Wifi Definition and 68 Threads

Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks in the world, used globally in home and small office networks to link desktop and laptop computers, tablet computers, smartphones, smart TVs, printers, and smart speakers together and to a wireless router to connect them to the Internet, and in wireless access points in public places like coffee shops, hotels, libraries and airports to provide the public Internet access for mobile devices.
Wi‑Fi is a trademark of the non-profit Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing. As of 2017, the Wi-Fi Alliance consisted of more than 800 companies from around the world. As of 2019, over 3.05 billion Wi-Fi enabled devices are shipped globally each year.Wi-Fi uses multiple parts of the IEEE 802 protocol family and is designed to interwork seamlessly with its wired sibling Ethernet. Compatible devices can network through wireless access points to each other as well as to wired devices and the Internet. The different versions of Wi-Fi are specified by various IEEE 802.11 protocol standards, with the different radio technologies determining radio bands, and the maximum ranges, and speeds that may be achieved. Wi-Fi most commonly uses the 2.4 gigahertz (120 mm) UHF and 5 gigahertz (60 mm) SHF radio bands; these bands are subdivided into multiple channels. Channels can be shared between networks but only one transmitter can locally transmit on a channel at any moment in time.
Wi-Fi's wavebands have relatively high absorption and work best for line-of-sight use. Many common obstructions such as walls, pillars, home appliances, etc. may greatly reduce range, but this also helps minimize interference between different networks in crowded environments. An access point (or hotspot) often has a range of about 20 metres (66 feet) indoors while some modern access points claim up to a 150-metre (490-foot) range outdoors. Hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres (miles) using many overlapping access points with roaming permitted between them. Over time the speed and spectral efficiency of Wi-Fi have increased. As of 2019, at close range, some versions of Wi-Fi, running on suitable hardware, can achieve speeds of over 1 Gbit/s (gigabit per second).

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  1. A

    Is There a Small WiFi-Enabled Human Motion Sensor?

    Hello I'm designing a project and i need a sensor that can detect human motion.I would like to detect the output signal of this sensor by searching it via laptop or mobile phone as if they are searching for a wifi signal. I would like to know if such sensor is available or should i build a...
  2. M

    Does a wifi client transmit when not associated?

    Does a wifi client (such as a laptop or phone) transmit anything prior to associating (or attempting to associate) with an AP? I suspect no, but I have searched the web and skimmed various specs and standards and I have not been able to find the answer. If you answer my question, please...
  3. M

    Wifi communication with microcontroller

    Hi, I'm doing a project to send messages from a PC to a micro controller using WiFi. The MCU will intern display the message on an LCD. I have doubts about what devices I should buy to make the wifi communication and also what type of MCU I need to buy?...Any suggestions...
  4. N

    Free WiFi at Airports: Why LAX & DFW Don't Offer It

    I don't know how many of you travel but I am wondering if any of you know the story behind free Wifi at airports? More specifically, why is it that Seattle, Pittsburgh, Phoenix, Tucson, San Francisco, Denver, San Antonio, Boston, Chicago, Detroit, Washington and other major cities offer free...
  5. russ_watters

    Mount Everest Review: No wifi, Rude Yeti = 2 stars

    http://www.cnngo.com/explorations/life/mount-everest-has-no-wi-fi-and-too-much-snow-014380?hpt=Sbin ...and homogenous views: snow, snow and more snow.
  6. L

    Wifi Sector antenna health hazard?

    Hi - the building community where I live has just installed a few Wi-Fi ("sector", I believe) antennas and one of them is at same height and facing straight into my apartment. They are probably 10-15 meters across my apartment. I have a one year old son, and concerned about any health effects...
  7. S

    Amplifying WiFi Signal with an Op Amp: Is It Possible?

    could one attach an op amp to a wifi transmitter to amplify the signal? thanks.
  8. M

    Revolutionize Charging with RCA Airnergy: Harness WiFi Energy Harvesting!

    A little gizmo with one heckuva claim was demonstrated at the Consumer Electronics Show (CES) recently. The Airnergy by RCA claims to be able to scavenge enough energy from WiFi (and presumably the 2.4GHz band) to juice up its own internal battery and allow a user to charge up devices on the...
  9. A

    Wifi n bluetooth technology how?

    wifi n bluetooth technology how?? how can the bluetooth n wi-fi rays or waves can travel even through the walls ...i mean what might be the properties
  10. J

    WiFi Antenna Coupling in Faraday Cage RV - Jack

    Hi - I live full time in an RV that is surrounded by aluminum - essentially a faraday cage, except for a few rather small windows. I'd like to mount a WiFi antenna on the roof and run a cable in a window or thru a small hole. Basic issue - how to get a good signal from a campground WiFi...
  11. L

    Wifi networks. Dangerous for health?

    Wifi networks. Dangerous for health?? Hi, Recently, I have installed a wireless router to create a network at home between 2 computers. This question to say the truth has worried me a bit because searching in the net about this question we can find a lot of opinions warning about the use of...
  12. W

    Host Free WiFi Legal? Cafe Owners Must Know

    Is it legal to host free WiFi access? Especially in places like a cafe if you owned one. Or does one have to pay some additional royalties?
  13. O

    Fixing Strange WIFI Problem: ADSL Connection & WIFI Antenna Box Explained

    I have an ADSL connection to my PC. I bought an ADSL WIFI antenna box so I can receive the high speed internet network on my notebook in the other room or backyard of my house. It works OK, I can even completely turn off my desktop PC and just connet the WIFI box - antenna to power supply and...
  14. O

    Can I Use WIFI with a 56K Modem and Wireless Router?

    I only have a 56 K modem attached to my computer. I have another laptop (or notebook PC) that has a WIFI connection. Is it possible or are there some kinds of routers that allow me to attach the WIFI router - device on the telephone line that communicates at 56 K modem mode and be able to...
  15. C

    WiFi radiation? Is it dangerous for health?

    an anybody explain the effect of electromagnetic signal emitted by wifi hotspot to our health? Is it dangerous? sorry, I'm just being paranoid... :-p
  16. Saint

    Is 11MB/s Wifi Pcmcia Enough for Broadband? College Wireless Considerations

    is 11MB/s sufficient for all broadband? my college goes wireless now, i need to purchase one PCMCIA WIFI or USB2 donggle, 11MB/s can last for how long before obsolete?
  17. A

    WiFi Over Powerlines: Benefits & Challenges

    Hey guys! In a magazine I was reading recently, they mentioned that they are now testing wireless internet over the power lines! They said they've known for years that the powerlines are a great way to do such things, because they are nice copper cables that are run practically...
  18. russ_watters

    Improve WiFi Reception with Phased Array Antenna

    I moved into a new condo last week. It has concrete block walls and concrete floors and ceilings. Needless to say, the wireless reception is terrible. I bought two of http://www.hawkingtech.com/prodSpec.php?ProdID=183 - 90 degree directional antennas. They helped a little, but...
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