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Wifi

Comparaison des normes Wireless

Réseaux : Entre les différents réseaux mobiles (EDGE/3G/3G+/H+/4G/4G+) et wifi (a/b/g/n/ac), il n’est pas toujours évident de faire le tri. Plongée au cœur du méandre hertzien.

La mobilité est la norme. Plus un appareil ne sort aujourd’hui sans une connectivité sans fil. Mais entre l’évolution des réseaux de téléphonie mobile et celle des réseaux wifi, les utilisateurs ont parfois du mal à s’y retrouver. Entre une connexion H+ et 4G ou entre un wifi A ou AC, les performances peuvent pourtant être drastiquement différentes et répondre à des usages bien distincts. Récapitulatif en images.

jungle-reseau-sans-fil-580

LTE-U, Wi-Fi Play Nice in Test

SAN FRANCISCO – Qualcomm wants to convince unbelievers that LTE-Unlicensed (LTE-U) will be a good neighbor to Wi-Fi for next generation communications. Following debate about the realities of sharing spectrum, the chip giant discussed coexistence tests conducted at its San Diego lab.

LTE-U aims to extend LTE Advanced to unlicensed 5 GHz spectrum, boosting cellular data speeds over short distances without requiring users to login to a Wi-Fi network. The technology has met with criticism from companies who rely on Wi-Fi and worry about LTE-U inference.

As a test, Qualcomm configured nine access points for media streaming and did not try to counterbalance interference. Engineers measured the throughput of each access point when using Wi-Fi only, then measured again with eight APs configured for Wi-Fi and one using LTE-U over 5 GHz.

Qualcomm found –- and third party firm Signal Research confirmed –- that Wi-Fi access points from different OEMs had variable throughput speeds regardless of the presence of absence of a cellular connection, and LTE-U shared spectrum when it was turned on. The average throughput for the top two access points was 5.8 Mbits/second using all Wi-Fi communications. Using a mix of Wi-Fi with LTE-U, LTE-U use decreased downlink delay by 0.06 milliseconds and increased the uplink delay by 10 milliseconds though LTE-U over 5 GHz has yet to include uplink in its spec.

“LTE-U is inherently a good neighbor to Wi-Fi,” said Mingxi Fan Qualcomm’s vice president of engineering and corporate R&D.

When deployed the technology will rely heavily on small cells and an improved air interface to listen for unused spectrum to offload data to LTE-U, Fan said. In addition, Qualcomm has designed LTE-U chips with “variable on” modes or tiny gaps in use that allow the channels to complete throughput without interference and with low latency, he added.

“[LTE-U is] a great new technology that has tremendous performance advantages for consumers and it coexists very, very well with Wi-Fu,” said Dean Brenner, Qualcomm’s senior vice president of government affairs. “We envision a very long future for Wi-Fi; this is not replacing Wi-Fi.”

The Wi-Fi Alliance recently submitted a request to the FCC requesting additional information about LTE-U and its cousin Licensed Assisted Access (LAA) — a form of unlicensed cellular that will be deployed in Europe and Japan with LTE release 13. The Allaince and others fear unlicensed cellular will degrade performance of services delivered over Wi-Fi. To the contrary, Qualcomm claims that Wi-Fi throughput would improve with more LTE-U access points in use than Wi-Fi but did not provide details.

“I think there is fear, uncertainty, and competitive aspects. Basically there’s a lot of trepidation,” Brenner said. “So we’re doing everything we can to show that this is how it works, how we’ve designed LTE-U for coexistence.”

A Verizon official said the company expects to have small cell technology commercially available in late 2016. Qualcomm will host field trials of this technology alongside its LTE-U capable Snapdragon 820 chip in October 2015.

In the meantime, Qualcomm’s Brenner said the company has weekly conference calls with the Wi-Fi Alliance and will present at an Alliance-sponsored coexistence workshop in November.

— Jessica Lipsky, Associate Editor, EE TimesCircle me on Google+

LWA offers aggregation without the aggravation: the alternative acronym to LTE-U and LAA

wifi-pole

  • LAA/LTE-U needs to work with WiFi – all agree
  • The LWA approach may offer a more tactical alternative
  • Advantages of LWA

As Guy Daniels reported yesterday the 3GPP held a workshop in Beijing this week to discuss the status of Licensed-Assisted Access (LAA) – the standard proposed to enable LTE to operate in the unlicensed spectrum where WiFi plays.

LAA is the European version of the US LTE-U and differs mostly in the way it handles contention. (see – Cellular and WiFi come out to play. Is it BFF for LAA?)

The 3GPP wants to be able to show that the two can play fairly in the same spectrum domain and to come up with tests that both sides can accept will require working in a multi-partisan way to agree the ground rules.

The whole LTE-U/LAA concept has understandably garnered a lot of contention in its own right because of the way it might appear to the suspiciously-minded to be an attempt by licensed telcos to muscle in on WiFi territory and shoulder WiFi operators out.

But one of the reasons many people on both sides of the WiFi/LAA fence seem to be rather untroubled by its probable arrival is that they just don’t think it will work, in the sense that it won’t be adopted by licensed telcos to any great extent.

Why?

Because many believe it’s most likely possible, in the end, to aggregate LTE and WiFi as both technologies currently stand and thus get most of the advantages being sought without going to the trouble and expense of building out a new network. An expense, by the way, that most operators would  like to avoid like the plague. Incremental capacity improvements are thought to be the way forward in the ‘tactical teens’.

And what are those advantages? Essentially, service aggregation across the two domains will allow ‘WiFi first’ operators, like Republic in the US and (from what we can tell) Google with its Project Fi, to have its users benefit from the broad coverage afforded by long range cellular while handling the bulk of the heavy-lifting data downloading via WiFi (public WiFi as well as residential). That ‘best of both worlds’ effect is already being tapped in the other direction by licensed operators who, since the dawn of the iPhone, have been explicitly or implicitly relying on their users toggling over to WiFi for the bulk of their data needs and thus taking the strain off the mobile network.

Developing a relatively ‘seamless’ way of having the two work together by ‘aggregating’ their capabilities is therefore the goal for both WiFi first and ‘cell first’ operators.

The structured way to do this for a mobile telco is to build telco technology and standards into unlicensed territory via LTE-U/LAA. But a cheaper, more tactical alternative is to have effective aggregation of the technologies enabled without building a new network technology – using  a looser coupling called LWA (LTE/WiFi Aggregation) and using the intelligence mostly gathered at the edge of the network (in handsets and servers) to intelligently and dynamically aggregate streams.

For WiFi advocates LWA should be clear winner (at least in the medium term). According to consultant and unashamed WiFi advocate, Claus Hetting, there are so many advantages to the LWA approach that it’s difficult to see why LTE-U could be a serious immediate contender.

Here, in no particular order and without Claus’s precision, are are the main ones.

Cost. This is huge. The reason WiFi has done so well to now is essentially because of its scale and the fact that the silicon needed to drive it has become enormously cost effective. Claus thinks WiFi base stations are and will remain an order of magnitude more cost effective than any alternative LTE-U technology. Telco technology always costs much, much more (which is why telco equipment vendors are so keen on have telco technologies dominate the unlicensed bands too).

Pervasiveness: WiFi is already everywhere, especially in the home. And also in the office. So as it’s already waiting to be aggregated, why would you try to replace it with something which did more or less the same thing with only dubious efficiency advantages?

Approvals: there are already differences in national requirements for running LTE-U – and implementation is not even under way. A global LTE-U market would be fragmented.

Ongoing interworking: Getting telco standards to work in an intimate and still effective way with IEEE standards has always proved difficult if not impossible. It’s been tried, it’s often failed.

Part of the last problem is around standards churn. Tight integration with the network puts a WiFi replacement technology on a long life-cycle whereas WiFi will presumably remain dynamic and ever-improving.

So why the enthusiasm? Perhaps the fostering of LTE-U and LAA is part of a long game, hatched to help telcos eventually win back data access pricing control by dominating the entire spectrum? It’s a motive oft stated, but usually presented in less stark terms.

OnHub de Google, le routeur Wi-Fi qui s’expose


Disponible en bleu sombre ou en noir, le routeur Wi-Fi OnHub de Google veut coloniser nos salons.
Disponible en bleu sombre ou en noir, le routeur Wi-Fi OnHub de Google veut coloniser nos salons.

Conçu pour être placé bien en vue dans une pièce, le routeur Wi-Fi annoncé par Google a été fabriqué en partenariat avec le fabricant chinois d’équipements réseaux TP-Link. Cylindrique, le OnHub mesure 17,8 cm de haut pour un diamètre d’un peu plus de 10 cm.

Google, qui aime bien imprimer sa marque dans tous les domaines, s’est mêlé cette fois de routeurs Wi-Fi. Sous le nom de OnHub, il vient de sortir un boîtier cylindrique destiné à trôner dans les intérieurs soignés. Pas vilain du tout, ce routeur bi-bande ne présente aucune antenne visible bien qu’il en contienne 3×3 de 2,4 GHz et 3×3 de 5 GHz. Il supporte le protocole ZigBee (alias IEEE 802.15.4), le langage Weave développé par Nest Labs pour l’Internet des objets, les liaisons Bluetooth 4.0 et Bluetooth Smart. Selon Google, le OnHub permet de connecter simultanément jusqu’à 128 équipements.

AdTech AdLe routeur est disponible en bleu sombre ou en noir et pèse 455 grammes environ pour un encombrement de 17,8 (hauteur) sur 10,2 cm (diamètre). A son sommet, un cercle lumineux indique s’il est en marche. Comme on pouvait s’y attendre, le routeur peut être mis en place et contrôlé à travers une app mobile (Google On) sur Android et iOS.

Le groupe californien enregistre les précommandes pour ce périphérique (pas encore pour la France) qui doit sortir le 31 août aux Etats-Unis au prix de 199 dollars HT. Le OnHub a été fabriqué en partenariat avec l’équipementier réseau chinois TP-Link et Google dit travailler avec Asus pour développer d’autres produits OnHub.

EN SAVOIR PLUS :

– les spécifications du routeur OnHub

The Roadmap to 2020 at the Wi-Fi Global Congress

By now, you’ve probably heard that the Wireless Broadband Alliance will proudly host the next Wi-Fi Global Congress in San Jose, California, at the San Jose Convention Center on 12 – 15 October, 2015. This will be our biggest event yet, and we couldn’t be happier or more excited to bring the largest global Wi-Fi event to the Capital of Silicon Valley.

Part of what makes the Wi-Fi Global Congress such a great event is that it provides a forum for several different topics to be discussed, debated, and presented upon. These topics are some of the hottest talking points in the Wi-Fi industry, and in San Jose, attendees will have the opportunity to learn and network about a wider variety of topics than ever before.

Tiago Rodrigues, Senior Director for PMO and Membership Services, Wireless Broadband Alliance

The WBA’s Senior Director for PMO and Membership Services, Tiago Rodrigues, was kind enough to take some time and shed a little light on what you can expect to be discussed in San Jose.

Wi-Fi 2020
“Industry leaders will discuss the evolution of Wi-Fi on the road to 2020. This will include the evolution of technology, new business opportunities, the role of Wi-Fi in the wireless space, and the impact that it could have on carriers.”

Smart Cities and Internet of Things (IoT)
“Top innovators and city leaders will share case studies on the deployment of Smart Cities, as well as on IoT business opportunities for Wi-Fi. Some of the most advanced examples of Smart Cities from around the world will be presented.”

Roadmap to 5G
“The WGC will provide a detailed look at how operators are connecting the licensed and unlicensed spectrums in the continued evolution of 5G, and how Wi-Fi is playing an important role in this exciting era. Attendees can expect lots of discussion about the challenges that 5G will face, and how the industry must evolve in order to optimize network capacity and provide the best possible performance for the end-users.”

Carrier Wi-Fi Evolution
“The leading operators in the industry will share methods on maximizing carrier Wi-Fi services and networks. Furthermore, presentations on the impact of services such as Wi-Fi Calling and LBS will give attendees the opportunity to learn more about how these operators are improving their networks to meet the expectations of customers.”

Next Generation Hotspot (NGH) Live
“Attendees will be able to use their own devices to experience the most advanced Wi-Fi services, such as NGH and Wi-Fi Calling.”

Business Opportunity Workshops
“Get face-to-face advice from experts on how to build your business, and learn more about how the WBA can help.”

The Wi-Fi Global Congress in San Jose promises to be an exciting, informative, and enjoyable event – don’t forget to register your interest in exhibiting, sponsoring, and attending the world’s premiere Wi-Fi event by clicking here.

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