Svi moderni korisnici interneta svjesni su pojma Wi-Fi . To je način bežičnog povezivanja na internet. Wi-Fi je zaštitni znak koji je u vlasništvu Wi-Fi Alliance . Ova je organizacija odgovorna za certificiranje Wi-Fi proizvoda ako zadovoljavaju 802.11 bežične standarde koje je postavio IEEE . Koji su to standardi? Oni su u osnovi skup specifikacija koje rastu kako nove frekvencije postaju dostupne. Sa svakim novim standardom, cilj je povećati bežičnu propusnost i domet.

Možda ćete naići na ove standarde ako želite kupiti novu opremu za bežično umrežavanje. Postoji hrpa različitih standarda, svaki sa svojim vlastitim skupom mogućnosti. Samo^(Just) zato što je novi standard objavljen ne znači da je odmah dostupan potrošaču ili da se morate prebaciti na njega. Standard za odabir ovisi o vašim zahtjevima.

Potrošačima je obično teško razumjeti standardne nazive. To je zbog sheme imenovanja koju je usvojio IEEE . Nedavno^(Recently) (2018.) Wi-Fi Alliance je nastojao standardna imena učiniti jednostavnim za korištenje. Stoga su sada smislili lako razumljiva standardna imena/brojeve verzija. Jednostavniji nazivi su, međutim, samo za novije standarde. I, IEEE se još uvijek poziva na standarde koji koriste staru shemu. Stoga je dobra ideja biti upoznat i s IEEE shemom imenovanja.

Objašnjeni standardi Wi-Fi: 802.11ac, 802.11b/g/n, 802.11a

Neki od najnovijih Wi-Fi standarda su 802.11n, 802.11ac i 802.11ax. Ovi nazivi mogu lako zbuniti korisnika. Dakle, nazivi koje je tim standardima dao Wi-Fi Alliance su – Wi-Fi 4 , Wi-Fi 5 i W-Fi 6. Možda ćete primijetiti da svi standardi imaju '802.11' u sebi.

Što je 802.11?^{(What is 802.11? )}

802.11 se može smatrati temeljnim temeljom na kojem su razvijeni svi ostali bežični proizvodi. 802.11 je bio prvi WLAN standard. Stvorio ga je IEEE 1997. Imao je domet od 66 stopa u zatvorenom i 330 stopa na otvorenom. 802.11 bežični proizvodi se više ne proizvode zbog niske propusnosti (teško 2 Mbps ). Međutim, mnogi drugi standardi izgrađeni su oko 802.11.

Pogledajmo sada kako su se Wi-Fi standardi razvili otkako je stvoren prvi WLAN . U nastavku se raspravlja o raznim Wi-Fi standardima koji su se pojavili od 802.11, kronološkim redom.

1. 802.11b

Iako je 802.11 bio prvi WLAN standard ikada, bio je 802.11b koji je učinio Wi-Fi popularnim. 2 godine nakon 802.11, u rujnu 1999.^{(September 1999)} , 802.11b je objavljen. Iako je i dalje koristio istu frekvenciju radio signalizacije od 802.11 (oko 2,4 GHz ), brzina je porasla s 2 Mbps na 11 Mbps . Ovo je još uvijek bila teoretska brzina. U praksi je očekivana propusnost bila 5,9 Mbps (za TCP ) i 7,1 Mbps (za UDP ). Ne samo da je najstariji nego ima i najmanju brzinu među svim standardima. 802.11b imao je domet od oko 150 stopa.

Budući da radi na nereguliranoj frekvenciji, drugi kućanski aparati u rasponu od 2,4 GHz (kao što su pećnice i bežični telefoni) mogu uzrokovati smetnje. Taj je problem izbjegnut postavljanjem opreme na udaljenosti od uređaja koji bi potencijalno mogli izazvati smetnje. 802.11b i njegov sljedeći standard 802.11a odobreni su u isto vrijeme, ali je 802.11b prvi stigao na tržište.

2. 802.11a

802.11a je stvoren u isto vrijeme kada i 802.11b. Dvije tehnologije bile su nekompatibilne zbog razlike u frekvencijama. 802.11a radio je na frekvenciji od 5 GHz što je manje gužve. Tako su šanse za smetnje svedene na minimum. Međutim, zbog visoke frekvencije, 802.11a uređaji imali su manji domet i signali ne bi lako probijali prepreke.

802.11a koristio je tehniku ​​zvanu Ortogonalno frekvencijsko multipleksiranje (OFDM)^{(Orthogonal Frequency Division Multiplexing (OFDM))} za stvaranje bežičnog signala. 802.11a je također obećavao mnogo veću propusnost – teoretski maksimum od 54 Mbps . Kako su 802.11a uređaji u to vrijeme bili skuplji, njihova je upotreba bila ograničena na poslovne aplikacije. 802.11b je bio standard koji je prevladavao među običnim ljudima. Stoga je popularniji od 802.11a.

3. 802.11g

802.11g odobren je u lipnju 2003. godine^{(June 2003)} . Standard je pokušao kombinirati prednosti posljednja dva standarda – 802.11a i 802.11b. Dakle, 802.11g osigurava propusnost od 802.11a (54 Mbps ). Ali pružao je veći domet radeći na istoj frekvenciji kao 802.11b (2,4 GHz ). Dok posljednja dva standarda nisu međusobno kompatibilna, 802.11g je kompatibilan s 802.11b unatrag. To znači da se bežični mrežni adapteri 802.11b mogu koristiti s pristupnim točkama 802.11g.

Ovo je najjeftiniji standard koji se još uvijek koristi. Iako pruža podršku za gotovo sve bežične uređaje koji se danas koriste, ima nedostatak. Ako su povezani neki 802.11b uređaji, cijela mreža usporava kako bi odgovarala svojoj brzini. Dakle^(Thus) , osim što je najstariji standard u upotrebi, on je i najsporiji.

Ovaj standard bio je značajan korak prema boljoj brzini i pokrivenosti. To je bilo vrijeme kada su potrošači izjavili da uživaju u usmjerivačima^(routers) s boljom pokrivenošću od prethodnih standarda.

4. 802.11n

Ovaj standard je također nazvan Wi-Fi 4 od strane Wi-Fi Alliancea^(Alliance) , a odobren je u listopadu 2009. godine^{(October 2009)} . Bio je to prvi standard koji je koristio MIMO tehnologiju. MIMO je skraćenica od Multiple Input Multiple Output^{(MIMO stands for Multiple Input Multiple Output)} . U ovom rasporedu, mnogi odašiljači i prijemnici rade ili na jednom kraju ili čak na oba kraja veze. Ovo je veliki razvoj jer više ne morate ovisiti o većoj propusnosti ili snazi ​​prijenosa za povećanje podataka.

Uz 802.11n, Wi-Fi je postao još brži i pouzdaniji. Možda ste čuli izraz dual-band od LAN dobavljača. To znači da se podaci isporučuju na 2 frekvencije. 802.11n radi na 2 frekvencije – 2,45 GHz i 5 GHz . 802.11n ima teoretsku propusnost od 300 Mbps . Vjeruje se da brzine mogu doseći čak 450 Mbpsako se koriste 3 antene. Zbog signala visokog intenziteta, 802.11n uređaji pružaju veći domet u usporedbi s onima prijašnjih standarda. 802.11 pruža podršku za širok raspon bežičnih mrežnih uređaja. Međutim, skuplji je od 802.11g. Također, kada se koristi u bliskoj udaljenosti s 802.11b/g mrežama, može doći do smetnji zbog upotrebe više signala.

Također pročitajte: ^{(Also Read:)} Što je Wi-Fi 6 (802.11 ax)?^{(What is Wi-Fi 6 (802.11 ax)?)}

5. 802.11ac

Izdan 2014. godine, ovo je najčešći standard koji se danas koristi. 802.11ac je od Wi-Fi Alliancea^(Alliance) dobio ime Wi-Fi 5 . Današnji kućni bežični usmjerivači kompatibilni su s Wi-Fi 5 i rade na frekvenciji od 5 GHz. Koristi MIMO , što znači da postoji više antena na uređajima za slanje i primanje. Smanjena je pogreška i velika brzina. Ovdje je posebnost u tome što se koristi višekorisnički MIMO . To ga čini još učinkovitijim. U MIMO -u mnogi su tokovi usmjereni na jednog klijenta. U MU-MIMO, prostorni tokovi mogu biti usmjereni na više klijenata u isto vrijeme. To možda neće povećati brzinu jednog klijenta. Ali ukupna propusnost podataka mreže značajno je povećana.

Standard podržava višestruke veze na oba frekvencijska pojasa na kojima radi – 2,5 GHz i 5 GHz . 802.11g podržava četiri toka dok ovaj standard podržava do 8 različitih tokova kada radi u frekvencijskom pojasu od 5 GHz .

802.11ac implementira tehnologiju zvanu oblikovanje zraka. Ovdje antene odašilju radio signale tako da su usmjereni na određeni uređaj. Ovaj standard podržava brzine prijenosa podataka do 3,4 Gbps . Ovo je prvi put da je brzina podataka porasla na gigabajte. Ponuđena širina pojasa je oko 1300 Mbps u pojasu od 5 GHz i 450 Mbps u pojasu od 2,4 GHz .

Standard pruža najbolji domet i brzinu signala. Njegove performanse su jednake standardnim žičanim vezama. Međutim, poboljšanje performansi može se vidjeti samo u aplikacijama velike propusnosti. Također, to je najskuplji standard za implementaciju.

Ostali Wi-Fi standardi^{(Other Wi-Fi standards)}

1. 802.11ad

Standard je uveden u prosincu 2012. godine^{(December 2012)} . To je iznimno brz standard. Radi nevjerojatnom brzinom od 6,7 Gbps . Radi na frekvencijskom pojasu od 60 GHz . Jedini nedostatak je njegov mali domet. Navedena brzina može se postići samo kada se uređaj nalazi u radijusu od 11 stopa od pristupne točke.

2. 802.11ah

802.11ah je također poznat kao Wi-Fi HaLow . Odobren je u rujnu 2016.^{(September 2016)} i objavljen u svibnju 2017. godine^{(May 2017)} . Cilj je osigurati bežični standard koji pokazuje nisku potrošnju energije. Namijenjen je za Wi-Fi mreže koje nadilaze opseg uobičajenih 2,4 GHz i 5 GHz pojasa (osobito one mreže koje rade ispod 1 GH pojasa). U ovom standardu, brzine podataka mogu ići do 347 Mbps . Standard je namijenjen niskoenergetskim uređajima kao što su IoT uređaji. Uz 802.11ah moguća je komunikacija na velikim udaljenostima bez velike potrošnje energije. Vjeruje se da će se standard natjecati s Bluetoothom^(Bluetooth)tehnologija.

3. 802.11aj

To je malo izmijenjena verzija standarda 802.11ad. Namijenjen je za upotrebu u regijama koje rade u opsegu 59-64 GHz (prvenstveno Kina^(China) ). Dakle, standard ima i drugo ime - Kineski milimetarski val^{(China Millimeter Wave)} . Radi u kineskom pojasu od 45 ^{(China 45)} GHz , ali je unatrag kompatibilan sa 802.11ad.

4. 802.11ak

802.11ak ima za cilj pružiti pomoć s internim vezama unutar 802.1q mreža, za uređaje koji imaju mogućnost 802.11. U studenom 2018.^{(November 2018)} standard je imao status nacrta. Namijenjen je za kućnu zabavu i druge proizvode s 802.11 mogućnošću i 802.3 ethernet funkcijom.

5. 802.11ay

Standard 802.11ad ima propusnost od 7 Gbps . 802.11ay, također poznat kao sljedeća generacija 60 GHz, ima za cilj postići propusnost do 20 Gbps u frekvencijskom pojasu od 60 GHz. Dodatni ciljevi su – povećanje dometa i pouzdanosti.

6. 802.11ax

Popularno poznat kao Wi-Fi 6, ovo će biti nasljednik Wi-Fi 5 . Ima mnoge prednosti u odnosu na Wi-Fi 5 , kao što su bolja stabilnost u prepunim područjima, velika brzina čak i kada je više uređaja povezano, bolje oblikovanje zraka, itd... To je visokoučinkoviti WLAN . Očekuje se da će pružiti izvrsne performanse u gustim regijama kao što su zračne luke. Procijenjena brzina je najmanje 4 puta veća od trenutne brzine u Wi-Fi 5 . Radi u istom spektru – 2,4 GHz i 5 GHz . Budući da također obećava bolju sigurnost i troši manje energije, svi budući bežični uređaji bit će proizvedeni tako da budu kompatibilni s Wi-Fi 6.

Preporučeno: ^{(Recommended:)} Koja je razlika između usmjerivača i modema?^{(What is the Difference Between a Router and a Modem?)}

Sažetak^(Summary)

• Wi-Fi standardi skup su specifikacija za bežično povezivanje.
• Ove standarde uvodi IEEE , a certificira i odobri Wi-Fi Alliance .
• Mnogi korisnici nisu svjesni ovih standarda zbog zbunjujuće sheme imenovanja koju je usvojio IEEE .
• Kako bi korisnicima bilo jednostavnije, Wi-Fi Alliance je prekrstio neke najčešće korištene Wi-Fi standarde s nazivima prilagođenim korisnicima.
• Sa svakim novim standardom, postoje dodatne značajke, bolja brzina, veći domet itd.
• Danas najčešće korišteni Wi-Fi standard je Wi-Fi 5.

Wi-Fi Standards Explained: 802.11ac, 802.11b/g/n, 802.11a

All modern internet usеrs are aware of the term Wi-Fi. It iѕ a wаy to connect to the internet wirelessly. Wi-Fi is a trademark that is owned by the Wi-Fi Alliance. Τhis organization is responsible for certifying Wi-Fi prоducts if they meet the 802.11  wireless standards ѕet by the IEEE. What are these standardѕ? They are basically a set of specifications that keep growing as new frequencies become available. With every new standard, the aim is to boost the wireless throughput and range.

You may come across these standards if you are looking to buy new wireless networking gear. There are a bunch of different standards each with their own set of capabilities. Just because a new standard has been released does not mean that it is immediately available to the consumer or you need to switch over to it. The standard to choose depends on your requirements.

Consumers usually find the standard names hard to understand. That is because of the naming scheme adopted by the IEEE. Recently (in 2018), the Wi-Fi Alliance aimed to make the standard names user-friendly. Thus, they have now come up with easy-to-understand standard names/version numbers. The simpler names are, however, only for the recent standards. And, IEEE still refers to the standards using the old scheme. Thus, it is a good idea to be familiar with the IEEE naming scheme too.

Wi-Fi Standards Explained: 802.11ac, 802.11b/g/n, 802.11a

Some of the recent Wi-Fi standards are 802.11n, 802.11ac, and 802.11ax. These names can easily confuse the user. Thus, the names given to these standards by the Wi-Fi Alliance are – Wi-Fi 4, Wi-Fi 5, and W-Fi 6. You may notice that all the standards have ‘802.11’ in them.

What is 802.11?

802.11 can be considered as the basic foundation upon which all other wireless products were developed. 802.11 was the first WLAN standard. It was created by IEEE in 1997. It had a 66-feet indoor range and a 330-feet outdoor range. 802.11 wireless products are no longer made because of its low bandwidth (hardly 2 Mbps). However, many other standards have been built around 802.11.

Let us now take a look at how the Wi-Fi standards have evolved since the first WLAN was created. Discussed below are the various Wi-Fi standards that came up since 802.11, in chronological order.

1. 802.11b

Although 802.11 was the first WLAN standard ever, it was 802.11b which made Wi-Fi popular. 2 years after 802.11, in September 1999, 802.11b was released. While it still used the same radio signaling frequency of 802.11 (about 2.4 GHz), the speed went up from 2 Mbps to 11 Mbps. This was still the theoretical speed. In practice, the expected bandwidth was 5.9 Mbps (for TCP) and 7.1 Mbps (for UDP). It is not only the oldest but also has the least speed among all the standards. 802.11b had a range of about 150 feet.

As it operates at an unregulated frequency, other home appliances at 2.4 GHz range (such as ovens and cordless phones) can cause interference. This problem was avoided by installing the gear at a distance from appliances that could potentially incur interference. 802.11b and its next standard 802.11a were both approved at the same time, but it was 802.11b that hit the markets first.

2. 802.11a

802.11a was created at the same time as 802.11b. The two technologies were incompatible because of the difference in frequencies. 802.11a operated at a 5GHz frequency which is less crowded. Thus, the chances of interference were minimized. However, due to high frequency, 802.11a devices had a lesser range and the signals would not penetrate obstructions easily.

802.11a used a technique called Orthogonal Frequency Division Multiplexing (OFDM) to create a wireless signal. 802.11a also promised a much higher bandwidth – a theoretical maximum of 54 Mbps. As 802.11a devices were more expensive at the time, their use was restricted to business applications. 802.11b was the standard prevalent among the common people. Thus, it has more popularity than 802.11a.

3. 802.11g

802.11g was approved in June 2003. The standard made an attempt to combine the benefits provided by the last two standards – 802.11a & 802.11b. Thus, 802.11g provided the bandwidth of 802.11a (54 Mbps). But it provided a greater range by operating at the same frequency as 802.11b (2.4 GHz). While the last two standards were incompatible with each other, 802.11g is backward compatible with 802.11b. This means that 802.11b wireless network adapters can be used with 802.11g access points.

This is the least expensive standard that is still in use. While it provides supports for almost all the wireless devices in use today, it does have a disadvantage. If there are any 802.11b devices connected, the whole network slows down to match its speed. Thus, apart from being the oldest standard in use, it is the slowest as well.

This standard was a significant leap towards better speed and coverage. This was the time when consumers stated enjoying routers with better coverage than the previous standards.

4. 802.11n

Also named Wi-Fi 4 by the Wi-Fi Alliance, this standard was approved in October 2009. It was the first standard that made use of MIMO technology. MIMO stands for Multiple Input Multiple Output. In this arrangement, many transmitters and receivers operate either at one end or even at both ends of the link. This is a major development because you no more have to depend on higher bandwidth or transmit power for an increase in data.

With 802.11n, Wi-Fi became even faster and more reliable. You might have heard the term dual-band from LAN vendors. This means that data is delivered across 2 frequencies. 802.11n operates at 2 frequencies – 2.45 GHz and 5 GHz. 802.11n has a theoretical bandwidth of 300 Mbps. It is believed that the speeds can reach even 450 Mbps if 3 antennae are used. Due to signals of high intensity, 802.11n devices provide a greater range when compared to those of previous standards. 802.11 provides support for a wide range of wireless network devices. However, it is more expensive than 802.11g. Also, when used in close range with 802.11b/g networks, there may be interference due to the use of multiple signals.

Also Read: What is Wi-Fi 6 (802.11 ax)?

5. 802.11ac

Released in 2014, this is the most common standard in use today. 802.11ac was given the name Wi-Fi 5 by the Wi-Fi Alliance. The home wireless routers today are Wi-Fi 5 compliant and operate at 5GHz frequency. It makes use of MIMO, which means there are multiple antennas on sending and receiving devices. There is reduced error and high speed. The specialty here is, a multi-user MIMO is used. This makes it even more efficient. In MIMO, many streams are directed to a single client. In MU-MIMO, spatial streams can be directed to many clients at the same time. This may not increase the speed of a single client. But the overall data throughput of the network is significantly increased.

The standard supports multiple connections on both the frequency bands at which it operates – 2.5 GHz and 5 GHz. 802.11g supports four streams while this standard supports up to 8 different streams when it operates in the 5 GHz frequency band.

802.11ac implements a technology called beamforming. Here, the antennae transmit radio signals such that they are directed at a specific device. This standard supports data rates up to 3.4 Gbps. This is the first time the data speed has risen to gigabytes. The bandwidth offered is around 1300 Mbps in the 5 GHz band and 450 Mbps in the 2.4 GHz band.

The standard provides the best signal range and speed. Its performance is on par with standard wired connections. However, the improvement in performance can be seen only in high-bandwidth applications. Also, it is the most expensive standard to implement.

Other Wi-Fi standards

1. 802.11ad

The standard was rolled out in December 2012. It is an extremely fast standard. It operates at an unbelievable speed of 6.7 Gbps. It operates at the 60 GHz frequency band. The only disadvantage is its short range. The said speed can be achieved only when the device is situated within an 11 feet radius from the access point.

2. 802.11ah

802.11ah is also known as Wi-Fi HaLow. It was approved in September 2016 and released in May 2017. The aim is to provide a wireless standard that exhibits low energy consumption. It is meant for Wi-Fi networks that go beyond the reach of the usual 2.4 GHz and 5 GHz bands (especially those networks that operate below the 1 GH band). In this standard, data speeds can go up to 347 Mbps. The standard is meant for low-energy devices such as IoT devices. With 802.11ah, communication across long ranges without consuming much energy is possible. It is believed that the standard will compete with Bluetooth technology.

3. 802.11aj

It is a slightly modified version of the 802.11ad standard. It is meant for use in regions that operate in the 59-64 GHz band (primarily China). Thus, the standard also has another name – the China Millimeter Wave. It operates in the China 45 GHz band but is backward compatible with 802.11ad.

4. 802.11ak

802.11ak aims to provide help with internal connections within 802.1q networks, to devices that have 802.11 capability. In November 2018, the standard had a draft status. It is meant for home entertainment and other products with 802.11 capability and 802.3 ethernet function.

5. 802.11ay

The 802.11ad standard has a throughput of 7 Gbps. 802.11ay, also known as the next-generation 60GHz, aims to achieve a throughput of up to 20 Gbps in the 60GHz frequency band. Additional objectives are – increased range and reliability.

6. 802.11ax

Popularly known as Wi-Fi 6, this will be the successor of Wi-Fi 5. It has many benefits over Wi-Fi 5, such as better stability in crowded areas, high speed even when multiple devices are connected, better beamforming, etc… It is a high-efficiency WLAN. It is expected to provide excellent performance in dense regions such as airports. The estimated speed is at least 4 times more than the current speed in Wi-Fi 5. It operates in the same spectrum – 2.4 GHz and 5 GHz. Since it also promises better security and consumes lesser power, all future wireless devices will be manufactured such that they are Wi-Fi 6 compliant.

Recommended: What is the Difference Between a Router and a Modem?

Summary

• Wi-Fi standards are a set of specifications for wireless connectivity.
• These standards are introduced by the IEEE and certified and approved by the Wi-Fi Alliance.
• Many users are not aware of these standards due to the confusing naming scheme adopted by the IEEE.
• To make it simpler for the users, the Wi-Fi Alliance has re-christened some commonly used Wi-Fi standards with user-friendly names.
• With every new standard, there are additional features, better speed, longer range, etc.
• The most commonly used Wi-Fi standard today is Wi-Fi 5.

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