhere (ex. homes, offices, factories, cafes, etc…). Just imagine today’s world full of laptops, tablets, smart-phones, and other devices without wireless transmission. WLAN is that one thing that makes mobility possible within domestic and business environments.
Types of Wireless Networks
Wireless networks are based on the standards published by the Institute of Electrical and Electronics Engineers (IEEE) and are mainly classified into four main types:
| WPAN (Wireless Personal Area Networks) |
| Uses low powered transmitters for short-range network coverage, usually 20-30 feet (6 to 9 meters). Examples of such a network are Bluetooth, ZigBee, and WiMAX. WPANs are based on the 802.15 standards using a 2.4GHz radio frequency. |
| WLAN (Wireless Local Area Networks) |
| Uses larger transmitters to cover medium-sized networks, usually up to 300 feet (92 meters). WLANs are used in home, office, SOHO, and/or campus environments. WLANs are based on the 802.11 standards and can use both 2.4GHz or 5GHz radio frequencies. |
| WMAN (Wireless Metropolitan Area Networks) |
| Uses large transmitters to provide wireless service over a large geographic area. WMANs are used to provide wireless service to a metropolitan city and/or district. WMANs use specific licensed frequencies. |
| WWAN (Wireless Wide rea Networks) |
| Uses large transmitters to provide wireless service over an extensive geographical area. WWANs are used for national and global communications and also use specific licensed frequencies. |
Types of Wireless Technologies
Wireless technologies use an unlicensed radio spectrum to send and receive data. Such a spectrum is available to anyone who has wireless in the device being used.
| Bluetooth |
| Uses the IEEE 802.15 WPAN standard that operates on a device-pairing basis to communicate over distances up to 300 feet (100 meters). Such technology is usually found in smart-home devices, audio-devices, vehicles, and many other devices that require a short distance connection. 2 types of Bluetooth Radios exist: BLE (Bluetooth Low Energy) – Supports multiple network technologies from mesh topology to large scale network devices. BR/EDR (Bluetooth Basic Rate/Enhanced Rate) – Supports point to point topologies and is optimized for audio streaming. |
| WiMAX (Worldwide Interoperability for Microwave Access) |
| This is an alternative to broadband wired internet connections. WiMAX is typically used in locations that are not connected to a DSL or cable provider. It uses the IEEE 802.16 WWAN standard that provides high-speed wireless broadband access of up to 30 miles (50 kilometers). The way WiMAX operates is very similar to WiFI, but at much higher speeds and larger distances, also supporting larger numbers of users. WiMAX makes use of antennas hooked up to network towers similar to cell phone towers. At times, WiMAX transmitters and cellular transmitters may even share space on the same tower. |
| Cellular Broadband |
| Cellular Broadband networks (ex.4G/5G) are wireless mobile networks mainly used by cellular phones but can also be used in vehicles, tablets, laptops, and other devices. Such networks are multi-access networks, meaning that they are able to carry both data and voice communications. A cell site is created by a cellular tower transmitting signals in a given area. Interconnecting cell sites form the cellular network. The two main types of cellular networks which are GSM (Global System for Mobile) and CDMA (Code Division Multiple Access). GSM is globally recognized and CDMA is mainly used in the US. 4G (4th Generation GSM Network) is the presently most used mobile network. It delivers speeds that are 10x faster than its predecessor 3G, whilst the new 5G is promised to deliver 100x faster speeds than 4G and also withstands more user capacity. |
| Satellite Broadband |
| This type of technology provides network access to remote sites via directional satellite dishes that are aligned with a specific geostationary Earth orbit satellite. This is an expensive technology and it requires a clear line of sight. Such technology is used where Cable and DSL are not available (ex. rural homeowners and businesses). |
802.11 Wireless Standards
Most of the standards portray that wireless devices have one antenna to transmit and receive wireless signals on the specified radio frequency (2.4 GHz or 5 GHz), thus some of the newer standards that are able to transmit and receive at much higher speeds require access points (APs) and wireless clients to have multiple antennas using the MIMO (Multiple Input / Multiple Output) technology.
MIMO technology uses multiple antennas acting as both a transmitter and a receiver to improve communication performance. A maximum of 4 antennas is supported
The following is a list of standards implemented by IEEE over the years
| Standard | Frequency | Detail |
|---|---|---|
| 802.11 | 2.4GHz | – Up to 2Mbps speeds |
| 802.11a | 5GHz | – Up to 54Mbps speeds – small area coverage – less effective at penetrating buildings – not interoperable with 802.11b and 802.11g |
| 802.11b | 2.4GHz | – Up to 11Mbps speeds – longer range than 802.11a – better ability to penetrate buildings |
| 802.11g | 2.4GHz | – Up to 54Mbps speeds – Backward compatible with 802.11b with reduced bandwidth capacity |
| 802.11n | 2.4GHz 5GHz | – 150Mbps to 600Mbps with a distance range of up to 230 feet (70 meters) – Access Points and wireless clients require multiple antennas via MIMO technology – backward compatible with 802.11a/b/g devices with limiting data rates |
| 802.11ac | 5GHz | – 450Mbps to 1.3Gbps via MIMO technology – Up to 8 antennas supported – Backward compatible with 802.11a/n devices with limiting data rates |
| 802.11ax | 2.4GHz 5GHz | – Latest standard launched in 2019 – aka. HEW (High-Efficiency Wireless) – Higher data rates – Increased capacity – Handles a lot of connected devices – Improved power efficiency – 1 GHz and 7 GHz capable |
Radio Frequencies
All wireless devices operate in the “Radio Waves” range within the electromagnetic spectrum being 2.4GHz and 5GHz frequencies.
The following frequency bands are allocated to 802.11 Wireless LANs
- 2.4 GHz Ultra-High Frequency (UHF)
- 802.11b/g/n/ax
- 5 GHz Super-High Frequency (SHF)
- 802.11a/n/ac/ax
Wireless Standards Organisations
Standards exist to ensure interoperability between devices that are manufactured by different brands.
The 3 organisations managing WLAN standards are the following
| ITU – International Telecommunication Union |
| Regulates the allocation of the radio frequency spectrum and satellite orbits through the ITU radio-communication sector. |
| IEEE – Institute of Electrical and Electronics Engineers |
| Specifies how a radio frequency is modulated to carry information. |
| Wi-Fi Alliance |
| A global, non-profit, industry trade association devoted to promoting the growth and acceptance of WLANs. |