What is WiFi?

Wi-Fi is a wireless networking technology that uses radio waves to create Wireless Local Area Network (WLAN), the name of Wi-Fi doesn’t stand for anything, it just a logo and trademark chosen by Wireless Ethernet Compatibility Alliance (now Wi-Fi Alliance, renamed itself in 2002).

Factors of Wi-Fi

WiFi generations/IEEE standards

Wi-Fi indeed base on IEEE 802.11, but Wi-Fi 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 the IEEE 802.1D MAC bridging standard.

In 2018, Wi-Fi Alliance change the naming rule for easier to understand and recognize, now Wi-Fi Alliance not call Wi-Fi standards for IEEE 802.11b, a, g, n, x anymore, but simply naming like Wi-Fi 1,2,3…n, and change 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 today.

Differences between 2.4GHz and 5GHz

2.4 GHz and 5 GHz are most common radio frequencies used for Wi-Fi today, although you use them everyday even for now, but you may not complete know the differences between them, hit to the point, 2.4 GHz has long range and strong penetrability for wall, but low transfer speed and more signal interference(micro-wave), on the other hand,5 GHz has high transfer speed, but less short range and weak penetrability.

Frequency channel

2.4 GHz

IEEE 802.11 have total fourteen channels defined for the 2.4 GHz ISM band, but not all of 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 (with the exception of a 12 MHz spacing between the last two channels).

Channel

Center Frequency

USA

Canada

Most Countries

1

2412

Y

Y

Y

2

2417

Y

Y

Y

3

2422

Y

Y

Y

4

2427

Y

Y

Y

5

2432

Y

Y

Y

6

2437

Y

Y

Y

7

2442

Y

Y

Y

8

2447

Y

Y

Y

9

2452

Y

Y

Y

10

2457

Y

Y

Y

11

2462

Y

Y

Y

12

2467

N

N

Y

13

2472

N

N

Y

14

2484

N

N

N

With the use of IEEE 802.11n, there is the possibility of using 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 compares to 20MHz bandwidth, this obviously speed up the data throughput, but reduces the number of channels that can be used.

Channel

Or Channel

Center Frequency

USA

Canada

Most Countries

3

1+5

2422

Y

Y

Y

11

9+13

2462

N

N

Y

5 GHz

Transmission can be on a 20 or 40MHz (802.11a/n), 80 or 160MHz (802.11ac) wide channel

  • 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

Frequency (MHz)

 

Lowest

Center

Highest

Available in North America

36

5170

5180

5190

Y

40

5190

5200

5210

Y

44

5210

5220

5230

Y

48

5230

5240

5250

Y

52

5250

5260

5270

DFS

56

5270

5280

5290

DFS

60

5290

5300

5310

DFS

64

5310

5320

5330

DFS

100

5490

5500

5510

DFS

104

5510

5520

5530

DFS

108

5530

5540

5550

DFS

112

5550

5560

5570

DFS

116

5570

5580

5590

DFS

120

5590

5600

5610

DFS

124

5610

5620

5630

DFS

128

5630

5640

5650

DFS

132

5650

5660

5670

DFS

136

5670

5680

5690

DFS

140

5690

5700

5710

DFS

144

5710

5720

5730

DFS

149

5735

5745

5755

Y

153

5755

5765

5775

Y

157

5775

5785

5795

Y

161

5795

5805

5815

Y

165

5815

5825

5835

Y

DFS – Dynamic Frequency Selection is a WiFi function that enables WLANs to use 5 GHz frequencies that are generally reserved for radars

MIMO and MU-MIMO

MIMO is a 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 make use of multiple antennas to send and receive more than one communication signal simultaneously. 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 allow Wi-Fi 4 to reach higher speeds than products without it.

MU-MIMO is short for Multi-user, multiple-input, multiple-output technology simultaneously, it is 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.

WiFi Beamforming

Beamforming is a process that allows you to focus your WiFi signal. … WiFi beamforming narrows the focus of that router signal, sending it directly to your devices in a straight line, thus minimizing surrounding signal interference and increasing the strength of the signal that each device. Beamforming is a process that allows you to focus your WiFi signal. … WiFi beamforming narrows the focus of that router signal, sending it directly to your devices in a straight line, thus minimizing surrounding signal interference and increasing the strength of the signal that each device.

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