Wi-fi gets quicker with 802.11ax

The lat­est Wi-fi stan­dard makes home net­works faster, es­pe­cially for video stream­ing.

Macworld (USA) - - Contents - BY GLENN FLEISHMAN

Wi-fi net­work­ing is poised for a ma­jor up­date: The tran­si­tion from 802.11ac to 802.11ax prom­ises a mod­ern net­work­ing hub that can cope with the bur­geon­ing num­ber and di­ver­sity of wire­less de­vices that need ac­cess to your broad­band con­nec­tion.

At the dawn of the mod­ern smart­phone era in 2007, even a highly un­plugged home might have only a hand­ful of hard­ware con­nect­ing to its wire­less router.

Now—if you use tablets, smart-home de­vices, me­dia stream­ers, smart TVS, gam­ing gear and se­cu­rity cam­eras—you could have 20, 30, or many more. And that num­ber won’t get smaller in the fu­ture.

With 802.11ax, the IEEE en­gi­neer­ing group that drives stan­dards like wire­less lo­cal area net­work­ing (WLAN) has pushed hard in sev­eral direc­tions to make these com­pli­cated en­vi­ron­ments work. There are a lot of ben­e­fits for dense cor­po­rate net­works that need mas­sive through­put and could have tens of thou­sands of roam­ing and fixed Wi-fi clients, but there’s no short­age of up­sides for home users or small of­fices, es­pe­cially when it comes to video stream­ing and file trans­fers.

Cor­po­ra­tions also con­trol the wire­less net­works in their build­ings and through­out their cam­puses, while home users and small busi­nesses can face sev­eral to dozens of net­works within ra­dio earshot. Sev­eral tech­niques in 802.11ax will re­duce the ef­fects of in­ter­fer­ence and in­crease through­put in crowded ur­ban and sub­ur­ban en­vi­ron­ments, re­duc­ing typ­i­cal frus­tra­tions that are hard to trou­bleshoot or fix.

The stan­dard hasn’t been com­pleted yet, but man­u­fac­tur­ers are jump­ing the gun as they have with ev­ery new flavor of Wi-fi for more 15 years. As a re­sult, some equip­ment could be on the mar­ket as early as June, and more is com­ing later in the year. But the ad­van­tages of be­ing an early adopter might pale in fa­vor of wait­ing for a fully baked ver­sion that’s sta­ble and is sup­ported by the client adapters on­board phones, lap­tops, and other gear.

HOW 802.11AX MAKES GAINS

To ex­plain the ad­van­tages of 802.11ax, we must drill down briefly to re­view how Wi-fi

works. The air­waves are reg­u­lated nearly ev­ery­where in the world, and in the U.S. and in most coun­tries, two chunks of fre­quen­cies are al­lot­ted to uses com­pat­i­ble with Wi-fi: the 2.4 gi­ga­hertz (GHZ) band and the 5GHZ band. These bands are fur­ther di­vided into chan­nels that have a set start­ing and end­ing fre­quency.

Senders and re­ceivers, like a Wi-fi router and lap­top, agree to use the same chan­nel to com­mu­ni­cate back and forth, and dozens (or even hun­dreds) of de­vices can use the same chan­nel at the same time to re­lay data via an ac­cess point. In cities and sub­urbs, dozens to hun­dreds of net­works might also be con­tend­ing for the same chan­nel in rel­a­tively close prox­im­ity.

Way back in 1999, the 802.11a stan­dard for 5GHZ and 802.11b for 2.4GHZ started the WLAN rev­o­lu­tion, of­fer­ing data rates of

54- and 11Mbps, re­spec­tively. These rates were al­ways the max­i­mum pos­si­ble and in­cluded net­work over­head, so de­vices saw of­ten 40- to 90-per­cent less through­put.

Wi-fi ad­vanced through 802.11g (2.4GHZ), 802.11n (2.4GHZ and 5GHZ), and two re­leases of 802.11ac (5GHZ) Wave 1 and Wave 2. The 802.11ax stan­dard im­proves per­for­mance in both spec­trum bands, and will de­liver po­ten­tially sev­eral gi­ga­bits per sec­ond of through­put to dozens of de­vices at once on a sin­gle chan­nel. That’s in­cred­i­bly helpful if you’re stream­ing com­pressed HD and 4K HDR video or trans­fer­ring multi-gi­ga­byte files around a net­work. An in­creas­ing num­ber of peo­ple world­wide have 100Mbps to 1Gbps broad­band con­nec­tions, which can be con­strained by slower Wi-fi net­works.

Each suc­ces­sive up­date to Wi-fi has pushed data rates higher, but 802.11ax of­fers a huge boost by adding sev­eral var­ied tech­niques, each of which adds a unique ad­van­tage. Taken to­gether, the max­i­mum raw data rate across an 802.11ax base sta­tion (e.g., a Wi-fi router) could be a whop­ping 14Gbps com­pared to just 3.5Gbps for the best sim­i­larly con­fig­ured 802.11ac router. In

prac­tice, you will never see that max­i­mum po­ten­tial speed, but 802.11ax is still poised to of­fer mul­ti­ple times the rates of 802.11ac, and will bet­ter meet solid re­quire­ments for video with many peo­ple stream­ing or trans­fer­ring files at once.

Here’s a top-level run­down of how 802.11ax pulls this off:

DENSER DATA EN­COD­ING

Wi-fi en­codes data into ra­dio waves, and there are cal­cu­la­ble lim­its to how much data can be car­ried at a given fre­quency. WLAN stan­dards, how­ever, are still work­ing to­ward that up­per max­i­mum. Over time, the chips that process sig­nals have be­come more pow­er­ful, al­low­ing more ef­fi­cient cram­ming of data into the same space, es­pe­cially over very short dis­tances be­tween a base sta­tion and a re­ceiv­ing de­vice, typ­i­cally in the same room and with line of sight, which is per­fect for video stream­ing.

802.11ac started down this path, al­low­ing en­cod­ings with 33 per­cent more data than 802.11n; 802.11ax bumps that up an­other 25 per­cent. As an anal­ogy, con­sider egg car­tons made up of squares with an in­set cir­cle for eggs, ar­ranged in rows and col­umns. Now, re­place the square with a hexag­o­nal grid with less card­board be­tween each egg. That might re­sult in more bro­ken eggs, just at these densely packed wire­less sig­nals can suf­fer some loss via er­ror, but you typ­i­cally wind up with many more eggs.

ADDING 2.4GHZ BACK INTO THE MIX

The 2.4GHZ band is of­ten given shorter shrift, be­cause it’s crowded full of other so-called un­li­censed uses that rely on wire­less data—like baby mon­i­tors, wire­less door­bells, cord­less phones, and the like—that don’t play well with high-speed Wi-fi net­works. Many of those non-wi-fi

uses have shifted to other bands or now rely on Wi-fi. 802.11ax is the first stan­dard in more than a decade that im­proves per­for­mance in 2.4GHZ, which opens up as many as gi­ga­bits per sec­ond more data while also tak­ing ad­van­tage of that band’s long wave­lengths com­pared to 5GHZ: longer wave­lengths bet­ter pen­e­trate solids ob­jects, like walls, floors, and fur­ni­ture.

This is es­pe­cially use­ful for mesh net­works, in which cur­rent mesh nodes typ­i­cally have two ra­dios, one for 2.4GHZ and one for 5GHZ, one of which is used to com­mu­ni­cate among nodes. With much higher data rates on the bet­ter­pen­e­trat­ing 2.4GHZ band, mesh net­work­ing with 802.11ax will re­sult in bet­ter through­put across a whole net­work.

TALK­ING AND LIS­TEN­ING TO MUL­TI­PLE DE­VICES AT ONCE

The 802.11n stan­dard added a spa­tial mul­ti­plex­ing tech­nol­ogy known as MIMO (mul­ti­ple in, mul­ti­ple out). MIMO is a means of send­ing mul­ti­ple streams of data across dif­fer­ent phys­i­cal paths, like play­ing bil­liards with ra­dio waves. This re­quired mul­ti­ple send­ing and re­ceiv­ing an­ten­nas and the equiv­a­lent of ad­di­tional ra­dios for each stream. But many de­vices, es­pe­cially small mo­bile and smart-home units, didn’t have mul­ti­ple ra­dios. A wire­less router with MIMO thus wastes much of its po­ten­tial band­width at any given time when it’s con­strained to a sin­gle stream.

Start­ing with 802.11ac, routers gained the abil­ity to talk si­mul­ta­ne­ously with dif­fer­ent de­vices at the same time (mul­ti­ple-user or MU-MIMO), im­prov­ing ef­fi­ciency. In 802.11ax, client de­vices can now also re­spond si­mul­ta­ne­ously. That’s ex­tremely helpful for stream­ing me­dia play­ers, al­low­ing more reli­able au­dio and video play­back to first pass from the player to the router, and then from the router to your view­ing or lis­ten­ing

de­vice (e.g., your smart TV, me­dia streamer, or smart­phone, or dig­i­tal au­dio player). 802.11ax also dou­bles the num­ber of pos­si­ble streams from four to eight, but that fea­ture is likely to be seen only on ex­pen­sive en­ter­prise equip­ment, not home de­vices.

SUBCHANNELS

Bor­row­ing a trick from 4G LTE and a few ear­lier stan­dards, 802.11ax adds a way to break a Wi-fi chan­nel down into as many as a cou­ple thou­sand tightly spaced “sub­car­ri­ers” or subchannels. Each of these subchannels can carry var­i­ous com­bined pay­loads of data for dif­fer­ent de­vices, and in­ter­fer­ence or noise in one sub­chan­nel is iso­lated from the rest, re­duc­ing the need to re­trans­mit or slow down the en­tire con­ver­sa­tion to a lower data rate that can be re­ceived clearly. (This tech is called Orthog­o­nal Fre­quency Divi­sion Mul­ti­ple Ac­cess or OFDMA.)

You might think of this as the dif­fer­ence be­tween hav­ing one gi­ant truck with a sin­gle large pack­ing con­tainer in­side oc­cu­py­ing an en­tire high­way, and many smaller trucks with very thin di­viders be­tween lanes car­ry­ing a

va­ri­ety of boxes trav­el­ing on the same high­way. An­a­lysts and man­u­fac­tur­ers say that in the right cir­cum­stances, OFDMA could al­low four times the through­put as with cur­rent net­works.

BET­TER DIS­CRIM­I­NA­TION OF OTHER NET­WORKS

In many cities and sub­urbs, dozens to hun­dreds of Wi-fi net­works over­lap. 802.11ax in­cludes a tech­nique that will let the stan­dard dis­crim­i­nate be­tween the net­work you’re on and weakly re­ceived sig­nals from other net­works, which in turn al­lows greater through­put.

A HOST OF SMALLER TECH­NI­CAL IM­PROVE­MENTS

While the el­e­ments above might seem tech­ni­cal enough, a num­ber of other small im­prove­ments add up, in­clud­ing letting 802.11ax break up data for a sin­gle des­ti­na­tion into dif­fer­ent sized chunks to fit into avail­able slots, us­ing longer runs of en­coded data, and bet­ter fo­cus­ing en­ergy for “beam­form­ing” ( go.mac­world.com/ bmfm) to tar­get re­ceiv­ing de­vices more ex­actly. 802.11ax is also bet­ter at avoid­ing con­flicts where de­vices talk over one an­other, called con­tention.

IM­PROVED CLIENT BAT­TERY PER­FOR­MANCE

Here’s one more bonus that’s not re­lated to speed: Var­i­ous mo­bile-tar­geted im­prove­ments, in­clud­ing one that tells net­work client de­vices that put their Wi-fi ra­dios to sleep to con­serve power when ex­actly to wake them up. This could dra­mat­i­cally re­duce Wi-fi-re­lated power con­sump­tion, ex­tend­ing bat­tery life.

THE RISKS FOR EARLY ADOPTERS

While the stan­dard is still un­der devel­op­ment at the IEEE task group, some man­u­fac­tur­ers are prep­ping for the near-term re­lease of Wi-fi routers that will be la­beled 802.11ax, even though they’re us­ing a pre­lim­i­nary ver­sion of the spec as in­ter­preted by a sin­gle man­u­fac­turer or chip­maker. D-link ( go.mac­world.com/dnax) and Asus an­nounced routers at CES in Jan­uary, and as chip­mak­ers get close to fi­nal­iz­ing 802.11ax chipsets, we’ll see more man­u­fac­tur­ers start to make their plans.

Buy­ing early could come with a cost. With the last few rounds of stan­dards, changes were sig­nif­i­cant but con­strained, and few routers had is­sues with ob­tain­ing up­dates to bring them into full com­pli­ance. 802.11ax, how­ever, has so many sub­stan­tive im­prove­ments and dif­fer­ences that it’s pos­si­ble early routers won’t be as ro­bust and com­pli­ant as ones cre­ated us­ing later gen­er­a­tions of chips. Man­u­fac­tur­ers and chip­mak­ers sit on the IEEE com­mit­tee mak­ing de­ci­sions and are part of the Wi-fi

Al­liance that cer­ti­fies prod­ucts as in­ter­op­er­a­ble, but it’s still a risk.

Few of 802.11ax’s ad­van­tages can ac­crue with­out new client adapters in phones, tablets, com­put­ers, and other de­vices, and those al­ways come more slowly as new gen­er­a­tions of equip­ment are in­tro­duced. While 2019 will likely be the year that 802.11ax starts to ap­pear in hun­dreds of mil­lions of new de­vices, it will still eas­ily be two or three years be­fore you have enough new equip­ment to take full ad­van­tage of the new tech­nol­ogy.

Back­ward com­pat­i­bil­ity is al­ways a con­cern for new gen­er­a­tions of hard­ware, but the his­tory of Wi-fi has largely en­com­passed all pre­vi­ous stan­dards with­out too much com­pro­mise. Routers that de­clare them­selves as sup­port­ing 802.11ax will also seam­lessly han­dle ev­ery pre­vi­ous 802.11 stan­dard, typ­i­cally back to 802.11g, the first ver­sion to sup­port more mod­ern net­work se­cu­rity meth­ods. With few ex­cep­tions, you can keep us­ing all the de­vices you used in the past.

You won’t need to con­fig­ure any­thing spe­cial to en­able back­wards com­pat­i­bil­ity, although some routers may have modes you can turn on that dis­able older forms of Wi-fi. Com­pat­i­bil­ity comes with an over­head cost, and turn­ing off older modes can boost per­for­mance some­what. ■

You could think of data trav­el­ing over your Wi-fi net­work as if it were the cargo car­ried by big rigs. In some of the ear­lier Wi-fi stan­dards, each truck could carry only one type of cargo, even if the truck was only par­tially full.

Con­tin­u­ing with the big-rig anal­ogy above, the 802.11ax stan­dard al­lows each big rig to carry dif­fer­ent types of cargo so that all of its ca­pac­ity can be uti­lized.

MU-MIMO al­lows Wi-fi routers and ac­cess points to com­mu­ni­cate si­mul­ta­ne­ously with mul­ti­ple de­vices, re­duc­ing wasted parts of trans­mis­sions.

OFDMA (Orthog­o­nal Fre­quency Divi­sion Mul­ti­ple Ac­cess) al­lows min­gling data for dif­fer­ent re­ceiv­ing de­vices across trans­mis­sions, like pack­ing a truck full by com­bin­ing pal­ettes of boxes in­tended for dif­fer­ent re­cip­i­ents.

D-link’s AX6000 will be one of the first 802.11ax routers to hit the mar­ket.

802.11ax en­ables large num­bers of clients on a home Wi-fi net­work to op­er­ate si­mul­ta­ne­ously with­out de­grad­ing video-stream­ing and other de­vices that re­quire lots of band­width.

Asus in­tends to be early to the 802.11ax router mar­ket with its RT-AX88U Wi-fi router.

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