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Official (old) logo for WiFi, created by the Wi-Fi Alliance

WiFi is a form of wireless internet access (Wireless Local Area Network) which complies with the IEEE's 802.11 standards. The protocols and standards used by WiFi are governed by the Wifi Alliance, which is composed of an international network of companies.[1] It was originally invented by the Australian government's research arm, the CSIRO. WiFi networks use a star architecture to service numerous devices within proximity of the access point (or "hotspot"). Wireless access points can be teamed together to offer seamless service over a relatively large area, be switching off clients from one access point to another as is needed to maintain connectivity. This is typically done by companies with a large amount of square footage to service, such as hotels, hospitals, restaurants, airports, schools and universities, and shopping malls.
Access points are typically connected to some form of high-speed internet service, such as DSL/cable or fiber optic lines. These access points generally transmit their identification (called an SSID) so users can easily connect to them using any WiFi-capable device, such as a laptop, smartphone, tablet, or portable gaming device.

Since information is being broadcast (so that anyone within range can "hear"), the signal is often encrypted, using protocols such as WEP, WPA, or WPA2. Unfortunately, all three of these are vulnerable to attackers and do not therefore provide the security they were intended too. The Wifi Alliance announced in 2018 that it was working on creating WPA3, which they promise will offer more robust security than the previous failed attempts.[2][3]

In some places such as Sunnyvale in Silicon Valley, WiFi is largely replaced by WiMAX, which can service entire cities.

Common WiFi Standards

The average user's experience tends to be that any WiFi-capable device they have can connect to any WiFi network for which they know the password (if there is one). However, there is a set of standards which define how, from a technical perspective, the devices work. Unfortunately, not all devices are compatible with all others. The following are some of the 802.11 standards, at least one of which will need to be supported by both ends in order for communication to be established.
Network adapters are often listed with the standards they support in a list, such as "802.11a/b/g/n." For this example, the adapter would support networks using 802.11a, 802.11b, 802.11g, and 802.11n. This multi-compatibility is what enables most users to connect to most networks, even though not all are the same.

Standard Best possible speed Frequency About
802.11ah (Wi-Fi HaLow) 347 Mbps About 900 MHz Utilizes an extremely low-frequency to extend its range. This is used for license-exempt networks, and consumes less power than typical wireless networks.[4] This is intended to better support IoT and other "smart" devices due to the low power requirements.[5]
802.11ad (802.11aj) 6.7Gbps 60 GHz Sacrifices range in favor of speed. This protocol uses a a relatively high radio frequency to increase throughput, but the high frequency signal rapidly decays, so clients must be in close proximity of the access point to use this.[4] In China, this standard has been essentially copied and rebranded as 802.11aj or "China Millimeter Wave."[6]
802.11ac (Wi-Fi 5) 3.46 Gbps 5 GHz Typically used by home WiFi networks, this protocol offers somewhat of a balance between speed and range. This protocol offers Multiple Input, Multiple Output (MIMO) support, allowing for multiple antennas to send/receive in order to improve performance. This protocol is widely accepted, although some older devices may not support it. Fortunately, this protocol supports dual-band operation (and is the first to do so). This means that many access points using 802.11ac also offer 2.4GHz service using 802.11n to serve older devices.[4][6] This support of 802.11n enables 802.11ac to be backward compatible with the common b/g/n equipment.[7]
802.11n (Wi-Fi 4) 300 Mbps 2.4 GHz or 5 GHz Intended to improve on 802.11g by using multiple antennas (MIMO). This offers backward-compatibility with 802.11b/g equipment. This standard offers a significant bandwidth improvement, but can be more costly to implement. Additionally, the use of multiple signals may interfere with nearby 802.11b/g based networks.[6]
802.11g 54 Mbps 2.4 GHz Approved in 2003, this standard enables communication at the same speed as 802.11a, but uses a lower radio frequency which increases the range.[4]
802.11a 54 Mbps 5 GHz Released after 802.11b (yes, that's right--"b" came before "a"), this standard offered a speed improvement (at the cost of range) over 802.11b by switching to a higher frequency.[4]
802.11b 11 Mbps 2.4 GHz Released before 802.11a, this protocol was widely used in early access points.[4]
802.11-1997 2 Mbps 2.4 GHz Early standard which offered what is now a very low speed at a very short range (66 feet of indoors, 330 feet outdoors).[4]

See also