What is Wi-Fi?
Wi-Fi refers to a wireless networking technology that uses radio waves to create a Wireless Local Area Network (WLAN). The name of Wi-Fi doesn’t stand for anything, but just a logo and trademark chosen by Wireless Ethernet Compatibility Alliance (now Wi-Fi Alliance, renamed itself in 2002).
Wi-Fi generations/IEEE standards
Wi-Fi indeed bases on IEEE 802.11, but it is not totally equal to that standard, because not all sub standards under IEEE 802.11 are using by Wi-Fi. For example, IEEE 802.11c is an amendment to IEEE 802.1D MAC bridging standard.
In 2018, Wi-Fi Alliance changed the naming rule to make it easier to understand and recognize. Now Wi-Fi Alliance does not call Wi-Fi standards as IEEE 802.11b, a, g, n, x anymore, but simply names them like Wi-Fi 1,2,3…n, and changes their certification trademark also.
|Name||Protocol||Year||Frequency||Actual speed||Theoretical speed||Indoor range||Outdoor range|
|Wi-Fi 1||802.11b||1999||2.4-2.5 GHz||6.5 Mbit/s||11 Mbit/s||about 30 meters||about 100 meters|
|Wi-Fi 2||802.11a||1999||5.15-5.35/5.47-5.725/5.725-5.875 GHz||25 Mbit/s||54 Mbit/s||about 30 meters||about 45 meters|
|Wi-Fi 3||802.11g||2003||2.4-2.5 GHz||25 Mbit/s||54 Mbit/s||about 30 meters||about 100 meters|
|Wi-Fi 4||802.11n||2009||2.4 GHz or 5 GHz bands||300 Mbit/s（20MHz*4 MIMO）||600 Mbit/s（40MHz*4 MIMO）||about 70 meters||about 250 meters|
|Wi-Fi 5||802.11ac||2011.11||5 GHz||433Mbit/s, 867Mbit/s（Optional 80MHz，160MHz）||867Mbit/s, 1.73 Gbit/s, 3.47 Gbit/s, 6.93 Gbit/s（8 MIMO，160MHz）||about 35 meters|
|Wi-Fi 6||802.11ax||2018.12||2.4/5 GHz||10.53Gbps||10 meters||100 meters|
Note: Wi-Fi 1 to 3 also called Legacy Wi-Fi since they are not widely in use now.
2.4GHz and 5GHz Frequency
2.4 GHz and 5 GHz are most common radio frequencies used for Wi-Fi today. Although you use them every day even for now, you may not completely know the difference between them: 2.4 GHz has long transmission range and strong through-wall penetration, but low transfer speed and more signal interference (micro-wave), while 5 GHz has high transfer speed, but short transmission range and weak penetration.
The wireless channel is a specific division of frequencies in a specific wireless band.
On 2.4 GHz
There are totally fourteen channels defined for the 2.4 GHz ISM band in IEEE 802.11, but not all these Wi-Fi channels are available in all countries. In USA, there are 11 channels allowed by the FCC, and 13 are allowed in Europe where channels have been defined by ETSI. The WLAN / Wi-Fi channels are spaced 5 MHz apart (except for a 12 MHz spacing between the last two channels).
|Channel||Center Frequency||USA||Canada||Most Countries|
With the use of IEEE 802.11n, it is possible to use signal bandwidths of either 20 MHz or 40 MHz. 2.4 Ghz Transmission can be on a 22MHz (802.11b), 20MHz (802.11g/n), or 40MHz (802.11n) wide channel. When 40 MHz bandwidth is used to gain more than twice data transfer speed than 20MHz bandwidth, this obviously speeds up the data throughput, but reduces the number of channels that can be used.
|Channel||Or Channel||Center Frequency||USA||Canada||Most Countries|
On 5 GHz
Transmission can be achieved on a 20 or 40MHz (802.11a/n), 80 or 160MHz (802.11ac) wide channel
|Channel Width||Valid Channel Numbers|
|20 MHz||36, 40, 44, 48, 52, 56, 60, 64, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144, 149, 153, 161, 165, 169|
|40 MHz||38, 46, 54, 62, 102, 110, 118, 126, 134, 142, 151, 159|
|80 MHz||42, 58, 106, 122, 138, 155|
|160 MHz||50, 114|
- U-NII: Unlicensed National Information Infrastructure
- TDWR = Terminal Doppler Weather Radar
Note: Devices must be professionally installed when operating in the U-NII-2C (5470 – 5725 MHz band)
|Channel||Lowest Frequency (MHz)||Center Frequency (MHz)||Highest Frequency (MHz)||Available in North America|
To improve wireless security, you have many options, such as setting a secure password, or creating a MAC whitelist to allow known device access to the Wi-Fi network, or creating a guest Wi-Fi that allows other people to access the Internet other than your home network.
Another important thing is encryption method. Choosing the proper level of encryption is just as vital, and the choice will determine whether your wireless LAN is a house of straw or a shielded fortress. Most wireless access points (APs) come with the ability to enable one of three wireless encryption standards: Wi-Fi Protected Access (WPA), WPA2 or WPA3.The corresponding security level strength: WPA< WPA2 < WPA3.
High-data transfer speed
Compared to other wireless technologies like Bluetooth, Wi-Fi has absolute advantage in data transfer. Generally, Wi-Fi 6 has a base speed of 1.2 Gbps (1,200 Mbps) per stream. Hence, a dual-stream connection has a ceiling speed of 2.4 Gbps, and a quad-stream one tops at a whopping 4.8 Gbps. However, for Bluetooth 5.0, devices can only use data transfer speeds up to 2 Mbps.
MIMO and MU-MIMO
MIMO is short for Multiple-Input Multiple-Output, which is a wireless technology that uses multiple transmitters and receivers to transfer more data at the same time. Wi-Fi CERTIFIED devices send and receive more than one communication signal simultaneously through multiple antennas. This multiplies the performance of the Wi-Fi signal, and is reflected in the two, three, or even more antennas found on some Wi-Fi CERTIFIED n AP (access point) devices or routers. All wireless products with Wi-Fi 4(802.11n) protocol support MIMO. The technology helps Wi-Fi 4 to achieve higher speeds than products without it.
MU-MIMO is short for Multi-user, multiple-input, multiple-output technology simultaneously. As a part of the Wi-Fi 5 (802.11ac) standard, MU-MIMO allows an AP or Router to communicate with multiple devices, increasing the speed of the data transfer without congestion.
Beamforming is a process that allows you to focus your Wi-Fi signal. … Wi-Fi beamforming narrows the focus of router signal, sending it directly to your devices in a straight line, thus minimizing surrounding signal interference and increasing the strength of the signal for each device.
Mesh Wi-Fi Network consists of a main router that connects directly to your modem, and a series of satellite modules, or nodes, placed around your house for full Wi-Fi coverage. As part of a single wireless network, these modules share the same SSID and password, unlike traditional Wi-Fi routers.
Common Device types
A standard modem is a small box that connects your devices (computers, set-top boxes, etc.) to the Internet using cables. In order to enable a wireless (Wi-Fi) connection in your home, your modem must be paired with a separate device called a router.
A wireless router connects directly to a modem by a cable. This allows it to receive information from — and transmit information to — the Internet. The router then creates and communicates with your home Wi-Fi network using built-in antennas. As a result, all of the devices on your home network have internet access.
Wi-Fi boosters, repeaters, and extenders are mostly the same thing – devices to improve Wi-Fi coverage. There isn’t a clearly defined difference between devices described as “repeaters” by manufacturers and devices described as “extenders”. However, not all Wi-Fi extenders work in exactly the same way.
Although not all Wi-Fi devices in market are Wi-Fi certified products, those devices with Wi-Fi CERTIFIED seal must pass Wi-Fi Alliance certification program. You can also look for the qualified product here: https://www.wi-fi.org/product-finder
Ethernet is the most pervasive connection type for wired networking, available in speeds from 10mbps all the way up to 10,000mbps (10gbit). The most common wire used for Ethernet networking is Cat5 (Category 5) and the connectors used are RJ45, slightly larger than the RJ11 connectors used by phones, but the same shape.
Access Point (AP)
An access point is a device that creates a wireless local area network (WLAN), usually in an office or large building. An access point connects to a wired router, switch, or hub via an Ethernet cable, and projects a Wi-Fi signal to a designated area. For example, if you want to enable Wi-Fi access in your company’s reception area but don’t have a router within range, you can install an access point near the front desk and run an Ethernet cable through the ceiling back to the server room.
A hotspot is an access point set up specifically to provide Internet access for users. There are also mobile hotspots — you can share your cellular data from a smart phone, just as if they were a wireless router that others can connect to surf the Internet.
Power Line Communication (PLC)
Power Line Communication is a communication technology that enables sending data over existing power cables. This means that, with just power cables running to an electronic device (for example), one can both power it up, while controlling/retrieving data from it in a half-duplex manner.